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AUTHOR:

HERBERT, SOLOMON

TITLE:

THE FIRST
PRINCIPLES
OF EVOLUTION

PLACE:

LONDON

DATE:

1913

COLUMBIA UNIVERSITY LIBRARIES
PRESERVATION DEPARTMENT

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Herbert, Solomon, 1874-

Tlie first principles of evolution, by S. Herbert ... con-
taining ninety illustrations and tables. London, A. and
C. Black, 1913.

viii p., 1 1., 346 p. 1 illus., plates (1 coL) tables (1 fold.) 20i
"Literature" : p. 319-326.

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1. Evolution.

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THE FIRST PRINCIPLES OF EVOLUTION

BY THE SAME AUTHOR

THE FIRST PRINCIPLES

HEREDITY

COXTAIXIXG 75 DIAGRA^rS AND ILLUSTRATIONS

Large Crown 8vo., cloth
Price 5s. net (by post ss. 4d.)

"Dr. Herbert has produced a bnok which we
think will be widely read and will al-o serve its
original purpose as a textbook for elementary
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without any superfluous wordiness, and conveni-
ently divided into sections. The diagrams and
illustrations adopted from various sources have
been judiciously chosen, and do much to throw
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THE FIRST PRINCIPLES

EVOLUTION

S. HERBERT

M.D. (Vienna). M.R.C.S. (Engl.), L.R.C.P. (Lond.)

AUTHOR OF "THE FIRST PRINCIPLES OF HEREDITY"

CONTAINING NINETY ILLUSTRATIONS
AND TABLES

LONDON
ADAM AND CHARLES BLACK

mmtm'i

' Jmrnr

51 S

I 1

v*V

PREFACE

This book, like a previous one, '*The First Principles of
Heredity/' is the outcome of a series of lectures given to a
class of working-men and others. Though there are hosts
of books dealing with Evolution, they are either too com-
pendious and specialized, or, if intended for the average
reader, too limited in their treatment of the subject.
Indeed, there exists no textbook which presents the
problem of Evolution comprehensively in all its aspects.
To do this in the following pages in a simple, yet scientific
manner, and thus to supply a real want— the only excuse
for a new book— has been my aim.

The task of embracing in one survey so many fields of
science has proved an immense one, and I must therefore
crave the indulgence of the critical reader of this book
for its unavoidable imperfections.

I cannot omit expressing my great indebtedness to my
friend David Isaacs for his unwearying help, so un-
grudgingly given, in the preparation of this work and its
predecessor.

S. H.

Manchester, March, 191 3.

CONTENTS

INTRODUCTION
Chapter I. EVOLUTION IN GENERAL

PAGE
I

SECTION I.— INORGANIC EVOLUTION

Chapter H. THE EVOLUTION OF MATTER - - 7

1. COSMIC EVOLUTION - - - - * 7

2. GEOLOGICAL EVOLUTION - • - * ^7

3. ATOMIC EVOLUTION - - - - 'SO

4. EVOLUTION OF LIFE - - - - • 43

SECTION II.— ORGANIC EVOLUTION

PART I.— THE FACTS OF EVOLUTION

Chapter III. MORPHOLOGY - - - - $2

1. HOMOLOGOUS STRUCTURES - - - * 54

2. RUDIMENTARY STRUCTURES - - - '59

3. VESTIGIAL STRUCTURES IN MAN - - ' ^3

Chapter IV. EMBRYOLOGY - - - - 69

1. EMBRYOGENY - - • - * 7'

2. THE BIOGENETIC LAW - • - "74

Chapter V. CLASSIFICATION - - - - 83

Chapter VI. PALEONTOLOGY - - - - 89

Chapter VII. GEOGRAPHICAL DISTRIBUTION - - 99

vii

••tfiiimfm^Mimmmmmmtm

Vlll

CONTENTS

PART II.— THEORIES OF EVOLUTION

PAGE

Chapter VIII. THEORIES OF EVOLUTION - - 107

1. HISTORICAL - - - - - ' - . 107

2. LAMARCKISM - - - - - III

3. DARWINISM - - - • - - 117

A. NATURAL SELECTION - - - ' ^^7
ADAPTATIONS - - - - - 124

(a) PLANT STRUCTURES - - -125

(6) ANIMAL COLOURATION - - " 13^

{d) HUMAN FACULTY - - - -157

{e) DEGENERATION - • • "159

B. SEXUAL SELECTION - - - - 163

4. DIFFICULTIES OF THE THEORIES - - - 1 72

A. NEO-LAMARCKISM - - • -175

B. NEO-DARWINISM - - - - 1 78
AUXILIARY THEORIES OF NATURAL SELECTION - I90

(a) PANMIXIA ----- 191

{b) INTRA-SELECTION - - "193

(d) COINCIDENT SELECTION - - - 197
{e) ISOLATION - - - - - 1 98

CHAPTER IX. THEORIES OF EVOLUTION— Cow/mw^rf - 205

1. HETEROGENESIS ----- 206

2. ORTHOGENESIS - - - - - 214

{a) MECHANISTIC THEORIES - - - 214

(b) VITALISTIC THEORIES - - - - 21 8

3. CONCLUSION - - - - - - 223

CONTENTS

Chapter X. SOCIAL EVOLUTION— Con/«w«^(f

2. MORAL EVOLUTION - - . -

{a) ANIMAL ORIGINS ...
(6) HUMAN DEVELOPMENTS

3. EVOLUTION OF MAN - - -

4. EVOLUTION OF SOCIETY - - .

A. THE FAMILY - - - -

(a) THE PATRIARCHAL THEORY

(b) THE MATRIARCHAL THEORY

B. THE STATE - - - .

(a) PRIMITIVE COMMUNISM -

(b) FEUDALISM AND ITS OUTCOME -

C. RELIGION - - - .

(a) ANIMISM - . . -

(6) OTHER THEORIES

APPENDIX^ A PRECIS OF SCIENCE

D. EVOLUTION AND PROGRESS

CONCLUSION

Chapter XI. THE FORMULA OF EVOLUTION -

1. EVOLUTION - - - - -

2. DISSOLUTION - • -

Chapter XII. THE PHILOSOPHY OF CHANGE -

Literature ..-.--
Glossary .....

Index - . - - •

PACK

247
249

253
258
271
272
272
274
278
280
280
284
288
289

293
297

298

305
306
313

316

319
327
337

SECTION III.— SUPERORGANIC EVOLUTION

Chapter X. SOCIAL EVOLUTION -

I. MENTAL EVOLUTION - - -

(a) BEHAVIOUR OF LOWER ORGANISMS
(6) INSTINCT - - -

{d) REASON -

226

226
227

235
240

244

••mm

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im. mniii —in. mi -1^ i.i iiwi.

THE FIRST PRINCIPLES OF

EVOLUTION

INTRODUCTION

CHAPTER I

EVOLUTION IN GENERAL

There is perhaps nothing more significant of our age than
the change which has taken place in our conception of the
universe. The old notion of eternal unchangeableness,
with occasional upheavals— the static view— has given
way to the newer idea of progressive development in nature.
Gradually, within the last half-century, this new inter-
pretation, which regards all things from the evolutionary
or dynamic point of view, has extended from one field of
human inquiry to another, creating everywhere fresh
interests, giving novel aspects to old problems — nay,
colouring and transforming the whole purpose and meaning
of modern Hfe. At last we seem to be on the threshold
of nature's long-kept secret. After ages of darkness, the
first gleam of a deeper understanding of her intentions has
dawned upon us. Showing as it does the small beginnings
of all things, their gradual transformation, step by step,
towards higher stages of perfection, this new philosophy
has opened out to us new possibilities, new visions and
aspirations. It takes in with one grand sweep aU the
phenomena of existence, and stands as the embodiment of
a new ideal which cannot fail to widen our outlook upon life.

2 THE FIRST PRINCIPLES OF EVOLUTION

For this end it is necessary not only that we should
know a few isolated facts of evolution, but that we should
digest and thoroughly understand its principle ; in short,
we must learn to think in terms of evolution.

But what is evolution ?

Though the doctrine has been before the world for over
fifty years, and has become an accepted fact of science, the
general public still has only a very hazy notion of it and
all it involves. It is often thought to imply nothing more
than the belief in " the descent of man from monkey '* ;
or sometimes people somewhat better informed will go so
far as to connect it with the theory of the Origin of Species,
propounded by Darwin. As usual, the popular fancy has
seized on the most outstanding feature of the doctrine
of evolution. We must make clear from the outset
that evolution, properly understood, is neither the one nor
the other of these theories, but rather includes, as we shall
presently see, immeasurably more than both.

As we term the growth of the individual his develop-
ment, so we call the development of the cosmos from a
simple primitive state to complex and higher states its
evolution. The unending process of evolution is a uni-
versal phenomenon, a fact of nature, for which an ex-
planation is attempted in the various theories of evolution.
Evolution and the theory of evolution are accordingly not
identical terms, the first being a process of nature, the
second a hypothesis or theory, formulated to explain this
process.

That the universe is not static, but is, on the contrary,
undergoing a continual change, is a truth which had
already dawned on the ancient Greeks. " Flux or move-
ment," said Heraclitus, " is the all-pervading law of things."
After the passing of the dark Middle Ages, the idea of the
gradual transformation of all the forms of life found ex-
pression here and there, but without gaining any wide
acceptance. It is only when we approach our own times
that we find the principle of evolution established on a

EVOLUTION IN GENERAL 3

scientific basis. Erasmus Darwin, Lamarck, and others
had made ineffectual attempts towards a solution of the
problem ; but it was Charles Darwin who, in his book on
the " Origin of Species," at one stroke not only offered
an acceptable theory of the transmutation of species, but
firmly established the fundamental principle of evolution.
Since that time the world has become more and more
convinced of the correctness of that principle ; though,
as we shall see later, this can by no means be said of the
special theory which Darwin advanced as an explanation
of organic evolution — a vital point which has already been
alluded to, and which has to be carefully borne in mind
by the reader.

For Darwinism, or the theory of evolution as pro-
pounded by Darwin, refers only to organic evolution — i.e.,
to the evolution of plants and animals. His epoch-making
book, which appeared in 1859, explains, as the title in-
dicates, the " Origin of Species by Means of Natural
Selection." It must therefore be understood that Darwin-
ism is not identical with evolution, but is a theory, — and a
theory of organic evolution only. Still less can evolution
be taken to be synonymous with the descent of man from
the ape ; for the descent of the species man from the lower
animals is only a particular case of the origin of species.
Evolution in the fullest sense covers a much wider field ;
it is coterminous with the whole range of cosmic phenomena.
It holds good not less of the great stars, millions of miles
away, than of the tiny microbes barely discernible under the
highest magnifying power. By its light we are enabled
to decipher the ancient history of suns and planets, of our
earth, and all it contains ; we can explain the onward
path of all things existent, and to a certain extent foretell
their further progress.

To have discovered a unifying principle of such far-
reaching application, covering such various phenomena,
to have given us the grand conception of a world-embracing
evolution, is the great achievement of Herbert Spencer.

A^^^e^i^. -■■>fe''A<^".»a,y-.fe;:<jS,. .:■

[II
I

4 THE FIRST PRINCIPLES OF EVOLUTION

Not only was he the first independently to adopt the
evolutionary principle as a means for the solution of various
problems of matter and mind, actually anticipating Darwin's
discovery by a few years— a fact very little known by the
general public — but he gradually elaborated a complete
theory of evolution, comprising in one great formula the
law of all existence. Dealing in his " First Principles '*
(ist edition, 1862) with the general aspect of the problem
of evolution, he completed the tremendous task of working
out all the successive sections of his great " Synthetic
Philosophy *' in full, applying the *' master-key of evolu-
tion " in turn to the phenomena of life, the problems of
society, and last, but not least, to the fundaments of
ethics. " Indeed, this last part of the task it is," he writes,
to which I regard all preceding parts as subsidiary/'
To find for the principles of right and wrong a scientific
basis " is, he declares, his ultimate aim.

And here we are face to face with the profound impor-
tance of the results flowing from the scheme of evolu-
tionary doctrine. Giving us a unifying principle for
the totality of manifestations, and recognizing the con-
stant transformation of all things, spiritual as well as
material, through a never-ending series to higher and more
perfect states, it is specially suited to deepen our inmost
sense of life, making us tolerant towards the past and hope-
ful of the future.

€1

SECTION I
INORGANIC EVOLUTION

Nature is one and indivisible. She knows nothing of
the categories we are wont to make in order to render her
understandable to ourselves in parts. We are apt to over-
look this truth when we apply ourselves to the study of
any definite range of phenomena ; we so easily forget the
connections which exist between the dilfferent manifesta-
tions of the universe. For, it must be understood, all
these distinctions are of our own making — they are ab-
stractions se-ving the useful purpose of defining the
separate parts of our human knowledge. Of this unity in
diversity science has at last become fully conscious, ever
since the theory of evolution opened out to us the possi-
bility of combining under one principle all natural phe-
nomena, which had appeared until then as so many frag-
mentary records of an inscrutable whole. The hitherto
isolated facts of nature have become, thanks to Herbert
Spencer, comprehensible from one common point of view.
He applied, as already mentioned, this new central idea of
progressive development to all phases of existence ; and
in the exposition of the succeeding pages we shall have
to follow largely the masterly account of his doctrine
laid down in his " Synthetic Philosophy."

It is customary to divide the whole realm of nature
into two great parts : the inorganic and the organic. The
former comprises all lifeless things, as stones, rocks, planets,
suns, etc. ; the latter contains the living beings with more

6 THE FIEST PRINCIPLES OF EVOLUTION

or less differentiated parts (organs), from the lowest plants
to the highest animals, including man. In addition to the
facts presented by organic bodies taken singly, there are
certain other phenomena, such as constitute the social life
of a community, which are the result of the aggregation
of a number of organisms. These phenomena were called
by Herbert Spencer '* superorganic." In dealing, then, with
evolution, we shall treat it in three separate sections —
namely, (i) inorganic, (2) organic, and (3) superorganic
evolution.

i/«:

CHAPTER II

THE EVOLUTION OF MATTER

Before entering into the subject proper of inorganic
evolution, we must remark that whatever we may be able
to find out about the evolution of matter, we must take its
somehow-existence for granted. Evolution only traces
back the transformation of matter through its various
stages ; it does not at all pronounce as to an original creation
of matter out of nothing.*

Starting, then, with the world-stuff as given, we shall
discuss (i) the evolution of the universe, or cosmic evolu-
tion ; (2) the evolution of the earth, or geological evolu-
tion ; (3) the evolution of the chemical elements, or atomic
evolution ; and (4) the evolution of organic forms from
inorganic matter, or the evolution of hfe.

I. Cosmic Evolution.

It has ever been the natural tendency of man to assign
to himself a unique position in the scheme of creation,
which he is but slowly being forced to abandon by the hard
facts of science. To the ancients the earth, the abode of
man, was the centre of the universe, and around it the sun,
stars, and planets moved in their courses. This idea pre-
vailed until deep into the Middle Ages. It was only in
the sixteenth century that Copernicus finally overthrew
the old Ptolemaean geocentric system by showing that
the movements of the heavenly bodies could be accounted
for much more plausibly by assuming the earth, in common
with the other planets, to revolve round the sun as a fixed

* We shall see later on that the evolution of matter out of
electrical units is the latest subject of speculation.

8 THE FIRST PRINCIPLES OF EVOLUTION

centre. About a century later Kepler discovered the
famous law of motion, according to which the paths or
orbits d*?scribed by the planets around the sun are not
circk^, as was previously supposed, but ellipses. The
heliocentric theory of the solar system, then, posits a
mighty central sun (866,000 miles in diameter), and
round it, coursing at various distances of miUions of miles,
the planets, all many times smaller than the sun, each
accompanied in its turn by one or more sateUites, which
move round their primaries according to the same law of
motion. But this solar system of ours is, as is well known,
only a very «^mall portion of the entire visible universe.
For, as will appear later, the sun is nothing but a star, and
there are known to the astronomers at least a hundred
millions of stars, the nearest of them many billions of miles
away from our sun, each star having, in all probabihty,
mightier and vaster systems than our own. These, in-
cluding the passing comets and shooting stars, were con-
sidered to form the whole contents of the heavenly spheres,
until at the end of the eighteenth century Sir William
Herschel, by his extensive observations on nebulae, showed
tliem to be an integral part of the cosmic system, thereby
opening a new outlook into the constitution of the universe.
Though faint luminosities in the heavens had been observed
before his time, it was he who, by a systematic study of the
nebulae, was enabled to bring them into Hne with the other
stellar phenomena ; indeed, he first gave scientific evidence,
by means of his improved telescopic methods, of a
hypothesis which had already been advanced before him on
merely theoretical grounds, independently by the German
philosopher Kant and by the great French mathematician
and astronomer Laplace. This Kant-Laplacean theory,
which is generally known as the '* nebular hypothesis,"
we shall now deal with more in detail.

COSMIC EVOLUTION 9

{a) The Nebular Hypothesis.

It is a somewhat startling fact in the history of evolu-
tion to find that the first successful attempt of applying
the principle of progressive development in nature was
made with regard to celestial bodies which are millions
and millions of miles away. The nebular theory first
suggested by Kant in 1755, and afterwards worked out
more fully by Laplace in 1796, has been amply confirmed
by later scientific researches, and still holds the foremost
place as an explanation of the origin of the solar system.
According to Laplace, the matter which now constitutes
k our solar system — i.e., the sun, planets, and their satelUtes

K — was once, aeons ago, a vast mass of intensely heated gas,

\ extending beyond the confines of the orbit of the outer-

most planet, Neptune, a radius of nearly three thousand
million miles. This rarefied *' fire-mist," millions of times
more tenuous than air, was, in fact, at that time nothing
else than a nebula, such as can be observed by the thousand
in the heavens with our improved telescopes. If there was
any doubt left as to the true nature of such a nebula, the
marvellous advancement of astrophysics has been able to
set that at rest. For by means of spectrum analysis the
constitution of the heavenly bodies coursing at such
enormous distances can be analyzed as certainly as if we
had them in our chemical laboratories.

It is a well-known fact that sunlight, when passed
through a prism, is spread out into a beautiful coloured
band or spectrum, exhibiting all the colours of the rainbow
from red on one side through orange, yellow, green and
blue to violet on the other. When suitably examined,
this continuous spectrum of the sun can be seen to be
crossed by a great number of dark lines, constant in posi-
tion and relative intensity, which were first detected by
Fraunhofer in the beginning of the nineteenth century, and
are since known as *' Fraunhofer lines." Kirchhoff was first
able, in 1859, ^^ §^ve the meaning of these lines. He

im^jm^''' 'igggr

•■■■■■■I

8 THE FIRST PRINCIPLES OF EVOLUTION

centre About a century later Kepler discovered the
Sio^ law of motion, according to which the i«ths or
orbits described by the planets around tte sun are not
circles, as was pre%nously supposed, but eUipses. The
SUntric theory of the solar system. *!>«". P^-^^J
mighty central sun (866.000 miles in «iiameter), and
rom»d it coursing at various distances of milhons of miles
Ihe planets, all many times smaller than the sun. «ich
accompanied in its turn by one or more sateUites. which
move round their primaries according to the ««me law of
motion. But this solar system of ours is, as is weU Imown.
only a very ««iaU portion of the entire visible universe.
For as will appear later, the sun is nothing but a star, and
there are knovnTto the astronomers at least a hundred
millions of stars, the nearest of them many biUions of mJ^
away from our sun, each star havmg. m all probability,
mightier and vaster systems than our own. These, m-
cluding the passing comets and shooting stars, were con-
sidered to form the whole contents of the heavenly spheres,
until at the end of the eighteenth century Sir WiUiam
Herschel by his extensive observations on nebulae, showed
them to be an integral part of the cosmic system, thereby
opening a new outlook into the constitution of the universe
Though faint luminosities in the heavens had been observed
before his time, it was he who, by a systematic study of the
nebula, was enabled to bring them into hne with the other
stellar phenomena ; indeed, he first gave scientific evidence,
by means of his improved telescopic methods, of a
hypothesis which had already been advanced before hun on
merely theoretical grounds, independently by the Gennan
philosopher Kant and by the great French mathematician
and astronomer Laplace. This Kant-Laplacean th^ry,
which is generally known as the nebular hypothesis,
we shall now deal with more in detail.

COSMIC EVOLUTION 9

(a) The Nebular Hypoihesis.
It is a somewhat startling fact in the history of evohi-
tion to find that the first successful attanpt of applying
the principle of progressive development in nature was
made with r^ard to celestial bodies which are millions
and milhons of mUes away. The nebular theory first
suggested by Kant in 1755. and afterwards worked out
more fuUy by Laplace in 1796. has been amply confirmed
by later scientific researches, and still holds the foremost
place as an explanation of the origin of the solar system.

According to Laplace, the matter which now constitutes
our solar system— ».«., the sun. planets, and their satellites
—was once, seons ago. a vast mass of intensely heated gas,
extending beyon<i the confines of the orbit of the outer-
most planet. Neptune, a radius of nearly three thousand
milHon mUes. This rarefied " fire-mist," milhons of tunes
more tenuous than air, was. in fact, at that time nothing
else than a nebula, such as can be observed by the thousand
in the heavens with our improved telescopes. If there was
any doubt left as to the true nature of such a nebula, the
marvellous advancement of astrophysics has been able to
set that at rest. For by means of spectrum analysis the
constitution of the heavenly bodies coursing at such
enormous distances can be analyzed as certamly as if we
had them in our chemical laboratories.

It is a well-known fact that sunlight, when passed
through a prism, is spread out into a beautiful coloured
band or spectrum, exhibiting all the colours of the rainbow
from red on one side through orange, yellow, green and
blue to violet on the other. When suitably examined,
this continuous spectrum of the sun can be seen to be
crossed by a great number of dark Hues, constant m posi-
tion and relative intensity, which were first detected by
Fraunhofer in the beginning of the nineteenth century, and
are since known as " Fraunhofer fines." Kkchhoff was firet
able in 1859, to give the meaning of these fines. He

THE FIRST PRINCIPLES OF EVOLUTION

showed that light ^J^^^^liTe^!^ ^S
made gaseous by 1"^^^^^^^^^^^^^^^^^ ^^^

a spectroscope (an ^"^"^'J^^^J ^„ ^ ^ark background-
lenses), gave bnght '^o^^'ffj.^^.^^trum-each element
?^ 'IhatcS bT'SnyS'nnes which were

r ^" t TnTrrinlStT^he'te^ce of the

^•"'' T.lemicaf substances in the sun. The Unes appear
various chemical suDsia atmosphere surroundmg

dark, because the hot vaporous a P spectrum,

the sun, which by >^sel gives a^ bnght P^^^.^^

absorbs-^.., extm^ishes ^^ ^^^

from the still hotter wmte ^^^ ^^^ ^^^^^ ^f

We are therefore «i^Wed t ^^^^^^^ ^^ ^^^ ^^^ ^^
any g^v^n ^^dy howev ^^^^^ ^^ ^^_j.^^ ^^^^^^

spectrum it g^^es- A^^ , . ^ continuous spectrum
indicates an incandescent g^^ ; ^^^ „, Uq^id

rtfor a^^ls^ourbSy unler high pressure) ; while the
a^Sir of S lines f^^^^^l^^^^
L"etf bo^ "iStrJ S»^^^^^^ for the

that they give a uug _JLther eas not yet found on

llStralidTovisio^^^^^^^^^^^^ /^t ^

SrsprLd L flat and .Uting j;^J e -e .r.t.n

:LrpS:ta7yrrld. irroUng would take place in this
of our Plan^J^^y ^ the radiation of heat mto space,

intensetyhot v^stmas^Dy ^^^ .^^ outermost

^'^^ tS olrts toSin consequence detach themselves
equatorial P^"^*^ J^'^'^. ^o the rings seen in the planet
raturrit\"fStr sU:\his rLg would cool and

,♦ /

a
o

H
O

w
z

o ^

<
OS

X
H

H OS

O CQ

C/)

D
O
D
Z

H
Z

D
O

O
d
z (d

H
Z

o
o

en —
^ X

U Ci H

M N

COSMIC EVOLUTION

condense into a liquid or soUd. As the cooUng would not go
on Somly in aU parts of the ring, it would break up and
tend to aggregate into a globular mass, forming a planet
TWs procfss iould not only repeat itsf successively in
the main parent mass, thus leading to the fonnation of
the different planets coursing round the central remaamng
body as a sun, but the planets themselves, being fiery baUs,
would throw off their own satellites in a similar manner

This theory of the formation of the sun and aU its
attendant bodies out of one original nebula accounts m
a most simple and satisfactory manner for a host of phe-
nomena exhibited by the solar system It expkins the
facts • (I) That the sun and larger planets are much hotter
than the earth and smaller planets, for the larger the mass
of a body the longer it takes to cool down ; (2 that the
motion lithe planets and their attending satelhtes is m
the same direction ; (3) that the rotation of the^^ different
bodies, including that of the sun. on their o^n ax^s ^s m
the same direction; (4) that the orbits of these different
bodies are nearly in the same plane ; (5) ^^ *!^.X\^;
being originally a rotating fluid mass, is flattened at both
poles and bulged out at the equator etc
^ Further proof has been forthcoming of late ; ]flf'^
whole science of stellar evolution may be ^aidto hav
resulted from the application of this ruitful hypoth J's
Not only have nebute been found m all s ages o deve op
ment from the diffuse nebula in Orion (Fig 2) through
greater and greater condensation to planetary nebulae
Sich appear'Iike bright discs, but the stars themseves
give evidence of their birth from these i^chular masses
indeed, there are nebulous stars, still surrounded by a sort
of glow of nebulosity, while spectroscopically sta s can
be arranged in a continuous series according to their age.

. According to the newest theory, by Professor G- H. Dax^Mt^
liquid or nearly solid.

THE FIRST PRINCIPLES OF EVOLUTION

i|!

A =t,r. takP their origin from a hot incandescent gas which
fs ?ali coXg'down and condensing, we shouW
L'urly find that stars in the earUer stagey wou^b
hcHpr than those of a more advanced type. The nottesi
stars a e wiSe. With gradual cooling down the cobu
S the stars changes to orange, yellow and f^^fy^
,« a heated iron cools from a white heat througn yeuow
to red with the decrease of temperature Furthermore
n the immense heat prevailing in these glowing stars aU
substances are vaporized and broken up mto their con
SuentXentsf nay. the elements themseve^ as wiU
aoDear later, are dissociated-t.e.. spht up into their more
Stive unts. It follows that the earUer the evolutionary
K S a Ttar. the more primitive will be its constituents
and the simpler its spectrum. .

The classification of stars is by no means simp c. and has
norbeen definitely settled. But on the whole four stages
can be distinguished. We have, firstly, the earliest s ar ,
Se those of^he Trapezium in the Orion nebula, which
seem intimately connected with the surrounding nebular
ZZ and have the most primitive spectrum showing on^^
The hel^m and hydrogen lines. After these come he
white or bluish-white stars, like Sirius, which give the
lines of hydrogen, and in addition, faint hncs of iron, sodium
magnesium, e'tc. At first the shrinking of the stars which
Takes place, more than counterbalances the loss of heat due
to radiation, so that in the beginning the stars grow hotter
instead of cooler. But ultimately a stage is reached when
cooling of the outermost parts goes on rapidly enough to
lead to their condensation. These stars show, in conse-
quence, an orange or yellow colour, their spectrum giving
faint hydrogen lines, while the metallic fines become more
pronounced. (Our sun, which, as we have said before, is
nothing but a star seen from a relatively short distance,
belongs to this class.) Finally, we have the red stars in
the declining age, showing a very complex spectrum.
The appearance of the planets, too, depends, as already

Fig. 2. — Diffuse

{^'

roin

Nebula in' Urion
" Problems in Astrophy

Orion (W. H. PiCKERixn),

by Agnes M. Cicrh)

COSMIC EVOLUTION

mentioned, on the stage of their development. We know
that the earth has sufficiently cooled down to have
a solid crust and a cool atmosphere, which made the
evolution of organic life possible ; while the much larger
planet Jupiter is still a glowing ball surrounded by an
intensely hot, vaporous envelope. The moon, on the
other hand, much smaller than both these planets, has long
since cooled down completely, and is now barren and
atmosphereless.

The ultimate question arises : Whence these nebulae ?
We can only surmise. The generally accepted idea is that
they are due to the collision of two mighty celestial bodies.
The heat generated by their tremendous impact would be
sufficient to dissipate both of them into thin vapour,
forming the substance of a new nebula.

It must be added finally that the large nebulae usually
observed have not given rise to such a small system as
ours ; they represent rather a system of such systems.

Though, as we have seen, the nebular hypothesis bnngs
into one harmonious scheme many phenomena of cosmic
evolution, still, many facts have been forthcoming which
are not in agreement with this theory. Of these we shall
only mention the principal ones :

I. The formation of coherent rings has been doubted,
because, according to dynamical principles, it would be
more likely that the outermost portions would separate
particle by particle.

2 According to Professor F. R. Moulton, the drawing
together of the ring material into a spheroid to form
a planet meets with great mechanical difficulties.

3 If the planets were formed in this manner, they should,
as Professor Faye has shown, rotate in the opposite direc-
tion to that of their primaries.

4 While the satellites accompanying the earth, Mars
and Jupiter, and eight of the satellites of Saturn, revolve,
in accordance with the theory, in the same direction as
their planets, the satellites of Uranus and Neptune, and

14 THE FIRST PRINCIPLES OF EVOLUTION

the newly discovered ninth sateUite of Saturn, revolve in
the opposite direction.

«5 The planes of the orbits of the four satelhtes of
Uranus are almost perpendicular to the plane of the planet s

"^^^ 'According to the nebular theory, the loss of heat
leads to contraction, and in consequence thereof to a con-
stantly accelerated rotation of the planets. It follows
from this that, as the satellites are thrown off at an early
stage of the planet's existence, the time taken for a revolu-
tion of the satellite round its primary should be longer
than the time of rotation of the primary round its own axis ;
but Phobos, one of the satellites of Mars, revolves in less
than a third of the time of the planet's rotation.*

7. Serious dynamical objections, too technical to be
discussed here, have been raised by Professor Moulton.

8. Finally, and this is perhaps the weightiest argument
against the theory, no nebula have been found with rings,
the only heavenly body with ring formation being Saturn.
On the contrary, the discoveries of Professor Keeler have
shown that out of nearly a hundred and twenty thousand
nebulae now recorded, by far the greater number are spiral
in form, a fact with which we shall deal presently.

It would appear, then, that grave difficulties stand in
the way of the complete acceptance of the nebular theory
as propounded by Kant and Laplace ; indeed, as has just
been mentioned, it does not take account at all of the
majority of nebuL^, which, with the modern powerful
instruments, have been found to exhibit a typical spiral
structure. Professors Th. C. Chamberlin and F. R.
Moulton have advanced a new hypothesis as to the origin
of our solar system more in accordance with modern
knowledge. To this we now turn.

* This objection has been met by Professor G. H. Darwin, who
explains the difference as due to tidal retardation of the rotation of
Mars.

COSMIC EVOLUTION

{b) The Planetesimal Hypothesis,
The starting-point of the solar system, according to
this theory, is a spiral nebula, which is, as has just been
said, the most common type observed. Such a nebula,
as Fig. 3 well illustrates, shows a distinct central mass
around which are coiled two long arms, which give the
impression of having been produced by rotation of* the
whole mass, though sufficient time has not yet elapsed for
proving such rotatory movement by actual observation.
On the arms " knots " or partial concentrations of matter
can be distinguished. The whole spiral is more or less flat,
lying, when seen edgewise, in one plane. The spectrum
of these nebulae is continuous, thereby proving that we have
to deal, not with a finely dispersed gas, but with either
Hquid or, more probably, solid bodies. There seems to
be no doubt that we have in these nebulae aggregates of
small bodies revolving round a common central mass,
and immersed in a more tenuous medium. These bodies
have been called " planetoids " or " planetesimals," on
account of their resemblance to the planets, the theory of
their origin and further evolution being the Planetesimal

Theory. .

It would appear, then, that we have m such a spiral
nebula the rough outUne of a planetary system, in which
the process of further development is a relatively simple
one. The knots forming the nuclei of the future planets,
and coursing in their orbits around the central body,
aggregate by coalescing into larger and larger masses, the
planets gathering up at the same time the remnants of
nebulous matter, while the central body remains the
controlling sun. It follows from this that the planets are
at no time of their life-history entirely gaseous, but rather
cool, solid bodies, including a greater or smaUer amount of

gaseous matter.

As to the origin of the spiral nebula, it has been ex-
plained by Professor Moulton as due to the effect of the tidal

i6 THE FIRST PRINCIPLES OF EVOLUTION

action of two more or less spheroidal nebute on each other
Given two such rotating bodies approaching near to each
other without colliding, the effect of the mutual attrac ion
on luch loosely aggregated bodies would be an eongation
of the main masses, the formation of bulging parts at the
Lo opposite poles, and the final disruption of these po-
tuberances into long streamer-hke arms, which, on account
of the rotatory movement of the whole "^a^s ^uld tend
to coil closer and closer round the centra body These
coils would cool down through rapid "-adiation, and con-
dense at various points into knots, forming finely divided

solids and planetoids.

According to Chamberlin, the gaseous nebute have nothing
to do with the evolution of our planetary system, though
they may be connected with the origin of the stars. We are
thus left face to face with two theories of cosmic evolution,
which cannot be reconciled with each other ; nor does either
of them fit in at present with all the observed facts of
astronomy.

Sir N. LocKycr, and supported by Professor G. H. Darwin,
which we must briefly mention for the sake of complete-
ness though it has found little recognition among scientists.
According to this hypothesis, the original cosmic material
consists of meteorites. " Nebulae are really swarms of
meteorites in the celestial space. The meteorites are
sparse, and the colHsions among them bring about a rise
of temperature sufficient to render luminous some of their
chief constituents." The meteorites swarm indiscrimin-
ately in all directions, and with widely different velocities.
But Chamberlin has argued that if this is so, they must
soon be vapourized ; and therewith this theory would merge
into the gaseous one of Laplace. Furthermore, the mam
evidence of Lockyer, based on the appearance of a certain
characteristic line in the nebular spectrum, and attributed

Fig. 3. -Spiral Nebula (taken by Mr. W. E. Wilson. March 6, 1897).
(From ^^ Problems in Astrophysics," by Agnes M. Clerkc.)

.( t

Fjg. 3.- Spihai. Nicr.ULA (taken hv

Mr. W. ]•:. Wilson, March 6, i8<j7).

C-'roin " I'lvblcins ii

Astiopliysiis," by Aiincs M. Clerks-.)

■WPiiPWi^W

GEOLOGICAL EVOLUTION

-^1

by him to magnesium oxide, has broken down, as this line
is now generally interpreted as due to nebuHum, a gas
peculiar to nebulae, and not yet found on our earth.

We must point out here, in order to avoid misunder-
standing, that the inabihty to formulate at present one
thoroughgoing theory in explanation of steUar evolution,
does not mihtate in the least against the evolution of the
cosmos as a fact. The proofs of the latter are entirely
independent of any theory that may be propounded to
explain any particular method of evolution. We have
seen that the harmony of the observed heavenly phenomena
fits in well with a general scheme of cosmic evolution ;
and the time may not be far off when all these phenomena
will be brought into one comprehensive whole.

2. Geological Evolution.

The most primitive idea of the earth was that of a vast
extended flat disc, with the expanse of the heavens stretch-
ing over it like a mighty dome. This gave way in very
early times to the more correct interpretation of the earth
as a spherical globe poised in space, the sun and stars
coursing round it in their regular paths. The next stage
was reached when, as has already been pointed out in the
first part of this chapter, the centre of the whole system
was transferred from the earth to the sun. Of course,
there was at this period of geological history no possible
thought of a continuous development of the earth. The
most fanciful notions prevailed. The biblical theory of
creation held sway in place of scientific research. Fossils
were looked upon as " sports of Nature," and the belief in
a universal deluge which once overtook the earth and all
its inhabitants was general. Though here and there the
truth was guessed at— thus, among others, the famous
painter Leonardo da Vinci recognized fossils to be the buried
remains of once-existing animals, and Steno of Padua
(1669) deduced from the marine deposits of Tuscany the

attMifi

i8 THE FIRST PRINCIPLES OF EVOLUllON

successive configurations of that district— it was not until
the end of the eighteenth century that the Scotch geologist
Hutton (1788) promulgated . the first coherent theory of
geological formations. He was the first to explain the
former changes of the earth's crust by means of natural
^ forces only. According to him, " all past changes have
been brought about by the slow agency of existing causes."
Unfortunately his work met with great opposition for
rehgious reasons. Furthermore, he expounded a one-sided
theory of the formation of the rocks, attributing their
origin to igneous action only (vulcanism), in contra-
distinction to the so-called " Neptunists," who, led by the
German geologist Werner, supposed all existing rocks to be
due to a chemical precipitation from a *' chaotic fluid."
The true founder of modern geology is Charles Lyell, who
in his " Principles of Geology" (ist edition, 1830) elaborated
all the natural means now recognized as factors in earth-
sculpture. The wearing down of the high land by the
action of the rain and the atmosphere, the erosion of vaUeys
by streams, the encroachment of the waves upon the sea-
shore, and the deposition of the resulting debris either upon
lowlands or within the sea as sedimentary strata ; further,
the activity of volcanoes and underground waters ; — in fact,
the uniform action in all past ages of the same agencies
as can now be studied, determines, according to modern
geological science, the ultimate features of the face of the
earth. Not catastrophism, but slow and orderly develop-
ment, reigns in geological phenomena as in all other realms
of nature. The uniformitarian doctrine of Lyell, it is
true, recognized neither beginning nor end in the earth's
history ; but since then the new evolutionary ideas in con-
junction with recent astronomical discoveries have enabled
us to trace the earth's progress in a continuous line from
its first beginnings up to the latest stages of the present
time. Of these the early stages are in the nature of
the case largely hypothetical, while the later geological
formations of the earth have been worked out with more
definiteness and accuracy.

GEOLOGICAL EVOLUTION

(a) The Hypothetical Stages.

We have seen that, according to the theory of cosmic
evolution, the earth was born from a primeval nebula,
and revolves, with its sister planets, around the central sun.
We have further seen that in course of time the planets
pass through various phases, starting as shining white-hot
globes, and cooling down gradually to duU, non-luminous
bodies receiving their light from the central sun. Now,
we must assume the earth to have passed through all these
successive stages. Originating as a great fiery ball, our
globe, in whirling round its own axis, assumed its present
shape, being flattened at the two poles and bulged out at
the equator. On account of the enormous heat, all the
substances making up the planet would be vapourized, the
compound bodies being dissociated into their constituent
elements. Gradually, as cooling took place through the
radiation of heat into space, a molten mass would result,
the heavier metals, like iron, etc., gravitating towards the
centre, the lighter towards the surface, while the lightest
elements would form a vast atmosphere around it laden
with the waters of the future oceans and heavy with
carbonic acid (COg). The moon was thrown off, according
to Professor G. H. Darwin, by a tidal wave, from the earth,
while it was still in this plastic condition, which is reckoned
to have taken place about fifty-six to fifty-seven million

years ago.

With the further fall of temperature, the planet tended
to consolidate. It is still a moot point in science where
solidification first started. The opinion most widely held
assumes the interior of the earth to be an intensely hot,
partly gaseous, partly fluid mass ; though it must be under-
stood that at the enormous pressure which prevails at this
depth such a mass would behave practically like a rigid
body. According to this view, the surface of the globe
congealed first, forming a comparatively thin shell, which
gradually extended towards the centre. Lord Kelvin, on

p.^^:7«v.^a.w-^.-.6r«MB.«t«»..

20 THE FIRST PRINCIPLES OF EVOLUTION

the other hand, argued that with the high pressure at the
centre, the interior must have consolidated first. It must
not be imagined, however, that the primitive cmst was
smooth and uniform. Floating on a sea of fluid rock,
and exposed to mighty tidal waves and strong atmospheric
currents from above, it was repeatedly broken up into
enormous irregular slabs, and acquired stabihty only after
many successive corrugations.

The first permanent configuration assumed by the earth,
according to Professor J. H. Jeans, was pear-shaped (as if
the earth had been arrested in the protrusion of a second
body Hke the moon) ; the equator was not circular, but oval,
the broader end corresponding to the middle of the African
continent, while the stalked end formed an island— assumed
to have once been in existence in the midst of the Pacific
Ocean. With a further fall of temperature, the steam
suspended in the atmosphere Uquefied and settled on the
uneven surface of the land, thus giving rise to the first
oceans, which consisted of boiling water. The original
shape of the earth determined the primary distribution of
land and sea, the latter accumulating mainly round the neck
of the pear, forming a broad girdle of water round the globe
corresponding to the present Pacific Ocean.* As the con-
densation going on in the overlying atmosphere must have
been irregular, areas of high pressure and low pressure
ensued, with the result that the thin crust was corre-
spondingly depressed or raised. The soHd earth became
"dimpled and embossed," the water gathering in the
hollows. But the very distribution of land and water
would lead to a further differentiation of land and sea
level. For the enormous weight of the oceans, exerting a
steady downward pressure, would increase the oceanic
depression, while, on the other hand, the release of pressure
over the land area, produced by the withdrawal of the
dense, heavy, watery atmosphere above it, would tend to

* Later on the land hemisphere collapsed at the two sides, which
led to the formation of the Atlantic and Indian Oceans respectively.

GEOLOGICAL EVOLUTION

expand and elevate the crust. It must be understood,
however, that the early formation of continents has nothing
to do with the upheaval of gigantic mountain-ranges, which
appear at a much later period of the earth's history. We
have thus at last reached the final arrangement of the
accessible parts of the earth, the threefold zone of matter
encircling our globe— '* the lithosphere, or girdle of rock ;
the hydrosphere, or belt of water ; and the atmosphere, or
mantle of air "—the latter still dense and heavy, because
it contained all the carbonic acid that was later on used up
for the growth of the carboniferous forests, and all that
went otherwise into the formation of the rocks.

The further stages of the geological record consist,
henceforth, mainly in the alternate process of wearing down
the land surface and building up new rocks out of the
detritus. Weathering, stream and coast erosion, etc.,
gradually disintegrate the rock substance, which is carried
into the sea, and laid down at the bottom of it as sedi-
mentary beds. These in their turn, after having been
consolidated into sedimentary rocks by the enormous com-
bined pressure of ocean and superimposed strata, emerge
gradually, as we shall see hereafter, above the sea-level,
only to be worn down again in order to form new strata ;
until by constant repetition of this process the whole
structure of the successive geological formations has been

built up.

Before we enter upon this part of our subject we must
point out that the hypothetical stages outlined above are
by no means free from doubt. There are difficulties in
the way of their acceptance, which we can only mention
briefly. If the original earth crust furnished the material
for the successive sedimentary rocks, it should form the
lowest stratum underlying all the other geological forma-
tions. But, as the latest discoveries seem to indicate, the
earliest accessible Archaean rocks do not seem to correspond
well with such an assumption. They are rather igneous
rocks, interposed generally between the stratified rocks

JtllH>

22 THE FIRST PRINCIPLES OF EVOLUTION

and the supposed original crust, which is nowhere accessible.
We should have to assume that after the formation of the
primitive crust a prolonged era of widespread volcanic
action ensued, completely burying the crust under a mass
of poured-out lava. Such eruptive activity on a grand
scale, however, could only take place if a great deal of the
gases and steam, supposed to have been forced out into the
atmosphere by the fiery-hot globe, was retained within it
for a long time, to be given off gradually in volcanic ex-
plosions. Besides, a dense, heavy atmosphere, overcharged
with steam and carbonic acid, and acting, as it were, as
a warm blanket to the earth, is hardly consistent with the
existence of organic hfe-forms, such as are known to have
abounded in the very earliest geological times. At least
their organization does not warrant our postulating funda-
mentally different atmospheric and thermal conditions for
them.

According to the planetesimal theory, which was based
by Chamberlin largely on geological considerations, the
early phases of the earth would read rather differently.
We would have firstly the nuclear stage, at which the globe,
small as yet, is not able to hold an atmosphere, the light
gases, not being attracted sufficiently by gravitation, flying
off into space.* By gradual accretion an atmospheric
envelope was gathered round the globe, partly by accumu-
lation of the surrounding nebular masses, partly by ex-
trusion of the gases occluded in the nucleus itself. The
gases ultimately condensed and led to the appearance of
water, which first accumulated within the lithosphere,
because saturation ensued there most quickly. Gradually
the water oozed out to the surface to form oceans. Violent
extrusion of gas and steam would at the same time bring
about a stage of vulcanism, and therewith lead to the
formation of the oldest geological strata of igneous rocks.

* The atmosphereless stage is thus seen to precede the later
stages, in contradistinction to the usual theory which ascribes the
want of an atmosphere (as, e.g., of the moon) to the absorption of it
m the declining age of the orb.

-■fc'

-^1

GEOLOGICAL EVOLUTION

From thence the further geological stages are the same
according to both cosmic theories.

(6) The Known Geological Stages,
The known geological strata which form the supercrust
of the earth can be arranged into five great divisions, each
being subdivided into systems, etc. (see Table, Fig. 4).

Epoch.

Archean
Proterozoic

Palaeozoic

or
Primary

System.

Mesozoic

or
Secondary

Cenozoic >>

Precam-
brian
Cambrian

Silurian
Devonian

Carboni-
ferous
Permian
Triassic

Jurassic
Cretaceous

Eocene
Oligocene
Miocene 1
Pliocene /
Pleistocene
or Glacial
Post-
glacial

Fauna.

Flora.

Foraminifera ; Crus-
tacea

Sponges ; corals ; crus- Algae
tacea; shellfish

Fish; insects

Land snails ; fresh-
water shells

Amphibians

Reptiles
Marsupials

Flying reptiles
Birds

Placental mammals

Manlike apes
Man

Mosses ;
ferns;
horsetails

-\ iiursei

Gymno-
sperms
(conifers ;
cycads)
Angio-
sperms

II
8

7
Si

Fig. 4. — Table of Geological Periods with Successive
Appearance of Typical Life-Forms.

{Modified from E. Clodd.)

As these beds were superimposed upon each other in course
of time, their position still gives us, on the whole, the order
of their origin, the lowest being the oldest, the uppermost
the newest stratum. Very often, however, the whole series

rmmim

ritfWaiil

WB>IVW«9R^"^^^V«r"

24 THE FIRST PRINCIPLES OF EVOLUTION

has been upturned and disturbed by violent upheavals and
distortions. But whatever may be the actual position of a
given stratum, its place in the earth's history can be deter-
mined by the kind of fossils it contains. William Smith,
about a century ago, was the first to show that each
geological period has its own characteristic organic remains,
by which its chronological position can be ascertained.
Later palseontological researches, based on the theory of
evolution, which assumes an actual succession of pro-
gressive Hfe-forms in time, have borne out his contention to
the full, his method having been greatly improved. Being
here concerned only with a general view of the -earth's
history, we shall merely indicate briefly the course of the

events.

We have already noted that the most ancient geological
formation is the Archaean, which consists chiefly of rocks
of igneous origin, while the later divisions are mainly made
up of sedimentary strata. The Archaean land, most prob-
ably sparsely clothed with primitive vegetation, was
gradually worn down by weathering and the encroaching
sea ; and its vast detritus, accumulating for ages reckoned
to exceed all the other geological periods together, went to
form the sedimentary rocks of the Proterozoic era. The
oldest definite fossils yet found belong to the latter stage,
and, though occurring very sparsely, they are of a rather
advanced type, representing the crusters, thus indicating
that life must have been in existence for a very long time
previously in order to be able to attain to such high
organization. The Archaean and Proterozoic formations are
often classed together under the term of " Precambrian,"
coming as they do before the Cambrian system, the first
which, by its abundance of preserved fossils, allows us more
precise knowledge. The story of all successive stages is the
same — a heaving up of the accumulated sedimentary
deposits, their gradual denudation, and the building up out
of their detritus of the next geological stage.

At the beginning of the Cambrian period we find the

GEOLOGICAL EVOLUTION

distribution of land and sea settled in its main outline very
much as at present : a large, low-lying mass of land
stretching across the northern hemisphere of the globe,
covering, according to some accounts, a great part of what
is now the North Atlantic Ocean. No mouiltains existed as
yet, for these were slowly upHfted during later periods.
The Cambrian Sea abounded in a rich variety of animal life,
from the lowest Protozoa, sponges, etc., up to the crusters
and molluscs, the most prominent class being a kind of
cruster. Only doubtful fossils of plants have been found,
though no doubt many must have existed at that time.

During the next stage, the Silurian system, the sea stood
over a large part of the continents, only once more to with-
draw slowly from the land at the close of the period. The
prominent feature of this stage is the appearance of the
first air-breathing animals, the insects, while its end
witnessed the advent of the earliest type of fishes. Of
plants, algae mainly have been recovered. The climate
during the last two periods must have been, judging from
the wide distribution of the marine fauna, uniformly waim
all over the globe.

The following system, the Devonian, is known in England
chiefly as the age of " Old Red Sandstone." The sea inun-
dated the greater part of Europe, leading there to marine
deposits, while in England vast inland lakes were formed,
where the accumulating sediments were transformed into
rocks, of which red sandstone, so prevalent on the Devon
coast, is the most characteristic. This period yields the
first confident traces of terrestrial fife, the earliest land
animal preserved being the snail. A primeval vegetation
of giant clubmosses, ferns, and horsetails, covered the
country.

The immense development of the carboniferous forests
of the next period is well known. Enormous fern-trees,
huge mosses, and mighty horsetails flourished in the vast
swamps of the Carboniferous age, the remains of which
now furnish the coal-seams all over the world. There were

"ffllHW^Hafflff

26 THE FIRST PRINCIPLES OF EVOLUTION

only few terrestrial animals, of which the most interesting
are the earliest types of amphibians. The luxuriant
vegetation, favoured by a very moist and warm climate,
largely absorbed the excess of carbon dioxide (COg) of the
atmosphere, though, according to Chamberlin, the evidence
of the superabundance of COg during the Carboniferous age
is by no means unequivocal. Whatever carbonic acid was
needed for vegetal growth was, according to him, supplied
from volcanic and cosmic sources. Into this period falls
the first beginning of mountain-formation, for it was then
that the so-called Palaeozoic Alps, remnants of which can
be seen to-day in the Vosges, Black Forest, Harz, and
Sudetes Mountains, began their development. The Ural
Mountains, too, seem to date from the same time. The
main cause of the formation of mountain-chains is generally
considered to be the contraction of the earth due to secular
cooling. The shrinkage of the interior of the globe causes
the crust to crumple into huge folds, which rise over the
continents and sink at the bottom of the sea. For not only
does the great weight of the superimposed sediments,
accumulating for millions of years, tend to crush the
oceanic segments downwards, but it would, according to
Professor Sollas, thrust up the adjoining land by lateral
pressure.

During the Permian period the upHfting of mountains
went on apace. In America the Appalachian mountain-
range arose, while large tracts of land emerged in the
southern hemisphere, which bridged over the sea between
Africa and South America on the one hand, and between
India and Austraha on the other, but have since disappeared
again. The characteristic feature of this time is the general
decrease of temperature, and the first indication of definite
climatic zones and seasons. This has been ascribed to
various causes, partly to the depletion of carbonic acid,
which acts like a thermal blanket, partly to the reduction
of humidity by the restriction of the oceanic area, etc.
One thing is certain, that though traces of glacial action

GEOLOGICAL EVOLUTION

have been found as far back as the Cambrian times, the
Permian period is distinguished by the first authentic Ice-
age, the causes of which we shall discuss later. This period ,
too, saw the rise of the first primitive reptiles.

It is unnecessary for our purpose to follow the whole
series of successive strata by describing the essential
characteristics of each. We shall confine ourselves to the
main facts, which prove of general interest from the
evolutionary point of view. The second great era, following
upon the Palaeozoic era, is the Mesozoic, which is divided
into the Triassic, Jurassic, and Cretaceous systems. During
the first period the sea overspread the greater part of
Europe, which then again had a semi-tropical climate.
The greatest significance is attached to the appearance of
the lowest non-placental mammals, and the first flowering
plants, represented by the conifers and cycads. The
Jurassic age saw the origin of the first forerunners of the
birds, evolving from the flyitig reptiles, which abounded
during the Secondaiy epoch. Mountain-building, too, now
started in full vigour, slowly giving rise during the next
stages to the Rocky Mountains and Andes in America, and
the Pyrenees and Alps in Europe. The third epoch, the
Cretaceous, takes its name from the vast beds of chalk
which were formed out of the shell-remains of lowly minute
organisms swarming in the ocean which covered the whole
of Southern Europe. True birds and the advent of true
flowering plants characterize the life of this geological
series.

The Tertiary era, which is divided by geologists into the
Eocene, Oligocene, Miocene, and Pliocene epochs, is dis-
tinguished by a revival of great volcanic activity, which
had ceased during the past ages. The configuration
of the continents assumed its present shape, the great
mountain-ranges, the Alps and the Himalayas, being finally
reared, while the land which had connected North America
with Europe and South America with Africa and Asia
ultimately disappeared. The climate, temperate during

fr"

•• »

28 THE FIRST PRINCIPLES OF EVOLUTION

the Eocene period, became tropical during the Oligocene,
only to grow cold again, and finally to end in what is knmvn
as the great Ice-age of the Pleistocene penod. The
evolution of the animal species reached its crucial point in
the development of the ape-man [Pithecanthropus erectus),
leading later to the appearance of man himself.

The Quaternary era was ushered in by the great Ice-age,
a time when not only the poles and the high mountain-
summits were covered by mighty ice-fields, but when a
great mantle of ice, extending over 6 to 8 miUion square
miles, and up to 10,000 feet in thickness, reached down
over half North America and North Europe. Signs ot
glaciation have been found as far south as the Thames and
the Danube, and on the top of mountains even m tropical
regions There is sufiicient evidence to show that there
was not one ice invasion only, but that the ice retreated
at intervals, only to advance again. Six separate such
invasions, with interglacial intervals, have been made out
in America and Europe. As to the cause of the glacial
period with its alternate arctic and temperate climates
various explanations have been brought forward. Repeated
elevation and depression of the glaciated regions have been
adduced but such periodical oscillations of great continents
within comparatively brief periods seem to be improbable.
Atmospheric conditions, connected with the depletion of
the carbonic acid of the atmosphere, the interruption of
oceanic currents, etc., are also scarcely able to account for
the periodicity of the glacial phenomena. According to
the astronomical hypothesis of James CroU, the regular
recurrence of glacial periods is due to the variations of the
earth's orbit, which produces at definite long intervals
exceptionaUy short summers and long winters. Though
perhaps the most widely accepted theory, this has by no
means remained uncontro verted, so that at the present
time we are still left in doubt as to the real cause or causes

of the Ice-age.

Finally, the Postglacial or Human period embraces the

GEOLOGICAL EVOLUTION

stages of human development from prehistoric times of
the Stone-age through the Bronze and Iron ages to our
own historical period ; upon which stages, however, we do
not need to enlarge here, as they more properly belong to
archaeology than geology.

In concluding this subject it will perhaps be advisable
to give an indication of the time evolved in the past
periods of geological evolution. The computation arrived
at is founded partly on geological, partly on physico-
astronomical arguments. As to the latter. Lord Kelvin
calculated from the rate of secular cooling of the globe,
based on the known rate of increase of heat towards the
earth's centre, that superficial congelation of the globe
must have taken place between 20 and 40 million years ago ;
while the age of the sun, according to the same authority,
lies between the limits of 100 and 500 million years. Now,
since Darwin postulated for the evolution of species a much
greater length of time, there has long been a serious discrep-
ancy between biological needs and physical calculation.
The geological data themselves are very little reliable. For
though the rate of denudation can be approximately
reckoned out — it would, for instance, take about 7 million
years for the European land-complex to be carried piece-
meal into the sea— yet as the time that elapsed between
the several geological strata is beyond our calculation, no
definite figures can be given which are at all useful. Indeed,
the figures given in the Table, Fig. 4, indicate more the
relative duration of each period than its actual age. Lately
Professor J. Joly estimated the age of the earth by the quan-
tity of salt contained in the ocean. As the sea-water was
originally precipitated on to the earth from the atmosphere,
it contained no salts. These were carried into the sea by
the rivers, which dissolved the saline constituents out of the
rocks they traversed. Professor Joly arrived at a probable
age of our globe of 90 to 100 million years. The deadlock
which existed so long between biologists and geologists on
the one hand, and physicists on the other, as regards

30 THE FIRST PRINCIPLES OF EVOLUTION

geological time, and which at one time threatened to prove
a very serious obstacle to the acceptance of the gradual
evolution of species, has now at last been fortunately solved
in favour of evolution. Since radium, which is one of the
constituents of the earth and most probably of the sun, is
known to be a great Hberator of cosmic energy, producing
it by its own disintegration, as we shall see in the next
section, the source of energy available is now no longer
restricted to the contraction of the cosmic bodies. Accord-
ing to G. H. Darwin, we may safely multiply the time given
by Lord Kelvin by a number between ten or twenty. It
would appear, then, that evolution has at its disposal any
time it may require for the origin of species. It is now
roughly put at about lOO million years, while the date of
the great Ice-age lies anywhere between 60,000 and 300,000,
or more years.

3. Atomic Evolution.

Ever since John Dalton, in 1803, formulated the atomic
theory, the permanence and fixity of the chemical elements
has been an accepted axiom of science. He showed that
the elements combine with each other in certain unalterable
proportions ; and also that, if several compounds are formed
by the same elements, the relative weights of any one
element entering into such combinations are simple
multiples of each other. If, as Dalton assumed, matter
is made up of ultimate atoms which cannot further be
subdivided, then the atoms uniting with each other to form
chemical compounds can only combine in whole numbers.
As each atom of a given chemical element has its own
definite atomic weight, the law of chemical combination, as
enunciated above, follows as a matter of comrse. But while
the fundamental basis of this theory remains unshaken,
facts have gradually accumulated which tend to show that
atoms are by no means the indivisible units they were
originally held to be.

'1"

I 'I

'.'..

ATOMIC EVOLUTION

(a) The Periodic Law,

In determining the relative weights of the atoms, taking
hydrogen as unity = 1, it was found that many of the
elements have atomic weights expressible by whole or
very nearly whole numbers : thus the atomic weight of
carbon is 12, that of nitrogen 14, etc. This suggested to
Prout as early as 1815 the idea that the heavier elements
were nothing but condensations of hydrogen atoms, each
element being made up of a certain number of such atoms —
viz., 12 or 14, etc. — according to the atomic weight of the
element. But more precise work soon revealed the fallacy
of this assumption, as it was definitely ascertained that the
atomic weights of the majority of the elements are certainly
not whole numbers.

