Darwinism and the problems of life : a study of familiar animal life

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DARWINISM AND THE PROBLEMS OF LIFE

7

Darwinism

Problems

a Stufci? of jfamUtar animal Xtfe

BY

CONRAD GUENTHER, Ph.D.

Professor at the University Freiburg in Baden

TRANSLATED FROM THE THIRD EDITION

BY

JOSEPH McCABE

NEW YORK

E. P. DUTTON AND COMPANY

31 WEST TWENTY-THIRD STREET
1906

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PREFACE

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The present work had its origin in an attempt to
appreciate the range, the foundation, and the value
of evolutionary theories. Such a task entailed a
prolonged study, not only of scientific literature,
but also of works that belong to neighbouring
provinces.

The information gleaned from these fields had then
to be appraised and put together, and an effort made
to reduce it into a harmonious system. In doing

this the various theories had to be examined with
discrimination, enlarged, and built into the structure.
It is, therefore, hoped that the reader will meet many
new thoughts in the work.

In the preparatory reading the author had to go
through the whole of the relevant literature in various
languages. In the book itself he was compelled to
restrict himself to what had an essential bearing —
either for or against — on the view it presents.

The work has not been written solely for those
who are entirely devoted to the study of science.
It appeals to all who take an interest in scientific
questions ; to all educated people who would inform

6

PREFACE

themselves as to the actual condition of theories of
life.

Its chief aim has been to vindicate the value and
importance of Darwinism. The greater part of the
work is devoted to proving the truth of this system.
On the other hand, every care has been taken to
distinguish between facts and probabilities ; and it has
been clearly pointed out what general deductions may
or may not be drawn from Darwinism. The ease
with which the theory of evolution is grasped too
readily disposes people to regard Darwinism as the
one true, natural, and sound view of the world-
process. And in order to set forth all these questions
with perfect clearness, it has been necessary to touch
on fields of inquiry which lie beyond the range of
biological science.

The manner of presentation is simple, because the
work is written for the general reader. No knowledge
of science is presupposed ; and the reader is briefly
informed on all the questions that have a bearing on
the theory of evolution. Everything that would
interfere with clearness and intelligibility has been
avoided. Hence, the founders of the various theories
treated are not, as a rule, named in the text ; though,
to ensure accuracy, their names are given in foot-
notes. In these notes will also be found the
references to the literature relating to the subject, so

PREFACE

7

that the reader who desires to go further into the
matter will find every assistance. With the same
object of making the text clear the various animals
have been indicated, as far as possible, by their
popular names, but their scientific titles will be found
in the index at the end of the work.

The difficulty of many of the questions treated
imposed a yet further condition. Problems that are
not easily grappled could not very well be put at
once before the reader. The book gradually educates
him up to the level of these. Starting from familiar
objects, it leads him on, almost unconsciously, to
problems of increasing difficulty, until he is at length
in a position to form an opinion on even the most
difficult.

And as it is the purpose of this work to elucidate
the theory of evolution only by means of observation,
to convince those only who have some insight into
the inexhaustible facts of nature that bear witness to
it, as many as possible of these facts have been
introduced. Nature herself shall teach the reader the
truth of evolution. On this account, the first part of
the work has been divided, not into problems, but
according to groups of animals. These animals,
moreover, are generally the familiar ones of our own
country. Our indigenous animal-life has been treated
very fully. Plants have only been dealt with in so

8

PREFACE

far as this was necessary for the reader to understand
the questions.

The book will, therefore, make the reader acquainted
with the animals that surround him, and teach him to
take an intelligent interest in the life of the forest
and the field. In this we have the most natural
foundation for the thoughts that reach out to embrace
the whole of life, and that in the end help to lay
open the entire world to the human mind.

CONRAD GUENTHER.

PREFACE TO THE THIRD EDITION

Little over half a year has passed since the

publication of this work. In so short a space of

time there could not be much advance made in

science, so that it was unnecessary to make extensive

alterations in the text for the present edition. In a

few places there have been additions, relating to new

investigations ; the third chapter, especially, has been

considerably modified. No change was needed as

regards the view that runs through the entire work,

and is summarily presented in the final chapter. I

have carefully examined the objections raised on

several points, but have found them invalid. However,

I thought it proper to put the chief of them before

the reader, because I am anxious that he should use

his own judgment on the facts independently. I have,

therefore, given the objections in the notes, with a

few explanatory remarks. Where the objections were

due to misunderstanding, I have taken care to make

the corresponding passage in the text clearer, or to

add further explanations. The purely philosophical

questions that are dealt with in the later chapters have

not been enlarged on. A more thorough discussion of

9

io PREFACE TO THIRD EDITION

these questions would spoil the unity of the work ; it
was necessary only to put, at the limits of my science,
sign-posts indicating the destination of the roads that
start from these points, and distinguishing the right
from the wrong way. For the rest, I believe that
my treatment of these various questions is not wholly
superficial, but sufficiently informs the reader on the
substance of them. I am confirmed in this by the
testimony of experts.

I have to express my cordial thanks to my colleagues
for their friendly interest.

CONRAD GUENTHER.

Freiburg, 15 th March , 1905.

TRANSLATOR’S PREFACE

The quantity of popular evolutionary literature in our
tongue is — apart from works that deal with the subject
in its relation to religious controversy — so slight that
a fresh work of acknowledged competence should be
assured of a welcome. Professor Guenther’s work
has, however, an especial title to consideration. He
has succeeded so well in taking up the position of the
average untrained observer for his instructive survey
of our animal world that his book will be singularly
helpful to thousands who shrink from the usual technical
manual. The reader will find himself at first looking
out on a familiar world in a familiar way. Gradually
he will find the well - known forms and movements
suggesting alluring problems to his opening vision, and
he will follow the answers to them, given with a logical
ease and literary grace that are too uncommon in this
department, almost without effort.

Dr. Guenther’s facility has not been purchased, as
often happens, at the expense of soundness or thorough-
ness. The limits of the work restrict his plan, but
within those limits the reader will feel that he is
following a judicious and entirely informed guide.
Though full reference is made to the most recent
speculations of biologists, it is not books and authorities,
but Nature, that the author holds steadily in view,
and his personal contributions to its interpretation will
command respect.

1 2 translator’s preface

The circumstance that the work proceeds on a totally
different principle of interpretation than others that I
have recently introduced to English readers gave me a
certain gratification. It is important to make clear that
the superb procession of organic forms across the stage
of our planet, which we sum up in the phrase, “ the
evolution of life,” may be presented either in the terms
of the older Darwinian theories or of the new ones
associated with the great name of Weismann. The
fact of evolution now stands solid and towering above
all the clash of theories. Even the machinery of natural
selection continues its vast work — if it does not increase
it — whether or no we accept the transmission of acquired
characteristics. It has seemed most expedient to put
before the general reader a simple and untechnical
interpretation of evolution from the Weismannic point
of view (within limits) ; and it would be difficult to
find a more suitable and attractive one than Professor
Guenther’s Darwinism.

JOSEPH McCABE.

London, October , 1905.

CONTENTS

PAGK

CHAPTER I. — Introduction

Animal-life in the forest, the field, and the pond. Variations of
animals in different regions. Connection of animals in the
same region. Over-production in nature. The relation of
increase to the danger of destruction. The struggle for
life. Artificial selection. Natural selection. Transforma-
tion of species. Different animals of former days as the
parents of actual organisms. The theory of evolution.

Its predictions. Variation and heredity. Useful and
harmful animals. Modification of our animal -world
through civilisation - - - - - 19

CHAPTER II. — Mammals

Life of mammals. Protective value of colour. Origin of
colour. Hibernation. Store-rooms. Increased produc-
tion or diminished peril of destruction. Why mammals do
not multiply more. The play of animals. Explanation
of play by rest and the accumulation of energy. Human
play. Imitation in play. Explanation of instinct. Instinct
and intelligence. Exercise of the mind in the games of
children. Pleasure in play. Conscious self-deception,
imagination. Play and art. The animal is at the threshold
of art. Sense of freedom in play. Games of children.
Attention. The use of curiosity. The mind of the
animal and of man - - - - - 52

CHAPTER III.— Birds

Sexual selection. Choice of females. Rejection of the
hypothesis. Advance of the male’s senses. Selection of
the strongest suitor. Explanation of coyness and the
animal coquette. Female selection inadmissible. The
love -dance. Selection of the apparent strongest.
Colours as means of distinguishing species. Use of
sounds. Pairing-calls. Origin and forms of song. In-
strumental music of the birds. Migration. Speed of

13

14

CONTENTS

flight. Do birds tire ? The adaptations of the bird-body.
Height of the migration-flight. Origin of migratory birds.
Their strength, their power of presentiment. Routes of
migrating birds. Their memory and sense of direction.
Travelling in flocks ....

CHAPTER IV. — Reptiles and Amphibia

Principle of animal-classification. The general properties of
animals explained by heredity and adaptation. Darwinian
justification of classification. Reptiles and amphibia of
former ages. Earlier periods of the earth. How and why
the earth has changed up to the present. How the remains
of earlier animals have been preserved. Gaps in the
remains of extinct animals. Primitive man. Conflicts of
extinct animals. Why the gigantic forms of earlier ages
became extinct. The death of species. Transformation
of species. Why ancient species have been preserved.
Why there are still animals of the simplest type. Pre-
dominance of a species of animal. Predominance of man.
Any variation is possible. Origin of flying animals. Life
of our reptiles. Prey. The creeping of serpents. Re-
generation, the power to re-form lost members. Its origin
by natural selection. Frog-spawn. The skin of amphibia.
Repellent and warning colours on nauseous and poisonous
animals -

CHAPTER V.— Fishes

Origin of terrestrial vertebrates and of lungs. Similarities in the
structure of animals. Transformation of organs. Creation
or evolution? Many animals are worse than others in
this. Selection only creates what is necessary. Atrophy
of useless organs. Rudimentary organs in man. Degenera-
tion of organs by panmixis. Indifferent characteristics of
animals. The differences between species are adaptations.
Correlation. Animals that are beyond the range of
selection, Qualities and quantities. Explanation of
atrophied organs by economy of sustenance and negative
selection. Impossible to explain many rudimentary organs.
The biogenetic law. Gills in the human embryo. Pre-
datory fishes. The rhodeus and the pond-muscle. Senses
of fishes, their dangers. History of the eel and the salmon.
Artificial selection of fishes

CONTENTS

15

PAGR

CHAPTER VI. — Tracheates

To the tracheates belong spiders and insects. How insects
grow. Explanation of the metamorphoses of insects.
Protective colouring on the wings of butterflies. The
Lamarckian principle refuted by protective colours.

Insects that resemble objects. Mimicry. Exhalation
from male butterflies. Sexual selection. Origin of

flowers due to insects. Parts of the insect’s mouth.

Refutation of the Lamarckian principle. The coat of
insects cannot have arisen by use. Harmonious adapta-
tions, co-adaptations. Co-adaptations that Lamarck cannot
explain. Explanation of co-adaptations. Are instincts
inherited habits? Instincts that can never be affected
by the will. Spider’s webs. Care of the young. Instincts
that are only used once. Are mutilations inherited ? Pro-
tective marks, mildew marks, foresight. Infection of
embryo. Structure of the embryo. The inheritance of
acquired characters is difficult to conceive. Untenability
of the Lamarckian principle - - - - 184

CHAPTER VII. — Crabs and Molluscs

Economy of nature. The chemical constituents of bodies.
Chemical combinations. The elements. The albuminoids.
Biogens as constituents of living matter. Vital phenomena
and apparent death. Metabolism. Structure of the living
substance. Plants the foundation of life. Order of
sustenance in nature. Flesh-eating is more natural to
the animal than plant-diet. Are all variations useful to
animals? Value of selection. Origin of the shells of
snails. Change of functions. Development of the crab.

Why the embryonic development of an animal reproduces
its racial history. Reconstruction of embryogenesis.
Uncertainty of the biogenetic law. Parthenogenesis,
the development of unfertilised eggs. Significance of
the germ - cells. Significance of sexual reproduction.
Amphimixis. Plural variations - - - - 228

CHAPTER VIII. — Worms and Ccelenterata

Genealogical tree of the animals. Descent of animals. Descent
of man. Preservation of intermediate forms. The earth-
worm. Regeneration. Leeches. Parasitism. Origin of

i6

CONTENTS

rAGB

parasites from free animals. Organic changes in parasites.

How parasites are conveyed. Exchange of hosts. Life of
the chief parasites : Trichinae, maw-worms, dochmius,
tape-worms, etc. Danger of fins. Development of the
liver-distoma. Friendships of animals. Symbioses - 262

CHAPTER IX.— Protozoa.

The animal built up of cells. Principle of division of labour.

The greater the division of labour, the higher the animal’s
organisation. Multicellular and unicellular animals. The
protozoa, their form and reproduction. Structure of an
animal in its development from the ovum onwards from
rudimentary parts. Origin of the germ-cells. Outlines
of a theory of heredity. Amphimixis of the protozoa.

Origin of sexual reproduction. Formation of seed and
ova. Continuity of the germ-cells. Are any animals
immortal? Death is not common to all animals. Origin
of death. Permanent and temporary life. Has life come
from the stars? Origin of life on the earth, spontaneous
generation. How it is to be conceived. The first develop-
ment of living matter. Formation and significance of the
cell - nucleus. Significance of the fundamental parts.
Relation of the rudimentary parts in amphimixis. When
life is extinguished ------ 288

CHAPTER X. — Extensions of the Principle of
Selection and other Involuntary Theories

Why there are numerous species to-day. Isolation facilitates
the divergence of species. Modification of isolated animals.
Movement and alteration of animals. Are species formed
by isolation even without the aid of natural selection ?
Definite variations. Germinal selection. Changes in the
nutrition of the embryo are the foundation of variations.

Do useless organs disappear through germinal selection ?
Refutation of germinal selection. Effect of external in-
fluences as modifying principle. Orthogenesis. Rejection
of same. The mutation-theory. Variations and mutations.

Do variations proceed indefinitely ? Is there a formative
energy in organisms ? Mechanicism and vitalism. How
are the form and purposiveness of organisms explained?

What is to be understood by chance. Absence of purpose
in living things. The will to live, the instinct of self-
preservation 3 2 4

INTRODUCTION

33

spicuous shade of colour, otherwise the animals would
show themselves against the grey soil, and would be
more easily found and captured.

All these characteristics of the hare are continually
improved by natural selection, as only those can escape
their enemies that are best qualified to do so. But
as their enemies also are subjected to an improving
selection, higher qualifications will be required in the
next generation, and so on. In other words, the hares
will advance in each generation. It is true that we do
not directly observe this progress, but that is only
because our life is too short to appreciate the changes
brought about by natural selection, which require long
periods of time. Natural selection cannot act with the
same intensity as artificial selection. In the case of
the hare, for instance, not only two or three of the
swiftest survive, but a large number, and amongst
these many slow ones that have managed to escape
destruction by a favourable accident. It is only on the
average that the speediest survive, and, in fact, when
we take an average of many years, so that it will be
thousands of years before any appreciable result can
be seen. We do not see the grass growing, but we
can prove that it is longer to-day than it was yesterday.
So, if we could raise from the dead a man who had seen
a hare thousands of years ago, he would find a difference
in the hare of to-day. In point of fact, the skeletons of
animals belonging to earlier ages prove that they were
different then from what they are in our time.

But we should greatly underrate the power of natural
selection if we attributed to it only the capacity to

c

34 DARWINISM AND THE PROBLEMS OF LIFE

increase already existing characteristics. Just as
artificial selection can produce white pigeons from birds
of a grey-blue colour, by choosing in each generation
the specimens with the largest number of white spots
in their plumage, so natural selection can endow animals
with entirely new features. Thus, for instance, our
hare is not easy to distinguish from the ground on which
it browses because of its grey colour — which is a mix-
ture of brown, yellow, white, and black . 1 Now let us
suppose that a glacial period came over England again,
as has happened twice in the history of the earth. The
dark-coloured hares would then easily meet the eyes of
their enemies on the white snow, but there would be
varieties with a rather stronger mixture of white in
their colouring. These would be least easily seen,
would survive the longest, and bring most young into
the world ; so that the next generation would in itself be
of a lighter shade. Amongst these, again, the lightest
would survive best, and this would be repeated in each
generation until a pure white coat was produced, as is
found in the Arctic hare. We must not forget, of
course, that such a modification of colour could only
take place if the cold set in gradually, and implied
above all the coming of longer and more snowy winters.
Natural selection is powerless in face of sudden changes,
as it can only modify things gradually. Further,
selection only acts generally ; every animal does not
survive that is modified in the desired direction. But
that the modification can, generally speaking, advance

1 As mentioned in Weismann’s “ The Evolution Theory.” [English
Translation.]

INTRODUCTION

35

in this way is due to the fact that the material to select
from is inexhaustible, and that immense periods of
time are available for the process of transformation.

We see, therefore, that the changes that are brought
about by natural selection, through the emphasising of
insignificant characteristics, may become very striking.
The external difference between grey and white hares
is very considerable. It is true that one might claim
the white hares to be a. variety of the grey ones, and
say that the difference between the two forms is not as
great as between the hare and the next species, the
rabbit. But is there any difference between a “ variety ”
and a “species”? Many writers understand by
“ varieties ” animals with somewhat different features
from those of the mother-species, but say that these
characteristics vacillate, and are not preserved in the
course of generations — are not constant , as the phrase
is. We see that this test of the variety does not hold
good in the case of our white hares ; the whiteness is
constant, because all reversions are destroyed. And
when it is said that the variety can always pair with
the mother-species and produce fruitful offspring, which
cannot take place between two different species, the
statement is not entirely correct. Many species can be
coupled, and beget young that are capable of repro-
ducing. This is the case, for instance, with the wolf
and the dog, the carp and the crucian, and other
animals, which everybody recognises as distinct species.

We can safely affirm to-day that there are no rigid
tests for determining whether certain types of animals
are species or only varieties ; in other words, there

36 DARWINISM AND THE PROBLEMS OF LIFE

is no sharp distinction between a species and a
variety.

This modern discovery has thoroughly shaken the
old Linnean principle : “ There are as many species
as there were distinct forms created.” We now know
that species are changeable, and have actually changed ;
that one species may be formed from another. The
question is often raised, in the form of an objection,
why no species has been changed within our experience ;
in fact, it is urged that history shows the forms of
animals and plants to be just the same as they were
6,000 years ago, since the ancient Egyptians depicted
lions and other animals just as we have them to-day.
The objection seems to have some strength, but we
know of several cases in which species have been
so much modified within the historical period that
they can no longer be crossed with their earlier
relatives.

In the year 1419 rabbits were introduced on the
isle of Porto Santo, near Madeira, and increased until
they became a plague of the country. But the de-
scendants have become very unlike their ancestors,
and differ from them in their peculiar colour, rat-like
shape, small size, nocturnal habits, and extraordinary
savageness. But the most remarkable point is that
they can no longer be crossed with the European
rabbit, and have, therefore, formed a new species in
this comparatively brief space of time. 1

However, this was an exceptional case. The

1 The facts are related by Ernst Haeckel, who gave the Porto Santo
rabbit the name of Lepus Huxleyi.

INTRODUCTION

37

conversion of one species into another usually
requires a longer period than the whole of human
history, the 6,000 years of which are only an hour
in comparison with the immense duration of the history
of the earth. We saw above that it takes a long time
for grey hares to become white ; and we know from
geology that, as a matter of fact, all the terrestial
epochs comprise enormous periods of time. The latest
of them, the tertiary period, is calculated at several
hundred thousand years. Geology also gives us the
best idea of the mutability of species, as we find at
the bottom of the sea the remains of animals of
remote ages, which are totally different from the
animals of our time. Geologists can distribute the
various strata of the earth’s crust in their chronological
succession. These strata are the pages of a book that
it has taken millions and millions of years to write.
Nowhere in it do we find the animals of our own
time, or at all events only in the very latest periods
of the earth’s history ; and the later the remains of
extinct animals are, from the geological point of view,
the closer do they come to the living fauna. It seems
clear, therefore, that the animals of modern times
were not present at the first creation of life, but only
came into existence at a later date, and succeeded
other animals in the dominion of the earth. But
whence did they come so suddenly, if they were not
evolved from other animals ? Every animal lies in
the body of another before birth, in the form of an
e gg or ovum. But, clearly, before our animals
appeared there were only forms of a different character ;

38 DARWINISM AND THE PROBLEMS OF LIFE

and therefore we may safely conclude that they have
been evolved from these, and that in the course of
generations the children have diverged more and
more from their parents.

If we go further back in the story of the earth’s
growth, we find that each period of geology has its
characteristic animals, which must be the parents of
the later and the offspring of the earlier forms. When,
moreover, we pass in review before the eye of the
mind the animals of the succeeding epochs, we notice
something else besides the unceasing changes of form.
The older the period we take, the simpler we find the
shapes of living things ; and the nearer the period
approaches to our own time, the more intricate and
the higher is the organisation. In the earlier periods,
for instance, we find only the lowest forms of vertebrates,
and these only very sparingly. Gradually, the number
of species increases. Lizards, birds, and mammals
appear ; and amongst these the higher species come
in succession, the carnivores, the apes, and, finally, at
the last moment from the geological point of view,
we find unmistakable proofs of man’s existence and
activity.

Hence geology drives us to the conclusion that the
animals of our time descend from simpler forms, these
from yet simpler ones, and so on, so that only the very
simplest organisms can have arisen at the first creation
of living things. There was, for instance, a time when
only the very lowest types of vertebrates, the fishes,
were present on the earth ; and while a good many of
these fishes were modified in the following epochs

INTRODUCTION

39

without going outside the range of the fish-class, others
were so appreciably changed as to become salamanders.
Geology shows, in fact, that at a certain period sala-
manders were the only vertebrates on the earth beside
the fishes. We do not find these at the earlier stages ;
they can only have been evolved from the fishes, as
these are the nearest to them of all the animals that
lived at the time, and the structure of the salamander
approaches so closely to that of the fish that we can
conceive the period as sufficient for the transformation — •
a transformation which is far less considerable than the
conversion of a worm into a salamander.

From these salamanders the actual salamanders and
frogs must have descended on the one hand, and
the reptiles, leading on to the birds and mammals, on
the other. We may form a picture of the transformation
of animals with the figure of the tree. At a certain
period a side-branch, the fishes, grew out of the trunk ;
the branch grew on, and put forth another side-branch,
the salamanders, which in turn sent out branches. Thus
we can compare the growth of the organic world with
the growth of a tree. At first there was a single trunk,
the simplest organisms. Branches grew out from the
trunk, and in turn produced twigs, until a mighty tree
arose with many branches and innumerable twigs.

The view that the animal kingdom was developed in
this way from the simplest forms is called “ the theory
of evolution .” 1 It is now generally accepted ; there are

1 Also the theory of descent, or transformism. We must carefully
distinguish between : i, the statement that living organisms have been
developed from other forms , and 2, the theory as to how they were
developed, and by what forces. The first is the theory of evolution, the

40

DARWINISM AND THE PROBLEMS OF LIFE

few zoological and botanical works written to-day that
do not rest on or presuppose this theory. An immense
amount of proof in favour of it has been accumulated.
Many predictions that were made on the strength of it
have been realised by recent research, and prophecies
of this kind are, when they are fulfilled, the very best
proof of the correctness of the principles they are
grounded on.

If, for instance, the birds were evolved from the
reptiles, there must have been at a certain stage, since
the tranformation was gradual, an animal intermediate
between the reptile and the bird — an animal that was
really a bird, but still retained unchanged many of the

second the theory of selection ; but there are a number of other
theories with regard to the mode and agencies of development. These
will be given later on. Hence those who accept the theory of evolu-
tion are not at all compelled to subscribe to the theory of selection ; in
fact, there are many evolutionists who reject it. This will be quite
clear if we remember that even in the Bible evolution is, in a certain
sense, laid down as fact. It is stated in the Mosaic books that all the
actual races of men, with their great differences in the colour of the
skin, etc., descend from one couple. Hence theologians have seen of
late that it is not advisable to reject evolution altogether. In par-
ticular, a Jesuit writer, Father Erich VVasmann, one of the first
authorities on ants, has accepted the general theory of evolution in his
work : “ Modern Biology and Evolution.” He holds that in the
beginning God created a number of species at all stages of organisation,
including man. But these species have not remained unchanged.
They were endowed by the Creator with the capacity and the means of
evolution. Thus we have an attempt to combine an acceptance of
evolution with a belief in the verbal inspiration of Scripture. It is not
likely to satisfy the man who seeks thoroughly to understand the world.

The theory of evolution was formulated before Darwin ; the theory of
selection was created by him. But the theory of evolution itself owed
its great advance to Darwin’s book, chiefly because he provided the
explanatory hypothesis of selection. Hence it is not improper to
include both theories under the title “ Darwinism.”

INTRODUCTION

41

characteristics of the reptile. Now, we have found two
well - preserved skeletons of a reptile - bird of this
character. This “archaeopteryx” has the distinctive
feathers, beak, pelvis, and feet of the bird, and at the
same time an articulated lizard-like tail, teeth, and well-
formed toes on its fore-feet, which project far out from
the wing and are not found in any actual bird, but only
in the reptiles.

A second example :

Our horse has only one toe, and on this the hoof is
placed. The other mammals, even the lower ones,
from which it must have evolved, have several toes ;
and thus there must have been at a certain stage horses
that had at least rudimentary traces of the other toes,
besides the developed one.

As a matter of fact, we have discovered four-toed
horses in the geological strata. Indeed, we have
brought to light in the successive strata skeletons of
horses that illustrate every stage of transition from the
ancient four-toed to the modern one-toed horse ; and
the nearer the remains approach to our own time, the
less trace do we find of the other three toes.

We could quote a large number of transitional forms
from geology, but will be content with these. Let us
recall to the reader the way in which we arrived at our
theory of evolution. We sought to show that natural
selection can transform one species into another, and we
found that such a process has been going on uninter-
ruptedly in geology. The question arises, therefore :
Is it natural selection that thus brought about all these
transformations? Is this the artist that has produced

42 DARWINISM AND THE PROBLEMS OF LIFE

the whole of our living organisms from the simplest
forms ?

We may at once say that we answer in the affirmative,
and that we will justify our answer in the following
chapters. We shall even go further, and endeavour
to prove that natural selection is the sole principle
to be used in explaining the evolution of living things.
There are other theories in regard to the transforming
agencies in the organic world, and one of the chief of
these theories was expounded by Lamarck before
Darwin’s time, and accepted by Darwin himself. This
theory affirms that external influences, such as cold or
heat, have a modifying action on a species of animals,
and that the modification they produce may be
transmitted to offspring. It further affirms that an
organ may be strengthened by exercise, and that this
improvement in the organ is handed on to offspring,
and thus by continued use a change of the organ may
be brought about. According to Lamarck, these factors
may go so far as to produce new species.

For the moment we will refrain from testing the
correctness of this hypothesis, and will return to the
general starting-point that led us to consider natural
selection and the theory of evolution. But first of all let
us put more clearly and succinctly what we have seen
as to the changes of species by natural selection.

Natural selection demands two general conditions for
exerting its influence. In the first place, the offspring
of a parental couple must differ in some degree from
each other, or there must be variations ; in the second
place, the characteristics of the parents must be trans-

INTRODUCTION

43

missible to their offspring by heredity. But both these
are facts that no one can call into question, as they
come before us every day. We see daily how brothers
and sisters differ from each other, and at the same
time how many peculiarities of the father and mother
are handed on to their children. These two factors
are the chief means by which natural selection works,
producing one species from another. We have seen
above the way in which it does this.

Let us recall the process. Every species is found to
be over-productive in reproducing itself ; that is to say,
it brings into the world a larger progeny than there is
room for. A great number of these, therefore, must
fall victims to unfavourable conditions or to enemies,
and these will be — as a general rule, and apart from
accident — precisely the least endowed in body and
intelligence. In other words, those animals will survive
longest and reproduce most which are in every respect
— as to inclement weather, enemies, and so on — the best
able to resist. Thus the fittest among the varieties
that casually arise will be preserved, and their useful
characters will be accentuated in the course of many
generations, since each new generation over-produces
in turn, and natural selection again chooses the best
to survive. If the new characters are connected by
intermediate forms with those of the parental species,
which may have adapted itself to the struggle for life in
the original form in some sheltered locality, we may still
speak of varieties. If the intermediate forms have died
— an d that will quickly follow — it is clear that animals
with completely distinct characters will be left, instead of

44

DARWINISM AND THE PROBLEMS OF LIFE

animals in which neither the old nor the new features
were quite distinct ; that is to say, we have now to deal
with two species. The differences between them may
become so great in the course of time that crossing the
two may give sterile offspring, or be altogether
impossible. Thus we see that varieties are species in
the making ; species are varieties that have become
fixed.

We know now what natural selection is. The best
equipped animals escape the longest from destruction by
enemies or from other injury. They are thus enabled
to leave most offspring, and the next generation shows
an average improvement.

Now let us return to the bioccenoses.

We examined life in a particular region, and
concluded that the number of animals in it varies
somewhat, but remains about the same on the average.
In this we assumed that the locality retains its natural
condition, and that, especially, man does not intervene
with his artificial culture. It will be quite otherwise if
civilisation comes on the scene ; then the impenetrable
forests will give place to fruitful fields, and boats will
shoot up and down the river that flows by. This
transformation of Nature must naturally lead to a change
in the fauna ; and the question arises to what extent this
will be modified, and whether man, for instance, can
extinguish, with his improved methods of hunting and
his instruments of destruction, the animals that are
harmful to him and increase those that are useful, in the
forests which he leaves standing.

We have to inquire first, therefore, which animals

INTRODUCTION

45

are harmful and which useful to man, and, however
strange it may seem, this question is very far from being
entirely settled. We do not regard the matter from the
point of view of the hunter, who takes everything to be
harmful that menaces his safety, even if it is a question
of animals which are most useful in every other respect.
By harmful we mean only what is really injurious to
civilisation, or that restricts man’s efforts, while
guarding ourselves against too narrow a view. Game,
for instance, does a lot of harm in the field and the
wood, but compensates us so richly with its flesh that
we readily overlook the mischief it does in the corn
or on the trees. The field-mouse is always mis-
chievous, and its enemies are useful to us. The chief
of these are the owls, which live almost entirely on
mice. But we might go further, and regard almost all
our birds of prey, except, perhaps, the hawk and
sparrow-hawk, as useful on account of their destruction
of mice.

We can determine the food of birds of prey with
some confidence, but it is not so easy in the case of the
insectivorous birds. It is among insects that we find
the chief enemies of culture. There are the typographer-
beetle and the caterpillar of the processionary butterfly,
the pine lappet-moth and the black-arches — all injurious
in the wood — the swarm of grass-hoppers, and especially
the dreaded migratory locust that so often ravages the
fields. The cockchafer is equally injurious in its adult
state and when it is a young grub ; and whoever has
been in a wine-country knows what it means for the
dreaded phylloxera to get into the vineyards. But it

46 DARWINISM AND THE PROBLEMS OF LIFE

would be a mistake to imagine that every insectivorous
bird is useful. We have a large number of useful
insects. I need only mention the bee and the silk-worm,
and the insects that do us a service by destroying their
neighbours. Many a caterpillar succumbs to the large
running beetle, many a plant-louse is eaten up by the
larvae of the lady-bird, and it has been observed that
trees visited by ants do not suffer from caterpillar-blight.
But it is especially the ichneumon-flies, slender animals
with long antennae, darting constantly here and there,
that protect us from this blight. These insects have
what is called an “ovipositor” on the hind part of the
body, with which they stab the caterpillar, and deposit
their eggs inside it. The larvae of the flies develop from
the eggs in the flesh of their unfortunate host, and
gradually feed on its body from within. The process
goes on for a long time, the caterpillar continuing to
live and eat, and it is only when it reaches the chrysalis
stage that the larvae creep out, and enter on that stage
themselves near, or on, the dead covering of their
former host. Many a butterfly - collector has been
disagreeably surprised when he caught an apparently
sound caterpillar of a cabbage-butterfly in his cage, and
found one day an empty shell instead of the expected
chrysalis, with the yellow, oval cocoons of the deadly
enemy of the caterpillar beside it.

The ichneumon-wasp is so thorough in its activity
that it must be put higher than the birds as a destroyer
of caterpillars. We must not, for instance, have too great
an idea of the work of the cuckoo, which was formerly
regarded as the chief agent of destruction of the

INTRODUCTION

47

processionary caterpillars, that not only destroy whole
forests of oak, but also cause violent inflammation on the
human skin by their hairs. It has been proved that
most of the caterpillars eaten by the cuckoo were
already stabbed by ichneumon-flies. Thus they were
already full of larvae, which would have attacked
caterpillars in turn after they had crept out. These
were destroyed by the cuckoo ; and, as they would have
proved the most effective restriction on the plague of
caterpillars, we should regard the cuckoo rather as a
harmful than a useful bird.

What do we find in the case of other insectivorous
birds ?

Unfortunately, we have to class many of them as
mischievous which were generally regarded as useful.
The redstart only too often visits the hive for the
purpose of filling its stomach with the useful honey-
bearers. The fly-catcher destroys the caterpillar-flies
— the bitter enemies, as the name indicates, of the
caterpillar. The kingfisher, of which anglers complain
so bitterly, feeds mainly on water-boatmen, the stinging
water-bugs that are very dangerous to the young fishes ;
it ought, therefore, in this respect to be considered
useful.

But we need not delay any longer in determining
which animals are useful and which mischievous. I
believe that the harm done by the higher animals,
especially mammals and birds, is never serious enough
to justify us in making every effort to destroy them.
We have seen that in a bioccenosis all animals are
related to each other, and that the multiplication of one

DARWINISM AND THE PROBLEMS OF LIFE

species leads to an increase in the number of its
enemies. Moreover, it often happens that a dispro-
portionate spread of any particular species carries its
own corrective with it ; the animals show symptoms
of disease, and die off suddenly as if by magic. This
was seen, for instance, during the great plague of mice
on the Rhine in the twenties ; and the plague of black-
arches at the beginning of the nineties also came to a
sudden stop.

It is true that the injury already done by these swarms
of pests is so great that men are not disposed to wait for
the end, but make every effort to check their progress.
But it is otherwise with animals which cannot multiply
in this extraordinary way. These should be spared, I
think, even if they do a little damage here and there.

Just as we protect singing birds for their song, we
should also try to preserve animals that afford pleasure
to the eye. We ought to forgive the squirrel his taste
for bird’s eggs, or even for the callow young, for we
should greatly miss this graceful animal, the ape of our
forests, if he ceased to enliven our trees. What does it
really matter if the kingfisher does destroy a few fishes
a d a y — and generally fishes that are no use to us ! He
makes up for that by his beautiful appearance. How
sad it would be if we were to lose for ever the unfor-
gettable moments that come to the solitary dreamer by
the stream when he catches sight of this bird with its
plumage of jewels ! What an impiety to shoot a stork
because he has stolen a young hare ! When we were
children the stork was almost a sacred bird to us with
his inexhaustible poetry. Let us leave him such to

CONTENTS

17

PAGE

CHAPTER XI. — The Mechanical Conception of
Life and its Limits

An attempt to refute the theory of evolution. Establishment of
theories and investigation of details. Causes and effects.

Infinity of same. Impotence of science. Infinite variety
in the products of organs. The infinite diversity of the
universe. Purpose. Mechanical and teleological causes.

There is no end in the development of animals. Sexual
selection, orthogenesis, and germinal selection are teleo-
logical. Purification of the theory of selection from
teleological elements. There are no higher and lower
animals. A high grade of organisation gives no more
advantage to an animal than a lower. Natural selection is
not an absolute principle of betterment. The scientific
method of research. Infinite diversity of the universe.
Comprehension of same by concepts. Abstraction of the
universal. What a natural law is. Ultimate constituents
of bodies. Comprehension of the world by ultimate
elements. Mathematics. An ether without properties
enables us to grasp the world. Does ether exist? Are
psychic processes to be conceived corporeally ? The
methods of psychology. Consciousness. The world and
the soul are only to be conceived as contents of
consciousness. Transition from science to theory of
knowledge ------- 358

CHAPTER XII. — Nature, History, and Morality

Truth of scientific ideas. Why the universal seems to us more
essential than the individual. The ideas of animals. Why
we take ideas for realities. Thinking realities into ideas.

Is there a real world lying behind the phenomenal world ?

Natural science itself is a human product and pursues an
aim. It must not regard itself as the only sound branch
of science. The historical sciences. Their method. The
historical elements in natural science. The laws justify
historical research. The science of evolution rests on
probabilities. The origin of the human mind. Had
consciousness a beginning? There never were absolutely
simple bodies. History and sociology. Origin and
development of primitive man. Origin of good and
evil. Origin of conscience. Advance of civilisation by
tradition. Language. Conflicts of nations. Scientific

B

i8

CONTENTS

ethics. Restricted and inverted selection in civilisation.
The evils of war and militarism. Nietzsche’s egoism.
Darwinian ideas of the social future. Insipidity of the
Darwinian ideal. Social man according to Nietzsche.
Natural science knows no idea of duty. It knows nothing
of values, and can therefore frame no ethic. Preservation
of existence is not preservation of value. Is there a sense
of life? Monism. Presuppositions of science. The idea
of duty is the beginning of all knowledge. Conclusion

Index - -

/

PAGE

39 °

429

DARWINISM AND THE PROBLEMS OF LIFE

CHAPTER I

INTRODUCTION

Animal-life in the forest, the field, and the pond. Variations of
animals in different regions. Connection of animals in the same
region. Over-production in nature. The relation of increase to
the danger of destruction. The struggle for life. Artificial
selection. Natural selection. Transformation of species.
Different animals of former days as the parents of actual organ-
isms. The theory of evolution. Its predictions. Variation and
heredity. Useful and harmful animals. Modification of our
animal-world through civilisation.

I

Who has not visited the forest on a morning in Spring!

The tall stems of the trees stand out ruddily in the
green dawn. The blue vault of heaven breaks through
the tree - tops above. The dew - drops glisten like
diamonds on the tender moss and the grass - blades ;
and iridescent prisms flash from the leaves of the
shrubs. A mist lies on the glade, and covers with its
veil the flowered-starred ground, while the tips of the
young firs rise mysteriously from its depths.

Then the morning wind stirs the tops of the trees.

A faint rustle passes through the wood. Here and

*9

20

DARWINISM AND THE PROBLEMS OF LIFE

there branches and stems give out mysterious creaks
and groans.

Now the noises increase.

On the ground a slight stir catches the ear. It is
a beetle hurrying by in search of his prey. He runs
nimbly over the grass and among the bushes. He
leaps over a scarlet snail, which draws in its antennae in

alarm, and passes swiftly down an ant-track. Before

* *» * ** * * * * *

the.- industrious builders realise the injury done to their
laborious construction, he has disappeared in the thicket.

A dreamy .murmur fills the ear.

Fifes without number are in the air. Their pellucid
wings glitter in the rays of the sun, and they poise
motionless, as if hanging by a thread. The whole
atmosphere seems to vibrate with the tone of the harp.
An infinite harmony swells the breast of the traveller.

At last the stillness is sharply rent.

Like the laughter of some spirit of the forest, the loud
“ gluck, gluck, gluck ” of the wood-pecker echoes
through the trees, and the ringing tap tells that his
fellows are at their carpentering. The cry of the
chaffinch resounds ; from point after point comes the
chirp of the wood-pigeon ; and the titmouse utters
without wearying its tender call.

Over the clearing is heard the cry of the bird of
prey. The mist falls on the meadow. And yonder,
where the thick bush marks off the forest from the
flower-decked green, a slender deer emerges, lifts up
its narrow head cautiously, looks all around, and then
bends its neck towards the grass.

INTRODUCTION

2 1

When the sun is at its zenith, life is at its busiest
in the field.

A hot fruitful vapour rises from the grass up into
the blue air, which is filled with the trilling song of
the lark. The ears of corn stand motionless in the
dry air ; only here and there a blade stirs and betrays
the passage of some invisible inhabitant of the field.

But life is briskest in the field at the point where
the flower-filled ditches, crowded with rich vegetation,
are found. Here the bees and wasps hum from flower
to flower : white, blue, and many-coloured butterflies
dart about ; and the ground swarms with running insects.

Beetles creep up the trunks of the willows that stand
at the border, and their leaves are the pasturage of the
insatiable caterpillar. On a branch of the tree sits the
wood-lark, and begins his song. Then inspiration comes
to him ; he rises, and mounts to the sky, pouring out
his song in triumph as he ascends. At last he spreads
his wings, and with long-drawn notes sinks to earth
once more.

*••••••

Now evening approaches, and the rays of the sun fall
almost level ; the frogs give forth their round song in
the rush-bordered pond.

Here, again, is an entirely new picture.

The great dragon-flies dart rapidly over the water,
and their dark-blue wings glint like fairy-eyes from the
rushes. A crowd of gnats and May-flies dance above
the surface. On it the whirligigs form their endless
circles, like shining pearls ; and, like long-legged skaters,
the water-ticks glide hither and thither.

22

DARWINISM AND THE PROBLEMS OF LIFE

A red-bellied newt issues from the dark depths to get
a mouthful of air, and, turning gracefully, sinks again.
A large swimming beetle appears, and hangs with its
hind part on the surface. The depth of the water is
full of water-fleas, which rise up and down unceasingly
like unnumbered points.

• «<»•••*

And when the sun sinks below the horizon, and
darkness enfolds Nature in its thick veil, a new life
awakens.

The call of the screech-owl resounds plaintively in
the wood, bats fly about in the air, and a gentle rustle
is heard in the grass.

Fear falls on the man who enters into the soul of
the little night-walker, which must make its way in
the dark, and must be ready at every step to be seized
by some deadly unseen enemy. Never does the eternal
carnage in Nature seem so merciless, so terrible, as in
the night.

• •••••

Each hour of the day has its own life.

In the forest, the field, or the pond the picture differs
entirely in the morning, at midday, in the evening, and
at night. If our path had led us into one of these three
regions, as we call the various provinces of Nature, at
another time of the day, we should have encountered
different animals. Yet the animals of any one region
are more closely related than those that live in different
regions at any particular time of the day. Forest,
field, and pond have their characteristic inhabitants, and
outside these regions there is a whole series of others.

INTRODUCTION

2 3

If we examine the brush instead of the open wood
we meet animals just as interesting and characteristic ;
and instead of the field we might have taken the
meadow, the moor, or the quarry.

So the life of the pond differs entirely from the life
of the brook and the great river. Nay, we might even
confine ourselves to the tiniest compass, and examine
only a drop of water hanging from the moss. We
should find that even in this little realm there are
hunters and hunted, and that countless living things
find the conditions of their life within these narrow
limits.

Every animal seeks what it needs for its maintenance,
if not exclusively, at all events mainly, in the particular
region in which it lives. The wood-pecker will not
leave the wood, for this alone provides him with
food in its trees and a sure place for nesting ; nor are
river-fishes ever found in ponds.

But all animals are not confined to one region. The
deer leaves the thicket in the evening to feed in the
green meadows ; the partridge seeks cover at times in
the wood ; the water-beetle of the pond may alight in
running water in its nocturnal flight.

Other animals have a different habitation at different
periods of life.

The young frogs swim about merrily in the water,
and resemble fishes in appearance and habits. After-
wards the long oar-like tail is lost, the feet sprout out,
and the frog assumes the form of a land-animal. It
lurks for flies at the edge of the pond, and only leaps
into its earlier element on the approach of danger.

24

DARWINISM AND THE PROBLEMS OF LIFE

But Nature may go yet further. It may make the
habitation of the young animals fatal to them as adults.

Many insects pass their youth in the water in the
form of larvae, but after their last cast of skin they
unfold pairs of wings, and become inhabitants of the air
and land. And if any mischance brings them back into
their former element, they are doomed, unless a friendly
grass -stalk provides the means of safety. May-flies,
dragon-flies, gnats, and many others are thus adapted
to two regions.

Each region, therefore, is filled with a number of
forms of life. These do not live independently,
however, but are adjusted to each other. We know,
in fact, that if water-fleas are plentiful in a piece of
water, the condition of the fishes will be so much better,
because they form almost the entire food of the young
fishes. We must not forget, moreover, that the plants
in any region are important to the animals contained
in it. This becomes clear at once when we reflect that
it is they that form the nourishment of the plant-eating
animals ; and that they also provide more or less shelter
for the animals, and especially their young, and so
cannot be dispensed with.

Thus each region is a self-contained whole, in which
plants and animals live in mutual relationship, and the
diminishing of one species always reacts on another.
But the foundation of all animal-life is found in the soil,
the distribution of water and land, light and air, and
the climate and other factors that we may call the
physical conditions of the place. The totality of animals
and plants that live under these conditions and are

INTRODUCTION

2 5

dependent on them and on each other, may be called
the “life- commonwealth,” or bioccenosis } Thus there
are “ bioccenoses ” of the pond, the river, the wood, and
so on ; and also biocoenoses of a higher order, such as
the fauna — that is to say, the animal-life — of an entire
country.

We need only consider any single animal in a
bioccenosis to see at once how it is really a member of
a community. Let us, for instance, examine the life
of the fox. For this purpose we must learn how that
crafty thief obtains his prey. But this implies further
that we cast a glance at the life of the animals he preys
on ; we must consider the speed of the mice in order
to appreciate the leap of the pursuing fox ; we must
know something about the hearing of the hare, to
understand how reynard can creep up to his victim
without being perceived. There is an old illustration 2
of the interesting mutual relations of fox and hare,
which shows very well how two species react on each
other in their condition. If we suppose that the hares
increase in any region that contains only these two
kinds of animals, the result will be that the foxes will
multiply in the same district, because the abundance
of food will make them stronger, and able to rear a
larger number of young. But the increase in the
number of foxes will require an increase in the quantity
of food ; the hares will be less able to escape from

1 This term was first used by Mobius, of Berlin, and was afterwards
extended and modified by Hensen and Dahl. Hensen insisted on the
statistical method as most important in the study of bioccenoses, so as
to discriminate between the normal and the accidental.

2 The instance is taken from Darwin.

26 DARWINISM AND THE PROBLEMS OF LIFE

their numerous enemies, and will be decimated. When
the foxes find less to eat, they will decrease again, and
give more chance to the hares, and thus the balance of
vital advantage will oscillate between the two species.
This will bring about in time an unstable equilibrium :
that is to say, the number of the two species will be
constantly rising or falling a little above or below a
certain level, but will remain at the steady average.

In reality the situation is rather more complicated,
as the fox does not live on hares only, and the hare has
other enemies besides the fox. But the fact remains
that there is this correlation between the animals of
a certain region ; and it must be so, otherwise a species
would increase indefinitely.

Let us suppose that a couple of foxes were left
to multiply in peace. As a rule the fox has four or
five young ones, and this for several years in succession.
But we will take a case in which a couple bring six young
ones into the world once for all ; and suppose that three
of these are male and three female, and that these three
couples have each six young in the following year, so
that there are then nine pairs, and so on. In ten years
the number of foxes would have grown to 118,098, and
this number would be much greater if each couple cast
young more than once, as is the case in real life.

As a rule, however, the animal population of a
district remains constant, apart from the interference
of extraordinary agencies. If, therefore, each of the
couples of foxes in a given wood have five young every
year, and this for seven years, or thirty-five in all, it
follows that, if the number of foxes is to remain steady,

INTRODUCTION

27

thirty-three must die, and only two remain to replace
the parents.

It is just the same with all animals and plants.
Everywhere there are far more born into the world
than can be supported. Take an apple-tree in blossom.
If a fresh tree were born of every flower, there would
soon be nothing but apple-trees on the earth. But
besides the fruit-trees there are myriads of other plants,
and each of these has an immense progeny. The
earth is not large enough to hold this vast wealth ;
every corner of it is already occupied. Thus it is
clear that over-production in Nature creates an infinity
of life only to destroy it.

We may, of course, admire the “inexhaustible riches”
of Nature, but on the other hand we must shudder at
the tragedy of millions and millions of living things
coming into the world only to die, because there is no
room for them. However, they all have an unconquer-
able lust for life, and are impelled by it to fight with
all their strength for space with those that already occupy
it. Thus there is bound to be an endless strife in
Nature. It is the “wealth of Nature” that occasions
the pitiless, ghastly, despairing struggle, and converts
the earth into a reeking battle-field.

However, we will not regard Nature, so cold and
pitiless, with the warm feeling of a human heart. We
will seek to detect the causes that lie at the bottom of
the facts.

Darwin explained to us the over-production of Nature,
by showing how large the posterity of this or that living
thing would be. All animals by no means increase at

28

DARWINISM AND THE PROBLEMS OF LIFB

the same rate. While the fox has, on the average, four
or five young in a year, the hare has eight to ten young
yearly, in about five casts, and the mouse as many as
thirty. These figures are far surpassed by the fishes ;
the carp, for instance, discharges 3,700,000 eggs. But
the highest number is found in intestinal worms. We
learn with astonishment that the maw-worm produces
64,000,000, and the tape- worm 100,000,000, eggs.

If we now cast a glance at the life of these animals,
we find that their fertility is directly related to their
peril. The fox has few enemies, the hare incomparably
more, and the mouse is, so to say, the piece de
resistance of all our flesh-eating animals and birds.
The eggs of fishes are much relished as food by many
aquatic animals, and the sluggish, defenceless carp only
too often falls a victim to the predatory fishes. Much
nimbler is the trout, which has also less enemies to
fear in its stream, and so only produces 600 eggs
a year.

But there are other agencies besides enemies that
decimate a species. The young foxes pass their early
days in a warm and sheltering structure ; much worse
is the lot of the hares, which are laid on the bare
ground, so that the first arrivals, in the middle of
March, nearly always perish ; and the ova of fishes
are exposed to all kinds of accidents, as they are
very easily washed away or dried up. Remember, too,
the difficulties that the egg of the cattle tape-worm
encounters before it can become itself a sexually mature
animal ! First it has to be ejected in the human
faeces, and then it must be licked up by a cow, in the

INTRODUCTION

29

bowels of which it develops into a young animal.
This passes into the muscles, and buries itself therein.
Then the cow must be killed, and its flesh be eaten
by a human being, for it is only in the human intestines
that the tiny creature will grow into the adult tape-
worm. We can easily see that the tape-worm would
soon become extinct if it were less fruitful.

We might go through the whole series of animals,
and we should find in every species a confirmation of
the fact that every animal’s fertility is proportionate
to its perils. We may add that it is also proportionate
to the food and space provided for it, since it is clear
that, if foxes multiplied as mice do, they would soon
consume all the animal food in their environment, and
would be doomed themselves ; whereas vegetarian
animals, for instance, would find a far more abundant
diet. It is also obvious that animals with a limited
habitat must have a low degree of fertility, otherwise
they deprive themselves of food, light, and space, and
court destruction.

We shall explain at a later stage the fact that each
species produces, on the average, just as many young
as is necessary for its maintenance, and that, therefore,
its production increases in proportion to the dangers
it encounters. Here we need only observe that every
animal has in itself the power of multiplying in-
definitely. Thus is brought about the struggle for life,
the unceasing fight for food, space, and light.

This struggle only affects the number of organisms.
It restrains each species within the limits that are set
to its expansion. But there is another struggle for

3 °

DARWINISM AND THE PROBLEMS OF LIFE

life, the more important one which Darwin immortal-
ised his name by discovering. It takes place between
members of the same species, and consists less in an
active conflict with a recognised enemy than in an
unconscious effort at self-maintenance. In this struggle
the best equipped is the victor. Hence Herbert
Spencer’s phrase, “the survival of the fittest,” is
preferable to “ the struggle for life.”

When the foxes in a particular locality are especially
menacing to the hares, the first of the latter to be
eaten are those that are slower than their companions,
or less able to perceive their enemies in time owing
to defective hearing or smell. The better equipped
hares survive longer, and so are able to bring a more
numerous progeny into the world. But since, as we
know, the parents transmit their qualities to their
offspring, the new generation of hares will be equally
conspicuous for speed and sharp senses, if it comes
entirely from the finer hares. If there are amongst
the new-comers animals that fall considerably below
the average, they will be the first victims to the foxes,
and leave no offspring. However, this does not go
on until all the hares are so equipped that no fox can
master them. Among the foxes themselves it is always
the individuals that can catch the improved hares that
survive, secure the most food, and so leave a larger
progeny. Thus the sluggards gradually die out
amongst the foxes as well, and only those survive
that can capture the quicker hares. This must be met
by a new selection among the hares, only those
surviving and reproducing that are better equipped

INTRODUCTION

31

than their parents ; and thus we get a further advance
of the good qualities of the hare, which grows on and
on, without end, because there is a corresponding
advance in the animals that have caused the improve-
ment — in this case, the foxes. Darwin has shown
from the example of “ artificial selection ” — selection
by the hand of man — that such an improvement in
the characteristics of an animal can probably be brought
about by “natural selection.”

Breeders have succeeded, not only in increasing those
characteristics of domestic animals which they wish
to accentuate, but even in producing new ones, and
so in converting an animal gradually into one of a
quite different appearance. When we look at the
races of pigeons to-day, it is easy to believe that we
have before us quite different and independently
originating species. As a fact, some races of pigeons
differ from each other more than the pine-marten from
the stone-marten. What a difference there is in the
various parts of the body between pigeons ! The beak
of the turbit, for instance, is hardly visible, while the
“ carrier * has a long beak with the most curious growth
hanging from it. In many kinds the feet are clothed with
very thick plumage, in others they are quite bare. And
then there are the infinite diversities of colouring !

We find just the same if we take other illustrations.
Look at the difference between a pug and a grey-
hound, or an English race - horse and a Belgian
draught-horse! It is the same with cattle and pigs.
In every case we find races that differ most profoundly
from each other.

32

DARWINISM AND THE PROBLEMS OF LIFE

Now, all these different races are not originally
independent. It is man who has taken a few primitive
types and changed them by selection. In the case of
the pigeon it is certain that all the various races descend
from one primitive form, the rock pigeon, which is
distinguished by black bands on the wings. We see
how these modifications can be brought about in the
actions of breeders, who are always bringing out new
races. They do not accomplish this by crossing ; no
new characteristics can be produced in that way, but
only the existing ones mixed and distributed. Breeders
act otherwise. They select from the offspring of a
couple the animal that shows a slight trace of the
feature that they wish to produce. Thus, if they desire
to create a race of dogs with long legs (and there are
prizes offered by breeding societies for such objects),
they choose one pup from the litter that has longer legs
than its brothers and sisters. This is paired with a dog
from another litter with specially long legs, and the
same selection is made again amongst their pups. This
is continued until they get a race of dogs with legs of
the required length. The object is attained by the
accumulation of insignificantly small variations.

According to Darwin, Nature acts in this way, only
on a higher scale. It selects, not only in the interest
of one characteristic, but of a number simultaneously.
So in the case of the hares, to return to our illustration,
it is not merely a question of making them swifter than
their enemies, but also of furnishing them with sharp
senses, and a higher intelligence to use in choosing
places of security. Finally, they must have no con-

INTRODUCTION

49

our own children. How fine it is to watch him in his
splendid flight !

This “ American ” habit of looking only to the useful
is odious, and unworthy of a poetic and imaginative
race. We regard with pleasure the re-birth of the
historical sense the increasing regard for monuments
of former days. Let us take care, then, to preserve
the animals that are as much connected with the
poetry and feeling of our race as historical reminiscences.

We may now ask how it is that man is able to
extinguish whole species of animals, a thing which no
other animal can do?

It is not so much by powder and shot, not so much
by snaring and poisoning, as^>y the changes he makes
in the country. In spite of all snares the number of
foxes increases steadily in the Black Forest, because
it is impossible to dig up their homes in the rocks.
The field-mouse has not diminished in spite of all
attacks; neither has the lark, though the Italians bring
them down in swarms.

It is civilisation alone that changes the fauna of a
country. If our forests were not cleared, and our
marshes not dried up, the dry branches would still
snap under the tread of the bison and the elk, and
the wolf would still threaten the flocks. Modern
forestry is slowly but surely destroying the wealth
of bird-life, as the thinning of the trees and the brush
deprives the birds of their nesting-places. It is not
cats, or weasels, or foxes, but the disappearance of
the thick bushes, that is robbing us of the song of
the nightingale. This has been recognised of late

D

50

DARWINISM AND THE PROBLEMS OF LIFE

years, and efforts have been made to plant thickets
alongside the railway on some of the less converted
estates. In connection with one of these experiments
in Thuringia nests have been found on an average
every thirty yards, which is a decided success when
we consider the dislike of the birds for new plantations.
However, the times will not wait; cultivated land is
changing its appearance more and more, and our
old friends are disappearing. Few of them can adapt
themselves to the new conditions, like the black-bird,
which is gradually becoming a town-bird, and now
pours out its song from the roof of a house or even
the chimney of a factory, instead of from the top
of a rain-dewed tree.

Other birds are not deprived of their nesting places
in the advance of civilisation ; some, in fact, find them
in greater abundance. The chaffinch, which nests on
trees, is never at a loss for a spot, and we hear its
jubilant cry the most frequently of all. The spread
of the fields gives more room for nesting to the lark,
which is also on the increase. This is an excellent
proof of the correctness of what I said, since its nest
lies in the ground, exposed to innumerable enemies.

But most birds, especially our best singers, breed
in the bush, and they are steadily diminishing owing
to the destruction of their nesting-places. And the
same is happening to the fishes.

The rivers are controlled, and the standing waters,
in which the inhabitants like to lay their spawn, are
disappearing. The Rhine-salmon comes less and less
frequently up-stream, and if it were not for the partial

INTRODUCTION

51

remedy of artificial breeding - places, it would have
vanished from our tables long ago. The Thames
has long been deserted.

We can understand now how it is that civilisation
acts in this way on animal-life. We saw, in considering
regions and biocoenoses, that physical conditions form
the essential foundation of an animal-world. But these
are altered by civilisation, and thus we realise once
more how fundamental the idea of bioccenosis is.

What can we do in face of this increasing devastation
of the country?

Is a time coming when our forests will again have
luxuriant under-wood, in spite of the reduction in the
output of timber ? Possibly. But it seems more
likely that civilisation will crush Nature under its iron
feet ; that the days are approaching when the
nightingale and the robin will be legendary shapes
in a remote past. Perhaps in those days there will
be a race on the earth that will tell, with a pitying
smile, how there were once human beings whose
heart was more stirred by the song of an unseen
bird than by the music of artificial automata.

CHAPTER II

MAMMALS

Life of mammals. Protective value of colour. Origin of colour.
Hibernation. Store-rooms. Increased production or diminished
peril of destruction. Why mammals do not multiply more.
The play of animals. Explanation of play by rest and the
accumulation of energy. Human play. Imitation in play.
Explanation of instinct. Instinct and intelligence. Exercise of
the mind in the games of children. Pleasure in play. Conscious
self-deception, imagination. Play and art. The animal is at the
threshold of art. Sense of freedom in play. Games of children.
Attention. The use of curiosity. The mind of the animal and
of man.

Every friend of Nature, everyone who is acquainted
with the life of the forest and the field, knows that
there are not too many mammals that now meet the
eye of the traveller.

Many a time during a walk through the wood do we
see something hopping about here and there, and find
on drawing nearer that a squirrel is hurrying with
nimble springs to the nearest tree, and climbing up it
on the side furthest away from us. Now and again we
discover a hedgehog in his leafy hiding-place, or stand
by a pond to watch the antics of the water-shrew or
the water-rat. If fortune favours us, and we keep quite
still, we may see the field-mouse hurrying over the
stubble

5 2

MAMMALS

53

It is still better in the evening. Then the lover of
Nature takes his place at the edge of the wood with
a telescope or glass. There is a rustle in the bush,
and a hare springs swiftly into the meadow, looks
round, and, if all is quiet, hops farther on. A louder
rustle, and deer come slowly out, to enjoy the succulent
green or to regale themselves on the toothsome pasture
of the nearest clover-field.

But the attentive observer learns a good deal about
animals without seeing them. Here the bark stripped
from a slender twig in the thicket betrays the proximity
of a strong buck ; there he notices the much - trodden
haunt of the slender deer. On all sides he sees in-
dications of the presence of plenty of mammals ; in
the winter, especially, he reads whole stories in the
footsteps that stand out in the snow.

Over a broad snow-sheet runs the trace of a hare.
It can be seen for a long way in an ever curving line.
Then it is joined by the track of a second hare, though
the two are distinct. Now there is a trodden spot in
the snow that catches the eye with its drops of blood
and scattered wool ; it is the wooing or bucking-place
of the long-eared game. We look again, and see other
steps approaching ; a fox has crept up to the timid
animals. Now there is a deep pit in the disordered
snow, its pure white flecked with blood. Reynard’s
stratagem has succeeded. He has got his dinner.

The life of all our mammals is surrounded by constant
dangers. Some of them, in particular, have been
subjected to so sharp a selection by the unceasing peril
that only the finest can survive the struggle. Thus,

54 DARWINISM AND THE PROBLEMS OF LIFE

for instance, the wolf has become so cautious that
he often escapes from the most careful traps. The

endless attacks upon this dreaded robber have left only
particularly cunning specimens in existence.

As a general rule the day’s work of our mammals is
very monotonous. Brehm has compared it, in his
striking way, with that of the birds. The mammals
are, he says, not such light-livers as the birds. They
have not the liveliness and the unquenchable joyousness
of the lovers of the light ; though they have a certain
comfort and enjoyment of life. Except in their early
youth they refrain from useless exercise of their bodily
strength. For the bird, on the contrary, to live is to
move and to move is to live. The bird is never at rest,
and would like to turn the whole night into day. Its
little heart beats more quickly, its limbs are more
elastic, more wiry, than is the case with the mammals.
The mammal seems only to experience real joy in life
when it has packed itself away as comfortably as
possible, to sleep, or at least to doze. The bird is a
thing of movement ; the mammal, of sensation.

This is quite borne out by their organisation.
The mammal, even when it can attain great speed, is
tied to the ground, and cannot move anything like so
independently as the earth-free bird, which can easily
outstrip our swiftest expresses. So it is with most of
the arts of movement. What mammal can vie with
the nut-hatch in climbing, as it runs, head downwards,
up the trunk? Nor are birds backward sometimes at
swimming and diving.

But now for the other side of the matter. How

MAMMALS

55

much the birds are surpassed by the mammals in the
life of feeling ! The senses themselves are, with the
exception of sight, constructed quite differently in the
two classes. Think, for instance, of the sense of touch
in the whiskers of the cat, and the sensitiveness of our
finger-tips. Think of the sense of taste, which is
almost entirely lacking in the bird, and the extra-
ordinarily fine scent of the dog, which recognises the
track of its master amongst a thousand. Even hearing
is far more advanced in the mammal than in the bird,
though it has, for the most part, no appreciation of
music ; but we know that the musical ear has more
difficulty in detecting faint sounds than the unmusical.

The intelligence of the mammal has been developed
along with its senses. A great advance in this is so
peculiar to them that we might almost call it a
characteristic of the whole class.

However, even the keenest intelligence would not
protect our quadrupeds from destruction, if they were
not provided by Nature with other means of escaping.
It is their colour, especially, that causes their enemies
to overlook them. The hunter often finds that he will
pass within three yards of a hare in its bed without
seeing it. And how difficult it is for the unpractised
eye to distinguish a standing doe from the trees of the
forest.

Tha colour of our mammals varies in all tones of grey
and brown, and this is the colour of the ground. An
animal with a lighter shade would soon catch the eye of
its enemies ; it could not guard against surprises, and
would be doomed. Hence, if a quadruped of a lighter

56

DARWINISM AND THE PROBLEMS OF LIFE

colour were to come from another locality, it would
either be soon destroyed, or those of its offspring would
have most chance of surviving which had most greenish-
brown in their coats. In favourable circumstances the
species might be acted on by natural selection, and
“adapted” more and more, until at last its colour was
in harmony with its environment.

Where other colours are found at the limits of a
country, the animals are affected by these. Our winter
is usually so short that hares are not exposed for too
long a period to attacks through the contrast of their
colour with the snow, besides that the grey tones of the
field and wood rarely disappear. It is otherwise in the
high Alps. Here, during the long winter, a broad
unbroken sheet of snow covers the earth, and a brown
hare could not long escape detection. We can

understand, therefore, why the Alpine hares are white
in winter. In fact, this very species shows clearly how
natural selection modifies an animal. The Alpine hare
is also found further north in the Arctic hare. While it
remains brown throughout the winter in the south of
Sweden, further north it assumes a white coat at this
season. And the further north we go, the longer does
the white coat last, always in proportion to the number
of cold months. In the extreme north, where the snow
never melts, and where no trees break the dazzling
white surface, the Polar hare is white at all seasons, like
almost all the other Arctic animals, the Polar bear, fox,
owl, and so on.

These adaptations to the winter have clearly been
brought about by natural selection. Just as amongst

MAMMALS

57

our animals those that do not grow a thicker coat in
the autumn cannot survive the cold of winter, so among
the Arctic hares those have the best chance of surviving
which had the strongest shade of white when the fur
changed. These favoured ones persisted through most
winters, and so would have the largest progeny. But
in the southern regions it was no advantage to have
a lighter shade at the spring change of the fur ; and on
the other hand, there ought to be no change of colour
when the earth was still clothed in dazzling white. As
natural selection continued its work, a species of hare
was produced in the course of time in which the change
of coat and colour was proportionate to the length of
the winter,, so that the animals were in harmony with
the prevailing tone at each season.

Other animals have different shades of colour at
different seasons. Even the doe has a lighter colour
in summer than in winter, in harmony with the lighter
shade of the green-clothed forest.

Some animals can obtain their food, though often
with great trouble, during the winter, but this is
impossible for others. These would die if they did
not pass the cold period in a long sleep in some warm
spot. It is in the summer only that their diet can
be had.

Our hibernating animals pass the winter in nests
that are completely closed from within, in the hollow
trunks of trees and underneath the ground. There
they need no food ; they fall into a death-like sleep,
and slowly consume their fat. Nature makes this

hunger-cure possible for them by reducing their

58 DARWINISM AND THE PROBLEMS OF LIFE

temperature some 45 degrees (Fahrenheit), and causing
them to breathe ninety times less than usual. With
this diminished vital activity it is superfluous to take
food.

The winter-sleep is not always absolute. Thus the
dormouse or “seven-sleeper” ( Myoxus glis), which has
so appropriate a name since its slumbers last for seven
months, awakens from time to time, and dreamily con-
sumes some of its store of provisions. Others, such as
the hamster, awake in their dwellings as soon as the
ground thaws, but do not open the stopped holes ; they
eat the corn which the hamster especially stores up so
abundantly in its home, that the hamster-catchers of
Thuringia find their chief profit in the grains, which they
clean, dry, and sell as ordinary wheat. Provision-stores
are accumulated by almost all hibernating animals, and
even by some animals that do not really hibernate. The
squirrel stores its food in the clefts of trees, in bushes,
and in holes that it digs, and looks it up in winter.
Nevertheless, a severe winter kills large numbers of
them. Some of their stores are forgotten, others inac-
cessible on account of the snow ; and the enfeebled
animals quickly succumb to their great enemy, the marten,
from which they could save themselves in summer by
their speed, and especially by leaping from the highest
point of the tree, a feat that their pursuer cannot imitate.

For other animals the winter is the time of plenty.
It was noticed long ago that heaps of earth-worms
were stored up in the passages of moles, especially
during severe winters ; they were not dead, but
stupefied in such a way that they could not crawl

MAMMALS

59

away. Formerly, these were regarded as food-stores
for the winter, but it is now thought otherwise. The
mole can catch more worms in winter than he can
eat ; this is all the easier because he can follow the
chase with less exertion during their winter stiffness.
He then stores up the superfluous quantity in these
chambers, which are thus a provision for the summer.
The fact that 1,280 paralysed worms and 18 grubs
were once found in a mole-burrow shows that these
stores may be very considerable.

The winter-sleep enables the adult animals to live
through the cold months without food, but the young
need nourishment if they are to grow ; this is supplied
at first by the breasts of the mother, but her supply
of milk again depends on a rich and abundant diet.
Hence it is that we find the young always making
their appearance at the time when food is most
plentiful, and the pairing - season is fixed earlier or
later to correspond.

Spring is the love-season for only a part of our
quadrupeds. The smaller carnivora, such as the
fitchet- weasel, have it in March, and the fox has his
“rut” in February; the former are pregnant for barely
two months, and the latter two and a half, so that in
both cases the young see the light in May. Other
animals have the pairing-season late in the year, as
is the case with the doe, which bears its young for
forty weeks, and so has its rut in July and August.

Mammals are far from prolific when we compare
them with other classes of animals. But that does
not violate the principle we laid down in the first

6o

DARWINISM AND THE PROBLEMS OF LIFE

chapter, that each animal has the power to multiply
so much that, if there were no hindrance, it would
gradually people the whole earth. Even a species
that has only six young ones in the course of life
would increase to 15,000,000 individuals in 500
years.

We saw that each species bears young in proportion
to its peril, and that in each case the reproduction
is sufficient to maintain the species. We might now
ask whether the rate of reproduction is not increased
by natural selection. It is obvious that amongst the
hares of a particular district it is not only the swiftest
that have to care for progeny, but that those also
which bear more young than others will dominate in
the next generation. If one hare has ten young and
another twelve, is it not more probable that more of
the twelve will survive than of the ten, and that the
survivors of the larger brood will carry on the higher
fertility which they have inherited?

No. The inference is wrong. We know that species
have been put in a position to maintain themselves
by natural selection. In this there are two chief
methods open to selection. Either the multiplication
of the species is increased, cr its perils are diminished.
The effect is just the same in both cases.