Of more value was the discovery of Dobereiner, who
found that certain elements had a very great resemblance
to each other, forming little groups of triads which showed
strongly correlated chemical properties. Such groups are,
e.g., calcium, strontium, barium, or chlorine, bromine,
iodine, etc. The interesting fact is that the atomic weight
of the middle element of any one triad is the mean of the
combined atomic weights of the first and third elements of
the group.

The next important step was taken by John Newlands,
who in 1863 showed that the elements, if arranged in order
of their atomic weight from the lowest to the highest, fall
naturally into a number of series, the elements which occupy
the same place in each series forming a natural group,
and being chemically closely related to each other. This law, )\\ r . , / r
which was independently worked out in full by Mendeeff
and Lothar Meyer, is called the ** Periodic Law." Its great
significance lies in the fact that it shows the properties of
the elements to be in some wise dependent on their atomic
weights. Seeing that each such related group, as it were,
forms a natural family of elements, this curious kinship
seemed best explainable by assuming that the similarity

32 THE FIRST PRINCIPLES OF EVOLUTION

of the related elements was due to an underlying unity in
their composition. What this common factor was, chemistry
was unable to tell. But other sciences gradually opened
out new methods of inquiry, revealing hitherto unknown
phenomena, which have brought this great fundamental
problem of matter much nearer a solution.

(b) The Dissociation of Elements.

New evidence in favour of the view that the eighty-odd
elements known at present are but different aggregations of
one primordial substance, was furnished by the advance of
the study of spectrum analysis. Sir Norman Lockyer, by
his extensive researches on the spectroscopic behaviour of
the elements under the most varying conditions, was able
to carry the theory of the dissociation of the elements one
step further. We have seen in the section on cosmic
evolution that each element, when suitably examined
through a spectroscope, exhibits a characteristic spectrum
of its own, by which it is readily distinguishable from any
other element. It was soon found, however, that the idea
of " one element — one spectrum " was by no means correct,
for " certain elementary substances, when differently
treated, furnish two kinds of spectra of quite a different
character, not having any line or band in common."
Lockyer was able to show by the appHcation of various
degrees of heat that the spectrum of a given element
changes with the intensity of the temperature employed.
Not only this, but, applying the same reasoning to the sun
and the stars, he found corresponding changes in the
spectroscopic appearance of the elements according to the
temperature prevailing in the celestial bodies — tempera-
tures which far exceed any attainable by artificial means,
and which thus provide a natural means for the dissociation
of the elements. As the temperature of the stars can be
determined by the extension of their spectra into the ultra-
violet— the hottest stars having the longest spectrum, the
coldest the shortest — Lockyer was enabled to arrange the

ATOMIC EVOLUTION

stars into a series according to their temperature, and to
compare their respective spectra with each other. As a
result, he discovered that the gaseous stars, which are the
hottest, have the simplest spectrum, showing only th9
lines of hydrogen, helium, and asterium (the latter a gas
unknown as yet on earth). In the next order of stars,
those of medium temperature, the gases (except hydrogen)
begin to die out, while the lines of the metals appear,
characteristic of the high temperature of the electric spark.
As these are totally different from the metallic lines at a
low temperature, the suggestion occurred to connect these
simplified metallic spectra with an elemental state different
from that of the ordinary metals. Lockyer therefore
called these substances '* proto-metals," since they form
the stage before the real metals. For the ordinary metallic
lines appear in the stars of the lowest grade of temperature,
the gases (with the exception of hydrogen once more)
having disappeared. It would seem, then, that with an
increase of temperature a progressive disintegration of the
elements takes place. Or, putting it the other way, as the
stars gradually cool down, there are given the conditions
for the successive births of the chemical elements. The
hottest stars contain only a few gases ; slowly, with a lower-
ing of the temperature, more and more of the known
substances make their appearance. Furthermore, as a
general rule, the lightest elements appear first, then the
proto-metals ; the heaviest and most complex coming latest.
All these facts find their simple explanation in the assump-
tion that the elements, as observed by the chemist, consist
of units which vary in number with the degree of the
complexity of the atom.

There are many other phenomena of spectrum analysis
tending to strengthen this hypothesis, of which we shall
only give a few. Thus it is loiown that the so-called iron-
vapour in the sun is in rapid motion. But the up-rush and
down-rush of the incandescent gas are not registered by all
irpn-Une§ alike ; thereby showing that in the sun " we are

34 THE FIRST PRINCIPLES OF EVOLUTION

not dealing with iron itself, but with primitive forms of
matter contained in iron," which are represented by different
sets of spectroscopic lines. Other corroborative facts in
favour of the dissociation theory are the possibihty of
sorting out the apparently haphazard arrangement of the
multitude of spectroscopic lines into a number of harmon-
ious series, each of which must be assumed to stand for a
different set of vibrating particles of the atom in question :
also the spHtting up of yttria by Sir William Crookes in
1883 into at least five components, each giving a distinct
spectrum of its own.

But it must be admitted that, while there is no doubt of
the facts, scientific opinion has been slow to accept the
interpretation advanced by Lockyer. There are weighty
objections, and the question of the ultimate constitution
of the atom would have had to remain in abeyance once
more, had not a new knowledge arisen — the science of
radio-activity — which put the compound nature of the
so-called elements finally beyond doubt.

Radio-activity is a property of matter which was first
discovered by Henri Becquerel in the element uranium in
1896, whilst he was studying the action of X rays and
phosphorescent bodies. Uranium occurs in the mineral
pitchblende. Monsieur and Madame Curie, experimenting
with the latter, found that it is four times more radio-active
than uranium itself. This led them to the conclusion that
there must be a substance in pitchblende many times more
radio-active than uranium. They succeeded in isolating
two such elements, which were named by them" polonium "
and " radium." Radium was discovered in 1898, and its
discovery has well-nigh revolutionized the fundamental
ideas of science.

What, then, is radio-activity ? It is nothing else than a
disintegration of the atom going on spontaneously before
our very eyes.

ATOMIC EVOLUTION 35

If two poles of an electric current are fused into a sealed
glass bulb from which the air has been exhausted to a very
high degree of vacuum (the Crookes Tube, see Fig. 5), and
an electric discharge is passed through the tube, rays are
given off from the negative pole or cathode. These cathode
rays were studied in detaU by Sir William Crookes, who
declared them to be " radiant matter," or " matter in the
fourth state," thus anticipating in a remarkable degree the
modern theory of matter. These rays were shown to travel
in straight lines, producing vivid phosphorescence wherever

Fig. 5. — Crookes Tube in Action.
+ , Positive pole. - , negative pole.
{From " The New Knowledge," by R, K, Duncan.)

they strike the glass. They are charged with negative
electricity, and are deviated from their path by a strong
magnet. They are capable of penetrating through solid
bodies, and generate the X rays. In fact, the cathode rays
are, as Crookes had already pointed out, particles of matter
projected with great velocity from the negative pole. The
same corpuscles are found in burning gases, in glowing
metals, and in incandescent carbon, which act as conductors
of electricity. Indeed, these corpuscles are identical with
the electrons, which, according to the modern electrical

36^ THE FIRST PRINCIPLES OF EVOLUTION

theory, are the carriers of electricity, and which must be
present wherever electric phenomena take place. These
very same rays are given off by radio-active substances,
the radio-active phenomena being due to the emission of
rays from such substances as radium, uranium, thorium,
actinium, etc. Professor Rutherford demonstrated three
kinds of rays given off from radium, which were called by
him a, j8, and 7 rays.

The P rays have all the characteristics of the corpuscles
just described; in fact, they are nothing but negative
electrons shot out from radio-active substances with a much
higher velocity than the cathode rays, attaining nearly the
speed of light.* They cause phosphorescence in certain
substances, affect a photographic plate in the dark, dis-
charge electrified bodies, penetrate through opaque matter,
etc. The mass of a corpuscle has been determined to be a
thousand times smaller than that of a hydrogen atom,
which is the lightest element existing.

The a rays are also particles of matter ; their speed is
much less than that of the ^ rays, their velocity being only
12,000 miles per second. The weight of an a particle is
four times as much as that of hydrogen— i.^., its atomic
weight is 4. Now, helium, which was discovered by
Lockyer in the sun in 1868, and was found by Ramsay in
1895 on our earth, has the same atomic weight. In fact,
as Ramsay and Soddy showed in 1903, the a rays are swarms
of helium atoms constantly expelled with great velocity
from radium and other radio-active substances. In contra-
distinction to the /^ rays, which are negatively electric, they
carry a positive electric charge. They cause phosphores-
cence, are but feebly penetrating, and are only with difficulty
deviated by a magnet.

The y rays are always associated with the P rays,
and are most probably produced by them. They are

* Velocity of light equals 186,000 miles per second ; speed of
shooting stars, 20 to 40 miles per second ; swiftest rifle-bullet, abou
\ mile per second.

ATOMIC EVOLUTION

identical, according to some authorities, with the X rays.
Little as yet is known about their nature; they are
not corpuscles, but most likely waves set up in the
ether.

Now, the remarkable feature of the production of these
rays hes in the fact that we have here before us an actual
sphtting up of a radium atom into several components.
The disintegration of elements, from being a mere theory,
has become an estabHshed fact of science. Not only
this, but a successive series of changes has been made
out in the radio-active substances, leading step by
step from one element to another, and thus exhibiting
a real transmutation of matter. The dream of the
alchemists, discarded by scientists as a useless chimera, has
become true, though not exactly in the manner they had
anticipated.

If radium bromide is dissolved in water, a gas escapes
which is intensely radio-active, and has been called by
Professor Rutherford the " emanation.*' While the atomic
weight of radium is 226, that of the emanation is 222 ; in
other words, emanation is an atom of radium minus an
atom of hehum. But this emanation in its turn decomposes
spontaneously. It has the property of causing objects
brought into its inmiediate neighbourhood to become radio-
active. This " induced radio-activity " is due to the
deposition of an invisible fihn of radio-active substances.
This " active deposit " of radium is non-gaseous, and
represents the successive steps in the disintegration of the
emanation. For by the repeated emission of rays a series
of new substances is formed, each changing into the next ;
these have been named Radium A, B, C, D, E, and F
respectively. The atomic weight is reduced by 4 with
each emission of a, or helium, particles. Some of the
substances are very fleeting, while Radium F, which has
an atomic weight of 210, has been found to be identical with
the previously discovered element polonium. Finally, by
the emission of a further a particle, the atom of polonium

■fe. <r

■Mi

38 THE FIRST PRINCIPLES OF EVOLUTION

changes into Radium G, which has an atomic weight of
206, and is in all probability identical with the well-known
element lead, though its identity has not yet been finally
settled.

But the question arises : If radium continually transforms
itself in the manner described, how is it that there is any
radium left in the world ? However great the store may
have been in past times, it must, one would think, have
disappeared by constant decay. Now, radium emanation
decays too, but we know that it is continuously reproduced
by radium at exactly the same rate as it decomposes, so that
by means of this " radio-active equihbrium " the amount
of emanation present in radium at any given time is always
constant. If the same holds good for radium, there must
be a parent substance which produces radium as fast as the
latter disappears. This source of radium was discovered
by a train of reasoning which we can only just outline here.
Not all the atoms of a given mass of radium break up
simultaneously,* but only a certain number, which is pro-
portionate to the number present, so that it would take a
certain definite time before the whole mass of radium had
undergone disintegration. Now, it has been found that
half of the total mass of radium disintegrates in 1,300
years, another half of what is left — i.e., a quarter — in the
next 1,300 years, and so on, until practically the whole
mass has disappeared. In the same way the time (T)
for emanation to lose half its radio-activity has been
found to be 3-8 days. As both radium and emanation
change at a given rate, the latter much faster than the
former, there will always exist a certain proportionate
amount of emanation to radium, which is a definite fixed
quantity dependent on the relative rates of change of
the two bodies. Now, radium is always found associated
with uranium in constant proportions, i part of radium

* It must be understood, though, that the disintegration of each
individual atom takes place instantaneously by a sort of small
explosion.

ATOMIC EVOLUTION

to 3 million parts of uranium. This means that if
uranium is the parent of radium, it must change more
slowly than radium, its duration of life being three million
times longer than that of radium. In fact, uranium is
radio-active, as we have already learnt, but very much less
so than radium. It emits a rays and changes into a sub-
stance called " uranium X." The further stages have not
all been elucidated as yet, but we know that the ultimate
result of these changes is the element radimn. The im-

Products.

Atomic
Weight.

T.*

Rays
Emitted.

Uranium

238

about 4,000 million

Uranium X . .
Ionium

234
230

years
22 days

/3,r

Radium
Emanation

226
222

1,300 years
3-8 days

a
a

Radium A"

218

3 minutes

■l| ••

214

21 minutes

28 minutes

o-^f^^y

„ F = Polonium
G=Lead (?)

210

210
206

about 40 years
6' 5 days
4-8 days
143 days

/3
a

Fig. 6. — Uranium, Radium, and their Degradation

Products,

{Modified from A. W. Stetvart.)

mediate parent-form of radium, the last product of the
disintegration of uranium, has been named *' ionium." We
have, then, a complete series of transformations from
uranium through radium and polonium to lead. The
whole series as known is given in the above table (Fig. 6),
with the atomic weights, the time of disintegration, and the
character of the emitted rays.

Similar series can be made out for other radio-active
elements.

♦ T=time taken for each radio-active substance to lose half its
activity.

HWa

40 THE FIRST PRINCIPLES OF EVOLUTION

We have arrived at a most interesting and significant
point of our inquiry. We have seen that some radio-
active elements change very slowly, others more rapidly ;
while some are so transient that they exist only for a few
minutes or, it may be, days. Now, we have found that the
quantity of any given element depends on its rate of decay,
so that those elements that change rapidly have only a very
brief existence, while those which change less quickly, like
radium, accumulate in small quantities compared with
slowly changing elements Hke uranium. There is, then, as in
the organic world, a veritable survival among elements. As
Professor Soddy says: "Probably for every stable atom
many unstable ones are being formed. But only the stable
forms can accumulate in quantity, and become known to us
as ordinary chemical elements." Further, the fact that some
elements are rare, while others are very common, will find
its explanation in the greater stability of the latter, which,
changing excessively slowly, are able to accumulate in great
abundance. Nay more, the latest researches have shown
radio-activity to be a common property of the most various
substances, such as water, sand, clay, etc. Indeed, it has
been assumed that all the elements are radio-active to a
certain degree, the difference in the phenomena lying only
in the rate of disintegration. This is so slow in the most
common elements as to be hardly appreciable by our
ordinary methods of investigation.

The transformation of the atom, then, is an estabHshed
fact of science. The elements are compound bodies, consti-
tuted of units which are expelled with explosive force,
producing by this process of disintegration the phenomena
of radio-activity.

(d) The Electronic Theory of Matter.

Do we know anything about the ultimate constitution of
the atoms ? Here we are on the field of theory, of specula-
tion only. The latest and most widely accepted hypothesis
is that of Sir J. J. Thomson, who posits the electron

)

ATOMIC EVOLUTION

as the unit of matter. According to him, the electrons are
the ultimate elements out of which all atoms are built up,
their different properties being dependent on the number
and arrangement of the electrons within the atom. Each
atom is, according to this view, an agglomeration of negative
electrons (identical, as we have seen, with the ^ rays or
corpuscles), which are perfectly balanced by a surrounding
sphere of positive electrons. Such a collection of negative
electrons, in order to be in stable equihbrium with the

Fig. 7. — Free-Floating Magnets. (After Professor Mayer.)
(From " The New Knowledge," by R. K. Duncan,)

positive sphere surrounding it, must arrange themselves,
as Thomson has shown by mathematical calculation,
into definite groups, according to the number of units
involved.* First a small central group is formed, around
which additional groups are successively built up, corre-
sponding with the increase of units. Fig. 7 represents the
configuration of such groups, according to Professor Mayer,

* The corpuscles are not in a state of rest, but are in constant
motion, describing circulax paths round the centre of the sphere
and forming, as it were, a miniature cosmos.

42 THE FIRST PRINCIPLES OF EVOLUTION

as shown by a working model of freely floating magnets in
stable equilibrium. It must be understood, however, that
the corpuscles, instead of grouping themselves in circles,
form in reality concentric spheres in three dimensions.
Sir J. J. Thomson has worked out the different arrange-
ments for a successive number of corpuscles, of which a few
are given in the following table (Fig. 8) . We see that, start-
ing with five units as a group, the same group recurs with
an additional outer group of ten, when we have fifteen cor-
puscles ; while a third group of fifteen units is added on
reaching thirty corpuscles, and so on, with an additional
number of units. Herein lies the explanation of the periodic
law, with its serial formation. The appearance of the same
primary groups at certain intervals accounts for the

Number of corpuscles :

5 lo 15 20 25 30

Number in successive rings : 5

Fig. 8. — Arrangement of Corpuscles. (After
Sir J. J. Thomson.)

periodical recurrence of similar elements, resemblance in
group formation of corpuscles implying similarity of atomic
constitution and chemical behaviour of the elements.

As to the ultimate nature of the electrons themselves, we
can here only touch Hghtly upon the subject. What the
positive electrons are, has not been determined as yet. They
are only known as attached to the atom, to which they give
a positive electric charge. Thus an a particle is an atom
of helium plus a positive electric charge. The negative
electron or corpuscle has an independent existence of its
own. It has, as previously said, a mass which is equal to
tuVtt o^ that of a hydrogen atom. It consists of a unit of
negative electricity moving rapidly through the ether,
thereby carrying along with itself a certain portion of the
surroimding ether, which is the larger the greater the speed
of the moving electrical unit. The amount of this " bound "

i^yf''^-?^ -'^'{■'•''fPT'' ~ r^'^" " ?y •■"?■

EVOLUTION OF LIFE

ether represents the whole mass of the corpuscle ; the
electrical unit itself (being a vortex or eddy in the ether) is
assumed to have no mass of its own. The ether is not
conceived to be imponderable, as hitherto held, but to
possess a certain mass, its atomic weight being, according
to Mend^eff, nearly one-millionth of that of hydrogen.
We have, then, according to this theory, the new formation
of matter (the atom) out of non-matter (negative electricity)
by the intermediary agency of the ether.

The process of inorganic evolution sketched in the
previous parts is thus seen to be complete, embracing as it
does the first origin of matter, its gradual elaboration into
elements, and the building up out of them of the mighty
bodies which are known to us as nebulae, stars, and planets.

4. Evolution of Life.

The development of living organisms out of inorganic
matter was a common belief amongst the ancients. Spon-
taneous generation [generatio cBquivoca) was held to be a
fact by Aristotle, who taught that animals, such as
worms, insects, and even fishes, could originate from mud.
This idea only gradually gave way in the seventeenth
century to the sounder doctrine of Harvey, the discoverer
of the circulation of the blood, who estabUshed the truth,
so far as the higher animals were concerned, that all living
beings spring from eggs (omne vivum ex ovo). But when,
with the invention of the microscope, the lowest one-celled
organisms were discovered, the theory of abiogenesis (the
origin of the living out of the non-living) once more came
into vogue, and was freely upheld for infusoria, bacteria,
and other micro-organisms. It was only in the last century
that this view was finally proved to be untenable, for
Pasteur and Koch showed that, if proper precautions are
taken to exclude the germs ever present in the air, no
organisms arise except from pre-existing parent forms.
Still, while biogenesis, or the origin of the living from the

H'Wit».^»«yr-

44 THE FIRST PRINCIPLES OF EVOLUTION

living, is thus accepted as the rule for all organisms, there
remains the wider question : Whence the first living beings ?
The answer to this problem depends on the view we take of
life as such in contra-distinction to what is generally called
matter.

{a) Matter and Life,

There is a school of thought which is wont to make a
sharp contrast between the organic and inorganic, and
which has insisted on the existence of an insurpassable gulf
between the phenomena of life and of what is called " dead '*
matter. The VitaHsts of the eighteenth century, as the Neo-
Vitalists of our present time (Sir OUver Lodge, Hans
Driesch, etc.), maintain that, while life is bound up with
matter, there is a special vital principle which, being super-
added to and animating the physical frame, makes hfe
possible. Monism, on the contrary, holds that all cosmic
phenomena, including those of life, are manifestations of
the self-same underlying entity, whatever philosophers may
hold that to be.

Those who uphold a mechanistic theory of hfe (Professor
Verworn and others) claim that there is no fundamental
difference between living and non-living matter. The
distinctions we make for the purpose of convenience do not,
when closely analyzed, hold good in nature. For the sake
of comparison we must take the lowest organized life-
forms which represent the elemental units of all higher
forms. Further, an organism should not be contrasted
with a crystal, as it usually is, but with a substance which
has, like the cell -protoplasm, a semifluid consistency,
being in the colloid state. No absolute difference in struc-
ture can be established between living and lifeless substance,
either in shape, complexity, or organization. A simple
amoeba has no definite shape nor special organs, while its
complexity is only one of degree. The test of genetic
derivation is also not thoroughgoing ; for the lowest
organisms multiply by mere fission, as a drop of oil would
separate. The division between physical and physiological

EVOLUTION OF LIFE

function is not quite distinctive either ; for the resemblance
between an engine fed by fuel giving out power and the
human machine is very close indeed. There remains the
chemical difference. It used to be the main argument of
the vitalists in favour of a special life-force that organic
products could not be built up except by the living body.
Indeed, the term " organic compounds " in chemistry had
reference to the fact that they were believed to be formed
only in and by living organisms. But as early as 1828
Wohler succeeded in producing urea, an organic waste
product, by chemical synthesis, and since then a great
number of organic compounds have been manufactured
artificially ; so that this once so essential distinction of
organic and inorganic substances has been completely
abolished. Furthermore, it has been found that no ele-
ments enter into the composition of organisms which are
not to be found in inorganic nature also. The contrast
between such chemical bodies is only one of degree, the
organic compounds being on the whole far more complex in
constitution. But while thus a natural kinship existsbetween
the inorganic and organic series, there are certain chemical
compounds which are distinctive of the organism, for they
are only to be found associated with the function of life, and
never occur in inorganic nature. These are the proteids,
the carbohydrates, and the fats. The proteids are never
absent in any organism. It would be rash, however, to
base on this fact alone a fundamental distinction between
life and matter, and to call in a new principle of a vital
agency to explain phenomena connected with the action
of proteids, while no such special principle is deemed
necessary to account for the action of the less complex,
inorganic compounds. There are some scientists, however,
who, though not professed vitalists, would demur to some
of these conclusions. According to Professor J. A. Thomson,
the living organism is " a self-stoking, self-repairing, self-
preservative, self-adjusting, self -increasing, self-reproducing
engine," and " it profits by experience," which no machine

lippwjuii.-— '

^f*^j£;3i3jg33gjj3jjgjj22jj;ji3l

46 THE FIRST PRINCIPLES OF EVOLUTION

can do. For the vitalists the process of life, though con-
nected with physical processes, is a phenomenon sui generis
and cannot be explained by mechanical principles.

Now, it may be true that the phenomena of life cannot at
present, and perhaps never will, be satisfactorily explained
in physico-chemical terms, just as little as we can describe
chemical action in terms of radio-activity. Each time we
come upon a higher synthesis of matter we have to take
account of the new factor of recombination. But though a
special vital principle has been claimed by the adherents of
vitalism for the phenomena of life, it has never been clearly
defined or positively demonstrated. As Professor P. C.
Mitchell has put it : " We have to scale the walls, open the
windows, and explore the castle, before crying out that it
is so marvellous that it must contain ghosts."

(b) The Origin of Life.
Applying, then, the foregoing facts to the problem of the
origin of life, we cannot but come to the conclusion that
there must be a unity of development in all nature. Seeing
that there is evolution in the inorganic sphere at the
beginning of the cosmic process, and that there is evolution
of the organic world at the latter end of it, the principle of
the unification of causes would lead us to search for the
origin of Hfe on similar Hues. Indeed, primordial arche-
biosis, or an initial derivation of protoplasm from non-
living particles, by a series of steps, is, as Huxley already
pointed out, an unavoidable postulate of science. A
number of transition stages must be posited, because the
lowest known organisms are highly complex beings, while
the earliest living things must, according to Haeckel, be
assumed to have been nothing but " completely^ homo-
geneous, structureless, formless lumps of proteid." It is
for this reason that all pronouncements as to the artificial
generation of living organisms in the laboratory must be
regarded with the utmost caution, because, so long as
the exact chemical composition of proteid is not even

THE EVOLUTION OF LIFE

known, the production of living protoplasm is not likely to
succeed.

It is at the present stage of our knowledge perhaps little
profitable to attach much value to speculations with regard
to the exact process of the evolution of Hfe. We shall merely
mention the four most prominent hypotheses, remarking
that they serve only as hints of what might have happened.*

It has been suggested by Lord Kelvin and also by
Helmholtz that hfe may have come to our earth from other
cosmic bodies. Though the possibility of such an occur-
rence cannot be totally denied, it only puts off the real
solution of the question. For either life has been in exist-
ence from eternity — i.e., has never been originated — a
supposition we can, after the foregoing, hardly entertain,
or it has been originated somewhere out of something.
And it is just this problem that we have set out to solve.

Professor Preyer rather reverses the problem and
maintains that hfeless matter has been derived from the
living substance, the former having been separated out hke
slack from the originally molten mass of the earth's body.
But on this supposition the intensely hot molten globe,
with its powerful molecular movement, would have to be
looked upon as living, which is an unwarranted extension
of the term " life."

Perhaps the most plausible hypotheses are those advanced
by Haeckel and Pfliiger respectively. According to the
first, life had its origin in the primeval sea. There are
several facts which speak in favour of this supposition.
The earliest known organisms are inhabitants of the water,
of which origin traces are still to be found in the human
species, according to Charles Darwin, in the lunar periodic
function of woman. If we take the elements constitut-

♦ On the vitalistic view of life it would still have to be assumed
that the vital element is related somehow or other to the inorganic
framework. It would lead us too far to enter here into the details of
these theories, which carry us into the field of metaphysics. We
would refer the reader to Professor W. McDougall's book on " Body
and Mind " (191 1).

, ^ ^ •V^ 4,*W-J I.

48 THE FIRST PRINCIPLES OF EVOLUTION

ing sea water and air, we find a curious resemblance to
the composition of proteid, both being made up mainly of
the elements carbon, oxygen, hydrogen, nitrogen, and
sulphur. Strange to say, these are also the first elements
originating in the process of inorganic evolution, being the
elements which appear in the hottest stars. In fact,
Pfliiger's theory would put the origin of life back to the
incandescent stage of our globe. He found in the behaviour
of living proteid the most striking resemblances to cyanogen
compounds (compounds of the cyanogen group, CN), and
concludes that, as cyanogen arises in an incandescent heat,
a synthesis of the constituents of proteid must have taken
place at fire-heat.

It has become clear that life must be looked upon as the
last stage of a series of consecutive changes which go right
back to the origin of the starry worlds. Organic evolution,
which is concerned with the development of life-forms on
our globe, occupies only a relatively very small point in the
line of evolution viewed as a whole. It acquires such an
enormous importance for us, only because man is the final
outcome of this evolutionary process, and this conclusion
vitally affects our whole outlook of life, our moral standards,
and practical endeavours.

•fr

J>.~^

•ipiaMWBWM

SECTION II

ORGANIC EVOLUTION

There still exists a very widespread confusion as to the
exact import of evolution. To the average layman,
Evolution and Darwinism are, as pointed out in the first
chapter, convertible terms. The reasons are perhaps not
far to seek. Up to the appearance of Darwin's " Origin of
Species," the prevaiUng belief was in the immutabiUty of
spec.es, in accordance with the biblical tradition. Though
attempts had previously been made to substitute for the
story of creation a theory of progressive development of
organisms, they failed to gain acceptance. It was only
when Darwin, by his masterly marshalhng of an abundance
of carefully collected facts, showed how the origin of species
could be conceived to have actually taken place by means
of Natural Selection, that the world accepted evolution as
a fact. Indeed, the fight between Evolutionists and Anti-
Evolutionists turned in the beginning exclusively upon the
question whether the transformation of species advocated
by Darwin for all Hving beings, including man, was true or
not. It is Darwin's merit to have established evolution as
an irrefutable fact of science. " There is, however," as
Romanes insisted, " a great distinction to be drawn between
the fact of evolution and the manner of it, or between the
evidence of evolution as having taken place somehow, and
the evidence of the causes which have been concerned in the
process." In other words, the facts of evolution are quite
independent of any theory which may be brought forward
to explain them. " Even if it be fully proved," says

49 7

^ I JtM»itta||IIMllM IlifigaMWWW

. — c*-.,-

;-~M:"'v.pjr'

50 THE FIRST PRINCIPLES OF EVOLUTION

Romanes, *' that the causes which they " (the biologists)
" have hitherto discovered, or suggested, are inadequate
to account for all the facts of organic nature, this would
in no wise logically compel them to vacate their theory of
evolution in favour of the theory of creation." For the sake
of clearness, we are therefore following Romanes' example
by dealing in the first part of this section with the facts
of evolution, and in the second part with the theories of
evolution.

•^

•I,

PART L—THE FACTS OF EVOLUTION

It has just been said that the truth of the evolutionary
principle rests solely on the array of facts which can be
brought forward in its support. There are hosts of such
facts, which find their most ready interpretation in the
hypothesis of the transmutation of species by progressive
evolution, while the only other alternative theory, that of
special creation, offers us no explanation whatever. Now,
the value of any scientific theory depends on its power to
correlate various seemingly disconnected phenomena and
bring them under one harmonious view. The wider the
appUcation of such a working principle, the more assured
we are of its correctness as a law of nature. It is just on
these grounds that evolution has come to be regarded as a
fundamental axiom of human knowledge, while the old-
fashioned creation theory has gradually been abandoned in
every field of scientific inquiry. The statement that the
world has been created as it is once for all by a supernatural
act, is not only contrary to the ascertainable facts — for it
can be proved that all things are subject to progressive
change — ^but the creation theory, as it stands, does not even
attempt to account for such facts ; it simply refers them back
to an inscrutable act of creation. Numberless phenomena
have become known, mainly through new researches stimu-
lated by Darwin's evolution theory, which are only ex-
plainable by the principle of evolution, and we shall in the
following pages give a selection from the truly over-
whelming mass of material, arranged according to the
subject-matter into — (i) Morphology, (2) Embryology,
(3) Classification, (4) Palaeontology, and (5) Geographical
Distribution.

CHAPTER III

MORPHOLOGY

According to the evolution theory, all higher organisms
have descended from the lower by a process of transmuta-
tion. As the surrounding conditions changed, animals and
plants, by adapting themselves to the new environment,
were gradually transformed, and gave rise to new species.
This progressive development of organisms, leading to the
origination of manifold new types from a common ancestor,
substitutes therefore for the fixity of species a constantly
changing flux of the organic world, the different classes of
organisms being linked to each other by a natural kinship,
which is the closer the more recent the divergence from the
original stock. This bond of union is first and foremost
expressed in the morphological traits of the related species.
For as the related animals (or plants) are descended from
the same ancestral type, they must possess on the whole
the same anatomical structure and organization, more
or less modified in each individual case according to the life-
habits of the organism. It is this fundamental identity
of structure that we mean when we speak of the " unity
of type " in a given class of organisms, while the different
parts and organs which are built on the same general
plan in the various species are said to be homologous. In
contradistinction, analogous organs are such as fulfil the
same physiological function without possessing the same
anatomical structure, as, e.g., the wing of a butterfly and
that of a bird, which, though both serving for flight, are
constructed each in a totally different manner.

[

2 ^-

a
z

M
OS

H
b)

(X4

r,-^!

6...

)

54 THE FIRST PRINCIPLES OF EVOLUTION

I. Homologous Structures.

Homologous structures, then, offer the most striking
evidence for the transformation of species, remaining
totally inexplainable on the creation theory. There is
no conceivable reason, on the latter theory, why the
paddle of the whale should be built on exactly the same

Man. Dog. Hog Sheep Horse

Fig. 10. — Anterior Limbs compared.

sc, Shoulder-blade ; 2, bone ot upper arm ; ab, bones of forearm •

5, bones of wrist ; 6, bones of hand ; 7, bones of fingers.

(From "Darwin and after Darxcin" by G. J, Romanes.)

pattern as the forefoot of a quadruped, and why this in its
turn should be identical bone for bone with the arm of a
man. Nor does it offer any explanation why the wings of
the extinct flying reptiles and of the modern birds and bats
should all be arranged according to the same homologous
design— that of a mammalian limb. If we compare the

2^s^

Fig, II. — Wing of Reptile, Mammal, and Bird compared.
(From 'Darwin and after Darwin,"' \y G. J. Romanes.)

56 THE FIRST PRINCIPLES OF EVOLUTION

figures (9, 10, and 11) we see that all these organs, be they
paddle, wing, foot, or arm, consist of the same bones,
variously modified to serve their several purposes. What,
then, is more natural than to assume that there exists a real
relationship between these different structures, each being

transformed and adapted to
its special function, in the
whale for swimming, in the
bird for flying, etc. ? Indeed,
that this is the true explana-
tion will appear at once, if
we remember that all these
animals belong to the same
great class of vertebrata,
whose skeleton is built ac-
cording to a uniform type.
Descent from a common an-
cestor, and progressive de-
velopment on divergent lines,
according to the special needs
of each species, account in
the most natural manner for
these otherwise so strange
and mysterious coincidences.
..^x*.»x .^^^ , .v., ^.. A similar case of trans-
lobe ; pm, maxillary palp; fonnation of the Same parts

mx^, under lip or second • j 1:

maxiUffi with similar de- mto the most vaned appli-
tailed parts. ances is that of the mouth-

organs of insects. Who would
suspect that the jaws of a
beetle, the tongue of a bee, and the long proboscis of a
butterfly, are identical structures ? '^^5^t this is so. All
three are, as can be seen from Figs. 12, 13, and 14, built
out of the same original parts, being modifications of the
mouth-organs of some primitive insects.

Further evidence of the same kind is furnished by what
Darwin has called " serial homologies." Many animals

MORPHOLOGY

Fig. 12. — Mouth - Parts of
Cockroach {Periplaneta
Orientalis). (After R.
Hertwig.)

la, Upper lip ; md, mandibles ;
mx^, first maxillae with c,
cardo ; st, stipes ; li, in-
ternal lobe ; le, external

(From " The Evolution Theory;'
by A. Weismann,)

are divided into a series of segments, each segment being
fitted out originally with identical organs Now such
homologous structures are often transformed in different

.aiL

Fig. 13. — Head of Bee.

Au, Compound eyes; au. ocelli ; «^^fJ?t^^^^ ',/^' ^P?"'^^^^^^

mandibles ; mxK first maxillae, with ^m. rudmentary maxillary
palp ; mxK second maxilla, with internal lobes (/.) f^sed to
form the "tongue"; le, external lobes of second maxillae
(" paraglossae ") ; pi, labial palp.

(From " The Evolution Theory," by A. Weismann,)

parts of the body according to the special needs of the
organism. Thus we find in man the upper and lower limbs,
though serving such different purposes, built on the same
plan (Fig. 15), both being adaptive modifications of the

i (1

:m:

58 THE FIRST PRINCIPLES OF EVOLUTION

typical mammalian limb. In crusters the complex jaws
and legs are plainly homologous, for there is a constant
relation between the number of anterior mouth-parts and
the number of remaining legs. On the creation theory all
these facts remain inexplainable. except perhaps on the
supposition that unity of plan was implied in the purposeful
act of creation. But it would seem that, if intended, such
unity has not been carried out with much consistency ; for
we find homologous structures, though designed for the

OM-

Fig 14.— Head of Butterfly.

A, Seen from in front : au, Eyes ; la, upper lip ; md, rudiments of
mandibles ; pm, rudimentary maxillary palps ; mx , nrst
maxilla modified into suctorial proboscis ; pi, palps of second
maxillffi, cut off at root, remaining in B, which is a side view ,
at. antennae. (Adapted from Savigny.)

{From " The Evolution Theory,** by A. Weismann.)

same purpose, adapted in the most varied ways. We need,
for instance, only compare the forms of wings illustrated m
Fig. II in order to see how differently the object of flight
is achieved in the construction of the wings of the various
vertebrate animals. According to the evolution theory,
this would be only natural, as each species developed on its

own lines.

In plants we find serial homology in the several whorls ot
the flower— sepals, petals, stamens, and pistils— all being

MORPHOLOGY

metamorphosed leaves, of which there is evidence in the
occasional transformation of one into the other.

2. Rudimentary Structures,

We have seen how the forefoot of the whale has been
transformed into a paddle. But the whole body of this
animal has undergone a corresponding adaptation to its

A B

Fig. 15. — Upper and Lower Limb of Man compared.

A, Upper limb ; B, lower limb. The corresponding bones are in-
dicated by the same number.

{From " Darrein and after Darwin" by G. J. Romanes.)

aquatic mode of life by becoming spindle-shaped with a
fish-like tail. This has been achieved by a reduction of the
hind-limbs, of which only rudiments are left, hidden under-
neath the skin. The process can be followed in the seals,
where the limbs are seen to be in an intermediate state,
the dwindling not having gone quite so far (Fig. 16).

6o THE FIRST PRINCIPLES OF EVOLUTION

MORPHOLOGY

>*.^

Rudimentary organs are of very frequent occurrence. The
creation theory is unable to account for them on any
rational basis, while they are most easily explained on the
theory of descent with modification. For, according to
this hypothesis, organs which through changed conditions
of life have become useless, are apt to dwindle away
gradually, because they no longer fulfil any vital function.
In fact, survival of such vestigial structures is the best
indication of the actual change in progress in living

F''ti^^

fi,ifo$fMCfJrA/Ky ///yp-i/Affi5

A. \/er/r.

' Fig. 17. — Rudimentary Hind-Limbs of Python.
{From "Darwin and after Darwin," by G. J. Romanes.)

organisms. Thus, while the long, lithe bodies of the snakes
show in most of the species no trace of limbs, the occurrence
of tiny rudiments of hind-limbs in the python is plain
evidence of their original descent from limbed ancestors,
the reptiles (see Fig. 17).

The process of atrophy can be well observed in the wings
of birds. Darwin has shown that in the domesticated duck,
which flies very little, the wings are reduced relatively to
the legs in comparison with the corresponding limbs of the

anv

Hill

62 THE FIRST PRINCIPLES OF EVOLUTION

wild duck. In the ostrich, which never flies, the wings
are very feebly developed, while in the Apteryx of New
Zealand the wing has practically disappeared.

If any further proof of the morphological traiiBfonna-
tion of species through changed conditions were needed, we
have it in the wingless insects and bUnd cave-animals.
Beetles Uving on oceanic storm-swept islands run great "sk
of being carried out to sea during their flight. We hna.

MORPHOLOGY

Fig. 18.— Apteryx.
(From " Dictionary of Birds,*' by A. Ntwton,)

therefore that a great number of beetles inhabiting Madeira
iSotS islands' are incapable of flight, having lost th.r
wings As in these cases the beetles are mostly related to
Sose of the neighbouring continent, the loss of the wings
can only be interpreted as an adaptive inodifica ion due
to the peculiar circumstances of their mode of hfe The
sL^e applies to the loss of sight in cave-animals which have
£Si shut up for generations in natural caves without the

access of light. Such animals as fishes, crabs, tritons, etc.,
have eyes which are in various stages of atrophy. That
they were not specially created for subterranean hfe, but
have changed since their introduction into the caves, follows
from the fact that they are in all cases closely aUied to the
natural species inhabiting the district.

3. Vestigal Structures in Man.

Darwin has shown in his " Descent of Man " that man
has to be looked upon as in all essentials an animal, being
the last outcome of a long succession of evolutionary stages

of the animal world. Not only is
there a general resemblance be-
tween man and his next of kin, the

ail

Fig. 19.

A Sacrum of Man, with Coccygeal Bones (c) ; B, Outline of

Human Embryo with External Tail (c).

au. Ear ; ru, anterior limb ; //, posterior limb.

(From "Darwin and after Darwin^** by G. /. Romanes ^

anthropoid apes, but numerous links have remained, giving
ample evidence of his animal ancestry. The anatomist
Wiedersheim has enumerated as many as 180 of such
rudimentary structures, which do not serve any useful
purpose in man, and can only be interpreted as vestiges
of his animal descent.

There are many animals, like the horse, which can move
their skin and ears by means of special muscles to ward off

mmmm

pifiiiiMiii itwn

64 THE FIRST PRINCIPLES OF EVOLUTION

flies, etc Rudiments of such muscles are preserved in
human beings, though most people have lost the power of

using them. The tail, which
most lower animals possess,
has disappeared in man, but
a remnant of it can still be
found underneath the skin in
the coccygeal bones, which
form the caudal end of the
sacrum in man. The muscles
belonging to the once movable
tail are still traceable in a
very rudimentary condition.
That these parts are really
vestigial structures, having
dwindled down from their
former larger proportions, finds
corroboration in the fact that
the human embryo at an early
stage of its development still
possesses a conspicuous external tail (Fig. 19). Another
rudiment is the vermiform appendix (Fig. 20), a small bUnd

Plica
Semilunaris

Fig. 20. — Vermiform Appen-
dix (marked x).

{From "Evolution and Animal Life,"
by Jordan and Kellog, published by
Appleton and Co.)

Fig. 21. — Eye of Owl and Man compared.

N, Nictitating membrane,

{From "Darwin and after Darwin" by G, J. Romanes.)

process leading from the large intestine, which, serving an
appropriate function in vegetable-feeding animals, has

MORPHOLOGY

survived as a useless structure in man, and is at times even
a source of danger, because not infrequently it is subject
to severe inflammation through the lodgment in it of fruit-
stones, etc. The semilunar fold to be observed at the inner

Fig. 22. — Young Gorilla. (After Hartman.)
{From " Darwin and after Darwin" by G. J. Romanes.)

side of the human eye is all that is left of the nictitating
membrane of the birds, which serves them as an active
third eyelid (see Fig. 21).

Of other peculiarities of man which point to his close
relationship with the apes, we shall only give three more.
Monkeys leading an arboreal life, swinging from tree to
tree, have inwardly curved feet, with prehensile great toes,

■ » II . «' ■

66 THE FIRST PRINCIPLES OF EVOLUTION j

well adapted for grasping branches. Now, young children
possess very mobile toes, the great toe being frequently
used in the manner of a thumb, and they can often be seen
taking up a similar attitude to that of monkeys, curving
legs and feet inwards (c/. Figs. 22 and 23). The same
reason must be assigned for the fact that the human infant

Fig. 23. — Young Child.
{From ** Darwin and after Darwin" by G, J, Romanes.)

possesses extraordinary grasping power in its hands, being
able to support its whole weight by them (Fig. 24). This
power was a Ufe-saving necessity for the young monkey
in the woods, but is in man merely a useless survival.
Finally we mention as an interesting document of
man's primeval origin a curious feature of the external

Fig. 24. — Infant.

Three weeks old, supporting itself by its hands with strikingly simian

attitude of lower limbs.

{From "Darwin and after Darwin," by G, J, Romanes.)

A B

Fig. 25.

A, Ear of man with projecting point (a) ; B, foetus of an orang.
{From "Darwin and afta Darwin," by G. J. Romanes.)

68 THE FIRST PRINCIPLES OF EVOLUTION

ear, which is very prominent in some persons. The
ears of the lower animals are pointed, and the embryo of
the apes still shows this peculiarity in a marked manner.
Later in the development of the human species, the outer
rim of the ear curves inward upon itself, when the rudiment
of the point can often be distinctly traced as a little pro-
jection of the rim, giving thus plain evidence of man's
animal descent (Fig. 25).

«i

CHAPTER IV

EMBRYOLOGY

We have seen in the previous chapter how morphological
traits common to two or more species form an indication
of their natural affinity. Often, however, parts and organs
are so altered in their adult state, through adaptive modifi-
cations to new surroundings, that this relationship cannot
easily be recognized. A clue to the original condition of
such transformed organs is often found by examining them
in their earlier phases of development. For each organism
passes during its embryonic development through a suc-
cession of changes, which correspond roughly to the various
stages attained during the evolution of the ancestral species.
In other words, as this law, propounded first by Professor
Ernst Haeckel and caUed by him the " biogenetic law," is
generally formulated : " The life-history of the individual
is a condensed resum6 of the Hfe-history of its ancestral
species " ; or more briefly : " The Ontogeny (development
of the individual) is a short recapitulation of the Phylogeny
(development of the race)." This law not only explains
satisfactorily why aU higher organisms, starting from a
single cell, pass during their embryogeny through a suc-
cession of more and more complex forms, but also why the
embryonic condition of an organ often preserves an ancestral
form which is different from that of the adult state.

Before entering, however, into the details of this law, we
must give a short general outline of the process of embryonic

development.

■Mt.:.ii^..M-..JI!^JI!MB.'

■■••■■■■■■IIMilMMI

Fig. 26. — Spermatozoa.

fl, Crayfish ; b, lobster ; c, crab ; d, ascarid ; e, water-flea {Moina) ;
/, man ; g, ray ; h, rat ; i, guinea-pig ; k, beetle (immature stage) ;
/. sponge.

{From " The EvoltUion of Sex," by Geddes and Thomson.)

Fig. 27. — Ovum of Sea-Urchin {Toxopneustes lividus),

(After Wilson.)

zk. Cell-body ; k, nucleus ; n, nucleolus. Below the ovum the
spermatozoon {sp) of the same animal is drawn with the same
magnification.

{From "The Evolution Theory," by A. Weismann.)

f),

EMBRYOLOGY

I. Embryogeny

Every animal and plant starts its existence as a single
cell. This primitive mother-cell, as we shall see presently,
gradually gives rise by repeated divisions to the body of
the organism, which thus is nothing but an orderiy arrange-
ment of living cells. The mother-cell itself in all double-
sexed species is the product of the union of the two sex-
cells, the male and female germs, which in the process of
fertiUzation are brought together to form the new indi-
vidual. The male germ is
^P f / called the " sperm-cell " or

' ^ ' " spermatozoon " (Fig. 26) ;

'^■^^ii^l^^^'f^^i,■-

A B

Fig. 28. — Fertilization.

A, Part of the ovum with spermatozoa {Sp) on surface ; B, one

spermatozoon entering the ovum.

[From " Textbook of Zoology," by Carl Claus.)

the female, the " egg-cell " or " ovum " (Fig. 27). Both are
real cells of microscopic dimensions, with a cell-body, mem-
brane, nucleus, etc. In the process of fertilization one of
the small active spermatozoa penetrates the much larger
mature ovum (Fig 28) ; the contents of the two cells com-
mingle ; the nuclei, which are the bearers of the hereditary
qualities, coalesce ; and the new mother-cell is formed,
which thus comes to unite in itself the characteristics of
both parent organisms.

The next stages of embryonic development are funda-
mentally alike in all multicellular animals. The primitive

72 THE FIRST PRINCIPLES OF EVOLUTION

mother-cell, after a complicated process of division of
its nucleus, splits into two daughter- cells ; these in the
same manner into four granddaughter cells, and so forth,
until a solid ball of cells is formed, in appearance very

Fig. 29. — Embryogeny of Sagitta.

I to 4, Primitive mother-cell with successive divisions ; 5, morula ;
6*blastula, 7 and 8, gastrula ; 9 and 10. coelomula ; e. ectoderm ;
* ' entoderm ; 0, primitive mouth ; a. primitive mouth or gut-
cavity ; V, ccelom folds ; c. coelom cavity, i to 5. Full views ;
6 to 10, sections of embryos.

(From " Natural History of JZreation," by Ernst Haeckel. By kind permission of the
^ A tUhor and Publisher. )

much Hke a mulberry, and therefore called a " morula."
This morula undergoes further changes. Its central cells
liquefy, so that instead of a soHd ball we now get a hollow
sphere, composed of a single layer of cells, and called a

EMBRYOLOGY

- blastula." From this blastula arises the next stage, the
eastrula which consists of an outer layer of ceUs (the
/ i'S^i, an inner layer of ceUs (the entoderm) both
enclosing the primitive mouth cavity (Fig. 29). It is as
Tthrblastuir had been doubled in upon itse f hke a
( hollow india-rubber baU. AU these stages are with regard
to their general plan, identical in aU multicellular animals ,
thev differ in the various classes of animals only m the
precise arrangement of the cells, which depends on the
amount and distribution of the
nutritive substance originally con-
tained within the ovum.

In the further transformation of
the gastrula a division of the primi-
tive mouth cavity takes place by
the growth of two folds (ccelom
folds) which start from the dorsal
side of the embryo, and gradually
elongate, to meet at the ventral
side. By the formation of these
two folds the original mouth cavity
is divided into three parts : the
middle part becomes the gut cavity
of the animal, while the two side
cavities represent the two body
or coelom cavities of the fully de-
veloped organism. We have here- . , u- u
S reached the archetype of all higher animals which
S consists essentially of two long tubes, the outer tube
forming the body covering and the inner tube forming the
^T^avity. Between the gut and the outer covenng lie
the two side cavities, separated from each other nght along
the back and front (Fig. 30). The development of the
ater and final stages of the embryo is essen laUy similar
in process, and consists in further comphcations of this
fundamental scheme by additional foldings, etc.

Fig. 30. — Section of a
Young Sagitta. (After
Hertwig.)

e, Ectoderm or outer
covering of body ; i, en-
toderm or inner lining
of gut ; a, gut-cavity ; c,
coelom or body cavities.

(From " The Evolution of Man,*'
^ by E. Haeckel.)

•«MM

■MM

sia-^i

■If mm

IIIIMII.UWI in II

74 THE FIRST PRINCIPLES OF EVOLUTION

2. The Biogenetic Law.

According to the biogenetic law, the development of
each individual multicellular animal by means of these
successive embryonic stages is due to the fact that the
multicellular animals themselves were originally derived
from single-celled organisms, which, during the course of
evolution through the ages, assumed one by one the

Fig. 31. — Amceba Dividing.

{From " The Evolution Theory" by
Aug. Wdsmann.)

Fig. 32. — Cell Colony of Gonium.

a. View from above ; h, side view.
(From " Textbook of Zoology,'* by Carl Claus.

different body structures described above. As the lowest
organisms became more and more complex by the addi-
tion of new stages, so the offspring, which each time
had to start its own development over again from a
single cell, had to pass through the same successive trans-
formations. According to this theor3^ there ought, there-
fore, to exist a paraDelism between the development of
the individual and the evolutionary stages of its ancestral
species. We find, in fact, that the lowest species of the

EMBRYOLOGY

animal kingdom correspond in a large degree to the
embryonic stages sketched above. We have at the bottom
of the scale one-ceUed animals, Uke the amcebas, infusonans,
etc., consisting of a single cell (Fig. 31). The next step is
exemplified by some of the amoebinas, flagellates, etc.,
which after division do not separate, but cohere together
and form a cell colony (Fig. 32). Further progress is
indicated by the type of animals which, like the Mago-

Fig. 33. — Magosph^ra Planula.

A, Seen from above ; B, transverse section.

(From " The Natural History of Creationr by Ertist Haeckd. By kind permission

of the A uthor and Publisher.)

sphara planula of Haeckel, the Volvocinese, etc., form a
hollow sphere of cells, but so loosely connected that, when
the sphere dissolves after a time, each individual cell can
carry on a separate existence (Fig. 33). The gastraea type
is represented by some of the lower coelenterata, as sponges,
etc., which consist essentially of two layers of cells, with a
primitive mouth cavity (see Fig. 34) J while all the higher
types of animals, however complex in structure, are built
upon the archetypal plan of the coelomula, possessing an
inner gut cavity, two side cavities, and an outer covering

mtt^tm

idMi

■■is!'**"

76 THE FIRST PRINCIPLES OF EVOLUTION

of skin. The adult form of the lowest vertebrate, the
lancelet or Amphioxus, still shows very clearly this
primitive type (Fig. 35) •

A - B

Pig. 34. Trophysema Primordiale. (After Haeckel.)

A External view of the animal attached by its foot to seaweed.
' B longitudinal section, h, Ectoderm (incnisted with grains
of sand) ; g, entoderm (among its cells lie amoeboid egg cells
of large size, e) ; d, gut-cavity with mouth (m).

{From "Darxtnn and after Darwin," by G. J. Romanes.)

So far, we have shown the biogenetic law in its appHca-
tion to the most general features of animal develop-
ment. Representing the lowest, i.e,, earliest stages of
animal evolution, they are common to all animals ; for.

EMBRYOLOGY

as we have said, the embryonic
development each time repeats the
previous ancestral stages. But the
same rule holds goodjfor the later
stages. Thus the highest vertebrata,
including man, pass during their
embryonic development through a
series of transformations which re-
present roughly the evolutionary
stages of the lower vertebrate
ancestry. As the successively
higher forms were evolved by the
addition of new features (some-
times by the loss of old ones), so
the embryonic development was
modified accordingly. Fig. 36 re-
presents three later stages in the
development of some of the verte-
brate animals, from fish upward to
man. We see that in the earliest
of these stages there is hardly any
difference to be found in all the
embryos, while in a somewhat later
stage all the mammals still appear
practically identical. Such resem-
blances can only be explained on
the supposition that there were in

Fig. 35. — Amphioxus Lanceolatus.
(After Haeckel.)

h, skin (ectoderm) ; d, gut {do, dorsal
wall ; du, ventral wall of gut) ; mg.
stomach (anterior part of gut) ; 0,
mouth ; c, body-cavity ; au, eye ;
ch. notochord ; m i, brain-bladder ;
m 2, spinal marrow ; k, gills ; a,
anus.

(From "Darwin and after Darwin" by G. J.
Romanes.)

78 THE FIRST PRINCIPLES OF EVOLUTION

the evolutionary line of man fish-like and lower mam-
malian ancestors.

It is important, however, to guard against a misinterpre-
tation of the biogenetic law. We have said that the
embryo of any given higher species passes through the
various evolutionary phases of its own ancestry ; but this
is not to be understood in the sense that all ancestral forms
are seriatim repeated in fall. Thus, for instance, the human
embryo is not, as popular fancy still has it, at one time a
fish, then a dog, etc. ; but all that can be asserted is that
it possesses at a given period of development certain traits
which are characteristic of the fishes, later those of the
lower mammalian type, and so on. Thus gill arches and
gill slits can be seen in all the embryos of the first series in
Fig. 36 ; but while they are retained by the fishes right
through life, they disappear in all the land animals.* In
other words, we cannot refer each embryonic stage to a
previous ancestral adult form, but must rather look for
a parallelism between organs and sets of organs. A
comparison of the embryonic forms of both related species
rather than that of the adult forms, gives us the clue to
their organic relationship. We must further understand
that the ontogeny is only a condensed and foreshortened
recapitulation of the phylogeny. This is due to the fact
that, as new varieties appear and have to be taken up into
the embryogeny, readjustments become necessary bet^yeen
the various ontogenetic stages. Also, the role a given
organ plays during the embryogeny depends, of course, on
its ultimate state of perfection ; new and important organs
will in the development naturally crowd out dwindling
organs which are in the process of elimination. A selection
of organs, as it were, takes place from among the host of
old transmitted forms, such arrangement prevailing as
will best lead towards the final adult type.

A further factor occurs which tends to distort the simple

* Remnants of the gill slits are sometimes found as an abnor-
mality in adult human beings.

EMBRYOLOGY

[epetition of the ancestral series. New embryonic stages
Lav be interpolated which have nothing to do with an-
fcestral inheritance, but are the expression of new adapta-
tions of the species during the embryonic penod. Haeckel
called " cenogeny '' this process of new formations dunng
embryogeny, distinguishing it from that of the ,rep^^f ^^^
of the old forms, which he called pahngeny For in-
stance, the pupa of a butterfly must be looked upon as a
cenogenetic stage> for the pupa itself could not exist as an
independent organism. The marveUous transformation of a
crawHng caterpillar with biting jaws into a winged butterfly
which lives by sucking nectar from flowers, was evidently
too complex to be achieved without the interpolation of
this pupa stage. Other forms there are, again, where the
embiTonic development is modified cenogeneticaUy in
order to meet certain new requirements of the embryo
itself Thus Fritz MiiUer showed, as early as 1864, that tne
voung forms of the Crustacea, though built according to a
certain prototype, are more or less modified according to
their habits of Hfe ; and Lord Avebury has demonstrated
something similar for the larvae of some insects

We must point out, finally, the important fact that, as
new stages are added to the development of the individual
the old stages are naturally pushed back further and

further in the embryogeny. ,,,,., • - „

We can now see clearly why, as we stated at the beginning
of this chapter, certain affinities can be traced in the
immature stage which are completely lost m the adult.
We shaU conclude with some additional cases. The ex-
ternal tail of man is still discernible in the human em-
bryo (Fig. 19) ; rudimentary teeth are found m the embryo
of the whale, though they never break through the jaw,
and are replaced in the adult animal by whalebone. The
voung of a certain land salamander {Salamander aira),
which breathes by lungs, still possess, before they are bom
complete external giUs. The markings m the young of
some birds are often atavistic, i,e,, revert back to the wild

J I

riiii

m»

-■'WltmKmmmmmmmMmtmimmmmfmr

III ^ 3U

Fig. 36. — Series of Embryos at Three Comparabi

(From "Darwin and aft

TK IK HE

Progressive Stages (marked I, II. III).
in,*' by G. /. Romanes.)

■■"-i '

82 THE FIRST PRINCIPLES OF EVOLUTION

ancestral type of the species ; while the adults have the|
own characteristic plumage, and so on. .

Altogether, the new science of comparative embryologj
has thrown a flood of light on many hitherto unexplamabl^ ,
phenomena, and has contributed in no small degree to tht
solution of the intricate family relationships which exist,
between aU natural species. To this problem we now turn
our attention.

CHAPTER V

CLASSIFICATION

Man in order to gain knowledge of the natural objects
around him, tries to classify them according to their
likeness or unlikeness. Thus, one great distinction is
made throughout Nature, that of inorganic and orgamc ;
while aU organisms are once more separated into two
large kingdoms— animals and plants. In eariy times the
further classification proceeded on very simple methods.
Striking external features were used for distinguishing the
smaller groups of organic beings. Thus, plants were
divided, according to this primitive classification stm
extant in the Bible, into grasses, herbs, and trees ; wlule
animals were distinguished according to their abodes
into air, water, and land animals. The earhest scientific
attempt at classification was made by Aristotle (fourth
century B.C.), who estabhshed for the first time the great
distinction between backboned (vertebrate) and back-
boneless (invertebrate) animals; though he erroneously
held the latter to be bloodless, and named them accordingly.
No further important step was made until Linnaeus, m the
eighteenth century, arranged all animals into six great
classes— mammals, birds, amphibians, fishes, insects, and
worms, which latter class included all the organisms now
recognized as lower than worms.