In the case of the hares, and in fact of all the
mammals, it is the second method that is chosen.
The animals are cunning and active so as to be able
to avoid many dangers. Above all, the new brood
is protected, especially by finding its shelter and food
inside the mother’s body at first. It is otherwise with

MAMMALS

6i

the fishes. In their case Nature has chosen the first
method. The ova, which cannot save themselves from
accident, are poured into the water, where fate decides
whether any of them will ever reach maturity ; moreover,
the little fishes that issue from them are exposed to all
sorts of dangers at a time when the young mammals are
safe inside the mother’s womb. Hence the fishes must
produce enormous quantities of eggs. But the result is
the same in the long run. Both the mammals and the
fishes have the power of maintaining their kind.

But when the maintenance of the species is secured
in the case of the mammals by reducing the chances of
destruction, the first method is excluded for them. The
fishes may mature large numbers of ova within their
bodies, but only on the understanding that the eggs
are small. If each egg were to attain the size of a fish
inside the mother’s body, the number of them would
have to be very much restricted. Imagine a mother-
hare with fifty young ones in her body ; though even
this number is insignificant in comparison with the fishes.
She would be entirely helpless, would immediately be
devoured, and the capacity of great fertility would die
with her. In particular, the young developing within
her need food, and this would have to be derived from
the blood of the mother, which is vitally necessary for
her own maintenance. Finally, the division of the food
amongst so many would mean less for each of the
young, and therefore a weaker constitution ; they would
be destroyed at once, and thus again the disposition
to high fertility would perish. Think, for instance,
of human twins, or of triplets. If such children were

02

DARWINISM AND THE PROBLEMS OF LIFE

born and reared without proper aid and the control of a
physician, they would hardly survive.

Therefore, mammals cannot multiply more rapidly
because the young developing in the womb need plenty
of nourishment, and the supply is limited in proportion
to the size of the mother. The maintenance of mammal
species is secured by the sheltering of the offspring
from danger, so that in spite of their small number, they
can never be all destroyed ; the fishes or tape- worms are
maintained by bringing forth an enormous quantity of
eggs, so that, though they are helpless against danger,
there is every prospect of enough being preserved out
of so many to carry on the species. But why one
method is chosen in one species, and the other in
another, is a question that we will defer until a later
stage.

Mammals are not only sheltered inside the mother’s
body to begin with, but even for some time after birth
the mother’s eye watches over them unceasingly. They
do not need to exert their own strength yet in the severe
struggle for life. They pass the first weeks of life in
lively play . 1

Play is the activity of the young animal ; it devotes
its whole energy and feeling to it. But even after the
animal has grown up, and the anxieties of life demand
all its faculties, there are times when it remembers its
youth, and indulges once more in play. It is the same
with human beings. Cricket not only amuses the child,
but also provides absorbing interest to adults ; and the

1 The remarks which follow on the play of animals generally follow
the ideas of Professor Groos, who deals thoroughly with the subject in
his “ Play of Animals.”

MAMMALS

63

spirit of invention has devised many other kinds of
games for man’s recreation after fatigue, and to give
him pleasure.

But is it true that recreation is the essence of play ?
Will not the soldier, who has been following the most
fatiguing exercises all day long, turn away from play,
and prefer to refresh his tired frame with sleep ? At
all events, he will not indulge in physical games. At
the most he may join in a game of cards.

We see from this instance that in many cases it is
not the whole man, body and soul, that needs recreation,
but only one of the two elements. The mathematician,
who has been engaged all day in most exacting mental
work, seeks to rest his tired brain in the evening. But
during the whole of the day he has felt a twitching of
the limbs ; his muscular energy has been resting and
accumulating, and now impels him to bodily exercise.
If, therefore, we want to understand the meaning of
play, we must recognise the accumulation of energy as
the first cause of it, rather than the craving for recrea-
tion. This will become perfectly clear if we think of the
games of children, which are the basis of all play. The
child certainly does not play because it has a craving
for recreation ; all its thoughts and actions have the
character of play. Nor would it be more correct to
say that puppies are seeking recreation when they run
and tumble about the whole day long.

It is, therefore, we now believe, an accumulation of
energy that leads to play. Let us consider how this
comes about in the case of man.

The accumulation of energy in man is brought about

64 DARWINISM AND THE PROBLEMS OF LIFE

by the multiplicity of his faculties. He does not need
to use all his powers in the fight for his daily bread.
One man gains his livelihood by manual labour — he
is a mason, an iron-worker, or an acrobat ; another
makes it by mental work — he may be a scholar or a poet.
In others there is an alternation of the two kinds of
activity, but one element always rests and accumulates
energy ; and as the struggle for maintenance does not
require this energy, a man turns to sham-work for an
outlet for it. He will imitate real work : he will play . 1

This manysidedness of faculties in the struggle for
existence distinguishes all the higher animals from the
lower. The energy of the lower animals is entirely
absorbed in the search for food, the avoidance of
enemies, and the preparations for reproduction. It is
otherwise with the bird and the mammal. A successful
raid in the morning will provide a family of foxes with
food for the whole day, and they laugh at danger in
front of their shelter. The warm sun falls on the furry
coats of the sated animals ; the rest has strengthened
their limbs ; and the body, with no serious demands on
it, will, in the absence of real employment, make a
pretence of it . 2 Instead of his real victim, the fox runs
after his brothers and sisters. He plays.

But is it really excess of energy that impels the young

1 This theory, that the essence of play is excess of energy, was first
expounded by Schiller in his letters “On the aesthetic education of
man.” I regret that I have not space to reproduce the beautiful
language of the poet. It is marvellous how many philosophical problems
— problems that seem to be quite modern — Schiller has treated with
felicity. Herbert Spencer has expanded his ideas on play.

2 Spencer joined this idea of pretence or imitation .to Schiller’s
theory of play.

MAMMALS

&5

animal to play ? Will not even a tired puppy dart into
the water after a piece of wood ? Are not kittens sent
over and over again in pursuit of a rolling pebble? Is
it really excess of energy that makes children play ? No.
It is not excess of energy ; a very little energy suffices.
Think of the scholar. He has worked hard all day
with his mind, yet he sits down to play cards in the
evening. Here he is devoting himself again to the
most complicated logical reasoning for the sake of the
game.

How does the second principle stand? Is the game
an imitation of real work, which man longs for, but has
no occasion to do ?

This idea also must be abandoned when we reflect
again on the chief form of play — the play of young
animals. They have no thought whatever of serious
work ; how, then, can they feel a lack of it, and make
a pretence of it ? The young squirrels running unceas-
ingly up and down the tree, the young goats butting
each other with their heads, and so on, are not making
a pretence of doing real work, but are impelled by an
irresistible impulse. All animals have their character-
istic games even when they grow up in isolation, and so
have never seen the real work of their species. A
puppy that is early separated from its mother and
reared artificially will seize and shake the hem of a
coat in its characteristic way, just as a grown-up dog
does with cats, in order to break their necks.

We have at last found the nucleus of play. It is an
impulse that caused it. Even in the games that imitate
the work of the adult, it is an impulse that urges the

66

DARWINISM AND THE PROBLEMS OF LIFE

young animal to imitate. The impulse of imitation is
peculiarly strong in children and young animals. It is
an impulse that their parents have in their young days,
and have transmitted to their children. This impulse is
the same thing as instinct.

But are we justified in speaking of instinct in the
higher animals, and even in man ? Are they not
endowed with reason, and is it not this that controls
their actions ? 1

No. There are instinctive actions even in man. Pass
your hand suddenly before the eye of another, and you
will see the eyelid close immediately, without the
other being conscious of it . 2 This closing of the eye-
lid is called a reflex action, and if we seek to understand
it we must first examine more closely the nerve-tracks
in the body.

There are two kinds of nerves. The first group is
called the sensory nerves ; these are they that pass from
the skin to the brain (and spinal cord), and conduct
thereto every touch from without, every twinge of pain,
and every impression made on the senses. When the
brain has received the impression in this way, it
telegraphs back to the spot whence the message came.
For this it uses the motor nerves, which pass from the
brain to the external surface and the muscles of the

1 Buchner and Brehm attack the idea of instinct generally, but it is
the old idea of Descartes which assigned reason to man alone, and
only credited animals with instinct. They both entirely forget that
there may be other meanings of instinct. Groos draws attention to
this.

8 In what follows I pass over the various theories of instinct, and only
jive the one that has been most accepted of late. This is the theory
of Weismann, and much the most probable.

MAMMALS

67

body. The proper movement is brought about in this
way. In our example the wave of the hand would be
the sense-impression ; this would be conducted by the
sensory nerves to the brain, and from here the closing
of the eyelid would be brought about by means of
the motor nerves.

But the reflex action does not always consist of a
single movement ; often many follow upon a single
impression, and one of these brings about the other.
This is the case, for instance, when we trip over a stone.
The shock to the foot is followed by a whole series
of movements — a stretching of the arms, a throwing
back of the upper part of the body, and several quick
movements of the legs.

Here we have reached the transition to instincts;
these also are characterised by the fact of a number of
movements following upon sense - impression. It is,
therefore, only a complicated reflex action when a
young, untaught kitten springs instinctively after a
mouse as soon as it sees it.

Thus the basis of both reflex and instinctive actions
is corporeal, and is found in the nerve-tracks. And as
all the organs of the body can be affected by natural
selection, it can also bring about changes in the
connections of these tracks and can increase the
sensitiveness of the nerves. When we thus discover
the material groundwork of natural selection, it becomes
clear that instincts are subject to it, and modified by it,
and that new ones may be brought into existence by it.

Anyone who tries to catch a fly with his hand will
see that the little creature is generally off before the

68

DARWINISM AND THE PROBLEMS OF LIFE

hand touches it. Its flight is purely instinctive ; there
cannot be any question of experience, as even the fly
that has just issued from the pupa will act in the same
way. How has this instinct to fly attained such a
perfection ? Most certainly by natural selection, since
those flies survived longest that had it in the highest
degree. Instincts are one of the requisites of an animal’s
life, and they are therefore subject to natural selection.

The life of the lower animals is regulated by instincts.
How complicated these are will be seen when we come
to deal with insects. But, clearly, natural selection
must often favour instinctive action in the higher
animals as well. When the murderous face of the fox
suddenly appears before the resting hare, there is not
much time for reflection ; the best thing for the hare to
do is to spring aside instinctively and make off. But
does the instinct go any farther? Is the hare’s running
away also instinctive, and would that be best for the
hare? Here we must answer no. In running it is
obviously advisable for the animal to reflect. The
hare will fly, double, or drop, according to the distance
of its pursuer ; and this control of the instinct of flight
by the intelligence will certainly be a great advantage
to the animal, so that the development of intelligence is
favoured by natural selection.

Intelligence does more than instinct; it protects the
animal even in unforeseen dangers. If you put a
mole-cricket on a glass plate its instinct makes it try
to bury itself. Intelligence would tell it after a few
attempts that it is impossible to scratch up glass, and
that flight is the better course in such circumstances.

MAMMALS

69

But would not those animals be in the best position
that had intelligence and instinct highly developed?
Will not an animal that makes instinctively for its prey
the moment it sees it, secure its object more speedily
and certainly than another that has to reflect on its
course of action ?

It is true that instincts in connection with food and
escape might be so perfectly developed in mammals
that they would act with absolute precision when they
were needed. There are wasps that perform the most
complicated actions in laying their eggs, yet these are
all purely instinctive, as we shall see in the sixth
chapter. But instincts like these require the most
intricate nerve-tracks.

Let us consider the complicated fashion in which
mammals seize their prey. Who has not seen how a
cat, at the sight of a mouse, steals forward, springs,
thrusts out its paw, seizes its victim, shakes it, and
finally devours it ? What elaborate nerve-tracks would
be required in it, if all this were instinctive ! yet there
are still other habits of the cat. In a word, we see that
if the complicated life of the mammals were effected
solely by instincts, the demands on the nervous system
would be so great as to leave hardly any room for
intelligence.

We have only the two alternatives : either an

advanced intelligence or perfect instincts. In the
mammals it is the former that steadily advances, since,
as we saw, it can do more than instinct. We might
even say that the more sagacious animals are, the more
retrograde are their instincts ; and they are most

7o

DARWINISM AND THE PROBLEMS OF LIFE

backward of all in man. In the human species the
most intelligent races have the least developed instincts.

It is true in all our mammals the intelligence is so far
advanced that their food and flight-instincts can only
be in an imperfect condition. But if the alimentary
instinct is only rudimentary in a mammal, if the whole
of the mechanism that serves for seizing the victim is
only feebly developed, how can the animal capture its
prey from the very beginning? A cat that sees a
mouse for the first time, and has no instinct to tell it
how to catch the creature, will certainly not be able to
do so if it has had no experience in catching mice.
Now we come to the solution of the problem. In the
lower animals actions are regulated by instincts, which
work faultlessly from the very first, according to their
nature. In the higher animals the instincts are feebly
developed, and the actions are regulated by intelligence.
But the intelligence must be trained, like the powers of
movement. For this a certain period is necessary in
which every unsuccessful act will not endanger the life.
This is the period of youth.

The instincts make their appearance, though im-
perfectly, in youth ; that is to say, at a time when the
animal has as yet no serious need of them. During
this period the animal can improve the inherited,
imperfect impulses by its own experience ; and if it is
taken away from the mother and her direction, it knows
how to catch its prey and protect itself, and will acquire
in time the requisite adroitness.

Now, this exercise and training of the faculties takes
place in the play of the young. We can, therefore,

MAMMALS

7 1

realise the immense importance of play. It is the
school in which the animal learns to play its part in the
struggle for life. Without these early gambols the
animal would be clumsy and stupid when it leaves its
mother, and would be quite unfit to meet the stress of
life. The animal must play, and must therefore pass
through a period of youth. Thus we are now in a
position to say that the play is not there because of the
youth, but that a period of sheltered youth has been
provided by Nature for the purpose of play.

Play is, therefore, absolutely necessary for the young
animal. And in order that it may play often, a feeling
of pleasure has to be attached to the exercise. It is
true that the first impulse to play comes from instinct,
which urges the animal to stir itself, especially in
directions that have some relation to later life ; and we
have already seen that the instincts of play are im-
perfectly developed instincts of food-getting, flight, etc.,
which must appear in youth and afford the little one a
means of acquiring the bodily adroitness that it needs.
The exercise of every instinct is pleasant in itself, still
we may legitimately speak of the lust for food, for
fighting, and even for murder, and make use of the
phrase, “to satisfy one’s impulses.” Nevertheless it is
clear that this feeling is much strengthened in play. It
is quite certain that even the most incorrigible brawler
does not feel as much pleasure in his serious fighting
as boys do in their romping. This is even clearer if we
take instincts the serious use of which is never agreeable,
such as flight from an enemy. With what pleasure
children, and even young animals, chase each other

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DARWINISM AND THE PROBLEMS OF LIFE

about ! In fact, there is one experience that shows
clearly that the animal feels most pleasure in the very
form of play which will be of most importance to it
when it becomes reality. The harmless doe is hunted
throughout its whole life ; yet when these animals play
together, we notice that the pursued puts his whole soul
into it while the chaser is very little interested. It is
just the opposite with the carnivores. With these the
chaser is the more spirited. He tastes the whole joy
of hunting, and in fact, the chase will be the chief
purpose of his existence in real life.

What is it, then, that affords the young animal so
much pleasure in play? Not only the young, in fact,
but even the adult, which is often seen to play. What
is the nature of the delightful feeling that play engenders?

It consists, in the first place, of the pleasure that is
felt in all energetic action. Then, it is certainly pleasant
to see that one can do something — that one has power.
In play a man delights to feel that he is “doing some-
thing.” It is from this feeling that the pup is so ready
to tear up boots and other objects ; that the cat rolls
its ball ; that little birds, and often little children, set
up prolonged cries, and take considerable pleasure in
noise.

It is, further, the sense of overcoming difficulties that
adds to the pleasure of play. Swinging, tobogganing,
sliding down smooth surfaces, etc., which children are
so fond of, is a sort of escape from the gravitation of
the earth, and from the friction that makes all movement
difficult. All these movements fill us with a peculiar
sense of freedom.

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73

But play is most advanced in character when the
playing animal is conscious of its pretended activity ;
when it knows it is only playing a part. Play is in
itself only a pretence, since there is no serious occasion
for the exercise of the instinct. We have to learn next,
therefore, if the animal knows that it is only making
pretence.

This cannot be seriously questioned. Every dog
that pretends to bite its companions or master knows
that it is playing. We could give many such instances.
Remember, too, how animals can dissemble : how a dog
that has broken something will pretend to be engrossed
in some action or other, with the most innocent face in
the world. In this consciousness of pretence we have
imagination , or the faculty of taking to be real something
that only exists in idea. In play, therefore, we have a
conscious self-deception.

Here we find ourselves at the threshold of art, and
it will not be without interest to take a peep into this
field.

In art we have a conscious self-deception, and play
and art are intimately connected, as the very words
“ playing the piano,” “playing a drama,” etc., indicate.
The impulse to play is the real source of artistic
activity both in primitive races and in children. Thus
the animal is brought to the very verge of artistic pro-
duction by its delight in pretence. It does not cross the
threshold ; because for real artistic creation the aim to
influence others by one’s make-believe is necessary.
This purpose is not present in normal play.

The conscious self-deception in play and art is due to

74 DARWINISM AND THE PROBLEMS OF LIFE

a peculiar division of consciousness. Both man and the
animal know, when they are playing, that it is a pretence,
yet lend themselves to it. We find in other matters a
similar division of consciousness, especially in dreams.
Here we often give ourselves up to the most fantastic
pictures, yet the consciousness of the awakened man
often breaks into them, and recognises they are not
realities. I have often had dreams in which I was
chased by enemies that gained more and more on me.
But instead of feeling pain and anxiety I am assured by
a clear consciousness that it is all a dream, and I sink
peacefully into my dream again, and see my enemies
approaching to kill me. I wonder with interest what
the moment of death will be like, and await the experi-
ment calmly, saying to myself that my life will not really
come to an end in it.

There is a similar duplication of consciousness in
play and the enjoyment of art. We are often quite
absorbed in a drama we are witnessing, and only
brought back to our real selves from time to time
by consciousness. We have the same experience in
examining paintings and sculpture. A sort of false
self is formed in us, full of false feeling, and our
real self sinks into the background. Yet we retain
a sense of reality, a real pleasure in the unreal ; but
it passes into the sphere of the pseudo-self, and lets
itself be borne by that.

But why do we never confuse pretence and reality
in play and in art? Must not our real self recognise
that the pseudo-self is only a make-believe?

Our real self knows, or we ourselves know, that

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75

we are the cause of the phantasm. In this we find
the highest pleasure of play and art. The projecting
ourselves into the unreal is voluntary on our part,
and this feeling of our freedom accompanies us, often
unconsciously, as long as we indulge in the fiction.
The reality, on the contrary, presses itself on us
even against our will ; it gives us a feeling of
dependence.

Thus it is the sense of freedom that accounts for
the highest form of pleasure in play and in art. This
sense of freedom gives its peculiar colour to the
world of fancy, and consequently “in conscious play
the whole pretence of action is converted by the
accompanying sense of freedom into something higher,
finer, and lighter, which we cannot confuse with the
reality of things.”

In play we feel ourselves really free. We do just
what we wish to do, and we know that we can halt
and abandon the play at any moment we desire.
We do not feel ourselves to be a link in the pitiless
chain of cause and effect ; we seem to have escaped
from inexorable necessity.

All these feelings are found in a rudimentary state
in the playing animal. Now that we have learned
the cause and the meaning of play, we will recall the
chief forms of the play of animals.

The animal plays on the first day of its existence.
The stretching of its limbs, the gnawing of objects,
the rolling about, are nothing but play, with the object
of teaching the young one to gain control of its own
body. And the young animal not only learns to master

7& DARWINISM AND THE PROBLEMS OF LIFE

itself in play, but also to control its environment.
It learns to appreciate distances, for instance; we see
the same in our infants who have to learn gradually
that the moon, towards which they reach out their
little hands, is unattainable. It has even been said
that a human infant learns as much in its first year
as in all the others put together ; hence the impor-
tance of this “experimental play.” In this play the
psychological factor is the joy of “ doing something ” ;
this is seen most clearly in the destructive tendency
of young animals, and in their delight in making a noise.

When the suppleness of the little one increases, and it
has learned to control its own frame, the play of move-
ment begins. These serve to give the animal the

mobility that it will need in the struggle for life.
Naturally, in this play the particular movements will be
practised which the animal will find useful later on.
The squirrel leaps into the air with the most break-neck
springs ; the marten is equally bent on testing its leaping
powers. Aquatic animals practise swimming ; animals
that live in the air take to flying. Even the buck-
jumping of the kid, which seems to be mere reckless
delight, has its meaning. On the level ground these
leaps are puzzling enough ; but on the mountain, the real
home of the goat, it is quite indispensable for reaching
the higher rocks.

With the play of movement is connected the pretence
of hunting. The carnivores practise this in order to
creep up to and capture their prey ; and the plant-eaters
must learn to escape them. Thus the kitten plays with
the mouse, and learns, by a method that is repulsive to

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77

us, the way its victim runs, so that it can catch them
itself when they run free before it, and the mother is not
present to paralyse them. Deer chase each other for
hours, and so learn to escape when there is serious
occasion ; young foxes catch each other and duck to
avoid each other in front of the den, just as they will do
afterwards with the unsuspecting hare.

Then come the fighting-games of the young male.
These have to make the animals strong and supple, in
order to beat their rivals in the love-conflict later on.
The joyous feeling of strength and power may lead in
this to a frightful mauling of the weaker.

As we saw, the first impulse to all these games comes
from instinct. But there is another element that may
cause the animals to play — the passion for imitating.
This also is an instinct. We see this at once when we
look to the fact that every animal confines its imitation
to its own species. The young fox never tries to imitate
the bird in flying, but imitates its mother in trying to
capture it. We might draw up a special category of
“imitation-games.” In these the young show what they
can do ; they delight in showing that “ they can do it
also,” and strive “to do it better.”

The passion for imitation is an impulse that has
arisen and is fostered by natural selection, like every
other instinct. It leads the animal to learn quickly
what it will need in later life, and so to make experi-
ments on its own account. A flock of game will escape
easier if it follows unhesitatingly a leader that has
scented an enemy, than if each has first to convince
itself that flight is necessary.

78 DARWINISM AND THE PROBLEMS OF LIFE

There is another matter of great importance to animals,
and must be practised in youth — attention.

This is indispensable for every animal. How could
an inattentive animal escape its enemy, or how would
a carnivore discover and catch its prey without this
quality ! The cat watches with the most strained
attention before the mouse - hole. It sits crouched
waiting for the appearance of its victim, all its muscles
ready for the unfailing spring and the joint stroke ot
the paws.

When there is no serious occasion for attention,
and it is practised in play, as it were, we call it
“curiosity.” We see this often enough in animals.
The essence of it is that the animal sees a strange
object, and wants to learn what it is. Often enough
an excessive curiosity leads to the death of the
observer ; it is well known that one can frequently
draw quite close to a marten on a tree and shoot it
without it making an attempt to escape, owing to
its curiosity at the unusual appearance. Generally,
however, curiosity is an impulse of great service to
an animal. It is from curiosity that the young animal
familiarises itself with its environment, and learns
to distinguish between what is good and what is
injurious.

We might instance quite a number of other kinds
of play, but will bring the discussion to a close. We
have, in particular, made no mention of a whole large
division — love-play. This, however, is not properly

play, because it does not serve for the animal to
practise some serious future activity, but is a serious

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79

activity itself; it is only the psychological factor, the
joy of power, that often makes its appearance in it,
that justifies one in speaking of it as a species of
play. We shall see something about its nature in
the next chapter.

In pursuing at such length these observations on
the play of animals, and taking our cue sometimes
from the life of man, we have not passed the limits
of this work. We have learned that many qualities
of mind that seem to belong to man alone are also
found in the animal. This shows us how untenable
is the opinion of those who think they have found
in man’s mental powers something that distinguishes
the lord of creation essentially from other organisms
— something that makes the descent of man from
other animals impossible. We now know that the
theory of evolution need not stop short at man ; that
even his mind is no obstacle to our admitting his
development from animal ancestors. The mind of
man does not differ from that of other animals in
kind but only in degree, and there is nothing to
prevent us from supposing that it has been raised
from the animal level by natural selection to its
present altitude. Just as Copernicus smote the
conceited belief out of humanity that their kingdom, the
earth, was the centre of the world, so Darwin has
put an end to their assumption that they occupy an
exceptional position on our planet. The earth is a
stage of a part of the eternal, everchanging world-mass ;
humanity is a phase of a part of the ever-advancing
world of organic life.

CHAPTER III

BIRDS

Sexual selection. Choice of females. Rejection of the hypothesis.
Advance of the male’s senses. Selection of the strongest suitor.
Explanation of coyness and the animal coquette. Female
selection inadmissible. The love - dance. Selection of the
apparent strongest. Colours as means of distinguishing species.
Use of sounds. Pairing - calls. Origin and forms of song.
Instrumental music of the birds. Migration. Speed of flight. Do
birds tire ? The adaptations of the bird-body. Height of the
migration - flight. Origin of birds of passage. Their strength,
their power of presentiment. Routes of migrating birds. Their
memory and sense of direction. Travelling in flocks.

The poets have often introduced the song of the
bird — as Shelley did — amongst their throbbing lines
over the destiny of men. It is natural that the poets
should love the birds. From the bird the art that man
must slowly learn seems to pour out in rich, inex-
haustible flood. The woods and the meadows are
enlivened by the songs of the birds. Where would
the magic of spring be if there were no singers to
proclaim its glory to us ?

We often read in books of travel in distant lands
that all the splendour of the tropics only awakes a
longing for our own forests because there is no sweet
song in the glittering birds that complete the fair
picture of Nature. Even in Japan, where noble forests

BIRDS

8 I

grow like those of Europe, the traveller seems to find
something wanting. For a long time he cannot tell
what it is, until at last it dawns on him that it is the
stirring song of our birds. 1

But it is not the song alone that makes us love the
birds. To know a bird’s nest and watch daily the care
of the parents for their helpless young is a source of
purest joy to our children. The birds are not far
removed from children, and resemble them especially
in their liveliness and their unfailing spirits. They
seem not only to understand art, but to have also the
nature of the artist.

Hence it is that painters feel themselves akin to the
birds. A man died in Heligoland in 1897 who had
seen the island for the first time as an artist of twenty-
three, and was so enchanted with the bird-life circling
high above, that he devoted himself entirely to the
study of birds. We shall have much to say of this
Heinrich Gatke by-and-by.

But is not that which gives us pleasure likely to
prove dangerous to the birds themselves? It is true
that the inhabitants of the air are secured from many
enemies by their rapid flight and their great agility.
But does not their song bring them to the notice of
marauders ? We know that many birds have light
shades of colour, and these are conspicuous against the
background, and must betray their possessor from afar.
How could such a shade be brought about by natural
selection ? And when we see that, as a rule, only the
males are brightly coloured, we have a new problem.

So I have heard from many who have travelled in Japan.

82 DARWINISM AND THE PROBLEMS OF LIFE

How could natural selection lead to a different colouring
of the two sexes ?

Darwin put these questions long ago, and as an
answer to them he framed his theory of sexual
selection as the second great agency in the formation
of species. We shall understand this best if we compare
it with natural selection.

Both by natural and sexual selection certain animals
have a better prospect than others of leaving offspring
and so preserving their species in the next generation.
In the one case it is those animals that have been
able to escape destruction longest, thus reaching the
period of reproduction, while the others die off before
it comes. In the second case it is the males (sexual
selection affects only the one sex) that attain to union
with a female, as many of them can never reach love,
and therefore never reproduce. Natural selection,
therefore, determines which animals will reach the
period of reproduction ; and among the selected males
sexual selection then chooses those that are actually
to reproduce. In the one case the “bad” are
destroyed ; in the other case they are condemned
to sterility. In both cases their kind perishes with
them.

Thus in natural and sexual selection a few are
chosen out of a large number of animals. This is
possible for natural selection because more animals
are produced than can live ; in sexual selection also
choice is only possible if the males are so numerous
that there are not enough females for all, and some
must go without. As a fact, we do find this pre-

BIRDS

83

ponderance of males in Nature , even man is no
exception to the rule, because there are more boys
born than girls every year. If the females are in
the majority in later life, that is because the males
are at all periods of life exposed to a higher mortality . 1

Which males, then, are selected ?

According to Darwin, there is a double struggle
for the opportunity to reproduce. In the first the
males fight actively for the possession of the females ;
the stronger drive away the weaker, the better armed
conquer the weaponless. In this way, for instance,
the cock’s spurs and the stag’s antlers would be
explained by selection. In the second form of selection
the males are chosen by the females. These are
supposed not to listen to every suitor, but to choose
the one that pleases them most. Thus the bullfinches,
for instance, may once have been the same colour
in both sexes. Then variations occurred in the males,
which showed a shade of red in the breast. This
pleased the females, and the continuous selection of
the redder ones led to the endowment of the male
bullfinches with the bright red breast they now have.

The first kind of sexual selection is based on well-
known facts, and has never been seriously called
into question from the Darwinian side ; it is really
a special case of natural selection. But the second
category has a number of opponents, among whom
we find the distinguished naturalist, Dr. A. R. Wallace.

1 In later years the unhealthy life led by men is to blame for this,
monotonous labour without regard to the body, and the use of alcohol
and tobacco.

I

84 DARWINISM AND THE PROBLEMS OF LIFE

This is intelligible enough. Compare this kind of
sexual selection with natural selection. In the latter
the idea that there must be selection starts from a
fact. In the theory, for instance, that the white hares
have been developed from darker ones by natural
selection, the fact we start from is that white hares
show less against the snow than dark ones ; from this
we are justified in concluding that the lighter the hares
were, the better their chance of escaping the notice of
their enemies. But the man who infers from the fact
that our actual bullfinches have a red breast, that the
female had from the first a preference for red, and was
pleased with the increase of colour, is building his theory,
not on a well-known fact, but on a hypothesis once more.
Our explanation is simple enough, if we say : The bull-
finch has a red breast, and consequently the females
must have always had a preference for red, while the
blue-throated warblers had a preference for blue. But
the inference is not scientific, or at least not until we
have explained why the bullfinch prefers red and other
animals other colours ; and this we cannot do.

Could we not say that the bullfinch got its red
variation by chance, and that it was not exactly the
colour, but “ the stimulus of novelty,” that acted on the
females ? But we must not extend this principle, which
we only know in the life of human beings, to animals,
especially to those only where we find it convenient.
The breast of the male bullfinch, which is supposed to
have been grey, must have shown tendencies to all
kinds of colours, and if the novelty was appreciated by
the females, one would have chosen one colour, another

BIRDS 85

a different one. There would not have been a develop-
ment of the colour of the breast in one steady direction,
namely, towards a bright red. If we suppose that only
one special novelty pleased, and gave equal pleasure to
all the females, we are doing violence to Nature. We
must first show that this novelty pleases the female, and
why it does so.

We see, then, that this second kind of sexual selection
is not satisfactory. How, in that case, can we explain
the peculiar characters of the male ? What was the
origin of the brighter colours, the specially developed
feathers, dances, songs, and perfumes, of the males, in all
classes of animals ? Can we not give a satisfactory
explanation of some of them ? We shall see.

But must we reject altogether this choice on the part
of the females? Is it not blind chance that brings any
male to a female and provides it with the fruit of love ?

No, certainly not. It is not chance that brings the
male to the object of its love. It seeks it of itself.
But it is clear that the males which detect the females
soonest will attain their purpose first, and that those
with inferior organs of detection will come too late, and
lose the reward. Thus we see at once that there is a
sexual selection which falls into the first category of
that group, and enables us to understand how the males
of many animals have better sight, hearing, and smell,
than the females. These organs must, of course, have
been formed and developed by natural selection, since
the animals need them for vital purposes ; but sexual
selection will improve them, as it comes after natural
i selection and is more exacting. It is, for instance,

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DARWINISM AND THE PROBLEMS OF LIFE

certainly more difficult for a cockchafer to discover
a female of its own kind than the masses of food about
it. We understand at once, therefore, why, as a fact,
the male cockchafer has a finer scent than the female,
and why he has special olfactory organs on his antennae
which can be seen externally from their comb-shape.
We find similar structures in other insects, especially
several species of butterflies, and in small crabs
in fact, they are common in the animal world.
Other sense - organs also have been enhanced in the
male sex clearly by the same process of sexual selection.
Many male insects have much larger eyes than their
females, such as the May-flies and the male bees, the
drones. We can see the meaning of the large eyes in
the forehead of the latter. Of the many drones that
follow the one queen in its nuptial flight, one will be
particularly favoured in being able to follow the form of
the queen as she floats in the blue air, and so catches it.

But it often happens that the males lose the fruit of
love when they have tracked the female. When other
suitors come on the scene they will hardly withdraw
resignedly when they see the place occupied ; they
will try to make good their lateness by force, and drive
away their rivals. A struggle of this kind for the
female often takes place, and the victory naturally goes
to the strongest and cleverest. On this principle the
stronger males are again selected, and thus we can see
why the black-cock or the common cock is so much
stronger than the hen. In fact, this kind of selection
may lead to the formation of “weapons,” such as the
cock’s spurs or the stag’s horns. In the latter case

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the animals with the hardest skulls would win at first,
and an ever-increasing horn may have been developed
from the growths on the bones of the head which were
casually produced by the butting. However it may be
with these special cases, there is nothing to be said
against the general principle.

We have, therefore, given a natural and satisfactory
explanation of part of the masculine characteristics.
What are we to do with the rest ?

The black-cock becomes so intoxicated with its dance
on the branch of a tree that, though usually so timid,
it cannot perceive the approach of its enemies. This
dancing - instinct cannot be due to natural selection, it
is obvious, since it is injurious to the animal. But
sexual selection may at least have produced it in the
beginning, and then the second principle would come
into effect. The pairing of the cock has reached such
a pitch because the hen always gave the preference to
the best dancer.

As we have rejected this theory, must we despair of
giving a scientific explanation of the love-dance.

There are experts who will not admit a conscious
choice on the part of the females, but have sought to
replace it by unconscious preference ; in the sense that
each female would yield itself to the male by which it
was most stimulated. This stimulation would take the
form of an enchantment or hypnotism, whether it was
caused by the beguiling song or the dazzling splendour
of the male bird. The female would, in a sense, lose
consciousness from the enchantment, and its resistance
to the caresses of the male would be broken.

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DARWINISM AND THE PROBLEMS OF LIFE

But why does the female sex show resistance at all
to love, which ought to be urged with all its force by
Nature as the great maintainer of life? The desire for
love is so irresistibly implanted in every living thing
that a curb is absolutely necessary. It will be easily
understood that too frequent caresses on the part of the
male will not serve their purpose, namely to create
progeny, but will enfeeble the female, and so be
dangerous to the offspring. Hence Nature has raised a
barrier to the onrush of the male sex, and this is the
coyness of the female. When there is a conflict of the
two powerful instincts, coyness and desire, we describe
the female as “coquetting.”

The male has to overcome the coyness of the female,
and for this the colours, perfume, dance, and song are
useful to him ; by the improvement of one or other of
these features a male will be able to ensnare the female
more quickly than his less brilliant fellows. Among the
variations that appeared in the male there were some
that chanced to stimulate the love of the female. In
this sense the “ choice on the part of the female” can be
be better understood, yet it is not an explanation. It
remains a mystery why just this one among many
variations should affect the female — should affect all
females, in fact. Further, we do not see how it could
happen that the character in question should be
developed steadily in a particular direction by the
female’s choice. Is it not just as if the female had
before its mind from the first the image of the complete
male ornamentation, so that, when the first traces
appeared, she helped it along, and only looked to

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ornament in the sense of giving the preference to the
males that came nearest to her ideal ? As a matter
of fact we should, on this theory, have to suppose that
the female felt from the first — consciously or uncon-
sciously — an impulse to a certain end. This end was
the male ornamentation in its full development, and
it would be at length attained by the steady preference
of males that come nearest to the ideal. This
explanation seems arbitrary and unscientific, because
neither experience nor science tells us anything of this
mysterious working for a fixed aim ; and we shall see
in the eleventh chapter that it must be rejected
altogether.

We must seek another explanation of the dance and
song and colouring. Let us deal first with the
dance.

Is the charming of the black-cock really a means of
breaking down the coyness of the female? If it were,
we should have to assume that the cock must convince
itself during or after the dance that its art has been
effective ; and above all, we should have to suppose that
the hen is brought by the dance to look on him with
a sort of enchantment. As a matter of fact, we see
nothing of the kind. The females seem to be quite
indifferent ; in fact, in this particular case of the black-
cock, they are not very near to the male, and he has
to pursue them for some distance after the dance.
Then there is the peacock, whose tail is so much
admired by human beings ; his females seem to be
quite unmoved by it, and go on picking up their food
trivially, however fine he may look. Has anyone ever

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DARWINISM AND THE PROBLEMS OF LIFE

seen a turkey-hen enchanted by the tail and comb of its
mate ? I do not think so.

In the case of the turkey, in fact, the idea forces itself
on us that the male does not dance for the pleasure of
his wives, but from anger and fighting spirit. The
inflated, red-combed cock “ dances ” before human
beings and dogs as well as before his hen.

I believe that we have here the key to all these
“courtship-phenomena.” They are connected with the
fights of the males, and must be explained as serving to
frighten away rivals. In the first place, it is quite clear
that double courtship of a female need not always lead
to fighting. If a male on the quest of love finds a rival
before him that seems so savage and powerful that he
himself would probably come off second, he will
generally not fight, but retire into the background and
look for satisfaction elsewhere.

But it is obviously not necessary that every fearsome-
looking male is particularly strong in point of fact ;
it is enough that he should seem to be so, as the
rivals are then not likely to put it to the test. Means
of frightening others away are not uncommon in the
animal world. A hunted cat makes its fur stand out so
as to seem bigger than it is. We can, in fact, readily
believe that the manes of many animals, such as the
stag, are intended to make the neck seem bigger and
stronger, and so may have been brought about by this
sort of sexual selection . 1

1 Weismann thinks that the lion’s mane is due to the fact that, in
the fights of the males, those had the advantage whose necks were
protected by thicker hair from the teeth of their opponents. This
theory is unsatisfactory. There are many animals with manes that do

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In the formation of the antlers of the stag it is
probable that the fearsomeness played a more important
part than the improvement of them as weapons. It is
clear that the larger the antlers the more formidable the
animal looks. As weapons two sharp spikes on the
head would be more effective, as we see in certain deer
which have such spikes, and bring down every
opponent, even the most powerful sixteen-pointers.

Now let us go a step further. Rival suitors are
driven away not only by an appearance of strength, but
by confidence of approach. Who has not seen many a
little dog frighten away a big cur by attacking boldly ?
Even a man is intimidated by the self-conscious bearing
of another. It will be found throughout the whole
animal world that a reckless onslaught intimidates an
opponent.

A male that has stolen a female and shows by his
manner that it is not advisable to fight with him will
be avoided. He will show this by inflating himself,
uttering terrific cries and running about. Do we not
see this in the turkey-cock? Is it not clear to any
unprejudiced observer that his capering is a roar-dance ?
Do the red -skin braves perform their war-dance to

not bite each other when they fight, such as the stag. My theory, on
the other hand, meets these cases as well. We might also regard as
means of frightening combative rivals the knobs on the face of the
wart-hog, the beards that give a savage appearance to the faces of
many apes, the two teeth that come through the upper lip of the boar,
and are useless in fighting because they bend downwards, the antler-
shaped tentacles of the stag-beetle, which can pinch much less than
the smaller tentacles of the female, and many other kinds of beetles’
tentacles ; possibly also the chirp of the male cricket, and other
features.

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DARWINISM AND THE PROBLEMS OF LIFE

enchant their squaws ? Certainly not. They want to
strike terror into a lurking foe, and they intoxicate
themselves with their own power. The latter is the
psychological element that enters into the dances of
animals, and sets them to “games.” As a fact,
means of frightening and intimidating play a great part
in all fights. Think of the war-cry of the Indians, our
own “ Hurrah,” the terrific painting of the skins of
savages, and the military moustache. It was this that
gave the French warriors their fierce appearance in the
later Middle Ages, and played a great part in the
Thirty Years’ War. It does really give a fiercer
expression to the face, because it draws up the lips at
the corners of the mouth, over the canine teeth ; and,
to compare human with animal features, we may recall
the projecting teeth that were also used for intimidation.
The martial moustache has been retained in the daring
Hungarian cavalry. But however it may suit soldiers,
it does not become the civilian, in whom it forms a
ridiculous contrast to the otherwise modest and funereal
appearance.

In the instances we have given, therefore, it is a
question of selection of the apparently stronger. I
believe that this explains the origin of a good many
masculine characteristics. It may be asked how far my
theory is supported by observation. Certainly, many
facts can be quoted in favour of it, such as the well-
known one that a young black-cock dances very gently
and stealthily when an older one is about.

An intimidating conduct on the part of the male will
have an effect on the female ; it will not only keep away

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other suitors, but will hold the females together. It is
well known that a stag, or even a cock, treats its
dependents roughly, and will not let them break loose.
If, then, a male terrifies the female by its appearance
and conduct, the latter will be less likely to wander away
after forbidden fruit, and will not venture to make too
much resistance to the allurements of the male. Unfor-
tunately, many animals take Nietzsche’s “ little truth
to heart: “You are going to the women? Do not
forget the whip.” Everyone who has had occasion to
observe the love-making of animals in a zoological
garden will have noticed that it is more frequently a
question of being bullied, than of listening tenderly to
the wishes of the male. In fact, amongst human beings
it is chiefly the strength that conquers women ; not
merely strength of body, but the power of thought, of
mind and will — in a word, the strength of the whole
masculine nature. But in the case of man it is usually
a question of choice on the part of the women, and we
must exclude this element in dealing with the animals,
and recognise force alone ; whether this is used actively
for the coercion of the female, or her resistance is broken
down by the mere perception of it.

Can we explain all the masculine characteristics in
this way? Unfortunately, we must admit that we
cannot. Colours present the greatest difficulty. Many
colours, of course, may be for the purpose of scaring
away rivals, such as the red spot over the eye of many
wild-cocks, which gives it a fierce expression and makes
it look larger. In the case of man the masculine dress
at all times is thought to have had its origin in the

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DARWINISM AND THE PROBLEMS OF LIFE

military dress of the particular period ; and this was
certainly not meant to be merely defensive, but also to
make the wearer seem formidable — as, for instance,
skins with animal helmets, waving plumes, etc., or at all
events to give him a greater appearance of strength and
life and boldness, in which bright colours would be
useful. But it is impossible for all the details of the
composition and design of animal colours to have arisen
in this way. It is also inadequate to explain the
undoubted fact that they act as distinguishing characters
of a species. As such they play a great part in the life
of animals ; it is easy to see that those animals will
propagate best which can recognise their kind most
quickly. Perhaps many light colours arose in this way,
and they could be preserved and accentuated in the
male, but not in the female, which absolutely needs a
neutral tint in order to sit unobserved in the neutral-
tinted nest or on the ground. Only in this way could
the mother and her eggs, and later the helpless young
ones, escape the fatal eye of their enemies. The eggs
of birds that hatch on open nests are also protected by
fitting colours that save them from many eyes ; while
birds that sit in hollows generally have white eggs.
There is an exception in a number of blue eggs that are
found in open nests. An attempt has been made
recently to explain their colour on the theory that the
blue is particularly favourable to metabolism.

There are many features that are common to both
sexes. These are usually confined to particular spots,
and can do no injury to the animal when it sits quietly.
In this group we have a whole series of colours that

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95

are found in the wing-feathers of birds, and are only
exposed during flight. It is the same with colours
in the tail, which only meet the eye when it is spread.

Brighter colours are, as a rule, not found on the
upper parts of females, but may be developed in the
male; because even if they carry destruction to many
of them, the species is in no danger, as the males
are always in excess.

But, it will be asked, how can peculiarities of
colouring serve as marks of the species, when these
generally act at a distance ? How, for instance, can we
explain the eyes in the peacock’s tail ? The explanation
given above seems to fail here ; and as we have
rejected that form of sexual selection according to
which “the finest eyes” charm the females most, we
must find a better explanation.

We have seen that it is very important for all
animals to have specific characters, so that the sexes
may easily find each other, and be not liable to make
the fatal error of confusing their fellows with their
foes. It is clear that the specific colours of many
species have arisen in this way as means of recognition.
But it is also clear that visible characters do not suffice
in the case of the birds. The light creature soars high
up into the air, and is not tied to the ground like the
mammal. With its keen eyes it looks down on a
broad expanse of territory. But how can the finest
eyes pierce through the canopy of leaves to find its
fellows sitting beneath ? And how can the nocturnal
birds, such as the owls, find each other so well ? Even
|:if their eyes can pierce the darkness, they must fail

96 DARWINISM AND THE PROBLEMS OF LIFE

to detect their fellows in the wide forest. The mammal
has an easier task. He follows the track of his
companion with his nose ; but the air leaves no
tracks.

In all these cases sight is of no use in detecting the
species ; it has to be aided by another sense — hearing.
The voice is developed as a means of recognising
the species. But it not only serves the purpose of
bringing the sexes together ; it is of the greatest
importance in the common life of the bird. We know
how powerful the social instinct is in birds, and we
have learned to appreciate the value of this gregarious
sense for the maintenance of the species. Apart from
the fact that the young learn continually from the
older, they are also protected by them from danger.
Every sportsman knows that when he is approaching
a flock of rooks, and one member of the flock sees him,
it is useless to go any farther. The understanding
between the flock can only be brought about by voice.

In the social life of many animals it is extremely
important to specialise the call, as it is an immense
advantage to the species if the bird can produce different
notes. In that case one note will serve to bring the
flock together, another to warn them of approaching
danger, a third may be the signal for flight. We are,
in fact, astonished at the diverse cries of the crows, and
the different notes of the blackbird, which is often a
herald of warning even to other animals in the forest.
Nearly all migratory birds have a peculiar call on their
long, nocturnal travels, in which some means of keeping
together is necessary. But it is especially the pairing-

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97

call, for bringing- the male and female together, that is
peculiarly developed in most birds.

From the pairing-cries, which were at first common
to the two sexes, there were gradually evolved sounds
that differed for each sex. This was effected by sexual
selection, which favoured those males that could make
themselves known at once as suitors to the heated
females. Quite a number of birds are still at the stage
of “ sexually different notes.” The grey wood-pecker
gives out his clear-ringing cry from the highest branch of
an oak, and is answered from afar by the different note
of his mate. Even the cuckoo is said to have different
notes in each sex. When it gives out, in ardent passion,
its trisyllabic cry “ Cuck-cuck-cuck,” we usually hear
shortly afterwards the continuous note of the female. It
is a sign that the love-message of the male has been
heard.

Here we have reached the basis of song — the special
call of the male — and it will be asked how the further
development, up to the noble song of the nightingale,
came about. Again, however, we must depart from the
theories, as we have rejected “female choice.” More-
over, the song is not mainly intended for the female,
since the male usually sings alone, and often, like the
blackbird, on the top of a tree, and so is easily seen; while
ithere is no female near to see him. But the song would
!be just as unintelligible as a means of intimidation ; at
rthe most, we may assume that it has become so much
: developed and specialised because it is useful to the
< male to let his presence be known far around, so that
( any unpaired companion may know from afar that the

gg DARWINISM AND THE PROBLEMS OF LIFE

lady of the district has a spouse. Nevertheless, this
suggestion must not prevent us from confessing candidly
that we have as yet no satisfactory explanation of the
complicated song of the bird.

And how the songs of the birds differ ! The
monotonous “ delm, dilm, delm, dilm ” of the willow-
wren, the rolling flute-like song of the hedge-sparrow,
the strong exulting note of the chaffinch, the rippling
song of the black-cap with its bell-like ending, the
melancholic, varied tones of the song-thrush, and the
indescribable song of the nightingale ; what variety in
the fulness of tone, in the change of the notes, in the
rhythm !

Birds not only sing, but many of them play a very
peculiar instrumental music. Storks clap with their beaks,
bitterns pump their gullet full of air and give out the
powerful bellow that has frightened many a traveller.
The spotted wood-pecker and its black companion fasten
themselves on the branch of a tree, and with rapid
stroke of the beak, helped by the vibration of the branch,
send a humming rattle through the wood. Those who
go through damp meadows in the spring hear a
mysterious tone like that of a hautboy vibrating through
the twilight. This is caused by the snipes, whose tail-
feathers are set in vibration by the air like the tongues
of a reed-instrument, as the bird is descending, and with
a peculiar quiver in its wings sends a current of air
through them.

Some birds are able to imitate the sounds of others.
The jay is a great artist at this work. This pretty
but thievish bird, with its fine blue epaulettes, often

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99

delights in imitating, in the most disconcerting way, all
kinds of bird-voices, as well as the neigh of a foal, the
bark of a dog, and the swish of the scythe. Its com-
panion in robbery, the wood-chat, strings together the
most varied notes, such as the croaking of frogs and
a number of other sounds, with the bird-songs it hears,
into a charming song. Imitation plays a great part
in all songs ; in fact, Wallace believes that the song of
the bird is entirely due to imitation. That is not
correct, however. The bird has an instinct to its
particular song, otherwise there would be no specific
songs at all. But this instinct, as in the play of animals,
may not be developed with full precision, and so the
accession of a second instinct, that of imitation, enables
the creature to improve its voice by hearing and practice.

What pleasure the bird takes in its song ! Anyone
who has watched the singer will know this. It is
certainly not love alone that inspires its song, as the
bird sings long after the love-period is over. During
the hatching, we still hear the note of the chaffinch, and
the song of the yellow-hammer and the black-cap. In
the autumn the voice of the blackbird trills out once
more ; also the song of the willow wren, and the tender
ripple, like the splash of a tiny waterfall, of the red-
breast. When the ground is covered with snow in the
wood, when the fir-branches bend under their load of
snow, and everything sparkles in the sun, we often hear
the song of our smallest bird, the wren ; and the water-
ousel sings its spirited, rippling song by the brook in the
severest cold of January, and then, to the astonishment
of the observer, dips into the icy flood.

TOO DARWINISM AND THE PROBLEMS OF LIFE

Otherwise, all is quiet in Nature in the winter. A
few grain-eaters, like the titmouse, pick up a precarious
living. There is only one bird, the cross-bill, that has
its time of plenty in the winter, as the pine cones are
then ripe ; and we see the wonderful sight of the red
and restless gipsy-bird building its nest and rearing its
young on the snow-covered pines. But all the birds
that live on insects, and amongst these are our best
singers, have migrated far away in the autumn, where
a fresh summer smiles on them under a sky of perennial
blue.

This enormous journey across the Mediterranean to
Africa only takes them an astonishingly brief time to
perform, as the little birds can attain a very high speed.

Henry II. of France found out in the sixteenth
century how fast a bird can fly. A falcon escaped from
him at Fontainebleau, and was caught twenty-four hours
afterwards in Malta. When we calculate the distance
between the two places, we get a speed of forty-four
miles an hour ; but this is below the mark, as the falcon
would hardly do it in one flight and in a straight line.

The expert whom we mentioned at the beginning of
the chapter, Gatke, puts the speed of migratory birds

for instance, that the northern
blue-throated warbler does its journey from Africa to
Heligoland in one spring night, because at the time of
its migration it has been seen in swarms in Heligoland
while only a few stragglers were found in the rest of
Europe, and the bird always travels by night. If this
were so, its speed would be 209 miles an hour. It is
true that the route and the migration of the blue-throat

far higher. He maintains,

BIRDS

IOI

are still obscure, but Gatke’s calculation must be too
hio-h, and we will turn to safer figures. We know from
exact observation that wild ducks can fly more than
forty-seven miles an hour, and carrier-pigeons seventy-
two miles an hour. The highest known speed was
reached, according to a careful experiment, by a house-
swallow, which travelled from Ghent to Antwerp in
1 2 *5 minutes, and so must have done 186 miles an hour.

The bird can, of course, increase or lessen the speed
of its flight, according to need. Hence these figures
cannot tell us anything certain with regard to the
speed of migration. We know little, moreover, as to
the duration of the migration. It seems that many birds
make a halt at suitable spots, but others continue their
flight without interruption to the end, while the weather
permits.

It is marvellous how a bird can maintain such a
velocity so long, yet we never see any signs of fatigue
in migratory birds. It is only a violent storm that
distresses them, and if they are surprised by one at sea
thousands of them may perish in the waves. Many
species of land-birds can alight in a calm sea without
being drowned. Gatke has seen the snow-bunting, the
mountain-finch, and the thrush do this.

Most ornithologists believe that it is the altitude at
which the migration flight takes place that enables birds
to make such long stretches ; they say that the birds
meet less resistance in the upper air. We are also often
reminded of the special adaptation of the bird for flying
■ — the air-sacs that are found in its body and the bones
filled with air, which increase the volume of the animal

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DARWINISM AND THE PROBLEMS OF LIFE

and so lessen its specific gravity. The latter point is
undoubtedly correct, and it is also true that a thin
atmosphere offers less resistance to flight than a denser
one. However, the chief use of the air-sacs, which
extend in the form of hollow outgrowths of the lungs
into the body-cavity and the bones, and between the
muscles, is now thought to be that they spare the bird
the trouble of respiratory movements during flight. In
particular, the reservoirs of air between the flying-muscles
are pressed together like bellows by the movement of
the wings, and thus to some extent automatically renew
the air in the lungs.

Besides this adaptation for flying there are many
others. The bird is, as we say, a mass of adaptations.
There is on its breast-bone a strong comb to which
the flying - muscles are attached ; the whole of the
shoulder-blade is most beautifully constructed ; and the
rigid pelvis, formed by the fusion of a number of
vertebrae, enables it to keep upright while sitting.
In harmony with the laws of leverage all the heavy
parts are placed in the centre of the frame ; the crop
supplies the place of teeth ; the muscles of the leg are
developed well up in the body, so that the limbs
themselves are thin and light ; and a particularly good
digestion enables it to disburden itself at one effort.
In a word, we could show the adaptiveness of every
single organ, to say nothing of the feathers. Every
stroke of the wings lifts the bird up ; and as the
wings are lifted the air rushes between the feathers,
so that they meet no resistance. A wind coming
from the front fills the wings, and enables the creature

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103

to rise rapidly without any exertion ; and they can
also easily fly with the wind.

We see, therefore, that the bird is enormously
assisted in flying by the nature of its organism. We
may now inquire whether the statements made with
regard to the altitude it reaches are supported by
observation.

When we follow the flight of birds of prey they
seem to rise to immeasurable heights, and even the
lark often passes beyond our vision into the blue
sky. But it would be premature to draw any inferences
from this, as we do not know how far we may not
be subject to illusion by dazzling. The results of
balloon observations are more important. In these
an eagle was once seen at a height of 3,300 yards and
a lark at a height of 1,500 yards; but there were so
few birds at this height that we must conclude they
rarely rise above 1,100 yards. It was also noticed
that a pigeon, which was dropped from a balloon at
a great height, first fell downwards, and only found
sufficient resistance for its wings to use properly in
thicker strata of the atmosphere.

However, these facts gives us no information as
to the altitude of the migration-flight, and unfortunately
we have not very many observations on this. Gatke
was one of the few who have seen swarms of migratory
birds go past, and he gives a superb description of
one night in October in which this wonderful picture
unrolled before him. It was a dark, starless night,
only lit by the rays of the light-house which seemed
to reach out endlessly into the night. The darkness,

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DARWINISM AND THE PROBLEMS OF LIFE

the perfect silence of Nature, and the consciousness
of the nearness of the vast sea, awoke a feeling of
sublimity in the soul of the observer. Then the cry
of a bird broke the stillness, then a second, and the
noise grew louder and louder, until at last countless
flocks of birds of all kinds shone like sparks in the
beams of the light - house, circling round it like a
snow-storm, and then disappearing in the impenetrable
darkness. Larks, starlings, plovers, snipes, and many
other species were recognised by him. At one time
an owl appeared, and then passed with loud flap of
wings into the darkness, accompanied by the plaintive
cry of a thrush that had been caught in the general
turmoil.

When the moon and the stars shone, the sight was
less splendid, as the birds then flew higher, and were
not caught in the light of the lantern. It seems, then,
from Gatke’s observations, that the migration does
not take place at a great height, at least on cloudy
nights ; and this has been confirmed by recent
observations . 1

Aeronauts have let loose various birds from balloons,
and it was found that in clear weather the birds went
straight downwards. But if the balloon was above
a thick stratum of cloud, the birds were puzzled and
flew hither and thither, and settled on the balloon
again ; though they immediately left it when it fell
below the clouds and the earth could be seen. They
then made for the ground. The same thing happened
if there was a break in the clouds through which the
1 Gatke himself held to the theory that the birds fly high.

BIRDS

105

earth could be seen from above. In that case the
birds at once took their direction, passed through the
opening, and flew downwards.

If we compare these observations with Gatke’s it
seems pretty certain that the birds do not need to rise
high during the migration-flight. It is true that the
question at what height they fly in clear weather is still
far from settled, but we may say that, if they fly at
a lower level in bad weather, yet probably reach their
end just as quickly, a high level does not seem to be
necessary for speed. Hence the rapidity of the
migration-flight is not explained by the theory of the
thinness of the air.

A second question now arises. When they are at a
low level the birds can only see a small part of their
route, and none at all during the night ; how is it, then,
that they choose the right way at such enormous
distances ? We will approach this question in the
method we have used several times already, and inquire
how the migratory instinct may have been developed
in the course of time.

The actual migratory birds formerly lived, we assume,
in southern latitudes, and gradually increased until they
over-populated them, and food became scarce. The
famine was worse in the dry season, when vegetation
shrivels up in Africa, and the insects especially, which
form the chief food of the actual migratory birds, were
reduced in numbers. The hungry birds were thus
compelled to abandon their habitation, and travel in
every direction, seeking food and nesting-places in less
crowded regions. A number of them came northward ;

io6

DARWINISM AND THE PROBLEMS OF LIFE

and as fresh arrivals from the south came in later years
of famine, the place was again too small, and they had
to spread in all directions, including the north.

Could the spread towards the north proceed
indefinitely? No; because the time came when the
wanderers had passed the winter-limit. When the cold
season broke on them, the earth became covered with
snow, the streams froze, and famine set in again.
What happened to the poor birds ? Those that
remained, waiting for better days, were destroyed, as
the lack of food lasted longer than they could endure ;
others, that fled to the north, east, or west, found the
same conditions everywhere and perished also ; only
those were saved that remembered their origin and the
land of eternal summer, and returned southwards.

We may confidently assume that these little creatures,
barely escaping from death, would not at once return to
the north. But natural selection — for it is with this
we have to deal — is inexorable. The birds were back
in fully populated lands, and when the nesting -time
came in spring there was no room for them ; we know
that most birds require a certain area for nesting, and
will suffer no others of the same species within that
area. The wood-pecker, for instance, and a great
number of others, including our gentle robin, act in this
way. What happened to these birds that had become
strangers in their old home ? Many of them failed to
breed ; these were the most timorous who would not
return to the north, and died out through leaving no
offspring. But there would certainly be bolder ones
here and there, who would remember how they had

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107

nested undisturbed in the previous summer, and fly to
the north once more.

This was repeated time after time. In a long period
of time and certainly not without enormous numbers of
victims, Nature fashioned a provident and hardy race of
birds ; provident because they would fly south as soon
as the cold set in, courageous because they ventured
back to their old nesting-places in the spring. Natural
selection further regulated the time of flight. The birds
were not to start too early from the south, or they would
find their old nesting-place still buried in snow : and not
too late, or they would not have time to rear their young
so as to be able to make the great migration. The young
would accompany the older birds when they gathered
for departure, and would observe the route so as to be
able to teach it to their own young afterwards. And as
those that would not make the flight at the proper time
were always destroyed, there arose the species of
migratory birds which still carry out their flight with
such wonderful exactness . 1

German ornithologist, Kurt Graeser, has recently given a different
theory of migration. He believes that the migratory birds are the
original type, and the non-migratory have descended from them.
According to him, the first birds lived on a very different land from
what we have now. It had enormous stretches of water, ice-fields,
steppes, and forests, which could give no food or shelter to the birds,
and had to be rapidly covered in order to reach places with plenty of
food. The primitive birds, therefore, must have had the instinct of
wandering restlessly and swiftly over the whole earth. Gradually the
birds would see that certain places were especially favourable for them.
They flew to these more and more, and from this habit was formed the
habit of definite migration. Later some of the birds found it better to
remain in one place, and were adapted by Nature as required. The
author believes that in time all birds would cease to be migratory, and
adapt themselves to a different diet and the privation it would entail.

IO&

DARWINISM AND THE PROBLEMS OF LIFE

At first the route was comparatively easy to find ;
but the further north they spread the more intricate it
would become, the more strength it would require to
traverse it, and the earlier the start would have to be
made. But as they only spread gradually, this advance
would be quite possible, as only the strongest would be
able to meet the demands of the longer flight, and
amongst their progeny, which would go still further
north, again only the strongest would survive ; so that
the power of covering long distances in the shortest

To this theory we may object, in the first place, that there is no
proof whatever of the earlier condition of the earth compelling the
birds to cover wide stretches. In fact, it is not at all clear that steppes
and forests would afford no food and shelter to them. It is just the
opposite. It is not sufficiently borne in mind by the author that the
migratory birds live on insects, and that the migration is precisely
regulated by the alternate abundance of insects in the north and
south, and that the use of this rich provision of sustenance is an
admirable adaption. It would be a curious retrogression for the
migratory birds to adapt themselves to food that is already so much
sought by other animals. And to adapt themselves to privation !
Further, the basis of selection, the over-production of progeny, is lost
sight of, yet this is the principal ground of the migration. In the
author’s opinion instincts are inherited habits. We shall refute this
theory in the sixth chapter ; but even if we admitted it, what was the
origin of the habit of the primitive birds to fly over the earth ? Among
the unconvincing objections that the author raises against other
theories of flight we find the following : “ The birds could not know
that there was food for them in the south.” But this difficulty only
exists in the author’s own theory, and for this it is formidable. How
could the primitive birds know that they would find plenty of food if
they made long and rapid flight over desert wastes ? Finally, the whole
theory is impossible because a simple reflection tells us that the first
birds cannot have been migratory. The birds must have evolved from
creeping animals ; their ancestors were reptiles, something like the
present lizards. It must have taken an enormous period of time for
their flying organs to have become powerful wings; only after vast
numbers of generations would they be sufficiently advanced to attempt
long flights without resting.

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109

possible time, which excites our admiration to-day, was
gradually developed. The faster the birds travelled,
the more time they had for breeding, the more young
they could bring into the world, and the more quietly
they could rear them. Hence the speed of the flight
was constantly increased by natural selection.

Gatke raises the difficulty that every blue-throat that
must perform this rapid flight lives on the ground, and
never really makes use of its wings except during
the migration. Just as a man’s arm becomes weaker if
it is not used, so it must be with the blue-throat, and we

cannot see how it will be able to make the enormous
distance.

It is true that disuse enfeebles an organ, but as only
those blue-throats survived that flew quickly in the
migration, their strength was increased so much by
natural selection that disuse could not lessen it much —
at least, not enough to incapacitate them from flight. One
thing is clear. If the impairing of the flying-power by
disuse was inherited \ the blue-throats would certainly
become weaker and weaker. But this is not the case,
and so it is clear that Gatke does not impugn natural
selection, as he supposes, but the Lamarckian
principle, by his difficulty. We will bear in mind
this first case in which the principle conflicts with
reality.

The second effect of natural selection was to increase
more and more the bird’s power of presentiment. The
wanderers must not wait for the snow and ice to tell
them that the winter has come, but must take their flight
before these appear. Thus the marmot foresees the

I IO

DARWINISM AND THE PROBLEMS OF LIFE

winter scarcity of food, and stores up grain in its den in
the autumn.

Thirdly, the bird’s sense of direction had to be
improved. Otherwise how could they find their way on
the long journey ?

There is, however, another theory. Remember how
we conceived the origin of the migration. Among the
birds that penetrated further north only those survived
that flew south at the beginning of winter. May not in
some of the birds an instinct have arisen in the course
of thousands of years, during which natural selection
was at work amongst them, to fly straight to the south
when the cold weather set in ? These birds would thus
be preserved, and might transmit this instinct — which
does not differ essentially from the instinct that forces
the salmon up the river — in increasing power to their
offspring, And may not an instinct have arisen by
selection to keep the route unerringly during the migra-
tion so that the animals will reach the warm countries
in safety? Certainly the formation of a “magnetic
sense ” of this kind by natural selection is quite possible,
and the Siberian traveller, Middendorf, believes it is
present in migratory birds . 1 Such an instinct is not
more wonderful in principle than the marmot’s instinct
to store up grain, or the bees’ instinct to build their
ingenious cells.

But we know from observed facts that the migratory
birds do not regulate their flight by a magnetic sense.
They do not fly straight, but follow certain paths which

1 There are many animals with senses that cannot be reduced to
any of our familiar five senses.

BIRDS

[ I I

often change in regard to the four quarters. A mag-
netic sense would be expected to guide its possessor
in the straightest possible line.

The migration - lines of the birds show, on the
contrary, that the travellers know the way to their old
home , and that they travel along the same paths as
their ancestors did. It is clear that the animals, in
their extension northward, only sought localities that
promised them sufficient maintenance. A sea-bird,
though its nesting-places are spread far and wide over
the shore, will not fly over the land, but along the sea,
where alone its food is to be had. Now we find that
the migration-paths of the sea-birds always run along the
shore and never cross any extensive land, although their
goal, the winter quarters, could be reached much more
quickly by land. These circuitous routes are very
striking in many species. The Richard’s pipit, for
instance, nests in East Siberia, and migrates from
Heligoland to West Africa, instead of straight to
China. 1 How can we understand such an aimless
direction, unless we admit that the paths of birds follow
the ancient line of advance, the recollection of which
has been transmitted from generation to generation ?
The animals spread gradually further and further north,
and each time some of the descendants nested in a
higher latitude than their ancestors. Hence the further
north a species of migratory birds nests to-day, the more
nesting-places of their progenitors must they fly over
during the migration. And as these nesting - places

Some of these birds, however, must fly to China and Ceylon. We
must suppose that this variety has spread from the south of Asia.

I 12

DARWINISM AND THE PROBLEMS OF LIFE

could only be where there was means of sustenance,
the line of migration must pass over these localities,
and so follow the ancient line of expansion.

This is seen in the paths of all migratory birds.
River-birds travel along the rivers, though also over
high mountains, as here also there are streams and
lakes that afford them sustenance ; while marsh - birds
go round the marshless hills. Land-birds go straight
ahead over the country, and only halt at the sea, and
diverge along its shore. The fact that European birds
still cross water, namely, the Mediterranean, is ex-
plained by the circumstance that there was not always
water where the waves roll to-day. In the earlier
periods of geology there were bridges of land from
Africa to Europe, through Malta and Sicily as well as
at Gibraltar. Over these the birds could advance
gradually towards the north, and as a fact we find that
the sea is only crossed by them at these points.

Let us now picture the migration to ourselves once
more. A pair of birds travel to the north, rear their
young there, and return with these in the autumn to
the old home. In the spring they all return to the
nesting-place of the previous year, but some of the
young go still further north to build their nest. The
journey in autumn will consist of two parts for these.
They have already done the larger section of it twice
with their parents ; the second is the stretch from the
nest in which they themselves were reared to the new
home that they have made. But both sections of the
journey are only the first part of the journey for their
offspring, as these will add to it by advancing further

BIRDS

II 3

north. In this way, from the fact of each succeeding
generation adding a piece, however small, to the original
journey, we get in the course of an enormous period the
gigantic travels of our actual migratory birds. And
as the route is only a little longer in each generation,
selection does not make too exacting a demand on the
birds, and there will always be some that can perform
the longer journey.

Thus the power of flight has been strengthened
gradually, and the sense of direction has steadily
increased up to its present pitch. This sense consists
especially in a marvellous memory, which has grown
steadily as the route lengthened. If we did not know
that it had been built up gradually, we should hardly be
able to understand to-day how the birds can retain an
impression of the routes they have only travelled over
twice with their parents. But this memory is not so
much a capacity for observing the path over the regions
they have traversed as the power to keep the various
directions that they took in their flight, and so there
must also be a sense of orientation, or direction, that
enables the birds to keep their way even when they are
turned aside. That they do not need to any great
extent to look down on the country is clear from the
fact that night-time is often chosen for the migration.
Nevertheless, they do need some sight of the earth,
however faint and shadowy, otherwise they would rise
above the clouds, and would not fly so low in bad
weather.

However, this enormous development of memory in
the migratory birds is not altogether strange. Even

I 14 DARWINISM AND THE PROBLEMS OF LIFE

amongst men there are memory-prodigies. Who has
not heard of the Hindoo who could repeat, word for
word, long stories that he had only heard once. If
circumstances arose that brought about the survival of
such men alone, there would soon be a race on the
earth with prodigious memories.

Nor is there anything mysterious about the sense of
orientation that enables the bird to keep the right
direction when its eye cannot see any point to guide it.
There are men that can find their way in the forest
without any path or track. We read that the Indians
never went astray in it. We are, moreover, assured by
some writers that dogs which have been taken away for
hours together in closed carriages or trains will find
their way home by the shortest, and a quite unknown
route, when they are set free. Here we have something
exactly similar to the migration of the bird, which,
though it has been taken a long journey in the darkness
of night by its parents, has retained the direction so
well that it can follow the same route without guidance
in the following year, and never go astray.

Finally, we must observe that the migratory birds are
greatly assisted in keeping to the right way by the fact
that their social instinct is developed especially strongly
at the period of migration, and vast flocks of them make
the journey together. Whether some older bird that
knows the route from having migrated several times
leads the way, has again been called into question of
late. This is not necessary, however, as we have seen.
In any case, it is an advantage to travel in flocks,
because a large number of birds will be less likely to

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115

go astray than a few ; and the considerable power of
communicating which the bird has will certainly help
them to reach their goal more safely.