Slowly, with the advance of scientific knowledge and the
recognition of internal structures as a basis for comparison,
a more detailed classification became possible. The
various groups were better defined and new ones were,
added, as the distinctions, especially between the lower

84 THE FIRST PRINCIPLES OF EVOLUTION

PLANTS.
Division I. Cryptogams (flowerless plants).
Subdivision I. Gymnospores (naked spores).

Class I. Algae.
Class 2. Fungi.
Class 3. Lichens.

Subdivision IL Angiospores (enclosed spores).

Class I. Mosses.
Class 2. Ferns.
Class 3. Horsetails.

Division IL Phanerogams (flowering plants).
Subdivision I. Gymnosperms (naked seeds).

Class I. Cycads.
Class 2. Conifers (pines, etc.).
Subdivision IL Angiosperms (enclosed seeds).
Class I. Monocotyledons (one seed-lobe).

Grasses, sedges, palms, etc.
Class 2. Dicotyledons (two seed-lobes).

Trees, shrubs, etc.

ANIMALS.
Division I. Invertebrates (without backbone).

Class I. Protozoa (one-celled).

Amoebae, infusorians, etc.

Class 2. Coelenterata.

Sponges, corals, polyps, etc.

Class 3. Echinodermata.
Starfish, etc.

Class 4. Worms.
Class 5. Arthropoda.

Crabs, spiders, insects, etc.

Class 6. Molluscs.

Oysters, snails, cuttlefish, etc.

Division IL Vertebrates (with backbone).
Class I. Fishes.
Class 2. Amphibia.

Frogs, etc.

p,G. 37. — Classificatiqn of Pi^ants

CLASSIFICATION

forth immature

ANIMALS— Division II. Vertebrates (with backbone)— continued.

Class 3. Reptiles.

Serpents, lizards, etc.

Class 4. Birds.

Class 5. Mammals (suckling the young).

Family i. Aplacentals (bringing
young).

Order i. Monotremata (one- vented).
Duckbill, ant-eater, etc.

Order 2. Marsupials (pouched).

Kangaroo, opossum, etc.

Family 2. Placentals (bringing forth mature young).

Order i. Edentates.

Sloths, etc.

Order 2. Whales.

Order 3. Ungulates.

Genus i. Suidae (pigs).

Genus 2. Equidae (horses).

Species i. Equus cdballus
(horse).

Species 2. E. asinus (ass).

Species 3. E. zebra (zebra).

Genus 3. Bovidae (cattle, sheep, etc.).

Order 4. Rodents.
Order 5. Carnivora (beasts of prey).
Genus i. Felidae (cats).

Species i. Felts leo (lion).
Species 2. F. tigris (tiger).
Species 3. F. domestica (cat).
Genus 2. Canidae (dogs).

Species i. Cants familiaris

(dog).
Species 2. C. vulpus (fox).
Species 3. C lupus (wolf).
Genus 3. Ursidae (bears).
Order 6. Insect-eaters.
Order 7. Bats.
Order 8. Primates.

Apes and man.

AND Animals (abbreviated).

86 THE FIRST PRINCIPLES OF EVOLUTION

organisms, became more and more accurate. Thus the
present arrangement of classes was reached, each class
being divided and subdivided into smaller and smaller
groups, as families, orders, genera, and, lastly, species,
which are the smallest aggregate units of simdar mdi-
viduals (see Table, Fig. 37. which gives the most impor-
tant divisions and subdivisions of plants and animals).

Such a linear arrangement of the plant and animal
world is, however, as we shall see presently, too narrow
in its conception. It does not express at all the mtncate
cross-relationship which exists between the different
organic types. Cuvier, by his discoveries in palseonto ogy,
and Von Baer, by his studies in comparative embryology,
were led to adopt a new and more correct method of
classification, that of diverging branches from a common
centre. In this way a great tree of mutual affinities was
graduaUy elaborated, which, in its more general ramifi-
cations, is given in Fig. 38. Such an arrangement not only
applies to the great divisions of the animal and plant
kingdoms, but also, as Haeckel has worked out in detail,
to the smaller groups and subgroups.

What does this tree of life, as it has aptly been caUed,
actually signify ? We must clearly understand that all
classification is merely a human device; the divisions
are, as Spencer has said, " subjective conceptions, which
have no absolute demarcations in nature corresponding
to them " This is not only true of the larger divisions, as
is evident from the fact that they have been constantly
modified with the progress of science, but also of the lowest
unit group of individuals— tha species. The species, as
now understood from an evolutionary point of view, is not
a fixed entity, " a thought of the Creator," as Agassiz still
expressed it ; but is, as much as the higher taxonomic
divisions, a human conception, which varies as our know-
ledge increases. There exist, in fact, transitional forms
between species, which thus often shade into each other
This is, indeed, the central idea of the whole theory of

■11

IIIBIII llll 'i"» '""^

^m-

MAN

Biros

, ,r

AILLE8S Apes

Whales. Unciilatcs. Elephants

Composites (Daisy, Oahua)

Olive Convolvulus

(Primtiive) Ungulates

LEO Monkeys

Beasts of Seals

PRtV

(Primitive) Flesh -Fceociis

Roses, Apples

Oaks, Nettles

ooimts.Lemups.Bats.

ISECT-FEEOERS

PLACENTALS InSCCTB CrUSTACKA

Pines, Larches

(^Conlfei

Palm-ferns^

(Cycads)

Palms. Grasses

Ptef^IDOPHYTES Ferns

(Liverworts
Mosses Ccelenterata

Lichens (jelly-'TisK
^ — .^ Coral-builderB)

MOLLUSCA ^

(CuUI«ft*h
Oysters)

ECHINODERMATA

Sea-r'rfra*
Star-fish)

Sponges

Protozoa

Amaebaa
Monera

Protoplasm - plus Chlorophyll

Fig. 38. — Tree of Lifi^

The relative position of each group indicates the evolutionary stage of that group ; the ascent of the higher life forms

from the lower is more lateral than tht lines indicate.

{From '• The Story of Creation," by Edward Clodd.)

iTofaup. 86.

CLASSIFICATION

org/anic evolution, the main object of which is to account
fori the origin of spmes ^^^^^ .^^^ j^g^

TThis grouping of the whole org ^^^^^

divisions related to each other the ^Pj^^^ P^^ ^^1,^
laCge divisions into smaU^' f^^^j^^^^^^,, ^as con-
vf/ere established before the ^* ^^/J^J^unted for only

tree, giving tff Volition then, between organic species
nrtf d:LtTrm c— Fogemtors in radiating
f I Wformingnew centres for further variations.

™:tnc"4 oHs strLgthened by several other con-

U^aUoTwhich flow as natu^trrcra^rgenS ^r^
' f^^i- ♦Viaf modern classification traces a recu gc

SontHrtth. new '« «-ti"?d£;S?»
modlficalion from on. parent '""• "f ' '?t™ ted Lis

rSh the"c relatLship of the various groups of
^dttJod X; we'rememJer that structures of no func-

XntTLoS: atllab,e% that U does not in aU cases
indicate what might have happened in reahty.

88 THE FIRST PRINCIPLES OF EVOLUTION^

tional importance would tend to remain constant und(|r a
change of environment, and thus continue to be identilcal
in a multitude of different types ; while the useful orgAns
which count in the struggle for life are more Hkely to pe
altered and adapted to new conditions, and thus vary nn
the different lines of descent, obscuring thereby the originW
connections between the allied groups. This, too, accounts
for the fact that adaptive modifications are always more o
less superficial, the alteration never affecting the essentials o
the structures involved, so that such organs never lose th
clue of their genetic relationship. It is for the same reason^
too, that an aggregate of small characters is often found]
more valuable for classification than any one important}
single character. The appearance in a number of groups ol
the same unvarying set of characters, however trifling, can
only be referred to an original ancestral source, from which
these insignificant points were derived as a common heritage. \
It has become evident, then, that our classification of\^
plants and animals is based upon an underlying principle —
that of the actual genetic relationship of the organisms —
and not on a mere arbitrary system, as, for instance, the
grouping of the stars. This is finally shown by what have
been called " chains of affinities," which can be traced
among certain groups of organisms. In some cases, as,
e.g', the crustaceans, no common trait has been found which
is characteristic for all the types included ; still, an organic
chain of successive types can be arranged, so that each is
clearly allied to the next, though the extreme forms of
the chain have no resemblance to each other. This can
be explained only on the theory of descent with modifica-
tion. Each type is a slightly altered form of the previous
one, without any great gap appearing between any two
forms. The transmutation of species is here, as it were,
preserved in its successive steps before our very eyes.
Indeed, the tracing of the successive lines of descent during
past periods is our next great argument in favour of evolu-
tion, which we deal with in our next chapter.

CHAPTER VI

PALiEONTOLOGY

We have explained in the previous chapter how the
natural classification of organisms led to the adoption of a
genealogical tree of life, because it best represented the
complex mutual affinities of the related types. We have,
further, shown that the tree arrangement is most easily
accounted for by supposing a real genetic descent between
the different groups. Have we any proofs for such an
assumption ? We shaU be able to demonstrate that the
researches of palaeontology completely vindicate the
evolutionary position.

Before entering, however, into the details of the palae-
ontological evidence, we must not omit to draw attention
to the difficulties connected with " the testimony of the
rocks " It Hes in the nature of fossils that their preserva-
tion depends on a concurrence of favourable circumstances,
and this necessarily causes the geological record to be very
scanty and imperfect ; for, besides the fact that only
certain parts of organisms can become fossilized, such as
teeth, bones, horns, etc., they must remain undisturbed
for long periods, buried away from the influence of weather-
ing and decay. Furthermore, access to the deeply em-
bedded strata is possible only over a very hmited portion
of our globe, and even there only comparatively small
tracts have been explored by the palaeontologist. It is no
wonder, then, that the book of life which we try to read by
means of fossils has come into our hands in an incomplete
condition. But this very fact teaches us not to consider

89 "

88 THE FIRST PRINCIPLES OF EVOLUTION^

tional importance would tend to remain constant unde|r a
change of environment, and thus continue to be identilcal
in a multitude of different types ; while the useful orgAns
which count in the struggle for life are more likely to pe
altered and adapted to new conditions, and thus vary nn
the different lines of descent, obscuring thereby the originW
connections between the allied groups. This, too, accounis
for the fact that adaptive modifications are always more o
less superficial, the alteration never affecting the essentials o
the structures involved, so that such organs never lose th
clue of their genetic relationship. It is for the same reason
too, that an aggregate of small characters is often foun
more valuable for classification than any one important'
single character. The appearance in a number of groups o
the same unvarying set of characters, however trifling, can
only be referred to an original ancestral source, from which
these insignificant points were derived as a common heritage. \
It has become evident, then, that our classification of!
plants and animals is based upon an underlying principle —
that of the actual genetic relationship of the organisms —
and not on a mere arbitrary system, as, for instance, the
grouping of the stars. This is finally shown by what have
been called " chains of affinities," which can be traced
among certain groups of organisms. In some cases, as,
e.g., the crustaceans, no common trait has been found which
is characteristic for aU the types included ; still, an organic
chain of successive types can be arranged, so that each is
clearly allied to the next, though the extreme forms of
the chain have no resemblance to each other. This can
be explained only on the theory of descent with modifica-
tion. Each type is a slightly altered form of the previous
one, without any great gap appearing between any two
forms. The transmutation of species is here, as it were,
preserved in its successive steps before our very eyes.
Indeed, the tracing of the successive lines of descent during
past periods is our next great argument in favour of evolu-
tion, which we deal with in our next chapter.

/ CHAPTER VI

' PALiEONTOLOGY

We have explained in the previous chapter how the
natural classification of organisms led to the adoption of a
genealogical tree of life, because it best represented the
complex mutual affinities of the related types. We have,
turther, shown that the tree arrangement is most easily
r.ccounted for by supposing a real genetic descent between
the different groups. Have we any proofs for such an
assmnption ? We shall be able to demonstrate that the
researches of palaeontology completely vindicate the
evolutionary position.

Before entering, however, into the details of the palae-
ontological evidence, we must not omit to draw attention
to the difficulties connected with " the testimony of the
rocks." It lies in the nature of fossils that their preserva-
tion depends on a concurrence of favourable circumstances,
and this necessarily causes the geological record to be very
scanty and imperfect ; for, besides the fact that only
certain parts of organisms can become fossilized, such as
teeth, bones, horns, etc., they must remain undistiu-bed
for long periods, buried away from the influence of weather-
ing and decay. Furthermore, access to the deeply em-
bedded strata is possible only over a very limited portion
of our globe, and even there only comparatively small
tracts have been explored by the palaeontologist. It is no
wonder, then, that the book of life which we try to read by
means of fossils has come into our hands in an incomplete
condition. But this very fact teaches us not to consider

89 12

90 THE FIRST PRINCIPLES OF EVOLUTION

the absence of a leaf here and there as evidence that no juch
record was ever written ; while, on the other hand, if we
read our history correctly in the light of evolution, we must
find no proof which goes positively against the evolutionary
principle. And this is how the case actually stands.

If evolution has occurred in the plant and animal world,
we must find a uniform progression from simple to higher
and more complex beings. Starting from the most primi-
tive organisms, there must have taken place a constarit
divergence and re-divergence of life-forms in many direv':-
tions, leading not only to an increase in the number df
types, but also to a greater specialization. Studying
Fig. 38, which gives the genealogical descent of plants and
animals in its main outline, we see at once that there is'
as we ascend the tree, not only a greater diversity of
organisms, but also a general elevation of type ; while it
will be evident at a glance from Table 4, that there
is a fairly complete parallelism between the age of the
geological stratum and the level of organization of living
beings first appearing at each epoch. We find the lowest
organisms in the oldest geological period, while each suc-
cessive stage shows a progressive ascent of plant and
animal life. Thus, plants passed from the simplest algse
through the spore-bearing ferns, etc., on to the flowering
species ; the gymnosperms (firs, pines, etc.) appearing
before the angiosperms, which represent the great majority
of our flower-bearing plants. The animal series developed
through the whole line of invertebrate ancestry, reaching,
by way of the lower vertebral stages, the non-placental
marsupials, and ultimately, through the mammals, man
himself, the acme of the animal species, of whom the first
definite traces are found during the latest geological period.

The geological evidence in favour of the evolution of
species throughout past ages is corroborated by many
other facts. Thus, it is apparent that, if new species arise
only in connection with pre-existing forms by a gradual
process of development, an old extinct type can never re-

PAL^ONTOLOGY

^.¥

appear, as would be quite conceivable on the old theory of
creation ; for there is no reason why types should not be
created over and over again ; while, on the contrary, ac-
cording to the evolution theory, the formation of any given
species can only be reached by an elaborate process of
modification which runs through a long series of genetically
interrelated types, and can therefore never repeat itself.
It is for the same reason that old species differ from the
later ones, being more generalized in form, and that the
divergence in t>pe corresponds to the amount of time that
has elapsed between the appearance of the respective types.
The transmutation of forms is a slow process, and, except
in those cases where organisms have survived unchanged,
the modification is greater, on the whole, the longer the
time that has passed. As the types are constantly diverg-
ing, spreading out, as it were, wider and wider from the
original centre, it follows that the old forms will differ less
among themselves than the new forms.

The outstanding proof, however, of the palaeontological
evidence lies in the fact that there is a real succession of
types in accordance with geological stratification. There
is not only a close correspondence between the fossil forms
in consecutive geological formations, but "a wonderful
relationship in the same continent between the dead and
the living." The most typical example is, perhaps, that
of Australia, which has no endogenous mammals above the
non-placental Marsupials and Monotremata (kangaroo,
etc.). These find their counterpart in the extinct forms
of the tertiary deposits in the same continent, which also
are all of the lowest mammalian type, and are related to
the now living forms. Similarly, the characteristic sloths,
ant-eaters, and armadillos of South America are closely
related to the extinct Megatheriums and Glyptodons of
the same region ; and so on.

If there was a progressive development of the organic
world in past ages, as the evolution theory assumes, there
ought to be no great break between any two successive

92 THE FIRST PRINCIPLES OF EVOLUTION

Ufe-forms. Seeing that the gaps are stiU considerable in
the grouping of existing types, the question arises : How
far has palaeontology been able to supply the " missing
links "7 In connection with this question we must not

Fig ,q —Slab containing Remains of Arch^opteryx. From

THE Original in the British Museum ; reduced.

{From the article "Birds;' in the Ninth Edition of '* Encyclopadia Brttonnica.")

forget the fact, previously mentioned, that the mere absence
of positive evidence does not mihtate against the accept-
ance of the theory of descent with modification ; while,
on the other hand, favourable testimony, however scanty.

PALEONTOLOGY

is of the utmost value. Furthermore, it is erroneous to
expect that any two divergent types can be directly con-
nected by intermediate forms. This depends entirely on
the actual line of descent, whether one type has originated
directly from the other or not. Thus, e.g., it is popularly

Fig. 39A. — ARCHiEOPTERYX Macura ; restored. About One-
Sixth Natural Size. (After Flower.)

{From "Darwin and after Darwin;* by G. J. Romanes.)

believed that man has sprung from the now-existing apes.
This is not correct. We should express their relationship
much better by calhng them " cousins," both having de-
scended from a common progenitor. It follows, therefore,
that no direct hnk between man and present-day anthropoid

94 THE FIRST PRINCIPLES OF EVOLUTION

apes can be found ; we must rather look for a common
unknown ancestral type, combining the generalized features
of both, towards which they converge. It is in this way
that old forms often connect younger, now widely separated

groups.

In this sense a great many missing links have been un-
earthed with the progress of palaeontological discoveries.
The most striking example is, perhaps, that of the Archae-
opteryx (Fig. 39A), which represents the transition stage
between reptiles and birds, being in general appearance like
a bird, with wings and feathers, etc., though it still has
teeth in both jaws, a long vertebrated tail like a lizard, and
three well-developed digits on the wings.

A beautiful series of intermediate forms has been made
out in the evolution of the horse. From a five-toed proto-
type it slowly changed through a number of stages, gradu-
ally losing most of its digits, remnants of which can still
be traced in the splint-like bones at the side of the one
remaining large digit, which now forms the hoof of the
modern horse (Fig. 40). Such a reduction of toes has
taken place more or less in all hoofed animals. The earliest
land animals, moving slowly over marshy tracts, had their
full contingent of digits, which were used fully extended
on the ground. Gradual adaptation to rough and hard
surfaces raised the foot from the ground and evolved the
strong and swift type of hoofed animals, as the camel,
deer, etc. Intermediate stages can be seen in the pachy-
derms, the three-toed rhinoceros, the four-toed hippo-
potamus, and the five- toed elephant.

A great many other such continuous series of fossils
can be made out in similar ways, all witnessing to the truth
of the evolutionary principle. We shall only mention the
case of the Paludina shells of the tertiary beds of Slavonia,
which can be arranged into a nearly complete group of
forms, one leading by minute steps to the other (Fig. 41) ;
further, the development of the antlers in deer, which
become more and more ramified as we ascend in the geo-

PALAEONTOLOGY

Equus : QuJi-
ternary and
Recent.

PUohippus :
Pliocene.

Protohippus :
Lower Plio-
cene.

Miohippus :
Miocene.

Mcsohippus :
Lower Mio-
cene.

Orohippus
Eocene.

■>1

Fig 40 -EVOLUTION of Horse. (After Marsh.)
^ (From •■ Darmn and after Darwin," by G. J. Romanes.)

Tsap"

"""••im

'^mmgm'

96 THE FIRST PRINCIPLES OF EVOLUTION

logical formations from the Miocene to our own period.
We finally give the extremely interesting case of the evolu-
tion of the tail in fishes and birds, both having progressed
on similar lines. The oldest fishes had a long vertebrated,
tapering, diphycercal tail, running right through the fin to

Fig. 41. — Successive Forms of Paludina Shells.
{From "Darwin and after Darwin," by G. J. Romanes.)

its very point, and giving off rays symmetrically on both
sides. The next in development was the heterocercal fish-
tail, still long and jointed, but built asymmetrically,
broader on one side than the other ; while the latest fishes
possess a homocercal tail which is not vertebrated, but

',1

PALiEONTOLOGY

Fig 42 —Development of the Fish-Tail.
{From " Darwin and after Darwin^ by G. J. Romanes,)

98 THE FIRST PRINCIPLES OF EVOLUTION

spreads out from the enlarged bony end in a symmetrical
fin (Fig. 42). This order of stages is still repeated in the
embryonic development of the most recent fishes, as would
be expected according to the biogenetic law. The develop-

Development of the Bird's Tail.

A, Tail of Archaopteryx with simple joints ; B, tail of modern bird
with foreshortened and consolidated joints.

{From " Darwin and after Darwin" by G, /. Romanes,)

ment of the bird's tail has passed through similar stages,
the long vertebrated tail of the reptile-birds having
changed into the consoHdated typical tail of the modern
bird (Fig. 43).

I u

CHAPTER VII

GEOGRAPHICAL DISTRIBUTION

As palaeontology deals with the distribution of organisms
in time, so geographical distribution gives us the arrange-
ment of floras and faunas in space. Many facts of the
present-day disposal of plants and animals over the world
can only be accounted for on the supposition of an original
derivation of all related forms from common ancestors,
with their ultimate dispersal over the now inhabited areas.
We shall see that the arguments from geographical dis-
tribution fall well into line with the other evidences
hitherto adduced in favour of the theory of descent with
modification.

To begin with, we must point out that neither " pre-
determined adaptation " nor climatic conditions offer a
sufficient explanation of the geographical distribution of
the organic world. On the former theory, we should expect
a complete correlation between the habitat and the kind
of organisms created for it. Now, though, of course,
no species could survive, except in an environment favour-
able to its existence, we do not find the same organisms
in all situations which could support them ; as instance
the rabbit, which, since its introduction into Australia,
thrives so well there that it has become a pest. On
the other hand, if climatic conditions determine the dis-
tribution of organic forms, kindred organisms ought to
inhabit similar regions ; while diverse climates should have
sharply contrasted floras and faunas. But this is by no
means invariably the case. Thus, to give an example

100 THE FIRST PRINCIPLES OF EVOLUTION

quoted by Darwin : " No two marine faunas are more dis-
tinct, with hardly a fish, sheU, or crab in common, than
those of the eastern and western shores of South and
Central America ; yet these great faunas are separated only
by the narrow but impassable Isthmus of Panama. Con-
trariwise, according to the same authority. *' we may
compare the productions of South America south of
latitude 35° with those of north 25°, which are exposed
to considerably different conditions; yet they are m-
comparably more closely related to each other than they
are to the products of Australia or Africa under nearly the
same climates/' Seeing, then, that " like orgamsms are
not universally, or even generally, found m hke habitats,
nor very unUke organisms in very unUke habitats, we
must reject both the above-mentioned hypotheses as in-
sufficient, and look for a further principle of geographical
distribution. This we have, as already indicated, in the
theory of descent with modifications. Assuming that
each species is originally derived from a common central
source, its general distribution over the world can be
accounted for by its dispersal from the onginal habitat
by migration, the routes of migration being determined by

natural barriers.

That such barriers play a decisive role in the mapping

out of the organic areas is evidenced by the following

facts. We find that, wherever a barrier is interposed

between two regions, effectively checking transmigration

of the organic forms from either side, there is to be noted a

difference between the life-forms thus separated, the

extent of this demarcation corresponding on the whole

to the degree of separation. It depends, of course, on the

organism what kind of barrier will constitute a hindrance

to its dispersal. Terrestrial animals will be effectively

separated by great stretches of water, marine organisms

by the interposition of land. High mountains, deserts, etc.,

often act as a sufficient check on both kinds of organisms ;

while in the case of fresh-water inhabitants sea-water may

GEOGRAPHICAL DISTRIBUTION

lOI

serve the same purpose. It is thus, for instance, to be
explained, according to Darwin, that the New and Old ^
Worlds differ so greatly in their terrestrial products, except
in the Northern parts, where free migration was possible
along the land connection which exists between the two
continents. Thus, also, is explained a similar circum-
stance, mentioned by Darwin, that three distinct marine
faunas extend from north to south, occupying respectively
the eastern and western sides of South America and the
eastern islands of the Pacific ; while westward from these
islands, where there are no impassable barriers— islands
and halting-places extending right to the shores of Africa-
no such demarcations in the marine fauna are to be found.
On the other hand, as Darwin once more has so beautifully
shown by experiment, many such seemingly insurmount-
able barriers may be successfully overcome by organisms
under appropriate conditions. Seeds may be transported
by sea-currents for hundreds of miles without losing the
power of germination ; they may be carried still farther
within the crops of birds, in the earth adhering to their
claws, on floating timber, etc. Birds and insects may
travel long distances over land and sea, or may be carried
away in gales, etc. In this way, as we shall see later,
many facts of island life which are otherwise unexplainable
can be most readily accounted for.

We must refer, then, similarity of geographical groups
to community of descent with dispersal by migration.
This becomes apparent on a mere survey of the distribution
of floras and faunas ; for we find that allied organisms are
generally kept together in well-defined areas, " biological
regions " being occupied by species, less frequently by
genera, which are related to each other. Thus, humming-
birds are confined to America, marsupials mainly to
Austraha ; while of the rats and mice, the species restricted
to the New World are distinct from those of the Old World.
The argument from " special design of creation " which
may be advanced here, comes at once to nought when

I02 THE FIRST PRINCIPLES OF EVOLUTION

higher taxonomic divisions are in question. For, while
smaller groups may be restricted to certain areas, no such
geographical Hmitation can be made out for the larger
divisions of plants and animals. This becomes clear on our
theory, when we consider that, as the number of organisms
in any given class increases, the possibility of migration
is accordingly multiplied. Thus, all the species of humming-
birds may be confined to America ; but it would have been
a strange fact indeed if all the birds had thus been limited
to one continent.

This correlation between "areas of distribution and
affinities of classification" not only applies to living
organisms, but also extends to the extinct species, thus
greatly strengthening the proof that community of descent
is the true factor involved. For, as we have seen in the
previous chapter, existing species must be looked upon as
the modified descendants of bygone organic forms. As
A. R. Wallace has expressed it : " Every species has come
into existence coincident both in space and time with a
pre-existing and closely allied species."

The breaking up of biological regions into distinct,
separate areas may come about in several ways. Thus,
we have an Arctic area round the North Pole, which has a
typical flora and fauna of its own. But on going south-
wards, scattered mountain regions are to be found, as the
Alps and Pyienees in Europe and the White Mountains
in America, which in their snow-capped altitudes harbour
plants and animal species of the characteristic Arctic type.
These now-isolated districts were once, during the Glacial
period, continuous with the Arctic Circle, when the whole
of the northern parts of Europe and America were covered
with snow, and supported Arctic life-forms. As the ice
gradually receded towards the Pole, the arctic plants and
animals withdrew on to the ice-bound higher mountain-
peaks, thus becoming cut off from the main parent stock,
and forming isolated patches of Arctic life in the midst of
a now temperate biological region. Darwin accounts in

GEOGRAPHICAL DISTRIBUTION

103

a similar way for the now separated though aUi^l pro-
ductions of the subarctic and temperate P^rts of Jhe New
and Old Worlds. According to him, dunng the later
ptSe period, when a mild J-^te rdgned .^^^^^^
Arctic regions, the main popidation of the Arctic C^le was
.;imilar in tvpe to both continents. With the advent 01

hToLcLl^riod a general -?-tion took^ljace^^^^^^^
wards thus separating the ongmal common stock oi
TrSsms into two distinct biological divisions which are
^STsSy separated from each other by the impassable
srce of ?he whole Atiantic Ocean. Another factor in the
oSnrtion of new geographical units is given - the change

of lea-level, which sometimes disconnects islands from the

mJlnl of which they originally fo'-^ijV"*^^^^
part Thus, the British Isles were separated from the
Kopean continent in relatively recent geological times
anT^ can trace a comparative change m their flora and
flunr comprising a definite, though small, number of
Sant and Smal fpecies, which are pecuUar to th^ islands.
^ In f act-^and this is the last link in the chain of our argu-
ment-segregation of organic forms leads in tme to pro-
gressive mo<Ufication of the orgamsms involved. Though,
£Te have seen, the Alpine flora is Arctic in gf era! char-
acter, it possesses some pecuhar species of its own-the
mSfied£cendantsoftheoriginalArcticstock. Similar^,
the inhabitants of the Arctic Circle as already mentioned
broke up with their dispersal and fS^^\^^'\,f%^°
distinct types-those of the New and Old Worlds The e
is therefore, taking place a progressive modification m
ilatS groups ; and not only this, but there exists a com-
pete SSlation between the extent of the separation and
the amomit of change. This is best exempbfied m the
phenomena of island Ufe, which in themselves ofier a mos^
thorough-going substantiation of the pnnciples of geo-
graphi^ distribution, as detaUed at length above.

We find, in the first instance, that there is no co^dation
between the cUmate of a given oceanic island and its m-

•mfmmmmmmmtf^m

^P"Pi

104 THE FIRST PRINCIPLES OF EVOLUTION

habitants. Thus, " there is," according to Darwin, " a
considerable degree of resemblance in the volcanic nature
of the soil, in the climate, height, and size of the islands,
between the Galapagos and Cape Verde Archipelagos;
but what an entire and absolute difference in their in-
habitants! The inhabitants of the Cape Verde Islands
are related to those of Africa, like those of the Galapagos
to America." Secondly, we notice a strict accordance to
the rule above enunciated that effective geographical
barriers lead to the evolution of endemic types in the
isolated regions, and this in proportion to the extent of
the separation maintained. Thus we find, taking oceanic
islands Hke the Sandwich and the Galapagos Islands, St.
Helena, etc., that they have a profusion of pecuUar types,
though, compared with continental areas, they are, on the
whole, poor in the total number of species. The amount of
modification in any one island corresponds to the lapse of
time since its separation from the mainland. We have ,
seen that the British Isles, which formed part of the conti-
nent until relatively recent times, have comparatively
few peculiar species ; while the most typical oceanic islands,
divided from the adjoining mainland for long geological
periods, possess the greatest number of endemic forms.
Thirdly, the stocking of the islands depends entirely on the
possibiHties of immigration, which in their turn are deter-
mined by the barriers which shut the islands off from the
neighbouring regions. Thus there is an entire absence of
batrachians (frogs, toads, etc.) on oceanic islands, while
practically no terrestrial mammals are to be found on any
one island situated more than 300 miles from a continent .
or great continental island. Bats, however, which can
pass the water barrier by flight, are common in most
islands. This principle applies even to details of geo-
graphical distribution. For instance, in the Galapagos
Islands twenty-one land birds are peculiar out of a total
of twenty-six ; while of eleven marine birds only two are
peculiar. Marine birds evidently find their way to the

GEOGRAPHICAL DISTRIBUTION io5

island more easUy than land birds. Madeira and Bermuda
on the other hand, which are constantly -^-"^f^f^ ^^J
new stock from the ad pining mainland, have practicaUy
no pecvUar land birds. The same fact exp^ns ourfourth
point-namely, that in every case the island fonns are
Sated to thL of the nearest neighbouring continent^
rjo^ From there the original stock has come and ^oj
there is the supply kept up by occasional more or less
frequent transiS't!^ Finally, this factor of ^mmigra ion
S2 explains the phenomenon of subsequent modification

Ts^ls in iso Jed islands, as already. f,«!f°"^S°S
An island, once having been stocked with its on^nal set

o'ufe-for^is. will have most of itV'il'^^^^^Thero'e com"
course of time by progressive evolution. The more com
SeTe the Sationifl, the less chance of interminghng
Sth fresh arrivals of the old typ^the more complete
S be the transmutation of species. Thus is exp -^^^^^^
the above-mentioned fact that oceanic islands show such a
Seat nmnber of peculiar species. Altogether, the evidence
of g™phical Sstribution is seen to be in complete har-
mony with the theory of descent with modification.

PART II.^THE THEORIES OF EVOLUTION

The last five chapters, dealing with the various '* facts of
evolution," have brought before us a multitude of phe-
nomena, of which each series proved itself so much inde-
pendent evidence in favour of the theory of progressive
development in nature. We pointed out at the beginning
of this section that the proofs which establish the general
truth of the process of organic evolution do not in any way
affect our decision as to what may prove to constitute the
particular underlying cause or causes of this process. The
fact of evolution is to be kept quite distinct from the
method of evolution. As to the latter, we must remark
that, if all things evolve, it is only natural to expect that
there exists an " evolution of the evolution theory.'* The
theory propounded by Charles Darwin, and known as
" Darwinism," was by no means the first proposed — ^though
it was the first to gain general acceptance, thereby estab-
lishing the truth of evolution itself as an independent fact —
nor can it in any sense be said to be the last word on evolu-
tion. Though we build on Darwinism, we have gone
beyond Darwin. Evolution theories can be divided into
four main kinds, according to their intrinsic principles :

1. Those which adopt the environmental conditions as
the prime factor of evolution — as the theory advanced by
Lamarck, known as " Lamarckism."

2. The theory of Natural Selection by Charles Darwin,
supplemented by the theory of Sexuaf Selection. Both,
representing Darwin's original contribution to the theory
of evolution, we here call " Darwinism."

3. The theory of Mutation, or Heterogenesis, advocated
by De Vries, which is a modification of the theory of
natural selection.

4. The theories of Orthogenesis, which assume pre-
determined directive lines of evolution.

But before entering into the detailed discussion of these
various theories, we shall give a short account of the
history of the idea of evolution, as it led up to the great
epoch-making work of Charles Darwin, from which dates
the whole new science of evolutional biology.

106

CHAPTER VIII

THE THEORIES OF EVOLUTION
£. HISTORICAL

The first roots of the evolution idea can be traced back,
as we have already said, to the Greeks, whose wntmgs
contained many germs of the most modern views of
nature. Though we must guard against the error of read-
ing too much into their theories, which were mostly philo-
sophical speculations without scientific basis, it must be
admitted that their conception of the universe was much
more in accordance with what has been found to be the
true interpretation of natural phenomena than the bibUcal
view which superseded it for centuries. To the Greek
mind the cosmos presented itself essentially as a world m
motion. Continuous becoming was the keynote of their
systems, whether the primary substance out of which the
world constantly reconstituted itself was held to be water,
air, fire, or any other single entity or combination of
elementary entities (Thales, 600 B.C. ; Heraclitus, 500 B.C. ;
and others) . They anticipated not only the atomic theory
of matter (Democritus, 460 B.C.), but also adumbrated the
modern theory of progressive development, as was done
eg by Anaximander (570 B.C.), who first asserted the
principle of the origin of the living from the non-Uving,
adopted later by Aristotle (350 B.C.). Even the idea of
the survival of the well-adapted forms was foreshadowed
by Empedocles (450 B.C.) and accepted by Epicurus
(300 B.C.). The Roman thinker and poet Lucretius
(50 B c ), who built his system of philosophy on Greek
models, represents fairly weU in his work all that was best

107

,„S THE FIRST PRINCIPLES OF EVOLUTION

i„ Greek philo»phy. «J,'^„,:':^*°t befcve^tte

the whole aspect of human speculation. The autnomy
me wuwc 1^ f-„„„„:e was held to be irrefutable — nay,
*^r>:irThlSst Trelch to be made in the biblical
mviolable. The fi'\* '^'r'" . ^f geological remains,
tradition was due to the study ^J g « ^^^^

Fossils, which ^'^^'^'''^J°t\e"l^^t.oi%i^tnrer
Middle Ages, ^"^.-^f^^f danced £ of their time
^loSoT^^ctiX: «^^^^^^^ -r^. tce'Sunl
organisms. rSut religious pi cj^va Tr^r^n «^n late

was rt Ih a storm of obloquy for P-urnxng to propound
a geological theory contrary to biblical revelation. As to^he
orlanic world, the creation story reigned supreme The
♦li nf Noah's Ark was considered to be hterally true.
Etn° St:, ^he famous systematizerof^ plants^ a^^^^
animals stm declared in the eighteenth century . mere
:""s many different species as dHf erent forms were created
in the bednning by the Infinite Being.
■°;S'S„. 'o, Ihe pickers 0. .J^^tSng'SX'

formation of species in his classic " Philosophic Zoolog^que
iS which must be looked upon as the "lost import^"
SntrLtion towards the science of evolution before

HISTORICAL

109

) I •■

Darwin. But he was before his time. His work did not
gain the attention of the scientists which its importance
deserved. He died in obscurity. So Httle did he succeed
at the time in his purpose, that, when in 1830 a heated
discussion took place in the French Academy between
Geoffroy St. Hilaire, the friend and colleague of Lamarck,
and Cuvier, the latter, who upheld the unchangeableness
of species, gained a decisive triumph for the catastrophic
theory, thus postponing the ultimate victory of the evolu-
tionary view by thirty years.

In Germany, the famous poet Goethe, who was at the
same time a not unimportant scientist, foreshadowed in
a remarkable degree the modern idea of progressive trans-
formation. His views on the " Metamorphosis of Plants "
(published 1790), positing a primitive archetype (the leaf)
of which the other parts of the plant are modifications ;
and, further, his vertebral theory of the skull, embody
distinctly the principle of progressive transmutation.
Lorenz Oken (1776-1851) and Treviranus (1776-1837),
too, must be mentioned as forerunners of the developmental

idea.

In England the foremost name in connection with the
evolution theory in the eighteenth century was Darwin's
grandfather, Dr. Erasmus Darwin, who, in his " Zoonomia "
(1794) anticipated to a large extent the views of Laniarck.

A great impetus was given once more to the evolutionary
hypothesis by the progress of geology. For though
Hutton had failed to overthrow the diluvian theory, which
was the accepted creed of the time. Sir Charles Lyell, the
founder of modern geology, succeeded some decades later.
His " Principles of Geology " (first edition 1830), by sub^
stituting for the cataclysmic revolutions of the old school
the explanation of a natural gradual transformation of the
earth, not only paved the way for the acceptance of the
evolution theory propounded by Charles Darwin, but the
book itself greatly stimulated the author of the " Origin
of Species," according to his own testimony, and thus had

no THE FIRST PRINCIPLES OF EVOLUTION

a direct share in the formulation of the theory of natural
selection. The idea of evolution was evidently m the air.
Darwin himself mentions various writers who before hini
had expressed the beUef in the gradual transformation of
species. We have already mentioned in the introductory
chapter what a large share in the origination and worlong-
out of the developmental hypothesis was due to Herbert
Spencer. His earliest book, "Social Statics" (1850),
several articles between the years 1852 and 1857* but chief
of aU his " Principles of Psychology," published in 1855,
aU present the evolutionary point of view. Of his great
later works, comprising the " Synthetic Philosophy," which
deals with the evolution problem in a philosophical manner,
extending its scope over the whole reahn of natural phe-
nomena, we have spoken previously.

But the outstanding figure in the history of evolution
is Charles Darwin. While on his voyage as naturaUst on
the Beagle, he was drawn by his observations on the fauna
of South America to the consideration of the question of
the origin of species. As early as 1838, after reading
Malthus's book " On Population," he conceived the idea
of the struggle for existence and the selection of favourable
variations among plants and animals as the true cause of
their progressive development. But only after assiduous
labour, extending over more than twenty years, did he
pubHsh his great work " The Origin of Species " (1859).
which put evolution in the rank of a recognized branch of
knowledge. Not only did he bring forward an over-
whehning mass of evidence in favour of evolution, but he
also offered for the first time a satisfactory explanation
thereof. Alfred Russell Wallace, who was exploring the
Malay Archipelago about this time, had been led to adopt
independently the same idea of the survival of the fittest.
In 1858 he sent a short paper on the subject to Darwin, to
be read before the Linnaean Society. It is common know-
ledge how Darwin, on the advice of his friends, was induced
to have a short abstract of his own theory read at the

LAMARCKISM

III

,\"

sa„.e time as Wallace's paper and bow bo^ joint-authors

of the theory -^ r'TitSXZrT^t^t^^^-^-^-S
in appreciation of each °5^^ .^^^.^'irior ^aimof Darwin.

he evolution theory, which were >^«;^^J^?,"ehy^Xa
cL"Satio„ ol this problem »e »« tun. our attenfon.

2. LAMARCKISM

Lamarck was the first to elaborate a theory of organic
evoSon which is still upheld. Though neglected at the
tim'o'torappearance. the principles laid down by him
SeScomeanLeptedcreedwithmanymodern scientists

S look u^n the Lamarckian factors as the true cause of
Tpro^essive development of organisms. Lamarck had
f thoSh grasp of the problem of organic evolution as
VeZ^^hy his repeated publications on t^s ques^:i^.
ranging from the years 1801 to 1815, ^P!«^y '^..J^J
" Philosophic Zoologique," and the preface to his Systeme
de! aSux sans Vertebres." He distinctly pointed out
that theVe are no divisions in the organic world correspond-
ng to the classes, orders, genera, etc.. which -econstoct.
To him even the species was, contrary to the then gener-
Syhdd opinion, not a fixed entity, but merely V a coUec-
S of individuals, being aUke. or almost «>• w^ich rep^-
duction perpetuates in the same condition as long as the
conditions d their situation do not change enough to make

112

FIRST PRINCIPLES OF EVOLUTION

LAMARCKISM

113

their habits, their character, and their form vary." . . .*
" Species merge one into another ; where we see isolated
species, it is only because there are wanting other species
which are more nearly related, and which have not y^t
been collected." According to him, nature has " produced
the difEerent living beings by proceeding from the most
simple to the most complex." ..." One is forced to
recognize," he says, " that the totality of existing animals
constitutes a series of groups forming a true chain." This
series, however, is not a single one, but is " branching and
irregularly graduated."

How, then, have all these varying organic forms been
produced from each other ? " Time and favourable con-
ditions are the two principal means which Nature has
employed in giving existence to all her productions." As
to time, he had very clear views on the succession of
geological periods. For him " time has no hmit." As
to the circumstances, " the principal ones arise from the
influence of climate ; from those of different temperatures
of the atmosphere, and from all the environing media;
from that of the diversity of different localities and their
situation ; from that of habit, the ordinary movements,
the most frequent actions ; finally, from that of means of
preservation, of mode of living, of defence, of reproduction,
etc. Moreover, owing to these diverse influences, the
faculties increase and become stronger by use, become
differentiated by the new habits preserved for long ages,
and, insensibly, the organization, the consistence — ^in a
word, the nature and condition of parts, as also of the
organs— participate in the results of all these influences,
become preserved, and are propagated by generation"
(heredity). In other words, the change of organisms is
due, according to Lamarck, directly to the change of
environmental conditions. As the latter are constantly
altering with time, the organisms undergo continual

♦ All quotations of Lamarck's writings are from A. S. Packard's
book on ** Lamarck "

T^ ■ th« direct action of the surrounding
modification. It is tlie direct acno ^^^^^^

n^ilieu whicli induces new ;'^^'f ^'^'^^ ^^^^tion Lamarck

and thus leads to ^^^g^^^^ aS oHhe '»ii'^''. -<='='>^'i-
distinguishes two modes of this act^on^^^ ^^ ^^^.^^

ing as the organisms m q^^^f^^^" *; ^^ i^^er animals,
The former, to which belong t^e Jf ^ an^^ j^^ ^^^^
do not respond to the enviromnental shm,^ ^.^^ ^

manner as the ^f^^^.^^^^f'^^^t "xp^rience internal
nervous system.- and are ^^e to e ^ ^^^^^^

emotions, which provoke ^^^^J^^IrS to the power
or internal causes, and whicn g>X5 actions." With

which enables them to P«rf°™/^S ^e „"* able to
plants and the lower amn.aU' ^^^^J^^^^ f,,,es is
feel, the interaction with the ^n^u'Vuds of the organ-
mechanical. A new "^°^~ ;3'Vi ,^ttt^Smulated.t "
ism is produced towards the parts dif <="y ^ experiencing

is otherwise with the ^^^^^^^^^^^^^SgZ wants'
a change <^\^^^^^l^^X^:Z^ feeling, forthwith
" Each want felt, exciting ^neir towards the

sets the fluids in motion, ^"^ .forces them to
point of the body where an action may satisfy tne

experienced." modified in accordance

Thus either existing organs f^ ^^'^^^^'^^ted. As to
with the new need, or new ones "?y ^f ^"f^^^^f ^^ organ
the former, observation Fo;«y^"*,*J," ^ an improve-
increases its Power, Jeading^t^^^^^^^^ ^ ^^.^^ ^^P^^ ^^
ment of the organ itself ' ™ wanx

lessened function and ^^^^f ^i^^r arms of a
We need only mention the fjrong mu ^^

blacksmith, or the w«Uf e7^°P,"'i^S^^^ of the limbs
contrast them with th«J^^*S^oSThm sufficiently,
of those who are not ^n thehabi f using th ^^^

especially in the case of P-^^y^- ^,^.13 tobew..out
. Lamarck erroneously supposed the low^ ^g^^^s his argument.

a nervous system. Thjs, however ^n° v^ ^^^ ^ ^^^

t This is substantially correct, thougn we

fjt in the same manner as Lamarck did.

114 THE FIRST PRINCIPLES OF EVOLUTION

that is to say, the nature and form of the parts of the

body of an animal— which have given rise to its habits and
its special faculties ; but it is, on the contrary, its habits,
its manner of life, which have, with time, brought about
the form of its body, the number and condition of its
organs; finally, the faculties which it enjoys." And,
concludes Lamarck, all such effects are transmitted to the
succeeding generations by heredity. Lamarck himself
gives many instances in illustration of this principle. He
thus accounts for the webbed feet of aquatic birds. The
effort to keep afloat induced the birds to spread their toes
asunder as much as possible. This led to a stretching of
the membranes between the digits, which thus became
gradually extended. In the same way the long legs of the
waders, the clawed feet of birds perching on trees, etc.,
are accounted for. Want of use, on the other hand, brought
about the disappearance of the limbs in snakes, the peculiar
immobile fingers of the sloth, and so on.

In order to show how new organs could originate by the
same process, Lamarck gives the example of a mollusc,
which we shall quote once more in his own words : " I
conceive that a gasteropod mollusc, which, as it crawls
along, finds the need of feeling the bodies in front of it,
makes efforts to touch these bodies with some of the fore-
most parts of itself, and sends to these every time supplies
of nervous fluids, as well as other fluids. I conceive, I
say, that it must result from this reiterated afflux towards
the'points in question that the nerves which abut at these
points will, by slow degree, be extended. Now, as in the
same circumstances other fluids of the animal flow also to
the same places, and especially nourishing fluids, it must
follow that two or more tentacles will appear and develop
insensibly under these circumstances on the points referred
to." We see, then, that, according to Lamarckism, the
evolution of species must be attributed to the influence
of the environmental conditions on the organism. These
nitiate new variations of the species, which are fixed

1 \
^ \

LAMARCKISM

in succeeding generations by heredity. A distinction is
to be made between the direct action of the physical factors
by which plants and the lower animals are modified, and
the more indirect process of the effects of use and disuse,
which brings about the progressive development of the
higher animals, including man.

Lamarck tried to substantiate his theory by many lUus-
trations, a few of which we have already quoted. He
explained, by means of the environmental factor, not only
the various kind of birds, but also the form of the flat
fishes with their asymmetrical head and eyes, the long
body of the serpents, the horns and hoofs of the quadrupeds,
the wings of flying mammals, etc. But the main evidence
of the Lamarckian factors has been furnished by the new
school of Lamarckism, the Neo-Lamarckians of whom
we must mention Henslow, Hyatt, Packard, Osborn, Cope,
and Herbert Spencer.

Professor Henslow has accumulated in his two books,
" The Origin of Plant-Structures," and. " The Origin of
Floral Structures," a vast mass of facts about plant life,
all tending to show that the structures of plants are due to
the influence of external agencies. Thus the structure of
the stem, the origin of spines, the shape of the leaves, the
tendrils and pads of climbing plants, etc., can, according
to him, all be accounted for by the reaction of the growing
plant-organism to the incidence of surrounding forces.
It is a well-known fact that plants change their character
with their environment, according as they are reared in
dry or moist climates, in high or low altitudes, etc. Flowers
can similariy be explained by " self-adaptation to insect-
agency." The nectar-seeking insects alighting on the
flower produce various stresses and strains in the floral
parts, whence result not only the different irregularities in
the shape of the floral organs, of petals, sepals, etc., but also
the secretive and hairy processes, the colour-markings, etc.,
of certain flowers. Even the nectaries themselves are,
according to this theory, to be ascribed to the nutritive

ii6 THE FIRST PRINCIPLES OF EVOLUTION

currents in the plant tissues, set up in direct response to
the irritation of the feeding insects.

Coming from the realm of botany to that of zoology, we
have the work of Professor Hyatt, who attributes the
characteristics of molluscs and shells, as well as those of
extant sponges, to the nature of the surrounding media.
A. S. Packard upholds the Lamarckian factors as the
sufficient cause of the metamorphosis of insects, of the
peculiar tubercles, spines, and bristles of certain cater-
pillars, of the climatic variations of butterflies, etc. With
regard to the higher animals, we have the studies of
H. F. Osborn, who explains the structures of mammalian
feet and teeth by the mechanical action of external agencies ;
while Professor Cope sees in "friction, impaction and
strain, brought about by use or motion," the originating
factors of the vertebral skeleton.

It was Herbert Spencer in whom Lamarckism found its
staunchest advocate. Though he took natural selection
to be an integral part of the theory of evolution, he held ,
its application to be restricted to the lower, passive
organisms. The development of the higher animals, in-
cluding man, he considered to be due to the inherited effects
of use and disuse. He made this principle of use-inheri-
tance the central idea in his interpretation of the phases
of organic evolution, basing upon it the gradual develop-
ment, not only of the sense-organs, the nerves and brain-
structures, but also of their concomitant functions. Thus,
e.g., the eye was originated, according to this view, by the
persistent impact of light on a sensitive cell, which, being
modified and developed with progress of time, attained its
present perfection . The genesis of nerves is to be attributed
to the repeated passage of molecular disturbances along
the same paths within a specially unstable medium, etc.
Morality, too, Herbert Spencer treats from the same point
of view. The Lamarckian factors of use and disuse resulting
in a cumulative heritage of acquired habits, are, according
to him, the true cause of the evolution of all ethical feelings.

DARWINISM

117

3. DARWINISM

We have seen in the historical part of this chapter that
to Charles Darwin belongs the honour of having established
organic evolution once for all as a fact of science. But
while the theory of descent, i.e.. of the origin of all species
from earlier forms, is now an accepted commonplace,
thanks to the labour of Darwin and his compeers, this is
by no means the case with the special hypothesis advanced
by Darwin to explain the origin of species. This he did
by the well-known theory of natural selection, to which he
later added the theory of sexual selection. These are
the two ideas which entirely belong to Darwin, and may
therefore be fitly combined under the term " Darwimsm
It is plain, then, that Darwinism is not synonymous with
evolution, nor with organic evolution, of which it is merely
one of many offered explanations.* In dealing with it we
shall first discuss the theory of natural selection and then
that of sexual selection.

A. Natural Selection.

The idea of natural selection was based by Darwin, as
he himself has recorded in his " Autobiography,'' on the
analogy of the method of the breeder and horticulturist
in the cultivation of domesticated vaneties. For ex-
ample, it is known that all the fancy breeds of pigeons, the
carrier, pouter, fantail, etc., are derived in the last instance
from the slate-coloured wild rock-pigeon (Fig. 44)- , I^
order to obtain a particular kind of bird, the fancier picks
out those of his flock which exhibit the desired charac-

♦ Even learned writers have added to the confusion surrounding
the term " Darwinism." A. R. Wallace, the joint-author of the
theory of natural selection, has named his great book on evolution
'• Darwinism." though he expounds therein views ^hich differ in
many essential points from those held by Darwin. We shall come
to these later.

Fig. 44. — Pigeons.

{From "pofwin and after Darwin^ by G. /. Romanes,)

. >>?.-, „ .1 v., t , . I. ,- . i- i.,-i' ■■wgwwfuWpFB'

"•nrnmm^mn^tmm

120

THE FIRST PRINCIPLES OF EVOLUTION

teristics to the greatest degree, and breeds from them.
By constantly weeding out those birds which are not up
to the mark, and propagating from the remainder, genera-
tion after generation, types of pigeons have been evolved
which differ from the original plain rock-pigeon in nearly
every feature. The same applies to the breeding of horses,
dogs, cattle, etc., and to the cultivation of flowers, vege-
table produce, and so on. In every instance improvement
of the stock is obtained by " artificial selection " of the
desired types and the rejection of the undesirable ones.
Now, what is thus to a limited extent achieved by man's
efforts for his own purposes nature effects on a grand scale
throughout the whole range of creation.

But here the determining factor is the struggle for life,
which is present everywhere in nature. Darwin was led
to this fruitful conception by reading Malt bus's book " On
Population." Malthus tried to show that the population,
which increases in geometrical ratio, is always tending to
outstrip the natural increase of the food-supply. This'
applies, so Darwin reasoned, in equal measure to organisms
in a condition of nature. Far more individuals are born
than can possibly survive. Thus the elephant is con-
sidered to be the slowest-breeding animal ; yet the progeny
of a single pair would multiply within 740 to 750 years to
nearly 19 million individuals, if each elephant survived
for propagation. A single annual plant, according to
Linnaeus, would increase to a million in twenty years
if each seedhng produced only two seeds yearly. But the
fertility of plants and animals is in most cases very much
g eater. A single herring is estimated to produce 40,000
eggs yearly, the carp 200,000, and the sturgeon as many
as 2,000,000. The fertility of the lower organisms is
appalling. The output of a single tapeworm is most
probably not less than 100 million eggs, while the prodi-
gality of plants is notorious. The world would soon be
overrun by any one species were there not a check to its
unlimited propagation. This check is furnished in nature

'i:^

DARWINISM

121

bv the stniegle for existence. We know that, generaUy
SeaMne the balance of species remains fair y constant
St ff^m periodical fluctuations-that is. the number
S^liduals is kept within the normal range except ^^
those cases where a species is dying o'^* «' ^^^'^f
raoidlv at the cost of another. This imphes that out of
Se totd nlber of descendants the greater part must

^'now. this destruction of the excessive indivW^J^^ is
broueht about by the struggle for existence, wluch is
So dt First of aU, there is the struggle against adverse
nS conditions, the inclemency of the dimate, the mi-
";Sveness of ' the soil, the advent o^cfaj^^-^
such as floods, storms, etc. ; secondly, there is the ^tUc
with other species in the same habitat, either the direct
S with enemies or the still severer competition for
food ^th allied species, which, being similar in habits,
retue't the same ^ound. These two factors lead n^^-
saiSv to the decimation of the species as it is but cannot
brth^selves alter its character. This is done by the
Srd dement in the battle for life. We have found that
out of the total progeny of a given set o ^'^'J^^du^^' °"ly
a certain number can survive. In meeting the difficiJties
of their existence, the question now anses : Which of the
individuals of a given species shaU succeed, which succumb ?
rZe goes on, in other words, a struggle for existence

within the species itself. , , . ^t i-i

For though the offspring are on the whole in the hkeness
of their parents, it is common knowledge that thisidentity
is not complete. There exist what have been called varia-
tions among any given set of individuals descend^ from
the same stock. The breeder, for example, could not
decnU there were given to him in the fi-t instance
difierent quaUties in his material to seect from. He
cannot create new characters, but can only pick out for
further improvement those provided by nature. That
SS var^abUity exists also in the natural state h« now

122 THE FIRST PRINCIPLES OF EVOLUTION

been amply proved by exact measurements of organisms.*
In fact, there are no two individuals which could not be
found to vary in some one feature.

Now, the struggle for existence has a different effect on
each of the individual members of a species, according to
its natural endowments. It is evident that those in-
dividuals that are well adapted to their surroundings,
having some advantage or other over their fellow-creatures,
will succeed in the struggle of life and leave progeny ;
while those less fitted to their environment are weeded out
entirely. In other words, a natural selection takes place
from among them, leading, as Herbert Spencer has ex-
pressed it, to the " survival of the fittest." Just as in
artificial' selection the breeder selects the desirable types
for propagation, rejecting the undesirable ones, so nature
is conceived as doing the work of natural selection. We
must, however, beware of seeing in this phrase more
than a metaphor. Nature does not select consciously, nor
with a set purpose — that is, teleologically. All we can say
is, that a given set of external conditions acts a^ the
selective agent, determining which of a given number of
individuals is going to survive. It is the better adapted
types which oust those less adapted. The offspring of the
selected surviving members of a species inherit, on the
average, the advantageous parental qualities, and vary
now round the higher level of their parents. As the new
generation is once more subjected to the same selective
process, advancing a further step, a gradual and progressive
modification of the species takes place, generation after
generation, leading to a wonderful adaptation of animals
and plants in all their parts and functions to their surround-
ing conditions. But now, not only do the environmental
factors vary constantly, but the very modification of a
species introduces a new element of change in the economy
of the competing organisms, altering the equilibrium of all

♦ See A. R. Wallace's " Darwinism/' and especially Bateson's
" Material for the Study of Variation."

DARWINISM

T23

(

the other species in relation to their exte'"^^"^^^^^^
Thus a contmuous W^-t^^^^^^^^^ How

going on, producing an infi'"*^ " Vw^^n the various or-
Lse the inter-relation can J'^ ^^^^^^^J^^^^^ The

ganisms. Darwin has ^»\«7,^" ^^J^fXloverT^n/^
Im heartsease (^-'«/'[;;':^ ^^^^^^
pratense) are fertihzed almost exclusively y

^ Hence we may infer as highly probab e y^^^^ -^
genus of humble-bees became ^xtaf J^j/^ome wry
England, the heartsease and '^J <=l°^™''^f humble-bees

i" Md.mic., wUch destroy If" ""^ ^^^5.^ rf

number of cats ; and Colonel Newm W« '^^ humWe-bees
and small ^o^-^^^^^^J^^-f, which attrSe to the

firs? ofmlce,"nd then of bees, the frequency of certain

^To'i^elntlSation of the working of Darwin's
pnncipTe of natural selection, we shaU take the same case

water there were some witn ine wcus u ri+x^^

better developed than others. Now, these being best fitted
to survive would hand down their quaUty to their offspring.

124 THE FIRST PRINCIPLES OF EVOLUTION

from whom once more those with the largest webs would
be selected, and so on generation after generation, until
a fully-developed web would ultimately be evolved by
natural selection. Similarly in the case of the snail : it
was not, according to Darwinism, the effort of the snail
which caused the horns to grow, but snails with slight in-
dications of horns had the advantage over those without
such rudimentary organs ; each tim3 the snails with the
best-developed horns would be selected for propagation,
until the final length of the snails' horns was attained.

It must be clearly understood that natural selection
works primarily for the interest of the species ; it is not at
all concerned with the life of the individual. For it is the
species which is preserved by the selection of the fittest
members, the unfit individuals being rigorously weeded
out for the benefit of the race.

Further, it will have become clear that natural selection
works only on useful variations. It can have no effect
on indiif erent qualities, while harmful characteristics come
under its control only in a negative way, being ehminated
by the selective process. Natural selection is therefore
first and foremost a theory of adaptations, explaining how
these have come about, and are being constantly improved
upon. The origin of species is, as a matter of fact, nothing
but a particular case of adaptation, as applied to the fornaa-
tion of species. But the process holds good for all adaptive
modifications, whether they concern the morphological dis-
tinctions between varieties, species, genera, or any higher
taxonomic order of our classificatory system. Adapta-
tions, then, in general, furnish the evidence in favour of
natural selection. To these we now turn our attention.

ADAPTATIONS.

There are hosts of facts which were seen for the first
time in their true significance by the light of Darwin's
theory of natural selection. Others there are which were

DARWINISM

125

only discovered after a principle was found whereby to
correlate the various phenomena of plant and animal life.
Throughout the whole organic world more and more evi-
dences have been accumulating in favour of the new theory,
so that we have now material at our disposal which is truly
overwhelming, not only in the extent of its range, but also
as regards the details in every branch of study. We can
here give only a small selection from each group of facts.

{a) Plant Structures,

In plants we find a great number of adaptive modifica-
tions which, being of special service to the species possessing
them, can easily be explained by the theory of natural
selection. To these belong, for instance, all the protective
structures which ward off the attacks of herbivorous
animals. There are, first of all, the thorns and spines of
many plants, developed in the most diverse ways, either
growing out directly from the branches or being modifica-
tions of leaves, etc. They are usually so arranged as to
protect the exposed parts of the plant, covering in tall species
only the lower portions. We need only remind the reader
of the wild rose, the holly, thistle, etc. Other plants, as
the stinging nettle, are furnished with irritating, stinging
hairs. Herbs like the deadly nightshade, henbane, etc.,
contain strong poisons ; they are thus made unpalatable,
and are therefore avoided by animals. Clover has a small
amount of tannic acid in its leaves, which acts as an effec-
tive check against the attacks of snails ; while in other
species, as the sorrels, oxalic acid serves the same purpose.
All such contrivances, leading directly to the preservation
of the species, must be looked upon as having been evolved
by the process of natural selection.

But Darwin has shown that a great many other phe-
nomena of plant life — ^in most cases newly discovered by
himself — can be accounted for on the same theory. Thus
in climbing plants their various organs, as tendrils, pads,
etc., are due to an inherent organic quality, being developed

■ija ■■

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126 THE FIRST PRINCIPLES OF EVOLUTION

by natural selection and not by the direct action of external
agencies. Similarly, the beautiful arrangements of in-
sectivorous plants,
often most complicated
in structure and per-
fectly fitted for the
capture of insects, can,
according to Darwin,
who, for the first time,
demonstrated their
mode of action, only
have gradually arisen
by a slow process of
selection. The pitcher
plant of Borneo — e.g.,
Nepenthes villosa
(Fig. 45), has its leaves
modified into a com-
plete pitcher-like struc-
ture, which contains a
digestive fluid capable
of dissolving nitrogen-
ous substances. Insects
falling into this pitcher
are caught as in a trap,
for the rim is equipped
with downward-point-
ing teeth, effectively
preventing their exit.
The leaf of our sundew,
Drosera rotiindifolia
(Fig. 46), has the same
power of digesting
animal food. Small in-

, ^ . ^. . sects ahghting on the

5/. Stalk of leaf ; 5/>i'. Its apex ; FA. pit- . ^.^icxcf^ of its

Cher; i?.marginwith incurved spines. Slimy SUrtace OI lib

(From" The Evolution Thiory;' by A. Weismann.) IcaVCS are Capturcd by

DARWINISM

127

Fig. 45. — Pitcher of Nepenthes
Villosa. (After Kemer.)

the " tentacles." which, curving in upon them, help to

'^tlhiTone of the most wonderful -- ^^d.^:
is that between flowers and insects. As early as 179:^
German naturalist,
Christian Konrad
Sprengel, discovered
what he quaintly
called " the secret of
nature," namely, the
fact that flowers are
specially constructed
to attract the visits
o^ insects, so as to be
fertilized by theni.
Jt was not until
Darwin investigated
cross-fertilization in
the Ught of natural
selection that this
subject found its full
recognition. Indeed,
I the fertilization of
^pflowers by insect
le agency now forms a
fl' favourite illustration
^ of the popular writer
on natural selection.
The first fact to be
noticed is, that all
higher plants which
are fertilized by the

FiG 46. - The Sundew {Drosera

Rotundifolia). (After Kemer.)
(From " The Evolution Theory;' by A. Weismann,)

:^;d tr;:U n ^ng wafted about by the air. have in
^nsDicuouVaowers, as the hazel, birch, grasses etc. The
'jSS Tthe othe'r hand, which are fertmz«i ^ m^i«
«f insects have conspicuous flowers. Whilst the plants
i:ZSk o'their honey, they are in turn benefited by

-;»'^-{tf?,.'g^?iWtJ|JllBl?rJ)IWl4^!Ui»lfi;.i.ilJf^

muMmiii'iiiii— I'nii- HI

128 THE FIRST PRINCIPLES OF EVOLUTION

their " unbidden guests " through the cross-fertilization
which the latter effect during their visits. For without
them this would be impossible. As Darwin has shown,
cross-fertihzation is one of the essentials for a strong and
vigorous stock.

We have not only the general well-known features in
flowers to attract insects, as bright colouring, particular
markings, etc., serving as guides to the nectaries, but in
a great many cases there exist very special adaptations,
leading with sureness to the fertilization of the flower by
its insect visitors. The insect, while seeking for honey,
must collect pollen from the stamens of one flower, and
convey it to the pistil of the next it may frequent. Now
we find the most perfect mechanism in flowers to insure thi:
cross-fertiUzation. Thus the meadow sage (Salvia pratensis)
is fertiUzed by the bee, which, entering the corolla, presses
upon a short, handle-like process of the stamens. In
consequence the pollen-bearing anthers, previously hidden
within the helmet-Uke upper 'lip of the flower, turn down-
wards upon the intruding insect, dusting its back with
pollen. Now, when the bee visits another more mature
flower, the pollen is rubbed off on to the stigma of the pistil,
as the latter in the mature stage is bent downwards,
just in position to meet the back of the bee (Fig. 47).
Darwin has described the most marvellous adaptations for
cross-fertiHzation in orchids. Very often the circle of
visitors of a given kind of flower is limited, sometimes to ;
only one kind of insect. In such cases the inter-relation
between flower and insect is carried out minutely in every
detail of structure. Thus some flowers with long corolla
tubes can only be fertilized by butterflies which have a long
proboscis. We have mentioned previously that the mouth-
organs of bees and butterflies have developed from the
ordinary biting organs of primitive insects, and we must
assume that their evolution has taken place pari passu
with that of the flowers they frequent. This close inter-
relation could have been attained only by a selective

DARWINISM

12^

\ h

process, bringing about at each successive step a mutual
adjustment between flower and insect. On the Lamarckian
view it is hard to see how such a minutely speciahzed
adaptation between plant and animal organisms could
have ar-.en by mere " strains and stresses. How, m tne
first instance, did a regular flower become an irregular
one, seeing that the external stimulus was not regularly
applied to one and 5/'

the same petal of the

flower ? Further- /^^^^^^^^•m^^^jg^'

more, how can the
same stimulus be
supposed to have
had such varied
effects in different
flowers? And fur-
ther still, how can ^::^:-m/ \ -^^-^^^^p^ss^m rr
the elongation of a M^ mL-.-^.>v^:i^^^^^M^l V

corolla tube be ex-
plained on Lamarck-
ian principles so as

to lead to an exact Fig. 47- -Flowed ?L,^r TM^llfrT'^
agreement with the KSo^v^a Pratens^s). (After H Mailer.

Ipntrfh of a butter- si'. Immature anthers concealed in the
length 01 a ouiier . ^ ^^^^^ „ ^^ ^^^ ^^^^^ . ^^.^ jj^^ture

fly s proboscis i Un anther lowered ; gr\ immature stigma ;
the theory of natural gr^. mature stigma ; t/ lower lip of
selectionlhis mutual corolla, landing-stage for the bee.

adaptation is easily (From " TU Evolution Tkeoryr by A. Weismann.)

pLwers'^va^, and'so do insects. The best adapted types
being mutually useful to each other, had the greatest
chance of surviving, and so handed down their structures,
which, by continual selection, were more and more

'Tno'thtr contrivance evolved by natural selection for
the achievement of cross-fertiUzation m plants is the
phenomenon of heterostylism, which also was first dis-

DARWINISM

131

130 THE FIRST PRINCIPLES OF EVOLUTION

covered and explained by Darwin. There are some flowers,
as the primrose and the cowslip, which possess two forms,
one having a long style and short stamens, the other a
short style and long stamens. Now, it was found by Darwin
that such dimorphic flowers yield the most and best
progeny when the two different forms are crossed with each
other, while each form is almost barren if fertilized by its
own pollen. Looking at Fig. 48, we see that if a short-styled

Fig. 48. — Cowslip (Primula Verts).
A , Long-styled form ; B, short-styled form.
(From " Darwinism;' by A, R, WaUace.)

flower is visited first by an insect, the pollen from the long
anthers will readily be deposited on a long-styled flower,
the short style of the other form being out of reach. On
the other hand, should a short anther be visited first, it
will often happen that its pollen is carried on to a long
style, thus producing self-fertihzation. This explains the
fact that the wild short-styled plants are always more
productive in seeds, seeing that they can only be fertilized
by the other form, while the long-styled plants often remain

barren, though fertilized with the pollen of their own
kind. These phenomena become more complicated in
trimorphous flowers, in which styles and stamens have
each three forms. Here Darwin distinguishes between
legitimate unions, those which are effected by the pollen
of a stamen equal in length to the styles of the fertilized
flowers, and illegitimate unions, where the lengths of stamens
and fertiUzed styles are unequal. The latter are com-
paratively or wholly sterile.

Finally, we must point out some beautiful adaptations
in plants for the purpose of dispersing their seed. Many
seeds, being small, have various contrivances, such as wings,
plumes, etc., in order to be wafted about by the wind.
Others have hooks by which they attach themselves to the
fur of grazing animals ; while others, again, being bulky
and hard, are enveloped in an edible pulp, which is often
attractively coloured, in order to be eaten by animals.
These, passing the seeds out, well manured, give the plant
a chance of taking root, often far away from its original
position.

(6). Animal Colouration.

The problem of colouration in the organic world has
become, like so many other biological questions, a special
subject for scientific study ever since Darwin showed that
the evolutionary principle can successfully be applied to
its elucidation. We have seen how the bright colours
of flowers can be accounted for by progressive adaptations.
We shall find that most of the phenomena of colouration
in animals can be explained by means of natiu'al selection ;
though, be it said here, we must guard against pushing this
explanation too far, as has been done by some Darwinists.

Before Darwin's time no special meaning was attributed
to the colour of animals, the general opinion being that it
was due to the action of light and heat. But though it is
true that the particular colours of an organism must be
referred to certain intrinsic physical and physiological

132 THE FIRST PRINCIPLES OF EVOLUTION

causes, it is otherwise with the arrangement of the tints,
which, as F. E. Beddard has pointed out, must be dis-
tinguished as colouration from the mere colours. The
patterns to be seen in various animals can be attributed to
a large extent to the action of natural selection, for they
can often be shown to be a survival factor in the struggle
for life.

Thus many animals are protectively coloured by re-
sembling more or less the general colouring of their natural
surroundings, which enables them to conceal themselves
for defensive or aggressive purposes. A good example is
the common hare, which, when squatting down on the
ground, is hardly distinguishable from a lump of brown
earth. Arctic animals are generally white, either per-
manently throughout the year, as the polar bear, the
snowy owJ, etc ; or only during the winter season, as the
Arctic fox, the ermine, the ptarmigan, and so on. This
accords with the needs of the respective animals ; for those
which have a dark summer coat live in regions free from
snow in summer. That adaptation is the cause of the
white fur is evidenced by those cases which, on first appear-
ance, seem to be exceptions to the rule. The sable and
the musk-sheep are brown, while the Arctic raven is black,
all the year round. But in these cases there is no need
for special colour protection ; for the sable frequents trees,
and is easily concealed among the dark branches ; the
musk-sheep, being gregarious, gains more by its dark colour
than if it were white, as stragglers can thus easily find their
flock ; while the raven is a carrion feeder, and therefore
needs no concealment. The sandy, tawny colour of the
animals of the desert is well-known, as instance the lion,
the camel, and many others. It would seem as though
animals like the tiger, the jaguar, etc., with their dark
stripes and spots, would be very conspicuous ; but they are
well concealed in their natural haunts among the dappled
shadows cast by jungle grass and tree branches. Nocturnal
feeders are mostly of a dusky colour, witness the rat, mouse,

DARWINISM

133

bat, and owl. There are hosts of animals frequenting trees
and shrubs which are protectively coloured. We need
only mention the green frog, the green snake, lizards, beetles,
grasshoppers, butterflies, moths, etc., and, chiefly, cater-
pillars. It is a significant fact that, while the green butter-
fly, which rests with upturned wings, has its green colour
developed on the underside of the wings, in the green moths
the visible upper side of the wings is of that colour. That
there are so few green birds in temperate regions is ex-
plained by the fact that birds have a better chance of
survival in winter among the bare branches of trees by
being in general a dull, rusty brown. Whether the white
underside of birds, whales, dolphins, etc., and of the flat-
fish is due to natural selection, is very doubtful. As
to tlie birds, the idea that the white surface harmonizes
with the bright sky is certainly erroneous, for it would show
dark from below ; while the experiments by Professor
Cunningham seem to indicate that some environmental
factor — probably light — is the real cause of the differentia-
tion in colour between upper and lower sides of the
flat-fish.

Protective colouration extends even to the eggs of
animals, for natural selection commences its action at the
very beginning of an animal's existence. The eggs of
insects are often sympathetically coloured in agreement
with the object upon which they are laid — ^green on leaves,
and brown on the bark of trees. Originally the eggs of
birds were most probably white, and they remain so when-
ever they are hidden in covered nests or otherwise between
earth and stones. Tinted and richly spotted eggs, on the
whole, agree in their colouring with their surroundings,
as, e.g., in the case of the plover, which lays sand-coloured
eggs on the beach.

The phenomena of colour in caterpillars have been most
attentively studied by Weismann, Poulton, and others.
We have already mentioned that a great many caterpillars
feeding on leaves and grasses are green, and have thus a

134 THE FIRST PRINCIPLES OF EVOLUTION

protective resemblance to their environment. But whether
this is brought about in all cases by natural selection is
doubtful, for Poulton has shown that the green colour is
due in many instances to physiological causes : to the food
contained in the alimentary canal, or to the green colour

of the blood or of the skin.
Weismann explains the longi-
tudinal striping found in certain
caterpillars (Satyridce) frequenting
grasses as a special adaptation,
since the stripes add to their
concealment among the grasses
(Fig. 49). In a similar manner
other caterpillars of the same
family Hving on bushes and trees
have diagonal stripes, which,
breaking up the surface of the
large green body, increase its
resemblance to a ribbed leaf
(Fig. 50). Now, according to
Beddard, the longitudinal stripes
of the Satyrids are not only
characteristic of the grass-feeding
caterpillars, where they have
adaptive value, but they appear
also in larvae feeding in the
interior of reeds or upon the
leaves of trees, in which cases they
are certainly useless. It would
seem, then, that the longitudinal
striping of the Satyridae is rather
a race characteristic, common
to a whole group of caterpillars, and is not due to natural
selection in special, the more so as such stripes are no
infrequent features among other classes of animals. Once
existing, they may, of course, serve the function of pro-
tective colouration. Indeed, according to the theory of
Professor Eimer, there occurs, independently of natural

DARWINISM

135

Fig. 49. — Caterpillar
OF A Satyrid, striped
Longitudinally.

(From *'7'Ae Evolution Theory"
by A. IVeismann.)

selection, a regular succession of markings in ammals.
Longitudinal stripes are succeeded by spots, which, by
coalescing, later form cross-bars ; the uniform colouration
being the last term in the series.

There are some caterpillars which show two kinds of
colour adaptation, being either green or brown. In the
large Emerald moth (Geomeira papilionaria) this di-
morphism offers a distinct advantage to the larvae, for
their resemblance to the green or brown catkins of the
birch, which they frequent, is thereby greatly enhanced.
The double colouration in the caterpillars of the Sphtngtda
is explained by Weismann as a new adaptation in progress
of transformation ; for not only is the green variety rarer,
on the whole, as in the Convolvulus Hawk-moth (Sphinx

Fig. 50.— Caterpillar of the Eyed Hawk-Moth [Smertnthus

Ocellatus), striped Diagonally.

{Front " TAe Evolution Theory ;' by A. WiesmMnn.)

convolvuli), but in other casesr— as, e.g., in the Privet Hawk-
moth (S. ligustri)— the same larva changes during its later
stages from green into brown ; while in others, again, all
the larvae are brown. The brown colour is evidently more
protective than the green, and is in process of superseding it.
The latter instance leads us to the group of cases with
variable colour-resemblance— that is, the animals in ques-
tion have the power of changing their colour in accordance
with their surroundings. We have first of all the seasonal
change, of which we have already given examples when
speaking of Arctic animals. A change of dress also takes
place in temperate regions in a number of birds and deer,
though, be it said, such change cannot always be considered
adaptive. Seasonal dimorphism is further to be found in
butterflies, in certain moths, and other insects. Another

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136 THE FIRST PRINCIPLES OF EVOLUTION

kind of alteration of colour is characteristic of many
animals, from fish downward to cuttle-fish, which are able
rapidly to adjust their general colouring in harmony with
the changing tints of their surroundings. Thus, trout and
sole are dark in muddy water and light on clear ground ; the
common frog adapts its colour from green to a dark brown,
according as it rests among leaves or on the ground ;
while among reptiles the chameleon is proverbial for its

changing colours. We may reckon all these
phenomena to be due to natural selec-
tion. Poulton has shown in a remarkable
series of experiments that the chrysalids
of certain butterflies change their colour
according to the prevailing tint of the

Fig. 51. — Stick Insect.

(From " Darwin and afUr Darwin," by G. J. Romanes.)

surroundings they are reared in. But as in some cases
colours were produced which are very rarely seen in
nature, in others, again, colours which are never to be
found in the natural state, it is at least doubtful how
far this colour change may be attributed to the action
of natural selection.

We have so far considered colour resemblances where the
individuals concerned harmonize in a general way with
the prevailing tints of the environment. But colour

■PMVMMW

DARWINISM

137

adaptation in animals may go much further. There is a
whole series of cases where the living orgamsm mutates a
particular object, often with astonishing fideUty, so that
concealment is most effectively attained. Such cases are
most prevalent among insects, though they are not ex-

FiG 52 —Stick Caterpillar {Selenia Tetralunaria), seated on a

Birch Twig. (Natural size.)

K, Head ; F, feet ; m. tubercle, resembling a " sleeping bud."

(From " The Evolution Theory," by ^. Weismann,)

clusively confined to them. We have first of all a number
of locusts of the tropics, the so-called stick-insects
{PhasmidcB), which, with their long bodies and irregular
outstretched limbs, resemble a dead branch with lateral
twigs (Fig. 51). The geometer larvae have, as a general

138 THE FIRST^PRINCIPLES OF EVOLUTION

rule, twiglike shapes. In some of them this charac-
teristic is further enhanced by a close likeness in colour
and general appearance of the body. A caterpillar hke
that of Selenia tetralumria (Fig. 52), resting perfectly
motionless at an angle from the stem, has a most deceptive
resemblance to a branchlet, which is still more increased
by little protuberances of the body, imitating buds or
irregularities of the stem. It would seem here that, while
the original configuration of the geometers is given initially
in their constitution, this special feature was improved upon
by the action of natural selection. There are some moths,
too, which when resting with the wings close upon the

A B

Fig. 53. — Stick Moth {Xylina Vetusta).

A, In flight ; B, at rest.

{From " The Evolution Theory" by A, Weismann)

body look like bits of decayed, lichen-covered wood, as
e.g., the Buff- tip moth {Pygara lucephala) and the Xylina

(Fig. 53).
Resemblance to leaves is not an uncommon occurrence

among insects. The winged species of the Phasmidae
(already mentioned), with their veined wings, their leafy
expansions on legs and thorax, furnish a very good example
(Fig. 54). Closer still is the approach to a leaf-Uke struc-
ture in various species of butterflies. The most famous
of these is the KaUima butterfly of India. Its wings, when
upturned, represent on their underside a perfect copy of
a leaf with a midrib and a regular succession of side veinings.
Differently coloured spots on the wing imitate patches of
decay and mildew, while the prolonged tail of the hind-

DARWINISM

139

(

Fig. 54. — Leaf Insect.

Fig. 55. — Kallima Butterfly.

A, Upper surface ; B, under surface.

(Both from " Darwin and after Darwin," by G. J. Romanes.)

I40 THE FIRST PRINCIPLES OF EVOLUTION

wing, which touches the stem in the sitting posture of the
butterfly, makes it appear as though the leaf was directly
growing out of the stem (Fig. 55). One cannot but
explain all these instances as adaptive modifications,
brought about step by step through natural selection ; for
it is obvious that the closer the resemblance of a given
individual to a leaf, the greater would be its chance of

Fig. 56. — Indian Mantis {Hymenopus Dicornis) in Active Pupa

Stage.

{From " Colours of Animals;' by E. B. Poullon,)

survival. A most extraordinary instance of special pro-
tective resemblance is that of certain moths and spiders,
which by their general form and colour produce the im-
pression of patches of bird's excreta. The little Chinese
Character, Cilix spinula, and many grey and white geom-
eters, when resting on a leaf with outstretched wings
present this appearance. The same disguise is used by
certain spiders to attract prey within their reach. Alluring

DARWINISM

141

devices occur also in other animals. For instance, the
Indian Mantis {Hymenopus bicornis) imitates with its
flattened legs the petals of a flower, and thus captures
other insects (Fig. 56). As an instance of special re-
semblance among higher animals we may mention that
a certain species of fish has frond like appendages, which
make it nearly indistinguishable from bunches of sea-
weed ; while an Australian lizard (Moloch horridus) is
covered with spiny excres-
cences in imitation of the
thorny bushes among which
it lives.

Here we may also reckon
those cases where harmless
and relatively defenceless
animals, when in danger, take
on an attitude of defiance,
presenting a terrifying ap-
pearance, in order to frighten
of! their enemies. A typical
example is the larva of the
Puss moth (Cerura vinula).
When disturbed, it with-
draws its head into the first body-ring, which, with
its inflated bright red margin and two intensely black
eyehke spots, produces the impression of a large,
flat face (Fig. 57). Perhaps the eyelike spots of the
Eyed Hawk moth, giving in the defiant attitude the
appearance of a head with staring eyes, belong to the
same category (Fig. 58).

This leads us on to another series of colour phenomena
in animals, where the colouration, far from adding to the
concealment of the individual, has been developed for the
contrary purpose — namely, to render its possessor more
conspicuous. A. R. Wallace would explain in this manner
certain regular markings in gregarious mammals, birds,
etc., which, being prominent and easily seen from a dis-

FiG. 57. — The Larva of the
Puss Moth in its " Terrify-
ing" Attitude. (Natural
Size.)

(From " Colours of Animals" by E. B.
Poulion.)]

142 THE FIRST PRINCIPLES OF EVOLUTION

DARWINISM

143

Fig. 58.— The Eyed Hawk Moth in its '^Terrifying " Attitude,
(From "The Evolution Theory" by A. Weismmn.)

Fig. 59. — Gazella Scemmeringi.

{From "Darvinism," by A. R, Wallace,)

tance, serve as a common means of recognition to the
members of the flock. They would also, in his view, aid
the two sexes to distinguish between members of their
own and of closely resembling species, and thus prevent
the evil of intercrossing. We figure here a gazelle (Gazella
scemmeringi), with its white patches on face and hind-
quarters (Fig. 59), and the banded recognition marks of
three African plovers (Fig. 60). It must be pointed out,
however, that G. J. Romanes and Professor Lloyd Morgan
have adduced a weighty objection against Wallace's con-
tention that these marks have been developed by natural
selection for the specific purpose of preventing inter-
crossing of aUied forms. Recognition marks must
already be in existence in order to allow of the differentia-
tion between the species, and cannot therefore have been
evolved by that process of differentiation. Or, as Professor
Lloyd Morgan has put it : " The recognition marks were
not produced to prevent intercrossing, but intercrossing
has been prevented because of preferential mating between
individuals possessing special recognition marks." A some-
what different interpretation has been given to what has
been called "danger-signals" of certain animals. The
rabbit, for instance, though protectively coloured, shows
when running to its burrow a white upturned tail, which
renders it very conspicuous. Here the recognition mark
serves to indicate approaching danger to other rabbits
which may be near. It thus acts as an important means
of mutual protection.

True warning colours, however, have the purpose of
rendering their possessor conspicuous to its enemies, so
that it may remain free and unmolested from their attacks.
It was Wallace who first suggested this explanation, in
order to account for the brilliant colouring of certain
caterpillars; and the principle has been found to apply
not only to a large number of insects, but also to higher
classes of animal life. Warning colours are, as Wallace
rightly conjectured, accompanied by strongly distasteful

144 THE FIRST PRINCIPLES OF EVOLUTION

DARWINISM

143

Fig. 61.— Braziman Skunk.

nauseous. P^^^f "f toS^flS^it^s IZ'Z^^^-
defence a very dangerous ^5° „ ° eptiles we have vanous

attacks of other^^rJ.^.tS^^. «•«- th« Coral snake
brightly coloured poisonous snakes- . «^^^^ y^^k and

(E/«/.s) in t'°Pi^^,^"^Sariv ringed black and yellow ;
U and the ^y-^^^^^'^'^^^Le generally coloured pro-
though poisonous snakes are more g ^^

mmmfia^

146 THE FIRST PRINCIPLES OF EVOLUTION

tectively. The only known poisonous lizard is the Helo-
derma of North America, which is prominently blotched
with black and pinkish-yellow. Of amphibians Mr. BeU
describes a frog of Santo Domingo which " hops about in
the daytime, dressed in a bright livery of red and blue,"
and which was found on experiment to be unpalatable.
Other frogs of the same district are soberly coloured, hide
during the day, and only come out at night to feed. The
common European salamander {Salamander maculosa),
too, with its yellow blotches on a black background, is
most probably poisonous.

The most numerous instances of warning colouration
are found among butterflies, in aU stages of their existence.
We have first of all brightly coloured caterpillarsr— as, e.g.,
those of the Magpie moth (Abraxas grossulariata) , the
Buff-tip moth {Pygcera hucephala), and the Cinnabar moth
(Euchelia jacohece) . They have black and yellow or orange
markings or rings. The latter two moths are rendered
still more conspicuous by being gregarious. These larvae
have been observed to be generally nauseous and dis-
tasteful to their would-be devourers. Other caterpillars
possess irritant hairs, sometimes, as in the Tussock moth,
arranged in tufts or "tussocks." These are conspic-
uously coloured, and offer a first point of attack to the
enemy, which, of course, withdraws quickly, with no greater
loss to the caterpillar than that of a bunch of hairs. Poulton
found that the chrysaHs of the Magpie moth, being con-
spicuously coloured black with yellow bands, is obnoxious
like the larva and the moth itself. The latter is very
attractively marked with yellow and black on a white
ground. Other moths are similarly gaudily coloured, as
also a host of butterflies, all being inedible. Such butter-
flies often possess very conspicuously marked hind-wings,
which frequently end in spurs and elongations, thereby
directing the enemy's attack to the most obtrusive, but
least vital part. Lastly, we must mention gaily coloured
nauseous beetles, as the Ladybird, and wasps, hornets,

DARWINISM

147

{

etc., which advertise their dangerous stings by their
conspicuous stripes of contrasted black and yellow.

The theory of warning colouration presupposes that the
enemy recognizes the highly coloured species before the
attack has led to the destruction of the victim. It would
be of great advantage, therefore, that the enemy should
learn to discriminate quickly the palatable from the un-
palatable species. Now, this object is furthered by the
general scheme of warning colouration, which is on the
whole very simple and uniform. It consists mainly of
black (or other very dark colour), which is contrasted either
with white or with yellow, orange, or red. The pattern
consists of stripes, rings, or spots. Therefore, there needs
to exist only a simple association between this colour
arrangement and unpalatability. Among inedible butter-
flies the colouration agrees to a remarkable degree in an
immense number of species. This, according to Fritz
Miiller, offers the great advantage that the nimibers of
victims which succumb to the attacks of inexperienced
enemies is proportionately diminished in each species.

We cannot leave this subject without drawing attention
to a serious objection which has been made against the
theory of warning colouration. This theory presupposes,
as was stated before, that the protected species pos-
sesses some offensive quality, be it of taste, smell, etc.,
of which it gives its enemy timely notice by its con-
spicuousness. But now Beddard has shown that in a
nimiber of instances such bright-coloured species are not
rejected as food, as they ought to be according to the
theory ; while, on the other hand, some distasteful species
are soberly coloured. Dr. Eisig would explain brilliant
colours in general as the incidental result of pigmentatic n,
which in itself causes the distasteful character, so that,
contrary to the accepted opinion, bright colouring would
be the cause of the inedibility of the species, and not vice

versa.

We have just mentioned the fact that among inedible

148 THE FIRST PRINCIPLES OF EVOLUTION

DARWINISM

149

butterflies there is often in allied groups one prevalent
t3^e of marking and colouring. We must add that some-
times an unpalatable species is mimicked by another
which is not related to it. Thus the Danaids, inhabiting
the same regions of tropical America as the Heliconias,
show the same peculiar arrangement of colour and wings
as the latter. This case leads us on to the phenomena of
true mimicry, where the mimicking species itself is harm-
less, but imitates another inedible species in its outward
appearance, and thus gains the advantage of being mis-
taken for the mimicked immune form. This is the ex-
planation which was first advanced by Bates in 1862, and
it has since been found applicable to a great number of
cases, not only in the order of Lepidoptera, but also of
other insects, and even among higher animals. The
imitating forms occupy the same regions as their immune
protot5^es, and are generally much less numerous. The
classical example of mimicry is that discovered by Bates
among the butterflies on the Amazon, in South America.
He found that among the abundant Heliconidae of that
region, which belong to the offensive, brightly coloured and
slow-fl5ang species, was mixed a small number of Pieridae,
or " whites," which, though themselves harmless, resemble
the Heliconidae very closely (Fig. 62). Not only this, but
different species of the mimicking family imitate par-
ticular species of the Heliconias inhabiting the same
localities. Similarly we find in Africa two other types of
inedible butterflies, the Danaidse and Acraidae, both being
mimicked by a number of edible butterflies.

There are some interesting details connected with the
phenomena of mimicry. First of all, we find that it is
often the females only which deviate from their type and
imitate another immune form. It is apparent that the
egg-laying female is in greatest need of protection. In other
cases the males show more or less indication of a protec-
tive change, which is evidently in process of development.
Other instances there are again where the males follow

one pattern and the females another. It is not at all rare
to have a group of butterflies mimicking at the same time
a number of immune protot3^es, according to their oppor-
tunities and the districts they inhabit. Thus the male

Fig. 62. — Mimicry among Butterflies.

Methona psidii (Heliconidae) and Leptalis orise (Pieridae).

{From "Darwinism;' by A. R, Wallace,)

Swallowtail {Papilio) of Africa shows the typical pattern,
while the female deviates largely from it, being without
the characteristic " tails." But there are no less than
three or four different kinds of females, each imitating a

150 THE FIRST PRINCIPLES OF EVOLUTION

specific Danais, according to the region they frequent.
Contrariwise, an immune species may be copied by a host of
other butterflies.

Coming to moths, we find an extension of mimicry to
prototypes not belonging to the same order as the mimick-
ing form. The Hornet Clearwing imitates a hornet (Fig. 63) ,
while two of the Hawk moths, called Bee-hawks, {Sesiidce)
resemble humble-bees. In fact, hornets, wasps, and bees
are frequently mimicked by other harmless insects, the
most common example being that of certain flies which on
a superficial glance look like bees or wasps, though they
have only two wings, instead of four, like the latter

(Fig. 64). Spiders have
been found which have the
appearance of ants, but
it is doubtful whether this
disguise enables them to
attack the ants or to avoid
destruction by birds. A
most wonderful example of
mimicry is that between
the leaf-cutting ants and
certain insects in tropical
America. The ants carry
bits of leaf on their backs,
and the insects completely imitate ant plus leaf by having
their bodies expanded into a thin, flat, leaf-like appendage.
Of mimicry among the higher animals there is little to say.
Some innocuous snakes don the attire of others that are
venomous. Dr. Seitz described a Humming-bird Hawk
moth which imitates a humming-bird ; but whether this con-
stitutes a case of true mimicry is, to say the least, doubtful.
The instance of the caterpillar which, on being disturbed,
assumes the appearance of a vertebrate face has already
been mentioned, and may be reckoned under the head of
mimicry, as also a number of similar cases described by
Poulton.

Fig. 63. — Hornet Clearwing.

{From " Animal Colouration," by F. E,
Beddard.) .

DARWINISM

151

One of the conditions of mimicry, according to Wallace,
is that the mimicking species should be less numerous than
the mimicked model, but this condition is not always
fulfilled. Another essential feature is that both forms
should inhabit the same district. How otherwise could
there be given the opportunity for developing the pro-
tective device ? Now, there are instances — and they are

VoLuceU/l INANS.

VksPA Vulgaris*

Vol. BoMBVLArJs. Bombi/s LapidariUs.

Fig. 64. — Mimicking Flies.
Volucella, fly ; Vespa, wasp ; Bombus, bee.

{From "Darwin and after Darwin;* by G, J. Romanes.)

not infrequent— where the two identical-looking forms do
not inhabit the same country. For instance, there is a
Sesiid moth which resembles a humble-bee, but no humble-
bee exists where the moth lives. This would seem to be
a serious argument against mimicry, to which must
be added another fact— namely, that mimicry has been
found between certain organisms where it cannot possibly
have any useful purpose, and therefore cannot be attributed

tmmmm

mmmm

mmm

wit

152 THE FIRST PRINCIPLES OF EVOLUTION

to the action of natural selection. Indeed, resemblances
may be due to other factors — to affinity of descent, to the
.action of similar environment, etc. Thus it becomes
evident that not all cases of resemblance between forms
frequenting the same district are to be put down as
instances of mimicry. For those cases where the two
mimetic forms do not commingle, as that of the moth and
the humble-bee just quoted, Mr. Scudder has advanced
two possible explanations. It may be that the bee which
served as a prototype has died out in the district, or the
moth may have migrated from its original habitat.

There are still left cases of animal colouration which do
not find their explanation on any of the above-named
principles, but are attributed by some authors to the action
of sexual selection. With that subject we shall deal
later on.

/ So far we have dealt with adaptations due to naturaii
selection which concerned mainly morphological traits.
I But in order that such structures may prove useful to
! their possessors, they must be associated with proper
I functions. And, indeed, we find that instinctive behaviour
\ prompts the protected animal to adopt the appropriate
V attitude which serves as a means of its survival. Of what
use, for instance, would protective colouration be to an
organism that would not lie motionless, so as to be mis-
taken for a part of its natural surroundings ? On the other
hand, an animal like the caterpillar of the Puss moth
would not gain anything by its peculiar colouration did
it not in time of danger execute the necessary movements
in order to produce the aggressive resemblance to a verte-
brate face. The mimicking species of butterflies, too, as
we have seen, have the slow, deliberate mode of flight of
their immune prototypes, which helps them to be easily
identified by their enemies as a species to be avoided. In
fact, physiological functions not less than morphological

DARWINISM

153

traits come under the sway of organic evolution, and have,
as Darwin pointed out for the first time, been developed
exclusively for the benefit of the species possessing them.
They, too, are important factors in the survival of the
fittest, and have to be explained on the same principle.

In the first instance, instincts vary just Hke anatoniical
features. Everybody knows that the faculties of the vanous
pups in a Htter of dogs differ considerably from the out-
set ; in fact, the breeder chooses accordingly for his special
purpose. And there is sufficient evidence to show that
instincts vary also in a state of nature. Thus, for mstance.
Prof. Lloyd Morgan quotes Mr. BlackweU as stating that
" birds of the same species possess the constructive powers
of nest-building in very different degrees of perfection." If,
then, certain variations of such given faculties should prove
more useful than others in the struggle of life, they would
be preserved by natural selection and gradually perfected.
It is in this manner that we must account for the highly
developed instincts of certain insects, however compUcated.
The evidence here, as in other cases of evolution, cannot be
obtained directly by observation, but the gradual steps in
the formation of a given instinct can only be followed m
various collateral lines of the related species. Darwin has
given a most beautiful example in the cell-making instincts
of the hive-bee. It is weU known that the hive-bee builds
a most regular comb of hexagonal cells which intersect
at thek bases ; while the humble-bee, at the other end of
the scale, fills the old cocoons with honey, " sometimes
adding to it short tubes of wax, and likewise making
separate and very irregular rounded cells of wax." Be-
tween these two extremes we find the Mexican Melipona
domestica. The ceUs of the latter " are nearly spherical
and of nearly equal sizes, and are aggregated into an
irregular mass. They are always made at that degree of
nearness to each other that they would have intersected
or broken into each other if the spheres had been com-
pleted : but this is never permitted, the bees building

^ I

154 THE FIRST PRINCIPLES OF EVOLUTION

perfectly flat walls of wax between the spheres, which thus
tend to intersect. Hence, each cell consists of an outer
spherical portion, and of two, three, or more flat surfaces,
according as the cell adjoins two, three, or more other cells.
When one cell rests on three other cells — ^which, from the
spheres being nearly of the same size, is very frequently
and necessarily the case — the three flat surfaces are united
into a pyramid ; and this pyramid, as Huber has remarked,
is manifestly a gross imitation of the three-sided pyramidal
base of the cell of the hive-bee." The close arrangement
of the intersected hexagonal cells is evidently for the bee
a great saving of wax and labour, and must have been
attained gradually by a process of natural selection.
Darwin would explain in a similar manner the curious
instinct of the cuckoo, which lays its eggs in the nest of
other birds ; as also the slave-making instinct of certain
ants. We cannot possibly enumerate here the endless
functional adaptations in animal and plant life due to
natural selection, be they for the purpose of self-preserva-
tion or of sexual propagation. We must not omit, how*
ever, to make mention of those wonderful cases where two
organisms of entirely different classes have become
mutually adapted to each other, so that they always live
together, each one deriving thereby benefit from the other.
Such instances of " symbiosis " occur either between two
animal or two plant organisms, or between animal and
plant. Thus there are hermit crabs living in shells covered
with a colony of polypes. The latter have in certain cases
become modified, and excrete a stinging fluid by which they
ward off attacks against their host (Fig. 65) at the points
where the protective threadhke individuals of the polype are
arranged along the margin of the shell. The crab repays
this service by bringing food within the reach of his pro-
tectors. The roots of many of our trees are covered with
a network of fungi, which, whilst supplying the tree with
salts and water, receive in their turn nourishment from the
roots, Finally, there are the cases of sjonbiosis between

DARWINISM

155

animal and plant organisms, of which we only mention that
of the fresh-water pol5q)us {Hydra viridis) with an alga.
The green alga furnishes ready oxygen to the polypus,
which in its turn offers within its interior a quiet habitat
to its guest.

It is largely in reference to instincts that the question
arises how far the Lamarckian factor of use-inheritance

Fig. 65. — Hermit Crab {E) within a Gasteropod Shell, on which
A Colony of Podocoryne Carnea has established Itself.
(Slightly enlarged.)

From the common root-worm (which is not clearly shown) there
arise numerous nutritive pol5rps with tentacles {np), among
which are spine-like personae {stp) ; and on the margin of the
moUusc shell a row of defensive individuals (wp). F, Antenna ;
Au, eyes of the hermit crab.

{From " The Ewlution Theory," by A. Weismann.)

is a potent means of evolution. Though we cannot enter
here into the details of this problem, which will be dis-
cussed in full later on, we must just refer to a few points
which have been raised with regard to instincts. Observa-
tion would seem to tend towards the conclusion that
instincts have originated by the accumulation of the in-

156 THE FIRST PRINCIPLES OF EVOLUTION

herited effects of acquired habits. It is a well-known fact
that actions at first produced consciously become after
constant repetition stereotyped into habits, and are per-
formed automatically. This is the way in which the
Lamarckist would explain the origin of all instincts. They
are, according to Prof essor Wundt and G. H. Lewes, heredi-
tary habits. In proof of their contention they would
submit, firstly, that habits are formed in every individual,
and, secondly, that there are a great number of instincts
which, not having any survival value, cannot possibly have
evolved by the aid of natural selection. Against this the
selectionists point out : (i) It has to be proven in every
single instance whether a certain action is truly instinctive.
Often all that is instinctive is, as Professor Lloyd Morgan
has shown so beautifully, merely a predisposition to
acquire the habit in question, while each individual in
its turn has to learn it anew— as, e.g., the knowledge which
young birds acquire of avoiding unpalatable food, of drink-
ing water, etc. (2) There are cases where the instinctive
action is only performed once in the lifetime of the in-
dividual, the formation of a habit thereby being excluded.
Yet the instinct shows itself perfect in each successive
generation — as, for instance, in the spinning of the cocoon
by caterpillars, etc. The neuter ants and bees are sterile ;
therefore their instinctive social behaviour cannot possibly be
handed down by them to the next generation. Mr. Perrier
tried to overcome this last objection by assuming that the
habit of the neuter insects were developed and fixed by
heredity before they became sterile. But in this case, Lloyd
Morgan argued, the effects of disuse of these special instincts
in the individuals, while fertile, should have led, according
to the same principle, to their gradual degeneration and
disappearance.

The final decision in the matter of instinct, as in the
whole problem of use-inheritance, depends on the answer
which is given to the question : Are acquired characters
inherited ? This point we shall discuss later.

DARWINISM

157

(i) Human Faculty.

How far has man to be included in the general scheme
of organic evolution ? We have seen in the chapter on
morphology that there exist many vestigial structur^ in
the human body linking man unmistakably with his animal
ancestry. Darwin himself was fully aware of the conse-
quences of his theory of evolution, and indicated
already in the first edition of his " Origin of Species " that
by this work " light would be thrown on the origin of man
and his history." He afterwards elaborated his conclusions
in the " Descent of Man," where he showed that not only
the physical features, but also the mental and moral
characteristics of man, must be regarded as the product of
a continuous progressive development from lower animals.
The precise method of the evolutionary process of man's
intellectual and moral attainments is still a matter of con-
troversy. We shall discuss these problems later, when we
deal with super-organic evolution. Here we would only
insist upon the continuity of the natural process of evolu-
tion, which is now accepted by nearly all leading scientists.
The only notable exception is A. R. Wallace, the co-
discoverer of the theory of natural selection. Whilst
attributing the perfection of the bodily structures to the
action of natural selection, he ascribes to the agency of a
spiritual worid what may be called the essentially human
faculties which distinguish man from his lower progenitors.
"A superior intelligence has guided the development of
man in a definite direction, and for a special purpose, just
as man guides the developments of many animal and
vegetable forms."*

The argument on which Wallace bases his case is, firstly,
that natural selection is unable to account for a certain

* To understand Wallace's position correctly, we must remember
that he is a spiritist believing in a hierarchy of spirits. The guiding
intelligence is, as he would have it, not necessarily a " supreme
intelligence," but may be any of the higher intelligent beings that
** people all space."

158 THE FIRST PRINCIPLES OF EVOLUTION

number of distinctly human bodily features ; and, secondly,
that there are certain higher mental endowments of civilized
man which, as they cannot possibly be due to this cause,
must have been superadded to his animal nature at an
early stage in anticipation of his future needs. The bodily
peculiarities are the feet and hands, the naked skin, the
voice and brain of man. The mental faculties alluded to are
the mathematical and metaphysical faculties, the aesthetic,
and the moral sense.

To begin with, we must point out that the inadequacy
of natural selection to account for all or any of the aforesaid
features — and this may be left as a moot point — does not
estabhsh a case for Wallace's *' spiritual influx." As to
the differentiation of foot and hand, it can be explained
as the outcome of the erect attitude of man, which latter
in its turn may well have arisen as a useful variation
through natural selection, seeing that man's next-of-kin,
the anthropoid apes, occasionally assume the semi-erect
position. The naked skin Darwin would explain as due to
sexual selection. Whether the voice of man is so much
superior to that of singing birds may be doubted. As to
the brain capacity of the savage, which is, according to
Wallace, far beyond his actual requirements, here, too, it
may be asked whether the life of the savage is really so
simple as Wallace would make out. In the use of articulate
language, of abstract ideas, etc., it decidedly goes far
beyond what any of the highest animal organisms can
attain, and the difference in brain organization may be
thus accounted for. The higher mental faculties of man,
though developed to a great degree of perfection through
the practice of thousands of years of civilization, are by no
means absent in the savage. In the first instance, they
may well have been developed, as we shall see later, through
the agency of natural selection. As to the specific endow-
ments, such as abstract conception, music, etc., it is true
they cannot be due to natural selection ; for we can hardly
assume that they had at any stage of their development

DARWINISM

159

sufficient survival value. Herbert Spencer would account
for their origin on the Lamarckian principle by the trans-
mission of the accmnulated effects of inherited mental
acquirements. But even for those who, like Wallace, do
not accept the inheritance of acquired characters, there is
still another mode of explanation at hand. There is what
has been called a " social inheritance," through which the
acquisition of one generation is handed down to the next,
be it by oral tradition or by the help of printed literature.
Thus is attained in time an ever-progressing culture
without the necessity of an actual advancement of the
mental and moral nature of civilized man. Weismann has
shown in his " Essay on Music " that the musical faculty is
latent in primitive tribes, and only needs developing by an
appropriate social environment. The same may be said
of the mathematical faculty and the artistic and moral feel-
ings of man. As F. C. Constable has put it :" At no time
are the possibilities of man's brain exhausted in achieve-
ment. Under evolution the brain capacity of the average
individual is always in advance of the practical demands
made on it."* This must be considered a natural law
of growth and development, and does not require the
prophetic prevision of a teleological cause.

(e) Degeneration.

It has become apparent from the foregoing account of
natural selection that its principles are applicable as much
to the highest as to the lowest phenomena of Hfe. There
has been a gradual progressive development of the higher
types of organisms from the simpler ones ; from the primi-
tive beginnings of the amoeba there has evolved the species
" man." But while there can be no doubt as to the correct
interpretation of this law of evolution in general, we must
guard against an error which is often made through a mis-

♦ F. C. Constable, ** Poverty and Hereditary Genius," London,
1912.

i6o THE FIRST PRINCIPLES OF EVOLUTION

understanding of the phrase "survival of the fittest,"
which is synonymous with " natural selection."

It is clear that a continuous change of environment leads
to a constant readjustment of the organisms affected.
Those best adapted to their surroundings survive, while
those unfit to meet the new contingencies are eliminated.
But it may be asked : If the survival of the fittest has led
to the transformation of the lower, more primitive forms
into the higher, more complex species, how is it that any
simple forms have survived at all ? Why did not all
species evolve ? The answer to this question is twofold :
In the first place, the terms " high " and " low " with
reference to the scale of organic beings are merely relative.
The amoeba is by no means so simple as would appear ; it
is a very complicated, highly organized piece of living
mechanism. We arrange the successive branches of the
tree of life according as we imagine them to have evolved
in the course of time, and look upon man as the highest *
offshoot of this tree. But, after all, this is a sort of anthro-
pomorphism— viewing the evolution process from a human
standpoint. Secondly, it must be weU understood that
the survival of the fittest only insures that those best
adapted to a given environment propagate and leave ofiE-
spring, while those ill-adapted succiunb in the struggle for
existence. On the whole, the continuous change and
increasing complexity of the environmental conditions
made for progress — the advent of a new species formed
each time in itself an additional complicating factor —
but wherever conditions remained stationary there arose
no need for new adaptations, and the old forms continued
their existence unchanged. The fittest, then, to survive
are by no means always the highest — the best in our sense
approaching nearest to the top of the tree of life — ^but are
those best adapted to their conditions of existence. So long
as the conditions become more complex and varied, there
results progressive organic evolution ; if they remain
stationary, the organisms, too, being well fitted to their

^
f

DARWINISM

i6i

surroundings, do not alter ; while if the conditions of life
become less complex, those organisms will have the best
chance of surviving which can adapt themselves to the new
environment by becoming themselves less complex. In
the latter case we have the phenomenon of degeneration.
Retrogression, therefore, is under certain conditions as
much a phase of evolution as progress. The term " evolu-
tion " must not be taken to cover progressive evolution
only.

We have already noted in a previous chapter that there
are organs which have become rudimentary through loss
of use and function. Now, while
there may be retrogression in one
part of the body, other parts may
be progressing at the same time, or
may be at a standstill. It is the
balance of all these opposing pro-
cesses which determines whether an
organism is to be looked upon as
degenerate or not. In order to
establish a true case of degeneracy,
the retrogressive changes must in-
volve a majority of important or-
gans. Such retrograde processes occur
in cases of parasitism, when an
animal previously leading an active
life becomes a parasite, feeding
passively on a host which supplies the sustenance ready-
made. Thus there are parasitic Crustacea which, but for
their life-histories, would be unrecognizable as belonging
to the family of crabs. The adult Sacculina is a mere
sac without legs, mouth, or intestine, absorbing nutriment
by root-like processes (Fig. 66) . Often the degeneration only
extends to one of the sexes, be it male or female. In the
parasitic crustacean Chondracanthus (Fig. 67), the male is
very much smaller than the female, and lives attached to it.
There are degenerate spiders — the mites — which infest

Fig. 66. — Sacculina.

{From " Degeneration" by Sir
E. Ray Lankester.)

■I

i62 THE FIRST PRINCIPLES OF EVOLUTION

the skin of animals (Fig. 68) . Sometimes immobility leads
to retrogressive changes, as in the Ascidians, which, accord-
ing to Professor Ray Lankester, must be looked upon as
degenerate vertebrates, which have become sessile.

Degenerate processes are not confined to morphological
structures, but may affect also intellectual and moral
traits. It is in the domain of man's mental progress that

\ Fig. 67. — Chondracanthus Gibbosus. (Magnified about 6
1 ' times.)

a Female from the side ; b, female from ventral surface, with male

(F) attached.

(From " Textbook of Zoology" by C. Claus.)

we must specially guard against confusing the " fittest '*
\with the " best." The fittest to survive may be the best,
\f the environing conditions are such as to favour the most
kighly developed individuals, physically, mentally, and
morally. On the other hand, even the worst may prove
t6 be the fittest if conditions prevail which tend to en-
courage parasitic habits of mind. It is all a question of

DARWINISM

163

■

adaptation to environment. To the full consideration of
this subject of social progress we shall return later.

B. Sexual Selection.

While natural selection is able to account for the
useful traits to be met with in the organic world, from
the lowest beings to the
highest, including man,
there is left a whole group
of characters which cannot
be explained in this man-
ner. These are the secon-
dary sexual characteristics
of the animal world.

In addition to their
distinctive sex - glands,
differentiating the male
from the female, most
animals possess further sex
distinctions characterizing
the two sexes, as size,
colour, or various struc-
tural appendages. Horns,
spurs, grasping organs,
etc., are to be found in
the male, while the special

Fig. 68. — Acarus Equi.

organs of the female <^^°^ "^'^"^"^^J^^ ^^ ^' ^"^
consist of pouches, mam-
mae, etc. Some of these special organs, as the copula-
tion apparatus of the sexes and the mammae of the female,
have direct connection with the act of pairing, or of rearing
the young, and can be explained as the result of natural
selection, since it is clear that they are essential for the
survival of the race. Selection does not imply only sur-
vival of the fittest, but also their reproduction. It is
otherwise with such features as ornamentation, the power

i64 THE FIRST PRINCIPLES OF EVOLUTION

of song, etc., which are sex characteristics of many male
animals ; and, further, with certain distmguishing traits
of the races of man, as the colour of the skin, hainness,
the form of the face, and so on. These cannot possibly
have had any survival value in the struggle for life, and
therefore cannot have been developed by natural selection.
It is for these cases that Darwin propounded his theory ot
sexual selection.

Fig. 69. — Chalcosoma Atlas.

Upper figure, male (reduced) ; lower figure, female (natural size).

{From " The Daunt of Man," by C. Darwin.)

While in the lower animals the two sexes are, on the
whole, externally not distinguishable from each other, there
often occur, as we ascend the organic ladder, the most
pronounced differences between male and female in colora-
tion and genera] appearance. We have ahready noted that
some female butterflies which mimic other species could
not possibly have been recognized as belonging to the
same species as the males had not breeding expenments

DARWINISM

165

verified their common origin. Among insects a number
of beetles can be mentioned, whose males are marked
by various horny appendages, etc. (Fig. 69). The
stridulating organs of the cricket and related species,
which produce the characteristic rasping noise, are also
confined to the male individuals only. In fishes there

Fig. 70. — Callionymus Lyra.

Upper figure, male ; lower figure, female. The lower figure is more
^^ reduced than the upper.

(From " The Descent of Man," by C. Darwin.)

is, on the whole, very httle external sex differentiation,
though a few prominent examples were given by Darwin
(Fig. 70). Among amphibians and reptiles, too, both
sexes are generally alike ; some male reptiles, however,
show various appendages, as horns, wattles, etc. (Fig. 71).
It is among birds that we find the greatest abundance of
sex differentiation, running from identical coloration m

i66 THE FIRST PRINCIPLES OF EVOLUTION

the two sexes of some species through all gradations
towards the most extreme differences, as in the case ot the
pheasant, or the bird of paradise. In other species we
find fleshy or feathery appendages or inflatmg tubes etc.,
as distinctive features of the male (see Fig. 72) ; while the
exquisite and elaborate vocal music of many songsters
is exclusively confined to the same sex. Among mammals
we generally find the males equipped with weapons, as
horns and spurs, or with manes, crests, etc.

Fig. 71. — CHAMi^LEON OWENII.

Upper figure, male ; lower figure, female.
{From " The Descent of Man," by C. Darwin.)

It is for all these secondary sex characteristics that
Darwin advanced his theory of sexual selection. While
natural selection accounts for the useful in organic nature,
sexual selection is intended to explain the beautiful. As
natural selection picks out the fittest to survive in the
battle of life, so sexual selection seizes upon the most
beautiful individuals for progapation. But while in
natural selection the celective factor Ues in the general
conditions of life leading to a struggle for existence, in

DARWINISM

167

sexual selection the choice is made by the females. It is
they who, attracted by the strongest, most prepossessing
or ornate males, mate with them, and thereby lead by a
continuous repetition of this selective process to a pro-
gressive enhancement of the selected types. That in many
cases the males enter into a contest among themselves

"^•^•V\ /IDULTM/ILE

Fig. 72. — Bell-Bird {Chasmorhynchus Nivens) (^ natural size.)

The adult male shows the ornamental appendage in inflated con-
dition ; the young male shows it in flaccid condition.

(From " Darwin and after Darwin," by G. J. Romanes,)

for the possession of the females is beyond doubt. The
battles of pugnacious birds and mammals, or even lower
down in the scale among spiders, during the love season,
are too well known to need description here. The more
peaceful combats, too, of male birds in displaying either
their highly ornamental dress or their musical powers during
the breeding season have often been described. The case

i68 THE FIRST PRINCIPLES OF EVOLUTION

of the elaborate love antics of the bower-bird, which builds
a bower and special arena covered with coloured htter, has
become classic. Now, Darwin contended that the females
exhibit an esthetic preference for the most aUunng malesr-
i.e., those that are most embellished, or most successful
in singing or fighting. He adduced various mstances,
showing that the females do not mate at random, but
often exert a deliberate choice in the selection of their
partners. Such " preferential mating " is bound to lead
to a constant improvement of the selected quaUty if the
selection is continued generation after generation. Of
course, this presupposes that the less fortunate rejected
males are unable to find a mate, and are thus altogether
excluded from propagation. For if the unsuccessful males
were not thus prevented from leaving offspnng, the next
generation could not exhibit, on the average, any improve-
ment on the last. Darwin was at pains to show that there
is in the animal world either a preponderance of males, or,
what amounts to the same thing, polygamy, which limits
the number of females available for breeding with the males.
In those cases where both sexes are highly ornamented,
the ornamentation was, according to Darwin, first evolved
in the male by sexual selection, and then transmitted
through inheritance to both sexes.

To come to the criticism of the theory of sexual selec-
tion, we may forestall our conclusion by saying at once
that, on the whole, sexual selection as proposed by Darwin
has not withstood the test of time, and stands condemned
in the opinion of most authoritative writers on evolution.
As far as the origin of the fighting apparatus of males is
concerned, the horns, spurs, etc., seeing that the law of battle
for the possession of the females often leads to the death of
the vanquished, we have in this only a specific case of
natural selection. For, as we have said, the fittest to
survive in the evolutionary sense are not those who merely
just manage to keep themselves alive, but those who
succeed in propagating their kind. Natural selection
exists for the race, and not for the individual.

DARWINISM

169

As regards the ornamental sexual characteristics, it must
be pointed out, to begin with, that they are by no means
always confined to the male sex. Darwin would account
for those cases where both sexes are highly decorated by
the transmission of sexual characteristics from the male
to the female descendants by inheritance. But what about
those instances where, contrary to the rule, the female is
the more brilliant individual ? It is not proved that m
these cases the male selects the female for her beauty.

Furthermore, the hypothesis of sexual selection pre-
supposes, as we have said, firstly, that there are a greater
number of males than females ; and, secondly, that the
rejected males should not find any mates at all. Now,
neither argmnents can be fuUy substantiated by facts.
The next point is : Do the females select their mates, and
do they do so according to an aesthetic standard ? As to
the first, it may be conceded that in some instances the
females show decided preference for certain males, but in
the majority of cases no such choice is apparent, the female
accepting the first mate that offers. But the further point
is : Are organisms so low down in the scale as butterflies
and birds capable of choosing according to an aesthetic
standard at all ? We can hardly believe that butterflies
or birds would be influenced in their choice of a mate by
a little more or a little less colour. Lloyd Morgan, in order
to save the theory, argues that the female does not exert
a conscious choice, but is incited to pair with the male
who, by his display and adornment, calls forth the greatest
sexual emotion in her. But if this is so, would a sUght
variation in brightness or colour make all the difference
whether a male were accepted or not, as we must believe
according to Darwin's theory ? Finally, it has been shown
definitely by experiments on certain butterflies that the
females mate indiscriminately with all males, whether they
have their own brilliant wings, false coloured wings, or no
wings at all. The mating most probably takes place by
chemotaxis^-t.^., by the attraction due to substances

I70 THE FIRST PRINCIPLES OF EVOLUTION

exhaled by the body. In the case of birds it has been
shown that their colour sense must be different from ours,
and we cannot therefore judge their aesthetic standard, if
it exists, by our own. Lastly, if the females did effect a
deliberate or unconscious choice according to an aesthetic
standard, we should have to posit a different taste in the
females of aUied species, and this often to an immense
degree— more than can conveniently be brought under the

law of variation.