It was, therefore, an iron necessity that implanted
lithe instinct of migration in the bird’s breast. Their
wonderfully developed faculty must have been pur-
chased at the price of innumerable victims.

It was necessity also, that compelled our ancestors
to migrate. They were forced to leave the primitive
home that had grown too small for them, and was
^overwhelmed with other peoples. They were driven
j iinto lands where the hot sun melted down their
morthern vigour like snow, and where the dark waves
■of southern races passed over their blond and handsome
features. So perished heroic races. But others
iremained, and retain the spirit of the old vikings in
the life of Europe to-day.

CHAPTER IV

REPTILES AND AMPHIBIANS

Principle of animal classification. The general properties of animals
explained by heredity and adaptation. Darwinian justification
of classification. Reptiles and amphibia of former ages. Earlier
periods of the earth. How and why the earth has changed up to
the present. How the remains of earlier animals have been
preserved. Gaps in the remains of extinct animals. Primitive
man. Conflicts of extinct animals. Why the gigantic forms of
earlier ages became extinct. The death of species. Trans-
formation of species. Why ancient species have been
preserved. Why there are still animals of the simplest type.
Predominance of a species of animal. Predominance of
man. Any variation is possible. Origin of flying animals.
Life of our reptiles. Prey. The creeping of serpents. Re-
generation, the power to re-form lost members. Its origin by
natural selection. Frog-spawn. The skin of amphibia. Repellent
and warning colours on nauseous and poisonous animals.

The man who devotes himself to the study of living
organisms is overpowered by the inconceivable variety
of their forms. He would have to despair of ever

obtaining a grasp of the world of living things if he
had not in language a means of ranging a vast number
of forms under one convenient name. With one word
he can designate countless numbers of animals, each of
which is different from the other, by ignoring the
differences between them and fastening on what is
common to all the individuals. The word “ fox ”

enables us to grasp a countless number of animals, by

representing to us the common element of them all.

1 16

REPTILES AND AMPHIBIANS

II 7

Science pursues the same method. It seeks the
common element in wider and wider groups of animals,
and overlooks what is individual. Fox, wolf, weasel,
marten, are regarded in their common features, and
described as “carnivores” or carnassia. All “species”
are distributed in “orders” of this kind. The work
is carried even further. Some of the orders of animals
are found to have features in common, and these are
bracketed together as “classes.” Finally, the “classes ”
are distributed into “ stems.” Thus the vertebrate
“ stem ” represents what is common to the five
“classes,” mammals, birds, reptiles, amphibians, and
fishes, namely, the possession, first of all, of an internal
axial skeleton. This feature is not found in the other
stems, the members of which are at the most covered
externally with hard parts.

It is the merit of Darwinism to have established that
there are in the nature which we really know no
“species,” but merely a countless number of individuals,
each of which is unlike the other. Darwin has shown,
in fact, that the feature which is common to certain
forms, and enables us to grasp them as a “ species,” is
not always absolutely fixed. When, for instance, we
find that a number of individuals agree in having “ long
ears and so can be formed into a species, differing
from another or short-eared species, we see also that
there are other animals with ears of intermediate length.
Such animals could with equal right be put in either of
the two species.

Lut while Darwin has destroyed species as realities ,
he has at the same time fully established the idea of the

I 1 8 DARWINISM AND THE PROBLEMS OF LIFE

species. Formerly the common element that made it
possible to distribute organisms into species, orders,
etc., was taken for granted without discrimination.
Darwin, and a few students before his time, have tried
to show why there are common features amongst living
things.

There are two laws that explain these common
elements in the animal world. One is the law of
adaptation; and we shall see later that adaptation to
precisely the same conditions can bring such very
different animals as worms and spiders to resemble each
other. The second is the law of heredity. According
to this law organisms have more in common, the closer
their blood-relationship is. Any person can verify this
from human life. However, it is not as simple as it
seems at first sight, and we shall see, when we deal with
the phenomena of heredity, that frequently men who are
only distantly related resemble each other more than
brothers and sisters.

The law of heredity gives a general validity to the
classification of the animal kingdom, as it was set up
formerly on the ground of common features ; we have
much the same arrangement when we classify them
according to generic relationship. There are, however,
many exceptions, and these are explained by the first
law. Animals were formerly classed together which
resembled each other externally through some similar
adaptation. But the more thoroughly they were

investigated, the more they were found to have in
common with different animals, and they are now
distributed in other orders and classes. This common

REPTILES AND AMPHIBIANS I 19

element, which is due to the law of heredity, affects
animals far more profoundly than the common features
due to similar adaptations, which are generally external.

In our time it is sought to base classification
exclusively on the law of heredity, all animals being
regarded as a gigantic family and classified according to
their degree of kindred. Thus the classification of
animals has been intrinsically justified by Darwin.
The common element on which it is now built is
scientifically explained by the law of heredity.

«••••••

In the present chapter we have to deal with two
classes, the reptiles and the amphibians, and we can
do this the more easily as both classes have few
representatives in Europe. Reptiles and amphibians
require heat. The temperature of their blood rises
with a higher external temperature, and gives more
vigour to their vitality. Hence it is that we meet
more species of the two classes the further south we go,
and more highly coloured and powerful animals in
proportion to the length of summer in the district. The
giants of the reptile class and the largest amphibians
live in the moist tropical forests, where the rays of the
sun are almost unendurable to us. The serpents wind
through the bush like living branches of trees, the
crocodile lurks in the broad river for the animals that
come to drink, and the voices of the tropical frogs
resound at night like the roar of oxen.

At one time it was different here.

Many millions of years ago, in what are called the
Jurassic and Cretaceous periods, there were large

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DARWINISM AND THE PROBLEMS OF LIFE

numbers of huge reptiles in our own latitude. Where
the wind now sweeps in long waves over the fruitful
corn-fields, it then lashed the waves of a vast sea. In
this ancient sea the plesiosaurus, a gigantic reptile with
legs shaped into huge fins, swam hither and thither.
A head armed with sharp teeth crowned a neck eight
yards long. It towered far above the water, and when
unsuspecting fishes came along, the head shot down
with terrific force, to emerge again with the captured
prey.

The ichthyosauria were no less deadly to the fishes
and still more to the cuttle-fishes, or huge polyp-shaped
molluscs. Something like dolphins in shape and size,
these reptiles disported themselves in great swarms in
the sea. There were also reptiles on the land. The
colossal dinosauri broke with heavy step through the
thickets, one of them, the cetiosaurus (of which the
brontosaurus was an American cousin), having a
ridiculously small head. Another huge animal was the
iguanodon. Like the modern kangaroo, the monster
stood on its great hind-legs and heavy tail, and tore off
masses of leaves with its small fore-limbs to thrust in
its horse-like mouth. In spite of their huge size the
dinosauri were harmless vegetarians. They had deadly
enemies in the megalosauri, gigantic carnivores with
teeth as sharp as knives.

Even the third element, the air, had its reptiles at
that time. The pterosauri flew from tree to tree,
spreading out the flying membrane that stretched from
their enormously long fifth finger to the legs, and even
to the tail. The best known of these flying lizards is

REPTILES AND AMPHIBIANS

I 2 I

the pterodactyl. It was not itself very large, but it had
relatives with wings that measured eight yards.

We have to go further back in the history of the
earth for the period when the amphibians flourished
most. The largest forms of this class lived in the
Permian and Triassic periods. These were the
stegocephala, huge beasts that lay in ambush for their
victims in the prickly thickets. The yard-long jaws of
the mastodonsauri were armed with numbers of sharp
teeth ; their belly and skull were protected by powerful
armour, and they had, besides the two eyes, a third or
cyclopean eye in the middle of the forehead.

The fact that the amphibians were before the reptiles
in the history of the earth is a proof that the latter
descended from the former. Geology shows that the
succession of the five classes of vertebrates was the
same in the history of the animal world as it is in our
classification. The earliest geological finds known to
us are remains of fishes alone, and these increase in
variety. The first amphibians appear in the Car-
boniferous period, and they are followed in later epochs
by the reptiles. In the Jurassic strata we find the first
bird, the archeopteryx, of which we spoke above; and
the mammals do not reach the height of their
development until the Tertiary period.

But, it will be said, fishes are highly organised animals,
and according to our theory there can only have been
extremely simple organisms in the beginning. How
is it, then, that we find fishes in the oldest strata ? 1

1 To be quite accurate, in the second oldest, the Silurian. But as
these fishes have an advanced organisation, it is clear that there must
have been fishes in the oldest period known to us, the Cambrian.

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For the simple reason that, though these strata are
the oldest known to us , they really represent terrestrial
epochs that had many predecessors ; but we have no
documents relating to these periods. The book of the
history of organisms only opens for us when there is
already an immense wealth of forms on the earth.
Besides fishes, there are crabs, mussels, and other
animals, the development of which from the lowest
organisms must have taken enormous periods of time.
At first there must have been merely particles of
living substance, and in comparison with the countless
series of modifications that lead from one of these to the
fish, the very much shorter series between the fish and
the mammal is insignificant. We may say, therefore,
that the pages of the archives of the earth’s history that
have been preserved only relate to the “ modern period”
of organic life, and that “ antiquity” and the “ Middle
Ages” are lost to us, and will never be recovered.

The earlier of the ecological strata lie below the
later ; the most recent lie at the top of all. As
geologists penetrated deeper and deeper in their
examination of the strata, and still found animal
remains in the earliest deposits, there suddenly appeared,
below the earliest fossiliferous layer, one that had no
organic remains whatever. Experts still differ about
these empty masses of rock. Many regard them as
the crust that was formed when the surface of our
planet, at that time a mass of molten liquid, cooled
down. At this period of incandescence there cannot
have been any living things, and we ask for the strata
that lie between this crust and the deposit that contains

l

REPTILES AND AMPHIBIANS

I23

the earliest animal remains. Here we find a yawning
gap. No one can say what has become of the missing-
strata. Many think that they are at the bottom of the
sea ; others see them in the upper layers of the non-
fossiliferous rocks, which have destroyed all the remains
of animals in the incalculable lapse of time, and owing
to pressure and decomposition. However that may be,
we must take into account the fact that the whole period
from the first appearance of life on the earth up to
the development of these highly organised animals is
hidden from us.

Moreover, our discoveries in the periods known to
us are very defective.

In the fossil remains or impressions of former animals
we have, as a rule, only the hard parts of organisms.
Hence animals that had no hard parts could leave no
trace of their existence. There is also another
circumstance that tells us the remains we have represent
only a small portion of the animals that lived at that
time. The strata that contain the fossils are formed
exclusively in water. The rivers carry stones with
them from the mountains, grind them up into fine mud,
and convey this to the sea, where it sinks to the bottom
and covers up any remains of animals that lie there.
These deposits of mud are gradually converted into solid
rock containing the animal remains ; and when the sea
recedes, the rock becomes the basis of new land, and
may be elevated into a mountain by the creasing of the
earths surface. If one of these strata is left dry for a
long period, and then covered by the sea once more, a
new stratum is formed on top of it. But there will be

124 DARWINISM AND THE PROBLEMS OF LIFE

a wide gap between the new organisms and those
buried in the older stratum, representing the time
during which the earlier stratum was dry land. Thus
we can understand the gaps in the passage from one
species of fossils to another. Further, we can see from
the nature of this sole means of preserving animal
remains that land-animals can leave us no trace of their
existence, or at all events only if they are carried into
the water by accident and deposited quietly at the
bottom of it.

But there will be a still further reduction in the
number of animal remains preserved. All the seas of
former days were not fed by rivers that brought mud
to them, and in those without slimy bottoms animal
remains would decay. Moreover, remains might not
be preserved that fell into the water at places where
the rivers brought down coarse debris into the sea,
which would grind everything up.

Further, when the fossiliferous strata were raised out
of the sea their contents were exposed to fresh dangers.
An enormous amount was destroyed by weathering,
rain, floods, and surge, carried away by the rivers and
ground down into mud again, and so had to begin the
cycle afresh. And when the crust of the earth burst,
became creased or folded, and threw up chains of
mountains, many remains were squeezed until they
became unrecognisable.

Besides all this, the sea still holds from us
incalculable treasures, and there are others in lands that
have not yet been opened up. When we further
remember how few of the remains that are found come

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125

nto the hands of experts, we should not be surprised
hat we have not fossil remains of all the transitional
yrpes. We must not expect to find the remains of long
eries of ancestors of any particular species, showing us
ow it was gradually converted into a different one.
Ve must not question the theory of evolution because no
luman skeletons have been preserved in which the
ton-human element predominates.

If, then, such discoveries are made, if the famous
'teinheim snails 1 bring before us the conversion of one
pecies into another in all its stages, and if the
Neanderthal skull and other human remains give us
nformation as to a primitive humanity, we must learn
o appreciate the fortunate accident to which we owe the
reservation. As a matter of fact, however, we shall
laim full credit for the theory of evolution precisely
)ecause the evidence of geology, in spite of its
ncompleteness, affords striking testimony to the truth
bf it.

We regard the remains of those monstrous reptiles
vith astonishment, and ask how it was possible for
uch powerful creatures to become extinct. We find,
owever, that towards the close of the Cretaceous
eriod gigantic sharks appeared, measuring twenty-
ight yards in length, and we can well believe that
hey finished off a good many of the ichthyosauri. But

1 These snails are found in immense numbers in the Steinheim
eposits. One stem-form has divided into four groups of varieties, and
he transitional forms have been admirably preserved. The stem-form
s lowest in the strata, the transitional forms higher up in proportion to
heir divergence from it.

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DARWINISM AND THE PROBLEMS OF LIFE

how could the sharks develop to such a size, as they
only appear at a time when the reptiles had long
dominated the sea, and had been a danger to the
ancestors — probably much smaller — of the sharks ?
We can hardly admit that the sharks would be
developed so much more rapidly than the great marine
lizards. In fact, we saw in the first chapter, in the
instance of the fox and the hare, that two species that
live in a bioccenosis cannot extirpate each other, as
the strengthening of one species involves at the same
time more protection for the other.

An effort has been made to explain by means of
an example how a species that has lived with another
for thousands of years may at last bring about its
destruction. The process is supposed to have taken
place between the machserodus and the glyptodon,
mammals of the American Tertiary period.

The glyptodons were animals about three yards
long, something like the modern armadilloes, which
developed a powerful armour as they increased in
size, and this protected the bearer, like the shell of
a turtle, and was very thick. It afforded excellent
protection against most enemies, but not against the
macha;rodus, a tiger that also grew bigger and bigger,
and stuck its enormously long canine-teeth, with edges
like razors, into the glyptodont, in order to suck its
blood, as its enormous teeth did not allow it to rip
it up. We can easily understand how armour and
teeth were improved by natural selection ; in other
words, how those glyptodons lived longest and re-
produced most whose armour was impenetrable to

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127

most of the tigers, and how, when the weaker
individuals had died out, only those tigers could
survive whose long teeth could bore through the
hard coat of the glyptodons. In this way the
balance would change from side to side for ever,
and it could never come to pass that “even the
stoutest armour would no longer protect the victim,
and the huge glyptodons be gradually extirpated .” 1
Natural selection could only strengthen the armour of
the armadilloes if it was near the limit — that is to say,
if a slight thickening made it impenetrable for a large
number of tigers. If the latter could suddenly over-
come all the glyptodons, they must have lengthened
their teeth to the extent of two generations of
growth ; and that would be a leap upwards in the
evolution of the teeth, not a gradual advance. It is
only on the latter, not on leaps, that we must rely in
the modification of species by variation. We must,
therefore, trace the extinction of the glyptodons to
another cause. One might say, of course, that there
were limits in the nature of the animal that would
not allow the indefinite modification of an organ, and
so after a certain time the armour of the armadillo
could grow no thicker. Must there not be some
provision that trees do not grow up into the sky ?
But we shall see in the eleventh chapter that this
phrase, however imposing it may seem, explains

1 Weismann. It is further said that the tigers got the advantage
of the armadilloes by sticking their teeth into the unprotected neck.
But that can hardly have been the case, as then natural selection
would only have to form and strengthen a plate for the neck, and the
dorsal plate would remain as it was, not being subject to attack.

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DARWINISM AND THE PROBLEMS OF LIFE

nothing, and we will keep clear of all attempts to
explain things in this way.

Once the armadilloes disappeared it would be all
over with the machaerodi as well, since they lived
exclusively on them ; their long teeth prevented them
from tearing up or eating other animals like the other
carnivores. But would it not be possible for the
teeth to be gradually reduced by natural selection ?
No; because the teeth were too long for the slight
reductions that variation might afford to enable the
animals to adopt a different diet, and so avert famine.

These two species, mutually affecting each other in
their modification, could only be destroyed by some
accident or other extirpating one of them. We can
only suppose that, as a rule, it is external events
that come to affect and destroy the relation of two
species. If, for instance, in our old illustration of the
fox and the hare, the mice increased enormously from
some circumstance or other, the foxes, which feed on
mice also, would propagate more freely owing to the
abundance of food. If the mice then died off from
some disease, we should find the numerous foxes
reduced entirely to eating hares, and they would soon
extinguish them altogether.

This illustration shows clearly what must happen
for a species to be entirely rooted out — namely, some
sudden accident. Dangers that arise gradually can
be met by a species, which will be gradually
modified. The danger must always be just great
enough for individual variations of the menaced
animals to escape it ; and in the next generation only

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129

so much greater that new variations may again arise
and preserve some animals from it. But if the
danger arises suddenly, or is suddenly increased, the
whole species affected by it must die out, as no
single variation is considerable enough to evade it.

Thus the disappearance of the mice in our illustra-
tion is a sudden phenomenon that at once causes the
hares to face an excessive number of enemies, which
formerly only took part of their food from the hares.
There was not time for the hares to change sufficiently
to meet the numbers of foxes ; their fertility could
not at one stroke be increased enough to cover the
enormous disappearance. There was no time for the
selection of the fittest. If we assume that something-
of this kind took place in the case of the ichthyosauri,
we can understand their extinction. The most probable
contingency is that the sharks came in great numbers
from another region into the sea where the reptiles
were, probably driven out by geological changes.
They increased at the expense of the ichthyosauri
until the latter were completely extinguished. But
the sharks could not suddenly reduce their fertility
and size, and therefore had to go themselves on
account of the lack of food.

We see, then, that a species can be extirpated by
some event that occurs suddenly, in this case by the
immigration of sharks. Physical changes have a
similar effect. If vast steppes took the place of the
rich vegetation of the Jurassic and Cretaceous periods,
the herbivorous dinosauri would be without food, and
would be destroyed. We do not know anything about

130 DARWINISM AND THE PROBLEMS OF LIFE

their extinction, but must not forget that they might
be converted into smaller types of animals ; if, that
is to say, the change in the vegetation took place
gradually, and the smallest individuals, or those that
required least food, were constantly selected. Another
reason why they could not persist in their old size is
that the very thick skull they had may have been a
very good protection ; but it meant only a very small
brain. But a small brain would be quite insufficient
to keep up the vital energy required in the active
life on the steppes.

The pterosauri seem to have been really extirpated,
not transformed, as we do not find their descendants
in the birds. These flying lizards had naked bodies,
and it is possible that a sudden lowering of the climate
might account for their disappearance. The rapid
setting-in of severe cold would not give them time
to protect themselves by developing feathers, as their
relatives, the birds, had already done. All reptiles are
sensitive to cold in a high degree, as we see very
clearly in the lizard, which only displays its full vitality
in the sun. Hence it is that the giant-reptiles can
only be maintained in warm countries, the tropical
zone alone harbouring the mightier specimens to-day.

Thus a change of climate that alters a country may
either compel a species to change, or, if it sets in with
comparative swiftness, extinguish it altogether. But
there is a third contingency. The species in question
may migrate. In this way the species that lived in
Germany during the glacial period retired to the North
and to the Alps, where they are still to be found.

REPTILES AND AMPHIBIANS

1 3 I

Very few of them adapted themselves to the new
conditions.

Physical conditions are bound to modify a group
of animals when they change themselves, as we saw
in the first chapter. This applies not only to changes
of climate, but to volcanic changes, the drying-up of
seas, the sinking of continents, and the folding of the
earth’s crust to form mountains. It applies also to
modifications caused by human culture. Most of these
factors may come into operation gradually, and modify
rather than destroy species. In fact, even civilisation,
which acts comparatively quickly, can modify species
of animals if the nature of them is such that only slight
variations are required to let them breathe the new
atmosphere. We have an instance in the above-
mentioned case of the blackbird.

But there are also changes that arise quite gradually,
yet extinguish a species. When, for instance, a continent
sinks below the waves, however slowly, the land-
animals living on it will be destroyed. What happens
is, not that those animals are selected which are most
accustomed to the sea, but the animals squeeze into the
ever-decreasing territory, and when the time of the last
subsidence comes it is too short to transform them into
aquatic organisms.

We see, therefore, that animal species are only
destroyed when sudden changes set in that make their
former habits impossible ; in other cases natural
selection is given time to modify them.

The word “ sudden ” must not, of course, be taken
too strictly. When an animal has, in the course of

132 DARWINISM AND THE PROBLEMS OF LIFE

hundreds of thousands of years, been transformed from
an arctic to a tropical organism, from one with a thick
fur to one with a thin coat, it is clear that a fresh
lowering of the temperature will be “ sudden ” even
if it takes several thousand years ; this period would
not suffice to bring back the thickness of the fur which
it took such a long time to abolish. Just as we speak
in geology of “recent” times, although they may be
hundreds of thousands of years away, so in the
geological sense the word “sudden” may involve
enormous periods. It means merely — so rapid that
even favourable variations have not been able to meet
the requirements of the change.

One more question. Can natural selection do every-
thing, if it has time and material enough ? Is it
omnipotent in this respect? Can it transform any
aquatic animal into a terrestrial one, and provide any
land-animal with wings if it becomes necessary ? This
is answered in the negative by most scientists. Many
of them grant some species the capacity of developing
and deny it to others. They say there are four different
types of animals : persistent, elastic, rigid and plastic.
The persistent types retain their form for immense
periods ; there are still in our seas organisms that can
be found in almost the same form in the oldest strata.
Elastic types tend to revert always to the earlier form :
rigid types have only a very slight power of adaptation,
and generally perish when their environment changes :
plastic types continually assume new forms as the
conditions change, and thus conform themselves into
new species.

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133

But it seems very questionable if there really are
these different types of animals. Even the persistent
types have been at one time evolved from lower
organisms, and were therefore once plastic ; their
persistence is not an eternal and unchangeable feature.
That many animals have remained unchanged for very
long periods is clearly due to the fact that this form
was the most suitable for the environment in which
they lived. We must not forget that it is not absolutely
necessary that all the individuals in a species shall be
modified so as to produce a new one. Let us take the
case of a species of aquatic animals in a pond. The
scarcity of food caused by their multiplication will put
those in a more favourable position that can travel on
to the land and adopt a different diet. But if a large
number of the animals leave the water, there is no
longer any need for the others to become land-animals,
as they have now plenty of room and food. Natural
selection means pressure ; new species are only
formed when they must change in order to avoid
destruction.

This is quite clear when we consider the origin of
migratory birds. Here it was the migration that created
the species, the animals wandering into new regions for
which they needed new characters. Migration is an
important principle in the formation of species generally.
Thus the flying insects that reached certain small
islands lost their wings and became a new species,
because in this case natural selection always favoured
the worst fliers ; the good fliers were the first to tumble
into the water. Animals usually only rise to more

134 DARWINISM AND THE PROBLEMS OF LIFE

complicated and higher species when they reach special
localities. We shall see this in a later chapter.

The physical conditions of our planet are always
changing, it is true, and on this account the animals of
to-day are, generally speaking, different from those of
former times. But, on the one hand, there are un-
doubtedly spots on the earth in which the changes have
not been very great, such as certain parts of the deep
sea ; and, on the other hand, many animals can retain
their simple form in spite of considerable changes.
Thus we can understand why the very simple organisms
from which all living things have been developed are
still found in every drop of water.

We will inquire further into the conditions that bring
about the conversion of part of a species into a more
complicated one, and leave the other part at the same
stage of organisation. We have to- day not only the
final twigs of the tree of evolution. We have worms,
insects, vertebrates — in a word, living things at every
stage of organisation. But most animals have changed,
even when they have not gone beyond the range of this
fundamental form. The reptiles that live to-day differ
from those of former times, yet they are reptiles , and
only a part of them chanced to get into such special
conditions that birds were developed from them ; and
these were so favourably placed that they grew in
number and variety of species, as the new element they
had found had room for adaptation in the most diverse
directions. But geology tells us of animals that have
persisted in almost the same form for incalculable
periods ; and we must assume that some very exceptional

REPTILES AND AMPHIBIANS

135

conditions made this persistence possible. As a matter
of fact, such animals are very rare.

We must not say that the higher animals are better
adapted than the lower. Higher only means, in the
scientific sense, more complicated, not better. 1 he
bacilli that carry on the struggle of life and death with
man to-day show clearly how they, the lowest organisms,
have equipped themselves to meet the highest.

It is said that the Jurassic period was the age of
reptiles. That is not correct. There were far more
species that were not dependent on the giant lizards
than species that were. Was the swarm of insects, or
were the snails, subject to them ? And if we take their
size and variety as a symbol of predominance, we should
have to say that the whales and elephants are the lords
of the world to-day, if not the insects, which have more
species than all the other classes.

No animal species has ever dominated a period of
the earth’s development, since there were always other
creatures that were overlooked by them and had no
relation to them. It is only since the domination of
man began that we speak with some justice of a king
of nature, as his civilisation is able to alter the funda-
mental conditions of animal life. But even here we
are only partly correct. There are still countless species
of animals for whom this dominion has no meaning.

We come to the conclusion that the species that have
remained unchanged since remote ages have retained
their form because they had no enemy that compelled
them to change, and because within the limits of their
own species they grew to meet the physical conditions

136 DARWINISM AND THE PROBLEMS OF LIFE

of the period. They were never faced with the
alternative of changing or dying. If this alternative
had been forced on the generations very gradually,
and always in proportion to the possible latitude of
variation, we may confidently assume that they would
not have failed to meet it because of some necessity for
remaining unchanged.

We may also suppose that in all species of animals
any change is possible if there is time enough for it.
We are bound to admit this if our conception of the
organic world is a scientific one. The tenth and eleventh
chapters will tell us more of this. We will only say
for the present that every particle of living matter has
the tendency to vary. Every organ, every part of an
animal, may change ; and this change will in certain
circumstances become the basis for selection. How
much the structural plan of an animal may be trans-
formed is seen very well in the intestinal worms, some
of which have lost the alimentary canal altogether, and
take their food through the skin. The nearest character
will, of course, be used for change. And with what
enormously different means it may be effected is well
seen in the wings of animals. In bats and birds the
fore-limbs have been converted into organs of movement
in the air ; in the former the skin forms the air-beating
surface, in the latter the feathers. The birds come from
the reptiles — probably leaping reptiles. The feathers
had already been developed, as a warm covering, from
the scales, and amongst the leapers those certainly had
the advantage which had the longest quills on the fore-
limbs, so as to act as parachutes in falling. This was

REPTILES AND AMPHIBIANS

137

the beginning of the organ of flight, and it was steadily
improved. In this case the feathers afforded an easy
basis for the making of organs of aerial movement. In
the flying squirrel it was lateral folds of the skin ; also
in the flying reptile, in which they were further supported
by projecting ribs ; and in the flying fish the already
flattened breast-fins were converted into organs of flight.
The development of wings in the insects was very
different. In their case a small projection developed
at each side from the central body of the coat, and grew
into two horizontal plates ; with the central part of the
body these formed a sort of shield that carried them
through the air, like a parachute, when they leaped.
The insects were originally jumpers, as the lowest
species still are. But there are higher species, such as
the grasshoppers, that only use their wings for leaping,
so that we can well imagine that the insects that could
save themselves by the longest leaps away from their
enemy were those whose lateral plates were most exten-
sively developed. This use of the plates was fastened
on by natural selection for further development, and it
at last produced a joint by means of which the plates
could be worked backwards and forwards by muscles.
Thus the wings were made, and were modified in each
species in harmony with its vital conditions. 1

Let us return from the past to the present.

The actions of reptiles and amphibians are mainly

1 Other experts think that the wings of insects have been formed
from what are called their trachea-gills. These are small articulated
plates in the abdomen of May-fly larvoe that live in water, and serve for
breathing. But the wings are situated right in the middle of the
insect’s body, and so the theory given in the text is more probable.

138 DARWINISM AND THE PROBLEMS OF LIFE

determined by instincts, and they have therefore no
period of protected youth. When the little reptiles
issue from the eggs, which have been hatched under
the action of the sun’s rays in a moist place, they have
nothing to expect from their parents. All their instincts
are rigidly formed from the first ; their mobility is
considerable at once, and the young of the viper
have their deadly weapon, the poison, from the first
day.

Still, some of the reptiles, especially the lizards, have
a certain amount of intelligence. If a caterpillar creeps
across their path, they know that the victim cannot fly
away quickly, and they observe it with a certain
curiosity for some time. Then the head is suddenly
lifted up horizontally, and the snout, pointing down-
ward, pounces on the prey. It is crushed with rapid
movements of the jaws, brought into the right position
and swallowed, and the little tongue passes for some
time afterwards over the nose, as if it were smacking
its lips after the delicacy. A quicker insect, such as
a grasshopper, is not watched for some time, but is
captured at one swift bound.

The serpent takes a great deal more trouble in
capturing and swallowing his food. The smooth adder
seizes its prey, which generally consists of lizards, winds
itself quickly round it in three coils, lifts up its head,
and opens its jaws wide to swallow the head of the
victim. But the lizard also knows the only way in
which it can escape, and opens its mouth wide ; if the
snake approaches, it tries to seize its lower jaw, and if
it gets hold of it will not let it go until the snake

REPTILES AND AMPHIBIANS

139

releases it. Very large lizards often escape death in
this way.

The defenceless frog, on the other hand, is completely
at the mercy of its enemy, the ringed adder. When
one is after him, he makes desperate efforts to escape,
his usual measured jumps becoming gigantic in his
anxiety. A plaintive cry comes from his throat, and
he often abandons himself to his fate by crouching
down, when he is seized by the snake. If the snake
grasps his head the end is comparatively speedy, but it
often seizes the foot first. It then forces itself, as it
were, over the leg, its teeth gripping further and further
forward ; as these do not serve for masticating but
merely for holding, in the snake, and as they are
directed backwards, they easily allow anything to enter
the mouth but prevent it from dragging or falling out.
When one leg has disappeared down the snake’s throat,
it tries to grasp the other by a quick jerk, and if it
succeeds its teeth go farther over the frog’s body. The
head of the snake swells prodigiously, there is a last
desperate croak from the frog, and the jaws close over
it like a living tomb. Surprise is often felt that such
large frogs can be taken into the small head of the
snake, but it is capable of enormous distension at the
back ; the anatomic foundation of this is that the bones
of the lower jaw articulate with those of the upper jaw,
which are drawn out far behind, and enlarge the gullet
considerably when they open across.

Poisonous snakes go to work in a different way.
These hunt almost entirely during the night, as they
are generally nocturnal animals. The best way to catch

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DARWINISM AND THE PROBLEMS OF LIFE

the common viper is to make a fire in the wood at
night. The unusual light attracts them, and they
approach in amazement and stare curiously into the
flames. During the day-time they are sluggish, and
they coil themselves into a disk, with the head lifted
up threateningly when a man approaches. We do
not know much about the viper’s method of hunting,
but it is supposed that it gives the mouse, which is its
chief article of diet, a deadly bite, and lets it die before
swallowing it. It also penetrates into the dwellings of
the mice ; we can imagine the consternation of the little
creatures when they suddenly see their enemy’s eyes,
sparkling with death, before them in their holes, and
have no means of escape. There has been a good deal
of inquiry into the viper’s terrible weapon — the poison.
If the wound is immediately sucked out and bound up
the bite is not fatal, but there are frequent fainting-fits,
and the final symptoms of the disease only disappear
after six weeks. The best treatment of the wound is
with permanganate of potash, and an ancient and
constantly verified remedy is to drink a large quantity
of alcohol.

The movements of the serpent are peculiar. They
have no limbs, and can only glide along with the aid of
the whole body. This motion has been compared to
the progress of a rowing boat, because the serpent’s ribs
act like oars. The ribs articulate with the vertebral
column and have free terminations, but are connected
with muscles in such a way that they are pushed
forward and pulled back again, which gives rise to
serpentine motion. Other muscles, however, connect

REPTILES AND AMPHIBIANS

1 4 1

the ribs with the ventral plates, all of which end in
a sharp edge, directed inwards. Hence when a rib is
drawn forward, the edge of the corresponding ventral
scale is brought into a vertical position and must take a
grip in front ; on account of its sharpness it cannot slip
back, and when it is drawn to the body by the next
movement of the ribs, the body itself must slide forward.
By working the apparatus rapidly and extensively the
serpent advances quickly enough, but can, of course,
always be caught up by a human being. The lizards
also have the aid of this winding of the body in running,
and make use of the tail for the purpose ; hence a
lizard with a broken tail cannot get along nearly as
quickly as one that has the full use of that organ.

Everyone who has tried to catch one with the hand
knows that the lizard’s tail is easily broken off. If you
take hold of it by the tail, you will be sure to find this
quivering vigorously in your hand, and its former
possessor hurrying away without it. This is a great
advantage for the animal ; the number of tailless
lizards one sees in nature show best how often the
species is saved in this way. The chief enemy of the
lizards, the smooth adder, generally catches them by the
tail when it is after them ; and if the tail breaks off and
dances about in a lively way before the eyes of the
snake, the latter eats it and the lizard is saved. The
best way to catch lizards without injury is to take a long
grass-stalk, make a loop at the end of it, and slip it
carefully over the animal’s head. It does not suspect
its danger, and is captured by lifting up the stalk.

But nature, which has given this means of escaping

142 DARWINISM AND THE PROBLEMS OF LIFE

to the lizard, has also endowed it with the faculty of
creating a fresh one if it is lost. Three weeks after
the removal of the tail there is a leathery prominence at
the wound. This continues to grow, and forms a new
tail, which is so much like the old one that it takes an
expert eye to see the difference. However, the new
one never becomes as long as the old one, and it may
take two years to become perfectly similar to the old
one in colour and shape.

The faculty of re-making lost limbs is called
regeneration , and it forms a fitting transition from the
reptiles to the amphibia. These have an even greater
power of regeneration than the reptiles. It is true that
a frog’s legs do not grow again if they have been cut
off, as many peasants believe, when they throw the poor
creatures into the water again after amputating them ;
but the tailed relative of the frog, the newt, can
reproduce a great part of the body. Its legs grow
again when they have been cut off, the skin always
heals, and even a new eye is formed when one has been
torn out. The newts are exposed to the attacks of a
large number of enemies ; fishes, birds, and their own
relations, are continually after them, but it is especially
the large water-beetles that often clip off their legs with
their sharp jaws, or bite off an eye. Hence the power
of regeneration is confined to parts of the body which
are apt to be frequently lost in this way ; this happens
especially to the newt’s legs. The lizards are not
easily grasped by the leg by their enemies, and so this
has not the power to reproduce itself, as their tail has.

A poisonous snake is never seized by the tail, because

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143

every animal knows that the only way of avoiding the
fatal bite is to grasp it by the neck ; and as for most
animals, and a good many human beings, serpents are
always serpents, the dread is extended to the adder.
As a result of this we do not find the faculty of
regenerating the tail in any serpent.

Thus we see that the power of regeneration has been
developed by natural selection wherever it is necessary
— where a species is constantly exposed to mutilation.
This faculty is increased in proportion to the frequency
of the mutilations, and is not found at all where it would
be of no avail, where the enemies of a species destroy
the whole animal when they catch it. It is on this
account that we do not find any faculty of regeneration
in the frog ; its enemies do not tear off pieces of it, but
kill the whole animal, as we know to be the case with
the stork, ringed adder, fox, weasel, hedgehog, and
the innumerable other enemies of the frog. There is
one animal, however, that mutilates the frog before eating
it, and that is the tortoise. These approach the frog
from the depth of the pond, as it sits unsuspectingly
on the edge, seize it suddenly by the leg, drag it under
the water, get the leg as far down the throat as possible,
and then cut it off from the body with their sharp claws.
When they have swallowed the leg, they tear other
parts from their unfortunate victim, until nothing is left
but the skeleton. In this case it would certainly be an
advantage to the frog if it could escape after the loss
of one leg and form a new one. But it is exceptional
for a frog to be captured by a tortoise, partly because
they live chiefly on insects, snails, worms, fishes, and

144

DARWINISM AND THE PROBLEMS OF LIFE

salamanders ; partly because the animals themselves are
rare. Natural selection does not provide for exceptional
cases; it only brings about adaptations that meet average
needs. A character can only be preserved when the
majority of the animals that did not possess it would
come to grief on that account. When a particular
danger only threatens a species now and again, the
animal that escapes it through some peculiar character-
istic will have no prospect of bringing this to predominate
in the species generally. The characteristic in question
will soon disappear owing to crossing with others ; while
the majority, which do not possess it, will survive,
because the danger is too infrequent to cause it to be
selected. When we find in the animals that they only
react by adaptations against dangers that are common
in their life, this is an excellent proof of the operation
of natural selection.

We shall make the acquaintance in later chapters of
other animals that have a high power of regeneration,
but will for the moment cast another rapid glance at the
mammals and birds. If we bring before our minds the
enemies of the various species of these two classes,
their methods of attack, we see at once why they
generally have no faculty of regeneration. It is true
that the beak may be reproduced in the bird, and it is
this especially that is exposed to injury, as it is the
main implement and the weapon of the inhabitant of
the air. Further, the skin can be regenerated in
mammals ; and if a wound we have received were not
closed by scar-tissue, an infection by bacilli would
inevitably follow. And when we consider the absence

REPTILES AND AMPHIBIANS

H5

of regeneration in various parts of animals that have
otherwise a high power of regenerating, its origin as
an adaptive phenomenon becomes perfectly clear. The
newts that re-form eyes and legs cannot regenerate
internal organs. If we cut the lungs out of a triton,
or the ovary or any other internal organ, and sew it
together again, there is no regeneration of the part in
question. Why ? Because such a mutilation is hardly
possible in nature, and so could not be provided against.

While the newt has this admirable power of regenera-
tion to protect him against his enemies, the frog owes
its maintenance generally to its enormous fertility.
Their eggs, the familiar frog-spawn, are not only
poured into the water in large numbers, but are also
provided with a peculiar protective structure, which
consists of a jelly surrounding the egg. This jelly
prevents the eggs from being dried up or crushed, and
especially protects them from enemies. Birds, fishes,
crustaceans, and other animals are unable to eat the
eggs, because they slip out of the mouth again. Every-
one knows how difficult it is to handle frog-spawn.
The transparent balls of jelly also act as lenses for
focussing the rays of light, and thus attract movable
plants, such as certain algse, that produce oxygen,
which is good for the eggs. The jelly also lets the
rays of light pass direct to the eggs, and keeps them
there, so that they are practically surrounded by glass-
houses. The spawn is slightly heavier than water, and
if a high temperature causes an increased outflow of
gas from the plants, the bubbles collect on the spawn,
and bring it to the surface, where it receives the full

K

146 DARWINISM AND THE PROBLEMS OF LIFE

rays of the sun. When it is very cold, the outflow of
gas ceases, and the spawn sinks to the bottom of the
water, and is protected there from the wind and frost.

The wonderful contrivances of the frog-spawn show
that all the stages of the animal’s career are subject to
natural selection. Only those animals have a prospect
of transmitting their character to the next generation
which lay eggs that will escape the eye of the enemy
and the injury of bad weather. Whole pages might be
written on the adaptations of the eggs in the early
stages of the animals, and we shall see more about
them later on.

We must not leave the amphibians without drawing
attention to one of their best adaptations. This is the
character of their skin. It is not merely that this
represents the chief breathing-organ in this class, and
so enables a lungless frog to survive longer ; it also
affords the greatest protection to the animal. The
secretion of the cutaneous glands of the amphibians
is well known, and a good many legends have been
told of the salamander, which has been credited with
the power of remaining unhurt in fire. There is this
much truth in them, that the animal can remain for
some time over a gentle fire, as its glands give out
their secretion more freely under heat. But the pur-
pose of this juice is to disgust the enemies of the frog.
This is chiefly attained by the offensive smell, but
also by the corrosive nature of the fluid. The toad-
secretion is not poisonous for human beings, though
it causes inflammation if it touches the eyes, but it
may be fatal to small animals.

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147

Most of the amphibians that secrete offensive matter
are brightly coloured. The fire-salamander catches the
eye at once with its bright yellow spot on a black
ground, the newt or water-salamander has a yellow
belly, like the ringed snake ; the latter have been seen
to throw themselves on their backs at the approach of
danger, so that the yellow under-side is suddenly
presented to the astonished pursuer.

Light colouring is very common amongst malodorous
and poisonous animals and plants. Of plants we have,
for instance, the fox-glove, the laburnum, and many
poisonous fungi ; but as the flowers of most plants
are brightly coloured — for reasons that we shall see
in the sixth chapter — the poisonous flowers are not
very conspicuous. This is more the case with the
animals. Besides our amphibia, a number of malodor-
ous and nasty-tasting butterflies and many marine
polyps are brightly coloured. Offensive and poisonous
organisms show red or, more generally, yellow colours ;
it can hardly be a matter of chance that in the colour-
language of lovers yellow is regarded as a sign of hatred
and aversion.

It is easy to see why natural selection has given a
striking appearance to poisonous and obnoxious animals.
It is an advantage to them to be recognised at once as
inedible and dangerous. What use is it to an obnoxious
animal if the assailant does not know that it has a nasty
taste, and has to convince himself of it ? The victim
has generally to die under the test. So their poison is
of no use to poisonous organisms if their enemies do not
know them. The enemies die also after eating them,

I4§ DARWINISM AND THE PROBLEMS OF LIFE

but this is a revenge that cannot bring the slain animal
back to life.

In the case of many animals, such as the butterflies,
one bite is fatal, and hence those poisonous and ob-
noxious animals were always selected which were
calculated by their appearance to prevent enemies
from trying whether they were edible or not. It is
important, further, that all the marked animals should
have as nearly as possible the same indication. Then
carnivorous animals will not test the edibility of any
new offensive creature that crosses their path, but will
remember their experience of similar creatures and
leave it alone. Hence it is that so many poisonous
organisms have yellow colouring. There are even
edible animals with the colour because it affords
them protection ; the value of this adaptation, which
we will examine more closely in the sixth chapter, is
obvious. Possibly this is the explanation of the two
bright yellow spots at the back of the head of the
ringed adder, which have given occasion for the pretty
saying, that the snake, as the harmless creature is
popularly called, wears a crown.

Natural selection has also given many amphibians
a protective colouring, instead of the disgusting and
warning colours. A toad closely resembles a clod of
earth, the brown frog is not easy to distinguish from
the soil, and the tree-frog can hardly be detected in the
green foliage. The latter can change its colour — not
voluntarily, but it assumes shades from brown to green
according to its disposition, the weather, and the
environment.

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149

The amphibians and reptiles may live for a consider-
able number of years, though our own species are not
so ancient as the crocodile, of which the blacks say there
are specimens that have sunned themselves on the same
sand-bank day after day as far back as the memory of
their fathers and grandfathers goes. It seems, however,
that the tortoise may live for a hundred years, and toads
have been kept in confinement for thirty-six years ; they
are not infrequently kept, as they are the most
intelligent of the amphibia, and sometimes answer to
their names. But the stories of toads living for decades
inside blocks of stone must be relegated to the realm of
fables. It is true that they can go a long time without
food, and a much longer time with little food ; this is
due to their almost perfect digestion. But air and
moisture are absolutely necessary for them.

It may happen that a toad falls into the shaft of a well
during its nocturnal rambles, and, while its companions
hunt and love and rear their progeny in the garden and
the field, it is condemned to maintain a pitiful existence
on a few insects, and so may become as “old as the
hills.”

Even the animal has its destiny.

CHAPTER V

FISHES

Origin of terrestrial vertebrates and of lungs. Similarities in the
structure of animals. Transformation of organs. Creation
or evolution ? Many animals are worse off than others.

Selection only creates what is necessary. Atrophy of useless
organs. Rudimentary organs in man. Degeneration of organs
by panmixis. Indifferent characteristics of animals. The

differences between species are adaptations. Correlation.
Animals that are beyond the range of selection. Qualities and
quantities. Explanation of atrophied organs by economy of
sustenance and negative selection. Impossible to explain many
rudimentary organs. The biogenetic law. Gills in the human
embryo. Predatory fishes. The rhodeus and the pond-mussel.
Senses of fishes, their dangers. History of the eel and the
salmon. Artificial selection of fishes.

As we make our way down from the sunny heights of
the forest-crowned hills to the green valley, we often
halt for a moment, when our eye falls on the brook by
the way, and catches sight of a trout. We admire the
ease and restfulness with which the animal meets the
rush of the water over the stones.

But there is something more wonderful in the power

of the fish to penetrate into the depths of the sea, and

remain there without any exertion of the muscles. As

a fact, the fish can halt at any depth without moving a

fin ; it has a special organ that enables it to do this.

The swimming-bladder is the name of this organ, and

IS©

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151

anybody who has ever killed a fish will remember the
large structure filled with air. The bladder is sur-
rounded by muscles, and when it is compressed by
these the fish descends in the water. As the fish has
about the same specific gravity 1 as the water, it becomes
heavier when the air in the bladder is compressed, and
so descends ; when the pressure is relaxed, the air
expands in the bladder, the volume of the fish is
increased, it is specifically lighter, and it rises to the
surface. Pressure on the front part of the bladder
causes the head to sink ; pressure at the back sends
down the tail.

In about half the species of fishes the bladder is
connected with the gullet by a duct. This is especially
developed in the dipneust or mud-fishes, which live in
tropical waters that dry up in the rainless season. In
many species the bladder is double. When the water
disappears from the pond they live in, and they find
themselves on the mud, the bladder takes over the
function of breathing from the now useless gills. They
absorb the oxygen from the air that presses into the
bladder through the gullet, while the carbonic acid that
must be given off from the fish’s body passes away by
the bladder and its duct.

The mud-fishes are most interesting to us, because
they show that an organ which seems to make its
appearance suddenly in the land-vertebrates is really
found in a rudimentary form in the fishes. If we had
not the mud-fishes, we should scarcely be able to

1 The reader will know that we mean by specific gravity the number
of times that a body is heavier than an equal volume of water.

152 DARWINISM AND THE PROBLEMS OF LIFE

imagine how the first land-animals could breathe, as
they would need an organ in some proportion to their
size. How could this be formed so quickly, seeing that
natural selection only builds up gradually from small
beginnings? The mud -fishes remove the difficulty.
They afford most striking testimony to the theory of
evolution and natural selection, as they show that where
selection required a large organ as the beginning of the
lungs, it was forthcoming. It is well for us that in
the peculiar localities where land-animals arose some
of the transitional forms are still preserved ; the more
so as geology could give us no information on the
transformation, since soft parts are never fossilised . 1

The transition from the fishes to the amphibians is
seen, not only in the mud-fishes, but in the develop-
ment of every frog and salamander. The larvae of
the amphibians, when they issue from the egg,
breathe by gills, which closely resemble those of the
mud -fishes. In fact, the whole organisation of the
larvae is closer to that of the fish than to the adult
of the species they belong to.

Even the adult amphibians very much resemble the
fishes ; all vertebrates must do so, in fact, if they
have descended from the fishes. We know how

natural selection, which must have brought about the
transformation, works. Variations in different organs
of the parent species, which are trifling at first, are
emphasised in the course of several generations.

1 There are, however, recent experts who think the lungs were
formed, not from the swimming-bladder, but from sac-shaped folds
or outgrowths of the fore-part of the gut.

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153

Hence in the comparatively brief period — geologically
speaking — since the appearance of the fishes, no
species could be developed from them with a
fundamentally different structure from their ancestors.

There are no organisms that descend from the verte-
brates, and differ from them so widely, as the fishes
do from the insects ; the chief reason is, that there
has not been sufficient time for such a transformation.

We can understand, therefore, why the structure of
all vertebrates is essentially the same. All of them
have an internal skeleton, and have the organs of
nutrition and reproduction on the ventral side, and
the nervous system on the dorsal side. But the
similarity goes still further, and this also is clearly
the effect of natural selection. Selection always
builds on a given material ; it makes use of actual
adaptations, preserves them when change is un-
necessary, and modifies them when some new adapta-
tion of the species requires it. If, for instance, there
was already amongst the fishes a skull with the
function of protecting the brain, there was no need
for the formation of a new structure to contain the
ever-growing brain in the classes that developed from
the fishes. Therefore, the bones of the fish’s skull
were retained in the new classes, and were enlarged
and modified according to need. As a fact, even the
human skull is generally composed of the same bony
plates that we find in the fishes. It is well known that
students used to be puzzled by the fact of the upper
jaw of all vertebrates containing four pieces of bone,
while in man it had only two, until Goethe discovered

154 DARWINISM AND THE PROBLEMS OF LIFE

the two “ intermaxillary bones ” in the child, and
showed that they fuse together in the adult, and
cannot be distinguished any longer from the other
two jaw-bones.

It is the constant practice of natural selection to
build on actual material, and that is the quickest way
of accomplishing anything. Hence, when the amphibia
took to living on land, and needed support for the
body and organs of locomotion, the four fins of the
fish were converted into the limbs of the land animal.
In the lower fishes the joint of the jaws is formed of
two bones, which are replaced in the higher ones by
a greater development of the articulating bones. The
abandoned bones are found in the higher animals
only in the internal ear, where they still form a joint
as the “hammer” and the “anvil”; but instead of
mastication, it serves for conducting sound.

We could show that nearly all the organs of the
vertebrates are found in all the five classes, and have
always the same fundamental form and structure. We
have seen in the previous chapter that Darwinism
explains these similarities, great and small, by the
law of heredity. The children of a certain couple of
human parents are more like each other than their
children will be — or brothers and sisters are more
like each other than cousins — and it is just the same
with animals. Birds are nearer to reptiles than to
amphibians, because if we look upon the actual
reptiles as brothers of the actual birds, the actual
amphibians will be their cousins. It was from leptiles
that the birds descended, and the ancestors of all

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155

reptiles consisted of a pair of amphibians that reached
special conditions, and so their offspring formed a
new class. These amphibians lived about the end
of the Carboniferous period. Their ancestry coincides
with that of the other amphibians living at the time,
whose descendants are found in our frogs and
salamanders ; earlier still, it is a pair of fish ancestors
that led to the beginning of the amphibians in a
particular locality.

This similarity of organisms is a hopeless puzzle
for the theory that all our animals were created
separately. On that theory it is unintelligible why
some animals so closely resemble others in structure,
others still more, and others not at all. It can give
no explanation of these facts. Moreover, it cannot
explain why certain species seem to be in a much
worse position than others. Thus, for instance, the
circulation of the blood is clearly worse in the frog
than in the bird. The frogs have only one chamber
to the heart, and this has to receive both the used-
up blood from the body and the fresh blood from the
lungs with its new oxygen. The blood mixes in the
single chamber, and the body is not supplied entirely
with fresh blood, but with the mixed fluid, which
passes from the heart into the body. In the bird
the chamber is divided by a partition ; the fresh
blood from the lungs passes into the left half, and
is conveyed in its purity from this to the body, while
the right chamber receives the used - up blood and
drives it to the lungs to be renewed.

The birds, with their constant supply of pure blood,

156 DARWINISM AND THE PROBLEMS OF LIFE

are obviously better off than the frogs, in which the
oxidised blood that should go to the body is always
mixed with the bad. Why were the frogs placed at
this disadvantage at creation? Have they less right
than the birds to a good constitution ?

Natural selection explains the riddle. From the
heart of the frog has been developed that of the
amphibian, then that of the reptile, and from this
in turn that of the bird. When the amphibians
appeared, the heart was at the stage of development
in which we still find it in that class. This structure
sufficed for those descendants that remained amphibians,
but not for those that became reptiles and birds.
In the case of the latter, the heart had to be improved,
because the more energetic vitality of the two new
classes required a better supply of blood. Natural
selection only produces what is necessary ; the amphi-
bians had to retain the old heart, because they did
not need a more advanced one.

But all the organs cannot be retained when a
species is transformed into a different one.

When complete land-animals had been formed from
the fishes, the gills became useless. In fact, they
would be injurious to the new organisms, as they
perforate the sides of the gullet, and would allow
foreign bodies to pass too easily into it. Thus, for
instance, it often happens to the greedy perch that his
prey sticks in his gills from trying to swallow it too
quickly, and both animals perish. As soon, therefore,
as the gill-clefts ceased to be absolutely necessary for
breathing, they had to be got rid of by natural

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157

selection on account of their dangers, which were
increased by life on land. Here we have for the
first time the negative action of natural selection. We
see that it can not only create new organs, but also
destroy actual ones when this becomes necessary for
their possessor.

It often happens that when an organ has to be
adapted to a new function parts of it will degenerate.

When the fore - extremity of the reptile was con-
verted into a wing in its descendants, the birds, it
was useful to the latter to have the new organ in one
piece , in order to work it like an oar. Projecting
fingers would have offered resistance to the air, and
would have brought continual wounds to the bird by
getting broken off. Hence, in the interest of the
flying-organ, the fingers had to disappear. As a
matter of fact, in the bird’s wing to - day we find
only the rudiments of five fingers, though the archae-
opteryx had them well developed and active. There
are plenty of instances of a similar decay in the
interest of a unified support ; amongst others, we
might mention the leg of the birds and the ungulates.
What seems to be the knee in the fore - leg of the
horse corresponds to our wrist. The large bone that
passes from this to the joint of the hoof is the upper
part of the middle finger ; it has been developed to
this extent because it can bear the weight of the body
better as a single support. But at the side of it we
find two other small bones, which are attached to the
joint above, and are called the styloid bones. They
have no function, and cannot be understood except

158 DARWINISM AND THE PROBLEMS OF LIFE

as relics of the second and fourth fingers ; we can
recognise them as such the more confidently as we
can trace in geology every stage in the gradual
degeneration of these fingers in the horse’s ancestors.
These degenerate structures are known as rudimentary
organs ; they lend great support to the theory of
evolution. If the animals were created separately,
why were they endowed with these quite useless
appendages? We can only understand them when
we admit that they were fully developed and useful,
in the ancestors of the particular animal, and that in
their descendants, which had no further use for them,
owing to change of habits, they could not entirely
disappear, because the animals had inherited them
and transmitted them in their turn.

We find rudimentary organs of this kind in almost
every species of animals. Man himself has a large
number of them — nearly a hundred. Amongst others
there are the last two ribs, the wisdom-teeth, a process
of the shoulder-blade — the caracoideum, a vesicle in the
brain that we call the pineal body, and the worm-
shaped appendage of the ccecum. The latter is not
only superfluous, but even dangerous, on account of
the inflammation (appendicitis) that may be set up in
it by the penetration of foreign bodies. There were
vegetarian mammals amongst our ancestors. And in
plant-eaters the coecum is often indispensable, and is
often longer than the whole body of the animal.

In the same way the caracoid process of our shoulder-
blade is an important bone in reptiles, amphibians, and
birds ; and in the pineal body we have the last relic of a

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159

cyclopean eye that was used by the ancient amphibians,
and resembles a small eye in a certain living reptile in
New Zealand. The more we examine the anatomy of
the animals, the more rudimentary organs we discover.
In the whale the pelvis and hind-limbs remain as
shrunken relics buried in the flesh ; and amongst the
serpents there are species that still show rudiments
of the pelvis.

In the case of many of these organs the reduction is
due to natural selection, which has a much greater
significance in this direction than most experts admit.
But it does not explain every case ; above all, we can
only understand with its aid how an organ can be
reduced to a body that is indifferent for the life-
purposes of an organism. We have already spoken of
those island-dwelling insects that have had their wings
reduced to small relics, because those that could fly well
were too frequently carried by the wind into the sea.
In this case natural selection had to reduce the wings
until the insects could not raise themselves with them
any longer. There its function ceased. It could not
make the wings any smaller, because if no insect could
fly any longer, there was no ground for selection, and
for the function of flight — the sole cause of selection — it
was a matter of complete indifference whether or no
the wings were reduced by another fraction of an inch.

There are also insects in Europe that never fly.
These are the females of most of the bombycidae.
When they emerge from the pupa-covering, they remain
in the same spot, and are sought and fertilised by the
active males, and then lay their eggs. The reason for

l6o DARWINISM AND THE PROBLEMS OF LIFE

this peculiar instinct may be that, in the first place, the
animal, which is well adapted to the bark of the tree,
protects itself and its eggs best by remaining still ; and,
secondly, that the body is too much burdened with
e gg s to be able to fly. If it is better for the animal not
to fly, this instinct suffices to prevent it, and natural
selection has no occasion to reduce the wings, as has
been done with some of the silk- worms, such' as the
orgyia, the wings of which have shrunk into small
relics. But if the disuse of flight depends only on the
overloading of the body with eggs, we do not very well
understand the reduction of the wings at first sight.
Can it be useful for the butterfly to have the nourish-
ment that usually goes to the wings diverted to the
rest of the body and the eggs ? When we remember
the enormous multiplication of the black arches which
still have wings of the full size, we shall not attach much
value to this economy of food. Nor can we quite
admit, in the case of the whale, that those individuals
always had an advantage whose hind-limbs were a trifle
shorter than those of their comrades, and so required
slightly less food. In view of the enormous mass of
muscle and fat in the colossus, this slight economy
could never become a matter of life and death, even if
it is useful at all to the other organs.

But, we may further ask, is natural selection bound
actively to reduce an organ that has fallen into disuse ?
Do we not know that such an organ must deteriorate
when selection ceases to affect it ? Every organ only
advances from the fact that the individuals that have it
in a poorer form are destroyed. When it becomes a

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matter of no consequence whether an organ is in good
or bad condition, those animals will survive and repro-
duce who have it in an inferior form ; this inferior organ
will be transmitted to the young, and the number of
individuals of that kind will increase in every generation.
For instance, there is no need for civilised man to have
good eyes. Those with poor sight can earn their bread
and bring up a family, by using glasses or adopting a
field of work in which shortsightedness does not count.

This process, in virtue of which even the inferior
specimens are preserved, reproduce, cross constantly
with the others, and so affect each generation more and
more, when natural selection ceases, was first pointed
out by Weismann and given the name of panmixis . But
the effect of panmixis is not as simple as it seems
at first sight, and it must not be exaggerated. It
cannot bring about the reduction, but only degeneration
of an organ. We will now see how this takes place.

In a complicated organ, such as the eye, for instance,
a number of different parts co-operate to discharge its
particular function. All these parts form a harmonious
whole, and if the organ is to be improved, they must all
be modified in the same direction. An orofan of this
kind is like a regiment of soldiers marching in rank and
file. Order is only preserved as long as each individual
remains in his place, or moves just in the same way as
the rest. If one marches in one direction, another in
another, the unity of the whole is destroyed, and the
greatest confusion prevails.

The harmony of the parts of an organ is secured
by natural selection. The parts of the eye vary like

1 62 DARWINISM AND THE PROBLEMS OF LIFE

every other living thing. If the eye is to retain its
efficacy, no part must be greatly altered unless the other
parts change in the same sense. If one of the parts of
the eye is suddenly and separately developed in an
animal that absolutely needs good sight, it fails in the
struggle for existence, and with it disappears the
inharmoniously developed eye. There is only one way
of improving the eye, but there are plenty of ways of
spoiling it. Hence if selection no longer watches over
the harmony of an organ, each part will vary on its own
account ; one part will advance in this direction,
another in that, and the end of it will be the spoiling
of the whole organ.

It is clear, then, that panmixis, or the mixture of all
possible animal variations without weeding out the bad
ones, must lead to the degeneration of an organ. But
does an organ become smaller when selection ceases to
act ? Diminution of size is the chief characteristic of
rudimentary organs.

Certainly, when natural selection no longer prevents
the reduction of an organ by cutting off all variations
towards diminution, these will persist and be transmitted
like the rest. But are there not always variations in
the direction of increased size ? Why should the
reducing tendencies suddenly prevail ? Natural
selection cannot influence variations ; it can only
accept or reject those that are offered to it.

As a matter of fact, it has been proved beyond
question by a number of investigations that variations
towards increase and decrease — plus and minus
variations, as we call them — are as a rule equal in

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number. Hence if selection ceases to weed out the
one group, all the animals will come to reproduce and
cross with each other ; in the general mixture the plus
and minus will neutralise each other. The larger
variations cannot prevail in the succeeding generations,
because they are affected by just the same number of
smaller variations. An organ that is subjected to
panmixis will thus become neither smaller nor larger,
but remain of the same size. It will become one of
what are called the indifferent marks of the particular
species — a mark that has no connection with the
essential life of the animal, yet is tenaciously retained in
the structure. Are there any of these indifferent marks
in the organic world ?

In the first place, it is always precarious to describe
certain characters of animals as indifferent. In earlier
years all that we have recognised to-day as adaptation
was regarded as a mere mark of the species. Every
year there are fresh discoveries of adaptations ; we are
constantly finding an important vital significance in
parts of animals that had been regarded as of no
consequence whatever,

Nevertheless, they may be indifferent organs, and
we can easily imagine how they may arise. When one
species is formed from another, a whole series of organs
are modified to meet the new conditions. But the new
species will also inherit from the parent species features
that were necessary to the ancestors in their particular
conditions, but have no use in the new environment.

If these organs were in the way of the new life, they
would, like the gills of the fish and the fingers on the

164 DARWINISM AND THE PROBLEMS OF LIFE

bird’s wing, be reduced by natural selection until they
were harmless ; but if they were of no consequence
either way to the new species, they would remain
unchanged in size, because their plus and minus
variations would neutralise each other. They would
only change their size in the event of the total size
of the new species having to be altered.

The province we have now entered is a very delicate
one, because, as I said above, we can never know
whether a characteristic of an animal, the use of which
is not visible, may not be indispensable all the same.
In any case, it is certain that indifferent features do not
form the chief criteria of species and classes, as has been
said ; nor is it true that the adaptations are not con-
cerned in the discrimination of species. It has been
justly replied to these writers that it is precisely the
adaptations that constitute the species or the class as
such. What else is left in the whale if we take away
its adaptation to aquatic life ? What becomes of the
bird, which, as we saw above, consists entirely of
adaptations to aerial life? If we look at species in
this way, we feel inclined to say that there is nothing
indifferent in an animal.

Hence we see the rise of new species especially
in the selection of new adaptations. In this, in-
different organs may be taken over ; in fact, it is
possible for them to appear for the first time. Darwin
himself established a law that he called the law of
correlation. According to this, the various parts of
the animal body mutually affect each other in growth.
Everybody knows, as a matter of fact, that organs that

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seem to have nothing to do with each other may
influence each other. Thus, when a man is emasculated,
he retains the high voice of the boy, and never grows a
beard. Women who are about to become mothers
suffer from nausea, vomiting, and a number of other
afflictions. In a word, we have numerous proofs of the
co-operation of different parts of the body.

Thus, when an organ has been adapted to new
conditions and modified in the making of a new
species, a structure may arise in another part of the
body from a chain of causes that escapes our scrutiny.
We put chandeliers in our rooms to light them, for
instance. But we heat them at the same time, as well
as illuminate them. This is a constant and necessary
concomitant of the lighting. We had no intention of
causing it, but we have to reckon with it because we
cannot have the gas-light without it . 1

Owing to correlation many organs may be preserved
that are of no consequence to the animal’s life. Other
and important organs prevent them from changing their
dimensions or quality, because they are in some way or
other connected with them, and as they themselves must
remain in the interest of the species, they retain the
others with them. However, we will make as little use
as possible of this principle of correlation, because we
know little about the mutual relations in the animal
body, and so the whole principle is not well grounded

1 Many writers explain in this way the colours of the various races
of men. They think it is a necessary concomitant of the adaptation
of the skin to different degrees of heat ; the skin does, in point of fact,
behave differently in relation to perspiration and immunity against
fever.

1 66 DARWINISM AND THE PROBLEMS OF LIFE

on facts, and lends itself to abuse and misuse in all sorts
of cases. Many Darwinians hide behind this principle
whenever they cannot discover real explanations.

We saw that an organ from which natural selection
has removed its hand remains of the same size, but
deteriorates in quality. How is it with an animal that
is outside the range of selection? We see this in the
case of our domestic animals. Apart from cattle,
horses, pigs, and fowls, and especially dogs, of which
we produce larger and smaller races by artificial
selection, and the organs of which have been modified
by selection, we see that, as a matter of fact, the size
of domestic animals generally remains the same. Take,
for instance, the cat, the fallow deer, and the common
pigeon that is found on every roof. The parts of these
animals scarcely change in size, though they do in
another particular — colour. The reason of this is that
qualities do not vary in two opposite directions, that
neutralise each other in crossing, but in several. Still,
there are colours the microscopic structure of which
compels them to appear either in a light or a dark
shade, and these will be preserved in panmixis.

As a general rule, however, the colours of animals
must be preserved by natural selection ; this is seen in
many wild as well as tame animals, the variations in the
colour of which clearly involve no danger to the species.
Take the varying colours of the common viper, or those
of the male hedge-lizard. But there are also colours in
which variation is only possible in one direction so that
they can never be neutralised. The Alpine hare is
pure white ; and as there is nothing whiter than white,

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all shades of this animal’s colour must be darker. Here
we have a clear case where natural selection keeps a
thing at a certain height. As a general rule, we do not
find it to do this, but to tend upivards } Nothing is
absolutely good. The eye of the mammal seems good
to us, but the bird shows that there are better ones.
However, even if selection remains at a certain level
in the case of many qualities, it certainly never does
that with quantities, as in that case it would have to
weed out plus and minus variations. But as these
neutralise each other by panmixis, there is no need
for the action of natural selection.

We know now, therefore, that panmixis cannot reduce
the size of an organ. How, then, can we explain the
rudimentary organs ?

This would be easiest to do, it is clear, with the
Lamarckian principle. The organ that is no longer
necessary, this theory would say, is no longer used.
It grows weaker and weaker by the disuse, and is
transmitted to offspring in an enfeebled condition.
This continues until the organ entirely disappears owing
to the steady inheritance of the results of disuse.

But we saw above that the wings of the blue-throated
warbler, though they are not used, are found in each
individual of the strength and size that the long migra-
tion requires. This circumstance led us to distrust the
Lamarckian principle, and as we shall conclude in the
sixth chapter that it is completely untenable, we will not
delay with it now, but try to explain the rudimentary
organs by other means.

1 Or, of course, downwards.

DARWINISM AND THE PROBLEMS OF LIFE

1 68

We have already recognised the significance of
selection in the reduction of organs. I may remind
the reader of the wings of the island-insects and the
fingers of the bird. There are snails, too, with small
shells right at the posterior end. They feed on earth-
worms, and it is possible that their malformation is due
to the fact that the snails with the smallest shells were
best able to follow their prey into their holes. There
may be many cases that selection can explain, but
as we saw, it cannot explain all the rudimentary
organs.

Another principle is that of economy of nourishment.
Every animal, it says, has a limited amount of nourish-
ment in its body, and if one of its organs is to grow
bigger, the material for it must be taken from another
part of the body. If, for instance, in a certain species
the strongest possible support for the body is required,
as in swift-running animals of a certain weight, the shin-
bone must become thicker, as this is always the chief
support of the body. In that case natural selection will
always choose the animals with the strongest shin-bones
(tibiae), and possibly at the same time, indirectly, select
smaller calf-bones (fibulae) — if, namely, the shin-bone
has obtained its increase in size at the expense of the
fibula. Now, there is certainly only a limited quantity
of nourishment in the bones, and it seems possible that
for one bone to become larger it must take the food that
would have gone to the other bone. In this way the
continuous selection of strong shin-bones might gradually
bring down the fibula to the dimensions it actually has
in the horse and the bird.

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But on the other hand, any animal can take up a
position without displacing another one, and we can
imao-ine cases in which, when variations occur in the
tibia and fibula, the former may be larger and the latter
no smaller, or both bones may be stronger. Such
variations have then a greater quantity of nourishment
in the body. But perhaps the growth of the tibia at
the expense of the fibula is the most frequent and
normal variation, and natural selection had especially to
deal with individuals that had a larger tibia and smaller
fibula. If such variations were more common than those
that had the greater amount of nourishment, the fibula
would be bound gradually to disappear.

We might give a further extension to our principle,
and say that nature always chooses the nearest way ;
and appeal to physical forces that also do this. In that
case the body would be bound first to use up the already
existing and now superfluous elements in its further
construction. Yet when we reflect that, on this as-
sumption, many indifferent characters must disappear,
we shall not be too hasty in applying our principle.
We have as yet made so little progress in studying the
nature of the body ! We must, therefore, modestly
admit that our actual knowledge is not sufficient to
explain the rudimentary organs. Selection and economy
in food may be the cause of the reduction of a good
many organs, but certainly not of all ; and panmixis only
explains the deterioration, not the diminution, of an
organ. Weismann has recently tried to enlarge
panmixis with his theory of germinal selection, and
has credited this with the power of making organs

170 DARWINISM AND THE PROBLEMS OF LIFE

rudimentary. But we shall see later on that we cannot
accept this principle.

However, there has been one result from our inquiry.
Although we were unable to discover the causes that
account for the rudimentary organs, their existence is a
convincing proof of the theory of evolution. We cannot
understand the existence of these useless organs unless
we suppose that they had a purpose in the ancestors of
their possessor, and were then fully developed ; and
that they had to be transmitted steadily to posterity by
the force of heredity. These useless appendages can
never be reconciled with a theory of creation.

Still greater is the testimony to the evolution of
organisms of the rudimentary organs that appear and
disappear in the lifetime of an animal.