What purpose, then, have the display and the love
antics of the males during the mating season, if they are
not intended for sexual selection ? The answer to this is :
A general heightening of briUiancy and excitement dunng
the breeding season occurs among male animals, as low in
the scale as fish, or even worms. As no pairing takes
place among these creatures, the change cannot be ex-
clusively referred to sexual selection.

What, then, is the alternative explanation of the
secondary sex characteristics ? Sex colouration is a fact,
and has to be accounted for. A. R. Wallace, who pms
his faith to natural selection, attributes the diversity
of colour in aUied species to the need of recognition among
the members of the same species. The song of birds, too,
must, according to him, be looked upon as a recognition
call between the two sexes. As for the differentiation of
colour between the male and female, the dull tints of the
female are the result of protective colouration, produced
by natural selection on account of the female's greater need
of protection, since upon her the task of breeding and
rearing the young generally devolves. The briUiancy of
the males is due to their greater vigour, the surplus of vital
energy manifesting itself not only in more pronounced and
vivid pigmentation, but also in the growth of tufts, acces-
sory plumes, etc. These are apt to appear, as A. Taylor
has shown, at certain definite lines of the body, just hke
the primitive ornamental spots in animals, which later
flow together into bands and blotches.

DARWINISM

171

The argument against Wallace's theory is short. First
of all, the fact that the females remain protectively coloured
through the action of natural selection does not go against
the contention that the brilliancy of the males is attained
by sexual selection, where no such reason mitigates against
it. Secondly, even granted that the more intense colour
of the male in general may be explained by excess of vigour,
this would not account for the origin of the gorgeous and
elaborate patterns of the males, nor for the development
of the excessive ornamental appendages of some birds,
which would seem a positive hindrance to them.

As a final argument against sexual selection, Wallace
advances the following : Seeing that natural selection is
constantly weeding out harmful traits, it is not conceivable
that the elaboration of mere beautiful characteristics by
means of sexual selection should not have been checked
by it. " The extremely rigid action of natural selection
must render any attempt to select mere ornament utterly
nugatory, unless the most ornamental always coincide
with the fittest in every other respect ; while if they do
so coincide, then any selection of ornament is altogether
superfluous." But Lloyd Morgan points out, as already
indicated above, that preferential mating and natural
selection are by no means incompatible with each other.
" The two processes begin at different ends of the scale of
efficiency. Natural selection begins by eliminating the
weakest, and so works up the scale from its lower end until
none but the fittest survive ; sexual selection, by prefer-
ential mating, begins by selecting the most successful in
stimulating the pairing instinct, and so works down the
scale until none but the hopelessly unattractive remain
unmated."

Other theories of secondary sex characters have been
proposed, but do not cover a wide enough range of pheno-
nomena to have met with general acceptance. None has
been able to take the place of sexual selection propounded
by Darwin. As Professor L. Plate sums up his defence of the

172 THE FIRST PRINCIPLES OF EVOLUTION

theory of sexual selection : " It is better than any other
hypothesis advanced so far, and has to serve us imtil a
more adequate one is found."

4. DIFFICULTIES OF THE THEORIES

We have so far examined the theories of Lamarckism
and Darwinism separately in their historical sequence. But
in order fully to understand their import, we must con-
sider them in their mutual relationship. Not only do these
two theories form the main armoury of the present-day
evolutionists, but the question of the origin of species has
of late largely resolved itself into a discussion of the respec-
tive merits of the two rival systems. For though Darwin
devised his theory of natural selection mainly to replace
that of Lamarckism, he by no means disdained to avail
himself of Lamarckian principles. He fully acknowledged
the effects of the environmental factors, and relied upon
them in many cases where they appeared to afford a better
solution of the problem under consideration. It is other-
wise with Wallace, the co-discoverer of the theory of
natural selection. He would reject not only the Lamarck-
ian principle, but also sexual selection, or any other acces-
sory theory of evolution. For him natural selection is the
only true, the only possible factor in the progressive de-
velopment of species.* This ultra-Darwinian standpoint
has of late come very much to the front through the labours
of Professor A. Weismann, a German scientist. He, with
many adherents, forming the Neo-Darwinian school, main-
tains the " all-sufiiciency " of natural selection, and is in
entire opposition to the modern upholders of the Lamarckian
theory, the Neo-Lamarckians, who, on the other side,

* But he rejects natural selection as an effective factor in the
evolution of the higher faculties of man, which he attributes to
spiritual agencies. We see from this how little justification there
is in the title of his book on evolution, which he calls "Darwinism.**

DARWINISM

^73

discard natural selection altogether, or aUow it at best
merely a secondary role in the scheme of evolution.

The difficulties of either of these extreme schools are
very great indeed when taken singly, each side being able
to make out an apparently strong case against the other.
Before entering, however, into a detailed discussion of the
arguments for or against either school, we must for clear-
ness' sake once more emphasize the main difference between
the two contending theories. In both theories, Lamarck's
as well as Danvin's, the environment plays an important
role. But we must note a fundamental distinction in the
way the surroundings act in each case. According to the
Lamarckian theory, the environmental factors have a
direct effect on the individuals subject to their influence.
The individual adapts itself to the new conditions, and
becomes modified accordingly. It is the environment
which directly transforms the individual, each generation
handing down in succession the newly acquired characters
to their offspring. Thus a gradual transformation of the
whole species takes place in agreement with the environ-
ment. It is otherwise with natural selection. Here, too,
a change of organisms takes place, when new environmental
conditions arise. But in this case the environment does
not mould the individual directly into fitness with new
conditions of life, but acts, as it were, like a sieve, allowing
those only to survive who are from the beginning adapt-
able to the new circumstances, while those not adaptable
die out. Thus the standard of the surviving individuals
is constantly raised by the progressive selective action
of the environment. Fig. "/^ represents the difference
very neatly in a graphical manner. In A the Lamarck-
ian effect of the environment transforms all (or nearly
all) individuals in accordance with the new conditions
(which are supposed to lead to an elongation of form).
In B, where the action of natural selection is illus-
trated, the environment will only let pass through the
more or less elongated forms, of which, in accordance with

172 THE FIRST PRINCIPLES OF EVOLUTION

theory of sexual selection : " It is better than any other
hypothesis advanced so far, and has to serve us mitil a
more adequate one is found."

4. DIFFICULTIES OF THE THEORIES

We have so far examined the theories of Lamarckism
and Darwinism separately in their historical sequence. But
in order fully to understand their import, we must con-
sider them in their mutual relationship. Not only do these
two theories form the main armoury of the present-day
evolutionists, but the question of the origin of species has
of late largely resolved itself into a discussion of the respec-
tive merits of the two rival systems. For though Darwin
devised his theory of natural selection mainly to replace
that of Lamarckism, he by no means disdained to avail
himself of Lamarckian principles. He fully acknowledged
the effects of the environmental factors, and relied upon
them in many cases where they appeared to afford a better
solution of the problem under consideration. It is other-
wise with Wallace, the co-discoverer of the theory of
natural selection. He would reject not only the Lamarck-
ian principle, but also sexual selection, or any other acces-
sory theory of evolution. For him natural selection is the
only true, the only possible factor in the progressive de-
velopment of species.* This ultra-Darwinian standpoint
has of late come very much to the front through the labours
of Professor A. Weismann, a German scientist. He, with
many adherents, forming the Neo-Darwinian school, main-
tains the " all-sufiiciency *' of natural selection, and is in
entire opposition to the modern upholders of the Lamarckian
theory, the Neo-Lamarckians, who, on the other side,

DARWINISM

173

discard natural selection altogether, or allow it at best
merely a secondary role in the scheme of evolution.

The difficulties of either of these extreme schools are
very great indeed when taken singly, each side being able
to make out an apparently strong case against the other.
Before entering, however, into a detailed discussion of the
arguments for or against either school, we must for clear-
ness* sake once more emphasize the main difference between
the two contending theories. In both theories, Lamarck's
as well as Darwin's, the environment plays an important
role. But we must note a fundamentad distinction in the
way the surroundings act in each case. According to the
Lamarckian theory, the environmental factors have a
direct effect on the individuals subject to their influence.
The individual adapts itself to the new conditions, and
becomes modified accordingly. It is the environment
which directly transforms the individual, each generation
handing down in succession the newly acquired characters
to their offspring. Thus a gradual transformation of the
whole species takes place in agreement with the environ-
ment. It is otherwise with natural selection. Here, too,
a change of organisms takes place, when new environmental
conditions arise. But in this case the environment does
not mould the individual directly into fitness with new
conditions of life, but acts, as it were, like a sieve, allowing
those only to survive who are from the beginning adapt-
able to the new circumstances, while those not adaptable
die out. Thus the standard of the surviving individuals
is constantly raised by the progressive selective action
of the environment. Fig. 73 represents the difference
very neatly in a graphical manner. In A the Lamarck-
ian effect of the environment transforms all (or nearly
all) individuals in accordance with the new conditions
(which are supposed to lead to an elongation of form).
In B, where the action of natural selection is illus-
trated, the environment will only let pass through the
more or less elongated forms, of which, in accordance with

174 THE FIRST PRINCIPLES OF EVOLUTION

the law of variation, there will always be a certain number
among the mass of individuals. According to Lamarckian
interpretation, the change affecting the individuals is
directly induced by the environment, and is transmitted
to the next generation. According to the Darwinian
theory, the variations are given primarily ; natural selection

Fig. yi. — Diagram to illustrate — A, The Transmission of Ac-
quired Characters ; B, Modification of Type by Natural
Selection.

In A an organism, represented by the circle, has offspring. The
environment is represented by a board with holes through
which they must pass. In so doing they become elongated,
transmit the elongated form to their progeny, and so on. In
B a rounded organism has progeny which vary. One cannot
pass through the board and is eliminated ; the other, being
somewhat elongated, can pass and has progeny, which again
vary in a similar manner, the more elongated type being
selected each time.

{From " Darwinism and Race Progress," by J. B. Haycraft.)

merely ensures the survival of the types best fitted to the
environment, while the unfit are weeded out and disappear.

How far can either theory be upheld as an independent
system — i.e., as a principle sufficient in itself to bring about
the progressive evolution of species ?

We shall first discuss the difficulties of Neo-Lamarckism,
and then those of Neo-Darwinism.

NEO-LAMARCKISM

A. Neo-Lamarckism.

175

We have seen that, according to Lamarck, two modes of
action of the environment can be distinguished. The one
consists in the direct influence of external conditions,
climate, food, etc. ; in the other the effect is more mediate
through the functional use or disuse of active organs. In
both instances the effects wrought on the individual are
supposed to be inherited by successive generations. Neo-
Lamarckians may accordingly be divided into two camps —
the botanists, who mainly insist on the first factor of
Lamarckism, and the palaeontologists, chiefly of America,
who, led by their studies of extinct types of animals, look
upon the inherited effect of use and disuse (use-inheritance)
as the important element in the progressive development
of species.

We have, then, to decide the following double question :
Can Lamarckism in either form, whether singly or combined,
account for the evolution of species ? Is the inheritance
of acquired characters an accepted fact of science ? In
order to develop the argument more clearly, we shall posit
— ^what has still to be proved — that the latter question
has been answered in the affirmative. For without it
Lamarckism would be deprived of its basal assumption.

Now, as to the first case, that of passive acquirements,
the difficulty arises : How is it that the organism reacts
in a definite manner to a constantly varying change of con-
ditions, so that useful improvements of orga.ns arise
and accumulate in certdn given lines ? How can we
imagine, for instance, that the complicated modifications
of the limbs of certain articulata, the stridulating organs
of the locusts, or the " brush and comb " apparatus of the
bee (Fig. 74), have been developed in this manner, seeing
that they are made of im5delding chitin ? The mutual
adaptation of the different parts is too complex to have
been brought about by the environmental stimulus ; while
the principle of use-inheritance is excluded in the case of

t 1

176 THE FIRST PRINCIPLES OF EVOLUTION

such passive structures. Or, to take another example:
How can passive adaptation explain the change of an edible
butterfly so that it mimics an inedible species ? At best
it may, perhaps, be admitted with Plate that indifferent

Fig. 74. — Brush and Comb on the Leg of a Bee (Nomad a).

Hb End of tibia ; i^, first tarsal joint with the brush and its comb
{tak). Between these and the tibial spine {tisp) , with its lappet
(L), the cross-section of an antenna {At) is indicated.

{From " Tlu EvotutUm Theory," by A. Weismann.)

qualities may thus be imposed upon the organism from
without, or very occasionally simple useful characteristics,
if the environmental conditions affect a mass of individuals
persistently for a long time. But here the question at
once arises : Are such changes inherited ?

NEO-LAMARCKISM

177

To many biologists Lamarckism is mainly represented
by the principles of functional adaptation. Their argu-
mentsr-as, e.g., those of Weismann-— are mainly directed
against this side of the Lamarckian system. It is clear, of
course, that passive adaptations cannot at all be accounted
for in this way. But even active adaptations can by no
means always be explained by the inherited effects of use
and disuse. How should, for instance, mere use convert
the harmless gland of a snake into a poisonous weapon ?
How could the effect of use alone elongate the fangs of
the Babirussa, seeing that they first have to pierce the
skin, when they would be completely useless ? Further-
more, when instincts are explained by this school as in-
herited habits— that is, as due to the constant repetition
of acts which are transmitted to the offspring— what have
we to say about those instincts which are performed only
once in the hfetime of the individual ? Here there can be
no question of the inheritance of persistent efforts. Or, to
take the case of the neuter bees, they cannot possibly
transmit their functions to the next generation, for they

are sterile.

But the chief point still remains : What proof have we
that characters acquired during the lifetime of the parents
are transmitted to their progeny, and thereby accuniu-
lated ? It is quite true that the muscles of the blacksmith
become strengthened by constant use ; but what evidence
have we that this improvement is eo ipso inhented by his
children ? Lamarck himself simply took the inheritance
of acquired characters for granted, and so did most of
his followers, until Weismann showed that there was by
no means so favourable a case for it as has generally been
assumed. It would be far too lengthy a task to enter here
into a detailed discussion of the problem of the inhentance
of acquired characters. This is a question of heredity,
and is dealt with in the appropriate textbooks.* We would

• See the author's " The First Principles of Heredity " (A. and
C. Black). 23

178 THE FIRST PRINCIPLES OF EVOLUTION

merely point out that Weismann distinguishes sharply
between the body of the individual and the germ-cells
which form the stock of the next generation. His view,
now largely accepted, is that the qualities superimposed
upon the body of the individual by external conditions
do not generally affect the germ-ceUs at the same time
and in the same manner. The newly acquired qualities
cannot therefore be transmitted to the next generation.
All arguments in favour of such occurrence can be shown
to be either fallacious or not unequivocal. In any case,
even if admitted as possible, it must be considered too rare
a contingency to be reckoned with as a constant factor
in the elaboration of new characters. It follows from this
that any theory of evolution based upon this factor, such
as is the theory of Lamarckism, must be discounted so
long as it fails to establish its first premise— the inheritance
of acquired characters.

B. Neo-Darwinism.

We have already noticed that there are two schools of
Darwinists. The first is represented by Charles Darwin
himself and his defenders, Romanes, Plate, etc., who, whilst
looking upon natural selection as the main factor of evolu-
tion, still do not believe it to be the only factor. To them
the environmental effects of external conditions, including
use-inheritance, are accessory means of species formation.
The other school, starting with Wallace and headed now by
Weismann, maintains the " all-sufhciency " of natural
selection, beUeving it to be the only true cause of the origin
of species.* The criticism against Darwinism divides itself
into two parts, according as we have to argue against
natural selection in general, or whether we have to deal
with the extreme selectionists, who do not admit any other

♦ Weismann himself admits, however, the validity of sexual
selection!

NEO-DARWINISM

179

species-forming principle. Among the critics of natural
selection we find some authors who go so far as to refuse
to accord it any value whatsoever in the scheme of evolu-
tion ; others have advanced grave difficulties, which apply
specially to the narrower principle of Neo-Darwinism. We
can here only give a very brief summary of some of the
more important objections.

As to the general arguments against natural selection,
the first in order is perhaps the contention made by some
that natural selection does not, as a matter of fact, exist
in nature. There is, in any case, so it has been said, no
positive evidence for it. Now, it must be admitted that
it is practically impossible to trace by direct observation
any special case of selection in nature, as the conditions
are generally too complex to be sifted with scientific cor-
rectness. Still, some experimental observations have been
made which go far to show that adaptations, as interpreted
by the selectionists, have a life-serving value. Thus
Cesnola fixed specimens of the brown and green varieties
of Mantis religiosa on plants, and found that the individuals
tied to plants of a harmonious colour escaped death ; while
the others, being conspicuous through their colour con-
trast with the plant, were mostly devoured. Poulton and
Sanders made similar experiments with the pupae of a
butterfly {Vanessa urticce) and had similar results. This
tends to show that protective colouration is a real survival
factor, giving a decided advantage to its possessors in the
struggle for existence. But, on the whole, the principle
of natural selection is, as Professor Lloyd Morgan has
insisted, " more a logical conclusion than a matter of
direct observation." We know that there is an over-
production of organisms ; we know that only a certain
number of them can and, as a matter of fact, do survive ;
it follows, therefore, that selection must take place accord-
ing to some underlying law. According to the theory of
Darwin, this determining principle lies in the adaptation
of the individual to the environment, which leads, as

i8o THE FIRST PRINCIPLES OF EVOLUTION

Herbert Spencer has expressed it, to " the survival of

the fittest."

Taken for granted that natural selection acts m the
manner indicated, it still does not explain— so runs the
next argument against Darwinism— the origin of species.
Starting with the given qualities of the individual, and
accepting the pre-existence of variations, it simply rears
upon these as a basis the superstructure of organic evolu-
tion. AU that natural selection does is to determine by
a process of elimination which are to survive to form the
next generation. " It may," as it has been tersely put,
" explain the survival of the fittest, but cannot explain
the arrival of the fittest." Whence the variations ? It
is clear that Lamarckism accounts for new characteristics
in its own manner, explaining them as the direct result
of the action of the environment upon the individual.
Darwin himself fully recognized this dependence of natural
selection on " what we in our ignorance call spontaneous
or accidental variabihty." Since his pioneer work on the
subject of variation, a great deal of research has been done
in this branch of inquiry, to which we shall return later.
But while thus variabihty forms the starting-point of the
process, it does not follow, as some antagonists would have
it, that " selection acts only negatively." It is true it
does not produce the variations ; but it directs them into
certain lines, accumulates them in successive generations,
and thereby originates new biological characters out of
indefinite beginnings. It certainly creates species from
out a mass of fluctuating varieties.

We now come to the other series of criticisms, which, as
we shall find, possess a good deal of validity when directed
against the extreme standpoint of Weismann's school,
Darwin and his strict followers do not hesitate to make
use of other factors of species formation, whenever the
principle of natural selection seems insufficient for a solu-
tion. It is otherwise with the school of Neo-Darwinists.
They try to explain all organic evolution by natural selec-

NEO-DARWINISM

i8i

•1

tion, and natural selection only ; and, as we shall see
presently, they have therefore been put to considerable
straits in order to uphold their position against the vehe-
ment attacks of friend and foe ahke.

It follows from the extreme view taken up by the Neo-
Darwinians with regard to the exclusiveness of natural
selection as a means of species formation, that all specific
characters--i.e., those by which we distinguish one species
from another— must be useful. For natural selection only
fosters useful characteristics, and all species which have
survived by virtue of their adaptations must be distinguish-
able by these very adaptive traits. As the case has been
put by Wallace in an extreme way : " It is a necessary
deduction from the theory of natural selection, that none
of the definite facts of organic nature— no special organ,
no characteristic form or marking, no pecuHarities of
instinct or of habit, no relations between species or between
groups of species— can exist, but which must now be, or
once have been, useful to the individuals or the races which
possess them." Now, first of all, does the theory of natural
selection imply of necessity any such logical deduction ?
Secondly, is it a fact that all specific characters owe their
origin exclusively to their usefulness? As to the first
contention, Romanes has shown to the full that the con-
clusion drawn by Wallace is only valid if we do not admit
any other evolutionary principle besides natural selection.
As to the second point, there are innumerable specific
characteristics to which no possible use can be assigned,
either in the present or past condition of their existence.
It is true many traits have been explained on utilitarian
principles which previously appeared quite valueless.
Still, there are a great many others for which the plea of
ignorance cannot be raised. The trivial colour distinctions
to be found between many different species of birds,
mammals, etc., can certainly not be reckoned of any
selective value whatever.

Of course, the strict followers of Darwin are not logically

*^\

i82 THE FIRST PRINCIPLES OF EVOLUTION

forced to deny the existence of unadaptive specific char-
acters. According to them, any cause acting uniformly
during a long series of generations on many individuals
would probably produce a constant modification. The
ultra-Darwinists, on the other hand, who are ready to go
so far as to admit the occurrence of such useless indifferent
features, can only faU back on the assumption that aU
such characters came into existence together with and
dependent upon other useful traits.

A similar, but much more relevant, objection advanced
against Darwinism concerns the first beginnings of adapta-
tions. "Natural selection,*' according to this view, 'is
incomoetent to account for the incipient stages of useful
structures." According to the Darwinian theory, the
progressive elaboration of organs takes place by the accumu-
lation of slight variations through small successive steps.
These variations have been called " fluctuating," " con-
tinuous," or " individual " variations ; for they fluctuate
around an average or mean, and can be arranged m a con-
tinuous series. Now, the principle of natural selection
implies that any such variations can only be preserved
and seized upon for further development if they have
survival value— that is, if they are of sufficient value to be
a determining factor in the struggle for Hfe— otherwise
natural selection has no hold on them. The question now
arises : How much fitness is sufficient to lead to survival ?
Can the small differences which constitute, according to
Darwin, the material of organic evolution, be of sufficient
value to decide in a given case between the life and death
of an individual ?

Now, there cannot be any doubt that we have here a
weighty objection— one that cuts at the very root of the
theory of natural selection. Darwin was fully aware of
its seriousness, and he and his followers have tried to over-
come this obstacle by various accessory explanations.

In the first instance, as Plate pointed out, there are a
number of contingencies where even slight differences may

NEO-DARWINISM

183

be of vital importance in times of stress and danger ; for
?t is evTdent that it is chiefly at such periods that selection
does Us work, and does it most stringently Secondly we
must keep clearly in mind the fact, emphasized by J. L.
Tavlor that " the whole and not merely a part of the
organi;m is selected, and therefore each variatk)n does not
require to be of the same value, as if selection depended on
it alone " In addition, various other auxihary factors
hav been adduced towards a solution of this probkm
For those, Uke Darwin himself, who admit Lamarckian
principles the external conditions furnish a Potent means
for initiating new variations, which are handed down by
inheritance, until they can be taken fvan^^^^^^^^^
natural selection. On the other hand, the anti-Lam-
arckians, who do not admit the inhentance of acqmred
characters have availed themselves of a similar argument.
bSu iid Osborn in America, and Lloyd Morgan m
England, have propounded a theory which has yanously
beel caied " organic selection," ;; orthoplasy onto-
genetic " or " coincident selection." On this theory, the
individually acquired characters, though not transmi ted
to the offspring, serve to tide the successive gene^^^^^^^
over the critical period until germinal (inborn) variations
Sesamekindarpearwhichareinheritable Ontogenetic
(individuaUy acquired) adaptations and natural selection
work together towards the same end. ^.,^;^n<;

Of other factors involved in the making of adaptations
we mention the laws of growth, correlation, change of
environment and of function. Darwin has given a
beautiful example of the first. The sutures m the slams
of young mammals, which would seem to be an adaptat on
for aiding parturition, have most probably arisen m the
first instance by inherent laws of growth, for they occur n
the skulls of young birds and reptiles, which only have to
break through an eggshell at birth. Or f^^'f^^^^^^
originate in the first instance as useless characters m cor-
relation with other useful traits. It is well known that

i84 THE FIRST PRINCIPLES OF EVOLUTION

there exists a certain relationship between the different
parts of an organism, so that a change in one part goes
together with change in the other. All such indifferent
traits may suddenly acquire survival value when new
contingencies arise. There may occur either a change of
environment which brings into prominence a feature up
to then of no special importance, or an alteration of
function may take place in the organ due to changed con-
ditions of life. The organ developed by natural selection
for one purpose assumes a new function, thus starting at
an initial stage of usefulness which it could not have
acquired through its new function alone. Thus it is hard
to understand how the primitive stages of lungs could
have been of any value— least of all of vital value— to the
first air-breathing animals. But the fact is that the lungs
are nothing but the swimming bladder of the fish con-
verted into a breathing apparatus (Fig. 75).

Though all three explanations together would account
for a great number of cases, it is evident that they are
hardly able to cover the whole ground of possible adapta-
tions. Seeing that, according to natural selection, all the
initial stages in the evolution of useful characters must
have survival value, this problem presents one of the
greatest difficulties of Darwinism, especially for the ex-
treme Neo-Darwinists who cannot fall back on Lamarckian
principles. In fact, Weismann, in order to free the theory
of natural selection from this fundamental defect, has
devised a subsidiary hypothesis— that of germinal selec-
tion—which is intended to explain not only the beginnings
of adaptations, but also their disappearance, the possi-
bility of correlation, etc., from the exclusive standpoint of
selection. This theory we shall discuss later in detail.

Finally, we must mention the opinion of De Vries and
his school, who deny altogether the efficacy of the small
Darwinian variations as an effective means of evolution.
Organic evolution, on this view, does not take place by
means of small continuous steps, but rather in a saltatory

NEO-DARWINISM

185

way each successive stage forming a definite measurable
variation from the previous one. These discontinuous
variations, or, as they have been called by De Vnes, mu-
tations " furnish the sole material for the action of natural

Fig. 75.— Evolution of Lungs from Swim-Bladder of Fish.

, K..1 2 Mud-fish (Ceratodus)\ swim-bladder used during the dry season as a
breathine organ V MeHobranckus, with gills and lungs, equally at home .n wa^er
,n^ on Und ^ Siren the same a^ previous stage, but lungs more developed.
Tand 6 Newt*;ndbVog.^th possessing gills onlv in Uie tadpole stage, but losing
?hem in the a^uriung-lireathin"^ stage. C. gilfs; (ES.. oesophagus or gullet .
S.Bl., swim-bladder; i^., lung.

/„ each illustration the integument is shown to be partly removed in order to exhtbtt the

inner organs.

selection. As each step involves a sudden advance, this
theory is freed to a considerable extent from the difficulty
besetting the original theory of Darwin.

Similar considerations, as just discussed with regard to
the beginnings of adaptations, apply with equal force to
the problem of their degeneration and disappearance. We

i86 THE FIRST PRINCIPLES OF EVOLUTION

have seen that organs which cease to be useful become
atrophied. How can this process be accounted for ? The
old Darwinists relied mainly on Lamarckian factors as an
explanation. The disuse of an organ leads to its diminu-
tion, which, if inherited in successive generations, must
effect its gradual reduction and final disappearance. Ad-
verse environmental conditions, too, may similarly bring
about retrogression. Much weight was formerly laid on
a saving of nourishment which would be beneficial to those
individuals least encumbered with useless organs. But
it is hardly conceivable how an ounce of substance more or
less could mean anything, say, to a whale, whose hind-
legs have been dwindHng for ages. There remained only
one strictly Darwinian interpretation of rudimentary
organs — namely, reversed selection. If an organ becomes
positively harmful through its size, natural selection will
weed out those individuals which possess the disadvan-
tageous structure in the greatest degree, and will thus lead
to its gradual reduction and elimination. The wingless
beetles on wind-swept islands are a case in point. It must,
however, be admitted that instances of reversed selection are
rare on the whole, and cannot therefore solve the problem.
Romanes first tried to devise a satisfactory answer on
strict Darwinian lines. If natural selection is necessary
in order to evolve an organ, it follows, so he reasoned, that
the organ can only be sustained on its attained level by
the same force. As soon as natural selection ceases to
act— and this must happen whenever an organ becomes
useless — retrogression must set in. This theory of the
" cessation of natural selection " was later on more elabor-
ated by Weismann, who gave it the name of " panmixia "
—i.e., an indiscriminate mating of all without regard to
the quality of their traits. This would lead to a general
levelling down of the whole stock. We shall discuss the
value of this theory later, but must remark here that
Weismann himself found reason later on to supplement
this theory by that of germinal selection. Just as ger-

NEO-DARWINISM

187

/ \

minal selection enhances, on the one hand. Jhe tenden^^^ oi
characters once directed along the lm> ^^ f ^J'^'if^^^^
in the same manner, as soon as dechne sets m, germing
selection will accelerate this process, and ultimately lead
to a complete elimination of the useless character. We
shall deal later on with germinal selection as a whole.

A further important argument against natural selecUon
is the following: How is it that the required yanations
always appear It the right time for natural selection to act
upon! anyhow especially can we reckon upon a coincidence
of a multiphcity of useful, mutuaUy interdependent char
acters, which go to make up complex «'^g^"^°'^ P^'*!,; 'F''^
selection of the fittest, it has been said, is too much a

matter of chance. . j u* t-u^t the.

Now, as to the first question, there is no doubt that the
useful variations often do not occur, in which case the
organic forms, not being adaptable to the new circum-
stances simply die out. '• Selection follows variation
not variatiT selection." It is therefore a misstatemen
of the problem to ask why the necessary vanations are
always at hand for selection ; often they are not, but
when they are present, natural selection can act upon
them. That the right variations do occur so frequently
is due to the fact, which Plate has demonstrated that
with a given change of conditions, more than one line of
progressive adaptation is possible. An animal in time
oi danger may escape its enemy either by being swifter
being more wary, or more ferocious, etc. Any one of
S t'aits may'lead to its -rvival the characten^^^^^^^
of the different individuals being combined later through
intercrossing into a mixed type. The '^semblance of the
leaf-butterfly to leaves must have been brought about m
this manner by the gradual accumulation of different

structural points. *„+;„„<: it

As to the second question-that of co-adaptations-it

has been the battle-ground between Neo-Lamarctaans and

Neo-Darwinians for a long time, without either party

i88 THE FIRST PRINCIPLES OF EVOLUTION

gaining a decisive victory (see especially the controversy
between Spencer and Weismann). It is evident that if,
under the influence of new conditions, one part of an
organ or organism is changed, the whole vital economy of
the individual would be disturbed, unless the other parts,
closely connected with the varying part, also changed con-
currently and in harmony with it. Thus, to take Herbert
Spencer's illustration: As the antlers of the giant stag
gradually increased in size, it was absolutely essential
that the skull should become proportionately thicker,
and the neck and forelegs stronger, in order to support the
increased weight. To Spencer and the Lamarckian school
this question seemed to afford sufficient evidence in favour
of the Lamarckian principle of use-inheritance. For it is
clear that on this hypothesis co-adaptive changes find an
easy explanation. The correlated parts change together
simply because they are subject to the same influence of the
inherited effects of use. Passive adaptations, however, can-
not thus be accounted for ; and, further, in any case, use-in-
heritance is still unproven. Other explanatory factors, then,
from the selectionist point of view have to be considered.

There is, first of all, the principle of simultaneous cor-
relative variability, according to which organs functioning
together have the tendency to vary in the same general
direction. The elongation of the bone of an arm or leg
is accompanied by a lengthening of the attached muscles,
as also of the supplying bloodvessels and nerves. Secondly,
the^fact must not be overlooked that in many instances
harmonious changes of complex adaptations do not need
to occur simultaneously, but may follow each other, as, for
instance, in the case of mimicry. Thirdly, according to the
principle of coincident selection already mentioned, indi-
vidually acquired modifications would be able to take the
place of the appropriate necessary adaptations until these
arose by germinal variation. Thus, while the antlers of
the elk increased by spontaneous variation, the support
necessary for the additional weight could be supplied

NEO-DARWINISM

189

temporarily by the increased strength of each given indi-
vidual. Finally, Weismann has used his theory of ger-
minal selection as a possible explanation of co-adaptive
structures.

We come now to our last argiunent against Darwinism,
which amounts to this : Natural selection can only effect a
progressive change of any given species, but is unable
to break up the species into several distinct types. Or, to
express it in the words of Romanes : Natural selection
produces monotypic, but not polytypic — i.e., divergent
evolution. Swamping by intercrossing is the great obstacle
to the effective action of natural selection. For it is clear
that, unless the new-arising varieties are kept separate
from the old stock and from each other by some means,
intercrossing will sooner or later lead to a levelling down of
the whole stock, and make nugatory every attempt at
creating new and distinct types. Furthermore, it is
difficult to see how, without isolation, a minority of a new
adaptive type can be turned into a majority.

As regards the latter point, Delboeuf has calculated
mathematically that the number of a given new variety
is bound to increase up to and above the number of the
non-varying type, thus replacing it gradually. But
Plate, thoroughgoing Darwinist though he is, does not see
his way to accept this law. He admits, however, the
accumiilating effects of Mendelian inheritance, and has
tried to show that a new type must gradually become pre-
eminent, if it happens to be distinguished from the old
one by a positive character, which generally is dominant
in the Mendelian sense.*

* In Mendelian inheritance the cross between two parents
shows the characteristics of the " dominant " parent, the traits of
the other parent being " recessive " — i.e., externally not visible.
The hybrids mating among themselves give offspring, of whom
75 per cent, are dominants and 25 per cent, recessives. Of the
75 per cent, dominants, 25 per cent, on further inbreeding are found
to be pure dominants — i.e., they breed true indefinitely, while the
25 per cent, recessives all breed true. It is clear, therefore, that on

190 THE FIRST PRINCIPLES OF EVOLUTION

For the Mutationists the question of intercrossing is
much less urgent ; for mutations are new varieties fully
formed, capable of holding their own from the very be-
ginning, and therefore less liable to be swamped. To the
Darwinist, however, the difficulty of intercrossing is very
real indeed. Darwin himself hardly realized to the full the
seriousness of this objection, and his defence of natural
selection on this point is certainly not effective. His fol-
lowers—Romanes, Plate, and others— have fully ad-
mitted the inadequacy of natural selection to account for
evolution in divergent lines. Some form of isolation is
now generally assumed as a necessary adjunct to the Dar-
winian theory. To this subject we shall address ourselves
at the end of this chapter.

Auxiliary Theories of Natural Selection.

It has become clear, from the foregoing survey of the
respective merits of Lamarckism and Darwinism, that
neither theory is by itself capable of giving a satisfactory
explanation of the process of organic evolution. La-
marcMsm suffers from a fundamental weakness, in that its
very basis — the inheritance of acquired characters — has
so far not been substantiated by scientific facts. On the
other hand, Darwinism, especially as expounded by the
Neo-Darwinists, fails, as we have seen, in many points of
importance. It is for this very reason that a number of
auxiliary hypotheses have been devised in aid of natural
selection; while Weismann, by his special theories of
panmixia and germinal selection, endeavoured so to

mating two separate Mendelian strains, though the hybrid combines
both parental characters (one visible, the other hidden), in the suc-
ceeding generation both strains breed out separately. As there are
always more dominant offspring than recessive, it will be seen that
a newly appearing dominant character must gradually outnumber
any given recessive character For further details see the textbooks
on heredity.

NEO-DARWINISM

191

^>i

strengthen the Neo-Darwinian position as effectively to
dispense with any Lamarckian taint of it. We shall
discuss the latter two theories, in addition to those of
intra-selection, coincident selection, and isolation.

{a) Panmixia.

Cessation of selection as a cause of atrophy was first
proposed by Romanes. Later on, Weismann, whilst ex-
amining the validity of the principle of use-inheritance,
adopted the same idea, called by him " panmixia," in order
to account for the dwindhng and disappearance of useless
organs without having recourse to the Lamarckian
factors. If natural selection leads to the mating of select
types, so that those below a certain standard are prevented
from propagating, it follows that, with the cessation of
selection, a general crossing of all types, including the in-
ferior ones, must take place, and thus lower the average
quahty of the whole stock. Weismann explained in this
manner, for instance, the prevalence of short-sightedness
among civilized people. The individuals with defective
eyesight not being weeded out in modern society, the
sharpness of the eyesight of the population sinks gradually.
The same would apply to the deterioration of the teeth of
man, of the breast-gland of modern women, etc. The
fact that degeneration generally progresses so slowly,
often taking thousands and thousands of years, seemed
to him a sufficient proof of the inadequacy of the La-
marckian explanation. For if the effect of disuse were
transmitted in accmnulating ratio in the successive genera-
tions, a useless organ ought to disappear much more quickly,

Weismann originally attributed a great effect to pan-
mixia, and considered that nearly 90 per cent, of the reduc-
tion of rudimentary organs was due to it ; the remainder,
up to the complete loss of the organs, being accounted for
by reversed selection. Romanes was much more modest
in his estimate, and only allowed about 10 to 20 per cent.

192 THE FIRST PRINCIPLES OF EVOLUTION

to this cause ; while Lloyd Morgan gave only 5 per cent,
reduction of the original size. The final reduction of the
organ to zero is still not accounted for by any of these
theories. Calling to aid a failure of the force of heredity,
as Romanes did, can hardly be considered a solution of the
problem. First of all, the force of heredity does not ex-
plain anything in this case. It only restates the problem.
We want to know what the force of heredity is. Secondly,
if the force of heredity does fail, we should have to ex-
plain why it wanes in some cases and not in others. For
the reduction and elimination of rudimentary organs occurs
apparently in the most irregular, haphazard manner.

But can panmixia really reduce an organ ? Plate, in
agreement with Spencer, Eimer, and others, denies any
such possibility. An organ in a given condition of its
existence varies around a mean or average, the plus and
minus variations generally being equally frequent. It
follows, therefore, that if all the existing variations are
crossed in propagation, the organ remains stationary.
Selection only improves the organ by cutting off the minus
variations ; the absence of selection would simply leave
the organ where it was before the selection. At most it
could only sink a very little below the average. That this
is so is seen in organs which are not under the sway of
selection at all. There are numberless such indifferent
species characters, which ought gradually to dwindle
and disappear, yet they remain fairly constant, though
continually exposed to the swamping effect of panmixia.
Panmixia may explain the functional degeneration of an
organ, but cannot explain its actual rudimentation.

Weismann himself in later times abandoned panmixia
as a sufiicient means of explanation, and resorted to a
new theory — that of germinal selection — ^which we shall
discuss presently in detail. But first we shall deal with
the theory of intra-selection.

NEO-DARWINISM

193

(b) I fUra-S election,

Roux in his notable work on " The Struggle for Existence
between Parts of an Organism " (1881) advanced a new
theory, by which he thought to explain the adaptations
of inner structures in contradistinction to external adap-
tations which are due to natural selection. Basing his
principle on the established fact that the very activity of
an organ tends to strengthen it, he showed that parts most
exposed to stimulation will increase at the cost of those
less stimulated, so that a sort of internal struggle goes on
between the various cells and parts of an organ, leading
to direct functional adaptation. Thus, e.g., the spongy
tissue of the bones is arranged in a regular manner, showing
a surprising fitness in its microscopical structure. Now,
the direction of the tiny bone-plates is due, according to
Roux's principle, to the pressure exerted on the bone ;
where it is greatest, there bone-tissue is formed, while at
the points of least pressure bone-tissue is absorbed. In
this way is brought about the minute self-adaptation of
inner parts, which could hardly be explained on the
principle of natural selection. For it is inconceivable that
such minute differences in structure could have suf&cient
survival value for selection to act upon.

The theory of intra-selection, or, as Weismann has
called it, " histonal selection " (selection of tissues), has
been variously estimated. It is true that Roux for the
first time elucidated clearly the principles of functional
stimulation— that is, the law that use leads to increase
and disuse to decrease of the functioning part ; but doubt
has been thrown on his further corollary that such physio-
logical adaptation leads to internal structural selection.
Plate adduces many reasons against such conclusion. First
of all, it is impossible to distinguish clearly between in-
ternal and external adaptations. If the latter can be due
to natural selection, there is no inherent impossibility
that the former might be due to it also. Secondly, the

194 THE FIRST PRINCIPLES OF EVOLUTION

embryonic development, which is essentially nothing else
than a multiplication and laying out of cell complexes,
seems to show that each cell complex develops according
to a definite, predetermined order, depending on the
hereditary qualities of the germ. Thirdly, there are many
structures which do not obey the law of functional adapta-
tion—that is, they do not improve by use, as, e.g., the
teeth, the perceptive parts of the sense-organs, etc. Finally,
not the best-fitted parts are selected by intra-selection,
but those best situated, which situation is originally acci-
dental, and not due to the intrinsic value of the part.
Thus bone-plates are developed where the stress is greatest,
irrespective of any other quality they may possess.

Kellogg is not quite so sweeping in his condemnation of
Roux's theory. He is glad to find in it the possibility of
explaining mechanically "the initiation of certain fine
and delicate inner adaptations,*' which natural selection
is certainly not able to do.

The theory of germinal selection was propounded by
Weismann in 1895-96. By it he thought to overcome
the many difficulties in the way of a full acceptance of a
thoroughgoing selectionist hypothesis of organic evolution,
without having recourse to Lamarckian factors. It was
intended not only to supply an answer to the question of
the degeneration of useless organs, but also to offer an
explanation for various other problems, hitherto con-
sidered insoluble on strict Neo-Darwinian Hues. In short,
it was to be the " rehabilitator *' of natural selection.

We have seen that Roux assumed a struggle for existence
between the different parts of the organism. Weismann,
in his theory of germinal selection, transferred this selective
competition to the germ cells themselves. All modern
theories of heredity assume the germ cells to be constituted
of minute physiological units, which in their totality give
origin to the new individual. Weismann called these

NEO-DARWINISM

195

hereditary units " determinants," because each such unit
determines the quality of the cell or cell complex of the
body arising from it. There is a different kind of deter-
minant for each independently variable cell or cell complex
— e.g., all the red blood-corpuscles are represented in the
germ by one determinant, etc. These determinants have
the faculty of growing and multiplying, just like the
ordinary organic cells.* Now, seeing that only a small
amount of germ substance is originally given with each
individual, the determinants have to grow intensively in
order to supply material for the countless young germ-cells
of the adult organism. We cannot assume an absolutely
even stream of food-supply among the determinants.
There will be slight fluctuations, so that some will get less,
some more, nourishment. This, in its turn, will lead to a
lesser development of the former determinants, while the
latter will become stronger and more powerful. But this
very effect, brought about in the first instance by accidental
variations of the blood-supply, will tend to prolong itself
in the same direction ; for the strong determinant, having
greater assimilative power, will thereby draw still more
nourishment towards itself ; while the weak determinant,
varying in the minus direction, being, as it were, on an
inclined plane, will tend to dwindle more and more. The
latter process will continue till the final disappearance of
the determinant. As each determinant is represented
in the grown-up organism by its corresponding part, the
latter wiU vary in accordance with its determinant, and be
developed in a lesser degree, if its determinant is weaker,
and vice versa.

In this manner Weismann explained the gradual dwind-
ling and elimination of useless organs. It is true, as he
admitted, that panmixia alone does not lead to an accumu-
lation of minus variations, but in time, he argues, minus
variations of the corresponding determinants will be slowly

* See on this subject the textbooks on heredity, especially A.
Weismann: "The Germ-Plasm." J' f j

196 THE FIRST PRINCIPLES OF EVOLUTION

accumulating within the species ; for the individuals mth
the smallest number of useless determinants will have the
advantage in the struggle for life, their useful determinants,
which represent valuable final structures, not being ham-
pered in their food-supply by useless determinants. The
initiation and slow accumulation of minute vanations in
a useful direction is furthered by germinal selection until
they are large enough to attain selective value. Germinal
selection, once started within the germ in a certain direc-
tion, continues automatically, and becomes thus a
source of definite variations," until the latter, if harmful,
are weeded out, or, if useful, are fostered and still further
improved by natural selection. Many other phenomena
of progressive evolution, hitherto ascribed to use-inhent-
ance, can be accounted for by this theory. Thus the de-
generation of the teeth, of the Httle toe, the increase of
shortsightedness in civilized man, may be explained by the
decHne of the corresponding germinal units, while the ongm
of the specific higher human faculties, as music, etc., not
immediately useful in the struggle for Hfe, can be attributed
to the same process in a positive direction. Finally, Weis-
mann would account for the sudden appearance of sports
by a slow intra-germinal accumulation of determinants.
It is all due to the " invisible prelude " within the germ.

Excellent as the theory of germinal selection would
appear to be in the wide appUcation of its pnnciple, it
must be admitted that it rests on a very slender basis
indeed. For it must be understood that the deternunants
are so far ideal, unverified, and unverifiable units of Pro-
fessor Weismann's imagination. But even admitting
their reality, there are various considerations which tell
seriously against the hypothesis. It is unHkely that any-
thing more takes place than an oscillation of the deter-
minants around a given mean, just as in the case of bodily
variations. Various facts can be adduced m favour of
this. Firstly, it is known that most variations fluctuate
evenly around a norm. Secondly, a great number of

NEO-DARWINISM

197

specific characters are fairly constant, thereby showing
that their determinants vary but little. Thirdly, if the
struggle of the determinants lead to a persistent increase
of some and decrease of others, we should see an over-
development of some organs and under-development of
others; in other words, the embryonic development of
the germ would result in monsters. This is certainly not
the case. Weismann himself recognized the force of this
conclusion, and assumed a sort of "self-correction"
within the germ-cell which guards against the excessive
development of the determinants in the positive direction,
while no such inhibitive influence is supposed to exist
with regard to variations in the negative direction. But,
then, the question arises : Why do not all useless organs
disappear completely? Finally, experiments on the
influence of food-supply on development, such as those
by Weismann himself on the larvae of flies, and by others,
have shown that lack of food does not lead to the loss
of structures, but only to a generally dwarfed condition of
the mature individuals.

{d) Coincident Selection.
We have already mentioned the theory of coincident
selection as an auxiliary non-Lamarckian explanation for
the survival of small fluctuating variations. Weismann
had already referred to the fact that, while the initial stages
of germinal variations may not always be effective in the
struggle for life, the innate plasticity of the organism is
often great enough to induce individual modifications
which, though not inheritable, enable the individual to
escape extinction. The individuals with the greatest
amount of organismal adaptability vdll be most successful,
and hand down this innate tendency to their successors,
which process in itself wiU lead to a constant modification
in that direction. But congenital germinal variations,
having the same tendency as the individually acquired
modifications, wiU also appear and have time, under the

igS THE FIRST PRINCIPLES OF EVOLUTION

shelter of the individual modifications, to be accumulated
in successive generations. As Lloyd Morgan puts the
matter : *' Where adaptive variation, v, is similar in direc-
tion to individual modification, m, the organism has an
added chance of survival from the coincidence m-\-v ;
where the variation is antagonistic in direction to the
modification, there is a diminished chance of survival
from the opposition m-v ; hence coincident variation will
be fostered, while opposing variations will be eliminated."

This hypothesis would help to account for two related
difficult points in the theory of natural selection. Firstly,
it would explain the possibility of the slow accumulation
of germinal variations in their first stages before they attain
selective value ; secondly, it would make correlated adapta-
tions feasible by supplying ontogenetic (individually
acquired) modifications, until the material for the appro-
priate germinal adaptations arose.

It has been objected to this theory that, since the indi-
vidually acquired modifications possess the main selective
value in these instances, there is no reason why the corre-
sponding germinal variations should be fostered at all.
The individuals with the right, but slight, congenital
variations would have no special advantage over their
fellows who show no such coincident variations. Nor is
there any ground to assume that the individuals with the
greatest amount of plastic modification in a given direction
will tend to exhibit similar innate variations to a greater
degree than those individuals not possessing this plasticity.

(e) Isolation.

There are left for our consideration in connection with
the theory of evolution two great problems which require
solution — namely, the question of intercrossing and that
of infertility between species. When new varieties arise,
how can they prevail against the old-established forms,
seeing that these, being in the majority, would tend to
swamp them by mere numbers ? Unless intercrossing is

NEO-DARWINISM

199

prevented somehow, the new form would be submerged
at the very commencement of its career. On the other
hand, infertility or absence of intercrossing is a prominent
feature among related species. How can its genesis be
accounted for, as incipient varieties are generally not
infertile among themselves ?

If natural selection led in all instances to the extinction
of the worsted race, the problem of intercrossing would not
arise at all. But in this case evolution would take place
in a ladder-like manner ; there would only be continuous
advance in a single direction, as the progressive types suc-
ceeded each other. This, however, is not what we actually
find in nature. The organic world forms a branching tree
of life ; evolution is progressing in ever-diverging and re-
diverging lines. The battle is not only to the strong, but
the race also to the swift. Many different adaptations
may arise under newly imposed conditions, which, in the
absence of an effective check against interbreeding of the
selected types, would eventually become blended in their
common offspring. In short, isolation is an essential
factor in the process of organic evolution. Its importance
has been variously estimated. Romanes, looking at the
problem from a comprehensive point of view, recognized
in isolation, together with heredity and variation, the three
basal principles " on which is reared the whole super-
structure of organic evolution." From this standpoint,
natural selection would simply be a special case of isolation,
differentiating the fit from the unfit. Of the other forms
of isolation we can distinguish, with Plate, geographical,
biological, and sexual isolation (or segregation), the whole
of them being comprised by Weismann under the term of
" amixia," or " cross-sterility." We shall discuss their
merits seriatim.

Geographical isolation as a means of organic evolution
was first advocated by Moritz Wagner, who in 1868 pro-
pounded a " law of migration " which was intended to re-
place that of natural selection. He held that migration,

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200 THE FIRST_ PRINCIPLES OF EVOLUTION

and consequently geographical isolation, was the real
factor in the formation of species. His theory failed in
so far as it claimed to supersede natural selection, and to
form the sole explanation of organic evolution. But the
principle of geographical or topographical isolation as an
accessory factor in species formation found most forcible
advocacy with later evolutionists, such as Romanes, J. T.
Gulick, and D. S. Jordan. Gulick, and with him Romanes,
distinguishes indiscriminate isolation (separate breeding or
apogamy) from discriminate isolation (segregate breeding
or homogamy). In the former case isolation takes place
indiscriminately from among a given stock, without any
reference to the qualities of the separated sections ; while
in discriminate isolation the different portions of the stock
are selected according to a given principle, as, for instance,
when the stock is divided according to colour, and so on.
Now GuHck showed that, starting with indiscriminate
isolation, the members thus separated by local barriers
tend to vary in a given direction from the parent stock, and
thus gradually verge towards homogamy. To this con-
clusion Gulick was drawn by his researches on the Hawaian
land-snails. These exhibit a divergence in character,
which varies from valley to valley, and can, according to
his view, only be attributed to the e^ect of isolation. For
there is no great variation in the climatic conditions of the
whole district ; while, on the other hand, the difference
between any two forms can roughly be estimated by the
actual distance in mileage between their habitats. It would
follow, then, that mere indiscriminate isolation, which
leads to local segregation of a given stock, is apt to produce
increasing differentiation of the separated sections. For,
as Gulick says : " No two portions of a species possess
exactly the same average character, and therefore the initial
differences are for ever reacting on the environment and
on each other in such a way as to ensure increasing diver-
gence as long as the individuals of the two groups are kept
from intergenerating." Plate, however, would attribute

NEO-DARWINISM

201

their divergence rather to the combination of geographical
isolation with new biological conditions, which would lead
to changed habits and modes of life.

Isolation is possible between various organisms within
the same habitat. If on account of pressure of circum-
stances a group of individuals is forced to seek new con-
ditions of existence, it will, though living in the same dis-
trict, gradually become separated from the parent stock,
and, by the assumption of new habits and features, slowly
diverge from it. This is quite a common consequence of
the struggle for life, and has led to the multiple varieties
of s^cihc forms we see in nature. There are numerous
forms of very near related species, differing only slightly
in their morphological structure and physiological habits.
Any change in the breeding-time, a variation in sexual
maturity, the adoption of different foods, etc., may all
lead to biological isolation.

Morphological divergence brought about by isolation
is often associated with cross-sterihty of the modified
forms. In fact, while infertility between two related species
seems to be the rule, varieties of the same species are
generally more or less fertile with each other. We should,
then, have to explain how this sexual isolation comes
about with the gradual development of varieties into
species. There are two opposing theories. According to
the one, sterihty is the primary factor, while the morpho-
logical differentiation follows. This is the theory of
physiological selection, first enunciated by Catchpool
(1884), and chiefly defended by Romanes. The other
theory puts the morphological divergence first, which,
influencing the sexual function of the organism, leads to
sexual isolation of the respective forms.

Romanes distinctly pointed out that cross-sterility is not
necessarily always the initial or only form of isolation,
causing differentiation of species ; but he held that any
other kind of isolation would prove in the long run ineffec-
tive to attain specific divergence, unless some amount of

NEO-DARWINISM

203

202 THE FIRST PRINCIPLES OF EVOLUTION

cross-infertility ultimately supervened. As a matter of
fact, such infertility is a common feature between species.
It has been argued, however, with good reason against
this theory that physiological isolation by itself is incapable
of producing any specific divergence. It presupposes that
a given group of individuals, while perfectly fertile among
themselves, develop a certain amount of sterility with the
remainder of the stock, without showing any other morpho-
logical distinction. Now, unless this group is capable of
keeping within its own circle during mating — ^which is
impossible, as they are assumed to be distinguished by
no other morphological or physiological feature — they will
interbreed with the remainder, and thus be swamped.
But even if they were to breed among themselves, they
would still not develop in a divergent direction, for they
do not differ from the main stock, according to the theory
itself, in any one trait, except that of sterility.

Inter-racial infertility, then, cannot be the cause of
morphological differentiation, and we must fall back on
the second theory, in order to explain the relation between
specific divergence and cross-sterihty. In favour of this
latter view we can adduce, first of all, two general biological
facts. It is now established that even among well-defined
species crosses are by no means impossible. For instance,
hybrids of lion and tiger, or of wolf and dog, have been
reared, which shows that sterility does not form a primary
condition. Further, it is well known that sUght changes
in the mode of life of an organism will often have a profound
influence on the sex system, and lead to infertility. Ac-
cording to Plate, sexual isolation may ensue upon morpho-
logical differentiation in various ways. There may be no
direct infertility between two forms, yet, the hybrids being
either constitutionally weak or sterile, the result is the
same as if the original forms were sterile with each other ;
or a mutual aversion to intercrossing may arise between the
two forms in question, and thus lead to " preferential
mating." -That such *' race-feeling " often exists is a well-

known fact. Darwin mentions several such instances
from among higher vertebrates, and it has even been ob-
served in lower animals. Recognition marks often aid
in keeping the different breeds apart.

How this racial aversion arises is difficult to teU. In
many cases it may be handed down as a habit from genera-
tion to generation. Where no direct tradition is estab-
lished— as when the young never see their parents — it must
be assumed to arise as a germinal variation, together with
the morphological traits. Whenever such race aversion
arises, specific divergence takes place ; while no polytypic
evolution is possible unless this or some other form of
isolation is present.

Crossing may be made impossible by direct changes in
the sexual organs. These changes may affect either the
external copulating apparatus or the more subtle ** sexucJ
affinity " which exists between the male and female germ-
cell.

Finally, according to Wallace and Weismann, incipient
infertihty between varieties may be gradually increased
by the action of natural selection. Wallace's argument
is as follows : If in a given region two related forms are
adapted to slightly different conditions, the hybrids be-
tween these varieties will on the whole be less adapted.
They will, therefore, be weeded out by natural selection
if they are less fertile than the pure breeds. If, however,
they are just as fertile as the parent types, the whole
population will form a mixed race, which will, on the whole,
be less well adapted to the environment. It would follow
that in the struggle for existence between two such regions
the species with the mutually infertile varieties would be
favoured by natural selection. Species with varieties
which are infertile inter se would tend to displace species
with mutually fertile varieties.

There are several arguments to be adduced against
Wallace's conclusion. Darwin himself did not see his
way to accept this theory. The facts that sterility fre-

riatft^llJ

204 THE FIRST PRINCIPLES OF EVOLUTION

quently exists between species not inhabiting the same
region, and that there are cases of reciprocal crosses, where
one form can be fertilized by the other, but not vice versa,
show that sterility does occur without the help of natural
selection. Furthermore, Plate reasoned that all that
would happen in the cases adduced by Wallace would be
an ehmination of the hybrids in both instances, only it
would be somewhat slower with the mutually fertile
varieties. If the infertility were correlated with an in-
different character, natural selection would not be able
to influence it at all. On the other hand, if there existed
correlation with a useful trait, the combination of such
traits in the hybrid should act rather favourably than
otherwise, seeing that, according to Wallace himself, " the
offspring of crossed unions will be more vigorous on account
of the cross."

We have already mentioned that there are two additional
factors which effectively dispose of the difficulty of inter-
crossing. In Mendelian inheritance the hybrids of the
original strains breed out pure in the next generations in
spite of the initial blend, so that, whenever a new character
follows the Mendelian law, there is no fear of its being
swamped even without isolation. The other factor — that
of mutation — ^we shall discuss fully in the next chapter.

I 1^

-^A

CHAPTER IX

THEORIES OF EYOI^VTIOl^— Continued

We have so far dealt with the two most prominent theories
of organic evolution, and have seen that neither of them
offers a complete solution of all the problems involved.
Darwin's theory of natural selection, after its first trimnph,
has in later days been discovered to be weak at many points,
and has had to be propped up with various auxiliary
hypotheses. Some people in whom, it would seem, the
wish was father to the thought, saw herein the complete
breakdown of the modern theory of organic evolution. It
will have become evident from the foregoing, however,
that the principle of evolution does not stand or fall with
Darwin's explanation of it. Side by side with the criticism
of Darwin's theory a good deal of constructive work has
been going on, and as the outcome we have several new
theories which are competing with the old ones in their
aim of supplying the key to the problem of organic evolu-
tion. Some of these theories are wholly antagonistic to
natural selection ; others, again, whilst trying to replace it,
would allot to it a not unimportant secondary position.

We can distinguish two main modern schools — the
mutationists, who look upon discontinuous variations
(mutations) as the material of organic evolution (hetero-
genesis), and those scientists who assume a determinate
progressive movement in the organic world as an intrinsic
part of its organization (orthogenesis).