We said at the beginning of this chapter that an
amphibian shows, in the course of its early development
from an aquatic to a terrestrial animal, how a salamander
or a frog must have evolved from a fish in past ages.
We find similar reproductions of its evolutionary history
in ancient times more or less in the embryonic develop-
ment of every animal. All living things descend from
protozoa, the microscopic beings that we find in a drop
of water ; and every animal begins its life at the same
stage, since the ovum entirely resembles one of these
protozoa. After the protozoa came the polyps, from
these the worms, and from these again the fishes. Now
we find in the development of every vertebrate ovum,
including the human, stages that may be compared with
those three forms. Haeckel gave the name of “the
biogenetic law” to this phenomenon, and attached a

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very great importance to it. It is believed to complete
our geological discoveries. Just as the various epochs
in the earth’s growth show first lower then higher
organisms, so we find the same gradation once more, in
a condensed form, recapitulated in the embryonic
development of every animal.

We shall deal more fully with the significance of the
biogenetic law in the seventh chapter. Here we will
only point out by means of it why rudimentary organs
appear and disappear in the evolution of animals. This
we find to be the case. The human ovum needs nine
months for its development. In the fourth week it has
made considerable progress, but is very unlike a human
being, and much more like an animal. It clearly shows
slits like the gill-clefts of the fish on each side, and has
a striking resemblance to the fish in the arrangement
of the heart, the blood-vessels, and the bony skeleton.
The clefts are of no use whatever to the unborn child,
and they soon disappear again. We may confidently
say that there is no stronger proof of man’s descent
from the fish than these gill-clefts , which are still
retained in the descendants of the fish — men — in
virtue of the law of heredity, although they have
had no purpose or use for millions of years, and they
disappear in the further course of development.

Thus we have got back to the fishes from which we
started. They are not only of importance as the lowest
class of vertebrates on account of their structure, but
their life gives us an interesting illustration of the
working of natural selection. The struggle for life is
found amongst them in unsparing form. Except the

1 7 2 DARWINISM AND THE PROBLEMS OF LIFE

white fishes which feed on green plants, and the carps
that stick their heads in the mud to find the plants, and
especially tiny animals, they are all predatory animals,
and do not even spare their own species. Anglers have
often found a pike in the stomach of another one, and a
third pike inside the second one. The pike is the most
voracious of the fishes, and is rightly described as the
shark of inland waters. It is even dangerous to small
ducks ; and young sand-martins, sitting on a branch over
the water, often find their grave in its stomach. It has
even been seen to suffocate swans by dragging them
under water. It is from one to two yards long, and
weighs up to 70 pounds. It generally chooses the night
for its predatory excursions. During the day it hides
amongst vegetation, and only waylays an occasional
victim. If one comes near it, it darts out, gets its
fang-teeth into it, releases, and then grasps again and
swallows it. If the victim hurries away, it leaps after
it, and is very active in every respect. It fears only
the stickle-back and the perch, on account of their
spikes ; but it sometimes captures even the perch, and
holds it until its spikes drop from exhaustion, and then
swallows it.

The perch itself, however, comes next to the pike in
voracity. It waylays small fishes behind the pillars of
bridges or at the edge. When a swarm of small fishes
approaches, it darts amongst them like a hawk, and
seizes its victim. The perch-pike is less murderous ; in
spite of its size, it is not as quick as the ordinary perch,
and its gullet is not expansive enough to take in large
pieces. But the smooth eel-pout, with flat head and

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wicked-looking eyes, is the companion of the pike and
perch in slaughter. It waits until dark in the thickest
vegetation in clear, swift-running water. Then it glides
slowly along, using every stone and piece of wood as
cover, towards the edge ; it leaves no cover unsearched,
and darts like an arrow on everything that is eatable.
The most comprehensive predatory of German waters
is the shad. It grows to a length of four-and-a-half
yards, and weighs up to 400 pounds. This is another
nocturnal fish, but its bristles can also be seen moving
about in search of prey during the day. It eats ducks,
and even dogs, and the bodies of children ; even living
children have to beware of it, as the inhabitants of the
Danube provinces, where it is still often found, know.
Much larger, but much less dangerous, is the sturgeon,
which gives the best caviare. It grows to a length of
eight yards, and weighs sometimes 1,000 pounds. With
the equally large and harmless giant-shark, it is the
biggest fish on the earth.

The small fishes have their revenge on the larger
ones by eating them in their early stages, and so
prevent them from increasing too much to their own
cost. When the trout has cast its spawn, the bullhead
gets to work. It places itself vertically over the eggs
with its head down, makes them rise by a movement
of its fins, and swallows them one after another. The
trout in turn has a taste for the young bullhead ; we
always find the bullhead in a stream which contains
trout, or vice versa. They keep each other balanced.

The means by which fishes protect themselves
against enemies are very varied. The harmless tench

174 DARWINISM AND THE PROBLEMS OF LIFE

buries itself in the mud ; the bullhead expands its
gill-covers so that the spines stand out ; the perch
elevates its spine-fin, and in the stickle-back the spines
are raised in a fixed joint so that it does not lower its
weapons even after death. In this way it is safe from
most enemies ; only the salmon and torsk can swallow
it with impunity. It can also protect its young. The
male, which is the more lively of the two sexes in this
species, and reveals every emotion by a pretty play of
colour, builds a nest of root-fibres and vegetable matter
which he glues together with a sticky substance that
oozes from his sex-opening. Then, by a show of colour,
by graceful movements, and, if that does not avail, by
pushes, he induces a female to lay its 68-80 eggs in the
nest. When that has been done, the male seeks other
females to fill up his nest ; and when he thinks he has
enough eggs, he improves the nest, and watches it most
carefully. Every creature that comes near is furiously
driven off ; these are generally of his own species, as
they have a great liking for the eggs. His watchfulness
doubles when the little stickle-backs appear. They swim
away over and over again, and he brings them back in
his mouth, and puts them back in the nest. He does
not relax his care until the young can easily support
themselves, and then he leaves them.

The bullhead also defends the eggs and the young
for some time, and the way the Rhodeus amarus takes
care of its young is most peculiar. This is one of the
prettiest of German fishes on account of its graceful
movements, and the male has also such glowing colours
in the spawning season that the whole animal seems to

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175

be lit up by an internal fire. The female is recognisable
at this time by a long ovipositor, into which it forces an
egg or ovum. With this it swims to one of the larger
painter’s gapers, which stretch out their respiratory and
cloaca - opening sluggishly from the sand. The fish
drops its ovum into this, and the male, its whole body
quivering, pours its seed over it. The mussel tries to
get rid of the unwelcome foreign body by violent con-
tractions, but does not succeed as a rule. The egg
passes into its gill-chamber, and the little creature that
develops from it forms a sort of transverse swelling
behind its head, with two processes that help it to
strengthen its hold. These projections afterwards
disappear and the fish abandons the home of its
childhood, which had sheltered it completely from
danger.

But the mussel has its revenge for this involuntary
shelter. When the hour comes for its reproduction,
it thrusts out its brood through the opening. The
young mussels fall to the bottom of the water, open
the shell, and send out a long thread. This has a
sticky surface, and gets entangled with the threads of
other young mussels, so as to form a firm and com-
plicated net, from which the little animals hang. If
a fish — it is generally a rhodeus or a perch — runs
into the net, the mussels come into contact with its
body, and immediately bring their shells together,
and the sharp edges press deep into its flesh. A
growth is formed in the skin of the fish at the injured
spot, and at length covers the whole mussel. It then
lives at the expense of the fish, though it does not

176 DARWINISM AND THE PROBLEMS OF LIFE

do it much injury on account of its smallness. Its
organs are gradually developed, and when it is quite
ready it releases itself by vigorous movements from
the skin, and follows the adult life of its species at
the bottom of the water. It is a remarkable and
interesting correlation of two very different animals.

Other fishes meet the danger of destruction by
producing enormous masses of eggs. In some these
eggs are poisonous, as in the case of the pike and
the barbel ; in the latter case, in fact, the whole fish
is poisonous at the spawning season. It is often
compared to the pig, as it always remains at spots
where sewage runs into the water. It is even believed
that human corpses are its greatest delicacy ; a large
number of barbel were found on the bodies of the
slain in the Danube in 1683, at the siege of Vienna
by the Turks, while none were seen on the bodies of
animals. Barbel are sometimes taken from the inside
of dead bodies.

Fishes know their enemies well. It has been
observed, in fact, that they have a memory ; that
fishes at which a diving - bird was set first circled
round it with curiosity, but when it had caught several
of them, hid themselves, and were very cautious
afterwards. They also learn to recognise the servant
that brings their food ; but the statement that they
gather for food when the bell rings rests on unsafe
observations. It is very probable that they have no
sense of hearing. Their ear serves only as a sense
of equilibrium ; fishes from which the ears have been
removed cannot keep themselves upright in the water,

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I 77

but answer to sounds in the same way as normal
ones. When fishes come up to be fed, it is because
they detect the steps of the keeper by the shaking
and follow them, or else they see him bringing food.
They have not a great cutaneous sensibility, other-
wise they would not bite over and over again when
they have been let loose by the angler . 1

The fishes have many enemies, but the worst of
them all is man. It is not so much his various ways
of capturing fish that decimate the class as his civilisa-
tion that injures them as it spreads. Sometimes it is
factories that pour their poisonous waste into the
waters, and kill thousands of fishes every year.
Fishes are always very sensitive to bad water. The
tench is the only one that can thrive in water that
is poor in oxygen, and the mud-fish, which foretells
changes of weather twenty-four hours in advance by
its restlessness. This fish can also take air by the
mouth at the surface of the water. The air passes
into the alimentary canal, and is used up there, so

1 According to the latest works of the American expert, Parker, it
seems that there are fishes with a sense of hearing. In the first place,
he says, certain fishes of the order of the “ plectognathi ” (well-known
specimens of these are the trunk-fish and the globe-fish, the prickly,
swollen, globular animals that are often seen in show-cases and dealer’s
shops), must be able to hear, because they make sounds themselves.
Many of them only do this in the male sex, and so the sounds may be
only used within their own species. These are conjectures, but Parker
has proved the sense of hearing with some confidence in the case of
one fish. This is th zfundulns heteroclitus, or toothed carp, an American
fish. The very careful experiments that Parker made with the fish
show that it can hear ; and the same result was obtained on making
an anatomical examination of its ear. It was much more like the ear
of the higher, hearing vertebrates in structure than the usual organ of
equilibrium of other fishes.

M

iy8 DARWINISM AND THE PROBLEMS OF LIFE

that the alimentary canal serves as respiratory organ
in this curious fish . 1

But the regulation of rivers does even more than
factories in reducing the number of fishes ; it deprives
the fishes of their spawning-places just as the cutting
away of the underwood in the forest deprives the bird of
its nesting-place. The regulation of the rivers dams
them up and deepens them, and thus does away with
the shallows and the side-pits. It is just in these places
that most fishes lay their spawn, as it cannot be swept
away, and it receives plenty of sun. The pike likes to
spawn in flooded meadows. The ruffe is the only
exception. It wanders in troops in the spring from its
standing waters into the rivers, until it finds plenty of
reeds, amongst which it lays its eggs.

Many fishes travel in this way. Even the heavy
carp turns up the stream, when it is in free water,
and leaps over high obstacles, in order to lay its spawn
in quiet water near the source of the river. The
minnows travel in swarms to the mountains when the
water becomes too hot for them, and leap over rapids
and weirs. Sturgeons pass from the sea into the rivers
in spring. But the most famous travellers are the eel
and the salmon.

The reproduction of the eel has only been cleared up
very recently. Up to that time the most extraordinary
stories were in circulation about it, as no ova had ever
been found in it. Some maintained that the eels
coupled with snakes ; others that they arose from mud

1 If the animal is taken from the water and squeezed round the
body, the air rushes out with a loud and plaintive noise.

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or putrified bodies of eels ; others that they were
formed from dew and honey. The greatest importance
was always attached to their intestinal worms, which
were claimed to be their young.

We should know that our river-eels are all females ,
and that the males, never more than half a yard long,
live exclusively in the sea or in brackish water. Every
autumn great swarms of female eels, that have passed
their fifth year, travel to the sea, while others remain in
the fresh water, and settle down to their winter sleep
in the mud. The former make steadily down stream ;
never on clear nights, and preferably when a storm
darkens the sky, and the water is lashed by it. When
they reach the sea, the males join them, and the eggs
are laid in the deepest parts of the sea, and fertilised by
the male. The young eels issue from the eggs, but they
are so unlike the old ones that they have always been
described — they have long been known — as a particular
species of fish. 1 They are so completely transparent
that one can read any kind of print through them, and
they are not noticed in the water, as a rule ; in shape
they are flat and lancet-shaped. Gradually, in the
course of a year, they become darker and serpent-
shaped, and then — from May to July — the young
animals travel up stream. They may be seen in count-
less swarms in the under-current of rivers. It is said
that in the year 1667 three million pounds of them were
taken in five hours in the Arno at Pisa. In the Elbe
a black streak has often been seen moving upwards

1 Grassi and Calandruccio have shown that the Leptocephalus
brevirostris is the eel in its early form.

l8o DARWINISM AND THE PROBLEMS OF LIFE

along the shore ; if water was drawn at this time, it
was sure to contain numbers of small eels. As the
large locks now hinder the advance of the young
eels, fish-ladders have been fixed in the wood in most
places — that is to say, bands of moss that remain always
moist, and enable the tiny animals to climb up. The
higher they penetrate, the more the males hang back ;
many believe that the fresh water turns the young,
sexless animals into females, but that has not yet been
proved. The young mature quickly, and feed by
preying on fishes, snails, insects, and carrion ; also on
crabs when they are removing their shells and are still
soft. Eels have often annihilated all the crabs in a
given locality. It is a mere myth, of course, that the
eel goes on pea-fields and feeds on the plants.

The salmon acts in the opposite way from the eel.
It spawns in fresh water. In the sea it lives on small
fishes of all kinds, and becomes very fat. When the
ice disappears from the rivers, the salmon gather at
the mouths in companies of thirty or forty, and remain
for a time in the brackish water, so that the salt-water in
their bodies may be gradually washed out by the fresh ;
too sudden a transition would be fatal to them. They
then press steadily up stream. All obstacles are over-
come. Weirs and rapids are taken in leaps that some-
times reach the height of four yards. Only very high
waterfalls stop them. The young are in front, then the
older females ; these are followed by the younger males,
and the rear is formed of the older males — though an
old and strong fish seems to lead them, as a rule.
During the whole time they are in fresh water the

FISHES

1 8 1

salmon take no food, and the roe — the ova and seed —
mature at the expense of the fat and the muscles. The
old males now develop a bright red colour on the belly,
and at the tip of their lower jaw is formed a strong,
upward-pointing hook ; this is often so long that the
mouth cannot be closed . 1 The swarms separate at the
spawning places, in the streams that flow into the rivers.
In the shallow parts of the streams, especially underneath
small waterfalls, the female brushes aside the pebbles
with her tail, and lies down in the hollow, to deposit her
eggs at the bottom. The male remains about a yard
above, and ejects his seed into the water ; this is con-
veyed by the current to the ova and fertilises them.
When the spawning is over, the two sexes, fearfully
emaciated and exhausted, return to the sea, and
recuperate there. Many of them, however, perish on
the way.

Many salmon pass up river during the spring also ;
they do not spawn, but feed for a whole year as river-
fishes, and do not descend to the sea until the next year
with the comrades they meet in the meantime. They
have the fattest and reddest flesh, and are called winter
salmon. They are the dearest. The salmon going up
stream have also red flesh ; those going down have white
flesh, and are easy to catch on account of their exhaustion,
but are less valuable. The worst fishes are the shore
or black salmon, which never enter fresh water. They
live on the sea-shore and seem to be permanently sterile.
Their flesh is quite white and hard.

Many believe that the hook is used as a weapon in the fight for
the females. The point is not yet settled.

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DARWINISM AND THE PROBLEMS OF LIFE

The regulation of rivers has greatly reduced the
number of salmon. The time has gone when more
than a thousand could be caught at one spot in a day ;
when servants stipulated in their contracts that they
should not have to eat salmon more than twice a week.
In the Rhine it is gradually disappearing, as the mouth
of the river is almost entirely cut off by Dutch fishermen
at the time for coming up. In other rivers there has
been an artificial stimulation for the salmon population.
There are special places in which not only the eggs that
have been found are hatched, but the eggs are obtained
from the body of the ripe female by pressing it (also in
the case of the trout), and the sperm taken from the
male is poured over it. The young ones develop in
vessels full of water, that is kept fresh and circulating,
until they are big enough to make some resistance,
when they are put in the streams. In this way
an artificial substitute is found for the shallow
waters, and thousands of fishes are reared every
year.

For a long time our fresh-water fishes were threatened
with a growing danger of extinction, until at last the
spread of knowledge enabled us to meet most of the
difficulties. Angling societies have been formed, and
fish-culture and protection are spreading more and
more. Angling is still common enough, and is re-
garded as a good form of sport. It is true that we
no longer see boats gliding over the river during the
night with torches in the bow, throwing a red light
over the slender form of the salmon-fisher and his
glistening harpoon ; but the angler sits under the trees

FISHES

183

by the still water absorbed in his work. Lights play
on the water, and the wide straw-hat of the solitary
fisher. The fishes splash here and there, and the
angler waits patiently for the approach of the invisible
inhabitant of the stream.

CHAPTER VI

TRACHEATES

To the tracheates belong spiders and insects. How insects grow.
Explanation of the metamorphoses of insects. Protective
colouring on the wings of butterflies. The Lamarckian principle
refuted by protective colours. Insects that resemble objects.
Mimicry. Exhalation from male butterflies. Sexual selection.
Origin of flowers due to insects. Parts of the insect’s mouth.
Refutation of the Lamarckian principle. The coat of insects
cannot have arisen by use. Harmonious adaptations, co-
adaptations. Co-adaptations that Lamarck cannot explain.
Explanation of co-adaptations. Are instincts inherited habits?
Instincts that can never be affected by the will. Spiders’ webs.
Care of the young. Instincts that are only used once. Are
mutilations inherited ? Protective marks, mildew marks, fore-
sight. Infection of embryo. Structure of the embryo. The
inheritance of acquired characters is difficult to conceive.
Untenability of the Lamarckian principle.

We now turn to the animals that we meet most fre-
quently at every turn. These are all alike in having
the body covered externally with hard parts and jointed,
like the legs of the “articulates,” as we call the stem to
which they belong. Some of these animals breathe by
means of gills ; these are the crustaceans. The others
breathe by means of what are called tracheae ; to this
group belong the spiders and insects, which will engage
our attention in this chapter. The tracheae are a system
of greatly ramified tubes, which end in a network of
very fine microscopic branchlets, and pervade the whole

animal. The air enters into the tracheae by external

184

TRACHEATES

185

openings or spiracles, reaches every organ and every
part of the body, and conveys to them the oxygen that
they vitally need.

There is an immense number of species of the
tracheates. We now know some 250,000 forms of
insects alone, although the tropics, their chief abode,
have only been superficially explored as yet. Such
a number as this is only possible because every avail-
able position in nature is made use of ; and for that
reason we find particularly complicated and striking
adaptations among the insects.

We need only glance at their colours to see full con-
firmation of this. The collector cannot easily discover
a tree-locust on a tree, as it is coloured green like a
leaf ; and its relatives, the grasshoppers, are just as
difficult to find, as their green-brown tint harmonises
with the grass-grown ground on which they sit. The
mole-crickets are quite dark brown ; these are found
chiefly on brown earth, and dig holes, in front of
which they sit and sing their concerts.

We could find an obvious protective colouring in
almost every species of insect. Moreover, the colour
changes at different periods of the insect’s life. The
eggs of most of the insects are green, like the leaf on
which they are deposited. The larvae that issue from
the eggs have a protective colouring, which is different
from that of the adult insect in proportion as their
habits differ from those of the adult. The larva and
the imago , as the full-grown, sexually-ripe insect is
called, often look like two totally different animals.
This is explained in the following way.

1 86 DARWINISM AND THE PROBLEMS OF LIFE

All the articulates, tracheates as well as crustaceans,
can only grow periodically , because they are clothed
with a hard coat of mail. This armour completely
encloses the animal, and the muscles are attached to
it, and find in it the necessary resistance for the pull
on the bones that they effect.

The coat is too rigid and solid to allow any expansion
of the body it encloses. The insect can only increase
in size, therefore, by bursting the shell ; and this it
does at certain places and times. When the armour
is thus broken, the soft - skinned animal creeps out
of it.

Underneath the shell of every insect there is a layer
of skin which has the function of secreting the material
of the coat, much as our salivary glands secrete saliva.
This skin now forms a new shell while the old one still
covers it, so that when the insect emerges from the
broken one, the new coat becomes visible. It is, how-
ever, soft at first, and the insect can expand and grow
in it. But it soon stiffens in the air, and then becomes
a dead mass. Underneath it a new coat is secreted,
and this will replace it in turn when the time comes.

The growth of the insect at each cast is accompanied
by other changes. In many insects the wings make
their appearance ; they were wanting in the larvae,
were visible as short stumps at the first cast, and
increased with each succeeding one until they reached
their full size at the last; in these cases the insect is
thus turned into the imago, or adult and mature
organism. This gradual growth is found in the
dragon-flies, moths, locusts, and others.

TRACHEATES

IS?

As the air is cut off from the larvae it was useful for
them to have different adaptations from the imago.
While the latter flies easily out of reach of its enemies,
the creeping larva can be caught at any time, and so
urgently needed protective colouring so as to escape
notice in its surroundings. Thus the larvae and
imagines were selected in different directions according
to their different conditions of life, and came to differ
more and more.

In the case of moths and grasshoppers, there is not
a very great difference in habits between the larva and
the imago ; the latter hardly use their wings except to
lengthen their leaps. Hence the larva does not differ
so much from the imago, and is merely without the
wings, or has shorter wings.

It is otherwise with beetles, flies, bees, wasps, and
butterflies. The vital activity of these insects chiefly
centres about their power of flying ; some of them
hardly move in any other way. But the air is only
opened to them after the last cast of the skin. The
gradual transition of the larva into the imago would
clearly be very much out of place here, as the two
stages are so very different from each other ; during
such stages of transition the animal would be neither
adapted to its larva - surroundings, which it cannot
leave because of the absence of wings, nor would the
imperfect characteristics of the imago be of any use to
it. We understand, therefore, why natural selection
has cut down these transitional stages as much as
possible, so as merely to let the larvae grow in the
first and most of the other casts, without changing

1 88 DARWINISM AND THE PROBLEMS OF LIFE

their form, which protects them so well. Gradually
only two casts remained for the transformation into the
totally different imago. All the organs of the imago
had to be formed in this short period. But this meant
such a revolution in the animal’s frame that the vital
functions, movement and nutrition, were impossible.
Hence we see that the animal remains, during the
stage between these two casts, in a state of immobility
that may be compared to that of the ovum. We call
this the pupa. In the last cast of skin, the pupa
covering is thrown off, and the wings, which were
formed under it, make their appearance fully developed.

Thus bees, flies, beetles, and butterflies only grow in
the larva stage, as caterpillars or grubs. If we take two
beetles that seem absolutely like each other, and only
differ in size, they are not a younger and an older
animal, but different species.

The material for studying the adaptation of larvae is
inexhaustible. When the butterfly-caterpillars leave the
egg they are generally green, and difficult to distinguish
from the leaf they are on. Identical colour of this kind
can, however, only protect small animals ; larger ones
are sure to attract attention on the grass or the leaves,
because there is no purely green spot large enough to
cover them. As a matter of fact, the caterpillars of
the grass-butterfly (satyridae), when they are of a certain
size, have light and dark longitudinal stripes over their
whole body, and thus lie in the same direction as the
blades of grass and the shadows, which are always
vertical on the grass. The caterpillars of the hawk-
moth, which live on bushes and trees, have stripes

TRACHEATES

189

down the sides, which stand at the same angle to the
length of the body as the side-ribs of a leaf do to the
central rib. This colouring gives great protection to the
caterpillars, as it divides their body into sections just as
the ribs do the leaf.

In the pupa stage, when the insect cannot fly, it is
especially important to have protective colouring; and
it is, as a fact, very common amongst pupae. On the
other hand, a flying insect cannot have protective
colouring because of the constant change of the
animal’s background ; moreover, a flying object is
always easy to see. Hence it is that the upper
surfaces of the wings of many butterflies are of a
light colour, so that the marks for recognising the
species are well in evidence. But the insects are not
always flying ; they often rest, and could then, especi-
ally when they are asleep, be surprised by enemies.
They therefore need a protective colouring, though this
is only necessary at the parts that are seen when the
animal is at rest.

From this we can understand why nocturnal butterflies
(or moths) and diurnal butterflies have protective colour-
ing at different parts of the body. The day-lepidopters
fold their wings over them when they are at rest, so that
we only see the under-side. This alone, therefore, has
a protective colour in their case. We have a striking
example of this in the tortoise-shell butterflies. In the
day peacock’s-eye and the black butterfly the very light
colours of the upper-side of the wings disappear when
they are folded. The dark brown of the under-side
now makes the creatures hardly distinguishable in the

190

DARWINISM AND THE PROBLEMS OF LIFE

dark corners and crevices in which they rest. The
colours of large and small tortoise-shell butterflies and
the painted lady are lighter. They usually sit on the
road, and seem to disappear suddenly after one has
been watching the flying, prettily-coloured insects.

The disposal of the wings is different in the night-
lepidopters. With these the fore-wings cover the hind
ones roof-wise, and so we often find very light colours
on them — as, for instance, in our red underwings or
tiger-moths — and never on the fore-wings, which alone
are visible when they are resting. On these there is
a mixture of different colours, with zigzag streaks and
lines running between them ; the whole taken together
gives so good a picture of the bark of a tree or a
wooden wall that even the experienced naturalist
often overlooks one of these moths in examining the
trunk of a tree. The intricate design is always the
same in every detail, and it has very well been com-
pared to an impressionist landscape, in which all kinds
of scrawls seem to be thrown together irregularly,
though it will be found to be a picture on moving
away from it a little. Natural selection easily explains
a colour-design of this kind. All variations in the
animals are preserved and selected that help on the
resemblance to the bark. In one part the zigzag
lines were developed, in another spots, in a third the
dark ground-colour. As all these selected variations
repeatedly crossed with each other, their descendants
came to possess the different features together , and
steady selection of the combination helped to make
the deception more complete.

TRACHEATES

I 91

While natural selection thus enables us to understand
the origin of protective colouring, we can see no
application in this case of the Lamarckian principle.
The protective colours of animals cannot possibly have
been raised to their present condition by continuous use
and inheritance of the results. In the first place, it is
impossible for an animal to become green because it
takes to sitting on leaves ; and in the second place,
even if the animal knew that it would be an advantage
to be green, it could not change its colour by an effort
of will. It has been stated that the light causes the
colours, and that the animal’s skin photographs the
surroundings, to some extent. It is striking, for
instance, that in many day-butterflies, which draw the
fore-wings between the upward-folded hind wings when
they rest, so that only the tips of the fore-wings can be
seen, these are only protectively coloured like the back
wings just to that extent , while the unseen part of them
is often very lightly coloured. Thus the back wings
and the tips of the front wings have exactly the same
colour-design. And the colouring of the tips of the
front wings is more or less extensive according to the
habit of drawing the wings in more or less thoroughly.
We find this difference in such apparently similar
butterflies as the large and small tortoise-shells. But in
the butterflies that do not draw in their front wings the
whole surface is protectively coloured.

If, however, it seems on superficial inquiry that the
light may have produced the colours, and was only able
to do this on the exposed parts of the wings, we shall
be compelled to abandon the hypothesis on further

I9 2 DARWINISM AND THE PROBLEMS OF LIFE

reflection. We do not see why the light does not
cause light colours such as those hidden in the folded
wings. How, moreover, can we suppose it to create so
intricate a colour-design? And if the skin has the
capacity to bring about a protective colouring, we may
very well ask what was the origin of this capacity, as
very few animals possess it. But we need not delay
with these theories ; they are completely refuted by one
single fact. The protective colouring does not arise
when the animal exposes its wings to the light, but in
the earlier stage of the pupa. Long before it issues
from the pupa all the colours are present on the wings
folded up under the pupa-shell. And in the pupa the
position of the wings is reversed ; the front wings
always cover the hind wings, in such a way that the
protectively coloured under-side of the front wings is
turned away from the light. Hence the light does not
touch any of the protectively-coloured parts during the
development of the colours. We may add that the
thick, dark pupa-covering does not admit the penetration
of the rays of light ; and that many caterpillars pass the
pupa-stage underneath stones, and the night-butterflies
even underground.

We must therefore exclude the action of light
altogether in the formation of the colours of butter-
flies. The fact that their front wings have protective
colouring just in so far as they are visible can easily be
explained by natural selection. We know that selection
only continues its action until what is necessary has
been attained. Those butterflies survived which had
the most deceptive colouring ; but the variations that

TRACHEATES

193

had protective colouring on the unseen parts as well
were no better off than their comrades. They were
therefore not specially selected, and they lost their
shades in their descendants by crossing.

The animal is still safer when its colouring is
associated with certain peculiarities of shape so as to
imitate an object.

The outer side of the wings of the tortoise-shell
butterfly has zigzag lines, so that it looks like a decaying
leaf when at rest. In the lappet-moth there is a most
deceptive resemblance to a heap of dried oak-leaves
owing to the colour and the crinkled edges and position
of the wings. One of our moths, the Xylina vetusta ,
looks just like a broken piece of wood — an effect
which is increased by the creature “shamming death.”
There are also many geometer-moth caterpillars that
closely resemble twigs, and even have warts on their
bodies that look like the unopened buds on the twig.
Further, the animals stretch themselves out stiffly when
at rest, and then rise up at a steep angle from the
branch on which they are, so that they look just like
an offshoot of it.

But the adaptations of insects go a good deal further
than this. They not only imitate lifeless objects, but
even other animals that are not likely to be touched.
Bees and wasps are generally protected by a sting, and
most animals know these weapons and respect their
owners. We must not be surprised to learn, therefore,
that certain harmless insects have the dangerous aspect
of the stinging insects, and so enjoy the same
immunity. A species of fly, the Eristalis , strikingly

N

194

DARWINISM AND THE PROBLEMS OF LIFE

resembles the bee, and the hornet is closely imitated by
the bee hawk-moth, which has assumed the transparent
wings, the shape, and the yellow abdominal bands of
its model. This imitation of living models is called
mimicry, and we find innumerable instances of it in the
tropics . 1

The light colours that many insects show when they
are flying, and that are of great importance to them,
as it is by means of these that the sexes find each
other and maintain the species, are often different in
male and female. In the case of the dragon-flies the

1 The imitation of objects is very common among tropical insects.
There is a leaf-butterfly, the callima, the wings of which, when folded,
not only have the form of a leaf with a stalk, but even a long central
rib with side branches— looks, in fact, so much like a dried leaf that
it takes an expert to recognise the animal at rest. There are also
locusts that have wings most strikingly like leaves, and other locusts
that are almost indistinguishable from twigs ; many naturalists have
thought them to be twigs when the natives brought them.

Mimicry also is wonderfully developed in the tropics. In South
America there are black, yellow, and red butterflies, the heliconides ,
which are not eaten by birds and reptiles on account of their repulsive
smell and taste. Other butterflies, originally white, have adopted both
the appearance and the habits — such as slow flying — of these malodor-
ous butterflies, and constantly mix amongst their models, which always
fly in swarms. Thus the white are protected as well as the heliconides,
though they have not the same nasty taste.

In this case selection has coloured the females earlier and more
thoroughly than the males, some of which still have the pure white of
their ancestors on the hind wing, and some on the upper side of both
the front wings. Selection does not act as powerfully in the males as
in the females, and their transformation is slower. The males are
always more numerous than the females, as a matter of fact, besides
that one of them suffices for the fertilisation of a number of females ;
moreover, their death does not involve the destruction of a number of
eggs. If the species is to be preserved, it is the females especially
that must be cared for.

TRACHEATES

195

female body is usually of a greenish shade, while the
males prefer bluish colours ; in the Libellula depressa
this passes into white, which is the colour of the thick
abdomen in this species. In others the males have
beautiful dark blue wings, which give them a fairy-like
appearance, while those of the females are colourless.
Among the butterflies the argus and small copper butter-
flies have their pretty light colouring only in the male
sex ; the females have an indifferent appearance.

Other “masculine characteristics” are developed
among the insects. In many butterflies the males
give out a strong scent ; it is a charming coincidence
in nature that the butterflies that seem, in form and
colour, to be the flowers of the animal world, have also
very often the perfumes of their models. One can
easily perceive this odour by holding to one’s nose a
male cabbage-butterfly, which differs from the female
by the absence of the black spots and borders on the
wings ; it gives out an agreeable pungent odour. The
argus butterflies, the mother-of-pearl, the convolvulus-
sphinx, and many others, have a male scent. In all
cases the odour is restricted to special scales. The dust
of the butterflies, which is so easily brushed off "with
the hand, consists of very delicate and tiny scales, which
are for the most part connected with small glands.
Some especially large glands secrete an odorous matter,
and let it pass into a peculiarly shaped scale which is
called a scent-scale. These scales are often closed by
special structures, so that they only pour out their
perfume at the will of their owner. It appears, therefore,
that in this case the perfume is really meant for the

196 DARWINISM AND THE PROBLEMS OF LIFE

enchantment of the females, and we are faced again
with a problem that we cannot solve. In this case
there is less objection than elsewhere to the second
form of sexual selection. It is not called upon to
explain the origin of the perfumes, but only its increase
in the male sex. The odour certainly came into
existence as a distinctive mark of the species, as it is
also found in the female sex, though in so weak a
form that our nose cannot perceive it. But it can
easily be proved to be present by placing a female of
some species of night- butterfly in a wire box before
the window. A number of males will presently be
found in it, and they can only have discovered by
smell the presence of the object of their desire.
Hence if a female knows the odour as a mark of the
species, it will be much more affected by it when
its strength increases. Possibly this is the root of its
advancement.

The union of the sexes is sometimes stormy among
the insects. The females of the large dragon-flies often
fly in obvious fear from their spouses. In the case of
other insects it is the male that must be careful. It
happens only too often that the love-sick male cricket
is devoured by the callous female. In fact, in the case
of the mantis or praying insect, a green locust whose
front legs are lifted up as if in prayer, though they are
really only for the purpose of grasping its prey, the male
is generally devoured during , but at least always after,
union. It has even been observed in the case of this
species that the female bit the head off the timidly
approaching male ; the trunk, nevertheless, performed

TRACHEATES

197

its task, and was then in turn taken into the stomach of
the insatiable female. In the case of the spiders, too,
the male must approach the female with caution as she
sits in the middle of her web, because she has a habit of
biting to death without much examination every living
thins: that comes into her net. But in this case the
female signifies its compliance to the hesitating male.
She travels down, and hangs, head downward, by a
thread on which the union takes place.

We have already compared the butterflies to flowers.
That was merely a superficial comparison, but we shall
now see that there is an intimate connection between
insects and flowers, because, strange as it may sound,
most flowers owe their origin to insects.

We must go back a little in order to explain this
statement. In the plants, also, a union of male and
female generative products is necessary to produce a
new organism. The male products, which correspond
to the sperm of the animal, are called “pollen”; it
consists of an immense number of very tiny grains.
The pollen of the lily must be known to everyone, as
it is this that colours the finger yellow when you insert
it in the flower. This pollen has to unite with the
female product, which in turn may be compared to the
ovules of animals. The plant “ egg,” which is found also
in flowers, but only in small quantities, is in this case
enclosed in a capsule that is called the “ seed-bud ” or
germ, and is drawn out in a long stalk called the “ pistil ”
above. At its upmost point, the “stigma,” a grain of
pollen touches it in fertilisation, passes gradually through

I9§ DARWINISM AND THE PROBLEMS OF LIFE

the pistil to the egg-, and coalesces with it. Then, as a
rule, the germ drops off, tumbles to the ground, and the
fertilised egg within it grows into a new plant. In
ordinary usage we call the fallen germ the “seed.”

In the parent-forms of the actual higher plants there
were male and female blooms, and the pollen was pro-
duced by the former in vast quantities and scattered far
and wide by the wind. In this way a grain would fall
on the stigma of a female plant and it would be fertilised.
This is still done in the case of a great many plants,
such as the grasses, the conifers, the birch, the hop, and
many others. The male blooms were constantly visited
by insects, as the pollen was an excellent food for them,
and this visit of the insects became the starting-point
for natural selection which made the conveyance of the
pollen to the female flowers safer, instead of leaving it
to the chances of the wind.

Fertilisation was easier in those plants which offered
some attraction to the insects, as after visiting the male
flowers there were always a few pollen-grains sticking to
their body, and when an insect in this condition entered
the corresponding female flower, it was natural for some
of the grains to be brushed on to the stigma. We can
understand, therefore, why little pits came to be formed
in the female blooms of many plants, in which a sweet
fluid was secreted that attracted the insects. The
willows have remained at this stage, but in their case the
male flowers also secrete honey, and thus it is secured
that both kinds of catkins will be visited by the insects
and fertilisation obtained.

However, this form of conveying the pollen left a

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good deal to be desired. It would often happen, for
instance, that an insect would fly from one male flower
to another, and not visit a female catkin until much
later. In this way a great deal of pollen would be
lost, and so we can understand that a different method
would lead to better results. We still find in the
poplars, which have the same kind of catkin-blooms,
a pistil with a stigma and germ suddenly appearing
as an abnormality in the middle of a male flower ; this
union of male and female in one flower is called
hermaphrodism. These hermaphrodites were pre-
served by natural selection, as they had a great
advantage in the conveyance of pollen from flower
to flower. An insect that covered itself with pollen
dust in one flower found a pistil in the next one on
which it could brush the dust, and did not fail by going
exclusively from one male flower to another. Hence
the hermaphroditic flowers increased, and a struggle
sprang up amongst them for the visitors, those being
most favoured that were most attractive to the insects.
The chief means was, of course, the honey on which
the insects fed ; and those flowers had an additional
advantage that drew attention by their conspicuous
colours, and so invited the insects from afar. This
was the origin of almost all our actual beautifully-
coloured and marvellously-shaped flowers. Nature does
not revel in a superfluous wealth of colouring ; this has
only been developed for the sake of the insects, as no
plant of this kind can reproduce unless it is visited by
insects. A second source of attraction was provided
in the scent, which, of course, was especially useful

200

DARWINISM AND THE PROBLEMS OF LIFE

during the night. In fact, many plants that are only
visited by hawk-moths only give out their perfume at
night when these moths fly. Many will have already
seen this in the case of the caprifoliacese.

At first sight it would look as if those flowers were in
the best position in which the honey was most exposed,
and which were visited by as many insects as possible.
But that is not the case. In the first place, many insects
are so small that they can eat the honey without rubbing
against the pollen, and so they are useless to the flowers ;
and in the second place, the flower will have a much
better chance of being fertilised if only a few species of
insects visit it. When a certain kind of flower is liked
by a particular insect, this will be the more likely to
return to it, and not waste its pollen on other flowers.
On this account the honey that was at one time exposed
in many flowers has sunk deeper into them, and thus
can only be reached by the more intelligent insects.
The effect is enhanced by the curling of their leaves so
as to form a tube which varies in thickness, and so
admits different kinds of insects. In some flowers the
tube is so narrow that it takes the long proboscis of a
butterfly to reach the honey. Others have adapted
themselves to flies, and give out the smell of carrion,
which attracts these alone. In the aristolochia the long
and narrow tube is further provided with hairs on all
sides that point downwards ; these let the fly in, but
prevent it from escaping. The insect is kept captive
until it is covered with dust by the stigma at the
bottom, when the hairs wither, and it can get away.
In this way the restless fly is compelled to do its duty.

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It would take too long to enumerate all the
adaptations of the flowers to insects. The most familiar
of all is the meadow-sage. In this the bees in search of
honey press on a small mechanism by means of which
the filaments, at the tip of which the pollen hangs, bend
down on it and dust their hairs with it. The bee then
leaves the flower, and another comes which has already
been covered with pollen in this way. But in the mean-
time the pistil with the stigma, which had up to that time
been hidden, has come to the opening. The second bee
has to rub its body against the stigma in order to reach
the honey, and so cause fertilisation.

We thus see that the origin of the flowers affords a
striking proof of the power of natural selection, and this
will be particularly clear if we consider the relative
imperfectness of the adaptations. Selection only acts
in so far as a change is urgently necessary for the
preservation of a species. Many flowers can only be
fertilised by bees, but they also receive the visits of
many other insects which rob them of their honey with-
out doing them any service. However, it is clear that
further contrivances for excluding these other insects are
not necessary, because the maintenance of the species is
sufficiently assured by the bees, whose visits are frequent
enough to fertilise and bring new plants into existence.

The alteration of the flowers was bound to have an
influence on the insects. When those of the flowers
were constantly preserved that had the longest tubes,
because they kept out mischievous visitors and so were
most frequently fertilised and left most progeny, there
must have been a corresponding selection among the

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DARWINISM AND THE PROBLEMS OF LIFE

insects ; the butterflies with the largest probosces would
have the advantage because they would find most food,
and their ova and seed would be the most vigorous.
Thus the characters would mutually affect each other.

It is not only the proboscis of the butterfly, but also
the mouth-parts of other insects, that have been modified
by a correlative selection with the calices of flowers. In
the ancient insects the eating organs consisted of mas-
ticators, as we still find in many orders, such as the
locusts, moths, and beetles, because they chew their
food. But in the bees a part of the mouth was converted
into a long licking tongue ; and in the butterflies two
masticators have blended to form the long tube of the
proboscis.

In other insects there have been different modifica-
tions of the mouth-parts. The masticators of the gnats
have been converted into long stilettoes. The larvae of
the dragon-flies, which live in the water, have developed
the lower parts of the mouth as pincers, with a long
retractile stalk, and able to seize an animal at some
distance when they are suddenly thrust out. We
should never come to a stop if we were to examine
all the adaptations of the mouth-parts of insects. We
will desist, however, and briefly consider the other parts
of the insect body.

The wings have entirely disappeared in the flea ; in
the fly the back pair has degenerated, and in the
strepsitera 1 the front pair. In the earwig the wings

i The strepsitera, to which belongs, for instance, the “Stylops
melittse,” have some peculiar adaptations. The larvae, which jump
briskly on their six legs, force their way into the bellies of bees and

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203

are folded together, and can only be opened with the
aid of forceps at the extremity of the abdomen. In
the beetles, only the hind wings are used for flight ;
the front wings form a cover for them. There is
equally endless variety in the legs of insects. In the
mole-cricket the front extremities have been converted
into shovels ; in the grasshoppers they have become
a powerful leaping apparatus.

The skeleton of the articulates, with all these peculi-
arities, is of the greatest theoretical value. It provides
ample material for the refutation of the Lamarckian
principle, as it is Weismann’s merit to have shown.
We saw above the way in which insects grow. Under-
neath the shell the skin secretes a new one, but this
is soft and elastic, and only hardens when the old one
has been cast off. All the characteristics of the coat —
its thickness, its different kinds of hairs and other out-
growths — are already formed before the old coat is cast
off. When this is done, the new one appears in full
development ; it hardens and grows no further, as our
bones do, because it is an excretory product of the
underlying skin. As soon as the shell comes to light,
the skin which has produced it loses its connection with
it ; it has to begin immediately the work of secreting
a new coat.

wasps, though not deeply, and become pupae there. From the pupae
issue the insects that have become males, and fly away with their large
bird wings. The females do not leave the pupa-covering ; they are
without wings or legs, and like grubs, and remain in their wasp until
a male comes to fertilise them. The larvae develop from the fertilised
ova in the mother’s body, and then break out of the mother’s back,
and in their turn make their way into wasps.

204 DARWINISM AND THE PROBLEMS OF LIFE

These peculiarities of the coat cannot be explained
by the Lamarckian principle. We will not speak of
the hairs and protuberances, as to which it is quite
unintelligible how such structures, which only act when
they are formed and have never been used, can be
strengthened by exercise. But let us take a simple
case. The Lamarckians would explain in the following
way the hard inner edge of the crab’s pincers, which
grow in the above manner. The shell of the pincers
was thin at first. The crab then formed the habit of
seizing its prey with the pincers, and using them as a
weapon. By the continuous pressure of the claw-fingers
on the inner side in bringing them together, the shell
gradually hardened at the edges, in much the same way
as the fingers of seamstresses or violinists develop a
harder skin by pressure. Once the inner edge of the
crab’s claws had become thicker by this continuous use,
and it came to have young ones, these would have a
thicker shell at the part in question from birth, owing
to heredity, and it would be increased in the course of
generations until the actual claws were formed.

The comparison with the skin of the finger seems to
be helpful, but we have really to deal here with two
totally different facts. The human skin is alive, and the
living substance can certainly be strengthened by use,
as the muscles of the athlete’s arm show. But the
crab’s shell is dead ; and dead structures do not become
better, but, if anything, worse by use. They get used
up, like a steel spring that has been long in use.

When the coat was still connected with the living-
skin, when it was still in the process of being formed

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205

from the skin by secretion, it could not be altered by
use, because it was the old, overlying shell that was
then in use. The characteristics of the articulate
skeleton cannot, therefore, have been developed by use,
as in each case they were fully developed before use.
When a crab casts its old coat, it appears in the new
one, which is still soft, but soon sets. But the soft
shell has all the protuberances and thick parts, and does
not differ in the least in structure from the hard one.
Moreover, it would not help even if the soft shell could
be modified by use. The soft crab refrains from using
his soft claws, with which he could do nothing. He
creeps under a stone and waits idly until the coat is firm
enough to protect him.

To this view it has been replied as follows. The
shell may not be able to thicken from pressure, but the
skin that is forming the new coat underneath it may.
Pressure in the old shell affects the underlying skin as
well, and its function, the secretion of a new shell, will
be proportionately stimulated, and produce it in a
thicker condition. Hence when the crab continually
uses its claws and so presses on the inner side of them,
this pressure will act through the shell on the skin
beneath it ; this will do more work, and at the next cast
of the coat the inner edge of the claws will be thicker.

But why should the skin act more and not less
vigorously under pressure ? It is not at all agreed that
it secretes a thicker and not a thinner coat, when it is
pressed through the overlying shell. And even if we
admit that its activity is increased by pressure, how
did this capacity come into existence ?

206 DARWINISM AND THE PROBLEMS OF LIFE

However, we need not linger with these objections to
the theory. There are certain facts that completely
demolish it. These facts are the casting of the skin
of beetles, flies, wasps and butterflies. In all these
animals the coat of the imago is formed underneath
the pupa-cover. The legs are pressed against the
body, the wings folded, and everything enclosed by
the pupa-skin as in a parcel. But the pupa scarcely
moves , and so there can be no pressure to act through
its shell on the underlying imago skin. And even if a
pupa happened to be exposed to pressure, the stimulus
would act equally on all parts of it, as in the pupa
they are all folded together, though in the adult insect
they must be wide apart and differ very much in thick-
ness, as they do in point of fact. Finally, it is precisely
the thin parts of the imago coat that lie directly under-
neath the pupa skin ; many of the thick parts are
protected from pressure by the overlying wings.

It is clear, therefore, that in the secretion of the
imago coat the skin cannot possibly be influenced by
pressure. Nor even immediately after the emergence of
the insect. The imagines of the insects enumerated
may expose their coat to all kinds of pressure, as much
as they will, the underlying skin will never be caused
thereby to secrete a stronger coat, because in these
insects it has no further activity in the imago. No
butterfly ever casts its skin ; this is done by it several
times as a caterpillar, and once as a pupa. None of
the characteristics of the coat of a bee, the wing-
nervures, the thick and thin parts, the various kinds
of hairs, the eye-facets — none of these things can

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20 7

have arisen by use and the inheritance of its results.
The whole coat, with all these prominences, is a
dead structure ; it can only be worn out by use, as it
has no living parts to replace or increase what has been
used up. The animals retain this shell until they die ;
no new one is formed underneath it, and there is no
coat-producing skin there to be influenced by pressure
or use. Hence the peculiarities of the imago coat of
these insects cannot possibly be explained by the
Lamarckian principle.

But they are explained by natural selection. Every
living thing varies, and so there will be a slightly
different imago formed under the pupa-cover of each
separate insect. When the animals issue forth, their
variations come to light, and are selected or rejected
according as they are useful or otherwise. They will
either be preserved and accentuated by continuous
selection, or they will disappear. And as the

Lamarckian principle cannot possibly have formed
the details of the coat of these insects, but natural
selection may have done so, we have a right to assume
that the shell of the Crustacea and of the insects with
gradual growth was not brought about by the “ inheri-
tance of functional modifications,” but by a process of
selection.

There are certain adaptations which many experts
think cannot be explained by natural selection, but only
by the Lamarckian principle. These are what are
known as “harmonious adaptations” or co-adaptations.

There were in former ages stags with antlers six and
a half yards high. The animals could, of course, only

208 DARWINISM AND THE PROBLEMS OF LIFE

support these heavy antlers on their heads if they had
skulls of proportionate thickness and necks strong
enough to sustain the ponderous head. Even the
animals’ shoulders and other parts of the body must
have been powerfully developed. We see, then, that
strong antlers involved a whole series of co-adaptations ;
that is to say, it was not enough for variations with
larger antlers to appear among the stags, but in these
very cases there would have to be also a number of
other organs modified in a definite direction. But this
could not be expected in variations. They depend on
chance ; each varies on its own account, and there is
no hand guiding them from some higher standpoint.
If one amongst a litter of stags has larger antlers, it is
possible that it may also chance to have a stronger
collar, but some of the other parts will certainly be
found to be weaker ; it is too much to expect from
chance that so many organs should vary in the same
direction. The reader will be able to follow the
argument best by imagining a game with twenty dice.
The different numbers that come out on top will
represent the variations arising at each throw —
corresponding to each litter of young. As it is
demanded in the case of the stag that some animals
shall appear with, let us say, ten definite variations, we
must require that ten of our dice will throw the number
six. Certainly one of the dice, possibly two, will throw
a six after several attempts, but it is improbable in the
highest degree that ten dice will give that number,
however often they may be thrown.

The Lamarckian principle meets the difficulty.

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209

When from any cause the antlers of the stag became
larger, they exercised a pressure on the skull, which led
to its thickening, and the other parts of the body would
be equally strengthened and modified by the pull of their
burden. These variations were transmitted to offspring,
and if a still stronger pair of antlers arose in the next
generation, and was selected, it found better support, and
would in turn improve this by its pressure, and so
the advance would gradually continue.

This kind of explanation seems simple enough, but

there are certain co - adaptations that it cannot cover.

This is the case with the insects once more. We have

already seen that the cutaneous skeleton of these

animals is dead, and can only be used up, not

strengthened, by exercise. Now, the peculiar fiddling

apparatus of the field-cricket only makes its appearance

at the last cast of the skin. It consists of two very

different parts — a bow, which is represented by a

specially modified nervure of the wing, and the side

across which it is drawn. The latter is a part of the

inner surface of the hind leg, which is equipped with a

number of little teeth ; it is these that give out the

chirping sound when they are rubbed. Here we have

a co-adaptation that the Lamarckian principle cannot

explain. Two organs that lie in different parts of the

body are modified in the same direction, so that one

can only co-operate with the other ; but they can neither

have arisen nor been improved by use. They only

make their appearance at the last cast of the skin, and

when they rub together they only wear themselves,

since they are dead structures, and the underlying

o

2 10

DARWINISM AND THE PROBLEMS OF LIFE

skin cannot be stimulated by the pressure to form
stronger parts, since its function ceased at the last
cast of the skin.

In the same way we find many other co-adaptations
in the coats of bees, wasps, butterflies, etc., in which
the last cast is the abandonment of the pupa-skin, when
they first receive their specific features, such as wings
and so on. Hence when we find on the fore-legs of
bees and wasps certain structures consisting of two
parts forming a ring with teeth in its inner side, through
which the antennae are drawn to be cleaned, we have a
structure that cannot have arisen by use. The same
may be said of the mouth-parts of these insects. In
the gnat there are at least eight parts that are all
modified in the same sense as stabbing - bristles and
suctorial apparatus ; they are all about the same length,
and can only act in conjunction. The antlers of the
large stag with the thick skull and the proportionately
modified other parts are not more wonderful than the
parallel development of the mouth-parts of the gnat.
When the Lamarckian principle is admitted on the
crround that it is said to meet difficulties that natural
selection cannot explain, we see that this is not the case.
At all events, it does not do away with the difficulty of
co-adaptations, because there are co-adaptations that it
cannot explain.

But are co-adaptations really inexplicable by natural
selection ? Selectionists say they are not, and they
are quite right. In the first place, artificial selection
shows that harmonious variations do actually take place.
Think of the dachshund, which has been brought to its

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2 1 r

present form by a continuous selection of the shortest-
legged pups. In its variations there were always
corresponding modifications of the other organs, such
as, broader paws, thicker legs, and changes in the
bony structure and length of the body. The latter
feature is absolutely necessary to secure mobility in a
low animal, as we see in the case of all short-legged
or legless animals, like the marten, the lizard, or the
serpent. Just as, in the selection of the dachshund,
all the corresponding variations appeared quite spon-
taneously, without the vital activity of the developing
variety being drawn upon, that might also happen in
the parallel case of natural selection, and therefore in
the selection of the giant antlers of our stag. We must
not forget, moreover, that an organism is a harmonious
whole, in which continuous selection has brought about
an ever improving co-adaptation and co-operation of
the various parts. Hence, when the variation of a
longer bone occurs in a leg, the corresponding muscles,
blood-vessels, and nerves are also usually longer. It
has even been discovered that when fly-maggots are
kept without food, the flies that issue from them are
smaller than usual, but have a complete harmony of the
various organs. Selection has led to this harmony, and
it preserves and increases it ; every organism that lacks
it will be crushed out as a cripple. Moreover, natural
selection can often develop similar organs in different
directions. We see this in the legs of the leaping
mammals, in which the hind legs are much longer than
the front.

Further, co-adaptations may often be brought about.

2 12 DARWINISM AND THE PROBLEMS OF LIFE

by combination. It is clear that natural selection may
attain the same end by different means. When, for
instance, the herons began to seek their food at the
bottom of the water, selection favoured not only those
with long legs, but also those with long bills and long
necks. The end was reached by all three modifications,
and so they were equally selected. The continual
crossing of the three characters gave rise to the actual
herons, which have all three of them.

Finally, we need not suppose that the co-adaptations
must arise simultaneously , and it is precisely in this that
the chief difficulty was found. Remember our illustra-
tion from the dice. We can easily get our ten sixes if
we throw until a six turns up, then leave this standing,
and throw again until another six appears, and so on
until we have got our ten sixes.

Natural selection may act in the same way. In the
giant stag first large antlers were favoured ; they were,
of course, not immediately so heavy that the animals
with weaker skull and neck were incapacitated, because
all variations are small at first. When a race of stags
with large antlers had thus been formed, and continued
to increase, the time came when only the individuals
with strong skulls could carry the antlers with ease.
Then the thicker skulls were selected. Thus all the
co-adaptations might be selected successively ; even if
they were wanting at first, they were bound to appear
in the course of a long period, and would then be
favoured. But even if they were wanting at first,
the animals with the larger antlers were not necessarily
incapacitated. We must not forget that use in the

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213

course of an individual life certainly strengthens an
organ, though the result of it is not, in my opinion,
inherited. As the antlers of a stag need years to grow,
and their weight does not increase so very much in
each year, the head and neck will become stronger
under their increasing burden, so that an old sixteen-
pointer can bear a considerable weight. However,
this strengthening by use can only advance to a certain
point, as we see in the old illustration of the man who
carried a calf every day and so was able to lift it even
when it had grown into an ox. The man could never
have lifted two oxen, even if he had begun with two
calves. Hence there came a time in the development
of the giant stag when the antlers were so heavy as to
interfere with the mobility of the animals ; then the
animals were selected which had a stronger constitution
from birth.

Hence, as the co-adaptations do not need to appear
simultaneously, but may be selected successively during
long periods, they present no difficulty to natural
selection. The Lamarckian principle is not only
inapplicable to a number of co-adaptations, but it
is wholly unnecessary for explaining harmonious
adaptations . 1

1 Weismann further instances the many co-adaptations of the ant
and bee-workers, whose frame cannot have been formed by the
inheritance of the effects of use, because the workers inherit nothing t
since they do not reproduce at all. The queens, which give birth to
the workers along with the rest, have a totally different structure.
Weismann explains the case by a selection of stocks. Those stocks were
always preserved, the workers of which took most care of the eggs and
the stock. At the same time those queens were selected which were not
only the best queens, but also brought the best workers into the world.

214 DARWINISM AND THE PROBLEMS OF LIFE

There is still one province in which the Lamarckists
think their principle is indispensable ; this is the province
of instincts. It is said that we cannot understand these
except as inherited habits.

We saw above that instincts are Grounded on com-

O

plicated reflex actions. It is just as difficult, moreover,
to put limits between instincts and voluntary actions as
it is between reflex actions and instincts. It is certain
that actions which were at first voluntary and have
often been repeated become at last instinctive. There
is the pianist, for instance, who practises a piece
consciously and with an effort of will. In the end
he will play the piece quite instinctively, often while he
is thinking of other things altogether. With many
people it is entirely instinctive to take out their watch at
night, or to clean their teeth — in fact, to perform a large
number of actions which were at first controlled by the
will. That voluntary actions may become instinctive by
frequent repetition is as certain as that organs become
stronger by exercise.

Hugo von Buttel-Reepen, the leading authority on bees, has shown
at length how we may conceive the origin of the bee-state by selection.
At first there were a few living females, which laid their eggs in
sheltered hollows and provided them with food, as many wasps still do.
Then those females were selected that remained with the eggs and
watched them until the young issued. The next point was that the
first females to come from the eggs took a part in the watching of the
rest of the eggs and larvse. After this there was a more and more
complete division of labour, in virtue of which the older female was
turned exclusively into an egg-laying machine, and the others worked
for the community. The great advantage of the state is that, even if
numbers of the feeders of the swarm are destroyed, there is always a
sufficient number left to supply its needs. The limits of the present
work unfortunately forbid me to enlarge further on this interesting
subject.

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It has been claimed that voluntary actions of this
kind that have become instinctive, or habits such as
these, may be inherited. That, however, is not found
to be the case with the pianist ; his son must learn the
art himself laboriously. It is the same with reading
and writing.

Thus we see from the start that all voluntary
actions that have become instinctive are not inherited.
It is true, say the Lamarckians, that all habits are not
transmitted, but the instincts we find in the animal
world are inherited actions that have passed from
voluntary to instinctive. There are instincts so wonder-
ful that we can only conceive them as impulses perfected
by intelligence, which have reached their present height
by the inheritance of such usage during a long series of
generations.

But when we examine the impulses of animals, we
find that in a large number of them this conception
is quite impossible. There are instincts which it is
impossible to imagine as having ever been initiated by
the will of the animal, or having been improved by use.
This is clear in the course of one of the most original
impulses — that of flying from enemies.

When a fly darts away from the hand that tries to
capture it, this is certainly not a voluntary act that has
become a habit by practice and been transmitted as such
to posterity. It can hardly be supposed that the fly
knows what it is to be killed. Nor can it ever learn by
experience how swiftly it must fly, as every insect that
does not get away promptly loses its life. Finally, the
action is clearly seen to be unintelligent from the fact

216 DARWINISM AND THE PROBLEMS OF LIFE

that the fly constantly returns to the same spot, although
it has barely escaped frorm the hand of the catcher
a number of times. The fly is certainly not an
intelligent animal, otherwise it would know that the
spot was dangerous. Clearly, in its flight we have an
instinct that causes the animal to fly away quickly, by a
sort of reflex action, when a body approaches it rapidly ;
an instinct that was not initiated by intelligence, nor
practised.

We must equally discard the Lamarckian principle
as an explanatory factor in dealing with the instincts
that accompany protective colouring. The murderous
mantis, which is of a green colour like the surrounding
grass, steals very slowly on its prey. The xylina , that
looks like a piece of wood, shams death ; that is to say,
remains quite motionless, and finds excellent protection
in this way. Can these animals know that their
colour is only useful to them if they act in accordance
with it ?

Butterflies that are not eaten on account of a nauseous
taste or smell are distinguished, as we saw, by glaring
colours. They fly slowly, because it is best for them
to be seen clearly, so as to be recognised from afar as
inedible before a bird can seize them. No one, surely,
will suppose that these animals are conscious of the
advantage they have in flying slowly.

There are, nevertheless, intelligent tracheates whose
instincts might seem to have been originally acts of
intelligence, which they have improved by reflection,
and have transmitted the results to offspring. I refer,
especially, to the spiders.

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217

When a garden -spider is preparing its web, it first
climbs to a high point, gives out two threads from its
spinning glands and attaches them. It then lets itself
down by the two, either to a branch that lies right
below it or in a slightly oblique direction ; it accom-
plishes the latter movement by swinging itself about.
One of the two threads is again attached and drawn
tight ; the other is bitten off, and is carried by the wind
until it reaches a branch that lies on a level with the
upper point. The spider crawls up it, draws it tight,
and attaches it. It then lets itself down and prepares
the second vertical thread. It furnishes the horizontal
thread either in the way we have described or by
making a circuit, passing from one point to the other
on the ground, spinning its thread all the time and
drawing in the long thread with its fore - legs and
fastening it. When it has thus prepared the frame of
the net, it runs to the centre of the horizontal thread,
and lets itself down vertically to the lower one, and thus
forms the diameter-line. Then come the radii from the
centre ; these are fastened to all the required points,
when the spider has reached them by means of the
existing threads. Last of all the concentric lines are
made by passing from one radial line to another. The
whole web is often made in a single night.

The work of the house-spider is simpler. It draws
threads backwards and forwards across a corner, and
lurks in the tube it has spun. Very remarkable, again,
is the conduct of the large water-spider. It breathes
the air, although it lives in the water, and has in the
hairy coat that clothes its abdomen a means of retaining

218 DARWINISM AND THE PROBLEMS OF LIFE

air underneath the water ; this gives it a bright silvery
appearance. The water-spider makes underneath the
water a diving-bell as large as a wall-nut, bringing
down in succession from the surface the air-vesicles it
has wound round. It usually lives in these bells, and
stores its prey there.

If it were said that intelligence prompted the spider
to modify its web in this way, and practice had made
it perfect, the claim would not apply to the bell that
the water-spider constructs for its young, which is
closed below as well. The spider cannot possibly know
that the eggs and the young that issue from them need
air. But if the one web has been produced without
intelligence and practice, it may very well be the same
with the other.

We are, in fact, compelled to exclude the influence
of intelligence in this care of the young by the
tracheates, because the parents only make the shelter
for them, and never see their offspring, and so cannot
know their needs. The black water-beetle spins two
plates, lays its eggs inside, and weaves the edges to-
gether. It thus forms a raft, one side of which is drawn
up in the shape of a little horn, so that it always floats
with this uppermost. Still more complicated is the case
of the predatory wasps. These powerful creatures fall on
an insect, probably a caterpillar, paralyse it by a sting,
and drag it into their nests, where they lay the spoil
in a cell, deposit an egg on it, and cover up the cell.
The larva develops from the ovum, and feeds on the
victim, which has been prevented from decaying by
being merely paralysed. Sometimes, indeed, the egg

TRACHEATES

2 19

is suspended over the victim by a thread, so that the
convulsive movements of the caterpillar may not injure
the larva, which can always retreat by the thread.
Here again we must discard the supposition that the
wasp executes all these details because it knows what
will be good for the larva. And the instinct cannot
have been perfected by practice, because they lay very
few eggs in the course of their life.

There are, moreover, plenty of instincts that only
act once in the lifetime. In these cases it is frequently
clear that the Lamarckian principle entirely fails, because
here there is no practice whatever and consequent
improvement.

An insect only passes into the pupa stage once in
the course of life, so that this act and the preparations
for it have not been practised. But these preparations
are amongst the most wonderful and most complex
instincts. The matter is comparatively simple in many
of the day butterflies, such as the common white ones.
These, while in the caterpillar stage, spin a thread
round themselves, and hang down by it from a wall.
The thread must be just as long as the thickness of
the pupa, otherwise it may either be pressed or fall
out. How can the caterpillar know how thick it will
be in the pupa stage ? And how can it practise spinning
its thread when it only does this once in life ?

The larva of the large stag-beetle passes into the
pupa stage in a hollow ball of clay prepared by itself
with polished walls. In the insect that will become
the male this is much longer, because of the large
antler-shaped jaws, than in the case of the future females,

2 20 DARWINISM AND THE PROBLEMS OF LIFE

whose tentacles are small. Here the constructive
instinct differs for the two sexes. But in neither case
can we suppose that the larva knows what sort of
tentacles ft will have. The clay-ball, moreover, is only
formed once in life, and there is no possibility of
practice.

One of the most complicated pupa-coverings is the
web of the small nocturnal peacock’s eye. In this case
there is a hole for creeping out in the spun capsule, but
in order that the enemies of the pupa may not crawl
in by it a bundle of stiff silk-bristles, with points directed
outwards, is spun over the hole, and acts as a weel.
The bristles are easily pushed aside by the butterfly
when it issues forth, but they prevent an entrance from
without. Here, again, there can be no question of
practice, as the caterpillar only makes the web once
in its life, and makes it — must make it — correctly on
this single occasion. The intelligence of the caterpillar,
moreover, has certainly nothing to do with the work,
as it cannot know that it will need special protection
during the pupa stage, and that this complicated
structure on its home will keep off its enemies.

We see, therefore, that the Lamarckian principle
entirely fails to explain many instincts. There are
instincts that can never have been acts of will and
intelligence, and others in which the element is entirely
wanting to make them instinctive even if they had
once been voluntary actions — namely, practice or
repetition — as they are only performed once during
life . 1 If the complex instincts we have described cannot

1 Instincts of this kind are Weismann’s chief objection to Lamarckism.

TRACHEATES

22 I

have been brought about on Lamarckian principles, we
must discard them in the case of all instincts.

But we have already seen, in the second chapter,
that instincts present no difficulty to natural selection.
Instincts vary, just as the parts of the animal body
do, and so can be selected and improved. They are
adaptations, and are often only of use in the circum-
stances in which their possessors ttsually live ; they are,
therefore, relatively imperfect, as we should be bound
to expect in view of their origin by selection. A
cricket that saves itself in nature by digging swiftly
into the ground repeats the movement even on hard
gravel or on a glass plate, when it would do better to
run away. A bee stings a human being, whose skin
closes over the wound, and retains the sting with its
barb, which is fatal to the bee. Its sting is only
provided against its chief enemies, the insects, whose
coat remains open after the wound is inflicted, and lets
the sting out again. The imperfectness of these
instincts tells very clearly of their origin by natural
selection.

Hence, though many scientists retain the Lamarckian
principle because a number of the characteristics of
animals seem to them inexplicable without it, we have
seen that these characteristics are also found in circum-
stances where the Lamarckian principle cannot be
admitted at all. We found this in the case of the
skeleton of insects and their co-adaptation. We now
find it also in their instincts.

The Lamarckians, however, retain their theory ex-
clusively, though they know it cannot be proved. How

222

DARWINISM AND THE PROBLEMS OF LIFE

often it used to be said that mutilations were inherited,
yet all the alleged proofs of it have been found invalid !
There is not a single case in which a pup has been born
with its tail cut off, or an individual born, amongst the
Semitic races that practise circumcision, with that
particular mutilation, though it has been practised by
them for thousands of years. It has been found just
as impossible to prove a case of a change that had
occurred in an animal’s lifetime being transmitted to
its young. We sometimes read in sporting papers that
red spots have been found on the young in the womb
of a deer at the spot where the ball struck the mother.
That would be a very sudden inheritance of acquired
characters ! Many people still believe that pregnant
mothers can influence their offspring by fear, that the
child will have burn-marks if the mother has seen a bio

o

flame before birth ; it is quite arbitrary to call the red
spots burn-marks, instead of blood-marks, or anything
else. It is also thought that crippled limbs from a fall
can be inherited.

These beliefs have not been sustained by scientific
inquiry. The many cases that have been investigated
by experts have generally been explained in the sense
that the feature in question was already in the family as
a congenital characteristic. Not a single case has been
established scientifically in which an acquired character,
a mutilation or a habit, to which there was not a
predisposition, was transmitted to children.

It is, of course, a different matter with infection and
poisoning. These affect the germ ; they taint the
whole body, and do not leave the ova and sperm

TRACIIEATES

223

untouched. But in these cases the germ is not modified
in a particular direction, but is diseased , like the whole
body. This is what we have in cases of syphilis or
alcoholic poisoning. The infection of the germ is
brouo-ht about either by minute organisms that pene-
trate to it, or by alcohol, which naturally reaches the
germ as it courses through the whole body.

The Lamarckian principle cannot, therefore, help us
in explaining certain characteristics of animals, because
it does not explain many of them ; in the second place,
it cannot be proved ; and in the third place, it is not an
explanation at all.

Natural selection rests on two causes, both of which
have been demonstrated — on the variations of animals
and their inheritance, and on over-production and the
destruction of a certain percentage which this entails.
But of the two postulates of the Lamarckian principle
only one has been established, and this only in certain
cases. This is the statement that an organ is strengthened
by use and enfeebled by disuse. The second postulate
— that these changes affect the germ in precisely the
same sense — is a hypothesis that has not only never
been proved, but itself requires explanation.

We must certainly admit that the ova — and also the
sperm — that mature within an animal are infinitely com-
plicated structures ; and that in each ovum there is an
enormous number of minute particles, each of which
forms a certain organ when an animal develops from the
ovum. But these particles are not miniatures of the
subsequent organ ; they have a totally different form.