205

206 THE FIRST PRINCIPLES OF EVOLUTION

I. Heterogenesis.

Darwin distinguished two kinds of variability in organ-
isms. First there is definite variabiUty, " when all, or
nearly all, the offspring of individuals exposed to certain
conditions during several generations are modified m the
same manner." These are now called " modifications or
" somatic (bodily) variations "; for according to the now
generaUy accepted belief, they affect the parental body
only and are not transmissible to the offspnng. Darwin
himself, as we have seen, held them to be inheritable to a
certain extent, and saw in them an accessory means of
organic evolution. The second kind of variabihty is the
indefinite or spontaneous ; indefinite, because it shows no
definite direction, leading to " the endless slight pecuhanties
which distinguish the individuals of the same species ;
spontaneous, because no known cause could be assigned to
it by Darwin. *' Occasionally even strongly marked differ-
ences appear " ; " deviations of structure so strongly pro-
nounced as to deserve to be called 'monstrosities.
These are the " single variations " or " sports " of Darwin.
Since Darwin's time a good deal of light has been thrown
on the problem of variation. We now call Darwin's
indefinite variations "germinal variations"; for they have
been found to be due to the intrinsic structure of the
hereditary substance of the germ-cells themselves. Of
germinal variations there are two kindsr-the Darwinian
individual variations, now termed " fluctuating" or " con-
tinuous variations," and the discontinuous variations, to
which belong Darwin's single variations or sports. As to
the former, they are called " fluctuating " because they
fluctuate around an average or mean. They can be
arranged in a continuous graduated series, which can be
represented by frequency-curves. In Fig. 76 the stature
of men in inches is plotted along the horizontal hne,
while the distance of the curve from that line indicates
the number of men of each given height. We see that.

HETEROGENESIS

207

f I

as the men approach the average or mean stature, their
number graduaUy increases, only to decrease again pro-
portionately, as the stature reaches the other extreme.
Darwin based the process of organic evolution on the slow
accumulation of these small fluctuating variations, which,
taken up by natural selection and directed into definite
lines; lead graduaUy to the origination of new species
Extreme variations or sports do occur at times but though
they may give rise occasionally to new breeds-instance

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the Ancon sheep, the Niata cattle, etc.-they are too rare.
They are liable to be swamped and are therefore unable
to form the main material for new species.

Now the mutation theory (or heterogenesis) lays stress
precisely on these discontinuous variations as a means ot
organic evolution. The idea of progressive development
of species by steps or jumps has been advocated from time
to time. Von KoUicker proposed a theory of heterogenesis
as early as 1864. The rediscoveries (in iQoo) of the
Mendelian laws of heredity, according to which mhentance
takes place by definite unit-characters not merging into

2o8 THE FIRST PRINCIPLES OF EVOLUTION

each other ; further, the studies of Bateson and others on
the discontinuity of variations, gradually led scientists to a
new view of the process of organic evolution. Korschinsky
formulated a theory of heterogenesis in a series of papers
(1899-1901). But the main exponent of the new school is
the Dutch botanist Hugo de Vries, who embodied his labours
in his work on " The Mutation Theory " (1900), which has
become a classic on the subject, and later in a more con-
densed form in his book " Species and Varieties, their Ongin

by Mutation " (1906). , ^ • ^

To understand his position, we must go somewhat into
his account of biological species. It is well known that
Linnseus was the first to estabhsh the species as a unit of
classification, beUeving them to be the permanent entities
originally created. Before his time the genera held this
rank, and the species and subspecies were supposed to be
derived from them. It is a commonplace now how Darwin
demonstrated the gradual evolution of all organic beings,
showing that species originated from varieties, the latter
being but " beginning species." It is clear from this that
species, as originally conceived by Linnaeus, are merely
conventional taxonomic units, which comprise a greater or
smaller number of subspecies or varieties. On closer
examination, now, it is found, as De Vries's investigations
show that these smaller units are by no means all equivalent
to each other. In some cases all the subdivisions are of
equal rank ; they seem to have no central important form
from which they can be derived. They are distinguished
from each other by a number of differences in neariy all
their organs and qualities, which differences are due to
newly arising germinal units. Such forms De Vries desig-
nated as " elementary species." Thus the ordinary syste-
matic species of the whitlow-grass {Draba verna) and of the
violet (Viola tricolor) consist of numerous well-defined sub-
species, the former comprising over 200 such constant
forms. On the other hand, we have cases where the
varieties are clearly derivative from a parent-species, by

• \

t y

HETEROGENESIS

205

the addition (of a previously lost) or the loss of a single
marked characteristic. These are the vaneties m De
Vries's sense. It must be pointed out at once that ele-
mentary species, as weU as De Vries's varieties, onginate
by mutation-that is, by a single definite sudden change of
the germinal substance. New forms are estabUshed by
mutation in one step ; they are from the very beginmng
fully developed in all their characteristics, as the extensive
researches of De Vries on the evening primrose (CEnothera
lamarckiana) have shown, and they breed true. The muta-
tion, then, does not alter the original parent organism ; but
new branches, as it were, arise from the main hne, forming
independent constant species at the side of the parent-
species. Draba verna, according to this interpretation,
would have to be looked upon as a conglomerate of elemen-
tary species, aU having originated by mutation. The new
mutations may prove to be either useful for the species in
the battle of Ufe, they may be indifferent, or they may be
harmful. In the last case natural selection steps in and
removes them, just as in Darwin's theory. It is through
the weeding out of a number of arising mutations that gaps
are produced in the Une of evolution, allowing us to make
larger taxonomic divisions in the orgamc world. The
mutation theory, then, as is apparent, is in direct opposition
to Darwin's view of the slow persistent change of species
through the gradual accmnulation of small individual
variations. On the other hand, De Vries s hypothesis
agrees with Darwin's in attributing to natural selectipn the
ultimate deciding factor,* only we must understand that
survival of the fittest implies here, as Th. H- Morgan has

* Korschinsky denies that adaptation, which comes about
through the struggle for existence, is identical with advance Natur^
selection according to him, is solely an inunical factor m organic
::oTurn;S ofi branches from the tree of life, w^^^^^^^^
otherwise " persist in blossoming condition. He rather beheves
m a special tendency towards advance in the organic world (see

the section on Orthogenesis).

210 THE FIRST PRINCIPLES OF EVOLUTION

put it, the survival of the fittest species (in the De Vriesian

sense).

The contmuous variations which Darwin relied upon as
the material of organic evolution,* De Vries regards as
bodily mortifications. He sees in them the mere effect of
the conditions of nutrition in the largest sense— light space,
temperature, etc. Such " fluctuations " are, according to
De Vries, who is an anti-Lamarkian, not inheritable, and
cannot, therefore, have anything to do with the development
of specific forms. Selection may take place from among
these, fluctuations, but such intra-specific selection, as De
Vries calls it, must soon find its limit after a few generations.
Moreover, accordmg to Galton's law of regression, it is Hable
to revert towards the old level, unless selection is kept up
unremittingly, t Mutations, on the contrary, are constant
from the beginning, and remain so in successive generations. .
They are therefore able to hold their own without further
selection, except in so far as mutations not adapted to their
surroundings succumb in the struggle for existence. The
mutants themselves show fluctuating variability of their
own, which, however, does not affect their intrinsic quahties.
The same mutations arise in a number of individuals of the
same species over and over again. De Vries assumed that
there exist active periods of mutation for each species,
occurring from time to time and alternating with periods
of quiescence, which may last hundreds or thousands of

years.

It must be distinctly understood that mutations are not
necessarily large. The steps may be shght, though each
step means a definite constant departure from the parent
type. The fundamental point of De Vries's conception

* Darwin originally laid the chief stress on single variations—
i.e., the mutations of De Vries— but, owing to the criticism of
Fleeming Jenkin on the effect of swamping, he changed his views,
and adopted the individual variations as the main material of
oiganic evolution.

I See on this point the textbooks on heredity (Biometrics).

HETEROGENESIS

211

of mutations is that they are due to germinal unit char-
acters. Each germinal change involves a distinct step,
there being no gradations between the difEerent units.
This view accords well with the Mendehan theory of
heredity, according to which individual parental traits are
represented in the germ by distinct units, which may
combine, but do not blend. Indeed, De Vries found that
crosses between varieties (De Vriesian mutant-varieties)
Mendelize, that is, follow on breeding the Mendelian
law of inheritance.

Now, what is the evidence De Vries has to offer for his
theory of mutation ? Apart from general theoretical con-
siderations and an analysis of an abundant mass of
botanical facts, his main work consists in researches on
the mutations of the now famous evening primrose of
Lamarck {(Enothera lamarckiana). This plant, which is
at home in America and is generally cultivated in gardens,
De Vries found growing wild in a potato-field near Hilver-
sum, Amsterdam. He also observed in the same field what
he considered to be two new related elementary species—
viz., (Enothera hrevistylis and (E. Icevifolia ; the former, as
the' name indicates, with short style, the other smooth-
leaved. He transferred the plants for experimental
observation. The self-fertilized parent-form of the
lamarckiana yielded in successive years a number of new
forms, which proved to be constant. Fig. 77 shows the
various mutations which appeared in the successive genera-
tions, the horizontal lines giving all the descendants from
the lamarckiana parents for each year. Cultures from
other (Enothera forms produced similar results.

It must be admitted that, apart from the botanical
evidence, the zoological side of the question is represented
only by a few observed cases of mutations. Still the
experimental skill of De Vries and his acumen in mar-
shalling his facts have convinced a good many evolutionists
of the value of his theory, the more so as Darwinism of the
old type has been rather oppressed of late with objections.

212 THE FIRST PRINCIPLES OF EVOLUTION

which the mutation theory seems in a much better position
to overcome. Thus, Th. H. Morgan enumerates many
advantages of this theory as against Darwinism. It
accounts without difficulty for the incipient stages in the
development of organs ; for organs, arising by mutation,
may persist, even though they possess no value for the
race The danger of swamping is lessened, as mutations
arise repeatedly over and over again, and are constant from
the beginning, etc. In spite of all this, it would be wrong
to substitute the mutation theory for Darwini^ »i toto,
and to imagine that it is able to solve all the difficulties of
organic evolution, as Th. H. Morgan seems to indicate.

HETEROGENESIS

213

Genera-
tion.

0.
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0.
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longa.

rubri-
nervis.

CEnothera .
lamarckiana.-

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nella.

0.
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73
142

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tillans.

II.

III.

IV.

VI.

VII.

VIII.

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Mutations of CEnothera Lamarckiana. (After
De Vries.)

He himself has pointed out that there is so far no evidence
to show that successive mutations " heap up " new char-
acters in definite lines, which, after all, remains the funda-
mental problem of organic evolution. As to the value of
the mutation theory in itself, there seems to be no doubt
that it stands on firm ground as regards the experimental
facts. The question is whether mutations are a common
enough occurrence in the organic world to serve as the
material for organic evolution. De Vries himself, though
he often speaks of mutations as being frequent, estimates
their average appearance as from i to 2 per cent, only
of the parent-stock. Seeing that the majority are

weeded out again in the struggle for existence, there seems
to be little chance for them to yield enough material for
progressive evolution.

The further question arises, whether the individual vana-
tions of Darwin can be brushed aside in such a wholesale
manner as De Vries has adopted. Plate sees in De Vries's
account of Darwin's views nothing but a complete misunder-
standing. He tries to show that De Vries mistook Darwin's
individual variations, and classed them as non-inheritable
Lamarckian modifications, while Darwin himself speaks of
non-transmissible and transmissible characters, and took
only the latter as the material of organic evolution. The
truth is that Darwin did not clearly distinguish between
the two kinds of variations, nor was there made at his time
a clear difference between continuous and discontinuous
variations, except in so far as sports were known, which,
as the name implies, were looked upon as exceptional.
Since his time, however, the laws of variation have been
studied more minutely, and we have now two camps—
the mutationists, who differentiate sharply between con-
tinuous and discontinuous variations, and the biome-
tricians, who do not acknowledge any such dividing-
line. At present it is difficult to decide between
these schools. It would appear from Johannsen's ex-
periments " On the Inheritance in Populations and Pure
Lines " that selection in populations (i.e., mixed strains
or lines) leads to a change of type by sifting out succes-
sively the intercrossed deviating lines. There takes place
a gradual " purification " of the strains, until at the end
practically one pure line is left, which cannot further be
improved upon. Such a pure line (i.e., a line derived from
a single ancestor) would thus correspond to an elementary
species of De Vries. On the other hand, the same author
has shown that frequency-curves apply also to inheritable
variations of mixed populations, proving thereby that
they are not a differentiating mark between modifications
and variations, as De Vries thinks. Besides that, as

♦ ;*

212 THE FIRST PRINCIPLES OF EVOLUTION

which the mutation theory seems in a much better position
to overcome. Thus, Th. H. Morgan enumerates many
advantages of this theory as against Danvmism. It
accounts without difficulty for the mcipient stages m the
development of organs ; for organs, arismg by mutation,
may persist, even though they possess no value for the
race. The danger of swamping is lessened, as mutations
arise repeatedly over and over again, and are constant from
the beginning, etc. In spite of aU this, it would be wrong
to substitute the mutation theory for Darwini^ tn Mo
and to imagine that it is able to solve all the difficulties of
organic evolution, as Th. H. Morgan seems to indicate.

Genera-
tion.

II.

III.

IV.

VI.

VII.

VIII.

gigas.

O.
albida.

O ob-
loDga.

rubri-
nervis.

25
II

(Enothera
lamarokiana.

176

9
I

8
20

3
o

I 5 ,000

10,000
14,000
8,000
18,00
3,000
1,700

O.na-
nella.

0.
lata.

3
60

9
II

O. scin-
tillans.

73
142

I
6
I

Fig 77 —Mutations of (Enothera Lamarckiana. (After
^ ^^' De Vries.)

He himself has pointed out that there is so far no evidence
to show that successive mutations " heap up " new char-
acters in definite lines, which, after all, remains the funda-
mental problem of organic evolution. As to the value of
the mutation theory in itself, there seems to be no doubt
that it stands on firm ground as regards the experimental
facts The question is whether mutations are a common
enough occurrence in the organic world to serve as the
material for organic evolution. De Vries himself, though
he often speaks of mutations as being frequent, estimates
their average appearance as from i to 2 per cent, only
of the parent-stock. Seeing that the majority are

HETEROGENESIS

213

weeded out again in the struggle for existence, there seems
to be little chance for them to yield enough matenal for
progressive evolution.

The further question arises, whether the individual vana-
tions of Darwin can be brushed aside in such a wholesale
manner as De Vries has adopted. Plate sees in De Vries's
account of Darwin's views nothing but a complete misunder-
standing. He tries to show that De Vries mistook Darwin's
individual variations, and classed them as non-inheritable
Lamarckian modifications, while Darwin himself speaks of
non-transmissible and transmissible characters, and took
only the latter as the material of organic evolution. The
truth is that Darwin did not clearly distinguish between
the two kinds of variations, nor was there made at his tune
a clear difference between continuous and discontinuous
variations, except in so far as sports were known, which,
as the name implies, were looked upon as exceptional.
Since his time, however, the laws of variation have been
studied more minutely, and we have now two camps—
the mutationists, who differentiate sharply between con-
tinuous and discontinuous variations, and the biome-
tricians, who do not acknowledge any such dividing-
Une. At present it is difficult to decide between
these schools. It would appear from Johannsen's ex-
periments " On the Inheritance in Populations and Pure
Lines " that selection in populations (i.e., mixed strains
or lines) leads to a change of type by sifting out succes-
sively the intercrossed deviating lines. There takes place
a gradual " purification " of the strains, until at the end
practically one pure line is left, which cannot further be
improved upon. Such a pure line (i.e., a line derived from
a single ancestor) would thus correspond to an elementary
species of De Vries. On the other hand, the same author
has shown that frequency-curves apply also to inheritable
variations of mixed populations, proving thereby that
they are not a differentiating mark between modifications
and variations, as De Vries thinks. Besides that, as

214 THE FIRST PRINCIPLES OF EVOLUTION

W R F Weldon commented in his review of De Vries's
- Mutation Theory," we are at the present stage of our
knowledge unable to say how much of an organism is due
to environmental factors, how much to the inborn germmal

factor.

2. Orthogenesis.

The outstanding problem of organic evolution still re-
mains unsolved : Whence the variations which form the
material for the origination of new species ? The Dar-
winian theory of natural selection gives no answer to this
question. It only deals with the selection of specific traits,
which from a " wholly fortuitous, miscellaneous, inde-
terminate" mass of variations are directed into definite
lines of development. This process, which may be called
- orthoselection," must be distinguished from orthogenesis,
which implies that the original lines of variation are from
the very beginning limited to a few well-marked direc-
tions • that, in fact, the evolution of the organic world is
due to an inherent growth of the organism. This organic
growth is, as the upholders of vitalism maintam, a con-
dition sui generis of the living substance, independent of
the influence of external physical conditions ; while others,
like Eimer, Cope, etc., more in accordance with the mechan-
istic interpretation of life, would rather attribute organic
evolution to the interaction between the Uving organism
and its inorganic environment. We shaU deal first with
the mechanistic theories, then with those of the vitalists.

(a) Mechanistic Theories,
Whilst discussing the difficulties of the Darwinian
theory, we mentioned two auxiliary hypotheses of natural
selection, both devised in order to show how definite y
directed adaptations may be brought about at least m
their beginnings, by mechanical principles. Roux s intra,
selection and Weismann's germinal selection may both be
looked upon as selectionist attempts at an orthogenetic

ORTHOGENESIS

215

explanation of variations, though both theories soon hand
over their further elaboration to the exclusive control of
natural selection. Lamarckism, too, by its insistence on
the accumulating efEect of use and disuse and the direct
result of persistent functional stimuU, is in a sense a theory
of definitely directed lines of development. As a matter of
fact, the two most prominent mechanistic theories of
orthogenesis, those of Professors Eimer and Cope, are
based on Lamarckian prmciples ; though Eimer himself,
who first propounded a definite theory of orthogenesis,
is careful to point out that his theory of orthogenesis is
not identical with Lamarckism.

Professor Eimer was led to the discovery of the principle
of orthogenesis as a means of organic evolution by his
intunate studies on the dark blue wall lizard (Lacerta
murdis ccerulea) of Capri. He showed that the markings
of the lizard followed definite rules. Similar principles
were found to apply to other classes of animals — beetles,
butterflies, molluscs, etc. Several laws of orthogenesis
have thus been enunciated by him : (i) The markings of
animals in general do not occur haphazard, but are deter-
mined by the laws of growth. The primitive longitudinal
striping is transmuted into spots; these by confluence
form cross-striping ; while uniform colouring foUows as
the last of a regular series of successive markings (Fig. 78).
(2) " The new markings (or other morphological characters
of the body covering) appear on the body of the animal
from behind forward and from above downward, or con-
versely, whilst the old ones disappear in the same direction
and succession." (3) *' The male is ordmarily a step or so
in advance of the female in expressing the direction of
development, though there may exceptionally occur female
preponderance.*' (4) " A succession of transformations,
each following the other, runs along over the body of the
animal" in a wave-like fashion. (5) "The same directions
of evolution may be operative in different and not im-
mediately related forms, and may lead to quite similar

mMfa'jj!;i

IM|N>«M«nMfM|RM

D ^ .

Fig. 78. — Colour-Markings of Lacerta muralis.

4From " Primary Factors of Organic Evolution;' by E. D. Cope,)

ORTHOGENESIS

217

morphological results." (6) "Different characters may
TeveloS the same organism in different degrees and in
SS directions." (7) " The directions of evohatH>n
may get reversed and turned back to their startmg-pomt^
is)'' Evolution may often long remam at a standstill at
a definite stage " (genepistasis) ; etc , etc. ^ ^^ ^„.t

In order to fully understand Emier's views, we must
nobit out that, according to him, the whole organic world
CsTcontinuous growth (phyletic 6«>wth). which is
m^ely the sum of modifications due to the growth of the-
Sparate individuals. Such individual growth is the out-
come of the interaction of inner constitutional causes and
external environmental conditions (food, warmth etc )
Us the variety of external factors which necessarily leads to
variety of growth, so that his theory thus takes for granted.
S LmSck, the inheritance of acquired charac^rs.
Organic evolution is thus nothing but phyletic growth,
broken up into separate units (species, etc.). Such differ-
entiation of distinct species takes place by g^nepistasis-
that is, some organic forms become arrested m their
growth, whUe others advance. The cessation of develop-
ment may affect some of the characters of the orgaiiism,
Se oth^ers progress. No further process of isoMion
is necessarily called to aid in order to keep the various
species distinct. Natural selection only acts subordmately
as an eliminating factor of unfit species.

Professor Cope's theory is simOar m its ¥^<^]f^\ "e
too, assumes a growth-force (bathmism). It is the
modifications of this energy which constitute evolut on
The interaction of this growth-force with external stmiuli
results in physiogenesis and kinetogenesis, ac^ordrng as
the influence is physico-chemical, affectmg the organism
directly, or mechanical, affecting the organism mdirectly
through the effects of use and disuse. He also posits a
primitive consciousness (archasthetism^, precedmg m
time and in history the evolution of the greater part of
plants and animals." " Life is," accordmg to this theory,

2i8 THE FIRST PRINCIPLES OF EVOLUTION

•' energy directed by sensibUity." Cope produces a vast
mass ?f pal«.ntological facts showing definitely directed
Unes ^f evSon, efpeciaUy with regard to o^ous struc-
tures (bones, teeth, etc.), of vertebrate animals _

It must be admitted that, on the whole, the evidence
in favour of determinate variation by orthogenesis is great
S —t, though it ren^ains a moot Po-t whether J
variations run in a few well-marked grooves. Or Oogenesis
Lrtainlv supplies an explanation to some of the vexed
SoSis of evolution. It explains the first beginnings of
variations it accounts for the excessive formation of cer ain
leatuS animals which so often lead to the extinction
of S possessors. It also affords the key to the pa allel
Lelopment seen in different lines of evolution and lead-
So Sgous structures in different classes of organisms
!lls when I lens, e.g.. is added to the pigment spots of
manv lower otherwise unrelated anunals, etc.

The one drawback of the orthogenetic theories lies in
the fact that they are based on the inheritance of acquired
c»es, which so far is not a substantiated aco
Snce BuT, as Plate says, it is well conceivable that
oXineS may hold good without the necessity of this
SSn S long as we believe that orthogenetic varia-
SrCbe iSced in the germ-cells directly through
the influence of external conditions.

(h) Vitalistic Theories.
All the theories that we have considered ^o f ar ^r^^^^^^^
on a mechanistic interpretation of life. J}^^^//^^^ l?"
Wanted that the phenomena of life exhibited by the
SvX organism as well as by the race, are explamable
or wm b?explainabk^^^ the interaction of physico-
:^pmical forces This mechanistic school, though suc-
SrL Sy establishing once for all the theory o^
thf ^adual transformation of species against the old
iSief^of spLil^ creation, has of late largely lost prestige
"Sh certain biologists through its inabDity to supply a

ORTHOGENESIS

219

satisfactory theory of the mode of evolution. We have
seen that there exists a superabundance of theories and
auxiliary hypotheses, without there being any single one
which is able to solve the problem in its entirety. Partly
on the strength of this negative criticism, partly from a
positive basis of its own, the newly arising school of Neo-
Vitalism rejects *«/o/o the Darwinian or any other mechan-
istic explanation of evolution, and substitutes for it a
teleological interpretation. They maintain that life is in
its ultimate essence more than a mere conjunction of
physico-chemical forces, that the actions of organized
beings proceed teleologically — i.e., purposefully — and that
therefore a special vital principle must be assumed, which,
whilst controlling the energetic forces of the organism, is
itself not subject to the laws of matter and force. Seeing
that all life is dominated by a teleological factor, evolution,
too, can find an explanation only on the assumption of
inherent final causes.

Such an internal " automatic perfecting principle " as
a means of the progressive development of the organic
world was first proposed by Carl von Naegeli in his
" Mechanico-Physiological Theory of Evolution " (1884),
without, however, finding any wide acceptance.* It is
only of late that the vitalistic school, mainly represented
by German biologists, has brought the '* autonomic factor "
once more into prominence.

We cannot here enter into a detailed discussion of the
various theories of neo-vitalism, but shall review shortly
the three main trends of thought, as distinguished by
Plate — viz., the agnostic, the psychical, and the meta-
physical.

Agnostic vitalism, as defended by G. Wolff, denies the
possibility of a mechanistic explanation of biological
problems, but refrains from advancing a vitalistic solution
of its own as still being beyond our understanding. In

* Naegeli himself looked upon such a principle as by no means
indicative of vitalism.

220 THE FIRST PRINCIPLES OF EVOLUTION

other words, it gives up the problem for the time
being.

The psychical vitalism of Pauly, France, and others,
goes back in its principles to Lamarckism, which includes
in its teachings a psychological element as a formative
factor of organic progress. Lamarck's theorem that " inner
feelings " create desires in the organisms, and thereby lead
to the fulfilment of such desires by the development of
existing or the creation of new organs, is considered by
many authors as a vitalistic principle, and is certainly
claimed as such by modern psycho-vitalists. They have,
however, extended this principle, and maintain that all
organic happenings — ^those of the most primitive organisms
as much as those of the highest rational beings — are in the
last instance dependent on a psychic element. According
to this theory of voluntarism, as it is also called, we should
have to assume that every cell has an understanding, a
soul, which enables it to act purposefully for the fulfilment
of its own ends. The only and final objection against such
an assimiption is that it gives an unwarranted extension to
the meaning of the terms consciousness and thought, which
are generally reserved for organisms with a developed
nervous system.*

Coming now to metaphysical vitaHsm, which represents
the most prominent school of this mode of thought, it
assumes as the basis of all vital phenomena a non-energetic,
immaterial force, which directs and transforms the energies
of the hving organism in a teleological sense. H. Driesch
calls this immanent, autonomous principle the " entelechy,*'
borrowing the term from the Aristotelian " entelecheia " —
i.e.y '* that which has the end in itself." Reinke speaks in
a similcir sense of " dominants." The same force as deter-
mines the development and form of the organism is also
responsible for the development of the race, which thus

* It must be remarked that a psychical factor does not necessarily
imply a vitalistic interpretation, unless we assume that psychic
phenomena are eo ipso of the vitalistic order.

ORTHOGENESIS

221

proceeds according to an immanent teleological final

*'^Ftaallv we must mention in this connection the " Crea-
tivelvdution " of the eminent French pMo^^P^^^.^ Henn
Bergson, who in his book has certamly produced the most
Sund and epoch-making work in the field of evolution
sTnce the days of Darwin. He is, like the scientists pre-
Xusly mentioned, a vitalist, beUeving in a "vrtal un-
pegs "• but he differs from them in this respect, that he
does not attribute to life a teleological tendency. Har-
mly is tather behind us than before. It is due to a„
Sentity of impulsion, and not to a common aspiration,
it k the vital impetus which is the fundamental cau^ of
variations. Life creates a continuous series of unfore-
seeable forms during the evolutionary process, ^ich
•ZZs out like a sheaf," the different divergent hues being
muSly complementary. " The evolution of life issome-
Sg other than a series of adaptations to accidental cir-
cumstances, also it is not the realization of a plan.^ . .
Evolution is a creation unceasingly renewed it creates.
asT^Zs on, not only the forms of life, but the idea that
wilfe'nSe the inteUect to understand it." Adaptation to
external conditions explains only " the sinuosities of the
movement of evolution." Evolution, the movement itself,
Tdue to the original " internal push, that has carried life
by more and more complex forms, to higher and higher

^^jS'^mlm "tendencies" of the evolutionary lines into
whiSi the current of life has dijided.itself, are foUowed by
Bergson in a most ingenious and original manner. He sees
ff Edentity of the original vital impetus the explanation
of the parallel development in different classes of organisms ;
as for'^instance, the origin of the similar structure of the
eve in such different classes as molluscs and vertebrata.
^As to the metaphysical side of Bergson's P^of Pl^y^^^f
must reluctantly forgo the details of his ^^terly expo^-
tion of the connection between life and matter. We must

•(:

222 THE FIRST PRINCIPLES OF EVOLUTION

understand, however, that Bergson reverses the usual ^
rir of ° vents. According to him, n^atter does not ^o^ )
AuL life but life creates matter, cuttmg it out of the /
\ contii^uhy oTbecoming " according to individualneeds /
^' How far does metaphysical vitalism -cceed m solv mg
the problem of evolution ? We must remember that it is
in the explanation of the origm of variations that the
"echLfstfc theories fail. This is the mam criticism
levelled against the Darwinian school. Now, do tne
vilalists show a better resuh here ? Do they account for
Se happenings of life by their metaphysical principles ?

In the first instance, is everythmg arranged as if it
tendeltowards a harmonious end ? Many phe'iomena o
lifp rertainlv occur which point to such a belief. But the
merrfit Jhat^o many organic forms have died out through
S ofadaptation ; further, that misformed organisms
somettaesarise, shows that the vital factor often fails m
thb s^sed eleological aim. The adherents of thi
do^trSave tried to escape the dilemma by -umingjhat
not purposefulness {Zwechmdssigkext), but ^imMness
tielreUgkeii) alone is sufficient o chara.t«i.e ^h
organism, the end not necessarily being .^"a mable. mt
wUh this admission the teleological principle of hfe is

^'ftk^lS^'^^r.s as entelechy, dominants, ^tal
• !+„? Ptr really carry us any further m our under-
Sding of orgink procesis ? RLke himself admits that
fhTacS of'his d'ominants cannot be conceived by ou
intellect They certainly cannot be verified, and the same
S es to all the other metaphysical categories However
S and impressive Bergson's illumination of the evd-
Znarv tjrocess may be, examined carefully it turns out
o be noCo e tha/a description of the different Imes o
evMutbn so far as known. It posits the origmal vital
movement, but does not tell us why it was constrained to
. Bergson. as we have seen, condemns radical finalism as much
as radical mechanism.

ri«

ORTHOGENESIS

223

break up into different tendencies, and that of a particular
kind and in a particular order ; and this is, after all, what
we are seeking for.

3. Conclusion.

Having traced our course through the intricacies of
modern evolutionary theory, what do we find as the result
of our rather prolonged inquiry ? It has become evident
that the problem is by no means so simple as the pioneers
of evolution thought. And, we must add, the difficulties
have by no means been overcome by their successors.
One thing is sure, however : organic evolution or the trans-
formation of living beings has been established as a scientific
fact on a sufficient and independent basis, and is now the
accepted creed of the age. The only question is : How has
this progressive differentiation of the organic world come
about ? Here it must be said that, while there are now
a good many scientists who would discard natural selection
as a satisfactory mode of explanation of the origin of
species, there are very few indeed who would not allot
to it at least a secondary influence. If it is not " guiding
the ramifications of the tree of life," in any case " it applies
the pruning-knife to them," lopping off useless branches,
and thus making room for the development of the fittest.
Natural selection is at present, so far as it goes, the only
acceptable theory of adaptation ; for Lamarckism cannot
be considered as proven, so long as its basis, the inheritance
of acquired characters, has not been established; and
teleological vitaHsm, whilst assuming a purposeful end^
is far from having proved its thesis.

But— and here it is that the deficiency of natural
selection makes itself apparent— while natural selection
explains the further development of adaptive variations,
once they have attained survival-value, it certainly cannot
account for the " origin of the fit." This is the central
problem which has had to be solved since Darwin. The
mutation theory, by assuming large mutations instead of

1 1

224 THE FIRST PRINCIPLES OF EVOLUTION

small variations, overcomes one weak point of Darwinism,
that of the progressive accumulation of small initial steps ;
but, still, it simply posits the mutations : it does not account
for their accumulation in definite directions (save by rely-
ing on natural selection). Orthogenesis seeks to overcome
both these difficulties by crediting the organism with an
innate tendency towards directive lines of variation. It
thus solves the problem of the beginning of variations,
before natural selection is able to take hold of them. But
it is still left an open question why the organism varies in
definite directions. Eimer and his adherents would
attribute the directive influence to the efEects of the environ-
ment upon the organism— a theory which assumes
Lamarckian factors ; while the vitalistic school upholds a
metaphysical principle, which, as we have seen, is not
amenable to scientific inquiry.

In short, while natural selection can be looked upon as
the efficient cause of the progress of evolutionary lines,
their first beginnings must be attributed to a still " un-
known factor in evolution."

SECTION III

SUPERORGANIC EVOLUTION

It is customary to make a broad distinction between the
inorganic and organic, the former embracing the physical
world of lifeless matter, the latter including the living
organisms and their phenomena. To these two divisions
Herbert Spencer has added a third— namely, the super-
organic, which deals with " facts, not presented by any
organic body singly, but which result from the actions
of aggregated organic bodies." These phenomena, though
already apparent to a certain extent among animals, are
chiefly characteristic of " mankind as socially united " ;
so that superorganic evolution is concerned mainly with the
progressive development of human society. On the prin-
ciple of the continuity of evolution, we should naturally
expect no definite break between organic and superorganic
phenomena. The links between them are formed by those
fkcts which are classed as mental and moral. We have
already had occasion to point out that the mind must be
held to be under the sway of natural selection, just like
the other phenomena of the living organism. We must
now deal fuUy with these " higher " faculties, which
lead ultimately to the whole imposing superstructure of
civilized society. We shall accordingly discuss, under
the head of social evolution, first mental and moral evolu-
tion, then the general progress of human society, and lastly
the special development of the various social institutions.

225

CHAPTER X

SOCIAL EVOLUTION

I. Mental Evolution.

Before entering on our subject proper, we must deal with
certain preliminary questions in order to clear the issue
before us. We have indicated above that mental pheno-
mena must be included in the general scheme of evolution.
It has been shown in a previous chapter that there is no
ground for treating the higher faculties of man as belonging
to a distinct category of their own. Here we must add
that consciousness in general cannot be held to be a
separate entity lying outside the natural law of evolution.

For, at whatever stage consciousness may be considered
to have had its beginnings, comparative psychology has
made it clear that the phenomena of the mind evidence
themselves in close parallelism with the development of
the sensory and nervous structures of the organism. *' All
mental process is accompanied by neural process in the
brain, each thought or idea having its specific neural
correlate, or, in the language of Huxley, every psychosis
is definitely correlated with a neurosis " (Professor William
McDougall). Now, whatever view may be taken of the
relation between body and mind, it is clear, as Professor
Lloyd Morgan has put the argument, that if the complex
molecular vibrations of the brain have developed from the
simpler molecular vibrations of the ovum, the complex
states of consciousness associated with the former must
have evolved from the simpler states of infra-consciousness,
~ 226

MENTAL EVOLUTION

227

if we may so call them, associated with the latter. Even
such a stout defender of the soul (in the metaphysical
sense) as Professor McDougall holds it " not improbable
that the experience of each generation modifies m some
degree the psychic constitution of its successors,'* thereby
assuming an evolution of the hypothetical soul, though on

Lamarckian lines.

We shaU find in the following that we can trace a con-
tinuous line of mental development as we gradually ascend
the tree of animal life.

(a) Behaviour of Lower Organisms,
It is only in the last two decades that the psychology of
lower organisms has been the subject of systematic study.
With the advent of Darwinism and the belief m an evolu-
tionary explanation of all problems of life, the pendulum
had swung rather to the other extreme. There was a
tendency, in order to bridge over the gap between the
brute creation and man, to interpret animal behaviour
too much from the anthropomorphic point of view, attnbu-
ting, as, for instance, G. J. Romanes did in his works, to
lower organisms psychic faculties which later researches
have proved to be beyond their natural capacity. ^^

It was Professor J. Loeb who, in his work on The
HeUotropism of Animals" (1890), showed that the move-
ments of lower animals can be accounted for in the same
manner as the movements of plants ; and that therefore
no special psychological factor is needed for the mterpre-
tation of their behaviour. What we have to assume as
the fundamental quahty of the living organism is the
excitability of protoplasm. The Uving organism reacts to
stimuU, which may either come from withm (the general
instabihty of Uving matter due to metabolic changes) or
mav arise from outside influences (mechanical, chemical
StimuU, etc.). In the former case there result what have
been called impulsive or sporadic movements (as, e.g.,
the intra-uterine movements of the embryo) or rhythmical

228 THE FIRST PRINCIPLES OF EVOLUTION

movements (as those of the heart, etc.). In the latter
instance, when an external stimulus strikes the organism,
it responds by a change in its behaviour through a reflex
action — i.e., the sense-impression produced by the stimulus
on the body calls forth directly a motor reaction. Thus,
when in a higher animal a limb is irritated, the impulse,
travelling up along the sensory nerve of the limb to the
spinal cord, is there, as it were, reflected to the motor
nerves of the same limb, which set the appropriate muscles
in motion, withdrawing the Hmb from the source of irrita-
tion. But the term " reflex " is often employed also for
those immediate simple reactions in lower animals where
there is no special nerve tissue for conducting the stimulus,
the undifferentiated protoplasm acting in its stead. Thus,
as we shall see, one-celled organisms react promptly to all
sorts of external stimuli. There is in principle no difference
between these reactions and the reflex reactions of higher
multicellular animals. On the other hand, Loeb has
shown that such simple reactions, though apparently pur-
poseful, can be explained by the same mechanical laws as
the movements of plants, which are generally accounted
for by the changes in tension of the different parts, due to
the incidence of the impinging physical forces. This theory
of tropism has been elaborated by Loeb to a considerable
degree, and it forms the most thoroughgoing mechanistic
interpretation of the psychical phenomena of animal life.

It is well known that plants are subject to the influence
of light, that they have the tendency to grow towards the
light, which reaction of the plant protoplasm is ascribed
to heliotropism. Likewise it has been found that the roots
dip straight into the ground through the influence of
gravity ; geotropism is said to be the cause of the growing
downwards of the roots. Similarly, chemotropism is the
reaction towards chemical stimuli, etc. Now, Loeb was
able to show that the movements of a great many of the
lower animals are mechanically determined, in precisely
the same manner as those of plants, by the direct action of

MENTAL EVOLUTION

229

light, gravity, etc., on the organism. Winged aphides

Ten Ixposed to light, regularly ^-'^V'^r^^hrLrrce
the direction of the light rays and move ^war J the source
of lieht The same can be shown of the caterpillars ot
PortUa chrysorrMa, the imagos of fUes^ and other animalj
They are all positively heUotropic. The larva of ihes. ol
iV+ain beetles etc . on the other hand, turn away from
ShTht^JhSa:: n;gatively hd^^^^^^^^ The heho^c^sm
varies not only according to the <^«"dition of the a^imak^
but also during difierent periods of their hves. Thus the
Sove^entioned caterpiHars of PoHhe^a are positively
heliotropic only after their emergence and before their
first feed ; bees only during their nuptial flight, etc. Ac-
Sing to Loeb, the precise method of this reachon is the
followhig: He assumes a specific sensibihty of the body-
tSr"o the chemical action of light. This chemical sensi-
bSy is identical for symmetrical parts of the body. Now.
Til light, striking' a symmetrically built, posijvely
heUotropk organism, is stronger on one side, he photo-
cheLa? reaction on that side is greater, an mcrease in
the^nsion of the muscles of that side takes place, and the
omiism turns its head towards the light. As soon as its
mS plane comes to coincide with the direction of the
iS iys. the incidence of the Ught once more becomes
equal on both sides of the animal, and movement takes
pkce in a straight line. With negatively hehotropic
Smairthe tension is the reverse, the animal turnmg from

*^ln fhis way Loeb would explain many simple instincts in
animals, even as high up in the organic ^^l^^^^^^^^^;
and mice These, though often descnbed as purposeful, are,
accoSg to this theoil, merely the result of a mechanica
reaction between organism and environment. That, for
SSTce, so many animals hide themsel^^s m cranmes a„^
holes is, as Loeb has demonstrated, not due to their desire
fo7coW;alment , but is simply a phenomena of stereot^^^^^^^^
which induces these organisms to seek close contact with

230 THE FIRST PRINCIPLES OF EVOLUTION

solid bodies. It is chemotropism which attracts the fly
to lay its eggs on decaying meat ; while geotropism forces
the butterfly to place itseH vertically for taking wing as
t-sj-;.. soon as it emerges from its cocoon.

v*.^ The moth, too, is drawn to the
light, not by curiosity, as Romanes
still had it, but by positive helio-
tropism. Tropisms, though often
useful for the animal, do not always
work out to its benefit (instance
the moth). There is no original
purposive aim in animal actions,
though it is clear that those re-
actions that proved to be harmful
were gradually weeded out by
natural selection.

Lately these mechanistic theories
have received a decided check by
the investigations of Prof. H. S.
Jennings on "The Behavior of
Lower Organisms'* {1906). By his
beautiful, painstaking researches on
the actions of unicellular organisms
(bacteria, amoebae, infusorians, etc.)
he has come to the conclusion
that even the lowest living beings
show a behaviour which he has
characterized as that of "trial
and error." He demonstrates that
every organism has its specific

Fig. 79.— Spiral Path of Paramecium.

The figures i. 2. 3, 4. etc., show the
successive positions occupied. Ine
t dotted areas with small arrows show the
currents of water drawn from in front.

{From "Behavior of Lower Organisms" by H. S.
Jennings. By permission of the Columbia Universtty
Press.)

MENTAL EVOLUTION

231

,/9*8«*«^

"action system ■•—».«., it performs a certam definite
set of movements under aU conditions of existence.
Thus for instance, Paramecium, a mmute mfusonan,
performsby means of its cilia a forward (or backward) move-
ment, a rotation around its long axis and a swmgmg of
its oral end in a circle, whereby it normally pursues a spural
course (see Fig. 79)- Now it responds negatively by an
" avoiding reaction," whenever it gets into conditions away
from the optimum of its existence. It reacts by movmg
backwards and swerving its oral end in a circle, whereupon-
it resumes its normal spiral forward movtment,which thus
leads it into a new direction (see Fig. 80). The more
pronounced the avoiding reaction, the larger the c^cle
described and the greater the deviation from the onguial
path Thus, by successively trying various durections, the
animal ultimately manages to escape the injurious agent
Jennings holds that this is the type of behaviour of all
lower animals. Various positions are tried (by changmg
the extent of the avoiding reaction), and the one is
ultimately " selected " which brings the organism out of
reach of the stimulation. Fig. 81 shows the movements
of Euglena viridis, a unicellular flageUate, when onentatmg
itself by a " positive reaction " towards a source of hght.

Whether these reactions can really be put on a par with
the method of " trial and error " of higher animals is, to
say the least, doubtful. It is true there is a vanation of
movements ; but is it a selection, i.e., a choice m the real
meaning of the word ? G. Bohn, taking up Loeb s theory,
has tried to show that these phenomena may well be ex-
plained on a mechanistic principle by attributing to lower
organisms "differential sensibiUty" towards the vanous
stimuli. The organism is not only able to onent itself
by tropism according to the direction of the source of
stimulation, but can respond to a change tn the tntenstty
of stimulation by an alteration of its course. Tropism plus
differential sensibility is all that is required m order to
determine these movements, without calling to aid any

»■» II itmrnii'mm

MENTAL EVOLUTION

233

V.-.-.-

Fig. 80. — Diagrams of Avoiding Reactions of Paramecium.

A is a. solid body or other source of stimulation ; / shows the backward movement,
followed by a forward movement in different direction ; // and /// show the
swerving of the oral end in a circle, which is larger in ///.representing a more
_pronounced avoiding reaction ; i, 2, 3, 4, etc., successive po^Jtions occupied.

{From " Behavior 0/ Lowa Organisms," by H. S. Jennings. By permission of tht Columbia

Univetsiiy Press.) t

psychical factor whatsoever. Jennings himself has demon-
strated that with Paramecium, for instance, the swerving
of the oral side is more decided the stronger the stimulus.
It would seem, then, that the reaction of these tiny animal-
cules is dependent on the strength of the stimulus, and is
not so much a matter of choice. More to the point would

Fig. 81. — Orientation of Euglena.

The organbm. originally swimming in the direction of i. is suddenly
illuminated by a light indicated by the arrows on the right
It swerves and changes into a succession of directions (mdicated
by 2 to 16). until it finally occupies position 17. directly
towards the light.

(From " Behavior of Lower Organisms;^ by^H.^S.^Jm^^^ By permission of the Columbia

seem his observations on the behaviour of another uni-
cellular organism, the sessile StetUor (see Fig. 82). He
found that, when the same irritant stimulus is appHed over
and over again, the animal does not continue in its mode
of reaction, but modifies it in various ways in order to nd
itself of the undesirable stimulus. Ultimately, if no other
* 30 '

234 THE FIRST PRINCIPLES OF EVOLUTION

procedure succeeds, it breaks away ^^s con^^^^^^^^^
^eeks a new abode. This seems very much like a conscious
rdantadoT of means to ends, and Jennings does not
££ to draw'his conclusion. Looking at the behaviour
nesitatexoui ^^ ^^^^^ organisms from

the psychic point of view,

he sees no fundamental

difference of kind between

the psychic life of unicellular

organisms and that of the higher

animals, including man.

To this we must answer that
in this case we should have
consciousness where, according
to the general consensus of
opinion, it is held to be absent.
A frog deprived of its brain, so
that only the spinal cord is
left, executes appropriate reflex
actions, wiping away with its
leg acid dropped on its side.
It is even able to do this with

Bending over to remain in ^-^e other leg if the first leg is

7^!^l^ -i P»"ed by prevented from moving, though
the experimenter to the ^th seemingly greater aim-
right, culty. Further, we should have
^^"«:«"'Ws''/-^;^'^?^- *^ attribute psychic quahties

^lon of the Colimbia Oniversity ^^ plants alsO, for inSCCtlV-

^''^*-^ orous plants are able to

" discriminate " nicely between various stimuli, reacting
in the appropriate manner only to those that mdicate
digestible food-substances.* We enter here upon the

• It must be remarked that this logical step has actually been
taken by some. PfliSger, for instance, attributed consciousness to

the dec Jpitated frog, and spoke of a ^«^^---^-;;^^,f?l^ ^'j^^,!
SDinal cord). Among botanists we have a similar tendency Pro-
S Francis Darwi^ credits plants with tactile perceptions ; France
even with a " soul and intelligence "

MENTAL EVOLUTION

235

Fig. 82.— Stentor Roeselii.

discussion of the problem of consciousness Wiere d(^s
it begin ? Unless we would adopt the belief that all
matter is endowed with consciousness^a thesis held by
many, and by no means indefensible-consciousness must
have originated at some stage of organic development
But even on the first supposition it is clear as Lloyd
Morgan has pointed out, that we must make a distmction
between consciousness as accompanying mere sentience
and consciousness as a guiding and directing factor-
" effective consciousness," as he calls it. The first may
be assumed as present in all sentient beings. With the latter
we generally credit only such organisms as are able to
•' profit by experience," which presupposes at least a dim
remembrance of the results of previous behaviour. This,
we shaU see, is generaUy held not to occur until a higher
stage of mental evolution has been reached.

(6) Insiincl.
What is instinct ? The conception of instinct depends
to a large extent upon our idea of its origination In pre-
Darwinian times a sharp division was made between the
brute creation, supposed to be endowed with instinct only,
and man, who was guided by reason This Jacile inter-
pretation, which saw life from the static pomt of view-
everything being determined by a final decree of Providence
_h^ had to give way to a more thoroughgoing analysis of
mental phenomena. Instinct, considered froni the evolu-
tionary point of view, is not a special faculty of mmd : it is
merely the psychic expression of the structural orgamzahon,
which, like the anatomical traits, tends towards the well-
being of the individual and the preservation of the species.
Indeed, in one sense it may be looked upon, in Bergson s
expression, as nothing more than " a prolongation of the
Jrk of organization." In so far it acts mechanically,
being dependent on the inherited structure of the organism,
and ha-dng no conscious knowledge of its own purpose.
In fact this type of instinctive behaviour can well be

236 THE FIRST PRINCIPLES OF EVOLUTION

described in Spencer^s phrase as " compound reflex action."
Just as in the simple reflex a given stimulus produces a
definite reaction, so here a mechanical sequence of move-
ments is set in train with predetermined uniformity, so
that the individual is unable to deviate from it. Thus,
to quote from Romanes : " P. Huber has described a cater-
pillar which makes by a succession of processes a very
complicated hammock for its metamorphoses. ... If such
a caterpillar was put into a hammock partially finished,
far from feeling the benefit of this, it was much embarrassed
and even forced to go over the already finished work,
starting from that stage which it had left off before it
could complete its own hammock. So, again, the hive-bee,
in the construction of its comb, seems compelled to follow
an invariable order of work."

But such " chain-reflexes," where one step determines
the next, do not exhaust the essence of true instinct. While
the mechanical kind of instinct is unalterably fixed by
external conditions, a more adaptable type of action
arises when the inner organic factors— namely, the internal
physiological state of the organism as a whole — take a part
in determining the eflect of a given stimulus. It is a
commonplace observation that a hungry animal reacts
towards food differently from a sated one. In other words,
the " setting " of the organism, as Professor L. T. Hobhouse
has called it, has a decided influence on the ultimate
reaction of the individual to its environment. It implies
a certain plasticity of instinct, giving the first step in the
adaptability of instinctive behaviour in animals.

Thus we pass insensibly from a rigid reflex response to an
adjustable type of instinctive action. How far this adap-
tability extends is a matter of degree. While in " pure "
instinct the series of actions is prescribed within the limits
of hereditary organization, each stage determining the
next (subject to the physiological condition of the organism),
we find in other cases that the response to specific stimuli
may_be less rigidly circumscribed. Though the general

MENTAL EVOLUTION

237

plan of the whole instinctive action is fixed by the internal
impulse, the steps towards carrying it out are left, to a
certain extent, to individual adaptation according to cir-
cumstances. It is here that the first dawn of intelligent
behaviour arises within the precincts of instinct. While
instinct is prior to all individual experience, working blindly
towards an end, intelligence takes note of the means to-
wards achieving that end. That instinctive behaviour
may be subject to individual intelligent modification
within fairly wide Hmits has been proved for many animals
as low in the scale as insects. The old-fashioned sharp
division between instinctive action (of which the insects
used to be taken as a type) and rational behaviour has
become untenable.

Another feature of a similar nature must be noted here.
Just as the response to specific stimulation gradually
loses its rigidity with regard to the action of the adult
individual, so we see a parallel widening of the basis of
behaviour in the young. In lower organisms — in wasps,
for instance — the whole train of biological action is pre-
determined within narrow lines from the very beginning of
existence. In higher animals, such as the chick, and much
more in the human infant, we find no such definiteness
of inborn instincts. What is inherited in these cases is a
general instinctive impulse, not instinctive knowledge.
The chick pecks instinctively at small, especially at moving,
objects ; but it pecks at first as readily at a stone as at a
morsel of food. It is only individual experience that
teaches it to discriminate between them. This circum-
stance would seem to tell rather against the chick. But,
as Lloyd Morgan has pointed out, in higher animals parental
guidance is able to take the place of much of the instinctive
regulation among lower creatures.

Coming now to the question of the origin of instinct, we
have already seen that Herbert Spencer explained it as a
combination • of reflexes, knit together into one complex
action through the accumulated experience of successive

' *.,

\ 1

238 THE FIRST PRINCIPLES OF EVOLUTION

generations. This implies that the effects of individual
experience are wrought into the biological inheritance of
the race. Indeed, there exist, as has been expounded in a
previous chapter, two rival camps among evolutionists.
The Lamarckists, believing in the inheritance of acquired
characters, look upon instincts as inherited habits, which
were originally acquired by the individual and handed down
to the offspring. This would justify G. H. Lewes's con-
tention that instinct is " lapsed intelligence.'* Professor
Wundt has distinguished two classes of instinctive acts :
those which are acquired by the individual during his life-
time, and those which are connate — i.e., inborn in the
individual. The latter he assumed to be due to the trans-
mission of individually acquired habits.* Romanes, fol-
lowing Darwin, admitted a twofold genesis of instincts, by
use-inheritance and by natural selection, leading to primary
instincts in the latter more important case and to secondary
instincts in the former ; while a combination of both
factors produced blended instincts. The main argument
against the Lamarckian origin of instinct lies in the fact,
so often noticed, that the inheritance of acquired characters
is so far non-proven. If all instinct were lapsed intelligence,
we should find the more intelligence the lower we go in the
animal scale, which is certainly not borne out by facts.

The most generally accepted theory of the evolution of
instincts is based on natural selection, as originally pro-
pounded by Charles Darwin. Instincts vary in the different
members of the same species in like manner as bodily
structures. It is by the constant selection of the most
adaptive variations — those that serve the biological end
of the race in the greatest degree — that instincts were
gradually perfected and evolved into a more and more
complex type.

Before leaving this subject we must not omit to mention

• In order to avoid confusion, it would be better, as Lloyd Morgan
points out, to denote the former {i.e., the so-called acquired instincts)
as habits, and not as instincts.

MENTAL EVOLUTION

239

the latest hypothesis of instinct, enunciated by Professor
Henri Bergson. According to him, " the cardinal error is
to see in vegetative, instinctive, and rational life three
successive degrees of the development of one and the same
tendency, whereas they are three divergent directions of
an activity that has spUt up as it grew." The different
tendencies separate out, as it were, though mcompletely,
from the common magma of the original impetus of hie,
each pursuing its own course. Though there is " no mtelh-
gence in which some traces of instinct are not to be di^
covered, more especiaUy no instinct that is not surrounded
with a fringe of intelligence/' these are in reaUty '| two
developments of one and the same principle," bemg " two
divergent modes of knowledge." Instinct itself Bergson
defines as "sympathy (in the etymological sense of the
word)." He assumes that one species possesses an instmc-
tive knowledge of another on a particular point, simply
because both species must be considered as " two activi-
ties " having their common root in the fundamental unity
of Hfe. He quotes as an instance the marvellous exactitude
with which certain wasps paralyze their prey, without
kiUing it, by stinging it just at the nerve-centres, however
many there be. This procedure keeps the victims, which
have to serve as food for the next generation, motionless,
yet free from putrefaction. It has, however, recently been
shown, by the classic investigations of Dr. and Mrs. Peckham
on wasps, that the stinging mstinct is by no means so un-
erring as was supposed. The victim is often killed, while
the larvse do not seem to suffer by partaking of decaying
food. Bergson tries to make Hght of this objection. He
points out how inconceivable it is that the wasps could
have tentatively acquired the necessary anatomical know-
ledge, and have gradually perfected it by hereditary trans-
mission. On the other hand, he rejects Neo-Darwimsm
as being too much a theory of chance.

Bergson's own explanation, however, breaks down, on
Professor Poulton's showing, as soon as we take a large

240 THE FIRST PRINCIPLES OF EVOLUTION

enough survey of the working of animal instincts as a
whole. The supposed sympathy is non-apparent where we
should most expect it. That the maternal instinct of a bird
should fail, as has been observed, to lead it to recognize
its own young as soon as this is placed a little distance
from the nest, is certainly a proof that no mysterious
sympathy is at work between parent and offspring. The
innumerable cases where complicated arrangements are
made for the laying of eggs, the weaving of cocoons, etc., in
order to achieve the proper hatching of the young, can also
not be based on sympathy, for here the parents never see
their young. Nor can the phenomena of mimicry be due
to this cause ; while the supposition of a continuous selec-
tion of the most adaptive types still remains the best
solution of the problem.

As regards Bergson's view that there are two divergent
lines of mental evolution — that of instinct, represented
mainly by the insects, and that of intelligence, leading
through the vertebrata to its culminating-point in man —
we must point out that Professor McDougall has shown,
in his " Social Psychology," that the main social character-
istics of man are based on instincts which have been
inherited from his animal ancestry. Indeed, according to
this view, " the instincts are the prime movers of all human
activity," " and all the complex intellectual apparatus of
the most highly developed mind is but the instrument
by which these [instinctive] impulses seek their satis-
factions." And this opinion stands by no means alone.

We have seen that intelligence arises gradually in the
domain of instinct. While all instinctive behaviour is
" prior to experience," being the automatic expression of
the inherited organization, intelligence consists in the
ability of the individual to " perform acts in special adap-
tation to new circumstances." It thus involves an element
"of choice, which is based on the method of '* trial and

MENTAL EVOLUTION

24T

error," whereby the organism is enabled to profit by its
own experience.

The first step in the elaboration of intelligence is reached
when, as already adverted to, the instinctive behaviour of
the organism, instead of being rigidly determined in all its
particulars, is fixed, as it were, only in general outline. It
becomes gradually defined by individual adjustments of the
organism, which shape its action in accordance with the re-
quirements of the surroundings. We have already quoted
the case of the pecking instinct of the chick. The newly
hatched bird does not, in the first instance, discriminate be-
tween eatable and uneatable objects. But having pecked at
a nauseous Cinnabar larva, let us say, it learns to avoid it
in the future. What exactly is the process of rejection ?
The actual mode of learning is, according to Professor Hob-
house, the following : At the first trial there occurs in the
chick a succession of reactions, which can be written down
as : stimulus— pecking— unpleasant taste— rejection. After
the first experience the same stimulus comes to elicit the
movement of rejection without the intermediate stages.
The chick may be seen to run on the first impulse towards
the distasteful morsel, but soon checks itself, wiping its
bill as though it had tasted it. The excitement aroused
by the stimulus becomes coupled with the character of
another excitement, which it has previously brought about
(here the rejection movement), so that the second now
follows the first automatically. This process is called
"assimilation." In this way instinctive tendencies are
either inhibited or reinforced by acquired habits.

We can now go a step further. Not only may instinctive
reactions be modified by the effect of experience, but new
reactions, towards which there was no original tendency,
may be acquired by the same means. Thus fish can be
taught to come to be fed by their keeper. According to
recent ideas of comparative psychology, we cannot
attribute to the fish any distinct appreciation of the rela-
tionship between food and keeper. There is rather formed

1 -I

M
-J

242 THE FIRST PRINCIPLES OF EVOLUTION

a regular association between two excitations, the going
forward for the food and the sight of the keeper, so that the
latter is absorbed into the character of the former. There
is no conscious knowledge ; but food and keeper become
associated in the animal's mind, not as two abstract ideas,
but as two perceptions— namely, the going after the food
and the seeing of the keeper. Intellectual behaviour at
this stage, then, is due to " impulse/' as Dr. Thorndike has
termed it--t.^., to the direct feeUng of doing as distinguished
from the idea of the act done.

In this manner must be explained intelligent action in
the various classes of lower organisms. How far down such
intelligence reaches it is difficult to tell. There is a good
deal of difference, not only between species of the same
class, but even among individuals of the same species
One can only indicate approximately the average level of
intelligence attained on the whole within any one class.
According to this standard, the lowest animals to whom
intelligence can be attributed are the worms (earthworms),
though it has been doubted even here. Limpets and snails
are said to be able to return to their home ; in this case
they must be credited with some perception of their locahty.
Higher up in the scale we find ample evidence of intelligent
modification of instinctive behaviour among insects,
especially bees, wasps, ants, etc. We shall only mention
what may be considered the most far-reaching extension
of the use of tools. Dr. Peckham pictures a solitary wasp
using a stone to beat down the earth over its nest (see
Fig. 83). The same mode of mental procedure is still
predominant as high as the fishes.