Hence the stimulus that modifies any organ of the

224 DARWINISM AND THE PROBLEMS OF LIFE

mother must penetrate to the ovum, must make its way
through all the particles, without affecting them, and
must influence precisely that particle which will form the
same organ in any child that may develop from the
ovum. But as the particles have quite a different form
from the organ in question, the stimulus, when it has
reached its object, must suddenly transform itself in a
mysterious fashion, much as electricity is converted into
sound in the telephone.

Let us take the case of a woman strengthening the
muscles of her arm by bending and stretching it. Even if
this stimulus penetrates as far as the ovum, there is no
arm there for it to strengthen in the same way, there
is merely a minute point that will form the muscle later
on, but at the time has nothing muscular about it. The
stimulus must, therefore, transform itself in order to
influence this point so as to produce a stronger arm
subsequently than it was originally calculated to do.

By what means, moreover, will such a stimulus be
conveyed ? By the nerves ? By the blood ? These
can at the most only convey a fuller or thinner supply
of nourishment to the ovum. How, then, can they be
the means of influencing just one particle, and that in
a q7ialitative sense ? When a woman, for instance,
injures her eyes by too much sewing, the most that can
be done is for the particle which will form the eye of
her child to receive a worse supply of nourishment.
But why should that make the child’s eye short-sighted,
instead of smaller ?

There are other hypotheses as to the conveyance of
the stimuli that affect the body to the ovum, but they

TRACHEATES

225

are all grounded on precarious conjectures, not on facts.
Hence the chief postulate of the Lamarckian principle
itself requires explanation. Then there are the
numerous categories of facts in which the principle
entirely fails. There are so many characters of animals
that have never been exercised because they only act
when they are already there — such as colouring. How
could any conceivable exercise of the salivary glands
bring about the poisonous character of many serpents ?
Use can at the most cause the glands to secrete a
larger quantity , but not a different product ? And how
could the spines of the hedgehog arise from its being
often bitten in the skin by its enemies ? The thorns
that protect plants from being eaten are also just as
impossible to explain as due to use.

We must, in fact, be very careful with the word use
or exercise. We often read in Lamarckian literature
that pressure will in one case lead to a less development
of the parts pressed, and in another case to a stronger
development . 1 The first postulate of the theory is
therefore unsafe in many cases. It lends itself far too
much to being used as a mere phrase that explains
nothing. This organ must have been strengthened by
exercise, they say, knowing neither if it was in reality
much used, nor if exercise would modify it in the

1 Thus in Plate’s works pressure generally has a strengthening effect,
but in the case of the hermit-crab, the abdomen of which is buried in
a snail-shell, the steady pressure is regarded as having a weakening
effect and leading to the disappearance of its coat at this part. In
general, however, Plate makes a moderate and judicious use of the
Lamarckian principle. Pie recognises its weak points, but thinks it
is necessary for the explanation of certain phenomena.

2 26 DARWINISM AND THE PROBLEMS OF LIFE

particular direction. And when the same stimulus is
said to weaken in one case and strengthen in another,
we shall do best to discard an explanation that is
unworthy of the name.

It might still be said : We admit that the chief
postulate of the Lamarckian principle has never been
proved, but that is because we know so little about the
conveyance of stimuli in the body. Still, the principle
has one advantage. It unites a large number of cases
under a single head. Thus we trace all the cases of
falling to terrestrial magnetism without knowing its real
nature.

But it is precisely the element which gives any value
to such a concentration — the embracing of all falls that
we observe under one law — that is lacking in the
Lamarckian principle, which always leaves gaps that
it cannot explain. And apart from the fact that the
principle cannot explain the origin and transformation
of the organic world as a whole, it proves useless even
in small groups of cases, and it has to leave gaps in
those where its action seems most probable, such as the
co-adaptations.

There is only one phenomenon in the organic world of
which selection does not give an entirely satisfactory
explanation. I mean the rudimentary organs. But
even here the Lamarckian principle is of no use to us,
as it cannot have acted in many of these cases, and so
we know that rudimentary organs may be brought about
without its aid. There are some in the coat of insects ;
I need only recall the degenerated wings of the orgyia,
which consist mainly of shell. In this case the inactivity

TRACHEATES

22 7

ought to preserve rather than injure the wings, since
dead structures are all the better for being spared, as
anyone can see in the matter of his clothes. Hence,
the wings ought to have been used up and atrophied
precisely in the case of the flying insects, and have been
preserved in the case of the non-flying, such as the orgyia.
There are many rudimentary organs in the coat of
insects. To these the Lamarckian principle is inappli-
cable, and so once more we must discard it as unsafe and
only explaining a part of the instances.

To conclude ; no case has ever been known of the
inheritance of the effects of use and disuse, and so the
Lamarckian principle has not a single established fact
to support it. Its possible sphere of action is very
limited ; even amongst a given class of phenomena it
has always to leave inexplicable gaps. There is an
enormous number of instances to which it has no
application. Of the two postulates on which it is based,
the first is only certain in a few cases, and at the most
merely possible in the majority. The second postulate
is not an established fact, but a pure theory ; a theory,
moreover, that is difficult to imagine, and in its turn
postulates all sorts of phenomena and relations of most
of which nothing is known. Finally, the Lamarckian
principle is an obstacle in the way of a unified conception
of things, such as it is the chief aim of the theory of
evolution to build up, and can never be reconciled with
it. We shall see more of this in the eleventh chapter.

But I think we have now said enough to deprive the
Lamarckian principle of all power to modify the forms of
the organic world.

CHAPTER VII

CRUSTACEA AND MOLLUSCS

Economy of nature. The chemical constituents of bodies. Chemical
combinations. The elements. The albuminoids. Biogens as
constituents of living matter. Vital phenomena and apparent
death. Metabolism. Structure of the living substance. Plants the
foundation of life. Order of sustenance in nature. Flesh-eating
is more natural to the animal than plant-diet. Are all variations
useful to animals ? Value of selection. Origin of the shells of
snails. Change of functions. Development of the crab. Why the
embryonic development of an animal reproduces its racial history.
Reconstruction of embryogenesis. Uncertainty of the biogenetic
law. Parthenogenesis, the development of unfertilised eggs.
Significance of the germ-cells. Significance of sexual reproduction.
Amphimixis. Plural variations.

In every pond there are living at a certain depth
innumerable tiny creatures up to the size of a pin’s head.
They pass up and down unceasingly, and travel back-
wards and forwards through the water. Every hour
swarms of them are devoured by their countless enemies,
yet we see no sign whatever of a diminution of their
numbers. The heat of summer broods over the pond,
the vapour rises to the clouds, aquatic plants come to the
surface and wither in the heat ; in a short time there is,
instead of the pond, a dry earth-pit covered with animal
remains. In the autumn the rain sets in, the ground is
moistened, little pools are formed, and soon the rich

colours of autumn are reflected on the surface of the

228

CRUSTACEA AND MOLLUSCS

229

pond. The little creatures have returned as if by
magic, and fill the water once more. Other aquatic
animals were unable to sustain the drought, but they are
there again as soon as the water covers the bottom ;
the interval seems to have had no effect on their life.

These minute animals, which fill the ponds and
seas in such numbers that every cast with a fine net
brings up a mass of their bodies from the bottom, are
called water-fleas. They belong to the gill-breathing
articulates, the Crustacea. They have a shell, and
grow by casting the skin, like all other articulates.

The small crustaceans play an important part in the
life of a pond, as most of the fishes and a good many
other animals could not exist without them. These
build up their frames with the flesh of the little
crustaceans. The water-fleas form a tooth in the great
cog-wheel of the earth’s round. It turns on and on;
substances are formed from stone and water ; from these
is built up the living matter that appears first of all in
the tiniest organisms ; from these are made larger and
larger animals which will decay in turn, until the turn of
the wheel is complete, and the stone and water are there
once more to provide material for the fresh start.

In order to understand better this “economy of
nature,” we must begin a little further back.

We know that the mass of the earth, with all the
rocks, the water, and the air that surrounds our planets,
consists of elements , of which more than seventy are
known. These can combine in so many different ways
as to produce the immense variety of forms of matter
that we see every day. Such elements are, for instance,

23O DARWINISM AND THE PROBLEMS OF LIFE

oxygen, hydrogen, nitrogen, carbon, all the metals,
sulphur, phosphorus, and others.

These elements may unite in two different ways to
make up the materials we find in nature — in simple
viixtures or in chemical combinations.

A mixture can easily be understood. We may take a
piece of copper, for instance, file it down, and mix it up
thoroughly with ground sulphur so as to form a greyish-
green powder. This seems to be quite homogeneous,
but we find that it is not if we examine it under the
microscope. If we apply a higher power, we see clearly
that the new powder consists of grains of sulphur and
copper, lying side by side.

But if we heat the mixture until it becomes incan-
descent, and then let it cool, we get a black substance
in which we cannot detect, under the most powerful
microscope, a single grain of sulphur or copper. A new
body has been formed, and this cannot at once be
separated into its constituents, as the mixture could be.
The new body has also different properties from its
constituents ; they have, as we say, entered into a
chemical combination. In the present instance the
compound is called sulphuret of copper.

There are vast numbers of these chemical compounds
in nature. Water is one, for instance ; it consists of
hydrogen and oxygen. On the other hand, the
elements that form the chemical compounds are rarely
found in a free state in nature. Iron, for example, is
never found pure, but always combined with sulphur in
sulphuret of iron or other forms.

It is possible to break up chemical compounds into

CRUSTACEA AND MOLLUSCS

23I

their constituents by a method that we call “analysis.”
But this analysis can only continue until we reach the
elements. It is the characteristic of these that, however
much you subdivide them, the particles are always of
the same kind. They consist of a single form of matter.
Take gold, for instance; however small it is ground up
or chemically divided, it remains gold.

We have now analysed all the substances on the
earth, including the substance of which living things are
composed. It has been found that the living substance
contains just the same elements that we find in the
lifeless crust of the earth, in the inorganic world, as we
say. It is true that only a few of the elements — twelve
in number — are found in living matter ; these are,
especially, carbon, hydrogen, sulphur, nitrogen, and
oxygen. But while the elements of organisms are the
same as those of the inorganic world, they enter into
different compounds in living things from those we find
anywhere else. Of these compounds it is especially the
albuminoids that distinguish the living substance and are
never absent from it. They are very elaborate com-
pounds ; we have succeeded in analysing them, but
not in building them up from their known elements,
because we do not know the arrangement of these,
nor the forces and concomitant circumstances in which
the elements enter into an albuminous combination —
in the way that we found heat uniting sulphur and
copper into sulphuret of copper.

Thus there is no difference in principle between the
composition of living and lifeless matter. Nor is there
any essential difference between the forces at work in

232

DARWINISM AND THE PROBLEMS OF LIFE

each substance. The only difference is that we always
find in the organic world certain very complex chemical
compounds, especially the albuminoids, that are not
found in the inorganic.

But important as the results of long chemical research
are, we must not exaggerate them. The living sub-
stance is as enigmatic as ever, because we only know
its composition after death. The analyses that have
acquainted us with its constituents had to kill it before
any result could be obtained. We may, nevertheless,
assume that the organic substance consists chiefly of
albuminoids in life as well as after death, but their
behaviour is very different in the two cases. We can
preserve dead albumen for a long time, if we keep
bacteria away from it, without decomposition setting
in, whereas the albuminous matters in the living
state are continually breaking up even under normal
conditions, and the more readily the stronger the
stimuli that act on them. We must, therefore,
draw a profound distinction between living and dead
albumen.

This has induced many scientists to discard the name
“ living albumen,” and replace by the term “ biogen.”
We know very little of the real composition of these
biogens. As they pass into dead albumen when the
organism dies, it is very probable that they closely
resemble it in texture, and especially that they contain
no different elements. But certainly the grouping of
their elements is different from in dead albumen ; it
is, in particular, looser, as only in that way can we
explain the ready disintegration of the biogens. It is

CRUSTACEA AND MOLLUSCS

233

precisely in this looser texture that we find the centre
of gravity of the whole life.

The living substance has distinctive properties which
we call the phenomena of life , and which are familiar
enough to everyone as nutrition, movement, irritability,
and so on. When these properties disappear we say
that the organism is dead.

All the vital phenomena, however varied they may
be, are based on one property of the living matter,
namely, its interchange or circulation. The funda-
mental quality in this is “ metabolism ” ; that is to say,
the living substance breaks up of itself unceasingly and
regenerates itself, and in doing so thrusts out matter
from itself and takes in new matter from without. As
- it is the living albuminoids that behave in this way, we
may say : Life consists in the metabolism of the biogens.

This metabolism ceases when life has left the body.
We have, in fact, every reason to believe that the
metabolism is suspended in “sham death,” even when
it is voluntary, as in the case of the Indian fakirs.
The trance or simulated death of the fakir may last
for six weeks. Many of the animals, also, fall every
year into an apparent death-condition, and awake to
new life in proper conditions. The seeds of plants
may lie for years without vital functions, yet germinate
when they are put in moist earth. The very finest
methods have failed to detect any trace of giving-off
matter in these seeds. But it is untrue that the
grains of wheat taken from Egyptian tombs thousands
of years old grow into plants. They decay when they
are put in water.

234 DARWINISM AND THE PROBLEMS OF LIFE

The constant renewal of the disintegrating biogens
is effected, therefore, by the taking-in of matter. This
must, of course, contain the elements of which the
living substance is composed. These elements, we
know, are found in inorganic nature. Thus the
organism is like a laboratory, in which chemical com-
pounds are constantly set up and taken to pieces again.
The requisite elements are taken from the earth, the
water, and the air. These are first of all united in
simple combination in the organism, and from these
more complex ones are formed, and so the activity
of the living substance goes on until the albuminoids
are produced. The albuminoids are converted into
living albumen, or biogens, by rearrangement of their
constituents. Here the highest point is reached. The
series of changes then descends once more. The living
albumen becomes dead, this disintegrates, more and more
simple compounds appear, and in the end combinations
of the simplest nature.

But, we may now ask, who represents the chemist in
this living laboratory, the man who chooses and brings
together the requisite substances ?

The new biogens are formed from the old. The
dead albumen that is imported into the body is con-
verted into living by the biogens. When these have
created new biogens, they break up, but owing to
their activity before death the body loses none of its
living albumen.

However, the conversion of dead into living albumen
is only the last part of the work done in the body.
Who selects the matter that is to be taken into the

CRUSTACEA AND MOLLUSCS

235

body out of the number of substances found in nature,
and who converts them into dead albumen by
progressive combinations ?

First of all, we must explain that the forces that can
do this are only present in the plants. These alone
have the power to select the requisite elements for
making albuminoids out of water, air, and earth ;
animals have lost this power. The latter must always
obtain their albumen ready made, and their biogens
will then convert it into living albumen. Animals
perish if only supplied with inorganic matter, as their
biogens then find no albumen that they can convert
into particles like themselves. They cannot make a
beginning with inorganic material, as their substance
has not the power to put it through the long series
of combinations that are necessary for the production
of an albuminoid.

Thus the whole animal world is based on the plants.
These alone have retained the power to form living
matter out of inorganic substances ; they are now the
sole laboratory in which albuminoid substances are
prepared. This can be done, however, only by the
green plants ; the others, such as the fungi, need organic
nourishment, like animals. The green in the plant
consists of microscopically small granules of chlorophyll ;
they have the power, under the influence of sunlight,
of gradually creating organic matter from the necessary
elements of the air, earth, and water. The plants are
the foundation of life. They alone can cover the steady
return of living substance into inorganic matter, during
its disintegration, by re-forming organic from the

236 DARWINISM AND THE PROBLEMS OF LIFE

inorganic. They thus exercise their power, not solely
for themselves, but also for the whole animal kingdom.
The animals can only cover their loss of organic sub-
stance from disintegration by obtaining albuminoids
ready made, which they merely convert into living
matter. They either take their food from the plants,
or they satisfy their need of organic food by devouring
their fellows, and these must have built up their frames
on vegetal matter. The groundwork of all life is found
in the plants ; without them the animal world is
unthinkable.

Let us now consider a world in miniature, a pond, in
order to see the successive steps in the provision of
food. There must first of all be plants, if any living
substance is to be formed at all. In the pond these are
chiefly algae, tiny green vesicles, which often swim freely
about. These algae form the food of the water-fleas,
the crustaceans of which we spoke at the beginning of
this chapter. Most of the other animals live on these
fleas, as also do the fishes, which feed almost exclusively
on water-fleas in their earlier stages. The fleas are,
therefore, an important connecting link in the economy
of Nature.

Even from this instance we see that it is not the
higher plants that form the groundwork of the nutritive
scale. This will easily be understood from the fact that
the higher plants are very complex structures, with their
stem and roots, leaves and flowers ; they must have
been developed at a late date, when there were already
plenty of animals. Thus the first “ angiosperms ” — or
all our foliage-trees and shrubs, and many of our herbs

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237

— only appeared about the Tertiary period, and so come
after many groups of vertebrates, such as the reptiles,
had reached their greatest height. In fact, the whole
intricate mechanism of the plants — the leaves, flowers,
etc. — only came as an adaptation to life on land ; marine
plants have remained at the primitive stage of seaweeds
and algae.

The plant-eaters are, of course, older than the flesh-
eaters, since the first animals can only have had organic
food in the shape of plants. But we must not generalise
too much on the strength of this fact. Once the world
was filled with the tiniest animals, the higher animals
could be developed from them, and grow and advance
at their expense. It has been rightly pointed out that
animal food comes more naturally to the animal than
plant-food. Every animal has been accustomed to an
animal diet in its earlier period, whether this consisted
of the yolk of an egg or the milk of the mother. The
break from this early diet to plant-food with its hard
substance, the cellulose, is very considerable, and we
can understand why the higher plants have been
avoided and the earlier vegetal diet retained.

The chief difficulty in following the food-series occurs
in connection with the land-animals. In the sea there
are lower algae that are eaten by the smallest animals,
and these in turn are devoured by the larger. Here
nearly all are carnivores ; vegetarians are very rare
amongst the larger salt-water animals. We can thus
see that these tiny, lowly algae provide the organic
matter for the whole animal life of the sea, since this
is prepared from inorganic substances by the algae

2 38 DARWINISM AND THE PROBLEMS OF LIFE

alone ; it then passes through the whole series of
animals until it reaches the great monsters of the
deep.

It is otherwise on the land. Here there are none of
the lower algae and the minute animals that we call the
protozoa. We have, therefore, to construct a different
diet-series.

It is clear that all the higher characteristics that the
plants developed on land first put in their appearance as
root, stalk, leaves, and fibres, without being devoured
by the animals. The leaves were not used as food
until some time afterwards. It is probable that at first
the land-plants only served as food for the animals after
they had decayed, and so been modified by bacteria.
The earthworms, which are certainly ancient species of
animals, still feed in this way. Other animals may have
lived directly on the fungi, which were certainly nearer
to the diet they had been accustomed to from their early
days than the green plants. The fungi have a similar
composition and nutritive value to the animals. They
have no green colouring matter, but feed on organic
matter that the green plants have made.

There is only a step from the eating of decayed
plants to the eating of carrion, and this comes close to
flesh-eating. We can best understand the flesh-eating
animals if we assume this to have been the development
of their diet. We are speaking, of course, only of the
original animals ; in the higher ones the food changes
according to the adaptation. Thus our former state-
ment, that a flesh diet comes more naturally to an
animal than a vegetal diet, is not inconsistent with the

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239

ruminants. Natural selection can certainly cause the
adult animal to adopt a diet different from that it was
accustomed to in its youth.

We have a good illustration of such a development
of diet in the second great group of animals with which
we have to deal in this chapter, the “molluscs.” The
chief representatives of this stem amongst us are mussels
and snails. Of the latter, the land-covered snails eat
fungi or mould, and the road-snails fungi. But a few
species in each family have taken to a flesh diet. They
can, of course, only catch slow animals such as earth-
worms or other snails. And it is only certain species
of snails that they eat, while avoiding the rest, possibly
because they are protected by a strong slimy secretion.

The mucus is a general characteristic of the snails.
Our water-snails use it for creeping on the surface,
many experts believe, and as a fact this seems to be
the simplest explanation of the mysterious progress of
the pond-snail on the surface of the water, with its
body bent downwards. The snails which seem to
have the flat part hanging in the air, and to creep on
this, give out a long slimy thread and glide along this.

The water-snails have a peculiar organ that enables
them to rise or sink without effort, as the fishes do.
This is their breathing organ, a cavity in the body that
opens externally by an orifice. The animal sinks by
compressing the cavity, and rises again by dilating it.

The respiratory cavity is the lung of our molluscs, and
is found both in the land and water-snails, as the latter
are land-animals that have passed into the water, and
must come to the surface to breathe and close the cavity

24O DARWINISM AND THE PROBLEMS OF LIFE

below. However, the ancestral forms of the snails are
in the sea, and are gill-breathers. How were the lungs
formed when they came to live on land ? The organ
for breathing air could not be large enough from the
start to perform its function. How was it possible,
then, for variations which represented the rudiment of
an organ that could not yet act, and so were useless , to
be preserved and favoured by selection ?

Here we have what is considered to be the radical
objection to the theory of selection ? The action of
natural selection is made possible by the variations that
bring about differences between animals, and cause some
of them to be retained and others extinguished on the
ground of their better or worse qualities. But these
variations are insignificant in themselves. Hence if an
animal only differs very little from its fellows, we can
hardly say that it has on that account more chance of
surviving or perishing than they.

Let us take an instance. In the craw-fish the eyes
are fixed on mobile stalks, and so the animal, the whole
fore part of the body of which is rigid, is able to see over
a larger area. In its ancestors the eyes were set deep
in the head, as is still the case with the centipedes and
the smaller crabs. According to our theory, those
crustaceans must have been selected whose eyes stood
out a little higher than those of their fellows, so that
they were favoured in the struggle for life. But, it may
be asked, could this trifling elevation of the eyes really
be such an advantage to its possessor ? The field of
vision would only be the smallest degree larger than in
the other crabs. If individuals arose amongst those

CRUSTACEA AND MOLLUSCS

24I

early crabs that had eyes already projecting on small
stalks, we should acknowledge that these had an
advantage, as they would perceive their enemies or
their food quicker than the others. In a word, the
changes that any organ or character of an animal shows
at birth must generally be so slight that they can have
no selective value ; that is to say, their owners cannot
be so much better situated on account of them as to
escape the destruction that falls on their fellows.

Above all, it is said, we cannot see how complex
organs and instincts can have a selective value from the
beginning. The trunk is indispensable to the elephant.
It uses it as a weapon, conveys food to its mouth with
it, and cannot lift objects from the ground, or drink,
without it ; these are all actions that it could not perform
without the trunk on account of its short and stiff neck.
But the trunk is only useful at its actual length. If the
ancestors of the elephant had noses of ordinary length,
like the tapirs, they would hardly be able to perform one
of the above functions, and they would not have any
advantage in variations that added a small fraction of an
inch to them. We cannot admit, therefore, that the
first slight lengthening of the nose was so useful that
the elephants which did not possess it were the first to
perish. In other words, we do not see that these nasal
variations would have any selective value.

However, let us take an instance from amongst our
own animals. Take the shell of the snails. This is
certainly useful to the animals, as they can withdraw
into it and find shelter from their enemies and from bad

weather. But the shell did not appear at its full size all

Q

242 DARWINISM AND THE PROBLEMS OF LIFE

at once ; it must have been small at first, so that the
animal could not retire into it. Thus the shell was of no
use at first, and so the snails in which it first made its
appearance could not have been favoured by natural
selection.

Nevertheless, the origin of the snail’s shell by natural
selection is not so unintelligible at all. It has been said
that the ancestors of the snails were animals that
migrated from the depths of the sea into the surge-zone.
These were at first devoid of shells, and clung to the
rocks with their foot. The force of the surge must
have destroyed numbers of them, tearing the animals
from the rocks and dashing them against the stones.
Those had an advantage, therefore, which had some
feature that modified the force of the surging masses of
water. This was a slimy layer that made the back of the
animal smooth, so as to give no point of resistance to the
water. All snails do, as a matter of fact, secrete this
slime, and we can conceive this faculty to be increased
by selection. But selection altered the quality, as well
as increased the quantity, of the secretion. It was useful
for this to become thicker and thicker, and thus at last
the shell was formed, covering the snail like a shield.
Each small variation was useful from the first, as we
saw, and as the variations affected the whole dorsal
surface of the body they led in time to the formation of
a structure covering the entire animal. When the snail
took to further migration and to the land, other
variations would be selected until the snails’ house was
formed, however small it may have been.

We must be careful in urging the objection that many

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243

organs could not have had a selective value from the
first. Even such complicated structures as the wings of
birds and insects could arise gradually, as we saw in the
fourth chapter, and were clearly useful from the start.
Further, it has been rightly pointed out that sudden
crises may occur in animals after periods of rest.
During these the utmost demands are made on the bodily
and mental constitution of the animals in the general
devastation, as the stronger often fall upon the weaker
members of the same species. Large numbers of
animals perish in a severe winter, and we may assume
that even a slight variation in the thickness of the fur or
the feathers may save an animal from destruction. It
has also been said with truth that in the migratory birds,
for instance, slight advantages in the power of flight
may do much, as the effects accumulate in the course of
the long journey. Cyclists know that if they are to win
a race every small part of their machine must be as light
as possible.

It is often difficult to imagine how an organ can have
arisen by natural selection, yet we detect a means on
further reflection. The origin of the wings and
of the snail’s shell seemed for a long time to be a
hopeless enigma, but the solution was at length dis-
covered. If we can find the answer to these really
difficult questions, we may hope to do the same for the
remaining problems in connection with the evolution of
animals or organs. But above all we must not at once
throw the blame on the theory of selection when we
cannot find the solution, but must remember the
imperfect condition of our knowledge. We cannot

244 DARWINISM AND THE PROBLEMS OF LIFE

determine the origin of any organ with certainty , as we
have no absolutely certain documents. We construct
the development of animals and their organs with the
highest probability, once we have established the fact
that they must have been evolved. The soundness of
the theory of selection is by no means shaken by
quoting organs the origin of which we are not at
present able to explain.

We will not attempt at the moment to settle com-
pletely the difficulty that arises about the selective
value of variations. We will merely refer to a
subsidiary principle which provides a simple solution
of the difficulties that are found in regard to the
usefulness of the first variations of many organs. This
is the principle of change of function.

We became acquainted with this principle in describ-
ing the conversion of the swimming-bladder of the fish
into the lungs of the amphibia. Something similar
happened in the development of the land-snails. In
the marine snails the gills lay in a cavity that opened
externally, and there were several blood-vessels in the
wall of it. In the pulmonary snails also the respiratory
organ is a cavity which differs from the preceding one
chiefly in the absence of gills, and in the fact that the
blood-vessels in its lining are so numerous and ramified
that the air can give its oxygen, which penetrates through
their thin walls, to the blood. These lungs are one of the
best conceivable instances of the gradual transformation
of one organ into another. They show, in the first
place, that here, where natural selection needed an
extensive organ from the first, there was one ready to

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245

meet the requirement ; and in the second place, it is
clear that here the smallest variations had selective
value, because as they passed on to the land every
advance in the ramification of the blood-vessels in the
lining of the cavity meant a richer supply of oxygen,
and secured a longer life.

There are plenty of examples of organs that had at
first a certain function, and were enabled from their
constitution to take up a secondary one. If a change
took place in the habits of the animal, this second
function might become the principal one ; in fact, the
first might gradually disappear, and the organ would
be correspondingly modified. We have a process of
this kind in the limbs of the craw-fish. It has feet on
what is called its tail, as well as the five pairs of legs,
of which the first bear the claws. The animal’s tail
is really its abdomen, and must not be compared to the
tail of the vertebrate ; the alimentary canal runs through
it. The legs on this abdomen were at first clearly for
swimming, but were also used by the female for
carrying the eggs. The second function became more
important when the animal took to crawling as its chief
method of locomotion, and so the abdominal legs
became smaller and smaller by selection, and are now
only useful for carrying the eggs ; even in the male
they are used in connection with reproduction.

Other legs of the craw-fish have undergone an even
greater transformation. All the limbs of the Crustacea
were originally legs, even the feelers, or antennae, that
act as organs of smell or touch, and the masticating
apparatus. Most of the masticating organs look very

246 DARWINISM AND THE PROBLEMS OF LIFE

much like feet, except that the first masticators are shaped
like two strong teeth. But, it will be asked, how do we
know that these and the antennae were originally legs,
when they have no resemblance to legs ?

The answer to the question is given by embryology.
In the case of a good many Crustacea the ovum produces
an animal that is very different from the adult, and is
known as a nauplius- larva. It is unarticulated, and has
a simple organisation and only three pairs of legs, with
which it swims about with a kind of hop. The larva
gradually grows ; its hind end lengthens and breaks
into joints, on which new limbs sprout out ; these differ
in number according to the number possessed by the
adult of the particular species. But the original three
pairs of limbs of the nauplius are converted into the
two pairs of antennae and the first masticators. These
have therefore been developed from legs, as we clearly
see.

There are crustaceans that have become parasites ;
they cling to other animals, and feed on their vital
fluids. These have changed their form so completely
that they may be taken for a piece of the intestine or
at all events a worm, but never for a crustacean. The
most curious, perhaps, is the sacculina , a crustacean that
settles on the abdomen of a marine crab and is shaped
like a sac ; widely branching root-fibres proceed from
this and penetrate the whole interior of the crab and
suck its blood. Yet this organism, so little like an
animal, is a crustacean ; in its youth it has the form
of one, and it emerges from the egg as a nauplius that
cannot be distinguished from the nauplii of other

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247

crustaceans. In fresh water, also, there are crustaceans
that have assumed the most curious shapes owing to
parasitism, such as the Achtheres percarum, a parasite
of the perch.

The Crustacea are particularly striking illustrations of
the biogenetic law that we mentioned in the fifth chapter.
The crustacean reproduces in its ontogeny — its develop-
ment from the ovum — the course of its phylogeny, or
ancestral development in past ages.

In the above-mentioned parasites we can understand
why they cannot give up the free-living stage of their
ancestors in their development. How could they reach
their host — how could the animal, for instance, that
comes from the sacculina egg reach its crab, if it could
not swim freely about at the beginning of its career, and
then settle like a plant on its victim ?

There are only a few animals in which it was
necessary to retain the ancestral stages. In many
cases it will be an advantage to the animal to be as
fully developed as possible when it leaves the egg, so
as to reach sexual maturity quickly and provide off-
spring. The whole development has, therefore, to take
place in the egg, as is the case with the birds, and
individuals of this kind are protected by the shell of
the egg or within the mother’s womb. But a develop-
ment of the animal within the egg implies a certain size
in the egg, because, whilst the free-swimming larva can
obtain from without the necessary nourishment for its
growth, the animal in the egg is restricted to the supply
of food inside the shell, or to the substance that we
call the yolk. Eggs with much yolk can, in view of

248 DARWINISM AND THE PROBLEMS OF LIFE

their size, only be produced in small quantities ; but on
the other hand, the amount of nourishment provided
enables the young in them to run through the stages
of development more quickly than the free larvae, which
have to struggle laboriously for the matter with which
to build up their frames.

When an animal is brought by natural selection to
develop in the egg instead of as a free larva, a number
of changes will follow. All the characters that can only
be of use to a free-living larva are cut out in the
embryonic development as so much waste of time and
material, and only those ancestral stages will be retained
that are necessary for the further development of the
specific marks of the animal. Here we come to the
essence of the biogenetic law. It is not a law of
absolute and universal validity, like the law of gravity,
otherwise every animal would have to reproduce exactly
in its embryonic development the stages of its ancestry,
which is not the case. It is no more than a postulate
of the action of natural selection. All the characters of
animals must arise in connection with others already
existing ; nothing can be developed suddenly and
without intermediate stages. Hence if a new organ has
been formed from a previous one by gradual modifica-
tion, it must follow the same line in its development
from the ovum to the adult, because the ontogeny also
can only proceed gradually. Thus the biogenetic law
demands that just as an animal could only develop
further in its ancestral history on the strength of
qualities already existing in its predecessors, so in its
individual growth it must build gradually on the actual.

CRUSTACEA AND MOLLUSCS

249

And this is, in the present case also, the succession of
ancestral stages.

When an adult animal is modified by natural selection,
this modification will be the last to appear in the
development of its descendants. It is always the
terminal stages of animals that are vitally affected by
selection. But the further the modification of the new
species proceeds, the more will the embryonic develop-
ment be affected. The organs that assume an increasing
importance and range in the transformation will no
longer find time for their development in the final
embryonic stages, and their formation will be pushed
further and further back, since those animals will always
have the advantage in which the organ is formed first,
and so most completely developed. Thus the most
important organ in man is the brain. This enormously
complicated structure naturally requires a very long time
for its construction, and so we can understand why it
should be one of the first organs to appear in the
embryonic development, and why in the human embryo
its size is altogether out of proportion to the small body.
But it is utterly wrong to conclude from this that the
human embryo with its large head and small body
must prove according to the biogenetic law that man’s
ancestors were similarly misshapen.

In the transformation of species many new organs
become larger and more important than the old ones,
and these will accordingly, if they continue to be
necessary but can be quickly developed, only be formed
at the close of the embryonic life. This in itself will so
modify the individual development that it will be almost

25O DARWINISM AND THE PROBLEMS OF LIFE

impossible to gather the ancestral history from it.
But the effect will increase if many of the organs of the
ancestors are no longer necessary, and are not found in
the adult animal. It is true that these will still have
to appear in a rudimentary fashion in the embryonic
course, but those animals will be steadily selected in
which they take a shorter time and are less in size, as
they then leave more room to the other organs. In the
end they will be forced out of the embryonic develop-
ment altogether. This must, of course, take place
gradually, and if we find the gill-clefts of a fish still
appearing, and then disappearing, in the human embryo,
it only proves that the time when our ancestors had the
fish form is not yet very remote, from the geological
point of view . 1

Finally, natural selection will modify the ontogeny by
means of new structures arising. Thus in many ova
and larvae special contrivances have been selected ; and
as the embryonic development proceeds it must be
affected still more owing to the particular method of
receiving nourishment and the special position. The
insect pupa is a new structure of this character ; the
insects cannot possibly have had pupa-like ancestors,
as they would never have been able to nourish them-
selves. We saw in the preceding chapter how the
formation of the pupa came about.

All these divergences, modifications, and new forma-
tions, of which there is an immense number, must alter

1 For a brief account of the line of man’s ancestry the reader may
consult Haeckel’s “ Last Words on Evolution,” of which an English
translation has just appeared. (A. Owen & Co.) [d rans.]

CRUSTACEA AND MOLLUSCS

25 1

the course of the individual development to such an
extent that in no single case will it faithfully recapitu-
late the ancestral history. It is only rarely that the
biogenetic law will help the student to trace the stem-
history of an animal. That is not the purport of the
law. It serves rather to make more intelligible the
action of natural selection, which can only build upon
previous structures in the transformation of animals.
When we find ancestral traits in the embryonic
development of an animal, it is a proof of the theory
of descent, but we must not demand such fortunate
accidents. The ontogenetic evidence for phylogeny has
been so much distorted by natural selection that it is
probably the worst we have. It can only rarely serve
to illumine the darkness that lies on the past history of
organisms, and then generally only in conjunction with
the other two sources of evidence, the structure of
animals and the geological discoveries.

We started from the larva-form of the crustacean, the
nauplius. In that shape many crustaceans, such as the
small hoppers and the branchiopods, leave the egg, and
gradually pass into the adult form in the course of their
free life. Other crustaceans pass through the nauplius
stage in the ovum, and issue from it at a more advanced
larva stage, the zoea, which has a larger number of legs
and an abdomen. This is the case with most of the
higher crustaceans, such as the sea-crabs, which would
otherwise have to delay too long in the larva-stage on
account of their elaborate articulation and numerous
extremities. It is clearly better for the animal if the
time is not too protracted until it begins to lay eggs,

252 DARWINISM AND THE PROBLEMS OF LIFE

and so to maintain the species ; because during that
period it is exposed to all sorts of dangers. The craw-
fish, which is closely related to the marine crab, issues fully
formed from the egg. This, again, is an adaptation,
because the animal lives in running water, and cannot
use a larva-form which from its structure is intended
to float in the water. The stones afford shelter to the
young animal, and it can take refuge under them. It
is already a miniature of the adult.

Among the lower crustaceans, also, the copepoda
and water-fleas, there are differences of development.
The copepods, which swim about in countless numbers
in most ponds, lay a large number of eggs, and carry
them about for a long time in a little sac. These
numerous eggs have to be small, on account of the
lack of space and the slight quantity of food available
for each ; and as they contain little yolk, the animal
can only develop in them up to the nauplius-stage, and
must then issue forth. It is otherwise with the water-
fleas or daphnidae. In their case only a few eggs are
laid, and they have consequently more yolk. They also
lie in a special breeding-chamber under the mother’s
shell, and are washed with a fertilising fluid. Thus we
can understand how, in the case of the daphnid, the
whole nauplius-stage can be passed in the egg, and
from it issues a completely developed water-flea, only
differing from the adult in size.

The number of the enemies of the daphnidae is
enormous, and as the animals lay only a few eggs, they
could not survive if they had not a special adaptation
in connection with their fertility. They multiply

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253

parthenogenetically : that is to say, they lay eggs which
develop without being fertilised by a male. From
these eggs females only are produced, and they in turn
lay eggs that do not need to be fertilised. Hence the
water-fleas that appear in the spring are followed by
several generations of the same sex ; towards the end
of the summer their number is enormous, and then at
last males are developed from a few of the eggs.
These fertilise the eggs of the last generation of females,
which are only laid in small numbers, generally only
one or two. They are larger than the summer-eggs,
and have plenty of yolk, because they have not the
benefit of the fertilising water of the mother. They
have a thick shell, and fall to the bottom, where they
may be frozen in, or may lie uninjured without water.
In the following spring they produce the first generation
of females.

Parthenogenesis brings up the number of daphnidae
in the course of the summer to a huge figure. We saw
in the first chapter that a couple of foxes will, if they
have three male and three female young, and these
three pairs give birth to the same number and so
on, increase in ten years to 118,098 individuals. But
if the first pair of foxes only gave birth to females, and
these could multiply parthenogenetically, the number
would rise in ten years to 60,466,176, or incomparably
more. With larger figures the effect is still more
stupendous, as there is question of a geometrical pro-
gression. Hence the increase due to parthenogenesis is
so great that though the numbers of winter eggs in
each case is small, the total is very large on account of

254 DARWINISM AND THE PROBLEMS OF LIFE

the number of parents. They serve to secure the
maintenance of the species during the unfavourable
conditions.

The daphnidae are not the only animals whose eggs
develop without being fertilised by the male. Quite a
number of other species are associated with them in
this respect. Many species of small mussels increase
parthenogenetically as a rule ; amongst many of them
no males have yet been discovered, though they have
been carefully watched for years in an aquarium.
Parthenogenetic reproduction is also found in the
branchiopods and some other species of Crustacea, the
gall-flies whose sting causes the gall-nuts on our trees
and shrubs, and many lice, including the dreaded
phylloxera. They are especially animals that enjoy
from time to time very favourable conditions, which
they can make use of for most prolific reproduction,
and then pass into very dangerous and unfavourable
conditions, which they survive in the shape of fertilised
and hard-shelled eggs. Hence in this case fertilisation
is not directed merely to the multiplication of the species.
The best instance of this is the phylloxera.

In the spring the egg of the phylloxera produces a
female which multiplies parthenogenetically to an immense
extent, as the animals have an unlimited supply of food
in the shape of the vine-tendrils. All these females are
wingless, but after several generations the eggs produce
winged females which fly from stock to stock and spread
the species. They lay two kinds of eggs. The larger
produce females and the smaller males. Both are very
small and wingless, and cannot feed themselves. After

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255

their union the tiny female lays a single egg, which lasts
through the winter, and makes a beginning of a new
parthenogenetic generation in the following spring.

In this case it is clear that the union of male and
female does not lead to multiplication. On the contrary,
there is only one egg, and so one individual, from each
pair. If the phylloxera depended on sexual propagation
alone, it would soon become extinct. Its propagation
and multiplication are exclusively parthenogenetic.

But why do the males appear at all, we may ask,
when the phylloxera reproduces so much better
parthenogenetically ? And when we see that these
animals can dispense with sexual generation, why is
the same process not possible in other cases ? What
advantage is it to organisms that a new individual can
only be formed by the union of the generative products
of two sexes ?

We call the ovum and the sperm by the common
name of “germ-cells.” They are both the germs of
the new individual, and originally either the ovum, as
in our illustration, or the spermatozoon, could develop
quite independently into an animal. We shall see more
about this later on, but may point out here that the
spermatozoon and the ovum are structures of equal
value as regards heredity. The ovum contains the
bodily and mental characteristics of the mother and her
ancestors ; the spermatozoon the features of the father
and his ancestors. And just as a new individual can be
formed in the ovum from these characteristics by a
certain composition, as the above examples show, so
there is no essential reason why one should not be

256 DARWINISM AND THE PROBLEMS OF LIFE

formed in the same way from the spermatozoon. The
fact that the latter is much smaller and differently
shaped from the former is due to an adaptation which
we shall deal with later. This distinction only appeared
when it was no longer possible for the ovum or
spermatozoon alone to develop into a new animal, and
a conjunction of the two was needed. The blending of
the two germ-cells, the spermatozoon and the ovum, is
called amphimixis}

It was the introduction of this into the organic world
that deprived the two germ-cells of their independence ;
from that time there could be no reproduction without
union of the sperm-cells and ova.

As a matter of fact, amphimixis provides the start in
the formation of new individuals in the case of most
animals. But this is only its subsidiary purport, and
not the ground of its introduction, since the germ-cells
can grow into new individuals without amphimixis, as
we see in the daphnidae and phylloxerae. Its chief
significance is that before a new individual is formed
the characteristics of two animals must be blended.
The qualities of the father are contributed by the
spermatozoon : those of the mother by the ovum.
Thus the new individual has a selection of paternal
and maternal traits and of the ancestors on either side.
The nose, for instance, may follow that of the father,
or of the mother, or of any ancestor. How it is that

1 Weismann has shown that amphimixis (a name he has himself
invented) has originally nothing to do with propagation. It was he
who first adduced the parthenogenetic animals in proof of this con-
ception, and we shall generally follow him in our further observations
on amphimixis.

CRUSTACEA AND MOLLUSCS

257

of the many noses that are in a sense contained in the
fertilised ovum only one is developed and not several,
and what forces cause one property to be derived from
the father, another from the mother or an ancestor, are
questions involving general theories of heredity with
which we shall deal later. We will be content here to
establish the fact that there is a mechanism in the
fertilised ovum that builds up harmoniously the new
individual from the many characteristics it contains,
by always selecting one quality out of several equivalent
ones.

The great value of amphimixis is, then, that it adds
new and different paternal qualities to those that the
new organism receives from the mother, so that it has
a choice, and has a greater variety in its composition
than it would have without amphimixis. It is true
that even parthenogenetic offspring do not entirely
resemble the mother, because each ovum contains
variations, and many of the mother’s characteristics
appear slightly changed in her progeny. Nevertheless,
"such offspring will be more uniform in structure than
:others that suddenly receive a series of characteristics of
a totally different individual.

For these the constant re-combination of characters
in the offspring is of the greatest value ; it gives a wider
field of operation to natural selection. It enormously
increases the adaptive capacity of the animals, and the
variations from which one animal would arise here,
and another there, are united in one individual. It is
lue to amphimixis, therefore, that co-adaptations do not
need to be selected slowly and successively, but may

258 DARWINISM AND THE PROBLEMS OF LIFE

appear simultaneously, as we saw in the instance of
the heron, in which one animal is favoured on account
of the length of its neck, another on account of the
length of its bill, and their offspring may inherit both
features. In this way amphimixis may easily bring
about a difference between two similar structures. A
hare, for instance, may inherit short fore legs from a
short-legged mother and long hind legs from a long-
legged father ; and as this combination is useful in view
of its leaping, it may be further selected. Thus co-
adaptations are facilitated and accelerated by amphimixis;
the animals that are subject to it will be selected first,
and so we can see why amphimixis would be retained
in most animals, and why it is so wide-spread.

But it is also useful to organisms in another respect.
When an organ varies in any animal — let us say it becomes
larger — it may, of course, become smaller in the next
generation, but may just as well become larger. Many
experts believe, in fact, that there are definite directions
of variation ; that some internal or external principle
often presses them in the direction they have once
taken. We will discuss later on the possibility of this,
but we can in any case imagine that variations, especially
those that are only in two opposite directions, may take
the same direction for some time.

If any organ does vary in this way it may very often
be injurious to its possessor and bring about its
destruction. Excessive variations of this kind must
often appear, as chance may frequently lead to the
variation of an organ in a particular direction during
several generations. Amphimixis prevents animals from

CRUSTACEA AND MOLLUSCS

259

being destroyed on the ground of these excessive
variations ; it does not allow too great an advance of
the variations, because it crosses these animals with
others that have not the variation in question, or have
one in the opposite direction, so that the normal
standard is reached again in their offspring. Thus
excessive variations tend to disappear in the general
crossing, as amphimixis has an equalising effect.

We have already seen that the indifferent characters
of animals are preserved in the general crossing, because
the plus and minus variations neutralise each other.
Without amphimixis the variations would diverge in all
possible directions, and each animal would separate
further and further from the others. It would be

impossible to comprise a definite group together as a
species. Definite species are maintained entirely by
amphimixis. As the law of heredity explains the
resemblances of animals, so amphimixis explains that
its action marks off definite specific types from each
other in the world.

A further result of this levelling tendency of am-
phimixis is that isolated changes, even if they are
useful, cannot modify the species, because they are lost
in the general crossing. It is only when the majority
of a species that live together vary that the character
in question will be impressed on the whole species by
natural selection; in other words, only plural variations
are taken into account by natural selection. The
majority have, of course, only to influence the survivors.
If, say, a third of a species is extinguished every year,
iit is sufficient if a little over a third of the species has

260 DARWINISM AND THE PROBLEMS OF LIFE

the favourable variation, as the new character will then
predominate in the surviving two-thirds and be continu-
ously incorporated by amphimixis in the animals that
do not possess it, but survive, because the destruction
of the species is not great enough to involve them.
Thus amphimixis conveys a favourable variation to
animals that did not possess it. It qtiickly generalises
useful varieties, and the modification of the species
proceeds more rapidly than it could do without am-
phimixis. But it is clearly of great importance for a
useful variation to spread quickly to a large number of
animals, because of the great dangers that the animals
encounter from other sides against which the new
variation affords no protection. It is also due to
crossing that organs which have fallen into disuse
slowly disappear in all individuals of the species.

When we are asked if it is not expecting too much
of chance to demand that a variation shall occur in the
majority of the survivors, we can answer “ No.” There
are many changes that must be in one of two opposite
directions, and in these cases plural variations are quite
natural. There are many other variations in which
totally different characters may appear plurally, such as
the three lengthened parts of the heron we spoke of
previously and various shades in the protective colouring
of butterflies’ wings, if they increase the deception in
any way. In the case of many organs the only question
is whether they are better or worse, and all variations
that fall in the first category are preserved as plural
variations.

In this way a gradual transformation of the species

CRUSTACEA AND MOLLUSCS

261

is brought about. Still, natural selection may, of course,
act with such intensity as to give predominance to a
small number of animals that possess a variation, and
leave all their fellows to be destroyed. Thus in very
severe cold a few deer with particularly thick coats may
be preserved.

It is due to amphimixis alone that the species remain
within their limits for thousands of years. If the
variations were not constantly neutralised, they would
long ago have modified animals so much that they
would no longer have the least resemblance to their
ancestors. If it were not for amphimixis there would
not be to-day any fishes resembling the fishes of earlier
days.

On the other hand, amphimixis allows no division
of a species. How can a new species be developed
from an older one, and this be preserved, if the
promiscuous crossing is continually at work destroying
or generalising all new characters? In that case, we
can safely say, there would not be a number of different
species if there were not a force that prevented the
crossing of the members of the new species with those
of the parental stock. We have alluded several times
already to this force. It is isolation. We shall deal
with it in the tenth chapter, and see why there are
many different species, when we have learned why the
species may be arranged in a system according to their
greater or less resemblance, and why there are unifying
types of species. But we have other questions to
answer first.

CHAPTER VIII

WORMS AND CCELENTERATA

Genealogical tree of the animals. Descent of animals. Descent
of man. Preservation of intermediate forms. The earth-worm.
Regeneration. Leeches. Parasitism. Origin of parasites from
free animals. Organic changes in parasites. How parasites are
conveyed. Exchange of hosts. Life of the chief parasites,
trichinae, maw-worms, dochmius, tape-worms, etc. Danger of
taenia. Development of the liver - distoma. Friendships of
animals. Symbioses.

We have already passed in review three stems of the
animal world : the vertebrates, articulates, and molluscs.

We may regard these three groups as sisters, as they
proceed side by side from a fourth or parental stem.
This consists of the worms or vermalians.

The worms are primitive forms whose origin goes
back long before the geological records commence.
It is their simple organisation that makes it possible
tor stems to develop from them in three such different
directions.

We have, then, so far considered the three chief
branches of the tree of organic development, and we
now come to the trunk in which the three branches
unite. From this point we shall follow the stem down
to the lowest point of its roots. That is as far as the
eye and microscope can reach. The ultimate fibres of

262

WORMS AND CGELENTERATA 263

the roots are so fine that they lie entirely beyond our
range of vision.

The protozoa represent the point at which the root
becomes thick enough to be seen by us. These are
the simplest organisms known to us, and their origin
goes back to an incalculably distant period. From them
were developed the ccelenterata, which we will consider
at the close of this chapter. After these come the platodes
— animals that approach closely to the coelenterates in
structure ; in both, for instance, there is only one aperture
in the body, and this has to act both as mouth and anus.

From the platodes (or “flat worms”) descended the
round worms, which have mouth and anus, and an
alimentary canal suspended in a spacious body-cavity.
However, their organisation is still very simple. Their
type of structure is retained fundamentally in all the
higher animals, as they are the ancestors of the verte-
brates on the one side, and the molluscs and articulates
on the other. We may mention as a fourth daughter-
stem the echinoderms, the star-fish and sea-urchins, of
which there are many species in the sea.

It was a fortunate chance for science that the
transitional forms from the vermalians to each of the
four stems are still in existence. Where they are
missing, the gap is filled by larvae forms. Thus the
larva of certain molluscs and of the echinoderms
resembles a certain order of worms, the microscopic
rotifers that are found in all water. The lowest forms
of the vertebrates lead on to a group of animals called
the tunicates, which have a good deal of affinity to the
worms in their structure.

264 DARWINISM AND THE PROBLEMS OF LIFE

The round worms do not represent the highest class
of the vermalians. There is a much more advanced
section, the annelides. To this group belongs the earth-
worm ; it has a very elaborate structure, but its marine
relatives are much more highly organised. They are
predatory animals with sharp eyes, and swim briskly in
the water in search of their prey.

From the annelids have come the articulates : the
crustaceans on one side, and the tracheates on the
other. Of the former no transitional form has been
preserved, but this is not so with the latter ; in fact,
this particular animal, the peripatus , is the most typical
instance of a transitional form that we know. Half-
annelid and half-myriapod, it seems to have one organ
of the worm-type and another of the tracheate. The
peripatus is found in various species, but only a very
few ; and this is true of all transitional forms. It is
clear that animals of this kind, which have neither the
adaptations of their ancestors nor their descendants in
complete form, are easily crushed out by the two, and
can only be preserved in sheltered localities. When
we recollect, in addition, the eternal changing and re-
adapting in nature, we are surprised that any typical
transitional form has chanced to survive to our time ;
but we must not ask the theory of descent to justify
itself by producing actual instances of transitional forms.

When we say that the vertebrates have been
developed from the vermalians, it must not be sup-
posed that any living animals, such as the maw-worms,
were their ancestors. We cannot assume that these
ancestors had relatives whose descendants are still

WORMS AND CCELENTERATA

265

preserved quite unaltered. The maw - worms, for
instance, have many adaptations that they have
acquired since that time in the course of the earth’s
development, and we do not know if they had not at
that time adaptations that they have since lost. Thus
we cannot form any absolutely safe picture of the
primitive worms that became, in certain circumstances,
the ancestors of the vertebrates. We can only say that
they had the worm-type ; that their principal organs
had, in general, a structure and arrangement more
closely resembling that of the worms than any other
living animals.

Thus the statement that “ man descends from fishes ”
does not mean that we have ancestors who resembled
any of the actual fishes, but that at a certain period they
were gill-breathing, aquatic animals with a structure to
which the nearest approach is found among the fishes of
all actual animals. So, again, man does not descend
from the apes, as is often said, but from beings that
must probably have resembled the actual apes more than
man. The apes have not been fixed in their organisation ;
they have diverged steadily from their ancestors by
constantly acquiring new adaptations. Their ancestors
were probably brothers of man’s ancestors, but that does
not justify the above statement. On the strength of
this probability we may, at the most, say that man and
the ape have a common ancestor . 1

There are scientists who do not admit that man had ape-like
ancestors. They believe that the apes are no more clearly related to
man than the ruminants or carnivores, or, especially, the kangaroos.
1 his view, however, has few supporters, and its arguments are not at
all convincing.

266

DARWINISM AND THE PROBLEMS OF LIFE

The most familiar representative of the present stem
is the earth-worm. It is true that most people’s
acquaintance with this animal is superficial, as its
subterraneous habits prevent more than a few from
knowing it thoroughly. For a long time, in fact, the
animal, which is not merely harmless but extremely
useful, was decried as injurious, and there are still
people who kill it whenever they find it.

Darwin was the first to show that the earth-worms
are indispensable to the plants. He pointed out that
they act as ploughs in loosening the earth. The
animal feeds on the digestible elements in the soil. It
eats its way through them, as it were, passing them the
whole length of its alimentary canal, and then ejecting
them, which is always done on the surface. Thus the
finer constituents of the soil are constantly brought to
the top by the worms, and we have always good soil
there. The many passages that the worm leaves
behind it in its travels loosen the ground more and more,
and as they fall in, the elements of the soil rub together
and grind one another. Finally, leaves and other
bodies are drawn by the animals into their tubes, ground
up, and brought to the surface again. However strange
it may sound, we have to admit that the whole mass of
the fruitful surface of the earth has passed through
the alimentary canal of earth-worms, and passes through
the same process every few years.

Man’s attempts to trap the worm have, fortunately
for it, hardly any success. But the defenceless animal
has a good deal to suffer from other enemies. Besides

WORMS AND CGELENTERATA

267

moles, shrew-mice, birds, lizards, amphibians, insects,
and many others, it is the myriapods, especially, that
pursue it into its own tubes. We often see the worm
creep in terror from its passages in full daylight to
escape these dreaded enemies.

The danger of being captured is less fatal to the
earth-worms than to other animals, as they have a
great power of regeneration, and can lose a part of their
body without perishing, because they can replace it.
One can cut a worm into two parts, and one part —
often the second one as well — will always regenerate the
lost piece. If it is cut into several pieces, there is never
more than one new animal, and often none at all ; and if
it is cut longitudinally into two halves both of them
very soon die.

Here again we see that the power of regeneration
is an adaptive phenomenon, and does not act in rare
situations. What generally happens is that a piece is
torn off an earth-worm, and the rest of it retreats
underground. This mutilation would soon extinguish
the animals if it were fatal to them ; and the other
injuries happen too rarely for natural selection to have
provided a remedy against them.

In the near relatives of the earth-worm, that live in
water, such as the lumbriculus , the regenerative power
is much higher. One of these animals has been cut
into fourteen pieces, and thirteen of these formed new
worms. These animals are devoured on all sides, and
their enemies, the water-insects, have sharp jaws with
which they cut pieces out of them. There are various
species of aquatic worms, and in each of them it can be

268

DARWINISM AND THE PROBLEMS OF LIFE

shown that the regenerative force is proportionate to the
kind of mutilation to which they are most frequently
exposed.

Thus the leeches, which are dreaded and not much
exposed to mutilation, have no power of regeneration.
The medicinal leech is still very common in France and
Hungary, and is a great trouble to bathers, as it gathers
in swarms at the first splash. Much less troublesome
are the large leeches that are found in the ponds, and
known as horse-leeches ; these may be taken in the
hand without fear. Their teeth cannot bite through the
human skin ; they can only pierce the mucous lining of
the nose, the mouth, and other parts. One species of
the horse-leech, the Atilastomum gulo , feeds on snails,
and does not generally indulge in blood-sucking : the
other species, the Hceniopis vorax , may become a great
nuisance by getting into the throats of horses and cattle
when they bathe, and attaching themselves to the soft
parts. But this hcemopis plague is only found in North
Africa.

There is also in our ponds a worm about as thick as
a violin-string, and sometimes a foot in length. It looks
like a horse-hair, and, as a matter of fact, the rustics
have in many places fastened on to it the legend that it
is a living horse-hair, travelling about in the water and
able to penetrate the human skin. In reality the animal
is quite harmless, and is, in fact, unable to maintain
itself ; it lives only a short time, and uses this for laying
its eggs. From these develop tiny larvae with a pointed,
zigzag boring apparatus, which pass through the skin
of May-flies and gnat-larvae, live in them for some time,

WORMS AND CCELENTERATA

269

and surround themselves with a capsule. If the larva
is eaten by a larger insect, the capsule bursts in its
stomach, the worm becomes free, and develops to the
adult stage in its new host ; it abandons this home in
wet weather, and returns to the water to lay its eggs.

The life-story of this Gordius aquaticus brings us to
one of the most interesting phenomena of the animal
world, parasitism. There are many parasites among its
relatives, the nematodes, which form the lower class of
the round worms ; but there are still more amongst the
platodes. Generally speaking, the vermalian stem is
the richest in parasites in the whole animal world, the
articulates alone approaching them in this respect. In
comparison with the parasites of these two stems, the
rest are insignificant ; the protozoa alone of other groups
provide a large number, including the notorious malaria
parasites. In the plant world again we have the bacteria
and other fungi.

Rudolf Leuckart, the chief authority on the subject,
defines parasites as creatures that find food and shelter
in a living organism. According to this definition there
are, of course, parasites amongst the plants, some with
other plants, some with animals, as hosts. In our view
of the origin of living things all parasites must have
descended from free-living organisms.

This statement can easily be proved in the case of
animal parasites. We have already seen something of
parasitic crustaceans. We saw that they pass their
youthful stages as free organisms, and can hardly be
distinguished from those of other crustaceans. We may
now add that we find a large number of transitional

270 DARWINISM AND THE PROBLEMS OF LIFE

forms amongst the parasitic crustaceans, some of which
are entirely like the free animals, and differ from them,
perhaps, only in having longer claws, with which they
attach themselves for a time to other animals and derive
their food from them. But the longer the animals live
on their hosts the more profoundly are they modified ;
the legs, which are no longer necessary, degenerate
more and more, the sense organs disappear, even the
alimentary canal may atrophy, and the animals feed, as
the sacculina does, in plant fashion, by means of roots
passing into their host. The structure is also entirely
changed by the enormous development of the sexual
organs, which are of great importance in every parasite.

Of the tracheates there are lice and fleas, which
ordinary folk call insects. Here again there are animals
that have been most curiously modified. We have an
instance in the Pentastomum tamioides. This animal,
which looks very much like a tape-worm, as its name
suggests, and has very little of the characteristics of a
spider, to which it really belongs, lives — though rarely —
in the nasal cavities of the dog. The eggs pass through
the nostrils to the ground, and when a hare or rabbit
takes them into its stomach with the grass, larvae issue
from them, pass through the stomach into the liver of
the ruminants, and cover themselves with a membrane,
inside which they cast their skin several times in the
manner of the articulates. When they have grown
bigger, they break the capsules, and disperse through
the various passages of the liver. They then bury
themselves in capsules once more, and if their host is
devoured by a dog or a fox they develop into sexually

WORMS AND CCELENTERATA 27 I

mature animals inside it. They are often so numerous
in the hare as to cause its death. They are less
dangerous to man, who also may be infected with them,
the eggs being received on the hand from the dog’s
sniffing and being passed to the mouth.

This pentastomum is a thorough parasite, and changes
its host ; this, as we shall see presently, is characteristic
of the majority of intestinal worms, which are, so to say,
the most complete parasites. We can, however, find
transitional forms even amongst these, leading gradually
to them from their free-living relatives. Amongst the
nematodes many species are still perfectly free ; among
the platodes the tape-worms descend from the suctorial
worms, and these are closely related to the turbellarians,
small, flat, dark or light worms that we find in every
pond.

Parasites are, therefore, animals that have adapted
themselves to living on other animals. This kind of
life is clearly a very safe one. Living in the warm
interior of the host, the parasite is almost entirely
sheltered from climatic troubles, and has nothing to
fear from direct enemies. Finally, it riots in an abund-
ance of food, and this is often brought to him already
digested. This is the case with the parasites of the
alimentary system, which are surrounded with a
constant stream of nourishment, and have often even
lost their own alimentary canal, as the food can pass
directly through the wall of their body, without having
to undergo further changes within the body of the
parasite.

Thus we find no alimentary system either in the

2 7 2 DARWINISM AND THE PROBLEMS OF LIFE

tape-worm or the echinorkyncus / and in the nematodes
it is at least very much simplified, and is devoid of the
subsidiary glands such as the liver and other appendages.

The locomotive organs of the parasites are equally
degenerate, and are replaced by clinging apparatus.
There is bound to be such an apparatus in external
parasites, otherwise the unwelcome guest could easily
be rubbed off when they are not concealed from their
host by a thick coat of hair. And clinging organs
are necessary in intestinal parasites, as they could
not stand against the pressure of the fluid food
if they were not attached, and would be forced out at
the anus. It is only the maw-worms and other thread-
like worms that can maintain themselves in the £ut
owing to their shape alone. As they are long, at the
end thin, and round, the chyle runs past without bearing
them along with it.

Being cut off from the outer world, the parasite has
no need of sense-organs, and is usually without them.
Its respiratory organs are less altered, and hence it is
that the gill-breathing Crustacea only attach themselves
to aquatic animals, and the air-breathing tracheates
only, as a rule, to land-animals. The ancestors of the
intestinal worms breathed through the skin, and this
has been preserved in their descendants, who can do
so because they are constantly bathed in the fluids
of their host that contain oxygen. It is due to this way
of breathing that they are found both on land and

1 These are round worms, often of a considerable size ; their snout is
equipped with spines with which they fasten themselves to the wall
of the gut. They are generally found in fishes and aquatic birds,
more rarely in mammals, and very rarely in man.

WORMS AND CCELENTERATA

273

water-animals, and are therefore the most widespread
of all parasites. In many of the tracheates parasitism
has gone so far that their respiratory organs have been
affected. Thus the pentastomum we referred to above
has lost its tracheae, and breathes through the skin,
like the worms.

We have now seen that the nature of parasitism
entails a simplification of many organs, but other organs
are all the more elaborately developed in parasites.
These are the sexzial organs. In the first place, it
is very easy for the parasite to supply them with plenty
of food. It is devoid of so many organs that require
their proportion of the food in other animals. Hence
we find, as a matter of fact, the sexual organs of
parasites swell in proportion to the thoroughness of
their parasitism. When we study the anatomy of a
distomum we have some difficulty in finding the other
organs on account of the pronounced sex organs. In
the tape-worm the other organs occupy an evanescent
space in comparison with the testicles, the ovary, and
their glandular appendages.

It is not merely possible, but necessary, for the
parasites to have this preponderant development of the
sexual organs. It is just as difficult for the parasite to
maintain its species as it is easy to support itself.
When the host, especially of internal or fixed para-
sites, perishes, the parasites must die also, as a rule.
Hence its ova must always be conveyed to new animals.
In the case of the sacculina this is comparatively simple,
as we saw in the last chapter. From the egg is
developed an active larva, which seeks a new host. But

2 74 DARWINISM AND THE PROBLEMS OF LIFE

how can this be done on land, and in the vertebrates
that shelter most of the parasites? In some cases, such
as the gourd-worm ( distomum ) and the broad tape-worm,
an active larva develops from the egg, falls into the
water and enters a mollusc or a fish. But in this the
animal has not reached its definitive host, the sheep or
man. The larva has to be conveyed from the interior
of the aquatic animal to the stomach of the mammal,
and this is done by the former being eaten, consciously
or unconsciously, together with the larvae by the eater.

This passive transition, which we shall study more in
detail afterwards, is the only possible means of surviving
for most parasites. In only a few cases is an active
larva developed from the egg ; as a rule the eggs must
be licked up and taken into the mouth of a host, and
even then the end of the parasite’s development is not
reached. The host must be eaten, and the larva; pass
in its flesh into the interior of their principal host, where
they come to sexual maturity. Thus chance plays a
great part in the maintenance of parasitic species, and
in view of the slender prospect that the individual egg
has of ever being developed, we can understand why
they are laid in such vast numbers, sometimes up to
100,000,000.

The eggs, which lie on the earth after leaving the
host and usually have to wait a long time before they
reach the stomach of an animal, need a high power of
resistance. As a rule they have a shell and plenty
of yolk ; this in turn requires organs in the mother’s
body that are capable of meeting these demands.
Hence there are yolk-bodies and shell-glands, as well as

WORMS AND COELENTERATA 275

large ovaries, which greatly complicate the sexual
apparatus.

In fact, we very often find both sexes united in one
parasite, and we then call the animal an hermaphrodite.
This is not difficult to understand. The parasite is
often alone in its host, as is generally the case with
the tape-worm ; and it has then to develop both
spermatozoa and ova, or remain barren. Sometimes,
it is true, there may be two or more tape- worms in one
host, and this is more frequent in the case of other
parasites. Then mutual fertilisation is possible.
Hermaphrodism has been introduced amongst the
parasites to prevent the animals that live in isolation
from perishing without doing something towards the
maintenance of the species.

We have now examined the organisation and habits
of parasites from our point of view, but there is one
point we have not yet considered — the change of hosts.
This plays a very important part in parasites, and we
have already referred to several that pass their early
stage in one animal and come to sexual maturity in
another. An attempt has been made to explain this
remarkable phenomenon by regarding the first host
as the original one, in which the parasite became
sexually mature in former ages. After the rise of the
vertebrates it adapted itself to these, so that the
parasites taken with the flesh of the first host into the
alimentary canal of the second did not die, but only
reached sexual maturity there, as the conditions are
the best conceivable for parasites in the vertebrate. A
good deal can be said in support of this view, especially

276 DARWINISM AND THE PROBLEMS OF LIFE

the fact that the stages of the parasites in the first hosts
have some resemblance to their primitive forms, from
which we may infer that these stages were at first
sexually mature animals.

However, we will not linger over these theories,
but pass on to study the life-story of some of the
chief parasites. In this we shall see what a wonderful
adaptiveness there is in these creatures.

One of the worst human parasites is the trichina.
The man who is visited by this dire guest has often to
pay for it with his life. It is chiefly on its account that
the examination of meat has been introduced, and
this and the now prevalent custom of killing in
abattoirs have greatly diminished the danger from
trichina.

The trichina is found in a large number of animals,
but only one of these, the pig, calls for our notice. It
often lives in great quantities in the flesh of pigs, in the
shape of a small white point ; this is a capsule, and the
tiny worm is rolled up spirally inside it. If the pig’s
flesh containing the capsules enters a man’s stomach,
the capsules burst and the little worms issue forth ; they
travel into the small intestine and there reach sexual
maturity within a few days. The females give birth
to an enormous number of young, and then die. The
young pass through the wall of the intestine, which they
can easily do on account of their small size and pointed
shape, and travel gradually by the blood-vessels into the
man’s muscles. There they feed for a time on the
decaying muscular matter, until this in turn secretes a
membrane to protect itself against the parasites. This

WORMS AND COELENTERATA

277

membrane is strengthened by the worms themselves,
and coloured white by deposits of lime. The animals
have now entered on a condition of repose, and will
only re-awaken into life when the muscles they reside
in reach the stomach of a new animal. When this
capsule stage is reached — about three months from the
first infection — the danger is over. But many people
die before this through the irritation of the intestines,
and especially through the inflammation of the muscles
affected.

When the trichinae enter human beings their career
is virtually over, because no one can be infected by
eating human flesh. It is otherwise with the animals.
Rats are the chief victims of these parasites, as in their
case the cycle of migrating and capsulating begins
afresh, the dead or diseased rats being eaten by their
fellows. This would not affect human beings if the rats
did not make their way into pig-styes, where they are
'■eaten by the pigs when they die, or even when alive.
Thus the worms capsulated in the rat’s flesh pass into
the stomach and the muscles of the pig, and may come
to infect human beings.

Among the nematode worms there is a large number
•of parasites. Most of those in Europe that can infest
human beings are of a harmless character. The human
maw-worm, the female of which measures up to ten
inches, and the much smaller oxyuris (two-fifths of an
dnch), are common in children. These two species have
mo temporary host; their eggs, and often the whole
;animal, are passed by human beings, and if they find
itheir way into the human intestines once more, they

278 DARWINISM AND THE PROBLEMS OF LIFE

develop at once . 1 This can easily happen in bed, and
also in other ways. One of the chief transporters of
them is the fly, which settles on excrements as well as
on food.

But though these worms are often present in great
quantities, they are generally only a nuisance and very
rarely dangerous. The latter applies more frequently
to a relative of theirs, the Dochmius duodenalis. This
worm, somewhat larger than the oxyuris, has strong
jaws with which it attaches itself to the wall of the
intestine ; it pierces this with the stiletto it has in its
mouth and causes frequent hemorrhage, sometimes
causing death and always anaemia. The ova of the
parasite are ejected by the anus, and develop in mud
or moist earth into tiny larvae, which give fresh dochmii
when they re-enter the human intestines. Hence the
disease occurs particularly in people who are compelled
to drink muddy water, like the Egyptians, or any who
work much in moist soil, such as brick-makers. It is on
this account that the workmen in the St. Gothard tunnel
had to suffer so much from dochmii. It was through
the tunnel that the worm was introduced into Germany.

In these instances we have followed a simple develop-
ment of parasites, but we now turn to animals with a
much more complicated life - story. These are the

1 In the case of the oxyuris the eggs develop very quickly, so that
self-infection is always occurring, but the egg of the maw-worm needs
months before it will develop into a new animal if re-introduced into
the human body. In this case, therefore, the infection is not so direct
as in the oxyuris ; it usually comes aboutfthrough drinking meadow-
water, or putting grass in the mouth, which may also bring one the
much more mischievous echinococcus that we will describe presently.

WORMS AND CCELENTERATA

279

platodes (“ flat- worms ”). We will begin with the most
familiar order, the tape-worms.

There are two tape-worms especially that are parasites
on the human intestines, the Tania solium and the
Tania, saginata. Both consist of a series of connected
segments, very narrow at the head and broadening
towards the end. At the end, also, the sections are
sexually mature, and contain a vast number of fertilised
eggs ; these are detached from time to time, and pass
out with the excrement. The sections of Tania solium
are comparatively inert after ejection, but those of
Tania saginata can crawl about ; they often make their
own way out of the anus, and have been seen to climb
up the wall of a room.

The two also differ in the armament of the head. In
Tania solium there are four suctorial disks which cling
to the wall of the intestine, and are assisted in this by
a fringe of hooks. The latter are not found in Tania
saginata , yet it is more difficult to get rid of, as its
suctorial disks are larger and more powerful. Often
a slight remedy will bring away the greater part of the
body, but that is no use to the patient, as the head is
able to form new parts.

If the sections of Tania solium that contain the eggs
lie on the fields amongst human excrements and are
eaten by pigs, which do not disdain such food, the shells
of the eggs burst in the pig’s stomach. A tiny creature
emerges, bores its way through the wall of the intestines,
and gradually reaches the muscles. Here it assumes
an oval shape, and forms a membrane round itself,
which is further strengthened by a secretion from the

280 DARWINISM AND THE PROBLEMS OF LIFE

pig’s muscles. Fluid passes into the capsule from the
surrounding tissue, so that it may swell to the size of
a pea. The animal itself remains at the globule-stage,
and grows very little inside it. It forms the head of a
future tape-worm, and remains at this stage in the
muscles of the pig. At this period it is known as
a scolex or measle-worm.

If the infected flesh of the pig is eaten by a human
being, the measle-worms are set free, and the small tape-
worm head makes its way into the intestine, and attaches
itself to the wall. The vesicle hangs on to it for some
time, but is at last cast off, and the head begins to form
the segments until the animal has reached its full size
of more than three yards.

The development of the 7^-8^- yards long Tania
saginata is similar to this. But in this case the eggs
must be taken into the stomach of a cow, if they are
to become scolices ; the pig digests them. Hence it
is that in this case the parts of the worm have
developed the power of motion, as the cow does not
eat faeces like the pig ; but it can very well happen
for the cow to swallow a part of a taenia clinging to
a blade of grass, or grass covered with its eggs. But
there is a second difference of more importance to
human beings. While the eggs of Tama saginata
may safely be eaten by human beings, as they cannot
develop in their alimentary canal, it is otherwise with
Tania solium. In the latter case infection is possible,
as the eggs produce larvae in the human intestines as
well, and these pass into the muscles, and enclose
themselves in capsules as large as peas. If they

WORMS AND CCELENTERATA

28 l

reach the eye — which has often happened — they
cause blindness, and it is still worse if they reach the
brain. Hence a man who is infected with Tania
solium is in a condition of great danger to himself
and those about him, as new infection is very possible.
It also happens that in vomiting the sections pass
from the intestine into the stomach, and the larvae
are set free there. This is a moment of great
danger to the patient, as it is always the larva-
stage that may cause death ; the adult tape- worm
is not dangerous. A man with Tania solium
should, therefore, get rid of it as soon as

possible.

Still worse are the scolices of the Tania echinococcus.
This tape-worm is only one-fifth of an inch in length,
and is found in large numbers in the intestines of
the dog. The detached parts are very active ; they
climb up stalks of grass, and are likely to be eaten
by hares, as well as by cattle, sheep, or pigs. The
larvae that develop pass into the muscles, but before
the formation of the head begins, they grow so large
and soak up so much fluid that they cause blisters as
big as a child’s head, which are generally fatal to the
victim. The head of the echinococcus does not begin
to form until after this swelling. Man may eat these
larvae with impunity, as they do not develop into tape-
worms in his intestines ; they do so, however, in the
dog. But if the eggs of the echinococcus get into the
human mouth and stomach — and the dog will often
give them an opportunity to do this, as it licks its
anus as often as it does the hands (or even the

282 DARWINISM AND THE PROBLEMS OF LIFE

mouth) of its master 1 — the large vesicle is formed in
the muscles, generally in the liver, but sometimes in
the brain. Death follows in most cases.

Thus the Tania echinococcus and the Tania solium
are found in man in the shape of scolices, and these
particular tape-worms are accordingly to be dreaded.
Another parasite of the human intestine is the broad
tape-worm, the Bothriocephalus latus , which grows to
a length of thirteen yards. We have referred pre-
viously to its migration. Differently from the tania ,
it develops from the egg a larva that enters a fish,
if it reaches water, and incapsulates itself, without
forming a vesicle. It at once forms the head of the
future tape-worm, which develops in a new host that
has eaten the fish. Human beings get the worm by
eating underdone pike or turbot.

This kind of migration brings us to the other
parasitic platodes, the suctorial worms. They are
rarely found in man, and are never dangerous — in
Europe, at all events . 2 But they are a great plague
to other animals, such as sheep, birds, and frogs.
The fluke or gourd-worm, shaped like the kernel of
a gourd, the Distomum hepaticum , is found in the
sheep’s liver, or rather in its gall-duct. Its eggs pass
by the gall-duct into the gut, and then out with the
excrements. If they fall into water, minute, lancet-

1 People should, therefore, be careful with dogs. They should at
least wash their hands after touching them, and should never let dogs
kiss them.

2 In Egypt the Bilharzia hcematobia is one of the most dangerous
parasites. It lives in the human blood-vessels, especially the portal
and urinary veins.

WORMS AND CCELENTERATA

283

shaped creatures develop from them ; these swim
about, and bore into a water-snail, in the interior of
which they grow into tube -like bodies. Inside the
tubes are a quantity of small, tadpole-shaped creatures.
These abandon the tube and the host, and seek a
new victim, inside which they incapsulate themselves ;
though they may do this, without migrating, on
aquatic plants. If the sheep eat these plants, the
distoma develop from the capsules in their intestines,
and pass on to the liver. The other species, which
have incapsulated in a second host, reach sexual
maturity when the new host is eaten.

The adaptations of the distoma are enormously
varied, and may be very complicated. Especially
interesting is the Distomum macrostomum , which is
found in birds. When the eggs of this animal reach
the plants that grow on the edge of brooks and ponds,
they are swallowed by the snails, which gnaw the
plants. In these they develop into curious tubes that
surround the intestines of the snail, and also run out
into its feelers, which they distend and distort into thick
tubes. Inside the tubes, especially those in the antennae,
the young distoma are developed, and the tubes contain-
ing them now become coloured with green and white
bands, and move about. The movement increases, the
snails antennae burst, and the tubes fall to the ground,
where they creep about and look very much like insect-
larvae, or caterpillars. The birds really take them to be
edible animals of that kind, swallow them, and so take
the brood of distoma into their bodies, where they reach
sexual maturity. Here we have a most peculiar case of

284 DARWINISM AND THE PROBLEMS OF LIFE

adaptive colouring - . Most animals need their colouring
as a protection against their enemies, but in this case we
have organisms that are coloured for the purpose of
getting eaten. However, the life-story of the animals
enables us to understand this remarkable adaptation.

We will not explore any further the interesting field
of parasitism. We have examined the various forms of
parasites and their habits so closely, because they make
it so clear that there are no insuperable limits fixed to
the variations of animals. As a matter of fact, we dare
not say that natural selection could not give wings to a
horse. If there were some necessity and sufficient time
for such a transformation of the horse, the required
variations would certainly not fail. The creation of a
pegasus is not more wonderful than the transformation
of a spider into a tapeworm-like animal. Natural selec-
tion is omnipotent in the creation of forms of life. It
is restricted by no limit that lies in the nature of things.

• ••••••

There is a certain resemblance to parasitism in a
phenomenon that leads us on to the ccelenterata. This
is symbiosis , or community of life.

When we put water and plants from a pond into an
aquarium, we often notice on the glass, some time after-
wards, a green tube, as thin as a needle, with long
threads hanging from the end of it. If a water-flea
touches one of these threads, it remains sticking to it,
and is conveyed into the tube, where it disappears.

This small, tubular creature is the green water-
polyp, one of the few fresh-water representatives of
the coelenterata, which are found in many brightly

WORMS AND CCELENTERATA

285

coloured species in the sea — medusae, anemones,
sponges, etc. — and are one of its chief ornaments.
One other relative of the green polyp, the brown
polyp, is often found in our waters, and also the
fresh-water sponge, which is often found on pieces of
wood and branches at the bottom of ponds.

Let us return to the animal we mentioned first, the
hydra, or green polyp. When we examine it with the
microscope, we find that its colour is due to very small
granules that pervade the animal. These granules are
independent organisms, algae, that live in the polyp,
without suffering any injury, or doing any to the hydra.
The joint living is beneficial to both organisms. The
algai have a pretty well-assured maintenance in the
ccelenterate, while this in turn benefits by the oxygen
they secrete. Here we have a case of symbiosis — a
joint life of two organisms, based on mutual advantage.

There are a large number of these symbioses. Certain
marine Crustacea, that live in snail-shells, always carry
on them anemones, ccelenterates that secrete a stinging
substance when they are touched that paralyse many
organisms. The sea - anemones have this advantage
from the transportation that it enables them to obtain
food more easily than they would do otherwise, since
they have no power of locomotion. On the other hand,
the crustaceans are protected by the anemones from
their enemies, because if one attempts to drag them
from their shell, the coelenterate plies its batteries and
the assailant has to withdraw. There is another
instance of symbiosis in the relation of ants and lice.
We generally find ants running about on plants with

286 DARWINISM AND THE PROBLEMS OF LIFE

certain species of lice on them, and it is easy to see
that the lice have the advantage of being protected from
many enemies by the presence of these stalwart com-
panions. On the other hand, the ants are fond of the
faeces of the lice, which are as sweet as honey . 1

Symbioses between plants and animals, or between
plants and fungi, are much more common than between
two species of animals. That is easily explained.
Animals are rivals in the struggle for life, but plants
have a different kind of food and respiration ; in fact,
the latter difference makes the proximity of plants
healthy, and often indispensable, for animals. The
fungi are in the same position as the animals.

Hence besides the hydra, certain protozoa are
inhabited by green algae ; and the best known instance
of a symbiosis between fungi and algae is found in the
lichens, which are not single organisms, as one would
infer from their appearance.

1 There are also symbioses between higher plants and animals. Thus
in South America the trees are threatened by the leaf-cutter ants.
They cut off the leaves with their shear - like jaws, and gather them
into heaps, on which they grow fungi. Certain plants, the imbauba, or
chara, are protected from these enemies by harbouring fighting ants of
a different species, which drive off the leaf-cutters when they come.
But in order to induce the tree-ants to remain outside the tree, so as
to perceive the approach of the enemy — which would often be impossible
if they were always inside — the tree has developed special nutritious
pods at the threatened points — the stalks of young leaves — which the
ants constantly gather for their young inside, and so they are always
found at these spots.

This case, again, cannot be explained on the Lamarckian principle.
The nutritious pods that are formed by the plant for the ants, and that
are wanting on trees related to the imbaubas which have no ant-guests,
cannot have been produced either by the will of the plant or the
repeated bites of the insects. Hence the explanation of symbiosis as
an inherited habit does not hold in this instance.

WORMS AND CGELENTERATA

287

Symbiosis exhibits an entirely new side of natural
selection to us. In this case the principle that seems to
be the foundation of all life, the struggle of all against
all and the crushing of one organism by another, is
thrust aside. Symbiosis teaches us the omnipotence of
natural selection more clearly than any other phenomenon
in nature.

CHAPTER IX

PROTOZOA

The animal built up of cells. Principle of division of labour. The
greater the division of labour, the higher the animal’s organisation.
Multicellular and unicellular animals. The protozoa, their form
and reproduction. Structure of an animal in its development
from the ovum onwards from rudimentary parts. Origin of the
germ-cells. Outlines of a theory of heredity. Amphimixis of
the protozoa. Origin of sexual reproduction. Formation of seed
and ova. Continuity of the germ-cells. Are any animals
immortal? Death is not common to all animals. Origin of
death. Permanent and temporary life. Has life come from the
stars? Origin of life on the earth, spontaneous generation. How
it is to be conceived. The first development of living matter.
Formation and significance of the cell-nucleus. Significance of
the fundamental parts. Relation of the rudimentary parts in
amphimixis. When life is extinguished.

To a certain extent we may compare organisms to
edifices in our towns. Just as our buildings differ
enormously in size and structure, yet are generally
composed of the same elements, the bricks, so we find
the same elementary units in all vegetal and animal
bodies. In the course of its embryonic development
every organism is built up like a house. Its life
begins with one structural element. To this numbers
of fresh ones are added until at last the highest point
is reached ; the living thing has attained its full size,
and it would be idle to attempt to count its constituent
units.

288

PROTOZOA

289

The fundamental elements of organisms are called
cells . 1 With a few exceptions the cells are too small
to be seen with the naked eye ; they can be seen with
the microscope as corpuscles of various shapes. But all
of them contain a frothy, fluid substance, protoplasm.
Inside this is a tiny vesicle, the nucleus. This in turn
has the same texture as the protoplasm of the sur-
rounding cell-body. Only the nucleus is enclosed by
a delicate membrane, while there is no membrane
enclosing the entire cell, at least not in most animal
specimens. Plant -cells have always a membrane,
sometimes a comparatively thick one.

Thus the principal characteristic of a cell is its
nucleus. But this is not the whole of its contents ; it
has other invariable elements besides the nucleus. The
nucleus itself is not a simple structure, but always
contains certain compact particles which are comprised
together under the name of “chromatin.” It is believed
that these contain the matter that is the vehicle of
heredity. On this view they are the most important
parts of the cell.

Thus the protoplasm of which the cell consists
contains a number of deposits, and this shows that
it is not a formless mass. It is especially the frothy
character of the protoplasm that gives it a definite
structure . 2 We know from the seventh chapter that

1 The cell was discovered in 1667 by Robert Hooke, who examined
a cork, and found that it was composed of cells like a honey-comb.
The term “cell” is still retained, though we now know that the cell is
a solid particle, and often has no membrane at all, so that it has no
resemblance to the honey-comb cell.

2 1 he theory of the frothy structure of protoplasm was advanced by
O. Butschli, and has generally displaced other theories.

290 DARWINISM AND THE PROBLEMS OF LIFE

the chemical constituents of the organic substance are
living albuminoids, the biogens. Now, we know that
this substance has a definite form, protoplasm.

Although the cells may differ widely in form and size,
the organs of animals would not be so varied as they are
if the cells could not give out different kinds of products.
Our skin and viscera consist directly of cells, but they
only form the basis of the muscles and bones.

But, it will be asked, how can the cells create
anything new ?

These elementary units of the organic body feed and
grow naturally in virtue of the nourishment circulating
in the body. However, they do not need the food
solely for their own growth and the maintenance of the
vital activity ; from one portion of it they form special
substances which they eject at their surface. Thus the
skeleton of the articulates was formed as a secretion of
the cell-layer of the underlying skin, and our bones and
muscles, also, are the secretory products of large numbers
of cells. These products have a function ; they serve
for support or movement, like the bones and muscles, or
for the conducting of stimuli, like the neural substance.
On the other hand, the cells that have produced these
substances renew and nourish them.

The great advantage of this kind of organ-construction
is in the division of labour , a principle that is also found
in civilised life, and forms its foundation. It is at work
not only in the body politic, but in every warehouse and
factory. This alone makes it possible, for instance, to
build a good house ; this can only be done if one part
of the workers looks after the building, another the

PROTOZOA

29I

wood-work, a third the locks, another the painting’, and
so on. Then each section knows its own business, and
can pursue it with effect.

The whole organisation of the higher animals rests
on the principle of the division of labour. If each cell
had to discharge all the vital functions, they would
restrict each other. The secretory product only dis-
charges one function, and so is not distracted by other
duties in doing so.

The lower we descend in the animal scale, the less
division of labour do we find. Thus, in the animals
with which we concluded the preceding chapter, the
polyps, we find only two kinds of cells — as a rule, at
least — which clothe the inner and outer surfaces of the
sac-shaped body. The internal layer of cells accom-
plishes digestion ; the external keeps the animal in
touch with the outer world. Both of them are equally
engaged in movement. In the further course of animal
evolution the external stratum of cells was differentiated
into skin and nerves ; the internal divided into the
alimentary canal, with its dependent glands, and the
muscles and bones.

In harmony with the theory of descent we must
assume that in certain ancestors of the polyps there
was as yet no division of labour ; that each cell had
to discharge every function. And these mulberry-
shaped animals must in turn have had ancestors that
consisted of a single cell.

The embryonic development of every animal establishes
some such series of ancestors. Every animal begins
life as a single cell, the ovum. To this succeeds a

292

DARWINISM AND THE PROBLEMS OF LIFE

homogeneous cluster of cells ; and from this is
developed the polyp stage, consisting of two layers of
cells. The development then continues its course.

Geology can tell us nothing about the first living
things. Apart from the fact that they must have
appeared at a time of which no evidence has been
handed down to us, they may have had no hard parts,
and so could not possibly be fossilised.

But may not these lowest animals have survived to
our own time, without having abandoned their unicellular
character ? As a matter of fact, there are not only
polyps to - day, but there are millions of minute
organisms in every drop of water that consist of a
single cell. These are the protozoa .

Since the whole body of the protozoa is a single cell,
it cannot be large, nor have different organs, as the
organs consist of several cells of different kinds. It is
all the more wonderful to find that natural selection has
created an infinite variety of forms among the protozoa.
There are the amoebic, small pieces of protoplasm with
a nucleus, which move about something like beer-froth
on a glass plate. If a tiny alga-granule lies in the way
of one of these animals, it moves towards it and surrounds
it, and the alga finds itself inside the amoeba. Gradually
we see a change in the alga-granule. Its digestible
parts are assimilated by the protoplasm of the amoeba,
and the indigestible remainder is thrust out at some
point.

The movement of the amoebae is merely a sort of
flow, with constant changes of its shape, but the
“flagellates” have on their cell-body one or two lashes

PROTOZOA

293

which carry the animal along swiftly by beating the
water. These, and still more the higher protozoa, the
‘‘ciliated infusoria,” need a special motor apparatus,
because their cell -body is surrounded by a delicate
membrane ; it gives more firmness to the animal, but
prevents the flowing movement of its substance. While
the flagellates have their lashes or whips, the whole
skin of the ciliated infusoria, or special parts of it, is
covered with countless hairs or “cilia,” which strike the
water in a uniform direction, like a row of oars, and
force the animal forward. Further, the clothing of
the skin of these animals prevents them from feeding
as the amoebae do, and so the infusoria have a special
opening in the skin, through which the food can enter
the protoplasm and be ejected again. Round this
aperture, especially in the sedentary vorticelke, there
are long lashes that cause a small whirlpool in the
water and so bring the food down into the animal.
Naturally, unwelcome foreign bodies are often brought
into it in this way, and have to be ejected again.

Thus we see that the single cell is capable of very
different adaptations, and so we cannot be surprised if
the cells that compose the higher animals assume such
enormously different forms. But while the cells of the
latter are usually selected only in one direction, the cell
of the protozoa has to advance in every possible direc-
tion. In the protozoa the one cell discharges all the
vital functions, locomotion, nutrition, respiration, and
reproduction.

1 he latter function is accomplished in a very simple
way in the unicellulars. Let us take the amoeba, for

294 DARWINISM AND THE PROBLEMS OF LIFE

instance. The particle of protoplasm that constitutes
the animal contracts from two opposite sides. It
becomes thinner and thinner in the middle, until the
cord that has kept the two halves together gives way.
During the division the nucleus also has been drawn
out and constricted, so that when two animals are found
instead of the one, each of them has a half of the
nucleus. The two pieces of the amoeba then quickly
feed themselves up to the normal size of the species,
and each half of the nucleus attains the size of the
whole one. The essence of reproduction is the same
in all the protozoa : the animal splits into two halves,
and thus the “mother” divides into two “daughters.”

The cells of the higher animals multiply in the same
way as the protozoa. The only difference is that in
their case the cells remain united after the cleavage,
whereas in the protozoa they become independent, and
go their own ways. Hence the development of a multi-
cellular animal is as follows. The ovum, which always
consists of one cell, divides into two daughter-cells ;
these again divide into two, and thus four are produced.
After the next cleavage there are eight, then sixteen
cells, and so on, until we have a compact cluster of
cells. The cells then arrange themselves ; they lay
themselves in two strata, and form a sac. Thus they
reach the polyp stage, and the differentiation continues.
Some of the cells secrete muscular matter, others the
skeletal matter, until the whole complicated animal is
constructed.

What a wonderful development ! How is it possible
that from this repeated cleavage we get, not an irregular

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295

cluster of homogeneous cells, but a harmonious whole,
the very different parts of which always come to lie at
the right spot ? We must admit the impotence of science
in face of these embryonic mysteries. We know nothing
of the forces at work here ; but we can say with some
confidence that no supernatural power controls the
development of an animal, so that each separate process
shall bring it a step nearer the complete construction.
The co-operation of the parts has clearly been brought
to its present height by natural selection, and the forces
at work in embryonic development are certainly not
different from those that we know in organic nature as
attraction and repulsion, strain and release.

We saw in the sixth chapter that there are in the
ovum minute particles that represent the rudiments of
the future organs. We may now add that it has been
claimed that these particles are the chromatin that is
found in the nucleus of every cell, and so of the ovum,
in the shape of a number of minute corpuscles . 1 We
know that this chromatin also divides in the cleavage
of the cell, and this is done by so fine a piece of
mechanism that one daughter-nucleus receives jzist as
many halves of the particles as the other. If this
substance represents the rudiments of the future organs,
as we have good reason to believe, the ontogeny of an
animal would run somewhat as follows. In the first,

1 We know from the following experience that the nucleus is the
chief constituent of the cell. It has been proved experimentally that
in protozoa that were cut into pieees, only those parts remained alive
and grew into fresh animals which contained a fragment of the nucleus.
Pieces without nucleus died ; even pieces of an amoeba without nucleus
could not creep along, but floated about aimlessly in the water.

296 DARWINISM AND THE PROBLEMS OF LIFE

and generally in a few of the further, cleavages of the
ovum the halves of all the rudimentary parts pass into
each daughter-cell, and they complete each other, so
that the first segmentation-cells have still the power of
constructing the whole organism, because they have the
rudiments of all the organs. But in the further course
of development the rudimentary parts, which have not
yet made any use of their power to form organs, enter
into action. When the number of cells is large, the
dividing cells receive all the rudimentary parts, but
these do not remain united in the nucleus of the new
cells ; some of them pass into the protoplasm of the
cells, and thus give a definite character to them. When,
for instance, the development has proceeded far enough
for the construction of the alimentary canal to have
begun, the alimentary basic parts pass out of the
nuclei and give the new cells the character of alimen-
tary cells. The cells that afterwards separate from
these are, therefore, devoid of the alimentary parts.
As they divide further, the other bases of the various
organs pass out of their nuclei ; the nerve-parts convert
certain cleavage-cells into neural cells, and so on. In a
word, the basic or rudimentary parts continue to work
until the construction of the organism is completed.
Naturally, this description of the process does not rest
on observation, but is a theory, founded by Weismann ;
but it must be admitted that it makes the embryonic
development intelligible . 1

This continuous transfer of the basic parts does not

1 The above is an outline of Weismann’s “germ-plasm theory,” the
most elaborate theory of heredity that we have.

*

PROTOZOA

29 7

affect all the cells. In the very first segmentations of
the ovum, in which none of these parts come into play,
but are equally distributed among the daughter- cells,
certain cells were separated that retained all their
rudimentary parts, and therefore the power to build
up a complete organism. These were the germ-cells .
While the great mass of the cells differentiated more
and more in the course of development, these remained
inactive, or only divided in such a way that all the
rudimentary parts were retained in their daughter-
cells. Hence the germ-cells persist through the whole
embryonic development, and only come into prominence
when it is over, and the animal is fully formed. The
inactive basic parts that they have all retained then
enable them to produce a new organism under proper
conditions.

Thus the multicellular animals multiply by means of
germ-cells. How has this method of propagation arisen
out of that of the protozoa ?

In the protozoa the single cell is also the germ-cell,
as it has to undertake all the vital functions. Every
cleavage of the unicellular being is a reproduction.

d here is a certain animal in our fresh waters called
the “pandorina.” It consists of sixteen cells, all
homogeneous, and each of them discharging all the
functions. Each of the sixteen can reproduce the
animal, by detaching itself from the cluster and sub-
dividing until it makes sixteen cells. Hence in the
pandorina each cell can act as a germ-cell. There is
no division of labour.

The next step brings us to the “volvox,” a green

298 DARWINISM AND THE PROBLEMS OF LIFE

globule about the size of a pin’s head, consisting of a
number of cells. It is often found in large quantities
in our ponds. In this animal we have the first division
of labour. Most of the cells have taken charge of the
functions of movement and nutrition ; a few others of
a different shape are responsible for reproduction.
These lie in the centre of the other cells, and can
by repeated cleavage create a new animal, which
detaches itself from the mother and swims about. If
the parent has given up all its germ-cells, it dies off,
since its other cells cannot produce germ-cells.

There does not seem to be anything more wonderful
in the reproduction of the protozoa. Two quite equal
halves are formed by cleavage, and each of them has
only to grow, not to form anything new. It is the same
with the pandorina, only in this case the cleavage is
repeated three times, and produces sixteen cells which
remain united. It is in the volvox that the marvel of
heredity first appears. Here the germ- cell reproduces
not only its kind, but also the very different cells of the
body. But there is no sudden leap from the protozoa
to the volvox. There are many protozoa in which the
fore end differs a good deal from the hind end ; and
when such an animal divides, each half must reproduce
features that it does not possess. Mere growth could
not convert fragments of these animals with different
parts into whole individuals.

We can more or less understand the mystery of
heredity with the aid of the above theory. Even the
protozoon contains rudimentary parts in its nucleus,
which can build up the different parts of the cell

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299

body. When the animal divides, each piece receives
halves of all the basic parts, and therefore those also
that can supply the part that is wanting in each half.
So it is with the pandorina. In the volvox two cells
result from the germ. One of them contains all the
rudimentary parts in a state of quiescence ; this is the
germ -cell, the rudimentary parts in which wait until
the animal is fully grown. But the other cell con-
tinues to subdivide, and as it does so the rudimentary
parts come into play, and produce the various volvox-
cells with all their peculiarities. The process is the
same in all the higher animals. There is always one
section of the cells arising from the ovum that contains
all the rudimentary parts in a state of slumber, as it
were ; these are the germ-cells. On the other hand,
the parts come into play in the body-cells, and give
distinctive characters to various groups of cells. At
the same time these cells lose the particular rudi-
mentary parts from their nuclei, and can never build
up an entire organism, as the germ-cells do . 1

We have not taken into account the fact of sextial
generation. But we said in the seventh chapter that

x This is Weismann’s theory. There are many exceptions, in which
body-cells have in their nucleus the quiescent basic parts of all the
sections of the body. We see this, for instance, in the phenomena
of regeneration. Here, if certain parts of the body are cut off, the
rudimentary parts that were quiescent in the cells of the contiguous
parts come into play, and re-build the last fragment. Plants have
rudimentary particles at all possible parts of the body, because any
sprout can reproduce a new plant. In fact, in certain plants, such as
the begonia, even the leaf-cells have these quiescent rudimentary
particles. If a begonia-leaf is set in moist soil, new plants grow
from it.

300 DARWINISM AND THE PROBLEMS OF LIFE

“ amphimixis ” has originally nothing to do with
reproduction.

This is perfectly clear in the case of the protozoa.
If we glance at the transitional forms between the
unicellulars and the multicellulars, we shall see how
“sexual” reproduction came gradually to spread.

In the unicellulars the whole animal has to unite
with another to give amphimixis. This is really what
happens. Two protozoa, apparently of the same size
and appearance, put their cell bodies together, and
coalesce into one mass. After a time they separate
again, and the process of amphimixis is over. Here
we see clearly that amphimixis does not aim at
multiplication in its original form, because there are
two animals both before and after it.

Do the protozoa confirm the view we adopted in
the seventh chapter that it is the object of amphimixis
to give the new organism a choice of the character-
istics of two “ parents,” so as to make it more
capable of different adaptations ? That is really the
case. The various characteristics of an animal’s frame
are based on the rudimentary particles of the germ ;
in the case of the protozoa, in which body and germ
are one, this means in the nucleus of the cell. Now
it has been noticed that during the conjunction of two
protozoa the nucleus of one of them divides, and
transfers one half to the body of its companion, where
it blends with the half that has remained there.
Hence when the animals separate once more, the
nucleus of each contains a half of the rudimentary
particles of the other protozoon as well as half of

PROTOZOA

3 QI

its own. These particles are, therefore, mixed and
combined afresh through the amphimixis.

Moreover, the protozoa have two nuclei. It is only
the smaller of these that contains the rudimentary
particles and mixes them in the manner described.
The larger one has only the function of attending to the
animal’s nutrition, movement and respiration. During
the amphimixis it dissolves, and is afterwards recon-
structed by the small nucleus.

As a rule there is a cleavage, and therefore a multi-
plication, of the protozoa that have separated after the
conjunction has been completed. But the chief method
of reproduction amongst them is non-sexual, that is to
say, cleavage without amphimixis. In the multicellular
animals amphimixis is always followed by multiplication.
How could the germ-cells, the only ones that can enter
into amphimixis in such cases, return to the bodies of
their bearers after the act ! If the amphimixis is to
have any result, two germ-cells must leave the parent
bodies, combine, and produce directly a new animal,
which will have the united rudimentary particles.

This is how the process of amphimixis takes place in
the pandorina, which has no division of body and germ-
cells. Any cell in the cluster may in this case detach
itself, combine with another that has separated from
some other animal, and with it build up a new animal.
Reproduction after amphimixis is only occasional in the
pandorina ; as a rule it multiplies sexually, as stated
above.

How does the process take place in the volvox, in
which there are two different kinds of cells, body and

302 DARWINISM AND THE PROBLEMS OF LIFE

germ-cells ? In this case, naturally, the germ-cells
alone enter into amphimixis. The division of labour
has advanced so far in the volvox that the germ-cells
which reproduce the animal in the non-sexual way
we have described cannot enter into amphimixis. A
different kind of germ-cells has been provided for this ;
these also are found in the cell cluster of the volvox, but
they are only formed from time to time. In fact, there
has been a division of labour even amongst these sexual
germ-cells. There are two kinds of them produced in
the same animal, so that at the proper moment a volvox
has four sorts of cells — body-cells, asexual germ-cells,
and two kinds of sexual germ-cells.

One of the lattet kinds is comparatively large, and is
only formed in small numbers ; and they resemble the
asexual germ-cells. The cells of the other kind lie in
packets, each containing several, in the volvox body.
These cells are very small and have mobile lashes, like
the body-cells. They break away, when they are
mature, and seek another volvox, and combine with its
sexual germ-cells of the first kind. The product of the
fusion then dissolves, and develops into a new animal.

In the volvox we have the same features that we find,
essentially, in all the higher animals. In these, how-
ever, the asexual germ-cells have generally disappeared ;
they are common only in the plants, in the shape of
spores. With the disappearance of the asexual germ-
cells the animal is now reduced to one method of
reproduction, that following upon amphimixis. Never-
theless, the cases of parthenogenesis show that natural
selection can impart even to the sexual germ-cell, the

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303

whole structure of which is framed so as only to divide
and develop after amphimixis, the power of developing
without union. Apart from these the importance of
amphimixis led to the disappearance of the asexual
germ-cells, and the animals were forced to effect
amphimixis if they wished to multiply.

It will have already occurred to the reader that the
inactive sexual germ-cells of the volvox correspond to
the ova of the higher animals, and the active germ-cells
to the spermatozoa ; even in man the latter have retained
the lashes of their flagellate period. But, whereas in
the volvox the same individual produces both kinds of
germ-cells, as is the case with many other animals, which
we call hermaphrodites, we find most animals divided
into male and female, each with only one kind of germ-
cells. These are matured at special parts of the body,
namely, in the ovaries or testicles, as the case may be.
They have diverged more and more from each other in
structure. In this the chief principle was the division of
labour. The germ-cells had to find each other, and had
to provide a certain amount of nourishment for the
development of the young after combining. The first
function devolved on the spermatozoa, which are
endowed with mobility according to the requirements of
each species. As a rule they are equipped with mobile
lashes, and are produced in enormous quantities, which
is facilitated by their smallness. They can be small,
because they do not need to contribute any nourishment
for the new organism, but only the paternal characters
that are found in their nucleus. The food is provided
by the ovum, and so this may attain considerable

304 DARWINISM AND THE PROBLEMS OF LIFE

size. The yellow of the hen’s egg, for instance, is at
first a single cell while it is still inside the hen. The
nucleus of this cell is small, but the cell body takes up
an immense amount of yolk, and then the whole is
surrounded by the white and the shell ; these are later
products, superadded to the yellow. When the egg is
laid, it is, of course, fertilised, and there have already
been a number of cell cleavages, so that the white dot
on the yellow yolk, the “ scar ” as it is called, is really
a somewhat advanced embryo.

Continuous adaptation has brought about great differ-
ences in the form of the spermatozoon and ovum in the
various animals. It is obvious that those animals will
always be favoured by selection whose germ-cells were
the surest to find each other ; animals whose sperma-
tozoa, for instance, were not active enough to reach the
female ova could not reproduce, and their sluggish
sperm-cells would die with them. Thus we can under-
stand why in the case of organisms that eject their seed
into water, it is produced in large quantities and is very
mobile. In these cases it is largely a matter of chance
whether a single spermatozoon will find its ovum.
When it does reach one, the physico-chemical nature
of the two cells attracts them to each other and fuses
them together. Even then it is no light task for the
mammal spermatozoa to pass up the oviducts to the
ovum in the ovary, and this explains their number and
activity.

However, I have not space to deal with either the
great diversity of form in the animal ova and sperm-
cells or the interesting relation in which we always find

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305

them to the life of the particular species. Their admir-
able adaptations are easily understood. They are the
maintainers of the species ; in a sense they are its most
essential element. If we recall our account of the
embryonic development, it is clear that the germ-cells
of living animals must have existed, in a sense, since
the beginning of life. The germ-cells are never created
afresh ; they are always formed by segmentation from
the germ-cells of the parents. Let us, for a moment,
ignore the fact that there are two kinds of germ-cells,
and consider the process of phylogeny (or ancestral
development) in the case of an organism that has only
one kind of germ-cells. These cells contain the basic
particles of a new organism. They divide and sub-
divide. One portion of the cells again receives all the
basic particles, the other portion only a part of them,
and this grows less and less as the cleavage proceeds,
because the organs are gradually formed. The cells of
the various organs cannot give birth to an entire organ-
ism, because they contain only a few of the basic
particles ; they have the most diverse functions, and
afterwards die off. Not so the germ-cells. These form
a chain that may be infinite in length. They perish, of
course, if the animal they are in perishes, and they can
also be destroyed by poison like all living matter ; but
under the proper conditions they go on to build up a
new organism, and so on. Hence they have been com-
pared to a root stretching under the ground, that brings
forth plants above the surface under certain circum-
stances and at certain times. These plants grow and

perish, but the root remains ; it grows on and on, and

u

3° 6 DARWINISM AND THE PROBLEMS OF LIFE

thus constitutes the persistent ground-work of the
changing forms of life.

Hence the germ-cells are the main trunk of the
organic world. In them are contained the basic par-
ticles ; and as these vary they give birth to ever-new
forms of life. If the new variation is useful in the
struggle for life, the animal is preserved, and with it
the germ-cells. These produce their kind, in unbroken
continuity, and so continue their life - creating action.
It is the germ-cells that vary of themselves , and so
determine the whole variability of organisms. The
body-cells cannot affect them ; they merely represent
the house which, by its superiority or inferiority of
structure (which, however, it owes to the germ-cells),
enables them to continue their course, or suffers them
to be cut off 1

As each germ-cell forms another germ-cell, together
with the organism, this does the same, and the process
may go on indefinitely, there seems to be something
immortal in the germ-cell. How is it with the protozoa?
In these the body and the germ are one ; the germ-cell

1 There is a novel of Grant Allen’s, “A Terrible Inheritance,” in
which a young man suddenly remembers certain details in the life of
his mother before marriage, and the youthful escapades of his father,
without having been told anything about them. The story is, to some
extent, an attempt at a practical application of the Lamarckian prin-
ciple, and really amounts to a reductio ad absurdum of it. While the
youth was merely a germ-cell in the mother’s ovary — and in the father
— she is supposed to have suffered a powerful emotion that was deeply
imprinted on her. The germ-cell is supposed to have been influenced
in the same way. The cell shared the experience in a sense, and its
memory-elements are supposed to have been so acted upon that when
the cell became a human being, he could recall the conduct of the
mother.

PROTOZOA

307

does not build up a temporary body-shell, but only germ-
cells. These are, of course, bodies, but there is nothing
temporary formed from them ; they in turn create only
cells that have the power to live on. Every protozoon
multiplies by dividing into two. If dangers are avoided,
these animals will continue to live, divide into others,
and so on ; in a word, it is possible that one of these
animals may never become a corpse. The protozoa
seem to have, as Weismann puts it, a potential
immortality ; that is to say, they have in their frame
a capacity for living indefinitely. This is, of course,
only a capacity. No one questions that they may come
to a violent end. But it is not in the nature of their
structure that they are menaced with senile decay and
death, and that life itself gradually uses up their sub-
stance, as is the case with the body-cells of the higher
animals.

It has been objected to this view, that the protozoa
have no natural death, that at each cleavage the indi-
viduality of the mother comes to an end. “ Individual ”
means “indivisible,” and it is clear that the mother dies
when it divides into two daughters, as these are two new
individuals.

Weismann, however, considers that the characteristic
of death is not the destruction of individuality, but the
appearance of a corpse. We will not stay to discuss
whether this conception is correct, but will go to the
heart of the problem. The protozoa have, Weismann
says, the faculty of not being permanently used up by
metabolism, and this can be called metaphorically, with
some propriety, immortality. But is there really in the

308 DARWINISM AND THE PROBLEMS OF LIFE

protozoa nothing that ever compels them to become
corpses ? This seems to be correct. There can be no
such necessity in the protozoa, otherwise there would be
no protozoa to-day that are fragments of their ancestors,
though the parts have fully developed in turn. When
a protozoon is split into two daughters there is certainly
no corpse to be seen, and it is the same when the
daughters in turn subdivide. Here we have a difference
between unicellulars and multicellulars. In the latter
it is only the small particles in the germ-cells that are
immortal. The germs divide. But only one part, the
newly divided germ-cells, have the power to carry on
the life. The other part, the body-cells, are used up
by metabolism, and must perish. The unicellulars
divide, but in their case both halves can carry on the
life indefinitely.

Natural death is not, therefore, a necessity for all
organisms, but has only made its appearance with the
multicellulars. In their case the germ-cells convey the
living substance to their descendants ; when they leave
the body, it is useless for the maintenance of the species,
as it has not the power to create new organisms.
Weismann believes that we have here the chief
reason of the introduction of death into the organic
world. The body becomes superfluous and disappears,
like all useless organisms, when it has secured the
maintenance of the species by the transmission of its
germ-cells. However that may be, we see that the
division of labour amongst the several groups of body-
cells could not be very considerable unless they made
no claim to indefinite duration. Many cells, in fact, have

PROTOZOA 3°9

precisely the duty of dissolving themselves ; and it is
possible that most cells only do their work so well at
the cost of using themselves up in the process. They
can do this, because the propagation of the species is
secured by the germ - cells, which perform their duty
the more confidently when the body they are in is in a
good condition. The more advanced the body is in
organisation, the better will be the nutrition of the germ
apd the greater its security from dangers.

It may be asked whether there is not some such division
of labour within the one cell of the protozoa ; whether
there are not in these animals also parts that can only
discharge their function for a certain time, and must then
decay and be reconstructed by the permanent parts of
the cell.

This is really the case. In many of the protozoa only
the nucleus and a small part of the protoplasm are
divided in non-sexual multiplication, for the greater part
of the cell-body dies. Hence there are a number of
protozoa in which we constantly find dead parts. In
fact, it looks as if dead parts are continually being
extruded from all protozoa. It has been proved by
careful experiments that protozoa perish if they are
impeded in their amphimixis. Thus amphimixis is
necessary for the protozoa . 1 It is true that they usually
propagate asexually, but from time to time their body has
to effect an exchange of basic particles with another one.

1 I cannot go any further here into the introduction of amphimixis
into the organic world. Weismann has attempted to trace it to its
ultimate roots. He believes that it arose in the earliest, unnucleated
living things, and had a favourable influence on their metabolism. It
was, therefore, a process of adaptation.

310 DARWINISM AND THE PROBLEMS OF LIFE

But if any protozoa must submit to amphimixis in
order to preserve the species, there are in the group
parts that are subject to natural death. We have
described above how in the amphimixis of the unicellulars
the large nucleus, which undertakes the vital functions,
dissolves, and thus represents the corpse. It does not
alter the case essentially that this corpse is small in pro-
portion to the animal ; in many of the higher animals
the germ-cells are much larger than the body — as in the
case of the frog’s eggs. The question is whether there
are any animals whose whole substance lives on con-
tinuously and is not dissolved by its metabolism.
That is clearly not the case with the protozoa. We are,
therefore, not justified in drawing a line between the
unicellulars and multicellulars, and saying that the former
are immortal and the latter not.

However, the protozoa are not the lowest organisms.
In them the living matter is already differentiated,
particularly into nucleus and cell-body. In our view
there must have been animals from the beginning of
life in which there was no differentiation. It is a
question whether there are now any unnucleated
organisms of this kind, as a nucleus has been found
even in the smallest animals. That is, of course, not
conclusive, because the simplest living things may be
below the limit of visibility. However that may be, we
can at least picture to ourselves animals whose repro-
duction consists merely in dividing without leaving any
residue, and in which there is not any amphimixis.
We must not forget, of course, that even in such
animals the living matter as such is not immortal,

PROTOZOA

3 ii

since it is its property to be always breaking
up.

There cannot, therefore, be any living thing of which
the substance, as such, is lifted above time. Yet we
speak of immortality, because there is a continuity of
life. Our own body is breaking up constantly through-
out life, yet we do not speak of this as death ; in fact,
we hardly perceive the constant process.

In the seventh chapter we dealt with the activity of
the living matter, of the biogens. These have to break
up, it is true, but they have the power to build up one or
more new biogens before they die, and this secures a
continuity of the life. We can picture to ourselves the
activity of the biogens, in the growth and decay of an
organisation, in something like the following way. At
first they create several of their kind before they break
up, and thus effect the growth of the animal. Then
each produces only one biogen, and thus they maintain
the organism at its height. Finally, they are unable to
make any new biogens before they decay, and so they
bring about the death of the organism.

Life can only continue to exist because there are
biogens the action of which is never paralysed in all
their generations. There are biogens that can maintain
life in continuity, and so bring about an immortality of
life. But in the multicellulars and unicellulars this can
only be done permanently by some of the biogens ; by
the others it can only be done to a certain point — until
death. We can, however, conceive living things of the
simplest character, the bodies of which consist entirely
of such biogens. These animals might not improperly

312 DARWINISM AND THE PROBLEMS OF LIFE

be called immortal, because no part of their body
perishes without providing a substitute ; in other words,
no part forms a corpse.

We know too little of the biogens and their activity
to be able to say why all biogens are not indefatigable
in creating a substitute. It has been suggested that the
temporary biogens can only achieve this by drawing on
their own energy. They differ so much in the structure
of their elements that some irregularity is unavoidable
in the co-operation of the various parts. In the course
of their life these irregularities increase, and at last a
time must come when the biogens are shaken to the
foundations of their structure. They then break up.
That is the meaning of death.

We are led to conclude, then, that the introduction of
death into the world was useful, because the living
matter was bound to give up all claim to eternal con-
tinuity before it could be so differentiated that its
possessor could escape violent death. However, some
of the biogens had to retain the power of continuous
creation, in order to maintain life upon the earth.

Just as death was introduced by natural selection, so
the moment of its occurrence is carefully regulated. In
each animal species natural death only sets in when the
maintenance of the species is secured. The duration
of life is strictly proportioned in all organisms to their
reproductive powers. But I have not space to discuss
this in detail here.

Life will not continue for ever on the earth. A time
will come when the earth will course through space,
a frozen mass, and a violent end will come to all

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organisms . 1 The moon already shows us what the
fate of our planet will be. And as the earth will
necessarily change until it becomes incapable of sup-
porting organic life, so there must have been a moment
in its past development when no plant or animal could
be found on it. In this case it was the glowing heat —
in the former the icy cold — that precluded the presence
of life. Neither extreme can be borne by life; it can
only maintain itself between the two poles, and will
perish if one of them approaches nearer. We may
now ask when life made its appearance, and whence
it came.

We saw that the living substance is continually being
built up out of inorganic matter, but that this can only
be effected by living matter already in existence. If
we go far back in the history of the earth we come to
a point when it was a molten mass and could not
possibly contain life. Whence did this come, then ?
It might be possible for life to be conveyed from some
other body to the earth after it had cooled down. A
few scientists have suggested this , 2 supposing that it
may have been brought to the earth by meteorites.
It has been replied to them that delicate organisms
could hardly endure the icy cold of space, and then
the incandescent heat of the meteor as it passes through
the earth’s atmosphere. The objection is not entirely
sound. Particles of charcoal and soil have often been

1 Verworn urges this as a difficulty against Weismann, but he is
clearly wrong. The cooling of the earth causes a violent death, and
is not inconsistent with potential immortality, or a capacity for enduring
life. T his naturally presupposes external conditions.

2 Lord Kelvin, Richter, and Helmholtz.

3H DARWINISM AND THE PROBLEMS OF LIFE

found inside meteorites, and if these could stand the
heat we may grant that also of the living substance.
Nor is the fact that the meteorites provide no food or
water a reason for denying- that they might contain
life. Grains of seed can remain a long time without
water or food.

It has also been said that this “cosmozoic theory”
does not answer the question of the origin of life, but
only postpones it. If we put life off to another planet,
we have to ask how it was born there.

But this also is wrong. It might be said that life
was not born on that other planet, but brought from a
third one. In a word, it might be said that the living
substance has existed from all eternity, like matter and
motion. This theory, that life had no beginning, that
it is eternal, gives an answer to the question.

But there are more effective objections to the
cosmozoic theory. In the first place, we see that the
plants build up living matter from inorganic matter
every day. If the living substance can thus be created
daily, it cannot be eternal. Still less will we believe in
the eternity of the organic substance if we reflect that
organisms can perish. An eternal matter ought to
be imperishable. Inorganic matter, which is eternal,
cannot be entirely destroyed. It changes — we can
do what we will with it — into another form of inorganic
matter, but this also is eternal. It is otherwise with
living matter. This can be destroyed as living matter ;
it does not then change into another form of living
matter, but into inorganic matter.

As we see every day with our own eyes how living

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substance is formed from lifeless, and changes back
into it, we may assume that it had its first origin in
inorganic matter. We have the more right to do this
since no element has yet been found in living matter
that is not found in the inorganic world. There is no
essential difference between the albuminoids and other
compounds. Finally, we know that all compounds are
made up of simple elements. The whole of science
is based on this fact. It would be contrary to all
experience if compounds suddenly appeared that were
not formed from others, but had existed for all
eternity without any connection with nature, as it
were . 1

We are thus driven, by a number of considerations,
to the conclusion that life was born on our planet. And
as there can only have been inorganic matter on our
planet from the first, life must have been evolved from
it; nothing can be made out of nothing. It is no
objection against our theory that we have not
yet succeeded in artificially producing living matter or
animals. How could we hope to do this when we know
neither the structure of living albumen nor the forces
that create it. The fact that no living matter has yet
been produced artificially only shows that a certain

1 There is still another important theory of the origin of life, that
of Preyer. This takes the idea of life in a wider sense than we
usually do. It regards the molten planet as a living organism,
and so postulates a continuity of life. In the form to which we
now give the name of living matter, Preyer himself admits that
it was formed by spontaneous generation. It is a question whether
we should be justified in speaking of the movement of inorganic
masses as life. It is a question of terms, and we will not enlarge
on it.

316 DARWINISM AND THE- PROBLEMS OF LIFE

experiment has failed ; it does not show that there may
not be other unknown methods by which living albumen
can be constructed. In a word, we can quite understand
the failure of all the attempts made up to the present to
create living matter, because in the actual condition of
our knowledge of life they are merely shots in the
dark.

It is possible, in fact, that life could only be formed
on our planet when it was at a certain stage of
development that has long since passed away. The
distinguished physiologist Pfliiger has formulated and
firmly established a theory in that sense. He
believes that the first steps towards life could only be
taken when the earth was still entirely or partially in a
molten condition. This would be a justification of the
old saying that life was born from fire.

I cannot, unfortunately, go into Pfluger’s theory at
any length, as it requires a thorough knowlege of
chemistry. I will merely give a general outline
of it.

There are certain elaborate compounds, known as
“cyanic compounds,” which are easily broken up, and
have a good deal of analogy with living matter. These
compounds are only formed at an incandescent heat.
They may, therefore, have been formed when the earth
was still incandescent at its surface. In consequence of
their decomposibility they soon entered into relations
with other compounds. And when the steam descended
on the earth, and the masses of water began to form, the
cyanic compounds combined with the fluid element and
the salts dissolved in it, and thus gave rise to the living

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albuminoids. Tiiese were very simple at first, and not
yet differentiated into cells ; but they had from the
beginning the faculty of metabolism.

Thus the origin of life was determined by the condi-
tion of the earth. The living substance is part of the
matter of the earth, and has been formed therefrom by
spontaneous generation. It was just as necessary an
evolution as that of the rocks, when the conditions of it
were given. Throughout the whole universe there is
an endless chain of causes and effects, and the origin of
life comes within this inexorable chain. The further
development of the living substance and the moulding
of it into the more advanced plants and animals was
another necessary consequence of the condition of the
earth at the time. These transformations were effects
of causes that in turn sprang from other causes. We
have long known that all that happens in organic nature
is determined by necessary, endless chains of cause
and effect. It is the immortal merit of Darwin to
have brought life also within this series.

We may now picture to ourselves the first development
of life. We begin with the living substance, the origin
of which we have outlined above. In the beginning
were the biogens. These must be conceived in the
form of living things with a metabolism like that of the
actual plant. Their constant break-up would have led
to the destruction of all life if they had not had the
power of creating their like out of inorganic matter.
I hey cannot, of course, have had any chlorophyll, the
green substance that effects the construction of organic
matter from inorganic in most of our actual plants.

3l8 DARWINISM AND THE PROBLEMS OF LIFE

Chlorophyll is much too complex a structure for us to
suppose it to have been present from the first. No,
these biogens were clearly like the actual nitrogenous
bacteria, very simple organisms, that can convert lifeless
into living matter.

The next step in the development of life was that the
biogens, which were at first quite homogeneous, clustered
together like stars. External conditions were acting
constantly on all these primitive beings, because it is
the nature of the living substance to be flexible and
modifiable. We can thus understand that the activity
of the biogens, in creating their like before they broke
up, would be greater in warm and well-lit places than in
less favourable ones. Here we have the first cause of
differentiation. If we further remember the great diver-
sity of the earth’s surface, we can see that this of itself
would lead to a considerable variety among the living
things, since each locality would have a different effect
on the changeable living matter. Thus the Lamarckian
principle was active at the beginning of biological
evolution. Even when a group of biogens divided
and formed two, the halves retained the modifications
that had been imprinted on the parent by external
conditions.

But it would be otherwise when a differentiation set
in among the biogens in a given group. The moment
a favourable division of labour was introduced amongst
them, the organism would be in a better position, and
would be picked out by natural selection. By this
division of labour one biogen would be better able to
discharge one vital function, a second another one, and

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so on. The advance of this division of labour was more
and more favoured, and at length the organism was so
much differentiated that when it divided it gave rise,
not to two homogeneous halves, which could at once
become complete organisms in turn, but to two different
halves, each of which, in order to form the parts
wanting in it, and found in the other half, needed a
sort of depot, in which were found the biogens that
could create the half that was wanting. This store is
the nucleus of the cell ; in this are the basic particles of
each section, and thus we come to the stage of cellular
animals.

As from this stage the missing parts were formed by
the basic particles at cleavage, which were contained in
the halved nucleus, the Lamarckian principle ceased to
act. However much the protoplasm of a protozoon is
modified, the daughter-cells do not receive any part of
the modified substance at cleavage ; it is the basic
particles that build up the protoplastic parts as it grows
into the mature animal. And if the protoplastic parts
are formed afresh at each segmentation by the basic
particles, they can only change when there is a change of
the latter. But we have seen that the basic particles
change of themselves, and are not modified by bodily
stimuli.

The basic particles consist of living matter, and so
can change, grow and divide. In the earliest nucleated
organisms there can only have been a few of them, and
when changes occurred in them by chance, they created
different organisms. Let us take the case of a simple
protozoon with a cell-body containing four different

320 DARWINISM AND THE PROBLEMS OF LIFE

parts. On our theory there were four basic particles in
the nucleus of this animal, and these would form the
four protoplastic sections. Now, if one of these four
particles divided into two, and the one resulting particle
differed somewhat from the other, we should have five
basic particles ; and in the next protozoic cleavage we
should have protozoa with cell-bodies containing five
different parts.

We can conceive in this way that the multiplication
and differentiation of the basic particles would give rise
to more and more complex organisms right up to the
vertebrates. The root of the variations is, therefore,
in the basic particles. The more complex their com-
position becomes, the more highly differentiated will be
the organism whose organs they construct during the
embryonic development. But we can say nothing very
confidently as to the causes of their alteration and
multiplication. Weismann, to whom we owe the whole
of this theory of heredity, believes that the food that
must be supplied to them, as to all organic substance,
whether in the nucleus of the ovum or of the protozoon,
may vary in quantity from some accident or other, and
that a basic particle changes, multiplies, or disappears,
according to this variation in its supply of nourishment.
With it must vary the section of the body that it
builds up.

Thus the basic particles are never created afresh, but
are always formed from pre-existing ones. When they
have constructed an organism, their variations come to
light in it and in the struggle for life, because the form
of the particular organism is changed in harmony with

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their change. It is then settled whether the variation is
to survive or not. If it is of such a character that the
organism can sustain the struggle for life, it is preserved
and transmitted to offspring ; if not, the animal
perishes, and with it disappear the variations of its
basic particles. Thus in the course of time those
of the innumerable variations of the basic particles
will survive that prove useful in the developed
organism.

There is only one more reflection to make. What is
the conduct of the basic particles during amphimixis ?
As the ovum contains the basic particles of the mother
and her ancestors, and the spermatozoon those of the
father and his ancestors, the number of them must be
doubled when they unite. It will be fourfold at the
next amphimixis, and so on, until at last they fill the
cell-nucleus in immense numbers. We saw in the
seventh chapter that there are several basic particles
in the ovum for each organ, and that both the ovum and
the spermatozoon are capable of constructing several
different beings. We saw further that there is a force
which, in a way unknown to us, always selects the one
basic particle of each organ that is to build up the
particular organ. But even if this force prevents the
doubling or tripling of an organ in the developing body,
nevertheless the basic particles must increase so much
in a few generations by the eternal doubling at
amphimixis that there will at last be no room for them
in the nucleus.

To fix a limit to this indefinite increase of the basic
particles there must be some arrangement of the germ-

32 2 DARWINISM AND THE PROBLEMS OF LIFE

cells . 1 Both the ovum and the spermatozoon must pass
through a maturing process before union, the essential
point of which is that it reduces the basic particles by
one half. In the ovum and spermatozoon before union
half of the basic particles are expelled from the cell, so
that when the fusion has taken place, there is only the
normal number, and this is preserved in the same way
at each successive amphimixis. If we suppose that a
male cell contains ten basic particles and the corre-
sponding female cell the same number, amphimixis
would produce twenty, the next fusion forty, and
so on, if there were nothing to prevent the in-
crease. But as five particles have been eliminated
from the spermatozoon and ovum respectively before
amphimixis, they remain ten in number after
union. The same process has been observed in the
protozoa.

We have now formed some idea of the origin and
evolution of life. We have seen that certain biogens
in a continuous series have the power of producing
other biogens before they break up, so that the
continuity of life is maintained. Whether this power
is really lifted above time, or whether the living
substance, which had a beginning, will also of its
own nature have an end, in the sense that in the end
— though after an incalculable period — even the

1 Weismann pointed out the well-known reduction cleavage of the
ovum of this character. He postulated the same process for the
sperm-cell, because in his opinion the basic particles must be reduced
by half in this also before amphimixis. His theory was soon verified,
and the reduction cleavage of the spermatozoon was discovered.

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strongest biogens will age, and thus bring life to a
natural termination, we do not know. But we can
affirm with some confidence that one day a violent
death will make an end of all terrestrial life. The
cooling of our planet is proceeding with inexorable
necessity, and the day will come when the warm
earth of our time will course through space as a cold
and waterless sphere. All life will perish in this
state of icy rigidity.

CHAPTER X

EXTENSIONS OF THE THEORY OF SELECTION AND
OTHER EVOLUTIONARY THEORIES

Why there are numerous species to-day. Isolation facilitates the
divergence of species. Modification of isolated animals. Move-
ment and alteration of animals. Are species formed by isolation
even without the aid of natural selection? Definite variations.
Germinal selection. Changes in the nutrition of the embryo are
the foundation of variations. Do useless organs disappear through
germinal selection? Refutation of germinal selection. Effect
of external influences as modifying principle. Orthogenesis.
Rejection of same. The mutation theory. Variations and
mutations. Do variations proceed indefinitely? Is there a
formative energy in organisms? Mechanicism and vitalism.
How are the form and purposiveness of organisms explained?
What is to be understood by chance. Absence of purpose in
living things. The will to live, the instinct of self-preservation.

We can now picture to ourselves how life began on
our planet, and how it has been evolved. In virtue
of the fundamental property of organic substance,
variability, a process of transformation has been
possible that maintained organisms even amid the
changing conditions of the surface of the earth. We
recognised natural selection as the power that
continuously adapted living things to their new
environment. And as we came to the conclusion
that organisms arose entirely, or at least mainly, from
adaptations, we are bound to say that selection alone

has done all the work of transforming life.

3 2 4

EXTENSION OF EVOLUTIONARY THEORIES 325

However, we saw at an early stage that the theory
of selection will not explain everything in the present
condition of science. It could not satisfactorily
explain the various characters that are peculiar to
one sex. The auxiliary principle, sexual selection,
which we called to our aid, was so unsatisfactory that
we sought to reduce it again to natural selection. We
also failed to explain many of the rudimentary organs
because we had to reject, on the strength of
Weismann’s objections, the Lamarckian principle
that might have shed light on them. On the other
hand, when we came to the question why there are
sharply distinct species, we discovered an agency
that really solved the problem — amphimixis.

However, there seemed to be other difficulties in
the way of amphimixis. The origin of one species
from another — in other words, the divergence of
species — seemed to be inconsistent with it. How
can a new property, even when it only arises amongst
one section of a species, maintain itself and lead to
the founding of a new species, if the differently
constituted individuals are always crossing with the
modified ones ? The new feature ought to be
absorbed by the majority in this general crossing.

But we have had frequent occasion to remind the
reader of a power that can prevent crossing, and so
maintain the incipient specific character. This agency
is isolation. We will now deal with the importance
of isolation in the formation of species, to which
attention was first drawn by Moritz Wagner.

The most common effect of isolation is that a

326 DARWINISM AND THE PROBLEMS OF LIFE

number of animals are separated spatially from the
great mass of their fellows, so that there can be no
further crossing. If these isolated animals come into
a different environment, selection will modify them in
a different direction from that taken by their distant
fellows. Remember the origin of land vertebrates.
As the fishes dispersed, passed up the rivers, and
reached their higher waters, some of them may have
swum into a piece of water that was not usually
connected with the rivers. When the water fell once
more, the wanderers were cut off from their species.
Selection had another effect in their new home. In
the hot season most of the water dried up, and this
was the occasion of the conversion of the swimming
bladder into lungs.

It must have happened very frequently during the
millions of years of the earth’s history that wandering
animals were cut off from their fellows. In this way
floods and evaporation must have given occasion over
and over again to the formation of new species of
aquatic animals. Land-animals also must have been
separated by inundations. Suppose, for instance, that
the overflow of the Rhine into a certain valley killed
all the deer in it, and only left survivors on the
mountains at each side. When the water subsides
again, the deer will remain in their separate localities,
because we know that they keep always to a rather
restricted area, and do not willingly leave it. Gradu-
ally, the increase of the animals on the mountains will
bring some of them down into the valley once more.
But if they had a different environment on one range

EXTENSION OF EVOLUTIONARY THEORIES Z 2 7

of mountains from on the other, each species will have
been changed by natural selection, possibly so much that
they can no longer be crossed, or not with any effect.
Thus there will be two different species of deer in this
Rhine valley.

Inundations will often cover a large area, and this
must have happened more frequently in former years
when there was no regulation of rivers. These floods
would certainly often drive animals into a new environ-
ment. If, for instance, a river floods half a wooded
region, and only spares the extreme corner of it which
borders on a wide steppe, the animals in the part of the
wood that has not been flooded will remain forest
animals, but those that live in the narrow strip of wood
will gradually become steppe animals, because their
continued expansion will drive them on to the open
grass. It is not necessary for the animals to be driven
into other regions by the flood in order to be modified ;
it is enough if they find a new enemy in their new home.
In the struggle with this enemy, the branch species will
be made to differ from the parental species, which will
not be affected by the same agency.

If we bear in mind the continuous geological changes
that have taken place in the earth’s surface since the
enormously remote period of the origin of life, we can
understand that the isolations must have been frequent
enough to account for the infinite variety of organic
species. Lands have sunk beneath the sea, others have
emerged from the waves ; at one place mountain ranges
have been elevated, at another great valleys scooped
out. Land joined on to land and water to water, then

328 DARWINISM AND THE PROBLEMS OF LIFE

separated afresh, and reunited later on. Storms swept
over the earth. Violent hurricanes rooted up whole
forests. Desert-storms buried whole stretches of green
land under sand. Tropical heat alternated with arctic
cold : floods with drought.

When animals that had long been separated came
together again, they were generally so different in
structure and appearance that they could no longer
cross in such a way as to mingle the characters of one
species with those of the other. Even minute changes
in the spermatozoa of the male prevent it from pene-
trating any longer into the ovum and fertilising it.
Moreover, animals are most apt to unite with those of
their own species ; they have a sort of racial feeling that
generally prevents them from crossing with animals of
a different form. An unfamiliar appearance or scent
restrains animals from mixing, and this is especially
true of animals that come together after a long separa-
tion. We know that mammals and birds that have
been kept in captivity for only a brief period have not
only no love to expect from their kind when they are
released, but are actually persecuted. Even the finest
changes in animals often act powerfully on the
sense-organs of their free-living fellows.

It is not only geological alterations of the earth’s
surface that lead to the division of animal species by
isolation, but organisms may be transported into regions
from which they cannot return to their old home and
their fellows. In modern times animals have often
enough been transplanted by men into distant localities.
The Porto- Santo rabbit is a proof of the fact that a

EXTENSION OF EVOLUTIONARY THEORIES 329

Species can be so altered by isolation as to be incapable
of crossing with the parental species. In fact, long
before man crossed the waves on his vessels, organisms
were conveyed into remote districts. Sometimes small
water-snails clung to the legs and feathers of swimming
birds, and were taken far across the sea to strange
islands, where they entered the water once more and
found their proper conditions. In the same way other
aquatic animals travelled far and wide — the minute
eggs, especially, that were easily caught in the feathery
coats of the swimming birds and taken away uncon-
sciously. Land animals also could be dispersed by
birds in this way.

It was by no means necessary to have living vehicles
to convey animals into distant and isolated districts. It
might often happen that a branch of a tree with small
animals sitting on it would fall into the river, be carried
out to sea, and be borne by the currents to distant
localities. In this way, as a matter of fact, branches
have come from America to the coast of Europe. The
eggs, especially, which are comparatively insensitive to
external influences, and the seeds of plants, might be
conveyed in this way. It is certain that many newly-
formed islands have been thus populated.

Not only may the sea transport germs in this way,
but many a flying animal has been taken a considerable
way by stormy winds. Insects and birds often get into
currents of air that carry them to distant localities, and
they often find such a favourable environment there that
they do not think of returning even when it is possible
to do so.

330 DARWINISM AND THE PROBLEMS OF LIFE

The transport of animals into distant lands is often
very useful for their extension. Especially when the
wanderers reach an island that offers them a virgin
habitat — one that has few or no animal species in it —
they may spread in all directions. And as there are all
kinds of spots in the new district, their descendants
in turn may separate into new species, each locality
modifying its inhabitants in a different respect. This
will happen particularly to slow-moving animals, such
as the snails, every valley and every wood giving a
specific modification to its inhabitants. There is no
reason to fear the levelling of the new characters by
crossing with their kind of other districts in the case
of such slow animals, as they have long coupled with
others like themselves before they reach a different
territory.

There are many other means of isolation besides
these. The isolation may only hold during the period
of reproduction ; birds, for instance, that otherwise
mingle together in quest of food may rear their young
in remote districts. In such cases a differently coloured
ground may change the colour of the animals. It was
an isolation of this kind that gave rise to the migratory
birds. The isolation need not always involve an
absolute separation of the daughter species from the
parental species. It is enough if one part of a species
leaves its proper territory, and takes up residence in a
contiguous one of different characters, that meets its
needs. Although there is still a good deal of crossing
at the frontier, there will as a rule be a steady and pure
development of the new species away from it.

EXTENSION OF EVOLUTIONARY THEORIES 33 1

Up to the present we have only seen a preparatory
principle in isolation, which makes possible the formation
of new species. This formation may be brought about
by natural selection after the isolation.

There are also cases in which isolation alone may lead
to the formation of a new species. If a fertilised female is
forced into an isolated district and lays her eggs there,
the young developed from them will not, as a rule, differ
from the parental species. But if the female happens
to have some peculiar characteristic, it will transmit
it to the offspring ; in time the feature will become a
characteristic of the isolated animals, as it can no longer
be absorbed by crossing. In this way isolation may
lead to the formation of a new species without the aid
of natural selection. The isolated variety would be still
more strongly modified if the characteristic in question
were to be accentuated in the offspring ; in other words,
if there were some force in the organisms that caused
variations to advance in a definite direction in the
offspring. We have already found several times that
the transformation of species would be brought about
much more speedily by a principle of this kind than
without it, and we will now inquire whether or no we
may infer the existence of such a force.

•••••••

We have spoken of selective value in the seventh
chapter and seen that it is difficult to conceive how
every little variation can be helpful to its possessor in
the struggle for life. If that is not the case, how can
the variation be preserved and increased? How could
the elephant s trunk be developed from the original nose,

33 2 DARWINISM AND THE PROBLEMS OF LIFE

since even the most favourable variation of the latter
could not perform a single function of the trunk ?

The whole difficulty would be avoided if we could
suppose that variations that have once arisen have
in themselves a tendency to advance in the same direction
in each generation ; in that case, if the elephant’s nose
happened to be rather longer than those of its fellows, it
would be still longer in this elephant’s offspring, and if
the family became isolated, each succeeding generation
would have longer noses. In the end a point would be
reached when the nose would be long enough to be of
service. Then selection would set in, and still further
develop it.

If there were definitely directed variations, it would
be easier to solve a number of other problems. The
importance of amphimixis would be greatly enhanced.
By means of it different directions of variation would be
brought together in one individual, and co-adaptations
would be effected much more quickly. At the same
time, amphimixis would convey both upward and
downward variations to a number of individuals, and
thus generalise useful characteristics, and prevent
injurious ones from spreading, with fatal consequences
to their possessors.

There are many advantages in the theory of definitely
directed variations. Many scientists, in fact, believe
we need the hypothesis, as the theory of selection is,
they say, unable without it to explain the origin of
species. We will now see if there is sound reason for
crediting nature with definitely directed variations.

The expert who has made most use of the principle of

J

EXTENSION OF EVOLUTIONARY THEORIES

333

selection, Weismann, has attempted to apply it to the
germ-cells . 1 He thinks that here also there is a selection
at work — “germinal selection.” The result of this is to
preserve definite directions of variation in the germs.

We have already seen several times that there are
in the germ -cells, which an animal has in its sexual
glands, tiny particles that represent the rudiments of
the future organs, in the sense that, if an animal is
developed from the germ-cell, they determine the several
parts of the body and stimulate their construction.
Hence every part of an animal’s frame is present
rudimentarily in the germ-cell.