Ascending somewhat higher in the scale of mental
evolution, we find no essential change in the process of
intelligent adjustment, but rather an extension thereof.
The method is still one of direct correlation between sense-
impression and motor reaction, but this relation, instead
of holding good only for one particular sequence can now be
" varied within certain Hmits, thereby enlarging the scope

MENTAL EVOLUTION

243

of intellectual adaptation. The second term of the relation
may be represented by any object of perception, instead of
by a particular one. Thus a dog which accommodates itself
always to one particular place, may do so by habituation
—i.e., by the process of assimilation previously described.
But if the dog is able to find its way about in some other
home, it must be able to substitute one perception for
another, and must therefore be credited with memory
and the idea of the object. In other words, it wiU be able
to form generic instead of particular images. It has an

PiG^ 83. — Wasp using Stone.
(From " Animal Behaviour^' by C. Uoyd Morgan.)

idea of locality in general, and not of one particular place
only. But, it must be understood, such ideas are only
practical ideas. The inference drawn remains still within
the domain of sense-experience— that is, it is not made
in the manner of an abstract thought, but is rather impUed
in the action of the animal. Professor Hobhouse has
called this stage of mental development practical or per-
ceptual judgment. It enables animals of the type of dog,
cat, etc., to form practical ideas of objects in general, of
locaUty, persons, etc. They are capable of apprehending

244 THE FIRST PRINCIPLES OF EVOLUTION

the relations of difEerent parts in their surroundings, and can
learn by perception of the results obtained, though they
cannot teU the why or wherefore of their action.

We must note^ however, that this view, which can claim
experimental evidence in its favour, is not completely
shared by other psychologists. Thus, Dr. Thomdike, who
made a series of observations on cats and other animals,
came to the conclusion that what is involved in the process
of learning is merely a direct linking together of sensory
images by the process of assimilation. Out of a succession
of random movements the animal chances on the right
action. By the method of trial and error " gradually all
the other non-successful impulses will be stamped out, and
the particular impulse leading to the successful act will be
stamped in by the resulting pleasure." Thus a cat enabled
to escape from a specially prepared box by pulhng a cord,
for instance, first hits upon the appropriate movement by
chance. The sensation of escape being repeatedly coupled
with the pulling of the string, both acts become finally
worked into an habitual sequence. Both explanations
given above agree in principle : behaviour at this stage of
mental evolution is not based on rational thought, but on
perceptual association.

Higher up in the scale of the animal series there takes place,
as Professor Hobhouse has put it, " an increase in the
elaboration and articulation of ' practical ideas ' " witnessed
at the lower stage. Monkeys manage to manipulate sticks
and other tools with precision, and are able to learn by
" reflective imitation," in which the act of another, which
produced no direct result to the observing animal, is by it
copied and applied to its own ends."

{dj Reason,

" The vast interval which separates human achieve-
ments, so far as they depend on human intelUgence, from
animal achievements; so far as they depend on animal
"intelligence, is connected with the distinction between

MENTAL EVOLUTION

245

perceptual and ideational P-^"^^ t^^™:; ^tSeS
either purely perceptual, or. m so far ^ |Jf "^J^^^^^ ^^ its

these ideas serve ong'^to Pro^t ^^ ^^^^^ . ^

actual execution. On the otner naa , ^ ^j^^^

his head,' by means of trams of f^'^^^'^^nsclvMe of
before he begins to cany them out. He is^hus cap

overcoming difficulties m ^^^^f^rfroTk Stolt

?hat of man in the clearest PO^^^^j;£,\;^'!^' les.
animal makes use of genenc images ^f P'^^^^^^^^Xnce
man is capable of analyzing J-f^l^ S^ual
apart from the perception of the "^™ brings into

Uer concrete objects come tost^d^fo^^J^^^^^^
raoable of recombmation. U is tne wui

be detached from its object, so that it may serve
abstract symbol. i„„„,a„p ? It is well

There is great doubt whether animals are able to com

rf''-"*""'"*--'"'

246 THE FIRST PRINCIPLES OF EVOLUTION

municate complex facts to each other, since they have no
power of description. All accounts of such feats resolve
themselves into suggestion of the appropriate movements,
on the principle of " foUow-my-leader." Even where words
are understood by lower animals, their sounds simply
serve as signs, carrying no more content than perhaps the
implication of a whip.

Language in the proper sense of the term— human lan-
guage— first arose when a concept severed from its imme-
diate complex was called by a distinctive name. It is
impossible at present to say when and how this decisive
occurrence took place,* though it may be taken for granted
with Lloyd Morgan that the lower modes of interconi-
munication among animals, based on instinct and intelli-
gence, furnished the necessary steps. Infant psychology,
interpreted on the evolutionary principle, is in total agree-
ment with such an assumption. The human infant, at first
only uttering emotional cries, gradually attains the stage
of the word-reflex, when a word is used as a mere exclama-
tion, from whence it passes to the word-sentence, using the
single word as a description of fact (e.g., " hot " for '* milk
is hot "). The formation of proper articulate sentences

follows apace.

It is the combination of reflective thought with de-
scriptive language which raises humanity so high above
its nearest congeners. We need hardly dwell on the
further elaboration of the ideational process, its systemati-
zation into science, its flight into the fields of imagination
and philosophy. By making possible for the first time the
development of a self-conscious ego, capable not only of
reflecting on its own self, but also on that of its neighbour,
it paves the way for all the higher attainments of ethics
and aesthetics.

♦ Mr. S. S. Buckman suggests that the emotional sound (e.g.,
"ma"), being coupled in association with a particular object of
sense-experience (here the mother attending to the child), ulti-
mately comes to stand for the object itself.

MORAL EVOLUTION 247

2. Moral Evolution.
How far does the developmental hypothesis apply to

''Sere, too, as in so many fields, the theory oi evolution
has produced a profound change, replacing the old static
morality, decreed unto all men for all tmie by the more
rational idea of a continuous development of moral ideals
and social customs. But though the view of a progre^^ve
morality has been generally accepted, there is stiU as in
pre-evolutionary times, on the fundamental question of
morals an irreconcilable opposition between the two
modern schools of ethical thought. Professor Sorley has
pointed out that we must be careful to distmguish the
"evolution of ethics" from the "ethics of evolution.
While the former traces the gradual change of the moral
sentiments throughout the ages, the latter mvolves a
moral valuation of human action, and endeavours to find
a standard of conduct. Now, it may be admitted that
the evolutionary school, deaUng more with the question
of moral progress than with that of moral worth, has so
far not been able to give an entirely satisfactory answer
to the latter problem. But the two sides of ethical theory
are by no means irrelevant to each other. The criterion
of the ethical standard, as given by the evolutionists, is
to a great extent dependent on their view of its genesis ;
while it would seem that the modern intuitive school is
led to assume a supernatural origin of the moral sense in
man, largely through its belief in an immaterial spiritual

"^ Our main question to decide is : Can the moral instinct
of man be traced back to his animal ancestry? Ihe
intuitionists stoutly deny this. For them conscience is a
. The chief representatives of the modem metaphj-sical (ideaUst)
scho^ in Engird are Thomas Hill '^'^^JJ^^^^ *°
Ethics "). and James Martineau (" Types of Ethical Theory ).

I (I

248 THE FIRST PRINCIPLES OF EVOLUTION

special faculty of man, speaking with an unerring voice,
which can only be understood as an integral part of
man's divine heritage. According to this view, there Ues
a whole world of difference between the moral feeUngs
of man and the anunal desires of lower creatures. It is
not here our business to criticize this theory in detail.
It must suffice, in order to clear the ground for the evolu-
tionary view of ethics, to adduce the main arguments

against it.

In the first mstance, it must be pointed out that there
is no reason for separating the ethical judgments of
man from his rational judgments, and ascribing them to
special moral sense, revealing intuitively what is right
and what is wrong. We shall find that the progress of
morality in man is bound up to a large degree with his
mental and social development, and can only be inter-
preted on this basis. Besides this, a metaphysical theory
of ethics, as Professor Sorley has pointed out, " sunply
brings forward a new difficulty— that of understanding
how the temporal process in which human morality is
developed can be related to a reality which is defined as
out of tune or eternal." Furthermore, a review of the
customs and beUefs of different ages and countries shows
so many inconsistencies and vagaries that it would be
futile trying to find an absolute guide for right conduct.
Professor Sorley, himself a not unsympathetic critic of the
ideaUst school, has shown that the attempt to call in a
metaphysical principle to account for the moral ideal m
man has failed no less than that of the evolutionists.
There is, therefore, on this ground no further reason to
hold to a supernatural origin of the moral sentiments ;
and we must try, in accordance with the general trend of
evolutionary ideas, to trace the conduct of man to its
primitive animal source. That this may be possible is
not denied, even by those who look upon this task as
still unfulfilled. Says Mr. A. E. Taylor, in his " Problem
of Conduct " : " That animal behaviour, if closely studied

MORAL EVOLUTION

249

by competent psychologists, would present us wi h the
aUo^a oi morality, it is only reasonable to beheve
Sa%, we see every time in the moral growth of any child
that etkical notions arise only slowly by a gradual process

of mental elaboration. , ,

We shall give in the following, first an account of the
animal origins of morality, so far as worked out, and then
the later human developments.

(a) Animal Origins.
Ethical conduct cannot be identified exclusively with
altmistic behaviour, as some have tried to show but
conSsts rather in a harmonious adjustment between
selfish and unselfish action. Still, for the purpose of
tracing the moral sentiments back to the|r primitive sub-
human' beginnings, we have mainly to consider Je deve^p-
ment of the sympathetic emotions. It is these wliich
« with ever greater strength during the course of
Toraf evolution, gradually subordinatmg ^he f msh im-
puTses and desires to a higher end. As a matter of fact
dater becomes the conscious attitude of sympathy is
TriginaUy nothingbut an instinctive action, performed in the
eSse of animal function. Just as self-preservation bids
the organism to use all its powers towards complete mdi-
Sua?sa isfaction, so it is part of thk satisfaction to
Sdulge in the procreative instinct, which tends to further
Ihe We oi the species. It is at this stage quite mipossible
to dScriminate between self-regarding and other-regardmg
actions, such difference arising only slowly with the simul-
taneous increase in the depth and extent of sympathetic

'"it'S" Darwin who. in the " Descent of Man ;• insisted
upon the contmuity of the physical and psychical sides
orhuman nature, knd for the first time ried to reduce
Se Zral feelings of man to their prmutive biological
demSs As such must be considered the parental and
£ affections and the social instinct, as witnessed m

250 THE FIRST PRINCIPLES OF EVOLUTION

animals. Mr. A. Sutherland has elaborated this thesis
at great length, showing how the act of bearing and rearing
the young becomes at once more prolonged and compli-
cated as we ascend the animal scale. With the lowest
organisms propagation is merely a physical process, the
germ-cells being voided outside the body. Their fertili-
zation and development is left entirely to chance. Only
slowly are means evolved by which a more direct con-
tact between ovum and spermatozoon is secured for the
purpose of fertilization, until, finally, the male semen is
deposited within the female, where the process of fertili-
zation takes place with a mmimum of waste. But the
fertilized product, the egg, which now receives a shell,
is still hatched outside the maternal body, bemg greatly
exposed to the dangers of destruction. At this stage,
which reaches its highest development among birds, the
young akeady receive a great deal of attention from the
parent. We need only mention the familiar spectacle of
the hen and her little brood. Further progress takes place
by lengthening the time of embryonic development, which
now goes on within the mother, and leads to the birth
of living young, as in the mammals, though early examples
occur in some viviparous fish and reptiles.

Meanwhile, there has appeared in birds— apart from
faint traces in a few fish— the first definite instance of
family life, whereby the male parent is drawn into the
widening circle of sympathetic relationship. The higher
we ascend, the more prolonged becomes the period of
gestation, and the greater is the relative immaturity and
helplessness of the newly born offspring. The assiduous
care of both parents is now needed in order to prepare
the young for their future task ; and thus is laid the first
animal foundation of later marital Hfe. For with the con-
tinuous increase of the period during which the members
of the family are held together, more and more scope is
given for the rise of conjugal affection, which ultimately,
with the establishment of the permanent family group,

MORAL EVOLUTION

251

becomes one of the most important factors of moral

progress.

All the steps so far sketched in the gradual building-up
of the sympathetic emotions have most probably been
attained by means of natural selection. We must re-
member that in the lower organisms the waste of germs
that never come to maturity is appalling. Gradually a
great saving of energy is effected for the individual by
its producing less offspring, though the needs of the species
are still fulfilled by substituting for the prodigality of
lower animals the greater protection of the young among
higher beings. The more advanced species would thus
have an advantage and be fostered by natural selection.

So far, we have seen the sympathetic emotions limited
to the parental pair and their immediate offspring. But
another factor appears by which the community of feelings
is extended beyond these confines. Sociability is a dis-
tinctive feature of all gregarious animals. Many species
aggregate in large numbers, and it has been observed that
the members of such herds are rendered most miserable
when isolated from the main body. "The feeling of
pleasure from society,*' says Darwin, "is probably an
extension of the parental and filial affections, since the
social instinct seems to be developed by the young re-
maining long with their parents ; and this extension may
be attributed in part to habit, but chiefly to natural
selection." Co-operation and mutual aid are of conunon
occurrence among animals. Apart from the merely in-
stinctively automatic behaviour of insect communities, we
have many higher species showing considerable foresight
in adopting means for mutual defence. Thus, the uttering
of warning cries, posting of sentinels, submission to the
leadership of the strongest male, etc., are mentioned by
Darwin, as also the hunting in packs for the purpose of
concerted attacks. Prince Kropotkin, in his "Mutual
Aid," looks upon co-operation as the chief factor in the
evolutionary process. But this can hardly be main-

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252 THE FIRST PRINCIPLES OF EVOLUTION

tained, seeing that unsociable species are holding their
own not less successfully. It is among weak species that
the social instinct has been evolved, by which they have
been enabled to survive in the struggle for life.

If conduct be defined, with Herbert Spencer, as '* the
adjustment of acts to ends," it follows that the evolution
of conduct will consist in a continuous improvement of
such adjustment, leading to a prolongation and furtherance
of life. But we have seen that, with the ascent in the
animal scale, the field of emotions gradually widens, em-
bracing first the progeny, then the mate and family, and,
finally, the fellow-members of the race. The consecutive
stages in the development of conduct, then, imply a corre-
sponding satisfaction of the various feelings connected
with the procreative and social instincts, thwarting of
these natural impulses leading to a feeling of pain and
distress. Now, we call those actions " moral " which
involve a consideration of others as well as of oneself.
We see, therefore, that ethical conduct coincides with more
highly evolved conduct in the Spencerian sense, the highest
conduct being that which leads to a perfect life, not
only in maintaining individual life and rearing new
individuals, but also in aiding one's fellows in the
attainment of this end.

According to this theory, it is the pleasurable emotions
connected with certain actions which lead to the survival of
the species possessing them ; for the wider the sympathies
of the individual, the greater, on the whole, the chances
of success in the struggle for existence. It is evident that
this must be so. For if pleasurable feelings were aroused
by hurtful conditions, the animal reacting thus would
soon be exterminated. A gregarious animal persistently
straying widely from the main herd runs great risk of
meeting premature death from its enemies. The pleasur-
able, then, becomes the useful to the species at large. As
Lloyd Morgan puts it : " The two ends agree — the psycho-
logical end of the attainment of pleasure and the avoidance

MORAL EVOLUTION

253

of pain, and the biological end of race preservation."
U has {,een objected to this theory that pleasure c^^^^^
be and, in fact, is not the real end of hfe. What the
organism aims at, is not pleasure but action m fumhnent
of its organic requirements. Impulse is the prmiary
motive. But since pleasurable actions ^^^^^J^' J^^^^^^^^
whole, with useful actions, and pamfu with harniful
actions, pleasures and pains, though not the ends of hfe,
serve as its most immediate guides.

Now, it cannot be said that animals are capable of
ethical ideas in the real sense ; for we have seen in the
previous chapter that animals do not get beyond the p^r-
ceptual stage of thought, while mordity proper is only
possible on the ideational plane reached by man. But
to use the language of Lloyd Morgan, pleasure and satis-
faction attending particular situations contain the per-
ceptual germs of what becomes, through reflection in
man! ethical approbation. . . . The satisfaction or dis-
satisfaction arising from the performance or non-per-
formance of instinctive behaviour, evolved for the bio-
logical end of the preservation of the social community,
is the perceptual embryo from which conscience is de-

""^The^origination of conscience and the development of
moral ideals is our next problem.

(6) Human Developments.
The principal aim of all ethical inquiry is to find a
criterion of moral worth. How does ^t/^ome about that
man caUs certain acts good and others ^^^-'r'-'^^^
forms moral judgments of approval and d sapproval
Feelings of pleasure and pain cannot be ^^^^ectly identified
with ethical conceptions of right and wrong. We have to
construct a bridge between the non-moral sensuous ex-
periences of animals and the moral sentiments of man
- Moral judgments," as Professor Westermarck has pointed
out " could never have been pronounced unless there

254 THE FIRST PRINCIPLES OF EVOLUTION

had been moral emotions antecedent to them." Such
moral emotions must, he says, be traced back to animal
feelings of a non-moral character. He would relate moral
disapproval or indignation to the impulse of anger and
revenge in animals, while moral approval has its non-
ethical source in the " retributive kindly emotion," as
evidenced in the sympathetic feelings of gregarious beings.
These animal emotions have their distinctive biological
value, for resentment serves as a means of averting un-
pleasurable feelings, and therefore danger ; while sociability,
of course, secures positive benefits.

The question now is : How does the merely instinctive
reaction of brutish behaviour evolve into the consciously
moral attitude of man ?

The change is made possible only by the attainment of man
to the ideational level, where there exists conscious reflection ,
memory, and expectation, and therewith the possibility of
contrasting experience as it is, with experience as it might
be, or ought to be. It was, as Darwin already indicated,
through comparison of one's own deeds with the knowledge
of ** what others consider as praiseworthy or blameable "
that human conscience was developed. In other words,
the sense of obligation becomes a fact only in conjunction
with and through the rise of tribal feelings. Elation and
dissatisfaction of a non-ethical kind may be observed in
animals. Failure to catch its prey may lead an animal
to " brood "; cats have been known to chastise their
kittens for uncleanliness. The same pro-ethical sentiment
may be found in the childlike savage who sulks over a
disappointment. It is when tribal opinion makes itself
felt upon, and is anticipated by, the individual, that non-
moral dissatisfaction turns into a sense of moral obligation.
As A. E. Taylor puts it : " We pass from mere feeling of
what might have been to the feeling of what is expected
from us." Social custom, most rigid in the tribal stage of
human society, imposes itself as an inviolable rule of
conduct on all members of the community.

MOREL EVOLUTION

255

With this we have reached what may be considered the
basis of real ethical feeling in man. Actions are now per-
formed not only in response to an inner mipulse, but m
conformity to an external rule. But such moral sentmients,
so far as they exist at this stage, are not based on any
sound generalization of right and wrong. For the savage,
conflned withm the narrow limits of his mental experience,
and imbued with the beUef in magical powers and evil
spirits very much akin to himself, moral obUgatnn is
confined to the relations within his own class. Such
'' group morality " is of a crude sort, being limited to an
unreflective kind of behaviour, as dictated by the actual
exigencies of the tribal life of primitive man. The ethical
sentiment proper has hardly yet arisen into full conscious-
ness Actions are not committed or omitted because they
are deemed moral or immoral, but because they are sup-
posed to lead to pleasant or unpleasant consequences to
oneself. To quote Professor Hobhouse : " Moral feehng
is not at this stage disengaged from a prudential dread of
human vengeance or of mysterious forces in which there
is nothing peculiarly moral."

Ethical progress does not consist so much m an actuaJ
improvement of the moral instinct as in a " rationalization
of the moral code." It proceeds pari passu with the
development of human ideas. With the rise of a rehgious
consciousness and the behef in a spiritual Deity, ethics,
too, is transformed, being deepened in its content and
extended in its scope. For as the conception of the God-
head gradually attains a more ethereal and subUme aspect,
leading finally to an immaterial universal Divine entity,
so conduct, viewed m the hght of reUgious sanctions, be-
comes more and more ideal. The source of obligation
is now derived from a spiritual authority, and thus becomes
supernatural. At the same time, the gospel of love, as
preached by the great ethical religions of the world, has
helped to widen " the boundaries of the moral conmiunity,
breaking down by degrees the walls of tribal and racial

256 THE FIRST PRINCIPLES OF EVOLUTION

prejudice, and tending to weld together all human kind
into one brotherhood ; though, be it said, this process has
by no means yet reached its final goal.

But the story of moral evolution does not end here.
One further step has to be made for the complete rationali-
zation of ethical conduct. Theological ethics still has a
personal tinge of self-interest, in so far as " the belief in
rewards and punishments arbitrarily affixed by the choice
of the Deity to particular forms of conduct " lays the
stress on external sanction, often to the detriment of real
morality. Ceremonial law tends to usurp the place of
moral law, and there is no safeguard as to what religious
fervour may not sanction. The grossest immorality has
been perpetrated in various places and at various times
in the name of the gods.

It was the ancient Greek thinkers who for the first time
sought to found a system of morality on a natural basis
by trying to discover the real essence of human conduct.*
To find an " objective " standard for man's action, de-
rived solely from human experience, and serving as a
rational guide in life, has been the aim of philosophical
ethics ever since. We cannot here go into a discussion
of the various theories worked out in successive ages.
Suffice it to point out the consequences of this movement.
The ethical ideal is now sought entirely within the limits
of man's social relationship. Right and wrong, instead of
being derived from an external authority, are now made
dependent on the good sense and feeling of the individual
himself. *'The sense of obligation has ceased to be a
sense of what is expected of me, and has become a sense
of what I expect of myself" (A. E.Taylor). In contrast
with the tendency towards self-negation under a theo-
logical system, self-realization of the individuality is now
insisted upon in fulfilment of the one great purpose of

• Ethical idealism, as conceived by the ancient Chinese thinkers,
has had no direct bearing on Western civilization, and is. therefore,
here left out of account.

MORAL EVOLUTION

257

existence— the bettennent of the human race. Thus
ethics returns with a fuU consciousness of its own aun
to its pristine beginnings— the life of the species.

The development of human moraUty consists, as ahready
remarked, mainly in an elaboration of the concepts of
ethics. But is there not at the same time an actual
advance in conduct, due to an improved moral sense?
A Sutherland would explain moral progress exclusively
by natural selection, through the survival of the sym-
pathetic and the weeding out of the selfish types. To this
factor may certainly be attributed the rise of pnmitive
social sentiments. It used to be brought as an important
argument against Darwin's theory that it made agamst
ethical evolution. Huxley still held this view. The
practice of that which is ethically best-what we caU
goodness or virtue-involves," he says, " a course of con-
duct which in all respects is opposed to that which leacte
to success in the cosmic struggle for existence. But
Darwin himself has shown that the moral faculty might
in the first instance well be due to the action of natural
selection ; for, as Romanes pointed out : " Natural selection
does not secure survival of the fittest as regards mdmduals
only, but also survival of the fittest as regards types. . . .
Success in the civil war, Where each is fightmg agamst all.
is determined by individual fitness and self-reliance. But
success in the foreign war is determined by what may be
termed tribal fitness and mutual dependence. It is
the tribes with the greatest capacity for social coherence
that have shown themselves the most successful m the

struggle for existence. , ,. ^ _

But the rule of the survival of the fittest by the exter-
mination of the unfit can hold only for prumtive society
As soon as more humane methods of warfare obtam. which
do not aim at the annihUation of the vanquished foe ; especi-
ally, however, with the spread of humanitarian ideak.
nature, "red in tooth and claw," becomes subdued by
man. her own product, who substitutes for the crude and

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258 THE FIRST PRINCIPLES OF EVOLUTION

cruel way of natural selection that of rational choice and
social amelioration. Man becomes master of his environ-
ment by his conscious purposive efforts. Not infrequently,
as D. G. Ritchie pointed out so well, the conquered people
impresses its individuality upon the conquerors, and thus
proves, after all, to be the fittest. It is more than doubtful
whether any actual improvement of mankind has taken
place in moral capacity during historical times. Man's
progress has been, on the whole, as we shall see presently,
an miprovement in the adaptation of means towards a
better and more harmonious life.

3. Evolution of Man.

We have already pointed out on various occasions that
man must be looked upon as subject to the same laws of
evolution as other animal species ; indeed, he forms but
the latest and highest offshoot of the tree of life. This
conclusion, inevitable in the light of the Darwinian theory,
soon found substantial verification. As early as 1863
Huxley showed in his essays on " Man's Place in Nature"
that man is related to the higher apes, resembling them in
all essential points ; in fact, *' the structural differences
which separate man from the gorilla and the chimpanzee
are not so great as those which separate the gorilla from
the lower apes." As regards his bodily structure and
brain organization, he must be classed together with the
anthropoid apes. We must, however, guard against the
common fallacy according to which man is descended in
the direct line from the now living man-like apes. Both
must rather be assumed to have originated from a common
ancestor of a long extinct generalized form.

The fundamental cause of man's evolution is generally
held to have been the assumption of the erect posture
at some stage of his subhuman existence (see Fig. 84).
The freeing of the upper limbs led, on the one hand, to
the acquirement of skill in the use of tools, and, on the

EVOLUTION OF MAN

259

other hand, by this very extension of man's capabilities,
to the intense development of the brain centres. It is

< ^
(fi ^

52 ^

O
H

(d
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this which differentiates man from his nearest congeners.
As A. R. Wallace pointed out, man has undergone little or

J-J"Bii.'.f . "381.1

260 THE FIRST PRINCIPLES OF EVOLUTION

no bodily change since he first entered upon his full human
inheritance ; he has been able to adapt himself to the
changing conditions of his existence by an ever-progressmg
intellect. It is the advance in brain capacity that marks
his successive evolutionary stages. We therefore find, as
we trace the gradual ascent of man from his earliest pre-
cursors, a continuous increase in the size of the skull
(see Fig. 85). At the same time, the brutish features,
indicated by the promment eye-ridges and heavy jaws

(t,b

EVOLUTION OF MAN

261

Fig. 85. — Outline of Skulls.

a Ordinary Irish skull ; h, man of Spy ; c. Neanderthal man ;
d. Pithecanthropus ; e, gorilla.

(From a paper in " Nature,^ February 26. 1895. hy DrD J Cunningham. By per-
^ f K wwstow of Messrs. MacmtUan and Co.)

with receding chin, which serve the needs of powerful
muscles, slowly disappear (compare the iUustrations m

Fig- 86). . X J • .t.

The earliest evidence of prehistoric man found m the

first half of the nineteenth century by Boucher de Perthes

and others met with no credence, as was natural in view of

the biblical prejudice in pre-Darwinian times. Slowly,

however, as the finds accumulated, and new light was shed

upon the origin of man by the evolution theory, the high

antiquity of man became an established fact. His first

appearance can with certainty be traced so far back as
the Pleistocene Age, and has by later authorities been
referred back to the Pliocene and even Miocene period.
The most primitive man-like remains yet found are those
discovered in Java (1891) by Dr. Eugene Dubois. They
consist only of a skull-cap, a thigh-bone, and two teeth,
and have become famous as affording at last the long-
sought " missing link " between ape and man. The ape-
man (Pithecanthropus erectus) of Java (see Fig. 86a) in
any case stands midway between the two types, and has
variously been assigned to the early Pleistocene or Pliocene

strata.

It is usual to divide the prehistoric age of man into
various periods, according to the character of the tools
employed by him. Thus earliest man only used imple-
ments of stone, and only very much later did he learn
the art of using metals. We thus speak of the Stone
Age and the Metal Age respectively, the latter extending
right into historical times. The Stone Age itself, which
lasted throughout the greatest part of the Quaternary
epoch, has been subdivided into Palseolithic (old stone)
and Neolithic (new stone) Ages. The existence of a still
earlier— Eolithic— Stone Age, maintamed by some authors,
has so far not been accepted on the evidence adduced.
There is doubt whether the eoliths are of human manu-
facture.

Coming now to the description of palaeolithic man, it
must be pointed out that he is known by a number of
fossil remains found in various localities, mainly in Europe,
but lately also on other continents. The most typical
example is, perhaps, the Neanderthal man, discovered in
1856 at Neanderthal (near Dusseldorf, in Germany). The
skull is, like all others of palaeolithic man, of the long-
headed type, with flat, retreating curve and beetling brow.
It was declared by Huxley to be the most ape-like known—
i.e., before the discovery of Pithecanthropus. We can re-
construct to a certam extent the life of these first men, as

262 THE FIRST PRINCIPLES OF EVOLUTION

Fig. 86. — Skull of an Orang.
{From " Mammals, Living and Extinct," by G. Flower.)

Fig. 86a. — Skull of the Fossil Ape-Man of Java {Pithecan-
thropus ereclus), restored by Eugene Dubois.

(From HaeckeTs " EvoltUion of Man.")

EVOLUTION OF MAN

263

Fig. 86b. — Skull of Negro.

Fig. 86c.— Skull of Kalmuck.
(From " Ethnohgy," by A. H. Keane.)

EVOLUTION OF MAN

265

Fig. 87.— PALiEOLiTHic Implements. (From Kent's Cavern.)
a. Flint implement ; h, bone awl ; c, harpoon head ; d, needle.

(From *• Ethnology;* by A, H. Keane.)

thev roamed over Europe and Great Britain (then stiU
connected -with the mainland), from the ample specmiens
of their work which have been collected in the numerous
places of their habitation brought to light, especudly m
England and France. It is customary to speak of two
periods of the PalaoUthic Age, according as the rehcs are
found in " river-drift "-4.e., in the deposit of bnck-earth
and gravel, forming the present terraces of river-bante-
or in caves where primitive man took shelter But this
sequence cannot strictly be maintained. The most
commonly accepted division is that proposed by M. de
MortUlet who distinguishes the Chelhan, Mousterian,
Solutrian, and Madelenian epochs,* the latter three
corresponding roughly to the Cave Age.

The earliest stone unplements (exceptmg the doubtful
eoliths) were of the most primitive kind. They consisted
mostly of chipped flints, oval or oblong, with a cutting
edee which was generally confined to the point, leavmg the
remainder for a grip. Scrapers borers, knives, spear-
heads, etc., were thus crudely fashioned. Among the
cave remains there are also to be found awls, harpoon-
heads, needles, etc., made of bone or horn (see Fig. 87).
Some of these products, especially of the Madelenian
period, show remarkable artistic decorations, representing
roughly engraved sketches of animals associated with
the cave m^ (see Fig. 88). We know from fossil remains
that the mammoth, woolly rhinoceros, hyana, and other
tropical animals, existed together with palaeolithic man m
Great Britain, France, etc. ; and we must conclude that
the cUmate at that time was much warmer m those regions
than now. On the other hand, the Arctic remdeer is also
typical of this period. Professor Boyd Dawkms argues
from this that, as the cUmate ahernated between hot and
cold there occurred seasonal migrations of the fauna from
south to north, and from north to south. Professor Keane,
* The names refer to places in France, where the most typical
implements have been f omid.

wwiiinwim'^i'iliHr"

EVOLUTION OF MAN

267

266 THE FIRST PRINCIPLES OF EVOLUTION

however, does not think such periodical migrations prob-
able, and surmises rather that the reindeer lived at those
times in temperate climates. The life of palaeolithic man was
extremely simple. He was a hunter and fisher; his
clothing consisted of animal skins. No trace of pottery,
no kind of burial, is known of that period. It is even
doubtful whether, in the earUest stages, he was able to
kindle fire. The modern Australian aborigines were, when
discovered, the nearest representatives of this low type of

culture.

The question here arises : Where did primitive man come
from? Has all mankind descended from one original

Fig. 88. — Sketch of Mammoth.
{From •' Anthropology;* by E. B. Tylor.)

stock, as the monogenists assert; or have we to posit
with the polygenists several primitive races of independent
simian origin ? We cannot here enter fully into this
dif&cult subject. The main argument of the polygenists
is based at present on the evidence of language ; for it
has been impossible to reduce the multiplicity of linguistic
groups to one common type. The answer to this is that,
generally speaking, language is no test of racial descent.
It could hardly be maintained that every stock language
presupposes a separate original race. On the other hand,
anthropological evidence points to the unity of the human
race. There exists complete fertility between the various

ethnical groups of man, thus showing that they have to
be considered as varieties of the same stock rather than dis-
tinct species. Further, as Darwin has already pointed out,
the numerous, often unimportant, resemblances between
the several races of man in bodily structure and mental
organization point to a common origin. The objection
that it is inconceivable that all the various coloured races
could have sprung from one common progenitor is met
by A. R. Wallace with the argument that man in his sub-
himian stage was most probably more plastic.

When we try to discover the birthplace of man, we are
largely led by conjecture. Seeing that man is related to
the higher apes, America as an independent centre of
evolution for man is clearly out of the question. The
plateau of Central Asia used to be the favourite locahty
for man's derivation, from whence all civilization was
supposed to spread by successive waves of migration.
But later evidence points rather to a lost Indo-Afncan
continent as the cradle of mankind. This was situated
untn Tertiary times where now the Indian Ocean lies,
covering also a great part of the scattered Australasian
islands. It is in this region that the lemurs and anthro-
poid apes are found, both of which, through their fore-
bears. He in the line of human ancestry ; and it is here,
too, that, in accordance with the theory, the transitional
ape-man of Java was discovered. It is generally con-
ceded that the immediate precursor of man was an arboreal
furry animal, described by Quatrefages as probably ' red-
haired and yellow-skinned." Yellow-brown, too, seems
to have been the primitive colour of man, aU the other
colours being derivative. Thus, e.g,. is explamed the fact
that the children of the black Austrahans and of some
negroes are of a pale brown colour when born, darkening
only in later age. The assumption of an Indo-Afncan
continent also affords the besc solution for the rather
complicated and still unsolved problem of migration of
races. From this centre dispersion was possible m all

•j-'-^

268 THE FIRST PRINCIPLES OF EVOLUTION

directions by land routes, for the Mediterranean basin
was then still dry land connecting Europe with Africa,
while America could be reached from Europe by the now
vanished North Atlantic continent. Ethnological evidence
also tends to show, according to Professor Keane, that the
first man to arrive in Europe came from North Africa,
whither he had wandered from his original seat in the
Indo- African continent.

There appears to occur a complete break between the
old and new Stone Ages, so far as Great Britain and
Western Europe are concerned ; though it is clauned by
some authorities that— at least in some regionsr-a con-
tinuity of culture can be traced, to which the name of
*' mesoUthic " has been applied. Europe was, according
to common opinion, repopulated by neohthic man, who
arrived from the east or south. He must therefore have
undergone a continuous evolution from palaeolithic times
in southern and south-eastern lands (the Mediterranean
seaboard, Arabia, India, etc.), which were not subject to
the irruption of the great Ice Age. Professor Keane holds
that the first settlers came most probably from Mauretama,
across the Straits of Gibraltar-a taU, long-headed race
(related to the ancient Iberians and Picts of Great Britain).
It was only much later that barbaric invaders arrived by
the way of the Danube, who have been identified by some
with the small-statured, short-headed Kelts.

The Neolithic Age, the beginning of which may roughly
be dated back to about a hundred thousand years ago,
is distinguished by a great improvement in the working
of the stone implements. Characteristic is the pohshmg
of tools, which consist of " celts," saws, knives, hammers,
barbed arrow-heads, etc. (see Fig. 89). Haftmg had
been learnt, the stone being perforated and supphed with
a handle. As typical remains of the earher kind of culture
must be mentioned the " kitchen middens," huge accuniu-
lations of the refuse left by the men of that age, especially
in Denmark. They show that the dog had been tamed

EVOLUTION OF MAN

269

•^

Fig. 89.— Neolithic Implements. (After Sir John Evans.)

A Polished celt and original handle (Cumberland) ',B, Perforated
hammer (Scarborough); C, barbed arrow-heads (Yorkshire

Wolds). ^^^^ ^^^^^ "Primitive Man.")

•^Hfimr^mwmmmm

270 THE FIRST PRINCIPLES OF EVOLUTION

and pottery had been invented, but the wonderful skill
of Madelenian art was entirely lost. The lake-dwellings,
found principally in Switzerland, are characteristic of the
later Neolithic period; they seem to have extended m
some places right into the Metal Age. They were built
on huge wooden piles sunk into the water. Explorations
reveal fairly advanced conditions of life. Agriculture and
cattle-rearing had akeady sprung up ; spinning, weaving,

**K ,.• . «'^ j-v"-"** (•

^W..

-^ - -vs:5f^>gsr*^^,^i;,^]t.;^^^

*».. N*'- 'Klkiww^iUlli"

Photo, Frith and Co., Retgate.

Fig. 90.— Stonehenge from North-West.

and mining were known. Burial had become customary,
as exemphfied by the widespread relics of barrows and
monumental stone (Stonehenge, etc. ; Fig. 90).

With the discovery of the metals we come nearer his-
toric times. Progress is now made very much faster.
The prehistoric Metal Age may be dated back about
twenty thousand years. It started with the use of copper,
on which followed bronze, an alloy of copper with tin.
Iron was smelted only much later, and brings us right
into the historical period, the earliest records of which

EVOLUTION OF SOCIETY

271

III

are now carried back by the latest authorities about ten
thousand years, to the beginnings of Egyptian culture.

4. Evolution of Society.

Man is a social being and lives in groups. These are not
mere agglomerations of individuals, as we find them among
lower animals, but have a definite organization, which,
slowly evolving throughout the ages, has become more and
more complex.* It is customary to distinguish three stages
in the development of human society— namely, savagery,
barbarism, and civiHzation. These ethnical periods must
be conceived as having succeeded each other, but they can
be traced to a large extent from existing types of societies,
which, having remained on a lower stage of culture, reveal
a more primitive condition of mankind.

Without going into the smaller subdivisions of each
period, we may describe the savage state as consisting in
a life dependent on the wild products of Nature. Fruits,
nuts, and fish form the staple food ; natural shelters, later
on primitive dwellings, serve as protection against the
weather. Clothing and the use of fire become known only
in the later stages of the period, while the materials used
for weapons are flint, bone, and, during the higher stages,
copper. The bow and arrow are, according to L. H.
Morgan, the most advanced inventions of savage man.

The same authority would put the art of pottery as
marking the next period — barbarism. With it we have
the advent of husbandry and stock-breeding. The making
of clothing, the building of canoes, the construction of
permanent dwellings, first of wood, then of stone, gradually
improve as we ascend towards civilization. The smelting
of iron leads to the fashioning of metal implements. Social
organization, which was very rudimentary in the savage

* The insect-communities of ants, bees, etc., are also organized ;
but, being based on a division of functional types, they are rigidly
determined by instinct.

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liRMI

(•■"WP*^

MUI M

t.li.WWii

272 THE FIRST PRINCIPLES OF EVOLUTION

period grows apace. Tribal usages and customs are
dowly codified into rudimentary laws, while political power
becomes established in hereditary chieftainship, etc. The
invention of writing and the formation of an alphabet
characterize the advent of civilization wherewith we enter
into the domain of history. .

We are unable within the limits of this work to give an
account of social evolution in all its aspects, but must con-
tent ourselves with a short survey of what may be con-
sidered the basic institutions of society. These are :
A The Family ; B. The State ; and C. Rehgion. We shall
conclude the chapter with a short r6sum6 of the position
of science and its application to the problem of social
progress.

A. The Family.
Nothing would seem more trite than the observation that
the family forms the basis of society. Yet this is by no
means self-evident. It will become apparent in the follow-
ing pages that the origination of the State is closely bound
up with the organization of the family. The study of the
family, therefore, naturally precedes that of the State.

What constitutes a family ? To the average layman the
answer is obvious: it consists of the two parents, father
and mother, and their children. Yet this modern family,
as we know it, has a long history of development behind it,
the initial stages of which are, as we shall see, not yet fully
cleared up. In the exposition of the various theories we
shall largely follow G. E. Howard's excellent r6sum6 of the
subject in his " History of Matrimonial Institutions.

(a) The Patriarchal Theory.
The earliest modern scientific investigation into the con-
stitution of the primitive family is that by Sir H. Maine,
who in his " Ancient Law " (1861) espoused the well-known
patriarchal theory. Scripture has made us famihar with
the patriarchs of the Old Testament. But the mam evi-

'■Pi'

EVOLUTION OF SOCIETY

273

dence for his views Sir H. Maine found in the Roman family
before its transformation and decay during the historical
period. The patriarchal family consisted of the eldest
male and all descendants in the male line only. " None of
the descendants of a female were included in the primitive
notion of family relationship. ' ' Strangers could be admitted
into the family by the legal fiction of adoption. All persons
thus coming under the authority of the father of the family
(paterfamilias) were said to be connected by agnation.*

The power of the house-father {patria potestas) was
supreme, extending during his whole lifetime over all mem-
bers of the household, even over married sons, their wives
and children. He had over his children " the power of life
and death, and a fortiori of uncontrolled corporal chastise-
ment " ; he could " modify their personal condition at
pleasure " ; he could " give a wife to his son " ; he could
" give his daughter in marriage " ; he could " divorce his
children of either sex"; he could "transfer them to
another family by adoption " ; he could " sell them." The
" Children under Power " could not " hold property apart
from their parent. ... The father was entitled to take
the whole of the son's acquisitions." But it should be
observed that the paterfamilias was answerable for the
deUcts (or torts) of his " Sons under Power," as he was
similarly " answerable for the torts of his slaves." The
subjection of woman was complete LegaUy she became
the daughter of her husband, and therewith subordinate

to his patria potestas.

We cannot here enter into a discussion of how such
extreme power came to be vested in the eldest male of the
family. Sir H. Maine thinks that " impHcit obedience of
rude men to their parent is a primary fact," while, " at the
same time, if it is natural in the sons to obey the father, it is
equally natural that they should look to him for supenor
strength or superior wisdom." The patriarchal system of

♦ Cognation, on the other hand, impUed the kinship in the modern
gpQse to a common pair of ancestors.

■n

274 THE FIRST PRINCIPLES OF EVOLUTION

the family can be traced among the Romans, Hindoos,
Sclavonians, and the Indo-European stoclc in general ^^
also among Semitic people ; and, remarks Sir H. Maine
•' the difficulty is rather to say what races were not
originally organized on the patriarchal model.

But though the patriarchate is generally admitted to have
formed an historical stage in the development of the family
of certain peoples, it was by no means a universal stage
Lsed through by all races ; least of aU can it be looked
upon as " the primeval condition of the human race, as

Sir H. Maine would have it. , j • * +i,„

Of the many objections brought forward against the
patriarchal theory by Spencer. McLennan, Westermarck
and others, we shall only mention the most important. In
the first instance, societies based on the patriarchal system
are mainly pastoral or agricultural, which presupposes a con-
siderable degree of culture and social organization. Also,
the idea of patria foUstas and all it involves is much too
complex a legal notion to be attributed to mankind in its
pStive be Jnnings. It would seem that Sir H. Maine, m
expounding his patriarchal theory, had too much in view
Roman society, which implied already a very advanced
tvpe of civilization. Besides this, the fundamental assump-
tion of the patriarchal theory has been traversed by
McLennan and others on the ground that descent and in-
heritance in primitive races does not follow exclusively the
paternal side. In fact, the upholders of the theory of
mother-right maintain that succession in the maternal line
is the more archaic form of the family.

(6) The Matriarchal Theory.
The idea of mother-right originated with the Swiss
scholar Johann Jacob Bachofen, and was later worked out
independently by L. H. Morgan and J. F. McLennan.
Though the details of thek schemes vary, all three assume
promiscuous intercourse as the first stage of human sexual
relationship ; this was followed by mother-right, which in

EVOLUTION OF SOCIETY

275

its turn was later replaced by father-right. Bachofen, whose
" Mutterrecht " (mother- right) appeared in 1861 — the
same year as Maine's " Ancient Law "—holds that, after
the initial phase of unregulated hetairism, gynocracy arose
through the revolt of the women against their degradmg
condition. It was women's higher rehgious attitude which
^^nabled her to influence man and rob him of his natural
physical superiority. Such gynocracy involved, not only
recognition of kinship in the maternal line, but also the
rule and leadership of woman— Amazonism. This, again,
through a change in religious feelings, made room for the
higher social relationship of fatherhood. As a rehc of the
old state we find the curious religious Aphrodisian ntes.
These must be interpreted, according to Bachofen, as an
expiation to the goddess for the curtailment of the natural
right through the exclusive appropriation of a woman by

one man. . „ , o x j- i.-

L H Morgan in his " Ancient Society (1877) distin-

guishes, after a previous stage of promiscuity, five succes-
sive phases of marriage in ascending order, which we can
merely indicate here : (i) The Consanguine Family, founded
upon intermarriage of brother and sister in a group;
(2) the Punaluan* Family, founded upon intermarriage of
several sisters (or brothers) with each other's husbands (or
wives) in a group ; the group of men being conjointly mar-
ried to the group of women ; (3) the Syndasmian or Painng
Family, where marriage takes place between single pairs^
but without exclusive cohabitation, and continues during
the pleasure of the parties ; (4) the Patriarchal Family
being the marriage of one man with several wives ; and
(c\ the Monogamian Family, based on marriage between
single pairs, with exclusive cohabitation. The scientific
evidence on which Morgan's conclusions rest— namely the
assumption that the nomenclature of the classificatory
svstem of relationship denotes actual kinship— has been
severely assailed by later criticism. This, in conjunction
♦ Named after Punalua, the Hawauan system of kinship.

276 THE FIRST PRINCIPLES OF EVOLUTION

with various other arguments brought against the existence
of communistic marriage, with which we shall deal presently,
has practically disposed of Morgan's elaborate scheme.

Perhaps the most thoroughgoing attempt at an explanation
of the matriarchal system has been made by J. F. McLennan
in his "Primitive Marriage" (1865), republished in
"Studies in Ancient History" (1876). He, too, starts
with a state of promiscuity, when " groups would hold
their women, like their other goods, in common. And the
children, while attached to the mother, would belong to
the horde." He assumes that through the practice of
infanticide of females, so common in primitive races, a
dearth of women would ensue, which would lead to habitual
wife-capture from other tribes, and therewith to the custom
of exogamy— t.^., the prohibition of marriage between
persons of the same blood. This scarcity of women
resulted in polyandry, which therefore must be looked
upon as the next stage in the evolution of marriage. As
fatherhood was uncertain, kinship was reckoned through
females only. The several husbands of the wife were at
first not necessarily related to each other. In the higher
form of polyandry, however, they are brothers—as, for
instance, in Tibet. As meanwhile the woman has passed
from her mother's house to that of her joint-husbands,
taking up her abode with them, the transition was effected
to the higher form of marriage, recognizing fatherhood.
For in the last-mentioned case " the father's blood, though
not the father," became certain ; while, with the recognition
of the elder brother as the virtual father, marriage gradually
approached the monogamous type. The obligation of the
younger brothers among certain people to marry in turn the
widow of their deceased elder brother, as also the levirate
known among the Hebrews, which enjoins a man to marry
the widow of a childless brother, and other similar customs,
are, according to this view, nothing but survivals of the once
generally existing state of the higher form of polyandry.
McLennan's theory has been vigorously attacked, espe-

EVOLUTION OF SOCIETY

277

cially by Herbert Spencer, who showed that its fundamental
assumptions are fallacious. In the first instance, the loss
of women through female infanticide is in the savage state
counterbalanced by the heavy death-rate of the male
population through warfare ; secondly, seeing that mutual
wife-stealing among adjacent tribes could not possibly
remedy the scarcity of women among all the tribes, exogamy
could scarcely become a general recognized form of mar-
riage. Furthermore, there is no regular connection between
polyandry and wife-capture ; for, on the one hand, we find
polyandry among peaceful tribes, and, on the other, wife-
stealing goes more often together with polygyny, the
captured women forming additional wives to the

conqueror.

The question arises : How far can original promiscuity
(" communal marriage," as Lubbock called it) and the
matriarchate be acknowledged to have been actual stages
in the development of marital relationship ? The mam
proof of a primitive stage of sexual communism rests,
firstly, on certain cases of group-marriage, supposed to be
in existence among certain savage races, and, secondly, on
the occurrence of some survival customs, as mentioned by
Bachofen and McLennan. As to the former, their correct
observation and interpretation has been seriously doubted •
while the latter have been explained in various other ways.
The religious orgies have been attributed to phallic worship ;
the levirate may have resulted merely from the savage
notion of the succession of property, the wife being included
among the transferable chattels ; and so on. As to the
positive arguments against promiscuity, they will appear
later during the discussion of the monogamous theory.

The idea of the matriarchate as implying an actual ruler-
ship of womanhood is now generally abandoned, though
the one-time existence of mother-right— t.^., the succession
through the female Hne— is conceded by many authorities.
For it has been found that mother-right is well compatible
with the simultaneous exhibition of male dominance, the

I '■!

iPiPPRllPpPilP

278 THE FIRST PRINCIPLES OF EVOLUTION

mother's brother taking the place of the eldest male, where
the father is not the head of the family.

It was Professor E. Westermarck who, in his " History of
Human Marriage" (1891). finally demolished the assimiption
of a primitive state of promiscuity, and raised, largely on
biological grounds, the foundations for the belief in
*' original pairing " among the human species. Following
the earlier conclusions of Darwin and Spencer, he looks upon
marriage, not as a specifically human product, but as the
latest efflorescence of sex-relationship in animal life.
Marriage, according to his definition, is nothing else than
" a more or less durable connection between male and
female, lasting beyond the mere act of propagation till
after the birth of the offspring." Marriage, seen from this
point of view, is not merely a sexual act, but exists for the
purpose of rearing the young. " It is for the benefit of the
young that male and female continue to live together.
Marriage is therefore rooted in family, rather than family in
marriage." Now, promiscuity is by no means the rule
among higher animals. Birds are notoriously monogamous
in their unions, while animals of prey and the higher apes
live generally in pairs. In tracing back, then, human mar-
riage to its earliest stage, we must assume it to have started
with a condition resembling that of man's ape-like ancestors.
Furthermore, general promiscuous intercourse would be
prevented by existing sex- jealousy of the combative males,
which, as Darwin already pointed out, holds good also for
primitive man. Finally, evidence tends to show that pro-
miscuity as a rule leads to infertility ; it could, therefore,
not possibly form for any length of time a regular custom
without leading to the extinction of the race. As Professor
L. T. Hobhouse puts it : " Sheer promiscuity is probably
to be regarded rather as the extreme of looseness in the
sexual relations than a positive institution supported by
social sanctions."

f^.

EVOLUTION OF SOCIETY

279

How have the other forms of marriage, polyandry and
polygyny, arisen in the course of evolution ? We have
already seen that McLennan's explanation of polyandry,
which ascribes its origin to the prevailing scarcity of
women, cannot stand. Nor, in view of the foregomg argu-
ments, can Spencer's idea be maintained that polyandry,
as well as polygyny, have originated by " successive Imita-
tions of promiscuity." Westermarck attributes polyandry
to a surplus of men, " due, on the one hand, to poor condi-
tions of Hfe ; on the other, to close intermarrying." At
best, polyandry occurs only comparatively rarely, and is
but a passing phase in the evolution of marriage.

Polygyny, on the contrary, flourishes mostly under con-
ditions of opulence, where men can appropriate more than
one wife. It is generaUy only the most powerful or
wealthiest who Uve in the state of polygyny. " It there-
fore presupposes," as L. H. Morgan akeady observed, a
considerable advance of society, together with the develop-
ment of superior and inferior classes." By degrees poly-
gyny tends to give way to the monogamous union, which,
by its stronger emotional bond between husband and wife,
acquires with it a great biological advantage for the
family. The transition is achieved in two ways. In the
first instance, as akeady remarked, it is generaUy only the
nobility and the rich who can afford to have more than one
wife, monogamy thus becoming compulsory through neces-
sity among the bulk of the poorer classes ; secondly, there
is the tendency for one of the women of the household to
become the chief wife, the remainder holding merely the

place of concubines.

Starting, then, with the family in the primitive state, con-
sisting of a more or less temporary union of both parents
with their offspring, we pass through the stages of polyandry
and polygyny, which at best form but collateral branches
in the development of human marriage. Mother-right
may be considered to have preceded the patriarchate, in
which the family becomes more firmly knitted together

■'^■^W'

280 THE FIRST PRINCIPLES OF EVOLUTION

through the influence and rule of the paterfamilias. At
the next higher stage we once more return in a circle, as
it were, to the original monogamous union, this time of a
highly-developed kind, with a strong permanent feeling of
responsibility on the part of the parents towards each other,
and to the children, though reUcs of the old subjection
of woman still Unger on. The highest mode of human
marriage, which shows signs of becoming the prevalent type
in the near future, is the one where " the closest moral
bond " exists between husband and wife, while at the same
time the fullest " legal and moral personality " of the
woman is vouchsafed, as well as that of the man.

B. The State.

It has been pointed out previously that, to use the words
of Herbert Spencer, " the mere gathering of individuals
into a group does not constitute them a society. A society,
in the sociological sense, is formed only when, besides juxta-
position, there is co-operation." Now, it has already been
indicated that the organization of the State is largely de-
pendent on the prevailing type of the family; while we may
add here that the forms of family organization stand in
close relationship to the economic modes of production.
Co-operation in groups, be it for the purpose of industrj'
or of warfare, has been the main lever in the attainment of
the higher stages of civiUzation. In tracing the evolution
of the State, we shall find that these groups were in the
first instance based on community of kinship, and only very
much later, in comparatively recent times, was this gradu-
ally replaced by community of local interest.

(a) Primitive Communism.

Hunting and fishing are the most primitive modes of
industry. Wandering from place to place in quest of game,
savage man constantly shifts his hunting-ground, which
for the time being is considered the prerogative of the tribe

EVOLUTION OF SOCIETY

281

frequenting it. The chase being carried on jointly by the
tribe, the spoils are divided in equal portions among the
tribesmen, with the exception, perhaps, of the chief, who
receives a preferential share. Social organization at this
stage is low as yet, as seen, for instance, in the case of the
Veddahs, who merely form a roving horde, and can hardly
be said to have formed a society.

A marked step in advance is made by the domestication
of animals. We find most pastoral people, though still no-
madic, arranged on the patriarchal system, which becomes
the upwards-tending type of society, as soon as the adoption
of agriculture leads to a settled habitat. It is this stage
of society which is generally described as primitive com-
munism, and we shall now examine it more fully in its
economical and political aspects.

The land in primitive times is held in common by the tribe
occupying it. This holds good, not only for the pastures
of nomadic races, but also for the arable land of the more
settled communities. The " village community " is the
typical form of society in the early stages of agriculture,
through which all races are supposed to have passed in
the course of their development. After G. L. von Maurer
had first described (in 1854) the old Teutonic conununal
system of the Mark, traces of primitive conununism were
discovered in nearly all civilized countries (England, France,
Switzerland, etc.) ; while in the more backward eastern
countries (Russia, India, etc.) the same system was found to
be still extant in a more or less modified form.

In the original village community the primitive tribal
organization is still maintained to the full. The land
around each settlement forming a village is divided into
three kinds — ^arable land, pasture and meadows, and the
still unreclaimed forest and waste lands. To the last all
households of the community have an undisputed common
right of use for wood, game, etc. ; while pasture-land also
is generally held in an undivided state, being kept as a
common grazing-groimd for cattle, etc. In the most primi-

EVOLUTION OF SOCIETY

283

282 THE FIRST PRINCIPLES OF EVOLUTION

live village communities the arable land, too, is the property
of the tribe, and is cultivated in common, the produce of
the harvest being distributed among the families of the
village. But more often the land is portioned out to
the separate family households, while the tillage and the
harvesting are still done jointly. Each family has only the
temporary usufruct of the allotted piece of land. This
custom leads to important consequences. As each house-
hold is deemed to have equal rights in the community
(excepting the chief of the village), the land, unequal in
quality in the various parts, is redistributed from time to
time by lot, the portions allotted to each family consisting
of small strips which lie intermingled with those of other
famihes. Custom holds primitive society in its grip as with
an iron hand. A rigid system of rules, derived from remote
antiquity, binds down each member of the community,
and determines when and how each operation in the field
is to be performed. The very fact that the strips of land
allotted to each family are not contiguous with each other,
and are too small to be tilled separately, leads to a continu-
ance of the unprogressive co-operative system of field work
long after the communistic spirit has died out in the medi-
eval village. The redivision of land originally takes place
yearly, but may be deferred for a number of years, until
finally the redistribution is dropped altogether, and the
individual shares remain permanently in the possession of
each respective family. Village communities can be found
in all these stages of transition. It must be distinctly
pointed out that the land does not become the property of
any given individual, but belongs to the family as a whole.
The patriarchal family is a unit, and has not yet broken
up. as happens in later times. At the stage just mentioned,
the old communal rights are still traceable in the fact
that the land is inalienable, and cannot be disposed of with-
out the consent of the village council ; while, as we have
seen, the tillage is still managed jointly by the combined
households.

Coming now to the political organization of the village
community, we have already remarked that it is arranged
on the patriarchal system. In fact, the village is nothing
but the patriarchal family " swelled into the clan." All
members of the village conununity have, or at least claim
in theory , descent from a common ancestor. Strangers may
be admitted into this self-contained society by adoption,
which makes them legally kin to the tribesmen. All mem-
bers of the archaic communistic State are essentially free-
men with equal rights, all matters pertaining to the com-
munity being decided in council, which is presided over by
the eldest headman, who but administers the affairs of the
village according to old-established usage. Law, too, in
the primitive state is not a matter of equity between persons,
but consists merely in the right of retaliation between
families. A murder committed is not so much a crime
against the life of an individual, but rather a loss to the
family, which has to be avenged by taking the life of a
member of the slayer's family, if the murderer himself cannot
be killed in revenge. The earlier stages of human civiliza-
tion are dominated by the blood-feud, which is somewhat
mitigated in later times by substituting for it payment of
compensation (wergild), graduated according to the com-
puted value of the tribal member.

For we find that in time gradations of rank establish them-
selves among the originally free and equal tribesmen. The
eldest of the clan at first only acts as headman of the
council. He may, however, become elective and assume
real rulership, be it through his valour in war, which secures
him permanent military chieftainship over his followers, or
through his greater amount of wealth, acquired partly from
war booty, partly from his special share of land, which
enables him to keep more cattle and sheep. The constant
raids also lead to the subjection of tribes, and therewith to
the institution of slavery, which is a conspicuous feature
of all stages of civilization up to very recent times. The
tribal stage of society is exemplified as much in the City

284 THE FIRST PRINCIPLES OF EVOLUTION

States of ancient Greece and Rome as in the agricultural
village communities of the Teutons. Fustel de Coulanges
has shown admirably how the religious family cult of the
patriarchal system pervades the whole life of the Ancient
City.