These basic particles, which Weismann calls deter-
minants , because they afterwards determine an organ

1 Weismann was influenced by the “ theory of histological selection ”
of Wilhelm Roux. Roux attributed the purposive structure in the
histological, microscopic texture of animals to “ a struggle among their
elements.” We know that sustained exercise or stimulation in the life
of the individual strengthens. The cells are enabled to grow better
under stimuli. Hence when we find a graceful framework in the bones
of the leg, the arches of which always run in the direction of the
greatest pressure and strain, as in the construction of an edifice, it must
have been brought about by the fact that the cells which lay in the
direction of the pressure and strain were most stimulated, and so
formed the strongest bony matter. On the other hand, the intermediate
cells were less stimulated, would grow and act less, and the nourish-
ment they needed would be absorbed by the better situated cells, so
that they would eventually perish. It is thus that the curves in the
osseous structure run only in the direction of the greatest strain. The
cells that lie there have an advantage in the struggle of parts, as they
grow under the constant stimulation, and build up bony substance
at the expense of the adjacent cells, which gradually die off.

Histological selection gives us a luminous explanation of microscopic
structure. But in our opinion it only acts during individual develop-
ment. What it accomplishes is not inherited, but has to be created
afresh in each organism.

334 DARWINISM AND THE PROBLEMS OF LIFE

of the body, consist of living matter, and so must receive
nourishment. Their food must be matter that is
found in the germ-cell, or passes into it from the body.
This matter must, of course, be fluid and must flow
round the determinants.

Nowhere in nature do we find absolute equality, and
so the fluid nutriment will not equally reach all parts of
the germ-cell. Hence a determinant will receive some-
times a fuller and at other times a thinner supply of food.
If it finds plenty of food, it will grow strong and sound,
as all living matter does when it is well nourished.
Another determinant will chance to have a worse
supply of food, and become weaker.

When the determinant is thus enfeebled by happening
to receive a poor supply of nourishment, it will, if an
animal is developed from the germ, have less power to
build up the organ it represents, and the organ also will
be feeble. And when a determinant is strengthened in
the germ by a plentiful supply of food, it will afterwards
build up its particular organ in greater strength. Thus
we see that the variations we find in children of the
same mother at birth are due to chance differences in
the supply of food to the ova. While the ova lay unde-
veloped within the mother’s body, the determinants were
differently fed by the varying stream of nourishment,
and when they afterwards come into action they show
differences in the building up of their respective organs.
Hence the accidental irregularities in the supply of food
in the germ are the roots of variations.

All living matter is able to accomplish work in pro-
portion as it is strengthened by food. We can thus

EXTENSION OF EVOLUTIONARY THEORIES 335

conceive that a determinant, which has increased in
size within the mother through the good supply of food,
will, by reason of its size, attract more food to itself in the
daughter. When the mother’s germ-cell divides to form
the daughter-cells, we know that in the earlier segmenta-
tions of the ovum all the determinants are split into
halves, because first of all must be formed the germ-cells
of the daughters, and these must contain all the basic
particles. When the determinants come into action in
the later segmentations, and gradually build up the
body of the daughters, some of the first cells divided,
the germ-cells retain all their determinants in a quiescent
state. Hence if a determinant became larger in the
mother owing to a good supply of food, it maintained
this size in the germ-cells of the daughters as well, as
after cleavage it always grew again to its normal size.
And, being larger, it needed more nourishment than the
neighbouring determinants that remained small. Owing
to its volume it, as it were, drew to itself the stream of
food circulating in the germ. On account of this supply
of food it became still larger, and retained its size in the
ovum of the grand-daughter, where it again attracted
food, and became larger still. The size increased in
each generation, the determinant grew larger and larger,
and hence the part of the body that it built up showed
a corresponding steady increase or, in other words, a
definitely directed variation.

Does this enlargement of a determinant and the
corresponding organ proceed indefinitely? If this were
the case, there could be no such thing as a specific
type. As the nutrition is exposed to irregularities

33^ DARWINISM AND THE PROBLEMS OF LIFE

at each part of the germ, one part of the innumer-
able determinants would become steadily larger and
the other part constantly smaller. In the same way
the organs of the developed animal would change in
all directions simultaneously. It would be impossible,
in view of this eternal ebb and flow of the determinants,
for an animal species to remain the same for a
considerable period, as we actually find.

Hence Weismann is compelled to attribute to the
germ-substance a faculty of self-correction; that is to
say, generally speaking, a determinant will, if it receives
a somewhat richer supply of food, check it by its own
force, so that it will be neglected, and the determinant
in question will become weaker again. By this self-
regulation the determinants save themselves from
changing incessantly with every variation in the food-
supply. The force of self-correction is only overcome
in rare and exceptional cases of the access of a heavy
stream of nourishment. Then they grow constantly
larger, and with them the organs they bring into
existence.

If the enlargement of the particular organ is useful
for the organism, its possessor is preserved by natural
selection, and therefore also the growing determinant. As
the individuals that vary in this way are selected they
come in time to dominate the species. But if the
enlargement of the organ is injurious, the animal in
question is destroyed and the upward movement of the
determinant is cut off.

Up to the present we have only considered the
quantitative changes of the determinants and their organs.

EXTENSION OF EVOLUTIONARY THEORIES T>37

Irregularities in the food-supply may also lead the
determinants to vary in quality , and so give rise to
qualitative variations in the parts of the body
subsequently. This is believed to be brought about
by a difference in the growth within a determinant of
the many biogens that compose it ; this leads to an
alteration of the structure of the determinants.

Germinal selection thus seems to explain the dis-
appearance of useless organs. These also have, of
course, one or rather several 1 determinants in the
germ-plasm. And while decreasing determinants of the
necessary organs are rooted out with the animals they
are in, as they are insufficiently equipped for the
struggle for life with their undersized necessary organs,
on the other hand the decreasing tendency is preserved
in useless organs, because their possessors are not
extinguished by selection. In this case enlargements
of useless determinants are cut off. Such growing
determinants take the nourishment away from the others,
and cause them to be smaller. But they must not
become smaller, since they build up important and
indispensable organs. Hence rising tendencies in the
determinants of useless organs are cut off, and only
those are preserved that keep them down and reduce
them in size. In this way the determinants and their
organ must gradually disappear within the species.

Here we have the principle of selection. There is
a kind of struggle for nourishment among the deter-
minants in the germ. If one of them has become large

lr lhe eye, for instance, must have several determinants, otherwise
each part could not vary of itself. Hence there must be an immense
number of determinants in the germ.

33^ DARWINISM AND THE PROBLEMS OF LIFE

owing to some chance increase in its food-supply, it is
particularly favoured in the struggle. If it becomes
smaller, it is gradually crushed out, because the food
is taken from it by its neighbours.

Hence on this theory there can only be a limited
amount of nourishment in the germ. If it were
inexhaustible, a tendency to increase in the determinant
of a useless organ would not be prejudicial to its neigh-
bours, as they also would have sufficient food. In this
way organs would not be reduced to a rudimentary
condition, since the rising and falling variations of the
determinants would neutralise each other in the general
crossing, as we have already seen.

According to the theory of germinal selection, there-
fore, the amount of nourishment in the germ is limited.
But each determinant must have enough to maintain
itself. When, therefore, the determinant of a useless
organ becomes weaker and weaker in each succeeding
generation, what becomes of the food that formerly went
to it? As we saw that a determinant only becomes
stronger by taking food away from its neighbours, so
when they become weaker, it must mean that their
neighbours have taken food from them. Thus the
determinants that are contiguous to the determinant of
a useless organ will absorb the nutrition that formerly
went to it. They will grow ; and as they become
stronger they will, according to the theory, continue
to grow, and so will their respective organs. Hence,
on this theory, the parts adjacent to a rudimentary
organ in the body must steadily increase in size. For
the same reason the parts surrounding a growing organ

EXTENSION OF EVOLUTIONARY THEORIES 339

must decrease in size, though not to such an extent as
to cause injury to the organism. But there is no trace
to be found in reality of either process. Therefore, the
hypothesis of a germinal selection cannot be sound.

A number of experts have raised objections to this
hypothesis of germinal selection . 1 It has been pointed
out that we must assume that a determinant which
has increased in size owing to an accidental addition
to its food-supply will sink to its old level as soon as
this addition ceases. It is quite arbitrary to ascribe to
a living force — such as the determinant is — the power to
retain the increased size it has obtained from a better
food-supply when this supply has diminished. If a
gymnast strengthens his arm by exercise, it will not
remain at its full strength if he afterwards abandons
daily practice. If such complex structures as the
muscles of the arm are not able to maintain the force
they have acquired in this way when the exercise is
abandoned, how much less will this be possible for a
minute particle of living matter, which is so much
exposed to vacillations in its supply of food ?

It is just as arbitrary to identify size and force. A
determinant that has increased in size owing to better
nourishment has not necessarily acquired a greater
power of obtaining food than the neighbouring deter-
minants that have remained small. We should be
equally justified in assuming that the shrinking deter-
minants are so much the “ hungrier.” There is no
direct physiological relation between force and size.

1 Professor Emery of Bologna and Professor Thomson of Aberdeen
are the only two distinguished authorities who have fully subscribed to
the theory.

34 ° DARWINISM AND THE PROBLEMS OF LIFE

We might put a long list of questions to germinal
selection. Whence comes the greater amount of
nourishment that overcomes the self-regulation of the
determinants, and thus represents the real source of the
variations ? To what extent can a determinant grow
without injuring its neighbours ? How is it that
irregularities of the food-supply within a determinant
do not often lead to a complete transformation of it,
instead of merely altering its quality a little?

But we have seen that we must reject the theory of
germinal selection, and may quit the subject. In the
next chapter we will return to it for a moment, in
order to disprove it once more from a different point
of view.

Let us now look about us for other principles to
explain how organs reach a certain height owing to
constant definitely directed variations, so that at some
stage they acquire selective value and may be further
advanced by selection.

There are experts who say that external influences
may not only affect an organism in the course of the
individual life, but that these modifications are trans-
mitted in a weaker form to its offspring, and are
accentuated in these, since they remain exposed to the
same influences. Thus in the course of generations the
external agency, which always remains the same, will
modify the animal more and more in a definite direction.
This steady variation in one direction owing to external
influences is called orthogenesis.

Orthogenesis is, clearly, a subdivision of the

EXTENSION OF EVOLUTIONARY THEORIES 34 1

Lamarckian principle, and as we have rejected the one,
we need not linger in discussing the other. However,
we will say a few words about orthogenesis, as in
speaking of the Lamarckian principle we dealt almost
exclusively with the inheritance of changes brought
about by the actions of the animals, their energy and
efforts.

Animals are said to be permanently affected chiefly
by the following external agencies : climate, the char-
acter of the soil, and food. Thus the stimulus of cold
may provoke a thicker coat of hair in many animals.
This will be transmitted to the young, and as the cold
continues to affect them in turn the hair will grow longer
and longer. In this way the animals will vary in one
definite direction as long as the stimulus lasts.

It has been alleged in support of this view that many
poisons make organisms more sensitive the longer they
act on them. That, however, only shows an increase
of the action of a stimulus during the individual life, not
that the increase is inherited.

But there is an experiment that seems to prove the
inheritance of a stimulated effect. In this the pupae of
a butterfly, the large tortoise-shell, were exposed to a
cold of 1 5 0 Fahr. The butterflies that were developed
from them were much darker than the normal specimens.
A couple of these modified animals were crossed, and
from the ova, which were developed under entirely
natural conditions, came caterpillars that afterwards
changed into tortoise-shells of a shade similar to that
of the parents, or slightly lighter.

Had the modification ot the parents by cold been

342

DARWINISM AND THE PROBLEMS OF LIFE

transmitted to the offspring ? It is not necessary to
suppose this. We can just as well imagine that the
lower temperature affected the whole pupa, and even
penetrated to the germ-cells contained in it. As the
wings especially were affected by the cold, that may
have been the case with their determinants in the
germ-cells ; these being so profoundly influenced that
even after the cessation of the cold they brought about
modified wings. “ Medium influences,” such as climate,
for instance, can often not only modify an animal, but
also penetrate it and modify its determinants.

Thus the experiment does not prove that the
modifications of an organ brought about by a
stimulus will on their side influence the corresponding
determinants in the germ ; the stimulus may reach
them directly. We do not know how far or how
often these medium influences on the germ may act,
and so we will not linger over this principle, once it
has helped us to take away an apparent support of
the Lamarckian theory.

The explanations offered us by the hypothesis of
an orthogenetic action of constant stimuli are not
satisfactory. The Lamarckians say, for instance, that
certain mammals, such as whales and walruses, have
almost entirely lost their hairy coat owing to the
constant action of the water. In other animals the
water is said to have formed horny plates on the
mucous lining of the palate, as in the tortoises, the
duck-bills, and the whales. We may ask, then, why
the water has not reduced the fur of the otter, the
beaver, the seal, and the water-rat, and why we find

EXTENSION OF EVOLUTIONARY THEORIES 343

no horny plates on the palate of the crocodile, the
dolphin, and other aquatic animals ? The external
influence is the same in the case of all these animals.
Why is there a different reaction in the various animals ?

And there is yet another question. What is the
extent of the influence of external stimuli ? If the
water causes horny plates on the palate of certain
animals, they must continue to grow indefinitely. If
apes have acquired certain protuberances by sitting,
these will go on growing until they become monstrous
swellings, if the effect of the stimulus is increased
with each generation.

It has been said in reply that an organism at length
inures itself to these permanent stimuli, and ceases to
react on them. But this only raises another difficulty.
What is the basis of this power of adaptation ? Perhaps
it will be said that it depends on a certain adaptive
power of the body. But how did this come about ?
And when the animal has become inured in this way
what is the service of it ? Moreover, it must last for a
longer or shorter period in different animals.

In a word, we see that the action of external stimuli
in the transformation of organisms must be very slight.
The real force must lie within the animals themselves.
It is due to this that the body responds to external
stimuli in so far as it is to the interest of the animal.
The adaptiveness of living things, which must have a
scientific explanation, puts out of court all the Lamarckian
hypotheses, and therefore also orthogenesis.

* • • • • • •

It is the opinion of many authorities that natural

344

DARWINISM AND THE PROBLEMS OF LIFE

selection alone does not suffice to explain the origin of
species, and that we are compelled to postulate a pur-
posive internal formative energy in organisms. But
before we deal with these writers, we will describe a
recent theory which does not directly reject natural
selection, but greatly restricts its sphere of influence.
This is the “mutation theory” of the botanist, Hugo
de Vries.

De Vries questions especially whether the actual forms
of life are due to ordinary variations. He says that
they are not inherited pure , and appeals to artificial
selection, as, for instance, in many kinds of grain. These
are never independent of selection, because as soon as
cultivators cease to watch and select them, they quickly
return to the parental species. Thus no character can
be fixed by natural selection to such an extent that it
will remain as a permanent quality of the new species
when selection has ceased.

There is a second reason why natural selection cannot
have created the actual forms of life from variations.
The variations, he says, are restricted ; they cannot
increase indefinitely, and can at the most only double
the original character. We have, for instance, con-
siderably increased the amount of sugar in the beet
by selection, but that is all. Further, there has been
no increase in the size of gooseberries since 1852,
though one cannot see any reason why they should
not have become as large as pumpkins. There must
be an internal limit to variability.

Hence de Vries believes that ordinary variations
cannot have produced the actual species. They must

EXTENSION OF EVOLUTIONARY THEORIES 345

be due to special variations, which he calls mutations.
These mutations have long been recognised ; they
rarely occur, and the feature of them is that the
organism is modified by them at a bound, in several
directions at once. Thus, amongst a number of plants
that de Vries was cultivating, most of which varied in
the usual manner, there were some that departed from
the species in several directions simultaneously, and so
were very conspicuously altered. When de Vries
crossed these “ mutations ” with each other they
produced plants of just the same kind. In other words,
contrary to the variations, the mutations retained their
new characters from the beginning when purely cultivated.

Species have been brought about, he thinks, by these
mutations. Owing to certain internal causes the species
have, he thinks, suddenly divided into several with a
number of new characters which they all retained.
These mutations take no particular direction ; they are
partly useful, partly indifferent, partly injurious to the
organism. Natural selection weeds out the unfit, but
has no influence on the survivors. It cannot improve
the latter ; it must take the individuals as they are,
modified simultaneously in several directions.

Thus, whereas we have so far considered the trans-
formation of species to be due to the fact that each
organ was slowly modified in connection with its
environment, in the sense of adaptation, this new theory
suddenly shatters the whole conception. When we
reflect on this we are disposed to join those who reject
the mutations as the formers of species. We know
that the species are made up of adaptations, and these

34^ DARWINISM AND THE PROBLEMS OF LIFE

can only gradually have been evolved from variations.
The complete adaptations cannot possibly have arisen
from a modification of the organism by mutation ; that
would be an excessive trust in the fortune of chance.
On this theory a mutation of a butterfly’s wing would
imply that all its parts suddenly developed different
colours. But we must not expect that in this hap-
hazard variation the colours would harmonise in such
a way as to form a picture of a leaf ! Even if an
imperfect leaf-design were formed, it would not be
improved at the next mutation, as the colours of all the
parts would change at once ; even if the colours that were
wanting before now made their appearance, the parts
that had been rightly coloured would be destroyed.
Let us recall our illustration of the twenty dice.
Suppose the adaptation consisted in all the dice showing
the six. The shaking of them in the cup and throwing
them would represent a mutation. However many
times we try the experiment we shall scarcely succeed
in making all the dice show the six. It can only be
done by throwing each die separately until it gives a
six, and then letting it stand. But that is just the way
in which variations occur, and the fixing of them is left
to natural selection.

Another objection to the theory of de Vries is that
the mutations must be neutralised by amphimixis with
normal animals, as they occur in so few individuals. It
will very rarely happen for them to be of so favourable
a character and at the same time for such a crisis to
come upon the species that all the individuals without
the mutation will perish.

EXTENSION OF EVOLUTIONARY THEORIES 347

Hence the multiplicity of our actual species cannot
be due to mutations. What can we say to de Vries’s
objections to variations ?

It has been rightly pointed out that these objections
are unsound. In the first place, we have really pro-
duced new races of dogs and pigeons by artificial
selection, and these have retained their new characters
when crossed with their own kind. We may therefore
assume that in natural selection also the modified
animals will retain their characteristics when the
selection has ceased. But even that is not necessary.
Selection does not cease to act even in pronounced
species ; it watches unceasingly over the animals, and
continues to act on them. Hence the variations, even
if they had a tendency constantly to slip back, must
lead to new species, as natural selection always cuts
off all instances of reversion.

Secondly, even if after a time we reach a limit that
we cannot pass in artificial selection, it does not follow
that this is the case in nature as well. We can only
continue to select as long as the harmony of the various
parts is preserved, and we do not know what other parts
of the body we must attend to in our selection if the
object we are breeding is to have unusual features. If
we want to increase the gooseberry to the size of a
pumpkin, it is certainly not enough to select the trees
that have the largest berries. If we want very large
berries we must also have changes in the plant’s fibres
for conveying water and sap, the branches must be
thicker in a word, there must be a number of changes
that are not entirely within our knowledge or control.

34-8 DARWINISM AND THE PROBLEMS OF LIFE

But if we reflect on monstrosities in nature, the parasites,
and the deep-sea animals (some of which have mouths
of extraordinary proportions, others have stomachs that
can take in a larger fish than the devourer, and others
have eyes on the end of long stalks), we must ascribe
to variations a faculty of indefinite advance. Natural
selection may produce the greatest monstrosities if they
are capable of life and are adapted to their environment.
Japanese breeders have even succeeded in creating cocks
with tail-feathers four yards long by artificial selection.

We turn now to those writers who ascribe the
development of the organic world to a formative energy
that was present in living matter from the beginning.
This energy is supposed entirely of itself to impel
organisms to assume more and more advanced forms.
Living things would have the forms they exhibit to-day,
on the whole, even if they had been subject to quite
different influences, and if the geological changes of the
earth had been different. Natural selection, they say,
does not create species by adapting animals to new
conditions, but the animal forms were built up by the
internal force, without any influence from external
conditions. This was done by the species diverging
from each other in characteristics of no value in animal
life.

We need not delay long with this theory, because we
know that the foundation of it is unsound. We have
seen that the species is first and foremost a collection
of adaptations. But adaptations cannot arise from some
independent formative energy working on its own

EXTENSION OF EVOLUTIONARY THEORIES 349

account. It is of their very essence that they be in
harmony with the external conditions of life, and these
are brought about by a totally different force — the force
that effects the geological changes of the earth. As it
is a fact that the organisms have always been modified
in correspondence with the geological changes of the
earth’s surface, since the adaptations always harmonise
with the new condition of the earth, the two forces
must go together like two mutually regulated clocks.
And as the forces have nothing to do with each other,
we can only explain their agreement by postulating a
third force that controlled them from the start. If we
do this we abandon all attempt at scientific explanation.

If we want to explain a phenomenon satisfactorily we
have to bring it into line with a more general and better
known phenomenon within our experience. But we
must not ascribe to this phenomenon any characteristics
which we do not really know to be present in it ; and
in experience we are only acquainted with the corporeal
and with movement, matter and force, the material of
chemistry and physics.

What do we mean by reducing one phenomenon to
another ? It means that we can show the one to be a
necessary consequence of the other. The phenomenon
to be explained must have a cause, of which it is the
necessary effect. We have, therefore, satisfactorily
explained a phenomenon when we show that it is the
effect of another of which we know by experience that
under certain known conditions it is bound to produce
the effect in question, and that these circumstances are
actually given. Thus we explain the luminosity of

350 DARWINISM AND THE PROBLEMS OF LIFE

lightning by showing that electricity is generated by the
friction of certain bodies, that from this a luminous
spark must arise, and that these conditions are realised
in a storm.

In the same way we give the most satisfactory
explanation of the phenomena of life when we trace
them to the known processes of physics and chemistry.
However, our actual biological knowledge is much too
scanty for us to give this explanation in full. But we
may ask if it is possible in a general way to give a
physico - chemical explanation of the processes of life,
or if it is not in the very nature of life to elude such an
explanation. Here we find two contradictory opinions.
One holds that a physico - chemical explanation of life
is possible ; that is mechanism. The other denies that
it is possible ; this system is known as vitalism.

All that we have said hitherto was based on the
mechanical conception. The principle of natural
selection, which we have chiefly employed, enabled us
to give a mechanical interpretation of the organic world.
If living things came into existence and were trans-
formed by natural selection, we need only physico-
chemical forces to explain the process.

The Vitalists say, however, that natural selection is
just as incapable as any other mechanical principle to
explain life. Let us see which property of organisms
it is that the Vitalists declare to be particularly
inexplicable by physico-chemical means.

In the first place, they object that the Mechanicists
have never yet succeeded in giving a purely physico-
chemical explanation of the vital phenomena. But this

EXTENSION OF EVOLUTIONARY THEORIES 35 1

merely implies that our present means and knowledge
do not suffice for constructing a mechanical explanation ;
it does not follow that there will always be insuperable
difficulties in the way of it. On the contrary, we have
already good reason to say that a mechanical explanation
of life is possible. We have already given a physico-
chemical analysis of some aspects of the vital processes
which were formerly attributed to a vital force. There
are certain substances that are only found in the living
body, yet have been artificially produced by chemistry.
Uric acid is the best known of these.

The Vitalists reply that we must put outside the
category of real vital phenomena all aspects of the vital
processes that can be conceived as purely mechanical.
But it has been rightly pointed out to them that the
problem before us is : Can the vital processes be
conceived as physico-chemical? If the Vitalists say it
is the characteristic of vital phenomena to be incapable
of being conceived as physico-chemical, they are begging
the whole question.

I have already said that we do not know under what
conditions the chief elements of the organic body, the
albuminoids, are produced. Living albumen is still an
unsolved problem for us. Hence our knowledge of the
living substance is as yet much too scanty for us to
construct successfully a mechanical explanation of the
vital processes.

It has been established by careful research that the
same amount of force is used up by an adult organism
in its vital activity as is taken into it with its food.
Hence all the actions of the body are exactly

352

DARWINISM AND THE PROBLEMS OF LIFE

proportioned to the amount of force contained in the
food taken. But if these actions proceeded from a
special vital force, the amount of energy introduced in
the food would be superfluous in the body.

Thus Vitalism is inconsistent with the law of
the conservation of energy. It has, therefore, been
modified into what is known as Neo-Vitalism. Generally
speaking, this theory admits that the same physico-
chemical forces are at work in living things as in
inorganic nature. But while the mechanical processes
alone are found in the inorganic world, living things
are also subject to other principles which are not found
in inorganic nature.

We shall see something of this “teleological”
governing force in the next chapter. Here we will
only say that a unified conception of the organic and
inorganic worlds is preferable to the Vitalistic, especially
as we know only mechanical events as facts. The
Vitalists do not help us to understand the organic
world. They only question whether the problem can
be solved mechanically.

There are, they say, two characteristics of organisms
in particular that cannot be understood mechanically —
their form and their purposiveness.

It is true that all living things have a form, not only
the individuals as a whole, but even in their smallest
parts. The forms of organisms are conditions of
equilibrium. If we recall the simplest forms of living
things, those of the tiny protozoa, we find that they
are generally globular. The round shape is the foi m
of equilibrium of a fluid body, and we saw at an earlier

EXTENSION OF EVOLUTIONARY THEORIES 353

stage that protoplasm is fluid. Thus the form of the
lowest organisms may be compared to that of a drop
of water. The shapes of other protozoa are explained
by the membranes that cover them, which cause the
departures from the globular form by their inequality
in thickness and extensibility. The forms of the lowest
organisms are, therefore, parallel to forms in the
inorganic world. In fact, in the latter there are forms
that are far more difficult to understand than those of
the protozoa — the crystals.

But how do we explain the forms of the higher
organisms ?

We have seen that these forms have been developed
from the lower ones. No extraordinary forces were
employed in this evolution ; the new organisms
were in each case the outcome of an accidental, local
coincidence of physico-chemical conditions.

But is not chance itself incapable of being understood
mechanically ?

No. Chance, in our sense of the word, has nothing
to do with the miraculous. Every accident, on which
we count, is the ultimate effect of a whole chain of
successive causes and effects, in all of which only
natural forces are at work. We are, therefore, quite
convinced that “ chance ” is to be explained physico-
chemically ; though we grant that the causes which
have determined it are not known to us. We have an
excellent illustration of the matter in a ball that has
been thrown on the ground. Chance determines at
what spot it will stop rolling ; in other words, the spot
cannot be calculated in advance, because the various

354 DARWINISM AND THE PROBLEMS OF LIFE

forces and conditions that impel the ball towards it are
not known to us.

The Vitalists say that none of the marvellous forms
of the organic world can have been brought about by
chance, any more than the chance agencies that effected
the geological changes of the earth’s surface could have
constructed a Parthenon or a steam-engine. But it has
been pointed out that even these structures owe their
origin to chance. Did James Watt go to work with the
idea of making a steam-engine ? Not at all. He came
by his first thought by chancing to observe the pressure
of the steam in lifting up the lid of a kettle. He then
confirmed his observations by assiduous experiments,
and so he and his successors erected machines that
advanced step by step, always selecting the useful and
rejecting the useless. The Greek style of architecture
arose in the same way. Natural selection acts
analogously. We will, therefore, regard its explanation
of the forms of the higher organisms as satisfactory.

Does the purposive reaction of organisms to external
stimuli point to the presence of an internal vital
force ?

It is suggesed that such a force, independent and
self-existent, must react purposively on all influences,
just as a magnet attracts all pieces of iron. But we
know that this purposive force often fails in living
things. An amoeba will take into its body and retain
for some time a particle of stone lying in its path, just
as it does with food. The relation of flowers and
insects also is often unsuitable. Many animals have
died out because they could not adapt themselves

EXTENSION OF EVOLUTIONARY THEORIES 355

suitably to their suddenly altered conditions oflife. We
saw that, generally speaking, animals have the power of
suitable reaction or adaptation only in their customary
environment. A mole-cricket tries to bury itself in a
glass plate instead of running away ; a bee stings a
human being, though the sting will be fatal to itself,
and so on. If the purposive reaction in the vital force
of animals were independent of the external world they
would be armed against all contingencies ; and that is
not the case. Far more probable is our hypothesis that
the animal’s power of adaptation has arisen by gradual
development under the controlling influence of external
agencies.

Matter and force determine the series of cause and
effect, as we know from experience. To this no
exception has been found. On the other hand
there are many exceptions to the purposive power of
organisms ; and that shows it is not determined by any
internal law.

We have a proof of non-purposive development in the
rudimentary organisms. Humanity would be far better
off if the human frame contained no ccecum. How
frequently, moreover, the “purposive power” goes
astray during embryonic development, and brings into
the world hydrocephalous children and other deformities.
Then there is the power of regeneration ; it would be
of great service to all animals, but is found well
developed in very few. Do not some animals have a
larger measure of it than others? Why, then, are
they particularly favoured ? In a word, the vital force
raises so many new difficulties that are not raised by

356 DARWINISM AND THE PROBLEMS OF LIFE

the mechanical conception that we are bound to prefer
the latter. Selection is precisely proved in a most
striking way by the imperfectness of the adaptations.

Finally, the objection has been raised against the
mechanical theory that all evolution pre-supposes some-
thing that cannot be explained physico - chemically.
This is the will to live. The struggle for life is not
imposed from without on organisms ; it is rooted in
their own will. Selection would accomplish nothing —
it would effect no improvement if living things did not
strive to maintain themselves and reproduce.

We cannot accept this view. The will to live is
synonymous with the impulse of self-preservation.
This is an instinct, and we said that there is no difficulty
in attributing the origin of instincts to natural selection.
Moreover, the will to live and to reproduce is not
primary. It is certainly not present in the lowest
protozoa. These have no will to nourish themselves.
They travel about and take into their bodies everything
that comes in their way. If the particles are digestible
they are used for building up the animal ; if not, there
was no use in absorbing them. When the lowest
mobile algae swim towards the light, they do not do
this in virtue of a will to live, but because an attractive
force has been developed in their frame by selection that
impels them towards the light, which is important to them.

Still less can we speak of a will to reproduce. The
cleavage of an amoeba clearly means merely that when
it has absorbed a certain quantity of food it breaks up of
itself, just as steam on the window runs down at length
in drops.

EXTENSION OF EVOLUTIONARY THEORIES 357

A considerable number of animal characteristics have
been produced by a purely passive selection. Protective
colours, for instance, are of this kind. In this case the
least conspicuous animals are preserved without any
action on their part.

Now that we have shown the untenability of the
bases of this theory, we need not go into its consequences
in detail. When it is said that the basic particles
were fully developed by their impulse to act, that the
action of the will in the body leaves behind it an
hereditary disposition, and that the animal organisation
is embodied volition, we can only say that these
statements postulate the Lamarckian principle which
we have rejected.

We conclude, therefore, that the value of natural
selection consists in its enabling us to form a unified and
mechanical view of the world. In order to appreciate
this fully, we will now go on to consider the nature and
the significance of mechanism.

CHAPTER XI

THE MECHANICAL SYSTEM AND ITS LIMITS

An attempt to refute the theory of evolution. Establishment of
theories and investigation of details. Causes and effects. Infinity
of same. Impotence of science. Infinite variety in the products
of organs. The infinite diversity of the universe. Purpose.
Mechanical and teleological causes. There is no end in the
development of animals. Sexual selection, orthogenesis, and
germinal selection are teleological. Purification of the theory
of selection from teleological elements. There are no higher
and lower animals. A high grade of organisation gives no more
advantage to an animal than a lower. Natural selection is not an
absolute principle of betterment. The scientific method of
research. Infinite diversity of the universe. Comprehension
of same by concepts. Abstraction of the universal. What a
natural law is. Ultimate constituents of bodies. Comprehension
of the world by ultimate elements. Mathematics. An ether
without properties enables us to grasp the world. Does ether
exist ? Are psychic processes to be conceived corporeally ? The
methods of psychology. Consciousness. The world and the
soul are only to be conceived as contents of consciousness.
Transition from science to theory of knowledge.

As we have in the previous chapter refuted the

objections to the theory of selection, we may now state

our position in the following theses :

The present living inhabitants of our planet have

been gradually developed from the simplest forms in

the course of long terrestrial epochs. The latter

themselves have been developed from inorganic matter.

The evolution was and is the work of natural selection,

a principle that rests on the general laws of nature, and

358

THE MECHANICAL SYSTEM AND ITS LIMITS 359

so enables us to understand organisms on a mechanical
basis.

We have already observed several times that there is
no longer any serious objection urged against our first
thesis, or against the general theory of evolution. It is
true that objections continue to be raised by a few men
of science. A book appeared recently in Germany that
spoke of “the break-up of the theory of evolution.” But
the gist of the work was merely that we cannot establish
with certainty the descent of the various classes of
animals. The objection overlooks the fact that the
theory of selection has done enough as a scientific
theory when it shows in a general way the reasons
why we must suppose one species to have been evolved
from another; of this we have plenty of instances.
The fact that we cannot for the moment determine the
stages of development of the various classes makes no
difference to the general theory ; in fact, even if it were
true that we could not reconstruct, even in broad out-
line, the genealogical tree of an animal group, this
would not in the least affect the truth of the theory of
selection. The detailed efforts to construct the genea-
logical trees of the animals lie outside its province ; they
are not scientific at all in the same sense. They come
within the range of a totally different science — history.
We shall see this better if we consider the historical
side of the theory of evolution.

Objections of this kind, therefore, do not injure the
theory of selection or of evolution ; they merely show
that in many cases it is difficult, if not impossible, to
trace the ancestry of an animal. But no reasonable

360 Darwinism and the problems of life

man of science has denied this. The transformation of
one species into another can only be established with
certainty in a few cases — such as that of the Porto-
Santo rabbit. That is natural enough, as this trans-
formation lasts far too long and is far too gradual to
come under human observation. We may, therefore,
readily grant that we cannot establish the selective value
of variations in particular cases. We cannot do this
solely because we do not know what is of value in the
life of the animal. And if that is impossible with living
animals the conditions of whose life are known to us, how
can we be expected to show the selective value of
variations in animals that have evolved to their present
forms in earlier ages. We do not know the accidents —
the isolations — that determined selection to modify them
in a particular direction, and so cannot know what has
selective value for this particular direction. All that we
can say is that a variation will have selective value if it
favourably influences the strength of the particular
animal, as that will lead to an increased multiplication
which must be gradually prepared. It is clear, at all
events, that there must be a large number of small
variations with selective value, and that it is incorrect
to say that there are hardly any variations with selective
value.

The action of natural selection cannot be directly
observed in nature, we must admit. But this admission
does not cover a defect of the theory of selection.
There are many theories the truth of which cannot
be established by direct observation. It is said that
light is due to the vibration of the minute particles

THE MECHANICAL SYSTEM AND ITS LIMITS 36 1

that fill the universe. But has anyone ever seen this
vibrating ether ? It is the same with the theories that
explain the nature of electricity and magnetism. The
value of scientific theories is not that they can be
verified by direct observation, but that they bring all
the material under one point of view, and so make
it intelligible. Natural selection prevails wherever
there is life.

• ••••••

Can science make the whole world intelligible to
us, then ?

When a man of science seeks to explain a
phenomenon he looks for the cause of it. When he
has discovered this cause his task is not over ; the
question then arises, what was the cause of this cause ?
Even when this is settled the work is not ended.
Every cause is at the same time the effect of another
cause. We never reach an ultimate cause that is
cause only and not effect, because the chain of cause
and effect, the various links of which are the
phenomena of the universe, is infinite.

We have, for instance, discovered the cause of the
erosion of the sea - coast in many places to be the
waves of the sea, the cause of these to be the lifting-
up of the surface of the water, and the cause of this
again to be the attraction of the sun and moon.
Science presses onward, and brings more and more
links of the chain of causes out of the depths of the
perplexing ocean of events. Will the whole chain
ever be brought to light? No, that can never be.

362 DARWINISM AND THE PROBLEMS OF LIFE

It is the very nature of the infinite that we can set
no limit to it, before or after.

We may go further. The distance from the earth
to the sun is very considerable, but it can be
expressed by a definite figure, and so is finite. When
the sun is at its zenith and we stand on a chair, we
are really a little nearer to it, but may say that the
difference is insignificant in view of the colossal
distance. However, the cosmic chain of causes is
really infinite. No matter how many causes we

determine, we do not come a single step nearer to
infinity. Hence the results of scientific research are,
in comparison with the reality, not only very slight,
but almost nothing, and will ever remain so.

When we inquire into the nature of the matter
that composes the whole world we are face to face
with infinity once more. However much we sub-
divide bodies we always come to other bodies, and
never to anything that gives us an insight into their
essence. That is easily understood, as it is the
property of every body to be divisible ; hence the
smallest particles must always be bodies and nothing
else.

Hence bodies are divisible to infinity. And in this
process we encounter a second infinity. No part of
a body is like another, so that when we break up
matter, we discover an infinite diversity of its particles.
It may be said that that is not true; that when we
analyse matter we come to the elements, some
seventy in number, of which all matter is composed.

THE MECHANICAL SYSTEM AND ITS LIMITS 363

Thus the ultimate particles of bodies would not be
infinitely varied. But who can tell us that these
ultimate elements, the atoms, do not differ from each
other? No one has ever seen an atom. We know,
at all events, that when we break up an element such
as gold we do not produce absolutely identical
particles ; they always differ in contour, in size, or
other characters, as we see clearly when we examine
them carefully, if possible with a microscope. It is
true that they have much in common, but they are
not therefore equal. If it is said that their differences
are so slight that we may overlook them, the state-
ment is arbitrary, and not based on the nature of
things. It is not at all evident in nature that the
general is more important than the individual.

When we see a couple of horses at a distance they
often seem to be alike, but we find on going nearer
that they are different. It is certain that the particles of
the elements differ more from each other than our
feeble eyes can detect. Finally, for all we know it may
be that if we pushed our analysis far enough we should
come to elements with nothing in common.

The third infinity is the diversity of phenomena and
bodies that meets our eyes. A science that would
investigate the world cannot master its material ; the
infinitely numerous and varied bodies and processes
cannot be described in detail, much less investigated.

Must we then fold our arms ? Can we never grasp
reality as it is.

No. No human mind can grasp the world as it is.

364 DARWINISM AND THE PROBLEMS OF LIFE

It must first make it intelligible — must transform it.
Then it may succeed in grasping the world.

Mechanism endeavours to understand the world, and
has succeeded to a certain extent. But before we inquire
how it solves the riddle of the universe, we must first
make clear the unity of the world, even in relation to
organisms, which it implies. We have, therefore, to
exclude entirely from the organic world the non-
mechanical theory.

• ••••••

We saw something in the previous chapter of theories
that deny the identity of living with lifeless matter.
We rejected these theories. Now we will deal with
the common ground-work of them all.

They hold that the chief characteristic of living sub-
stance is its aiming at an end. They think that there is
latent in every ovum a force that comes into play in the
development of the ovum, and controls the evolution so
as to attain the end — the fully-formed organism. In the
same way, they say, there was a force in living matter
from the start that aimed at advancement, and has con-
tinually realised its end — the creation of higher forms —
until it produced man as the crown of its work.

We give the name of teleology to the view that the
evolution of living things was controlled by a plan
or end.

There is, of course, causality in the teleological system.
But it differs from that we have already considered. In
ordinary causality the cause thrusts the effect from it, as
it were ; causes and effects follow each other eternally,

THE MECHANICAL SYSTEM AND ITS LIMITS 365

without there being any aim that influences the whole
series. What often seems to us to be the goal or end
of the series is only a link in it, followed uninterruptedly
by other links. Thus, for instance, the construction of
a living thing from the ovum is not a halting-place in
the series of causes ; they continue their endless course
beyond it.

But in teleological causality there is such a thing as an
end or purpose. It is true that here also cause and
effect follow necessarily on each other, but the end has
the power of attracting causes and effects to itself so that
they do not run beyond but realise it. According to the
teleological view the construction of an organism is the
end which the whole embryonic development is aiming to
realise. The end, as it were, observes and controls the
series of causes, and is realised in the ultimate effect.
The very first causes were controlled by a fact that was
still in the future. The ordinary causes, which we have
discussed, can only produce an effect when they them-
selves have already been brought into existence as an
effect. Teleological causes or ends act before they are
themselves realised.

We rejected in the previous chapter the notion that
organisms aim at the realisation of ends. Seeking an
end would be the greatest conceivable form of purposive-
ness. But the rudimentary organs, the erratic instincts,
and the many imperfections in nature prove that the
evolution of animals is not wholly controlled by pur-
posiveness. Moreover, how is it that an end is merely
sought in some animals and realised in others? We

366 DARWINISM AND THE PROBLEMS OF LIFE

may recall, for instance, the vascular system of the
amphibians and birds ; the former have clearly a much
more ingeniously constructed heart than the latter.

In the individual development of an animal, where
there seems to be an end, the processes are regulated
by natural selection, a mechanical principle. The germ
cells give rise to others in unbroken succession and also
the bodies surrounding them, which are continually
dissolved again into inorganic matter. Thus the
causal series of the living matter continually sends out
side-branches, as it were. The main trunk endures
uninterruptedly as life ; the effects of the side-branches
lead into the inorganic world and continue indefinitely
there as lifeless processes.

If the construction of a living thing were the aim of
the germ cells, impelling them to realise it by their
development, how is it that it so often fails ? Why are
there mis-births? Why, above all, is the “end” no
longer fully attained when natural selection has ceased
to act ? Surely the degenerations effected in panmixis
show clearly enough that the ontogenesis is not aiming at
an immutable purpose. If natural selection ceases, the
harmony of development is always, though gradually,
disturbed, and some misshapen object formed. Civilised
man is always inferior in strength, hearing, and sight to
his ancestors and his savage fellows. How is it that the
end has suddenly lost its force in his case?

It is clear, therefore, from panmixis that there is no
end controlling the development of animals with a view
to its own realisation. Such an end would not be

THE MECHANICAL SYSTEM AND ITS LIMITS 367

dependent on natural selection, a principle that it really
excludes. The development of civilised man is becoming
less and less purposive ; the fact that men are not yet
more short-sighted and weaker is because panmixis has
not yet lasted long enough to bring about conspicuous
degenerations, and because natural selection has not
entirelyabandoned man even in regard to his bodily frame,
as in the majority of cases excessive weakness or short-
sightedness prevents a man from earning his living and
so from reproducing. The majority are always con-
tributing new blood to the “higher orders,” and this
improves the corporeal debility that distinguishes the
latter on account of their condition and occupations.

Science, especially, has no need of teleology, because
it cannot regard as facts causes that act before they are
themselves realised. According to the teleological view
the evolution of the actual organisms must aim at a
remote end, and this end must accomplish their trans-
formations. If that were so we should have to give up
all idea of a scientific investigation of the organic world.
We could not study this end, as the future does not
exist, and so we can never determine in what way the
end regulates the modifications of animals; we cannot
detect their real causes.

For these reasons we must reject the teleological
causes that are supposed to influence the beginning
from the end, these “ final causes ” as they are called in
opposition to the “ efficient causes,” which proceed
gradually onward. We can safely do this, because the
principle of selection enables us to give a purely

368 DARWINISM AND THE PROBLEMS OF LIFE

mechanical explanation of the evolution of living
hings.

•••••••

We know that the theory of selection is a mechanical
principle. Just as the pebbles are rolled about in the
stream, the smaller ones going farther and the larger
remaining behind, so we find the action of natural
selection. Chance — or causes and effects that are

unknown to us, but which we know to be of a
mechanical nature — determines whether the whole
species is to be transformed or whether it divides.

The principle of selection itself has been generally
recognised as mechanical. But this has been denied
of its two postulates. It has been said that the varia-
tions are not universal, or do not diverge in all directions,
but only in a few. If the variations were universal why
could we not produce, for instance, a cock’s spur on a
pigeon by selection ?

We need not delay with this difficulty, as we settled it
in dealing with the mutation-theory in the previous
chapter. We cannot breed a spur on the pigeon
because we do not know what varieties of pigeons to
select for the purpose. That the occurrence of varia-
tions is not the same in every species is clear from the
fact that many animals of very different classes have
assumed the same form. I need only mention the
parasitism of the spiders, crabs, and worms . 1

1 If we wish to form a scientific and harmonious conception of the
world, we can only use mechanical principles in explaining it.
Mechanical natural selection can do nothing without postulating
variations. Hence if we wish to explain the organic world mechani-

THE MECHANICAL SYSTEM AND ITS LIMITS 369

Against heredity the objection has been raised that

ordinary variations were not preserved, and that it was

cally, the variations must depend absolutely on mechanical grounds.
If it is assumed that the variations only follow definite directions and
are restricted — if, in other words, there are limits in the organisation of
animals that prevent the variations from passing a certain measure —
they are no longer mechanical ; in that case there is a force in
organisms that avoids unserviceable and aimless changes — a purposive,
teleological force. Variations do not then depend on chance — which
alone would be mechanical — but are directed according to definite
internal principles.

Thus we see that variations cease to be mechanical as soon as they
are assumed to be definitely directed and limited. Natural selection
is then no longer a mechanical principle, and a unified conception of
the world is impossible. As soon as a Mechanist recognises variations
of that kind he abandons the possibility of a harmonious system, and
is no longer a Mechanist. It is just the same if he recognises other
principles that can be shown to be teleological, as we shall show
presently of sexual selection and the Lamarckian principle. If he
would remain a Mechanist he must abandon them in this case. That
is mere logic and consistency. But even if one holds the mechanical
system to be impossible and unattainable, these theories are none the
less useless, if they are teleological. He considers the development of
living things to be due to a purposive internal force, and so must
regard natural selection, the Lamarckian principle, etc., as merely
subsidiary. These theories have real value only for a Mechanist, and
they must, therefore, be mechanical.

It is said that if there are no limits fixed in the nature of the animals,
natural selection would be able to equip the horse with wings and
create all the fantastic forms of our legends and fairy tales. How do
we know that it cannot? Is the legendary dragon more wonderful than
the ichthyosaurus or the plesiosaurus ? Does it not show an unlimited
capacity when a sort of tape-worm is developed from a spider, and a
being that scarcely looks like an animal out of a crab? The point is
worthless on other grounds. The transformations of the animal world
are due to the fact that those survive which are most in harmony with
their conditions at the time. Hence when it is said that certain animals
ought to have arisen, one must have had some knowledge of the
conditions of life of the evolving sped s at the time. But we do not
know them — in the case of the horse, for instance. Horses with wings
would only be developed if the conditions of the horse were such that
the best leapers survived (compare the origin of the insects). But that
can hardly have been the case.

2 A

370 DARWINISM AND THE PROBLEMS OF LIFE

not the adaptations, but the indifferent characters, that
were retained in the species. We have already settled
these difficulties.

Hence natural selection with its two postulates is a
purely mechanical principle that has never been unsettled
by any solid objections. And as we have concluded that
it alone accounts for the evolution of living things, we
can answer “yes” to the question whether the organic
world can be conceived in a purely mechanical sense and
whether it can form part of a unified cosmic system. At
the same time we admit that it is not yet possible to give
a satisfactory explanation of the vital phenomena.

However, it is only pure natural selection that serves
to explain the organic world. All the auxiliary theories
are teleological.

This is true in the first place of sexual selection, or at
least of the second category of sexual selection — choice
on the part of the female. In this instance we should
have an end acting before it is realised. When a
musical apparatus was developed in the cricket, for
instance, we may very well ask how the females came
to be attracted by this particular sound at its first
occurrence, while they take to flight at all other sounds ?
Even if it is said that curiosity drew them to the new
sound, it has not yet been explained how it is that the
females yield more readily to the fiddling crickets than
to their silent fellows. In every case we have to assume
that the chirping sound pleased the females. The same
must be done when it is sought to explain any of the
other masculine characteristics. The females must have

THE MECHANICAL SYSTEM AND ITS LIMITS 37 1

some sense for them before they are developed, if they
are to be recognised at once and selected ; and they
must be equally sensitive to any increase in the
characters. Hence the male characteristics act before
they exist ; in other words, sexual selection even in its
simplest form is teleological . 1

The Lamarckian principle, also orthogenesis, rest on
teleological foundations. The statement that certain
organs have attained their higher development by
inheriting the effects of exercise supposes that the
organism in question acts consciously, and that there
is a special disposition in the animal’s body. And when
explanations are offered us such as that pressure causes
the skin to become thicker in some animals and thinner
in others, that is to credit the organism in question with
a purposive adaptability and regulate this so as to attain
the end that is to be explained. The Lamarckian
principle postulates a force in animals, in each case, that
strives to attain an end, and exercise and other agencies
merely help it to attain it.

The third auxiliary theory to natural selection,
germinal selection, may also be described as a
teleological principle. In the first place this hypothesis
supposes that the germ has a purposive faculty of self-
correction, controlling the advancing and retreating
movements of the determinants in most cases. But
purposive forces within a determinant must above all
things prevent too unequal a nourishment of the various

1 We have already shown on p. 82 that female choice seeks to attain
an end.

372

DARWINISM AND THE PROBLEMS OF LIFE

biogens that compose the determinant. Irregularity in
the nourishment of the biogens of a determinant would
alter their quality. But why does the unequal growth
of the biogens, owing to irregularities of nutrition; never
disturb the harmony in the determinant, as is the case
with panmixis? In fact, the harmony of the parts
should be far more profoundly disturbed in the deter-
minants than in degenerating organs. In the latter
case the controlling influence of natural selection never

entirely ceases, while irregularities in the food-supply of
the determinants can never be controlled by natural
selection, as they only give occasion to selection to come
into play when they give rise to variations : in other
words, they always precede selection. Hence when we
see, for instance, that the determinants of a bird’s feather
are almost never modified in such a way as to produce
scales or other malformations instead of a feather, we
must assume that there is a purposive force in the
determinants also that ensures the harmony of the
biogens.

But our task is not completed when we reject the
teleological auxiliary theories from natural selection in
order to have a purely mechanical principle. Teleolo-
gical phrases and terms are only too easily slipped into
the theory of selection itself. In fact, we ourselves
have not been quite exact in our expressions in the
nine preceding chapters. We had to do this so as not
to confuse the reader by using unfamiliar phrases. The
teleological always comes more naturally to us than

'

1

tl;

THE MECHANICAL SYSTEM AND ITS LIMITS S7 3

the mechanical, as we are accustomed to looking for
ends and purposes. But as we have given only-
mechanical processes in the character of facts, we need
now merely rectify our form of expression.

In the first place we must give up the term
“purposive.” There can be no question of “purposes”
in a scientific investigation. We can only speak of a
structure in an organism as purposive in the sense that
the animal has the faculty of self-preservation in its
momentary circumstances.

We must also be careful in using the word “evolu-
tion.” When we speak of the evolution of the animal
world, the thought involuntarily forces itself on us that
they have advanced from lower to higher forms. But
we have no right to speak of “lower” or “higher”
forms. We should in that case have to suppose that
there was from the first a principle in the living
substance that gradually creates the higher forms, and
we have rejected that view. By higher and lower
animals we can only mean more complex and sivipler.

Natural selection is not a principle of progress, always
creating higher animals. Selection merely seeks to
adapt organisms better to their environment. But
greater complexity of organisation has no relation to
good adaptation. We pointed out previously that man
is not better adapted than the bacillus. From the
point of view of the birds man must be a very
imperfect being.

If greater intricacy of structure were the same thing
as better adaptation, natural selection would gradually

374 DARWINISM AND THE PROBLEMS OF LIFE

have to give all animals a complex organisation, since
it always seeks the better adaptation of all animals.
But we still have protozoa living in a drop of water.

In fact, many highly organised animals have become
extinct, while their more simply constructed relatives
have survived.

There may be occasions in which the more complex
organisms are at a disadvantage in comparison with the
simpler. Natural selection will then modify organisms
in the direction of greater simplicity. In our view of
the development of the earth there will really be such
a time one day. The water on our planet is constantly
decreasing, and the time will come when there will not
be sufficient left to support human life, when the bones
of the last man will bleach in the unclouded glare of the
sun. But in the last drops that will linger in holes in
the vast desert of the earth there will certainly still be
infusoria. After a time even these creatures will not
find water enough ; they will perish, and only simpler
organisms still will be maintained, until at last all living
matter has returned to its mother and changes into
lifeless mineral once more.

The fact that there are to-day animals at such
different stages of organisation is due, as we now know,
to special accidents that isolated certain animals. Even
the step that seems greatest to us, the formation of
multicellular organisms, must have taken place at a
particular locality — whether it was that certain protozoa IB
reached running water and so the connected ones were 3
less easily washed away, or that they reached a pond

THE MECHANICAL SYSTEM AND ITS LIMITS 375

that was poor in oxygen and could only make a
sufficient use of the oxygen by sticking together. The
imagination has a wide field in these problems, but we
cannot say whether the construction of multicellulars
only took place once or on several occasions.

As natural selection is not a force that of itself creates
more complex organisms, so it is not an absolute
principle of progress. It is scientifically illogical to say
that animals are “ improved ” by natural selection.
“Good” and “bad ’’are antithetic and dualistic terms
that have no place in a unified conception of the world.
The word “ improve ” would only have a meaning if we
recognised any value in the nature of animals. But
that is entirely wrong. The man of science has only to
determine the processes of the world and discover their
causes. For him there are only changes in the world.
There can only be an “ improvement ” if we recognise
an end, the good. Mechanism has nothing to do with
ends.

Even if we could recognise value in the nature of
animals, we could never say whether certain changes
that we observe in animals are improvements or no.
Selection adapts animals to their environment at the
moment, and we do not know if these will not change,
in which case the opposite modifications will have to be
selected. For instance, if the animals with the thickest
coats survive in a very cold climate, we cannot say that
the selection of the thick coat is an improvement for
the animals. If that were so the cold would have to
remain unchanged, whereas the climate may become

37^ DARWINISM AND THE PROBLEMS OF LIFE

warm again. If it does the animals with the thinnest
coats will be in the best position.

When we reflect on the past history of animals and
find that a long time ago thick-coated animals were
selected because the cold persisted, we cannot even
then speak of an improvement. We have not to consider
the chains of cause and effect in relation to what they
eventually lead to, as that would be teleological. We
have to look on each change only as the effect of a past
cause. When we are studying the past, we must leave
the present out of account. It would be unscientific to

predict the persistence of the cold.

• • • • • • •

We have now purified the theory of selection of all
teleological elements and prepared it for incorporation
in Mechanism. We may now return to the question
from which we started, and ask if Mechanism gives us
a satisfactory explanation of the world and how it does
so. We have to examine its method, and as this is at
the same time the method of all natural science — in
its higher forms — we shall learn to appreciate scientific
method generally.

We have already seen that it is the infinity of the
world that prevents the human mind from comprehending
it. We will now go more fully into the point.

When the man of science approaches the object of his
investigation, the world, he feels himself surrounded by
a bewildering wealth of forms that he can never compass.
The corporeal world is infinite in its variety and
inexhaustible. No-one thing' is like another ; everything

THE MECHANICAL SYSTEM AND ITS LIMITS 377

represents an object that can never be entirely replaced
by another. Quite apart from the incalculable distance
of the stars, one cannot even count in detail the bodies
contained within a limited space. No stone is quite
like any other, no tree like another, no leaf, indeed,
exactly like another. It is, therefore, quite impossible
to describe every single thing in the world.

But even when we abandon the idea of grasping the
whole universe, and turn to the study of a small part of it,
we encounter insuperable difficulties. Every part of the
world, no matter how small, has so many differences
latent in it that they cannot be counted. The more
thoroughly we study a single body the more vast do we
find the number of differences in it. If we continue to
analyse a body, we bring to light at each analysis new
things that were unknown to us. And as each surface
has its colour, and this always differs, we can never
exhaust the shades of colour of even the smallest
surface.

This enormous diversity in nature not only prevents
science from comprehending the world, but no human
being could orientate himself in the world if language
did not come to his assistance. Language enables the
human mind to take in a large number of details by
imposing the same name on them all. The whole
infinitely varied population of the earth, differing in
each individual, can be grasped by the term “man”; so
those predatory animals of the forest, not one of which
is quite like another, by the term “wolf.” We gather
together all the objects in inorganic nature by means of

37$ DARWINISM AND THE PROBLEMS OF LIFE

names, just as we take certain metals of which there
are only pieces that differ in size, shape, contour,
and colour, under the name “iron.”

How is this comprehension of individually different
bodies possible ? By regarding only that which objects
have in common and overlooking the individual features.
When, for instance, we give the name “gold” to a
large number of objects, we look merely to the common
brilliance, the colour, and the weight, and do not take
account of the difference of the pieces of gold in size,
angles, surfaces, etc.

Science continues the work of language, as it were.
It brings together a number of bodies by regarding
merely what they have in common. In this way it
creates scientific concepts. A certain number of the
countless particular things in the world, which have
certain common features, are “conceived.” But science
has something further to do. It must give definite
formulae to its concepts, so that we may know what
is the common element in the particulars that the
concept embodies. That is done by a number of
propositions or judgments. The scientific conception
must always be capable of conversion into judgments.
Judgments of this kind on the concept “diamond,” for
instance, would run : transparency, refraction, hardness,
definite angles of the surfaces, etc.

A good deal is accomplished by these concepts.
Large numbers of diverse things have been made
comprehensible. But the number of these concepts,
in turn, is immense, and science would have done

THE MECHANICAL SYSTEM AND ITS LIMITS 379

only half its work if it were content with these. There
must be subordinating concepts, expressing the common
element in a certain number of concepts. Thus gold,
silver, iron, and other minerals are grouped together as
“metals.” As science extends its range, and looks to
the common element in the subordinating concepts
themselves, it seeks at last to pursue its method to
a point where it is impossible for direct observations to
determine the common features. 1 hus we not only
conceive the seventy elements to consist of homo-
geneous atoms, but also that these seventy different
kinds of atoms are at bottom composed of the same
particles, or primitive atoms [such as electrons]. The
diversity in the structure of the elements is due to a
difference in the grouping of these in the atom of the
element. Hence the ultimate particles make up the
whole material world. They are the common element
in all matter.

Not only the bodies, but also the phenomena, in
nature are infinitely varied. When we speak of
“storms,” we are grouping together a large number
of different phenomena, with respect to the common
feature in them. Phenomena also are grasped by
science through general concepts, which express the
common element in them.

However, these concepts require something further.
They must be free from space and time, if they are
really to embody all that has happened, is happening,
or will happen, in the world. They must have a
universal application, because it is only then that they

380 DARWINISM AND THE PROBLEMS OF LIFE

can express an infinite number of phenomena, and it is
precisely infinity that has to be overcome by the
formation of concepts. We can, of course, only form
our concepts in a limited number of instances, but we
must make them capable of expressing all phenomena
of the kind ; they must apply universally. To the
concepts which take the form of judgments and apply
to certain phenomena of all time we give the name of
natural laivs. A natural law embraces an infinite
variety of particular processes, and embodies what it
is important for us to know in them.

Just as a large number of concepts of things are
arranged under one comprehensive object-concept, so
we find in the case of law-concepts, or natural laws.
In the end science comes to formulate one ultimate law,
which embraces all the phenomena of all time. The
other laws are only special cases of this law.

Thus the final outcome of science is the formulation of
an ultimate object-concept, which is common to all bodies,
and an ultimate natural law, that embraces all pheno-
mena. When that is accomplished, the infinite diversity
of the world is overcome. We have then no longer to
grasp endless series of causes and effects ; we merely
' conceive the one law that dominates the whole series.
Our mind no longer needs to arrange in itself the incal-
culable number of different bodies and occurrences — a task
it could never accomplish ; it has now to deal with one
body and one phenomenon. Thus the infinity of the world
is mastered. We can now make all the bodies in the
universe intelligible at any time by means of a certain

THE MECHANICAL SYSTEM AND ITS LIMITS 38 1

combination of ultimate things ; in other words, we can
express all bodies in arithmetic formulae. Numbers are
always comprehensible ; they have no particular features
in themselves, and so lack the diversity of forms that is
found in reality. We know, especially, that we can
count in a series as long as we like, and we will never
come to anything essentially new. Like bodies, we can
also represent all phenomena by certain arithmetic
formulations of the one law, which is all we have to
grasp.

But this comprehension of the world will only be
possible if the “ ultimate things ” are fundamentally
distinct from the bodies that we know. All the objects
known to us change. Each of these changes passes
through an incalculable number of stages, and the
ultimate things, which must be calculable, cannot be
changeable. They must not be transitory. They must
also be indivisible , as all division is change. Finally,
they must be exactly alike in size and quality. Each
ultimate thing must be capable of being replaced by
another without the least change taking place ; other-
wise they cannot be used in mathematical formulae.

Mechanism endeavours to realise this ideal of know-
ledge. There is only one thing that is common to
all others and enters into the composition of all that
begins to exist — ether. There is only one law that
embraces all phenomena — the movements of ether.
Ether is a space-filling but imponderable medium, con-
sisting of minute particles, which are simple, immutable,
indivisible and homogeneous. All the phenomena in the

382 DARWINISM AND THE PROBLEMS OF LIFE

world, electricity, light, and the rest, are special forms of
ether-movement; even matter is to be regarded as an
ether-movement, since the ultimate particles that make
up all bodies are centres of condensation in the ether.

It is the task of science, therefore, to determine the
various categories of ether-movement, and to express
light, electricity, and even matter in mathematical formulae.

Will it ever be possible to analyse bodies so finely as
to bring the ether-particles to light? No. Apart from '
the fact that every portion of a body must be itself a
body, not incorporeal ether, the latter entity has no
features of reality. In the reality that surrounds us
there are only divisible and transitory things, of which
no one absolutely resembles another. Each body, how-
ever small, has its individuality ; this becomes all the
clearer the more thoroughly we study it. Thus the
apparently similar grains of sand betray their individual
differences under the microscope. But the ether-
particles cannot have individual characteristics, and
so they are quite unimaginable. The world speaks
to us through all our senses with its infinite character-
istics , 1 and we cannot picture to ourselves bodies with-
out properties, such as the ether-particles must be.

1 Thus the ether-particles explain phenomena and matter. But the
ultimate elements of matter also, the primitive atoms, are something
unreal, because they must be absolutely identical, and because no
further body can be produced by subdividing them. In fact, the
atoms themselves cannot have individuality. But we know that there
cannot be anything that is not individual, and that no body is
absolutely identical with another. We must, therefore, regard even
the atoms only as a device of knowledge. We see here the value of
such a contrivance. Chemistry has made marvellous achievements
precisely through its atomic theory.

THE MECHANICAL SYSTEM AND ITS LIMITS 383

They are in contradiction with the reality that we
know.

It has been said that when we exhaust the air under
a glass-bell and the light remains in it, we see the
vibrating ether. But it has been rightly answered that
even then we do not see ether, but light alone.

There is no ether, because there is nothing in the
world without properties. Ether can never be the
object of research ; it is only a means of understanding
the world.

We come to the following important conclusion.
Natural science does not represent reality to us as it is.
Reality, as it reveals itself in the world, is absolutely
incomprehensible to any science or any human being,
because it is infinite. Science cannot deal with it as it
is ; it has to transform and simplify it. It does that at
the very outset of its work. Its first concepts do not
picture reality, but apply to it ; this is done by leaving
out of account a part of what distinguishes reality — the
individuality of each particular thing. As this work of
transforming to render intelligible proceeds, and more of
the individual characters fall out in the higher concepts,
science departs further and further from the visible
reality. Its ultimate concept, which has to embrace
all, and so must have nothing individual about it, can
have nothing in common with reality. It is not a
reality, but an indispensably necessary means for grasping
the whole world.

Natural science is occupied with bodies, and forms

1

384 DARWINISM AND THE PROBLEMS OF LIFE

its concepts on these, so that they exclude anything
incorporeal. Hence it has nothing to do with psychic
phenomena. These can never be understood from the
observation of bodies and their processes, because the
corporeal can never explain anything but the corporeal.
Science canj never tell us how the simplest sensation
comes about. Even if we had an exact knowledge of
the mechanism of the brain, even if we knew all the
movements of the atoms in feelings of desire and pain,
we should only be witnessing the movements and shocks
of bodies. It is true that the sensations are connected
with these, but they tell us nothing about the origin and
nature of the sensations. Being incorporeal, the sensa-
tions lie beyond our range of observation.

The psychic processes are dealt with by psychology.
This science, again, is confronted with an infinite variety.
No one can dream of picturing to himself all his pains
and pleasures, his ideas and judgments. Each psychic
process occupies a certain time, and so passes through
an incalculable number of stages.

In order to master this diversity, psychology forms
concepts in relation to the universal in the particular
psychic processes. It endeavours to find the elements,
or the simplest constituents, of the psychic life, of which
we must conceive all the psychic phenomena to be
composed. “ Sensations” have been advanced as these
elements, and it is said that the will and the ideas, in
fact, all the psychic processes, are made up of these
elements. But experience knows nothing of “sensa-
tions ” that may constitute such diverse processes as a

THE MECHANICAL SYSTEM AND ITS LIMITS 385

will and ideas. Hence in this sense the sensations are
merely scientific devices, like the ether-particles of the
physical scientist.

We saw that Mechanism has accomplished its task
in making the world intelligible to us. Psychology
makes a similiar effort to solve its problem, but, being
a younger science it has not achieved nearly so much
as physical science. We may now ask whether it is
not possible to bring together the ultimate concepts of
both these worlds, and so attain a perfectly unified and
harmonious knowledge.

We have rejected the opinion of the materialists who
hold the psychic processes to be the object of physical
science. Can we say the reverse of this ? Does not
the corporeal world consist of psychic processes ?

The reader who has never reflected on problems of
this kind will think the very question is an absurd one.
We are accustomed to regard the world about us as
existing quite independently of us. But that is certainly
not the case.

All our knowledge of the material world comes
through our senses. But all that passes through our
senses can only give us sensations. The various
properties that make up the complete image of a body
are merely so many sensations within ourselves. A
piece of gold seems to be a body, but this body is
made up of the sensations of yellow, hard, heavy, cold,
etc . 1 It is the same with all bodies. Hence men in

'These sensations, of course, must not be confused with the psychic
sensations that make up will and ideas in the sense described above.

2 u

3B6 DARWINISM AND THE PROBLEMS OF LIFE

whom one sense is missing have a totally different idea
of the world from ourselves. If the missing sense is
restored to them by an operation, they can hardly
recognise their world with it. A blind man whose sight
has been restored cannot recognise the bodies about him
until he has touched them.

Sensations give us information of the external world
when they reach our consciousness. How often do we
not look at our watch without noticing the position of
the hands, or touch an object without perceiving its
existence ! When we are asleep the world has ceased
to exist for us.

When other men tell me that the world continued to
exist while I was asleep, their movements and voices
create nothing in me but sensations, and of these I only
know what reaches my consciousness. Even my own
body is only known to me by processes of consciousness;
when I am not conscious of it, it does not exist for me.

There is no sense, no reality, in the world that we
can bring into opposition to consciousness. There
is nothing that is not a content of consciousness. That
is a truth that cannot be shaken ; in fact, it seems to be
the eternal immutable foundation of the clashing
structures of theories about knowledge. All that we
experience and live, all that we see and feel, consists
of conscious processes.

Here we refer to ordinary, individual sensations, familiar to everyone
under this name. We shall not go into the question whether there are
conscious and unconscious sensations. When it is said that the sensa-
tions must reach our consciousness, we are merely following the usual
form of speech.

THE MECHANICAL SYSTEM AND ITS LIMITS 387

This is not the place to treat the question whether
the processes of consciousness bring the external world
before us as it really is, or whether this real corporeal
world, the “thing in itself,” is not something quite
different from what we imagine ; whether it does not
merely set our conscious processes in motion without
revealing itself. Or whether in the end conscious
processes can only be evoked by other conscious
processes ; whether there is no external world corre-
sponding to them, and its causes and effects only exist in
our thoughts. These questions would lead us into
endless controversies. We have only raised the point
to see whether Mechanism can be reconciled with
psychological science, or whether it dissolves in it.

That is not the case at all events. The material
world is a process of consciousness, it is true, but so are
the psychic phenomena. We may make it clear in the
following way.

The material world can only be conceived as a content
of consciousness. Consciousness is, as it were, the
subject and bodies are the objects ; that is to say, the
bodies are the objects to be known and consciousness is
the perceiver. But my consciousness perceives not
only the bodies apart from my own body, but also this
itself ; it may even become an object of knowledge itself.
But that is not the whole function of the knowing
subject. My whole psychic life with all its processes may
become the object of the cognitive faculty of conscious-
ness, otherwise there could be no psychology, which
needs objects to investigate. Thus we see that

388 DARWINISM AND THE PROBLEMS OF LIFE

consciousness encloses in itself not only the whole
corporeal world, but also the whole life of the soul.
This cognitive power is devoid of all personality. But
we cannot suppose that the all-embracing, impersonal
subject, which enfolds the whole of existence, appears
in isolation ; for us it is always connected with a part of
the psychic life. In this sense one might call psychology
a higher science than physical science. But the reason
is merely that we cannot study the whole of the psychic
life simultaneously , and make it the object of knowledge.
However, we will not go any further into this difficult
question.

We have seen that reality contains two separate pro-
vinces, the material world and the psychic life, nature and
mind. Either province may become the material or the
object of science, and the scientific method may be
applied to either — the method that enables us to grasp
the enormous diversity of objects by grouping many of
them together with respect to their common features.
As the two sciences proceed to form more and more
comprehensive concepts in this way, each of them comes
at length to the ultimate and all-embracing concept —
ether for the material world and psychic sensations for
the spiritual world. In this way physical science and
psychology put the keystone on their respective
structures, and have then to elaborate and develop
their systems in detail. To throw light on and
reconcile the two ultimate concepts is the task of a
new science, which has to bring reality into unity
without taking into account the antithesis of body

THE MECHANICAL SYSTEM AND ITS LIMITS 389

and soul. It is consciousness that encloses in
itself all existence, the material and the spiritual
world, since both provinces can only be conceived as
processes or states of consciousness. In consciousness
we have a unity and a truly “ monistic ” stand-point.
But consciousness, the all-perceiving subject, can never
become the object of an empirical science. When we
wish to study it, we have to leave aside the scientific
method and turn to philosophy. This is the last

and the highest science. It is the foundation on
which every theory that aims at comprehending reality
must rest. It is the undying merit of Immanuel Kant
to have shown us the way to it.

CHAPTER XII

NATURE, HISTORY, AND ETHICS

Truth of scientific ideas. Why the universal seems to us more
essential than the individual. The ideas of animals. Why we
take ideas for realities. Thinking reality into ideas. Is there
a real world, lying behind the phenomenal world? Natural
science itself is a human product and pursues an aim. It must
not regard itself as the only sound branch of science. The
historical sciences. Their method. The historical elements in
natural science. The laws justify historical research. The science
of evolution rests on probabilities. The origin of the human
mind. Had consciousness a beginning ? There never were
absolutely simple bodies. History and sociology. Origin and
development of primitive man. Origin of good and evil. Origin
of conscience. Advance of civilisation by tradition. Language.
Conflict of nations. Scientific ethics. Restricted and inverted
selection in civilisation. The evils of war and militarism.
Nietzsche’s egoism. Darwinian ideas of the social future.
Insipidity of the Darwinian ideal. Social man according to
Nietzsche. Natural science knows no idea of duty. It knows
nothing of values, and can therefore frame no ethic. Preservation
of existence is not preservation of value. Is there a sense of
life? Monism. Presuppositions of science. The idea of duty
is the beginning of all knowledge. Conclusion.

The world is infinite and immeasurable, and no science

will ever be in a position to describe it. Science would

not yet have accomplished anything if its work had

merely consisted in describing or picturing the world.

It could only attain to a knowledge of the world by

transforming reality and simplifying it so as to make it

39 °

NATURE HISTORY, AND ETHICS 39 1

intelligible to the human mind. But it follows from our
theses that reality is infinitely varied on the one hand,
and that scientific theory stands higher in proportion to
its simplicity on the other, or that scientific theory is the
more perfect the less reality it reflects in its concepts.

This statement in no way diminishes the importance
and objectivity of science. Although the scientific
concepts are not pictures of reality they are very closely
related to it. There cannot be any unscientific
arbitrariness in science because its concepts are
universally valid. They are unconditionally true , not
because they depict reality but because they apply to it.

How is it, then, that it is not obvious to everyone
that ideas do not correspond to individuals ? How is it
that so many people think there is some reality
corresponding to the idea “ wolf,” whereas the idea has
only been found by the mind transforming the reality in
order to grasp it ?

It is because, in the first place, man’s senses have
only a limited power of discrimination. Widely
differing objects often seem to us to be alike ; even on
closer examination we often see only their common
features, and do not see their individuality until we look
carefully for it. Many bodies, such as grains of sand,
seem alike to us however closely we examine them ; it
takes a lens or a microscope to show that not one of
them is absolutely similar to another. But that our
senses perceive common features first and foremost, and
that our intelligence always recognises first the common
features of the objects about us, is clearly a faculty that

392

DARWINISM AND THE PROBLEMS OF LIFE

we owe to natural selection. How could we orientate
ourselves in the world if every single object about us
were something peculiar and had its special name? We
should have to describe and count so much that we
could never make ourselves known to another ; he would,
in fact, never have a clear idea of the body we were
speaking of, unless we could bring before him a number
of bodies which are familiar to him in their common
features. There would be no language if there were no
general terms.

We must assume that the nerve-centre that receives
a sense-impression was so constituted from the first, even
in the animals, as to perceive especially the common
features. The fox must have general ideas of “ hare ”
and “ man,” in order to know which to pursue and which
to flee. If all things appeared to him to be unlike each
other, everything he met would be something new, and
he would not know how to act in relation to it.

The simpler the life of an animal is, the less advanced
are its senses and the more comprehensive its concepts.
For the frog there are only “ stationary ” and “ moving ”
things, and of the latter only “large” and “small.
The former it avoids, the latter it pounces on.

The development of an animal’s senses is always in
proportion to its habits of life. Hence there are
animal senses that can detect the individual better than
the corresponding sense in man. Take, for instance,
the dog’s sense of smell. As a general rule animals
recognise individual realities better the more advanced
their senses are. Man has created devices for improving

NATURE, HISTORY, AND ETHICS 393

his senses, optical instruments, which enable him to
detect the special features even in the smallest bodies.

However, common features always come much more
naturally to man’s perception than special ones, because his
senses are adapted to them. Thus it seems to him that the
general features alone are essential, and physical science
is thought to be the most natural of all sciences because
it starts from the proper nature of the sense-impressions.

Hence in order that man may orientate himself in the
world, numbers of things have to be brought together
in virtue of their common features and provided with a
common name. And as most things have not a very
great interest individually, because this is not necessary
for the purposes of human life, they generally have only
generic and not proper or individual names. When we
speak of the individual we have only the generic name
— “ wolf,” for instance — and so this name or concept
seems to us really to coincide with the individual in
question.

But there are also things in the world that have an
individual interest. They have generic names, but also
proper names, and in this case it is clear that the con-
cepts are not perfect images of the individuals. We
see this especially in the case of man. If we try to
express the individual “ Shakespeare ” by the idea
‘ poet or “ man, ’ we see at once that these ideas do
not represent the great poet, and do not embody pre-
cisely those features that make Shakespeare Shakespeare.
When we say “ poet ” instead of Shakespeare we are
really doing just the same as when we say “ wolf” of a

394 DARWINISM AND THE PROBLEMS OF LIFE

particular wolf, or when we express a certain plant or a
certain piece of gold by the corresponding concepts.
There are also stones that have an individual interest,
and here again it is clear that they are not fully
expressed by their generic ideas. Take, for instance,
the diamonds Orloff, Star of the South, or Kohinoor.

The concepts are not definite pictures, because they
do not mirror reality ; but we think this into them,
and thus they appear to be pictures. When we speak
of wolves, we always think involuntarily of a particular
wolf. When we say “ man,” we think of a particular
man — with a medium-sized, straight nose and other
definite features, just as when we make sketches of
the objects.

Thus the reality is always forcing its way into our
narrower concepts, but it does this less in the case
of those with wider range. It must be difficult to
imagine a “vertebrate” — impossible, if one has never
seen one. Try to form a mental picture of an
“animal,” without thinking of the features of the
protozoa, worms, insects, birds, or other organisms.

Thus we see that the concepts are less definite and
depart more from the reality the “better” or more
comprehensive they are. The ultimate concepts, that
embrace everything, cannot become mental pictures ;
there is nothing of reality in them.

It is true that when we think of “ether,” we picture
to ourselves tiny balls, pushing and attracting each
other, and in a state of perpetual motion ; such an idea
enables us to grasp a mechanical process in the world.

NATURE, HISTORY, AND ETHICS 395

But we must never forget that when we do this we
think something into ether that is really not in it. The
ether-particles cannot be balls, otherwise they would
differ in size and be divisible ; they would, in fact, be
bodies with the properties of bodies, and that is just
what we must avoid. The ether-particles must have
nothing individual about them, and therefore they are
unimaginable, and have nothing in common with
reality; they lie behind reality, and are metaphysical.
Their movements also are unimaginable, as we can
only picture to ourselves movements of bodies ; we
know no such thing as movements of incorporeal
things.

But, it may be objected, is not reality only apparently
individual ? Is there not, behind the reality that we see,
something that represents the true reality ? And may
not this be simple and non-individual ? If that were so,
it would be the task of science to pass from the apparent
world which we see to the true homogeneous world
beyond.

But such a statement has little value, since no one
can prove it. On the contrary, it is highly improbable.
The commencement and the advance of the scientific
formation of concepts is — as no one will question — an
artificial modification of reality. Only the individual
exists, only that appears at a definite spot, is never
repeated, and is gone for ever once it is destroyed.
When the human mind brings together a number of
these bodies, by looking only to their common features,
it has no idea of picturing them altogether. How could

396 DARWINISM AND THE PROBLEMS OF LIFE

it happen that after forming higher and higher concepts,
depicting less and less of the things comprised, suddenly,
when the whole thought-process was over, the “ ultimate
things ” once more contained the complete reality ?
When man began and continued to form concepts, he
regarded the world from which he started as the sole
reality ; he by no means sought after a “ metaphysical,”
true reality. It would be a piece of good fortune that
we would have to put down to magic if at the
conclusion of his process of thought the final result
represented the true and different and hitherto unimagined
reality.

No, it is incredible. We must assume that science,
which ever presses on, and must press on, towards
greater simplicity, and so is always analysing bodies
afresh without ever coming to an end, imagines the
process of division to be complete. In that case we
need not assume that in the continued disintegration of
bodies we shall come at length to parts that are not
bodies. We shall then see that the ether-particles were
created by the human understanding, because it needed
them in its effort to understand nature.

Physical science is described as empirical, and the
designation is correct. But we must not on that account
suppose that science never goes beyond the range of
experience. It deals with probabilities as well as exact
observations. When it deduces a “law” from a
number of phenomena that it has observed, it assumes
that this law will hold also for other phenomena of the
same category ; and this assumption in turn implies

NATURE, HISTORY, AND ETHICS 397

that there are general laws which apply universally and
unconditionally. This, of course, can never be proved.

It is possible that new observations might be made
that compel science to rearrange all its laws. However
that may be, physical science is not absolute and

i

unconditional, because it supposes that what is true in
a thousand cases will not prove untrue in the next one . 1

Thus science is influenced by considerations that do
not arise of themselves from reality ; it is also a product
of the human mind, and endeavours to achieve its task
of making reality intelligible. Hence physical science
has no right to oppose other sciences which modify

reality in order to attain their ends.

• • • • • • •

The concepts which are formed with regard to the
universal alone cannot contain the particular. As the
laws of physical science deal with what applies always
and everywhere they cannot answer the question, what
exists at a particular point of space, what happens in
detail, and how that which exists came into being.

These questions are dealt with by the historical
sciences — or history, in the widest sense of the word.
Physical and historical science complete each other.
Hence we find scientific elements in history and
historical elements in science.

The historical elements increase in physical science
in proportion as its ideas approach reality and depart

1 The laws of science must not admit a single exception. In their
case the law is not confirmed, but completely destroyed, by the
exception.

39& DARWINISM AND THE PROBLEMS OF LIFE

from individual things. There is absolutely no historical
element in the idea of ether, because even if it
represented something real it would be useless to
raise any historical question about it. Every ether-
particle must contain just the same as the others, and
so it is absurd to seek the particular features of one
of them.

However, even in scientific concepts which are
very comprehensive, but not all-embracing, there are
historical elements. The sciences that deal with these
concepts start, in a sense, from a historical fact. Optics,
for instance, treats of light. But if we have had some
experience of light, we always think of the light we
know in that way. If there were anyone who had
never seen light, he could form absolutely no idea
of its real nature, no matter how accurately he knew
the figures and formulae that represent the vibration
of ether when it causes light. The further question
arises, moreover, when and where light came into
existence. Such questions cannot be settled by the
methods of physical science.

We could show in greater detail how the historical
elements in natural science increase in proportion as
the various parts of the total science decrease in com-
prehensiveness. But we have not space to do this,
and will be content to consider the sciences that deal
with life.

The problem with which we are concerned, the
origin of species, is of an historical character. It is
a question of a process that once took place. Hence

NATURE, HISTORY, AND ETHICS

399

when we seek to determine this process of evolution
in detail we have to use a different method from that
of physical science. We must act on the historical
method. In point of fact, we rely on documents, as
the historian does. They share the character of all
documents of being less valuable the more remote
they are . 1

It is not our purpose here to study the principles
of the historical method. The historian is equally
unable to represent the incalculable diversity of reality.
He must select definite points. He will choose
particular events — or, as every individual thing is
itself too vast to comprehend — certain particular
events.

1 The objection is raised that Professor Haeckel has been
endeavouring for some forty years, with very moderate success, to have
the natural sciences called “historical" instead of merely “descriptive" ;
in other words, that it is the chief part of their task to tell us, not the
actual nature of things, but how they became what they are. The
reader who has followed me so far will see for himself the error of this
objection. In the first place, ether can never be studied historically,
because it had no origin. Anyone who' takes up a manual of physics or
chemistry will see that in these it is nearly always a question of what
the law is — what is valid independently of time — not what has come into
being. There are, of course, historical questions in these sciences, but
very rarely; their investigations are almost always purely scientific. On
the other hand, zoology and botany use both methods. In my contrast
of the two methods, I aim merely at a logical appreciation of them; I
am not bringing into opposition sciences that differ according to
their material. I merely say that all our sciences may employ both
methods, but that one finds the one method more suitable, another the
other method. The first method determines what holds good indepen-
dently of all time, by discovering the common element in phenomena ;
the second determines what has taken place once, regarding, not the
common but the individual features, and interpreting it according to
the documents. The two methods are, therefore, of a precisely
opposite character.

400 DARWINISM AND THE PROBLEMS OF LIFE

The historian first chooses his theme. This is
usually a fact or event that interests him and seems
worth study. He then examines the antecedents of
this event, and selects those that have a bearing on
his subject. Thus a student who is writing a history
of the preparatory period of the Reformation will not
speak of fashions in dress or the price of food, but will
confine himself to the points that have some relation
to the Reformation. Again, the evolutionist who is
studying the origin of the vertebrates will only
describe those of the innumerable changes in the
animal world that may be regarded as stages in the
formation of the vertebrates. That is not an
unscientific procedure — not teleology in the sense we
described above. The historian neither forces the
chain of causes towards his aim, nor fancies that they
sought this end from the first ; he merely studies only
those meshes in the network of causes and effects that
lie before the phenomenon whose origin he is investi-
gating. This way of studying it arranges agencies in
a straight line, and makes them seem to be aiming at a
certain result.

The evidence for the evolution of animals differs
from that we consult in human history. Most of it
is of such a character that we have first to justify our
action in regarding it as evidence. This justification
is furnished by the laws of science. The law which
says that organisms are constantly changing, and that
every living thing descends from some other one, gives
us the right to regard the remains of the different

NATURE, HISTORY, AND ETHICS 401

animals of earlier ages as the ancestors of living
animals, and to determine the historical lines of
development. The law which says that animals
resemble each other in proportion to their blood-
relationship gives us the right to take their structure
as evidence of their ancestral history. And there are
still other laws.

However, these laws only justify historical investi-
gation ; they do not supply the place of it. They
apply wherever there are organisms, and therefore they
cannot discuss the particular process of the modifica-
tion of a species. A law that has only held good in
one particular case is an impossibility, because every
law is formulated by regarding the common element in
a number of phenomena. Hence the laws of science
can never bridge over the interval between two
distinct stages of organic evolution ; indeed, one
might be acquainted with all the laws that apply
to organic evolution yet have no idea of the real
course of this development.

The laws can never tell us, for instance, how birds
were developed from reptiles. Again, if there were
a law which said that in the rise of a nation there
were always great men who led the people, we should
not understand from this law alone why Luther in
particular appeared at the Reformation, or Bismarck
at the rise of modern Germany, and why these
special individuals led the people.

It is in the very nature of the evidence for animal
evolution to be grounded on greater or less probabilities.

402

DARWINISM AND THE PROBLEMS OF LIFE

On that account we shall always find differences of
opinion as to the value of the historical investigation
into the transformations of animals. There are recent
zoologists, for instance, who would confine their science
to the establishment of laws, and would reject all
“ galleries of ancestors ” as not affording any
explanation.

But that is a one-sided and unjustifiable appreciation
of science. Even probable transformations in the
organic world are certainly very interesting. As long
as man reflects on himself, he will long to know some-
thing of his earlier history. Every discovery will be
welcomed that throws light on the obscure condition
of primitive man.

In the nine preceding chapters we have made
simultaneous use of scientific and historical methods
of research.

We have, on the one hand, investigated the common
features in the particular evolutions of living things,
and thus formulated laws. The most comprehensive
law that we discovered was that those organisms
especially survive which are best adapted in their
structure to their actual environment . 1 This is the
principle of selection. We found that it holds good
wherever there are living things. We next tried to
prove that other laws of evolution do not hold. We

1 Natural selection is a law because it presents the common element
in all evolutions, and it applies wherever there are organisms ; but it
differs from other scientific laws in not definitely presenting the common
element. It has to use the qualifying clauses “on the average,” or
“as a general rule.”

NATURE, HISTORY, AND ETHICS 403

therefore concluded that it must be the sole agency
that effects the modification of animals.

On the other hand we sought to determine the
particular processes of animal evolution by means of
historical inquiry. For this purpose we used such
evidence as the structure of animals, fossil remains, and
so on. We were given the right to do so in virtue of
natural laws. In this way we succeeded in determining
the period — if only approximately — and the locality in
which a certain modification of animals must have taken
place, and to some extent we were able to follow the
course of this transformation.

The provinces of natural science and psychology are
entirely distinct, as the one forms its concepts on
phenomena that occupy space and the other does not,
but the distinction does not hold in regard to historical
investigation, Bodily and mental phenomena are in
time, change, pass through stages, and are individual.

As we have adopted the view that man has animal
ancestors, we must trace his mind also to them, though
it is at least a lower stage of development in the animals.
We saw in the second chapter that, as a matter of fact,
man’s mental processes are found in a more rudimentary
form in the animal.

As we cannot admit that the mind is formed in any
animal out of nothing, we must ascribe psychic phenomena
to the protists. We must even go further. We have
accepted the view that living things were developed
from inorganic matter. Did psychic phenomena begin
at once with the appearance of living substance ? That

404 DARWINISM AND THE PROBLEMS OF LIFE

is scarcely possible. Living matter, we believe, evolved
from lifeless. But the psychic processes cannot have
developed from it, because we know that bodies alone
can be formed from bodies, never anything spiritual.

Thus we are forced to ascribe psychic phenomena
even to inorganic matter. Why they are not recognis-
able in it, or why they are so different even in the lowest
animals, it is impossible for us to say. They are subject
to transformations which become so considerable in the
course of long ages that something entirely new seems
to have come into existence. That is all we can
say.

But this process of transformation only applies to the
psychic processes, not to consciousness. It is absurd
to conceive consciousness as evolving from material
things, and as having any beginning at all. We know
that we cannot imagine anything either corporeal or
spiritual, anything real at all, that is not a content of
consciousness. Time and space exist only in conscious-
ness. How, then, can consciousness, without which time
cannot be conceived, have arisen in time? How can
bodies and psychic phenomena, which always presuppose
consciousness, have given birth to it ?

It will be clear to every one who has properly con-
ceived the world as existing in time and space only as a
content of consciousness that the creative power cannot
arise from the thing created, the subject from the object,
the perceptive power from the thing perceived.

Consciousness cannot be imagined, because it is
itself the imaginative force. Consciousness is the

NATURE, HISTORY, AND ETHICS

405

cognitive force, which creates the objects of its
knowledge in the very act of perceiving them. Its
knowledge is action . 1

It is not our purpose to go into philosophical
questions. We merely wish to point out the limits
of the theory of evolution, and show that there is
something that cannot be subjected to either scientific
or historical investigation.

There is one more point that we must make clear.
We were justified in accepting the view that the
more complex animals have descended from the less
complex. The multicellular have been evolved from
the unicellular, these from unnucleated animals, and
these in turn from inorganic matter. But we must
not forget that even the simplest organisms possess
an infinite diversity, and that each of them has its
individuality, which can never be completely replaced

1 The reader who has never reflected on these questions will do well
to think of himself. What do I know of the world ? What is
absolutely real and certain about it ? It is absolutely certain that
there are sensations in me, but that is all. The world, my fellows, and
all they tell me, are so many sensations in me. It might all be a
dream ! I know for certain only that something is taking place, that I
have sensations. I can imagine that I am dreaming of the world, my
life, and my fellows. This figure should be most helpful to conceive
the matter.

My own body and my whole psychic life are only sensations in
me. This comprehensive sensation, embracing all that occurs, is
consciousness. It is impersonal, and not bound up with any particular
man, for his very individuality is a content of consciousness.

This view does not do away with the reality of the world. The
world holds its reality as a content of consciousness. All its phenomena
remain as we know them, and the relations of its various parts and
phenomena to each other remain, because consciousness dominates
the whole.

406 DARWINISM AND THE PROBLEMS OF LIFE

by another. Even in inorganic matter every particle
is an “ individual.” It has innumerable properties
and diversities, and does not entirely resemble any
other particle. All bodies have been formed from
other bodies, or — more correctly — all bodies are
constantly changing, yet never lose their nature as
bodies. Hence in nature we have only processes of
transformation. If a protozoon seems to be simpler
than a human being, and an element still simpler than
a protozoon, we must never forget that even the
“simplest” bodies are much too complex to be
grasped by us just as they are, without any mental
modification. No theory of evolution, therefore,
enables us to understand the nature of matter ; that

can only be done by a mental process of transformation.
• •••••«

There is a further province of evolution that we
must touch on before we conclude — the evolution of
the human race, the history of civilisation.

The scientific method has been applied here also,
and we give the name of “ sociology ” to this treat-
ment of the history of civilisation. The aim of this
science is to gather the common features of the
various forms of human society, and formulate laws
in virtue of these.

Thus we can study the common elements in the
evolution of different races, and draw up laws which
apply wherever there are nations. In fact, as these
laws must be independent of time, they must be valid
in the past and the future, and they enable us, to some

NATURE, HISTORY, AND ETHICS 407

extent, to forecast the future of the human race and to
lay down certain guiding rules that may be useful in
preparing the future.

Sociology cannot, indeed, ever replace or displace
history. It can never tell us the real course of particular
racial developments. For instance, a sociological law
to the effect that races living on the sea-coast must
utilise the sea, because that is their only chance of
survival, cannot give us any information on the interest-
ing questions, how the first boat was built, who was its
inventor, and what gave him the idea.

Nevertheless, in human history natural laws, which
include the laws of sociology, give us the right to use
certain evidence, so that we can reconstruct, in its
general outlines, a history of humanity that has a high
degree of probability. Let us try to determine the basis
of this history, which is of considerable importance to us.

The first men lived in isolation or in families. Their
special habits — we need not go into them in detail —
were such that those had the advantage who entered
into close relations with their fellows, as they could then
help each other, and take better care of their offspring.
Thus natural selection would favour the more coherent
social groups.

In this way men of a greater social disposition were
always selected. Those who continued to wander singly
through the forests were not so well placed in the
struggle for existence as those in community, and they
gradually but steadily disappeared. Again amongst the
social groups those individuals were constantly weeded

408 DARWINISM AND THE PROBLEMS OF LIFE

out who menaced the communal life. If they were too
numerous the whole community collapsed, either from
internal troubles or in conflict with more coherent
groups. If these individuals were few, they were driven
away or destroyed by their fellows, and were unable to
sustain the struggle in isolation. Thus it is the first
condition of all social life that no member shall endanger
the life of another. Hence all primitive men that had
murderous thoughts against their fellows would be
gradually weeded out.

The more coherent the communities, the more com-
plex the social instincts would become by means of
selection. The property of one’s fellows would come
to be respected as well as their persons, and it was
not long before thieves were put to death. In a
word, all variations with lower social instincts came
to be destroyed, and only the most social variations
preserved.

Thus from the start those individuals were selected
whose instincts were the most useful to the community.
When one of these individuals committed murder, he
acted contrary to his instinct, and an action contrary to
one’s instinct is always, even in the animals, accompanied
by a feeling of pain, as we saw in the second chapter.
This feeling may have been the beginning of conscience.
The closer the co-operation in the community, the more
confidently were those preserved who did not disturb
the communal life — those, in other words, whose feeling
of discomfort was strongest if they ever acted against
the social instinct. In this way an increasing number of

NATURE, HISTORY, AND ETHICS 409

men were selected whose conscience was pricked, not
only if they committed murder, but also if they were
guilty of theft or any other crime against the community.
That they were able to act at all against the instinct was
due to the fact that selection favoured not only the more
social, but also the more intelligent, members. Intelli-
gence — and intelligence alone — can bring a man to act
against instinct; just as in the case of the animals it is
only the most sagacious, such as the dog, that can act
contrary to their instincts. However, this disadvantage
of intelligence is insignificant in comparison with its
many advantages.

Hence in the first human societies “good ” and “ bad ”
were synonymous with socially useful and prejudicial.
Primitive men would not be conscious of such ideas.
The “ good ” acted unconsciously on their instinct ; they
were chosen by selection, and the “ better ” were
favoured amongst their descendants. As the human
intelligence continued to develop, and gave birth to
speech, to think and act in a socially useful way became
a matter of course to them, to such an extent that they
would regard social conduct as the rule in life, as moral
or “good, without being conscious of its utility. They
then endeavoured to foster “ good ” conduct by punish-
ment and education, and here^again they were assisted
by selection, which favoured the “best” races.

The origin of conscience by natural selection is
confirmed when we turn to study the races that are still
at a low level of culture. Amongst these, “ good ” and
bad often mean something quite different from what

410 DARWINISM AND THE PROBLEMS OF LIFE

they do with us, and conscience pricks them in regard to
other actions. It is not necessary to go into details.
One can read in any manual of anthropology that in
many races murder, pillage, and even theft are not
regarded as evil ; that an Indian will feel remorse, for
instance, because he has not killed anyone, but never
because he has done so. Adultery, again, is often so
general that the neglect of it is regarded as a disgrace,
and it is well known how the men offer their wives to
their guests in many races. The cannibal never feels
remorse for having eaten anyone. On the other hand,
many savages feel remorse for an action that is in our
eyes indifferent or even good. In fine, one needs little
acquaintance with ethnography to see that “good” or
“ bad ” have not a common value for all men, and that
all men have not got an inner voice that tells them what
is “good.”

Educated people have a more sensitive conscience
than those of a lower condition, and this again is ex-
plained by natural selection. They usually marry
refined partners ; at all events they rarely choose those
with crude feelings and a disposition to gross conduct
without the check of remorse. Thus, amongst the
educated, the individuals with the gentler instincts are
always selected for reproduction, and therefore
those in whom any violent deed will be followed by
remorse.

We could expand this idea much further, but that
is not our purpose. We wished merely to show that
conscience offers no difficulty to the man who accepts

NATURE, HISTORY, AND ETHICS 4II

natural selection. It can be understood as an instinct,
and instincts arise and grow by natural selection.

But we should be one-sided if we tried to explain the
higher civilisation solely by selection of the more socially
disposed and the more intelligent. There is a second
factor to be considered, even a more important one.
This is tradition.

Tradition is found almost exclusively amongst human
beings. It may be that among the higher animals a
method of catching prey, or building the nest, or
singing, is maintained by tradition, perhaps even
furthered by it, the young learning from the old ; but
this hardly calls for consideration. It is quite otherwise
with man. In his case tradition has a solid foundation
in speech, in drawings and the work of the hand. It is
due to this that the skill which one man has acquired
during life is not lost when he dies, but taught to his
descendants ; they can learn it in a short time, and
advance it in their turn. In this way tradition brings
about a certain mental transmission of acquired
characters, though this has nothing to do with the
Lamarckian principle, since nothing is inherited.

Let us take an instance.

In a certain coast-land a man worked throughout his
whole life at some contrivance for enabling people to
travel on the sea. Towards the close of his life he
invented a boat. If there were no tradition, the
invention would die with him, and the human race
would have to wait until some germ-variation happened
to occur that qualified the man developing from it to

412 DARWINISM AND THE PROBLEMS OF LIFE

build a boat once more. Tradition made it possible,
not only for others to copy the boat, and for their children
to learn the art, so that it became a lasting possession of
the people, but also for improvements to be made, since
the children did not need to reflect all their lives on how
to make a boat, like the first inventor ; they learned
the work in a shorter time, and were thus able to devote
their lives afterwards to improving it, and could transmit
this knowledge to their descendants.

The whole of our higher civilisation would be im-
possible without tradition. Our books inform us of the
achievements of former ages, and inscriptions and draw-
ings acquaint us with long extinct races. The objects
of civilisation are our property, and we build further
upon them. We have implements from the very dawn
of humanity the essential parts of which still represent
the foundation of all creative work. Language, like a
great river, brings on its waves the achievements of
earlier generations down to our own time ; it unites all
generations in an unbroken chain. All this is so
obvious that we need say no more of the subject.

What has been attained through tradition may be
modified and improved by natural selection. Let us
return to our illustration of the boat. It is quite clear
that the race whose boats have been improved owing to
tradition beyond those of a neighbouring, hostile race,
will be able to defeat the latter in a sea-fight, and so
spread into its territory. With the people will go the
traditional possession, the better boat. Thus in a sense
this has conquered the inferior outcome of tradition.

NATURE, HISTORY, AND ETHICS 413

To give another instance, let us suppose that a race
has acquired by tradition such admirable political and
juridical forms that its co-operation is lifted to a higher
level. If a neighbouring race lives under worse political
and juridical conditions, it is probable that the first race
will conquer when war breaks out, because its more
coherent nature leads to more energetic and harmonious
operations on the part of its army. If the law of the
conquerors is forced upon the losers, this survives, while
the inferior law disappears.

The struggle of traditionary benefits may, of course,
be peaceful ; the best acquirement may conquer without
strife or blood-shed. Suppose, for instance, that the
excellent position of a state leads to the prolific multiplica-
tion of its citizens ; this constantly increasing community
will gradually oust its neighbours in the most peaceful
way. With it survives its political system.

Thus it is possible to trace the probable course of the
evolution of civilisation and ground it on scientific laws.
Opinions will differ as to the value of the attempt. On
the one hand it will not be entirely convincing because
it is no more than probable ; on the other hand it will
be very difficult to provide it with a purely scientific
foundation. Words like “improve,” “valuable” and
“ progress ” will be only too apt to creep into it, and
these meanings will involuntarily be imputed to the laws
of evolution. We are accustomed enough to regard
nature in the light of what is “ valuable ” and “ valueless,”
and will be much more apt to use these terms in dealing
with civilisation. It is a question if we can ever speak

414 DARWINISM AND THE PROBLEMS OF LIFE

of changes of civilisation — which is the only way to put
it scientifically — without considering them in relation
to some standard of value that is regarded as generally
valid.

However, we may grant the possibility of a history of
civilisation on scientific lines, but we must entirely reject
the notion of a scientific ethics. It has been said that
the laws of science must apply always, even in the future,
as they are independent of time. Hence we should be
able to determine the laws of evolution in virtue of
which the human race has not only changed, but will
continue to change. We know that the fittest survive
in the struggle for existence. The point is, therefore,
to establish what is the fittest in particular cases. When
that has been done, men will be disposed to aim at that
particular adaptation in order that they may survive.
We must, of course, also determine the general direction
of human development, and must know what will be
the best adaptation in ages to come. If we can obtain
definite knowledge on these points, laws must be framed,
States constructed, and the social order regulated, in
relation to them. That is the language of the sociologist.

Above all things, nothing must be done in opposition
to natural selection, because it is this that always confers
their greatest advantages on living things. It is a false
humanity to spare those with hereditary disease, as in
this way the disease is spread. It is not necessary to
put them to death, but merely to prevent them from
marrying, so that the disease-germs may die with them.
If, for instance, some years ago, all consumptives had

NATURE, HISTORY, AND ETHICS 4 1 5

been prevented from having children, there would soon
be no people with unsound lungs. We look too much
to the individual. We ought to care for the soundness
of the species, as nature does, and then the individuals
also would be sounder.

Other institutions show us an inverted selection.
War brings about a “ survival of the weakest,” as it
is precisely the strongest elements that perish in them,
while the weaklings can continue to bring forth their
puny children in peace at home. It is, therefore,
unspeakably perverse and ridiculous to say that a little
blood-letting from time to time does a nation good, and
keeps down over-population. Apart from the fact that
with the vast sums spent on the army waste lands might
be cultivated, and numbers of families provided with
new and secure dwellings, this blood-letting deprives
the nation of its soundest blood, and every battle
lessens the vital force of the next generation.

Our whole military system should be abandoned.
From the fact that the strongest enter military service,
they generally lose the time for founding a family, while
the less strong civilians have young earlier. Thus the
weaker children come earlier and are more numerous,
and this gradually enfeebles the race.

Finally, we have a case of inverted selection in the
Catholic principle of clerical celibacy. In Catholic
countries the stupid survive, as a glance at such lands
is said to show. As a general rule in a Catholic
country, those are chosen for the clergy who are above
the average of intelligence that suffices for peasants

41 6 DARWINISM AND THE PROBLEMS OF LIFE

and artisans. But these more intelligent men are
prevented from reproducing. In this way for centuries
the more intelligent have been taken out of each
generation, and their better germ - qualities have
perished with them, because they were forbidden to
have children. Thus the intelligent were continuously
selected for destruction, the stupid were enabled to
pass on their inferior germ-qualities to the next genera-
tion, and the mental level of the race was bound to be
gradually lowered . 1

However, the scientific treatment of the evils of our
time seems to be fairly justified. What must we make
of the positive moral laws of sociology ?

We must point out in the first place that there is a
view which predicts the greatest future, not for society,
but for the individual. This is the well-known philo-
sophy of Friedrich Nietzsche, though founded before
him by Max Stirner.

1 We may regard celibacy from another, I would almost say a more
fitting point of view. We are told that the peasants give to the clergy
those of their sons who are least suitable for agricultural work. In
other words, the weaker are selected for barrenness, and so celibacy
must tend to strengthen the next generation. In the same way it may
be contended that military training is of great service to our young
men. It would certainly be better for humanity if nations did not
face each other armed to the teeth, but we are still very far from this,
and standing armies are at present inevitable. Moreover, it may be
objected to the proposal to condemn weaklings and the diseased to
infertility that it is impracticable. In my opinion all these questions
should be settled by the historical method, because the work of natural
science is merely the theoretical interpretation of the world. This will
be made clear in what follows.

I was, therefore, surprised when a reviewer in a New York Journal
observed that my point of view — which he calls Darwinian-ethical —
can hardly be maintained on practical grounds. That is not my point
of view, as I think I have clearly stated.

NATURE, HISTORY, AND ETHICS 417

We see from this that Darwinism may not only lead
to the prosperity, but also to the decadence, of a society,
as Nietzsche’s “egoism” is built up rigorously on a
basis of selection. In fact he attributes a more
energetic action to selection than the social Darwinists
do. Nietzsche especially rejects the precept of love of
one’s neighbour as “a morality of slaves.” It is hatred
alone that makes the fittest to survive. “ The strong
drift just as necessarily away from each other as the
weak do towards each other.” Strong and masterful
men must arise who feel themselves bound by no
restrictions and follow unsparingly the primitive instinct
of man towards violence, with no regard for science or
morality. Science bids fair to-day to rob man of all his
self-esteem. Astronomy dwarfs him by reducing him
to insignificance in the great universe. Away with
science, then, since it hinders the development of man
and the beyond-man ! “Nothing is true; all is
permitted.”

The State is an evil. Men cannot give the rein to
their violence in it, until they at last turn it against
themselves and mutilate themselves. This was the
origin of conscience, another evil, according to
Nietzsche. The primitive human instinct to fierce-
ness cannot express itself externally and is reflected
inwards.

But a time is coming when men will live as masters

once more. When one great State embraces the whole

world and no enemies threaten it, the older selection

will no longer be a condition of existence. Then

2 n

41 8 DARWINISM AND THE PROBLEMS OF LIFE

morality will have survived ; men will dare to express
their individuality, and their long repressed egoisms
will explode. There will be a fierce struggle for the
light of the sun. No values will be recognised. The
day of the beyond-man will have come.

We will not go further into the subject, as this is not
the place to deal with the ideas of Nietzsche. We
merely wanted to point out that they are based on
selection. As a matter of fact, little can be said against
them from the scientific point of view. The Darwinist
believes that the struggle for life creates the best — let
the phrase pass for the moment — and is most effective
when it is most destructive. Away, then, with what-
ever limits the struggle ! Away with the State and the
whole of civilisation ! Away with our physicians and
hospitals, which run counter to selection, by preserving
the weak ! Epidemic diseases are the most drastic
selective agencies ; they suffer only the very soundest
to survive, and the generation that follows their ravages
is the healthiest conceivable.

How will it be when one state embraces the whole
world ? Then all selection will cease, and everything
will be done in accordance with laws framed by men
for the attainment of certain ends. But the laws of
Nature that they interrupt can achieve more than man.
Hence we ought to prevent the formation of such a
state and all institutions that restrict the struggle for

life.

Can Nature’s eternal laws be corrected or suppressed
by the puny hand of man ? A natural law is some-

NATURE, HISTORY, AND ETHICS 419

thing that holds good everywhere and at all times, and
cannot be suddenly destroyed by the very objects to
which it applies.

It is true that the laws of nature hold good always,
and cannot be influenced by civilisation. Selection
would act even in a state that covered the whole world.
It merely demands that those shall survive who are
most in harmony with their actual environment. In a
universal state the conditions would be different from
what they are to-day. Selection would then allow those
individuals to multiply most who are best and quickest
able to secure maintenance and found a family. Even
if the state extends equal care to all its members there
will always be variations in the fertility of the citizens,
and the more fruitful will tend to predominate.
Whether they will be the more intelligent is another
question. It is, in fact, pretty clear that in such a
universal state, where cleverness would be no advantage
and would not put a man in a better position to found a
family, and where selection would no longer favour men
according to their degree of intelligence, ability would
diminish. In the end the citizens might become too
stupid to maintain the state. It would break up, and
then selection would once more favour the more
intelligent ; they in turn would build up a state, which
would meet the same fate, and so on in an endless cycle.

However that may be, we can see clearly how
difficult it is to build up a science of morality, or ethics,
on the principal of selection. We can hardly determine
what is “ better ” for our own time ; how much less

420 DARWINISM AND THE PROBLEMS OF LIFE

can we do it for the future. How can we say with any
confidence what the conditions of life will be in the
future with which the coming race will have to
harmonise.

The Darwinists who would deduce a system of ethics
from their theory say that moral laws are only safely
established when they are natural laws. We have seen
how a law of nature is formulated. Individual
phenomena are considered in their common features,
and these are then embodied in a law. Moral laws
must be framed in the same way. The individuals have
then to range themselves under the law, like an example
of a genius under the generic title. Hence a scientific
ethics would have to demand that everyone should be
as far as possible an “average man.” Only what he
has in common with his fellows is essential ; his
individual and distinctive traits must be as slight as
possible, if he is to be as moral as possible — in the
scientific sense. Science, which overlooks individuality
in the formation of its concepts and regards it as
unessential, must demand that the men who would
realise its ideal shall have little or no individuality.

As a matter of fact, we find confirmation of this when
we read about future states and Darwinian ideals. No
account can be taken of the individual ; he must merge
into the general. The “general” or common interest
is the basket of the “ social ” state.

Nietzsche has given us a masterly description of the
Darwinian ideal of the coming race in his “ last men.”
It shows the complete insipidity of the theory that looks

NATURE, HISTORY, AND ETHICS 42 1

only to the common interest and suppresses the
individual . 1

“ The earth will then have become unimportant, and
the ultimate man, who makes everything important, will
hop about on it. His species is ineradicable, like that
of the flea ; the ultimate man lives longest.

“‘We have devised happiness’ — say the ultimate
men, and wink knowingly.

“ They have left the regions where it was hard to
live ; for warmth is required. They still love their
neighbour, and rub against him ; for warmth is required.

“It is regarded by them as sinful to turn sick or be
mistrustful ; they walk warily. It is only the fool who
still stumbles over stones and men !

“ A little poison now and then — that makes pleasant
dreams. And much poison at last, for a pleasant death.

“ They still labour, for labour is an entertainment.
But they take care that the entertainment does not
hurt them.

“ They no longer become poor or rich ; both are
too troublesome. Who of them still wants to rule?
Who of them still wants to obey ? Both are too
troublesome.

“No herdsman, but one herd ! All want the same.
All are equal. He who thinks otherwise goes
voluntarily into the madhouse.

“‘Formerly all the world was insane’ — say the
most subtle of them, and wink knowingly.

“ They are wise, and know all that has happened ;
l “ Thus spoke Zarathustra ” (Commons’ translation).

42 2 DARWINISM AND THE PROBLEMS OF LIFE

so there is no end of their derision. They still fall
out, but are soon reconciled — otherwise it would spoil
their stomachs.

“They have their little pleasures for the day, and
their little pleasures for the night ; but they have a
regard for health.”

This is the pass that things will come to if the
Darwinian - ethical ideals are realised. A “ deadly
generalness ” will dominate the world. Happiness and
unhappiness are antitheses, and there should be no
antitheses in the scientific world of ideals. Nothing
low — but nothing high : no hatred — but no love : no
depth — but no altitude : an eternally monotonous life,
without struggle and without victory.

We see, then, that the ideal of a scientific guidance
of men means, to everyone who esteems individuality,
an intolerable mediocrity. But that is not the only
objection to a scientific ethics. It can be shown that
it has no right to exist at all.

Every system of ethics must prescribe something
to a man ; it must tell him his duty. That is evident.
If moral laws are to be laws of nature, they must,
like the latter, have a universal validity. They then
show what exists, and must exist, everywhere ; it is
the very essence of natural laws that they act
necessarily. But if moral laws, being natural laws,
must be realised of themselves always and every-
where, there is absolutely no purpose in directing a
man to act according to them. If a thing is so, it is
superfluous to make it a duty for a man to bring it about.

NATURE, HISTORY, AND ETHICS 423

In reality the world has no place for duty from
the scientific point of view. The cosmic process
goes on inexorably. There are no ends towards
which the eternal changes are working ; and there
is no force that can arrest or control the rolling
wheels.

The stars travel on in the infinite universe. They
exist at one moment of the world’s history, and are
gone the next. On a small body in a corner of the
universe certain beings were produced in one of
these moments, to grow rigid for ever with their
planet in the next. Such is the story of mankind.

How ridiculous and aimless it must be, in view of
this conception of things, to direct a man how he
shall act. As if he could make the slightest change
in the inexorable march of cause and effect ! How is
it possible to set before a man aims that he shall
strive to realise, when there is no “teleological”
occurrence in the world, when even human actions
are determined by causes that lie behind , not before
them ? 1 The utmost that science can say is that an
ethic, a setting-up of ends to be attained, has no
meaning. It can only direct a man to let himself be
borne in peace on the stream of cause and effect,
without doing anything, because his action could have
no aim and no result. The only possible scientific
ethic is resignation.

Is it true that the laws of Nature are the sole

1 There can, of course, be no question of free will to the
scientifically-minded man.

424 DARWINISM AND THE PROBLEMS OF LIFE

moral laws because they alone lead to ever-increasing
values? We have already rejected this idea so often
that we need not enlarge on it here. The principle
of selection is not a principle of progress. It does not
lead up inevitably to the “highest being,” to man; he
is the accidental outcome of one branch of the organic
system. Even in the evolutionary series, of which
man is the terminus, we cannot speak of progress ;
it would not be scientific, but anthropomorphic. In
the eyes of science man is not “higher” than the
other animals. It is precisely one of the elements
of the success of the scientific view that it brings
man into level with other living things. It is illogical
suddenly to raise him again to the position of the
“highest being.”

Further, it is entirely wrong to say that selection
gives increasing value to the frames of animals, because
it makes them increasingly fit to maintain their exist-
ence. Maintenance of existence has nothing to do
with maintenance of value. Science has only attained
its great results by studying the world independently
of all considerations of value. It sees nothing but
changes. Certainly, its organisation will seem valuable
to an animal when it sees that it fares better in life
than its fellows owing to it. In the same way, man
will attribute value to everything that is useful to
himself. But this way of thinking is not scientific.
The scientist has only to determine that there are
human beings and animals, and that some survive
and others perish on account of their bodily character-

NATURE, HISTORY, AND ETHICS 425

istics. He cannot wish that certain animals, or even
man, may maintain their existence as long as possible.
Worth is only conceivable as the opposite to worth-
lessness. Dualistic ideas of that kind should have no
place in a monistic system . 1

We have now reached the fundamental objection to
all scientific ethics. Science regards cosmic processes
merely as changes, and pays no attention to values.
It abandons its methods entirely and contradicts itself
when it begins to recognise values. Hence it cannot
have an ethics, because this has no meaning unless
the moral laws that it sets up, and especially the life
of man and the improvement of it, are regarded as
having worth.

Thus for science — to repeat our conclusion — there is
no such thing as an aim, an end, or a value in the
world. There are only changes in accordance with
eternal laws. The laws are beyond the control of
any human being. The whole history of humanity
consists of certain changes that take place on a speck
of dust, and occupy only a second of the world’s time.
All man’s actions, all his struggles and efforts, are so
many phenomena that follow necessarily upon other
phenomena ; they are as void of worth as the fall of
the meteor, or the roll of pebbles on the beach.

The whole cosmic process is aimless. There is no
such thing as a sense of life.

••••••«

1 For the same reason, the phrase “ worthy of selection ” is unfor-
tunate. It does not give one a very scientific impression when we
find sociological writers speaking incessantly of values.

426 DARWINISM AND THE PROBLEMS OF LIFE

Yes, in a scientific conception of the world there is
no sense of life. But that does not mean that there is
no such thing anywhere as a sense of life. If science
affirms that, it is passing beyond its sphere.

We have seen that the scientific conception of the
world does not present reality itself, but an inter-
pretation of it. We have also seen that there is a
second way of conceiving it — the historical. History
looks first and foremost to individuals, and shows that
in reality no individual can be substituted for another.
History has a perfect right to read an ethic from
reality — an ethic that lays on each personality the
task that he alone and no other can perform. But
it is not our place to enlarge on this.

If science tells us to reject the historical conception
of life it is illogical. When it censures the historical
method, it assumes it to be of less value than its own,
and thus once more oversteps its province.

Briefly, we see on all sides that science lands itself
in contradictions the moment it goes beyond its sphere.
Its task is merely to give us a knowledge of the world.
In doing this consistently it has attained marvellous
results, and has formed a “ monistic ” or unified view of
the world. The foundation of the monistic structure
and all the columns and buttresses that support it
imply a disregard of all values. Hence monism cannot
frame an ethic unless it abandons all its supports, which
are inconsistent with values. In that case, monism
breaks down.

When, therefore, we find practical counsels, aims,

NATURE, HISTORY, AND ETHICS 427

and values in monistic works, we have no longer
monism before us, but dualism — dualism, in fact, of
the most positive character. We cannot recognise
two systems as equally valid ; we must leave only one
standing. But we destroy it when we turn to the
second, even though we demand that it shall be based
on the first.

There is one further point.

Not only has empirical science, which recognises
no values, no right to deny worth and the sense of
life generally, but it is itself subordinate to the sciences
that endeavour to determine values. Before it begins
its work some standard of value has to determine
whether its procedure is to have any meaning. This
standard is the value of truth. Knowledge of the
world must be of value to a man before he applies
himself to the empirical sciences that help him to
attain it. And the methods of acquiring this know-
ledge, which disregard all values, must have a value
for him.

Thus all science presupposes a will to attain the
truth, a will to reach the goal of knowledge. Over
the portals of every science are inscribed the words :

Thou Shalt.

We have now reached the end.

These last considerations have shown us that we
are justified in believing in a sense of life, and that
there must be duties, since the idea of duty precedes
all knowledge.

428 DARWINISM AND THE PROBLEMS OF LIFE

But science has nothing to do with these problems.
It is of its very nature to pass no judgment on the
value of other methods of investigation.

It presses on to its goal, the comprehension of the
world, regardless of all else. It gives an impulse
to the human mind that bears it on to ever greater
heights. The vision steadily enlarges. The individual
disappears ; the world lies at the feet of the spectator
in its broadest outlines.

But we press onward. It bears us beyond the world
to a height whence we can survey the entire universe.
He who would see over the whole world must pass
beyond it.

There, in pure ether, the mind is able at last to
grasp the infinite all.

INDEX

A chtheres percarum, 247
Adaptation, law of, 118
Aim not known in science, 425
Air-sacs in birds, 100
Algae, 236
Albumen, 237
Albuminoids, 231
Alpine hare, adaptation of, 54
American notions, 47
Amoebae, 292, 294
Amphimixis, uses of, 256-61
Analysis, chemical, 231

,, the task of science, 396
Angiosperms, 236
Annelides, 264

Antennae of the Crustacea, 245
Antlers, 84, 89

„ of the giant stag, 207-13
Ants, 285-6

Archaeopteryx, 39, 121, 157
Arctic hare, evolution of the, 32, 54
Argus butterfly, the, 195
Aristolochia, 200
Art, analysis of, 71
„ animal destitute of, 71
Articulates, 184
Artificial selection, 29, 166
Asexual germ-cells, 302
Atoms, 365

Attention in animals, 76
Aulostomum gulo, 268

Bacillus, adaptation of the, 373
Bacteria, nitrogenous, 318
Balloons, birds dropped from, 102
Barbel, the, 176
Basic particles in the germ, 319
Bee hawk-moth, the, 194
,, queens and workers, 213
,, state, origin of the, 214
Bees and plants, 200
Beetles, wings of, 203
Beyond-man, the, 417
Bilharzia hcematobia, 282
Biocoenosis, 23, 42
Biogenetic law, the, 17 1, 247
Biogens, 232-4, 31 1

,, evolution of the, 317

Bird, anatomy of the, 100
,, evolution of the, 38, 136
,, life of the, 52
,, song of the, 78, 94-6
,, soul of the, 79
Bittern, the, 96
Black-arches, the, 43, 160
Blackbird, the, 48
Black-cock, the, 85, 87
Blue-throat, the, 107
Bombycidae, the, 159
Botkriocephalus latus, 282
Brain and mind, 384

,, development of the, 249
Branchiopods, 254
Brontosaurus, the, 120
Bullfinch, the, 81-2
Bull-head, the, 173, 174
Buttel-Reepen on the bees, 214
Butterflies, 187, 189-93

Cabbage-butterfly, the, 195
Callima, 194
Caprifoliaceas, 200
Caracoideum, the, 158
Carp, eggs of the, 26
Cast of the skin in insects, 187
Cat and the mouse, 67, 68
,, why its fur stands out, 88
Caterpillars, 188
Catholic clergy, 415
Causation, infinity of, 361
Cause and effect, 349
Celibacy, evils of, 415
Cell, the, 289
„ cleavage of the, 294
Cellular animals, 319
Cellulose, 237
Cetiosaurus, the, 120
Chaffinch, the, 48
Chance, 353

Change of function in organs, 244
„ of hosts in parasites, 275
Chlorophyll, 235, 317
Choice, female, 80-7, 95
Chromatin, 289
Classification of animals, 1 17
Co-adaptations, 207

430

INDEX

Coat of insects, development of the,
205-7

Cock, spurs of the, 84
Cockchafer, the, 84
Cold, effect of, on butterflies, 341
Cold-blooded animals, 1 19
Colour as protection, 53-5
Colours, animal, origin of, 91

„ of animals and selection, 166
„ of insects, 185
Combinations, chemical, 230
Common features expressed in ideas,
393

Concepts, 378

„ of animals, 392
Conscience, evolution of, 408
„ variations of, 410
Consciousness, 386

„ not evolved, 404

„ unimaginable, 404

Coecum, the, 159
Co-operation in the body, 165
Copepoda, 252
Copper butterfly, the, 195
Coquetting, 86
Correlation, law of, 164
Cosmic process, the, 425
Cosmozoic theory, 314
Courtship of animals, 82-8
Coyness, 86
Crab, legs of the, 245
„ pincers of the, 204-5
Craw-fish, the, 240, 245
Creation, theory of, 155
Cretaceous period, 119
Cricket, pairing of the, 196
Cries of birds, 94
Crocodile, age of the, 149
Cross-bill, the, 98
Crustacea, 184

Cuckoo, as destroyer of insects, 45
„ cry of the, 95
Curiosity in animals, 76
Cyanic theory, the, 316
Ciliated infusoria, 293
Circulation of blood in the bird, 156
,» » frog, 155

Civilisation, effect of, on animals,
42 , 47

Civilisation, evolution of, 406

Dachshund, the, 210
Daphnidae, 252

Darwin and over-production, 26
Darwinian ethic, the, 417, 420
Darwinism, definition of, 38
Death, nature of, 307-11
„ utility of, 312

Definite variations in animals, 258,
332

Degeneration of organs, 156-8
Descartes on instinct, 64
Descent, theory of, 37
Descriptive science, 399
Design on butterflies’ wings, 191
Determinants, 333
De Vries, Hugo, 344
Differentiation of life-forms, 318
Dinosauri, the, 120, 129
Direction, sense of, in birds, 1 10-12
Distomum hepaticum , 274, 283
Distomum macrostomum , 283
Divisibility of bodies, 362
Division of labour in organisms, 290
Dochmius duodenalis , 278
Dragon-fly, the, 19, 22, 194, 196
Dreams and art, 72
Dualism, 427
Duty, idea of, 422, 427

Ear-bones, the, 154
Earth, end of the, 312, 3 23
Earth’s history, periods of the, 122
Earthworm, the, 238

„ use of the, 266

„ regeneration in the, 267

„ summer store of the, 56

Earwig, the, 202
Echinoderms, 263
Echinorhyticus , 272
Economy of nourishment, 168-70
Eel, reproduction of the, 178-80
Eel-pout, the, 172
Efficient causes, 367
Eggs, colours of, 92
„ number in certain animals, 26
„ of reptiles, 138
„ poisonous, 176
„ provision for development of, 59
Egoism, 417
Egyptian plants, 34
Egyptian seeds do not grow, 233
Elastic types, 132
Elements, chemical, 229
Elephant, trunk of the, 241, 332
Embryo, development of the human,

Embryonic adaptations, 249-51

„ development, evolution-
ary aspect of, 170, 248-51
Empirical science, 396
End in organisms, 364
Eri s/alis, 193
Eternity of matter, 314
Ether, 381

,, invisibility of, 382

INDEX

43 [

Ether-particles, metaphysical, 395
Ethics, 419

Evolution, the theory of, 37
„ a slow process, 360

„ based on probabilities, 401

„ nature of evidence for, 400

„ not a purposive process,

373

Evolution of life-forms, 318
External influence on organisms, 340
Extinction of species, causes of,
125-31

Fakir, sham death of the, 233
Falcon, the, 98
Feathers, origin of, 136
Feeling in the mammal and the bird,
53

Female choice, 81-7
Fertilisation of plants, 197-9
Fertility of animals, 26, 58
Fibula, the, 168

Field-cricket, apparatus of the, 209
Field-mouse, the, 43
Final causes, 364
Fingers of the bird, 157
Fins, evolution of the, 154
Fishes, eggs of the, 59
Fitchet-weasel, the, 57
Flagellates, 292
Flea, the, 202, 270
Flesh-eating, beginning of, 238
Flight, instinct of, 66, 215
Flowers and insects, relation of, 197
Fluke, the, 282
Flying fish, the, 137
„ squirrel, the, 137
Flying muscles of birds, 100
Food instincts, 66-8
Forestry and birds, 47
Formative energy in organisms, 344
Forms of living things, 352
Fossils, absence of early, 122-3
,, formation of, 123

,, scarcity of, 123-4

Fox, the, 23, 28
Free will, 423

Freedom, sense of, in play and art, 73
Frog, the, 21

„ adaptations in the, 145
Frog-spawn, 145
Fundulus heteroclitus , 1 77
Fungi, 235, 238

Future society, the Nietzschean
forecast, 419

Gall-fly, the 254
Galleries of ancestors, 402

Game, injuries done by, 43
Games, nature of, 60-377
Gatke, H., 79

„ on speed of migration, 98,

101

Genealogical trees, 359
General concepts, 379
„ terms, use of, 392
Generic names, 393
Geology, evidence of, 35
Geological succession of animals,
35-6

Geometer-moth caterpillars, 193
Germ-cells, 255, 297

,, not teleological, 366

,, selection in the, 333

Germ-plasm theory, the, 296
Germinal selection, 333-40

,, _ ,, teleological, 371

Gill-clefts in the human embryo, 171
Gills, evolution of the, 156
„ of snails, 244
Good and bad, meaning of, 375
Gordius aquaticus , 268
Gourd-worm, the, 274, 283
Graeser, Kurt, on migration, 105
Grant Allen on heredity, 306
Grasshopper, the, 137, 185, 187
Groos, Professor, on animal play, 60
Growth of insects, 186
Glyptodont, the, 126-8

Haeckel, Professor, 399
Haemopis vorax, 268
Hairy coat, disappearance of, 342
Hamster, winter sleep of the, 56
Hare, the, 23, 28, 31
Harmful animals, 43
Harmonious adaptations, 207
Hawk-moth caterpillar, the, 188
Hawks, 43

Hearing in the fish, 176-7
Heart, the, 155
Heliconides, the, 194
Heligoland, migratory birds of, 98,

102

Henry II., falcon of, 98
Hereditary disease not to be spared,
414

Heredity, 41, 256
„ law of, 1 18
„ nature of, 298
Hermaphrodism, 275

„ in the plant, 199

Hermit-crab, the, 225
Heron, the, 212
Hibernating animals, 55-7
Highest being, man as the, 424

INDEX

432

Histological selection, 333
Historian, work of the, 399
Historical science, 397
History of civilisation, 414
Honey in plants, 199
Horse, evolution of the, 39
„ toes of the, 157
Horse-leech, the, 268
Humanity, true and false, 414
Hydra, 285

Ichneumon-flies, 44
Ichthyosauria, the, 120
Iguanodon, the, 120
Imago, 185, 187
Imagination, 71
Imbauba , 286

Imitation, instinct of, 64, 75
Immortality of the germ-cells, 306
„ ,, protozoa, 307-10

Incomprehensibility of the world,

.377

Indifferent marks of organisms,
163

Individuality, 406
Individual the only reality, 395
Infection of germs, 223
Infertility of mixed crossing, 328
Infinity, 362
Infusoria, 293

„ will survive man, 374
Inheritance of acquired characters,
204, 222-4

Inheritance of impressions, 340
Inherited habits, 214
Inorganic matter has psychic pheno-
mena, 404

Insects, adaptations of, 185
„ growth of, 186
,, origin of wings of, 137
Insectivorous birds, 43-5
Instinct and intelligence compared,

66-7

Instinct, nature of, 64-6
Instincts, origin of, 214
Instrumental music of birds, 96
Intelligence, animal, 55

„ and instinct, 66-7

„ of insects, 216

Intermaxillary bones, the, 154
Intestinal worms, eggs of the, 26
Isolation as an evolutionary factor,
261, 325-31

Jay, song of the, 96
Japan, no singing birds in, 78
Judgments, 378
Jurassic period, 119

Kant, 389

Kingfisher, the, 45, 46

Lamarck, theory of, 40
Lamarckian principle, the, 167, 191
203-227

Lamarckian principle, the teleologi-
cal, 371

Language, scientific value of, 377
Lappet-moth, the, 193
Lame, 185, 187
Last men, the, 420
Laws of science, 397, 401
Leaf-cutter ants, 286
Leech, the, 268
Legs, development of, 168
Leptoccphalus breviroslris , 179
Lepus Huxleyi, 34
Leuckart, R., on parasites, 269
Libcllula depressa, 195
Lichen, the, 286
Life, duration of, 312
„ origin of, 313-6
„ historical conception of, 426
,, nature of, 232
„ phenomena of, 233
Limbs, evolution of the, 157
Linnean principle, the, 34
Lion, mane of the, 88
Living substance, 232
Lizard, intelligence of the, 13S
„ tail of the, 141
Love-dance, the, 85, 87
Love-play, 76
Lumbriculus, 267
Lungs, origin of the, 152
„ of snails, 240, 244

Mach/ERodus, the, 126-8
Magnetic sense in the bird, 108
Males, fights of the, 84
Mammal and the bird compared, 52
Man and the animal not specifically
different, 77
Mantis, the, 196, 216
Marmot, the, 107
Marten, the, 29
Masticators, evolution of, 202

„ of the Crustacea, 246
Mastodonsauri, the, 12 r
Material world, a process of con-
sciousness, 387
Materialism, 385
Maturing of the germ-cells, 322
Maw- worm, the, 265, 272
„ eggs of the, 26
May-flies, 19, 22
Meadow-sage, the, 20 r

INDEX

433

Measle-worms, 280
Mechanism. 350, 369
Mediterranean, former bridge over
the, no

Medium influences, 342
Megalosauri, the, 120
Memory of birds, 1 1 x
„ of fishes, 176
Memory prodigies, 112
Metabolism, 233
Middendorf, 108
Migration of birds, 98-115

„ „ „ altitude of, 99-103

„ „ „ cause of, 103-5

„ „ „ speed of, 98-9

Migrations of animals, 328
Migration routes, 109-10
Migratory instinct, the, 103-15

„ „ origin of the,

103-7

Military system, evils of the, 415
Mimicry, 193-4, 216
Mind and matter, 387-8
,, in the animal, 77
Mixtures, chemical, 230
Mole-cricket, the, 185, 203
Monism, 389, 425, 426
Monstrosities, 348
Moral laws, 422

„ sense, evolution of the, 408
Morality, science of, 419
Mortality greater in males than
females, 81
Mosaic narrative, 38
Moth, the, 187, 190
Moustache, the military, 90
Mucus of the snail, 239, 242
Mud-fish, the, 151, 177
Mussels, parthenogenetic, 254
Mutation theory, the, 344
Mutilations, not inherited, 222
Mutilation of animals, 140-5
Myoxus git's, 56

Natural laws, 380

„ selection, 28-9, 40

„ and sexual selection, 79-82

„ selection, description of, 41

„ selection, is it omnipotent ?,

132

„ selection, mechanical, 368

Nauplius-larva, the, 246, 251
Neanderthal skull, the, 125
Nematodes, 271, 277
Neo-Vitalism, 352
Nerve-tracks, 65
Nerves, motor and sensory, 64
Nesting-places of birds, 48

Newt, regeneration in the, 142
Nietzsche, F., 416

Nightingale, disappearance of the,
47

Novelty, stimulus of, 82
Nucleus, importance of the, 295
Nut-hatch, the, 52

Ontogeny, 247
Optics, 398

Organisation, degrees of, 374
Orgyia, the, 226
Origin of life, 313-18
„ of species, 398
Orthogenesis, 340

,, teleological, 371

Ova, number and development of,
26, 359

Over-production, 25
Ovum, the, 255, 303

„ structure of the, 223
Owl, the, 43
Oxyuris, the, 277

Painter’s gaper, the, 175
Pairing-cries, 95
Pairing of insects, 196

,, season, date of the, 57
Pandorina, the, 297
Panmixis, 161

Parasites, alimentary organs of, 272
,, respiratory organs of, 272
„ sexual organs of, 273
Parasitism, 246, 269-84
Parthenogenesis, 253-7
Passive selection, 357
Peacock’s-eye butterfly, the, 189, 220
Peacock, tail of the, 87, 93
Pentastomum tanioides , 270
Perch, the, 172
Perch-pike, the, 172
Periftaius^ 264
Persistent types, 132
Pfliiger on the origin of life, 316
Phylloxera, the, 43, 254
Phylogeny, 247

Physical changes of the earth, 327
„ conditions of life, 22, 49
„ science, 396
Pigeons, species of, 29-30
Pike, the, 172
Pineal body, the, 158
Pine lappet-moth, 43
Plagues of animals, 46
Plant-eating animals, 237
Plant, evolution of the, 197-9
,, importance of the, 235
Plastic types, 132

2 E

434 INDEX

Plate on heredity, 225
Platodes, 263, 279
Play, analysis of, 60-77
„ animal, 60-77
Plural variations, 259
Plesiosaurus, the, 120
Plectognathic fishes, 177
Poisoning of germs, 223
Poisonous butterflies, 148

„ organisms, colours of, 147
„ . snakes, 139, 143

Polar animals, colour of, 54-5
Political systems, development of,
413

Pollen, 197
Polyp, the, 284, 291
Pond, inhabitants of the, 21
Pond-mussel, the, 175
Pond-snail, the, 239
Porto Santo rabbit, the, 34
Potential immortality, 307
Presentiment of the bird, 107
Preyer on the nature of life, 315
Proboscis of butterfly, 201-2
Processional butterfly, 43
Proper names, 393
Protective colours of insects, 189
Protoplasm, 289
Protozoa, the, 170, 263, 292
Psychic phenomena, 384

„ „ in inorganic

matter, 404

Psychic phenomena in the protists,

403

Psychology, 384
Pterodactyl, the, 121
Pterosauri, the, 120, 130
Pupa, the, 188, 206
Purpose in organisms, 354
„ in science, 373

Racial colours, cause of, 165
Reality, nature of, 395

„ not given in natural science,

383

Recreation not the essence of play,
61

Red breast in birds, 81, 82
Redstart, the, 45
Reduction cleavage, 321
Reflex action, 64, 214
Regeneration of organs, 142
Regions of nature, 20
Regulation of rivers, 177
Reproduction, essence of, 294
„ rate of, 58
Reptiles, age of, 135
Rhine salmon, 48

Rhodeus, the, 175
Richard’s pipit, the, 109
Rigid types, 132
Ringed adder, the, 139, 148
Rivers, artificial control of, 48
Rock-pigeon, the, 30
Rudimentary organs, 158-70

„ parts in germs, 295
Ruffe, the, 178
Rut of animals, 57

Sacculina, 246
Salamander, the, 37

„ and fire, 146
Salmon, spawning of the, 180-1
Satyridm, the, 188
Scar in the egg, 304
Scars, use of, 144
Scented butterflies, 195
Schiller on play, 62
Science, objectivity of, 391
Scientific explanation, nature of, 361
Scolices, 280-1
Sea-anemones, 285
Seed of plants, 198
Selective value, 329
Self-correction of determinants, 336
Self-deception in play and art, 71-2
Self-preservation, instinct of, 356
Sensations as psychic elements, 384
Sense-impressions, 65
Sense of life, 426-7
Senses, action of the, 391
Serpent, habits of the, 138

„ movements of the, 140
Sexual characters, 82-5

„ generation, nature of, 299
„ selection, 80-3

„ „ teleological, 370

„ union, reasons for, 256
Shad, the, 173
Shamming death, 193, 216
Shell of the snails, origin of the, 241
Silurian strata, animals in the, 121
Skeleton of the articulates, 203
Skull, development of the, 153
Smooth adder, the, 14 1
Snail, the, 239
„ breathing of the, 244
Snails with small shells, 168
Snipe, noise of the, 96
Social instincts, culture of, 408
„ instinct in birds, 112
Society, growth of, 407
Sociology, 406

„ laws of, 407
Species, nature of a, 33, 1 1 7

persistence of, 132-3, 135

INDEX

435

Species, characters of, 93-5
Spencer, H., on play, 62
Spermatozoa, 255, 303
Spider, the, 217

„ pairing of the, 197
Spiracles, 185
Spiritual world, the, 388
Spontaneous generation, 315, 317
Spring as the love-season, 57
Squirrel, winter store of the, 56
Stag, antlers of the, 84, 89, 207-13
Stag-beetle, the, 89

,, larva of the, 219
State, Nietzsche’s idea of the, 417
Stegocephala, the, 121
Steinheim snails, the, 125
Stickleback, the, 174
Stigma, the, 197
Sting of the bee, 221
„ of insects, 193
Stirner, Max, 416
Stork, the, 46

„ noise made by, 96
Strepsitera, 202
Struggle for life, the, 25, 27
Styloid bones, 157
Sty lops melitta, 202
Subjectivity of knowledge, 405
Sudden changes in nature, 13 1
Survival of the fittest, 28
Swimming-bladder of fishes, 150-1
Symbiosis, 284

Tadpole, the, 21
Tania echinococcus , 281
Tania saginata, 279, 280
Tania solium, 279, 280
Tape-worm, the, 279-82

„ development of the, 26-7

„ eggs of the, 26

Teleological principles, 352
Teleology, 364

Temperature of ancient Europe, 1 19
Thing in itself, the, 387
“Thus spoke Zarathustra,” 421
Tibia, the, 168
Tiger-moth, the, 190
Toad, age of the, 149
,, secretion of the, 146
Tortoise, the, 143

Tortoise-shell butterfly, the, 189, 191,
193

Tracheae, 184
Tradition, 41 1
Trance, 233
Transformism, 37
Transitional forms, 264
Tree of life, the, 37

Tree-frog, the, 148
Tree-locust, the, 185
Trichina, the, 276
Tropical frogs, 119
Trout, eggs of the, 26
Trunk-fish, the, 177
Truth, the will to attain, 427
Turkey, the, 88, 89
Types of animals, 132

Ultimate concepts, 394
„ elements, 379, 381
Universal concepts, 380
Unnucleated organisms, 308
Uric acid, 351

Use and disuse, effects of, 223, 225

Value, idea of, 413

„ no standard of, in science, 375
Variations are in all directions, 368
, , not definitely directed, 369

,, in organisms, 40

,, plus and minus, 162

,, roots of, 334

Variety, nature of a, 33
Vermiform appendage, 158
Vertebrates, similarity of, 153
Viper, the, 140
Vital force, 355
Vitalism, 350
Voluntary action, 214
Volvox, the, 297
Vorticellas, 293

Wallace, Dr. A. R., on sexual
selection, 81

War-dance of animals, 89
War, evils of, 415
Wart-hog, the, 89
Wasmann, Father, 38
Wasps, predatory, 218
Water-beetle, the, 218
Water-flea, the, 20, 22, 229, 236, 252
Water-ousel, the, 97
Water-polyp, 284
Wasmann on co-adaptations, 213
,, on heredity, 299

,, on instinct, 64

,, on the extinction of

species, 127

Whale, rudimentary organs of the,
159

Wild cocks, 91
Will to live, the, 356
■Willow, fertilisation of the, 198
Willow-wren, song of the, 96
Winged horses, possibility of, 369
Wings, 100

43 ^

INDEX

Wings, evolution of, 136-7, 157
Winter sleep of animals, 55-7
Womb, development in the, 59-60
Wood-chat, song of the, 97
Woodpecker, the, 18, 21

„ noise of the, 96
Work and play, 61

,, mental and physical, 61-2

World, infinity of the, 390
Wren, the, 97

Xylina vetusta , 193, 216 .

Yellow as warning colour
Yolk of the egg, 247, 304

Zoea, 251

THE END

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Class ' Book

Aec. 8 <> 432 »™. . Copy

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