Before tracing the further development of the tribal
state into the next stage— that of feudalism— we must not
omit to point out that the existence of a primitive com-
munistic society is by no means accepted by all authorities.
One of the foremost critics is Fustel de Coulanges, who, after
sifting all the given evidence in favour of primitive com-
munism, holds it to be of insufficient proof. Without alto-
gether denying the one-time existence of such a state of
society, he maintains that the documents adduced have
been misinterpreted ; that the land has always been held
subject to overlordship. All that can be asserted is family
ownership of land, which is not equivalent to communal
ownership. On the other hand, his opponents believe that,
apart from philological interpretation of documents, there
are positive facts of a number of survivals which can only
be explained on the assumption of a primitive tribal com-
munism, which is nowadays the generally accepted theory.

(b) Feudalism,

The village community represents, as we have seen, the
tribal stage of society. Agglomerations of such tribal com-
munities, with a powerful leader as king at their head,
have been formed over and over again in history, but proved
mostly of temporary character only, and left no permanent
effect on the general progress of society. It is by the
gradual fusion of a number of tribes into one organic whole
that the state, in the real sense of the word, came into being.
Feudalism proved to be the necessary transition stage from
the patriarchal society, based upon kinship, to the modern
society, based upon citizenship. The Roman Empire,
though master over nearly the whole of the then known
world, failed to consolidate its vast possessions, because it

/ '

EVOLUTION OF SOCIETY

285

remained essentially a City State, centralized in its govern-
ment, which, incapable of expansion, remained foreign to
the greater part of its subjects.

Feudalism arose as the result of the barbarian invasion
of the Teutons into the Roman Empire, and can be said to
have originated in the ninth century after Christ with the
Franks. The ancient Teutonic communities were organized
on the tribal system. But the constant warfaring expedi-
tions and the occupation of newly conquered territory by
the German tribes led to a series of consequences which
ultimately changed a community, based on freedom and
equality, into a society of vassalage and serfdom. The actual
stages of transition are still subject to a great deal of sur-
mise. But various points stand out sufficiently to indicate
the process of feudalization. In the first instance, the
chronic state of war gave the warrior chiefs greater and
greater prominence, and made them ultimately powerful
lords, with a strong following of devoted men who lived
in a sort of dependence from them, giving their free
service in return for a share in the booty. On the other
hand, we have already seen that the village chief often
became the ruler of the community by acquiring great
wealth and influence. It is from these two sources that
the feudal barons of the Middle Ages were derived. They
gradually accumulated into their hands large domains of
land, which originally belonged to free conununities. This
happened in several ways. There is first of all the custom
of " benefice," by which the king bestowed parts of newly
conquered territory upon the chieftains in return for certain
services and duties. The benefice was originally given
merely for a number of years, but was gradually extended to
last for the whole lifetime of the vassal, and finally became
hereditary, just as the rulership of the villages, at first given
to certain prominent families by mere custom, was ulti-
mately claimed by them as an hereditary right.

But the " lord of the manor," as he was called, managed
in time to appropriate to himself also a great deal of com-

iwmi, .JV.''*i''

'WW-ill !■<* ■ >

286 THE FIRST PRINCIPLES OF EVOLUTION

munal land of his own tribesmen. The free owner of the
land often found it useful in those troublesome, lawless
times to put himself under the protection of a superior lord,
able to defend him. In return for this protection he volun-
tarily yielded his land to the lord, henceforth to hold it
from the lord as a benefice. Thus were many freemen
turned into dependent tenants. The waste lands and
forests were frequently made over to the lord by royal
grant, and their use by the villagers became subject to the
lord's " right of approvement." Often, however the tillage
land itself was added to the lord's " demesne," bemg either
seized by sheer force or wrested from the impoverished
freeman, who thus sank to the state of villeinage. The
free inhabitants of the village were thus gradually reduced
to serfdom or partial serfdom, being tied to the land which
they held in dependence from some lord, and doing compul-
sory service for him. The lord, on the other hand, it must
be said, was bound to give them protection for their loyalty

Indeed, the whole system of feudalism rested on a code
of allegiance between classes of superior and mferior status,
arranged in a minutely adjusted scale from kmg down-
ward to serf. Recognition of land tenure and service had
taken the place of the mutual bond of kmship. The same
change is apparent in the advance of justice. We have
seen that in the tribal stage the responsibility was collecti^^^^
being shared by the whole of the clan. But blood-feuds
^adually tended to become mitigated by the appeal to
Mediation before a council of elders This niethod caine
more and more in vogue during feudal times, and led to the
custom of the " ordeal by judicial combat/ which was only
" a mode of reducing to orderly fashion the old right of
personal redress." A further step was taken when the
supporters appeared merely in order to make oath on behalf
of the party concerned-a method which was called com-
purgation.- With the growth of the eudal power of the
lords a new principle arose which slowly replaced the old

EVOLUTION OF SOCIETY

287

system of family feud. The baron, the prince, the king, came
to claim the right of preserving order within the borders
of his territory. Wherever the king happened to be, the
" king's peace " was declared, a fine being inflicted for
breach of it. As the power of the king extended more and
more, the control of the king's peace spread, and finally
became general. The king now delegated his power to
certain functionaries, and this ultimately led to the estab-
lishment of judicial courts in the land for maintaining
public order and justice.

The feudal system led to very important consequences.
It carried within itself the germs of the future development
of the modern democratic state. This, as is well known,
is based upon the principle of citizenship. Every adult
member of society is recognized— at least, in theory— as a
free and responsible agent, who has aright to the full develop-
ment of his personality without let or hindrance, except
that he must not encroach upon the right of his fellow-
citizens to the same enjoyment. The bondage of the feudal
system has been broken down, serfdom been abolished. The
state is now no longer controlled by a despotic force from
above, but by the people themselves, who claim a proper
share in the government through chosen representatives.

In order to trace the change of the old hierarchical land
system of feudalism to the modern industrial state, with its
principle of free competition, we should have to follow the
rise and development of trade and industry throughout the
last five centuries, especially in England. But this is more
a subject for the economist than for the evolutionist.
Suffice it here to say that it was brought about, firstly, by
the liberation of the agricultural labouring class from the
soil, whereby they became free wage-earners ; secondly,
by the expansion of commerce and the establishment of
industrial centres, which gradually supplanted the agricul-
tural labourer by the industrial worker. The final step was
taken when, through the introduction of machinery and
the steam-engine, the small home industry was converted

\.i

mmm

m i.

288 THE FIRST PRINCIPLES OF EVOLUTION

into our huge factory system, with its international connec-
tions all over the world.

The result has been by no means unequivocally good,
especially for the wage-earning class ; for an oppressive
plutocracy has taken the place of an overbearing landed
aristocracy. Indeed, the latest phase discernible is a
tendency towards a return of collective responsibility, this
time imdertaken by the state as a whole. The individual,
detached in complete freedom from his ancient trammels,
is seen to be unable to withstand singly the intensity of the
modern competitive system, which reduces the majority
of the people to the position of cogs in the wheel of our
gigantic capitalistic machine, thus rendering their liberty a
mere sham. Signs are not wanting which indicate that the
state is going to step in more and more to render impossible
the exploitation of one individual by another, for it is
becoming recognized that each member of society is a
valuable asset to the community, and that only with mutual
hearty co-operation can the best and highest development
of each be realized by all.

C. Religion.

Society has, not unaptly, been likened to an organism.
If we look upon the family and the state as forming the
structural groundwork of the body politic, we may, whilst
guarding against too close an application of the analogy,
regard the ideological manifestations of society as the
spiritual counterpart of the social organism. In order,
then, to complete our survey of the evolution of society,
we shall deal with the development of religion, appending
a short r&imi^ of the scientific tendencies of modem times.

That reHgion must be included under the all-embracing
law of evolution is now generally admitted. Whatever
definition may be given of religion, it is recognized that
the religious consciousness, being of the psychological

EVOLUTION OF SOCIETY

289

order, has developed from a lower to a ^^g^^^.^^^^^, J^^^
among those who believe in a special revelation, there are
many who affirm that - revelation and mspiration are
pro Jessive," the Deity manifesting himself m the pnmitiv^
savage in a crude and imperfect manner, and gradually
rising to the spiritual conception in modem man.

R is customary since Professor E. B. Tylors epoch-
making work on ""^Primitive Culture '; (xSyx) to distinguish
two large periods in the evolution of religion. The tot
which Tylor denoted as the stage of Animism, impbes
The beM in spirits, which in the second stage gradudty
chanee into deities, the idea of one supreme Deity bemg
aSd as the latest outcome of this evolutionary process^

We shall first deal with the theory of Animism and then
with various other theories, critical and constmctive.

(a) Animism,
Animism is the belief in ^Pftual ^eings which are held
to control the material world, includmg man. How did
the savage mind arrive at the idea of immaterial, super-
natur J SeSs ? There is, according to this theory, as
natural agencieb • _,;„ ^ natural tendency m

'""^ r^marto'Sribno S' oljects^' a life and'wiU
Kertohs own" But this mui. as Herbert Spencer
Sted out no? be meant to imply that savage man cou^d
Etscriminate between animate and nanimate ob e^J
L this is a facuhy present already m the higher animals.

pf the living being. ^^

290 THE FIRST PRINCIPLES OF EVOLUTION

But how does primitive man arrive at this notion of a
double or ghost of his own self ? The daily experiences
of death, dreams, and abnormal mental conditions, such as
trance, ecstasy, etc., supply the necessary material. To
the savage the distinction between death and Hfe, dream
and reality, is by no means easy. Sleep, which stretches
the strong body motionless, is often accompanied by vivid
dreams, during which the sleeper himself appears to play
an active part. The explanation given by the savage is
that a ghost of his own self exists which leaves the body
during sleep to seek its own adventures, only to return on
his awaking. Swooning is a more or less temporary depar-
ture of the ghost ; while death ensues, if for some reason or
other the ghost has left the body for ever. As the savage
is by no means certain when this has occurred, he resorts
to all sorts of strange ceremonies, which have the purpose
of either delaying the departure of the ghost or of inducing
its early return. Exorcism and sorcery are the savage's
means of gaining power over the living person or over his
ghost. At first this ghost is conceived as entirely material,
separable from the body, yet dependent upon it. This fact,
which seems so unthinkable and contradictory to modem
minds, appears by no means so to primitive man. Indeed,
it belongs to the essence of the origin of the belief in the
supernatural that soul and body are in their beginnings not
conceived as entirely separate and discrete entities. This
happens later. The soul-image of the body becomes more
and more dematerialized. Assuming gradually a position
between substantiality and insubstantiality, held to be a
sort of vaporous, ethereal materiality, it is finally Hkened
to the shadow or breath, whence the etymology of the
word " spirit," which in most languages denotes " breath."
The ghosts of the departed are, in the first instance,
treated like living beings ; food is deposited at the burial-
place, arms are placed ready for them, even servants and
wives are often despatched into the next world in order
to attend upon their master in the new abode. It is from

EVOLUTION OF SOCIETY

291

these food-offerings and rituals at the grave-side that
Spencer derived all later rehgious observances. ReHgious
worship, according to him, originated with the propitiation
of ancestral ghosts ; religious sacrifice being developed
from the food-offerings, while the grave formed the germ
of the altar and sacred buildings, which were constructed
at the original haunt of the ancestral spirit.* For as the
ancestral spirit became a power far beyond the calculation
of mortal beings, it became imperative " to secure its
good-will " and " to mitigate its anger."

Once the idea of spiritual beings, modelled on the human
prototype, was formed, the analogy was easily extended
to other natural objects. Indeed, the division between
man and the animal world, or even plants, is by no means
distinct for the savage. If man has a double, why should
not a beast or a tree ? The idea that animals can take on
human shape, or that hiunan spirits assume animal guise,
has nothing strange for primitive races. Even inorganic
objects, as flowing water, the fleeting clouds, or the great
celestial bodies, become the seat of indwelling spirits, which
are their prime movers. In short, " savage theory of the
universe refers its phenomena in general to the wilful action
of pervading personal spirits."

There is a gradual transition from the conception of man-
like spirits to that of the deities of the polytheistic reUgions.
In the first place, to use the words of Professor L. T. Hob-
house : *' The spirit which dwells in an object, but which
can leave it and enter another, may clearly pass by easy
transitions into a spirit which does not necessarily dwell
in any object at all, but haunts it, or even, ceasing to
haunt it, retains control over it." Furthermore, the spirit
of a particular animal or a particular tree tends to become
the representative of the whole species of that animal or
of the whole forest. In other words, a step is made from
individual ideas to general or specific ideas. Now, as

♦ Thus the altar in the Catholic churches still enshrines the reUcs
of a saint.

292 THE FIRST PRINCIPLES OF EVOLUTION

Tylor pointed out, such generalization, expressing what
we call a " species," is accounted for by the savage by
referring it " to a common ancestral stock, or to an ongina^
archetype, or to a species-deity," or to a combmat.on o
these inceptions. Thus the idea of the supematur^
arose by separating as a divine entity what w^ ""l'^ the
merely the ghost or the soul-image of the body. To the
Ancients the world was peopled with hosts of gods, the
pantheons of Rome and Greece being the best-known

historical examples. !„:„„„

Tracing, finally, the latest step in the evolution of religious
thought, we observe a progress from polytheism the belief
in many gods, to monotheism, the belief in on-^^e only-
God, " the creator and sustainer of all that is. inis
phase may be reached in various ways. There is, first ot
all, the tendency to picture the heavenly hierarchy on the
model of the earthly kingdom, anVi to assign the position
of overlord to one of the gods, who thus becomes supreme
" the lesser deities being degraded to some lower plane ot
being." Another mode of development is through the
exclusive worship of one national god, as that of Yahveh
of early Judaism. The tribal god becomes recognized not
as the only god, but as the only god to be worshipped by
the tribe, the foreign gods of other tribes bemg despised as
idok. This stage could be denoted by the term Heno-
theism," coined by Professor Max MiiUer, and meaning the
belief in a single god. There is, finally, a third way by
which the idea of a Supreme Godhead may be reached,
namely, by the identification of many gods, fusing their
various qualities into one comprehensive whole as an under-
lying principle of the universe. This philosophic tendency,
leadmg to a search for a First or Ultimate Cause, m conjunc-
tion with the previously-mentioned fact of the exclusive
worship of a national Godhead, finally brings about the
highly abstract and sublime conception of an omniscient,
omnipotent, and benevolent Being, which is now the
generally accepted belief among all civiUzed races.

EVOLUTION OF SOCIETY

(b) Other Theories.

293

Herbert Spencer, starting from the hypothesis of a universal
animistic conception of nature, held that " ancestor-worship
is the root of every religion." But this conclusion, though
of considerable vogue, has not found general acceptance.
Anunism in itself is simply the behef that " all things
which affect man possess Hfe," but in this statement there
is not necessarily included, as Professor F. B. Jevons has
pointed out, a belief in the supernatural, though " the two
beliefs seem to have been universally combined in varying
degrees/' Animism is merely a natural explanation by
the primitive mind of the everyday experiences of life,
while the idea of the supernatural suggests itself by an un-
explainable breach in the uniform routine of nature. " It
was," says Professor Jevons, " the violation of these "
(natural) " sequences and the frustration of his " (the
savage's) " expectations by which the behef in super-
natural power was not created, but was first called forth."*
Given, then, the feeling for the supernatural— which thus
it is seen, is not explained, but taken for granted—Jevons
further traverses the ghost-theory by maintaining that
not fear of the dead, but natural affection, is the basis of
spiritual relationship; and he finds the source of this
friendly bond between man and his god in the tribal custom
of totemism. Following Professor Robertson Smith, Pro-
fessor Jevons would refer back all reUgious custom to a
primitive stage of totemism. The totem, which represents

♦ Professor J. G. Frazer holds that magic, whereby savage man
tries to work upon another person , implies a natural, though misunder-
stood sequence of events. It is merely primitive science, and, as
such, antecedent to reUgion, which he defines as " propitiation of
powers superior to man." The failure of magic, according to this
view, leads to the appeal to supernatural forces— i.e., to reUgion.
Professor Jevons. however, sees in magic merely an aberration of
the reUgious movement ; for while magic art has only to do with
malign influences. reUgion. according to him. embodies essentiaUy
a principle of love. See further.

I q

I ;

294 THE FIRST PRINCIPLES OF EVOLUTION

the tribal god in animal shape, is considered to be the super-
natural kinsman of the tribe, standing in the position of a
friendly blood-relation . Sacrificial observances are nothing
but the development of certain communion-rites with the
totem-god, based on the blood-communion between
members of the tribe. Ancestor-worship is, according to
this theory, a private and not a public cult, running a course
of its own, and becoming ultimately " assimilated in form,
in its rites and ceremonies, to the public worship of the
gods." Polytheism and monotheism are two coeval
offshoots of totemistic religion ; the former resulting from
an aggregation of different totem-gods through pohtical
union of the tribes; the latter being in reality a higher
form of the original inchoate tribal monotheism.* It
follows from this theory that " the religious element is no
part of animism pure and simple " ; there must be added
" a specifically religious idea, one which is apprehended
directly or intuitively by the religious consciousness."

A similar attitude with regard to the theory of ancestor-
worship has been taken up by Andrew Lang, though on
other grounds. He held that there are two distinct strata
of religious thought, a higher and a lower, which have no
intrinsic connection with each other. The remarkable
point is that he considered, upon the special anthropo-
logical evidence reviewed by him, the higher phase to be the
older one, which was only later pervaded and perverted
by ghost-worship. While the latter is essentially a pro-
pitiatory cult, the original religion of primitive folk, ac-
cording to this view, is a sort of monotheism, embodying
a belief in a Supreme Being. This Supreme Being is non-
dying, the creator of all things and the embodiment of
" righteousness " (of course according to the standard of
the savage) . No worship or sacrifice is connected with his
cult. Andrew Lang could not offer any explanation for
the development among savages of such a highly abstract

♦ It would perhaps be clearer to denote this early stage of tribal
monotheism as henotheism, in Professor Miiller's sense.

EVOLUTION OF SOCIETY

295

conception of an eternal creator ; but he repudiated strongly,
the attempts which have been made to account for the facts
by assuming the influence of contact with higher religious

A more abstract origin of the religious feelings has been
suggested by Professor Max Mttller. He defined rehgion
shortly as " the perception of the infinite."* and maintained
that this feeling for the infinite furnishes in essence the
element of religious experience even in its low^t and
simplest form. The primitive mind, impressed with the
greatness and vastness of natural phenomena, elevates
particular finite objects, as trees, rivers, clouds, the sky.
sun, stars, etc., into deities, thereby e''P'«s^>?g JJ^^
underlying " infinite complement." It is a sort of natural
revelation." Of course there took place a gradual develop-
ment of the religious content. Professor MiiUer, who was
first and foremost an etymologist, found the origin of the
evolutionary process in language. It is language which
first gave rise to the naming of the deity, the name being
given in the first instance from the most directly sense-
appealing characteristic. Thus the sky was caUed <te|a
(Sanscrit for " shining." " bright ") from its bnght appear-
ance. Gradually, through mythological ax:cretion other
characteristics were added as attributes of the god, sug-
eested by his name. He became a breathing and Imng
Lent (animistic stage) ; then he grew into a man-hke
being, finally to become superhuman and supematural-
a dmia or eod. Indeed, deva-or deus m Latm. Zeus m
Greek-is still the name for God. What we must clearly
understand is that " the supernatural element was there
from the beginning, though not yet disentangled from its

natural surroundings." . . x. • ii,^„„.

Two criticisms have been directed against this theory.
Firstly, it assumes as the basis of primitive religion a meta-
pSSl conception of the universe, which so far has been

» But he added later : " Under such manifestations as are able to
influence the moral character of man."

296 THE FIRST PRINCIPLES OF EVOLUTION

found only as the outcome of more advanced culture.
Secondly, the evolutionary phases of Professor Miiller's
scheme depend too much upon etymological analogies,
which to a large extent have been given up since his day

as untenable. ....

There only remains to mention the rather ongmal view
of Mr. E. Crawley. With him " religion is not a distinct
department of thought and action," but rather an " ele-
mental part of hfe,'' a " tone or spirit," which pervades all
elemental interests of life, such as birth, marriage, death,
etc. " The vital instinct, the feeling of life, the will to hfe,
the instinct to preserve it, is the source of, or rather is
identical with, the rehgious impulse, and is the origin of
religion." " Sacredness is the result of the rehgious
impulse ; the feeling of life is the cause." The animistic
view is that "it is the soul which gives life " ; whereas
Crawley puts it : " the life is the soul."

Whilst we may not go quite so far as to identify with
Mr. Crawley the religious impulse with the vital instinct
as a whole, it must be conceded that there is a good deal
of truth in his statement. The religious consciousness
has generally been attributed to a special instinct. But,
as Professor W. McDougall has shown in his " Social
Psychology," it must not be supposed that " this assumed
religious instinct of man is one that is his pecuhar endow-
ment and has no relation to the instincts of the animals."
For, " if we accept the doctrine of the evolution of man
from animal forms, we are compelled to seek the origin
of religious emotions and impulses in instincts that are
not specifically religious." According to him, " rehgious
emotion is not a simple and specific variety ; it is rather a
very complex and diversified product of the co-operation
of several instincts. ' ' We cannot here enter into a detailed
account of his excellent analysis, but may point out that
he looks upon awe (a compound of admiration and fear)
as the principal element of the religious feelings, while
reverence is awe combined with tender emotion. This

EVOLUTION OF SOCIETY

297

feehng of wonder and awe in conjunction with the natural
tendency of primitive man to interpret the processes of
nature on the analogy of his own volitional acts (animism)
must be looked upon as the main source of all religious
practice.

APPENDIX

A Precis of Science

Our account of social evolution would not be complete
without at least touching upon the important subject of
science. Mr. Crawley, identifying the religious impulse
with life itself, naturally lays great stress upon the per-
manency of the religious element of life. In discussing
the relation of rehgion to science, he is confident that
science, whilst doing useful work by the side of rehgion,
will never entirely supersede it. Ndw it goes without
saying that the rise and development of the scientific
spirit has been one of the greatest factors of human pro-
gress. Nor can there be any doubt that the method of
scientific inquiry is invading one by one the fields of human
experience formerly held to be the prerogative of religion.
We may not agree with Herbert Spencer, who defined a
rehgious creed as a " theory of original causation," but we
must admit that all religious creeds contain a good deal
of such theory. Savage man, unable to comprehend the
elemental factors underlying natural phenomena, embodies
his primitive ideas about the universe in the form of
mythological stories, which have become part and parcel
of the various rehgious systems. It is only with infinite
pains and not without a prolonged struggle against
authority, that science has succeeded in freeing humanity
from the consequences of its own outgrown behefs. In
fact, the very subject of this book — the theory of evolution
— has brought within the precincts of the " Knowable "
many facts hitherto deemed beyond the ken of the human

298 THE FIRST PRINCIPLES OF EVOLUTION

mind. It certainly has shown that man, in mind as weU as
in body, is as much subject to natural laws as the earth,
the sun, and the stars, which were formerly held to be
moved by " presiding spirits." Nay. even religion itself
has not escaped the influence of the evolutionary idea, and
is now generally treated from the scientific point of view.

There remains the final question : Is science hkely in
time to replace rehgion altogether ? The answer depends,
firstly, on what we understand by the term religion,
and secondly, on whether we beUeve the universe to be
reducible to an entirely rational system. As to the former
point, taking religion to be a natural instinct of man it
may be taken for granted with Mr. Crawley that neither
the God-idea nor the belief in ' supernatural or spmtual
is essential to religion." It foUows that the religious senti-
ment may find complete satisfaction withm the limits of
naturalism. With regard to the rationalists' attempts to
explain the cosmos by mere reason without residue there
is nowadays a considerable tendency to admit failure in
this respect. The exuberant expectations of scientists of
the last generation have not been fulfilled. But, after a 1,
it is being more and more recognized that science is only
explaining the "how" and not the "why" of natural
sequences. There is a growing feeling that after the most
exhaustive ratiocination there still remains hfe itself
" Being, the alogical," as Belfort Bax has called it, which
can never be completely reduced to rationality. Professor
H Bergson has advanced a most enticing thesis, trying to
show that, while we are excluded by the very nature of our
intellect from the elemental core of Ufe, a sort of supra-
intellectual intuition " may give us glimpses of it.

D. Evolution and Progress.

We have traversed the whole field of super-organic evo-
lution, and have foUowed the various convergent lines of
social development which have led to the existmg conditions

EVOLUTION OF SOCIETY

299

of modern civilized society. Can we draw any practical
conclusions as to the present-day problem of social pro-
gress ? The evolution theory, and especially Darwin's
hypothesis of Natural Selection, has left a deep mark upon
the social philosophy of our age. Biological ideas have
become the common stock-in-trade of the social reformer,
and are freely applied to the solution of sociological ques-
tions.

We have at the outset to guard against a frequent error,
arising from too hasty a generalization with regard to the
relationship between evolution and social progress. As
has been pointed out once before, we must be careful to
discriminate between evolution, which is a biological con-
cept, and progress, to which we must attach a social value,
implying " the realization of ethical ends." Progress is
by no means identical with evolution, which, as we have
seen, may be, and in fact often has been, retrogressive as
weU as progressive.* As Professor L. T. Hobhouse puts
it : " The fact that a thing is evolving is no proof that it is
good ; the fact that society has evolved is no proof that it has

progressed."

It is our first task to examine how far biological concepts
have real validity for the affairs of human society. In the
early triumphant days of the transmutation theory it was
too easily assumed that it would give us the key to the
problem of social progress. Natural selection became the
watchword of the writer on social questions. It was used —
by Haeckel, for instance— to justify our present competitive
industrialism as being a system allowing free play to the
" natural law " of the struggle for existence. The political
school of laissez-faire, with Herbert Spencer as its greatest
champion, saw in the biological law of the survival of the
fittest a verification of its own social theory that everything
should be left to individual initiative and individual enter-

♦ It must be noted, however, that the word " progress '* was used
by Herbert Spencer in his early essays in the sense of " evolution."
and was only later replaced by him by the latter term.

■M

„„,g,giiig

300 THE FIRST PRINCIPLES OF EVOLUTION

prise, trusting that the best would ultimately come out at
the top in this peaceful warfare. It is only of late that
these crude applications of biological theory to sociological
facts have been discountenanced by more thoughtful
inquiry into the whole subject of human progress.

Darwin already recognized the fact that " the moral qual-
ities are advanced, either directly or indirectly, much more
through the effects of habit, the reasoning powers, instruc-
tion, religion, etc., than through natural selection ; though to
this latter agency may be safely attributed the social
instincts which afforded the basis for the development of
the moral sense." In fact, as has been fully shown before,
the social, essentially human features of hfe have been
developed by mutual helpfulness and forbearance rather
than by internecine warfare among the members of the tribe.
Natural selection is to this extent mitigated in human
society ; or, rather, it is lifted upon a higher plane of action.
Furthermore man, being endowed with reason and fore-
sight, is largely able to adjust and modify his physical
surroundings to his own needs according to his own ideals—
that is, he is able to create his own social environment. In
other words, man, though subject as an animal to biological
laws, " is not merely an animal. He is also a rational
being, and accordingly he reacts to new circumstances in a
way that can only be determined by taking the possibihty
of rational purpose into account."

There is another fact to be considered. Natural selec-
tion, as applying to animal species, is a law of exter-
mination, the unfit being wiped out of existence. It is
otherwise among human beings. Here, especially in the
higher stages of civihzation, selection takes place without
elimination. To the physical struggle for existence there
is superadded a " ' natural selection ' of ideas, customs,
institutions, irrespectively of the natural selection of indi-
viduals and of races." This leads, as D. G. Ritchie pointed
out, to important consequences. A race may prove in-
ferior in warfare, yet may turn out to be superior by im-

EVOLUTION OF SOCIETY

301

pressing its own civilization upon the conquerors. Further,
ideas and institutions may long persist, though the race
among which they originated may bodily have disappeared.
It is social inheritance which thus plays a predominant
part in the progressive evolution of society, though actual
physical inheritance of traits can, according to the latest
views, by no means be neglected. While the racial type
varies but slowly, " it is," as Professor Hobhouse remarks,
" in the department of knowledge and industry that ad-
vance is most rapid and certain, and the reason is perfectly
clear. It is on this side each generation can build on the
work of its predecessors." Social tradition, which plays
but an insignificant role among lower animals, must thus
be considered the most powerful factor in the progressive
evolution of human society.

We are now in a position to consider shortly the practical
bearings of the foregoing conclusions. Dr. Archdall Reid
has shown that there exists a selective process in man
which still takes place in reference to the action of certain
microbes and bodily poisons. Thus it is well known that
some races are more subject to certain infectious diseases
than others. Dr. Reid would ascribe this to the fact that
in a community exposed to the contagion of a given
microbe, the least resistant members are persistently
weeded out through succumbing to the disease ; so that
ultimately a race is evolved, practically immune against
the ravages of that disease. Similarly in a race addicted
to alcoholism, those with the greatest craving for drink
succumb quickest, bringing about generation by generation
a natural " evolution against alcohol in the direction of an
increased power of avoiding it." Now it has been main-
tained that in the same manner disease and intemperance
act as a means of natural selection in our society, purging
it from its weakest and worst members. As the progress
of civilization tends more and more to check by its philan-
thropic and public efforts this elimination of the unfit, we
are, it is said, interfering to that extent with the natural

302 THE FIRST PRINCIPLES OF EVOLUTION

law of the survival of the fittest, with the result that the
race is steadily deteriorating. ^

Now, though there is an element of truth in this con-
tention, it is not quite so ominous in its significance as would
appear on the surface. We may agree that m modern
society, with its humanitarian tendencies and general
advance m hygiene, more and more chance is given to the
weak members of the community ; but which of these m
the struggle for existence shaU survive and leave progeny
is largely a matter of economic conditions. Those suc-
cumbing to disease are often merely " selected " by poverty ;
and it is far from being proved that these form the physically
unfit by inheritance.* Besides this there exists a special
liability to certain microbic diseases, such as scarlet fever,
typhoid, tuberculosis (consumption), etc., which liability
varies in different people and with regard to each given
disease. A person may be perfectly fit in every other
respect, yet fall a victim to specific germs. There is only
one conclusion we can arrive at : it is incumbent upon us
rather to weed out the bacillus of tuberculosis (which is
possible) than the tubercular patient (which, though pos-
sible, is cruel), f , ..

By many it has been argued that our modern competi-
tive system, exemplifying, as it does, the law of natural
selection, is the best method of securing the survival of the
fittest. This is true in the sense that, under any given
conditions, those " best fitted to cope with their circum-
stances " survive ; but then this statement becomes a mere
truism. The important question is : Who are the fittest ?
They naturally vary according to the selective conditions,
and may be either good, bad, or indifferent with regard to
any quality selected. Now while under our present

♦ See the author's essay. "The Discovery of the Fittest." West-
minster Review, J aniMSLvy, 1911. , • u •««

t In present circumstances, the scourge of tuberculosis being
still unabated, it is. to say the least, advisable for consumptive
people not to propagate their own kind. More on this subject in
the author's " The First Principles of Heredity."

EVOLUTION OF SOCIETY

303

capitalistic system the successful may be the " self-reliant,"
the energetic and " cute " man of affairs, he is at the same
time often the pushing, the unscrupulous, ready to oust
and crush the gentle, the dreamy, the intensely moral man
of thought and feeling. To ensure that the fittest selected
be the truly select, the socially fit, we must devise a social
system where these humaner traits may have full play
without hindrance ; where mutual co-operation becomes
the rule instead of the exception ; where, in fact, we all
may Hve up to the great ethical standard of " each for all

and aU for each."

There remains the problem of the truly unfit— those who
under no circumstances, however favourable, can adapt
themselves to conditions of social life. So long as there
existed a general belief in the inheritance of acquired
characters, no such problem arose, for it was taken for
granted that all racial unfitness could be eliminated by a
proper method of education and moral teaching. But this
idea has now largely been abandoned as contrary to the
general trend of biological science. Says Karl Pearson :
*' No degenerate and feeble stock wiU ever be converted
into healthy and sound stock by the accumulated effects
of education, good laws, and sanitary surroundings. Such
means may render the individual members of the stock
passable if not strong members of society ; but the same
process will have to be gone through again and agam with
their offspring and this in ever-widening circles, if the stock,
owing to the conditions in which society has placed it, is
able to increase in numbers." To this class of the socially
unfit belong the imbecile, the mentaUy and morally insane—
among the latter certain types of criminals, drunkards,
and vagrants, who are innately incapable of fittmg them-
selves mto any type of ordered society. Now it goes with-
out saying that the advance of humanitarian sentiment has
more and more restricted the law of natural selection from
taking effect in these cases. We provide for the degene-
rate, whUe we may punish him, and take no heed that his off-

)

W|IH])I I I|. J III 11.11

'T '■""

WM|>-' "***"' ■'! '-"«'

304 THE FIRST PRINCIPLES OF EVOLUTION

spring fill the world with an army of equally unsocial types.
Whilst favourable environmental conditions, material and
spiritual, are essential in order that growth may not be m-
hibited by inappropriate surroundings, they can only develop
the individual within the Umits of his heredity. Seemg that
no social amelioration can change the intrinsically bad mto
intrinsically good, we must substitute for natural selection
what D G. Ritchie so fehcitously called " rational selec-
tion " By preventing the socially unfit from propagating
their kind— whilst giving all due consideration to the unfit
themselves— the new school of eugenics, msistmg on the
hereditary factor, proposes to supplement social reform
by race culture. EUmination of the worst social types
together with selective breeding of the socially best, would
not only raise progressively the standard of the race, but
would, by reaction and counter-reaction, improve the very
methods of social endeavour. There would then be prac-
tically no limit to the achievements of the world's progress.

CONCLUSION

CHAPTER XI

THE FORMULA OF EVOLUTION

If we define philosophy with Herbert Spencer as " com-
pletely unified knowledge," then a philosophy of evolution
should consist in a unification of all the special evolutionary
processes imder one comprehensive aspect. Having re-
viewed successively the rise of the stellar world, the growth
of the earth with its elements, and the progressive evolu-
tion of plants and animal species ; having traced the slow
ascent of man from lowly beginnings to his highest mental,
moral, and social attainments, we now have to find the
common principle binding together into one whole all
these various phenomena of evolution. For, nature being
one and indivisible, it follows from the fact that evolution
is going on in all its parts, that there must be an all-
pervading law of change, holding with equal truth for the
material universe as for mankind and its social products.
The credit of having conceived the idea of such an aU-
embracing formula of evolution belongs to Herbert Spencer,
who first elaborated it fully in his epoch-making " First
Principles " (1862), which forms the basis of his great work,
the " Synthetic Philosophy." We shall foUow his account,
first giving a resume of his formula of evolution, and then
dealing with the subject of dissolution, the counterpart of

evolution. •

305 39

306 THE FIRST PRINCIPLES OF EVOLUTION

I. Evolution.
We may, to begin with, give the definition of evoludon
as expTesid by Herbert Spencer in the following short
ToTS^Evolution is an integration of matter andconcomi.
Ztssipliion of motion, during wHich the matter passes
fZi a relatively indefinite, incoherent homogeneity to a
rZively definite, coherent heterogeneity ; and durrngwhuh
tre^ned'motion undergoes ^P-^feltran^n^H^^

Seeing that an absolute state of rest does not exist m
naS ?all matter must necessarily progress towards «the^
a greater concentration or greater diffusion, the moUoj
involved being at the same time dissipated or absorbed
™ctTvely While the different parts of a given system
ma?^p IdoLinantly tend towards either the one process
Hhf other, the movement of all the parts toge he^ wUl
result in either integration or dissipation of the wMe
The Droeressive change, then, of a system from its widest
SpeS to its greafest integration constitutes the mam
phase of its evolutionary process. This I'^P^'^ J* ^f^^
a greater aggregation, i.e.. " increased closeness of juxta
poSn aL^o^g the components of the whole, and among
S: component! of each part, leading to a g-ate-oherenc
of the previously relatively incoherent mass ; but there is
dso an increase of combination, producing mutual de-
pendence of the component parts." The first law of evolu-
£n is well exemplified in the history of our solar system
We have seen that, according to modern theories, th^
sun and the attendant planets onginated from a vast
nebul" fire-mist, which, gradually cooling down and con-
densing, gave off successively the planets and their satel
fites Each of these bodies, in the course of development,
goes after its separation through the same P>^ocess °f prog^J^
five consolidation, starting as a fiery semi-flmd baU, which
^aduaUy crusts over with a hard shell, extendmg w th
timP deeper and deeper into the interior. The geological
eSuSon of th^ earth consists essentially in nothing more

THE FORMULA OF EVOLUTION 3^7

than this formation of an outer solid layer and its further
transformations. As to the organic world the law of inte-
gration manifests itself in many ways during its evolu-
tionary process, not only in the development of the indi-
vidual, but also in the progressive transmutation of species.
The living organism is essentially a machine for integrating
foodstuffs and building up organs, i.e., mutually inter-
dependent parts, out of originaUy dispersed matter the
process of integration being predominant over that of dis-
integration during the active period of life ; while a
balance on the side of disintegration during the dechn-
ing years of the organism leads to its ultimate dissolutioa
Embryonic development, too, passes through a senes of
stages, which, on the whole, are a folding-m and gathenng-
together of various ceU-masses into specific organs. The
evolution of species is characterized, generally speaking,
bv a double integration. There occurs what Spencer has
called " longitudinal integration." especially among worms
and arthropoda. The lower members possess a g^at many
successive segments, all being identical ; while m the higher
forms, as in insects, crabs, spiders, etc.. these are ^eatly
reduced in number, being modified in structure and thus
leading to a shortening and integration of the whole body
"Transverse integration " takes place in organs which are
originally double. Thus the nervous system, arranged m
tKwer organism^-on both sides of the body, becomes
united into one central organ, as we rise in the scale of
an mal beings. A similar union (at least in part) occurs in
thfie of fhe generative organs. The origination of com-
pound animals out of an agglomeration of sin^e mdmduds
furnishes a further example of organic integration. Coming
t^superorganic evolution, we find social integration w^ch
starting with the gregarious tendency among anunals, leads
n mrtrthe forTadon of tribes and their gradual consoli-
daSinto large states and nations. The orgamzation of
societv itself be it poUtical or industrial, becomes more and
i"re coSdated with the progress of dviUzation; whil.

-^r^

308 THE FIRST PRINCIPLES OF EVOLUTION

social development, again, implies an " ejeMnc^^^^^^^
ordination " of the members of society, all Imng lor ana
by one another." The intellectual and ^thet.c achieve-
ments of mankind, such as language, science art. etc
follow the same law ; but to dilate here upon this subject

would lead us too far. . ,• „ „„„

The integration of matter-which always implies a con-
comitant dissipation of motion-is the ™ phase of the
evolutionary process, and. f unaccompanied by any other
effects, it constitutes, according to Herbert Spencer
" simple evolution." But under certain conditions-when
the retained internal motion is large in quantity, or when
its dispersion is retarded-secondary changes take place
which, superadded to simple evolution, render it com-
Dound " This secondary redistribution of matter (and of
motion) consists, firstly, in a change from a homogeneous
to a heterogeneous state ;* and. secondly, in a trans t,on
from the indefinite to the definite. The tendency to hetero-
geneity naturally leads to a multiplication of parts sim-
plicity being changed to complexity. It goes without
saving that the diffused nebular state, from which the
cosmos is held to have originated, is very much more
simple in its constitution than the multifarious groups of
Jt^l planets, etc., which make up the fully evolved s.dereaJ
system. The various celestial bodies, being in all stages
of development, present among themselves great differ-
ences which were originally non-existent. Similarly, the
comparatively molten mass of the earth assumes after its
first consoUdation a more and more complex and multiform
aspect, as one geological epoch follows the other It is
however, in organic beings, which contain in their highly
complex chemical compounds a great quantity of locked-
up inotion. that the condition for compound evolution are
exceptionally favourable. It is here, in the plant and

» More correctly, from a less heterogeneous to a more hetero-
geneous state, for a condition of absolute homogeneity is unknown
to us.

THE FORMULA OF EVOLUTION

309

animal world, that we find the process of progressive differ-
entiation especially marked. Each individual, starting as
a single cell of relatively simple structure and composition,
becomes elaborated during growth into a highly complex
cell-mass with separate organs of the most vaned kind.
Parts uniform in their primordial condition, assume during
embryogenesis the most diverse forms and structures. We
only need to remember that the leaf, sepal, petal, stamen,
and carpel of a plant, all originate from identical shoots ; or
that the limbs of higher animals sprout out as little knobs
at the side of the body, being at first indistinguishable
from each other (see Fig. 36). In the evolution of society
the law of differentiation is well known as the principle of
division of labour. It is one of the most characteristic
features of the progress of civiUzation. Primitive society
is relatively homogeneous, not only in the composition of
its members, but also in its political and industrial organiza-
tion The religious and civil sides of government are still
■intimately intertWined. there being no consciousness as
vet of a possible differentiation between rehgious and
social observance. There is no sharp division between
what are now the various departments of industnal life.
" every man being warrior, hunter, toolmaker, builder,
etc. at the same time. It is only in fairiy advanced
societies that separate trades and occupations arise ; while
under modem industrialism the process of this subdivision
of labour has reached its climax by breaking up single
trades into so many separate actions. On a more abstract
Diane we see the same process of gradual differentiation m
the higher arts of man. Written language, painting,
sculpture, and architecture, so different in their modern
asp^t, can be traced back to a common origin, the crude
decorative designs of primitive man, painted or incised on
cave-walls or articles of use. Likewise poetry, music and
dancing, separate arts now, have become so only after a
long process of differentiation.
Oyming to the second phase of compound evolution, it

310 THE FIRST PRINCIPLES OF EVOLUTION

involves, as aforesaid, a change from the indefinite to the
definite. " Development, no matter of what kind, exhibits
not only a multiplication of unlike parts, but an increase
in the clearness with which these parts are marked off
from one another." It is hardly necessary to go in detail
through the whole series of natural phenomena in order to
illustrate this law. The evolution of a mist-like nebula
into distinct celestial bodies, or the further development of
a rather undefined fiery globe into a solidly limited planet
is clearly a progression from the indefinite to the definite.
Living organisms yield ample evidence of the same law in
their embryonic development, which consists in a gradual
marking-off of distinct organs from an undefined cellular
magma ; while the outstanding trait of the evolution of
species may be summed up as the disappearance of inter-
mediate forms, bringing into sharper contrast the surviving
groups. From " indistinct varieties " there are produced
" distinct species." Of the applications in the higher fields
of human achievements, we shall only mention that the
progress of science is essentially an advance from indefinite
to definite knowledge ; furthermore, the various sciences
have only gradually been delimited from the comnion
store of knowledge by a more and more precise definition
of their scope and method.

In order to complete this short survey of the formula of
evolution, we have only to add that the various changes
assumed by matter during its ascending phase also hold
good for the accompanying motion. This, too, undergoes
during the evolutionary process a parallel redistribution,
becoming more integrated, heterogeneous, and more

definite.

Herbert Spencer has gone a step further, and tried to
deduce the foregoing laws of evolution from one under-
lying principle— the cause of all evolutionary processes.
This principle is Force, which he looks upon as the ultimate
reality of existence. " To this an ultimate analysis bring^
us down, and on this a rational synthesis must build up."

THE FORMULA OF EVOLUTION

311

It is to the law of the ** Persistence of Force "* that the
change from the uniform to the multiform, and from the
indefinite to the definite, must be traced. We cannot here
enter into a detailed account of this extremely technical
subject, but may just say that the transformation of the
homogeneous into the heterogeneous is attributed by
Spencer to two results flowing from the primary law of
the persistence of force. In the first instance, the different
parts of a homogeneous whole being exposed to different
incidences of force, each part will be modified in its own
way, thus leading naturally to " the instability of the
homogeneous." Secondly, the incident force itself, origin-
ally falling uniformly on the aggregate and " differentiating
the parts on which it falls in unhke ways," is through " the
multiplication of effects " correspondingly differentiated.
Furthermore, *' the permanently effective incident force,
when wholly or partially transformed into mechanical
motion of the units, will produce like motion in units that
are alike, and unlike motion in units that are unlike."
The result is that a '* segregation " takes place whereby
the various kinds of units composing the whole are
separated from each other, the whole mass, previously
indefinite in character, thus being divided into definite,
well-defined parts. The formation of species by natural
selection is a good case in point. Organisms originally co-
mingled are segregated by the force of environmental con-
ditions into separate and distinct types.

Is there any limit to the evolutionary process just de-
scribed ? " Can things increase in heterogeneity through
all future time ? or must there be a degree which the
differentiation and integration of Matter and Motion cannot
pass V Seeing that during the ascending phase of evolu-
tion all motion is gradually dissipated, there must ulti-
mately result a state in which there is complete cessation
of motion. But this final stage of " complete equihbra-
tion " is preceded by a ** moving equihbrium," which is,

♦ Better known as the law of the Conservation of Energy.

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312 THE FIRST PRINCIPLES OF EVOLUTION

according to Spencer, a transitional condition, through
which every evolving aggregate passes. This is best illu-
trated by a spinning-top which is kept upright by its rapid
rotation round its axis. It is in a state of moving equili-
brium. When with the loss of the rotatory movement the
top, after some " wabbling," comes to rest motionless on
the ground, it is said to be in complete equilibrium. There
may arise in a system during the course of evolutionary
changes manysuch transitional kinds of moving equihbrium,
each giving place to the next, until at last final equiUbrium
is reached. That the solar system, since i ts nebular origin,
has experienced a series of mechanical readjustments, due
to the radiation of the originally contained heat, is now a
well-accepted fact of science. Furthermore, it is also
generally assumed that there must come a time— however-
far distant— when the sun's energy will be exhausted, so
that the whole solar system must inevitably tend towards
a state of complete integration and complete equilibration.
The existence of a great number of dark extinct stars
points to this conclusion. The mechanism of the moving
equilibrium is exemplified in living organisms in manifold
ways. Not only are their functions balanced from hour
to hour, from year to year, with the change of seasons, but
also by a process of slow adaptation to entirely new en-
vironmental conditions. Death in this sense must be
looked upon as the final stage of complete equilibrium.
As an example of equilibrimn in the super-organic, we shall
only mention the fact that there occurs continuous adjust-
ment between a given population and its means of sub-
sistence. As the food-supply increases, the population is
able to grow, until through its excess of numbers there is
a dearth of food, which in its turn depresses the birth-rate,
and so on alternately. The balance which in a similar way
is perpetually going on between the various animal species
living in the same neighbourhood has already been adverted
to in a previous chapter.

THE FORMULA OF EVOLUTION

2. Dissolution.

313

We have mentioned incidentally that there may go on
in different parts of an aggregate opposite movements
either towards greater integration or towards greater dis-
persion of the whole. It must now be pointed out that,
while the ascending evolutionary phase of the process
impUes a concentration of matter and dissipation of motion,
the descending phase, accompanied by an absorption of
motion, leads to a diffusion of matter, and finally to its
"dissolution." "When evolution has run its course-
when an aggregate has reached that equilibriimi in which
its changes end, it thereafter remains subject to all actions
in its envuronment which may increase the quantity of
motion it contains, and which in course of time are sure,
either slowly or suddenly, to give its parts such excess of
motion as will cause disintegration. According as its sze,
its nature, and its conditions determine, its dissolution
may come quickly or may be indefinitely postponed for
billions of years." In tracing out the process of dissolu-
tion, we may follow Herbert Spencer by starting with the
most complex phenomena, those of the social system, and
ending with the most simple those of the physical order.
While the evolution of society consists essentially in an
integration and mutual co-operation of all its constituent
parts, the reverse process of national and racial decay is
characterized by disorder, disintegration, and by the final
disappearance of the component members of society. The
life of the individual, leading from infancy to seniUty through
a series of moving equilibria, ends with the state of com-
plete equihbrium which we call " death " upon which ensues
the final disintegration of the decaying body, due to
chemical decomposition. It is a so genera ly assumed that
the earth, through a retardation of its motion, will slowly
be drawn into the sun, and thus be reduced to a gaseous
state— a fate which must happen to all the other com-
ponent bodies of our solar system. As regards the chemical

I iw uinii>M« pi 'y"<

soss

iianp

■eiW*aBasHi|«n

^^■■i«^

314 THE FIRST PRINCIPLES OF EVOLUTION

constituents of the universe, we have seen in a previous
chapter that, while there takes place during the evolution
of the stars a gradual condensation of matter, leading to
the appearance of the various chemical elements, radio-
activity shows us their dissolution, each atom being dis-
integrated into its component corpuscles.

The fina question arises: If the evolutional process
described ends everywhere in complete quiescence, what
can we say of the cosmos as a whole, holding as it does a
multitude of sidereal systems ? We have already men-
tioned that the sun must finally lose its heat and become
extinct, forming a dark star. On the other hand, celestial
bodies travelling at high velocities and colliding with
each other— an occurrence which must happen not rarely
—will inevitably be vapourized into a gaseous mass, con-
stituting what we conceive to be a nebula. As these
nebulse form once more the starting-points for new worlds,
we now see that, while there is go ng on in the universe a
process of dissolution in one place, '* a renewal of activity
and life" occurs in another. Evolution and dissolution
must thus be looked upon as alternate states embracing all

forms of existence.

Herbert Spencer's formula of evolution is so far the only
one that has been suggested to account for the totality of
natural phenomena, and we have found that within its
limits it covers a variety of facts in a truly astounding
manner. Still, grave objections have been raised against
its general validity, the main argument being that it is
based on too mechanistic an interpretation of nature.
Spencer tried to reduce all phenomena, those of the physical
world as much as those of life and society, to one under-
lying principle— that of '' the persistence of force." But,
as Professor William James has pointed out, he has by no
means worked out his fundamental assumption with consis-
tency or clearness. By persistence of force he " sometimes
means the phenomenal law of the Conservation of Energy,
sometimes the metaphysical principle that the quantity of

-I

THE FORMULA OF EVOLUTION

315

existence is unalterable, sometimes the logical pnnciple that
nothing can happen without a reason, sometimes the prac-
tical postulate that in the absence of any assignable differ-
ence you must call a thing the same." A similar objection
has to be brought against his use of the word _ force in the
realms of the organic and superorganic Vital torce,
" mental force," and " social force" were to Spencer mani-
festations of the universal force, all being in their last
source due to physical force, and " being proportionate to
the amount of physical force that is ' transformed mto
them " " What on earth is ' social force ? exclaims
Professor James. " Sometimes Spencer identifies it with
• social activities ' (showing the latter to be proportional to
the amount of food eaten), sometimes with the work done
by human beings and their steam engines, and shows it
to be due ultimately to the sun's heat. It would never
occur to a reader of his pages that a social force proper
might be anything that acted as a stimulus of social change
■ -a leader, for example, a discovery, a book, a new idea
or a national insult ; and that the greatest of ' forces of
this kind need embody no more ' physical force than the
smallest. The measure of greatness here is the effect pro-
duced on the environment, not a quantity antecedently

absorbed from physical nature."

The most thorough-going criticism, however, of the Spen-
cerian view of evolution has lately been made by Professor
Henri Bergson, who not only attacked Spencer s false
evolutionism." but elaborated at length in his C^ative
Evolution " (1907, English translation 1911), a philosophy
of change " of high originaUty, which certainly has opened
an entirely fresh outlook upon the problem of life and the
universe.

g*5g

CHAPTER XII

THE PHILOSOPHY OF CHANGE

Bergson's view ol evolution is intimately bound up with
his general conception of life. It forms part and parcel of
his philosophy. It is necessary, therefore, in order that
we may fully understand his views, to make ourselves ac-
quainted—at least cursorily— with the fundamental ideas
of his writings. Bergson is, as we have mentioned in a
previous chapter, a vitalist, i.e., he sees in life a phenomenon
sui generis, which cannot be accounted for by mechanical
causes. But more than this : to him life is the only reality ;
it progresses and endures in time, being a ceaseless move-
ment of perpetual becoming, a continuous upspringing of
new, unforeseeable forms. It is this new creation— this
" creative evolution " — ^which is the essential characteristic
of all living existence. Life is, according to this view, not
a series of successive states, but a single flux, an indivisible
continuity — duration itself.

To understand evolution in the Bergsonian sense, we
must try to grasp this endless flow of reality in its inner-
most meaning. It is here that Bergson's attack on the
Spencerian evolutionism is most successful. He shows
that Spencer, enmeshed in his mechanistic method, only
got hold of the outward appearance of evolution. False
evolutionism cuts up real becoming into a succession of
discontinuous, fixed states, and by stringing them together
end to end imagines that it thereby reconstructs the whole
movement. But, as Bergson says : " It is not by dividing
the evolved that we shall reach the principle of that which

316

THE PHILOSOPHY OF CHANGE

317

\ »i

evolves. It is not by recomposing the evolved with itself
that we shall reproduce the evolution of which it is the
term." We may divide up in this w^ay the whole move-
ment as often as we like ; we shall never by this means lay
hold of the actual interval of duration — change itself.
Bergson goes on to elucidate most beautifully how the
whole natural bent of man's intellect has been moulded
into the direction of this mechanistic interpretation of
nature. " Intellect is never quite at home, except when
it is working upon inert matter. ... Of the discontinuous
alone does the intellect form a clear idea. ... It cannot,
without reversing its natural direction and twisting about
on itself, think true continuity, real mobility, reciprocal
penetration — ^in a word, that creative evolution which is
life."

And the reason for this is that human intellect was not
made intrinsically for speculative philosophy, for the
understanding of the universe, but was evolved for the
practical purposes of life — to orient our existence in the
material world. In fact, in Bergson's view our intellect
cuts out of the flux of existence, according to our needs of
action, the very forms we call material objects. Being
made for the inorganized, it is " characterized by a natural
inability to comprehend life." It therefore deals — ^as all
science must do — ^with life in a mechanical way, and repre-
sents becoming by a series of states, the result being that,
" though we may do our best to imitate the mobility of
becoming by an addition that is ever going on, becoming
itself slips through our fingers just when we think we are
holding it tight."

This mechanistic illusion of change Bergson has most
happily illustrated by likening our method of thought to
the cinematographical reproduction of life. Just as the
cinematograph fUm only represents a series of snapshots,
each giving an immobile picture, so our intellect merely
takes stable views — cuts made across the background of a
continuous flux. Intellect shows us no change, but a sue-

3i8 THE FIRST PRINCIPLES OF EVOLUTION

cession of states. " The Forms, which the mind isolates
and stores up in concepts, are only snapshots of the changing
reality/' In order to restore life to the cinematograph
picture, we must add movement by a rapid rolling off of
the picture film ; similarly, in order " to instal ourselves in
becoming," we must " see in duration the very life of things,
the fundamental reality."

We cannot but admire Bergson's penetrative insight in
dealing with the problem of life. He seems to go to the
very heart of the matter, and certainly has revealed an
aspect of evolution which is as startling as it is profound.
If we have had before a science of evolution, Spencer's
" Synthetic Philosophy" not excluded, Bergson has given
us for the first time a real *' philosophy of change."

There is left one final question : Seeing that life transcends
intellect, intellect being limited to a mere " instantaneous "
view of life, how can we get at the real inwardness of its
flowing reality ? Bergson's answer is : By intuition ; not
by intuition in the sense of the exceptional gift of the seer,
but, as C. Wildon Carr has expressed it, by " that sym-
pathetic attitude to the reality without us that makes us
seem to enter it, to be one with it, to live it. . . . It is so
identical with life itself that wherever there is life there
might also be that consciousness of living that is intuition."

How far this solution is a real one is too speculative a
point to be raised in its fulness at this juncture. We have,
in a previous chapter, adverted to the fact that " sym-
pathy " cannot explain instinct, to which it is supposed to
be akin ; and it must remain a moot point whether intuition
is sufficient to illuminate life as a whole in order to bring
it effectively to our cognizance. The whole problem is
more a matter for the philosophical student than for the
scientist. Indeed, Bergson's ingenious work has shown
that a true theory of life and a theory of knowledge are in
their fundamentals interdependent. It is in the field of
metaphysics rather than that of biology that the riddle of
evolution will have to find its final solution.

i I

LITERATURE*

{Italics denote that the work has been previously mentioned

in the List.)

COSMIC EVOLUTION.

Sir Robert Ball: The Earth's Beginning. London, 1909.
G. E. Hale : The Study of Stellar Evolution. Chicago, 1908.
Chamberlin and Salisbury : Geology. Vol. II. London, 1906.
Sir N. Lockyer : The Meteoritic Hypothesis. London, 1890.

GEOLOGICAL EVOLUTION.

Sir a. Geikie : Textbook of Geology. London. 1903.
Chamberlin and Salisbury : Geology. 3 vols. London, 1906.
W. J. SoLLAS : The Age of the Earth. New edition. London. 191 2.

ATOMIC EVOLUTION.

R. K. Duncan : The New Knowledge. London, 1907.
Sir N. Lockyer: Inorganic Evolution. London, 1900.
F. SoDDY : The Interpretation of Radium. London, 1909.
Sir J. J. Thomson : Electricity and Matter. London, 1904.

EVOLUTION OF LIFE.

Max Verworn : General Physiology. London. 1899.

Oliver Lodge : Life and Matter. London. 1909.

J. A. Thomson : Introduction to Science. London. 191 1.

Benjamin Moore : The Origin and Nature of Life. London. 191 3.

* The list of books is not exhaustive. It is intended merely as a
first guide to the literature of each subject.

319

mrnmr

320 THE FIRST PRINCIPLES OF EVOLUTION

ORGANIC EVOLUTION.
(General Books.)

Charles Darwin : The Origin of Species. Sixth edition. London,

1872.
A. R. Wallace: Darwinism. London, 1889.
Herbert Spencer : The Principles of Biology. New edition.

London, 1898.
Ernst Haeckel : Natural History of Creation. Fourth edition.

London, 1899.
A. Weismann : The Evolution Theory. London, 1904.
G. J. Romanes : Darwin and after Darwin. 3 vols. London, 1897.

MORPHOLOGY.

Charles Darwin : The Descent of Man. Second edition.

1896.
Darwin : Origin of Species.
Weismann : Evolution Theory, Vol. I.
Romanes : Darwin and after Darwin, Vol. I.

EMBRYOLOGY.

E. Haeckel : The Evolution of Man. London, 1906.
Darwin : Origin of Species.
Haeckel: History of Creation, Vol. I.
Weismann : Evolution Theory, Vol. II.
Romanes : Darwin and after Darwin, Vol. I.

CLASSIFICATION.

J. A. Thomson : The Science of Life. London. 1899.

Darwin : Origin of Species.

Spencer : Principles of Biology, Vol. I.

Haeckel : History of Creation, Vol. II.

Romanes : Darwin and after Darwin, Vol. I.

PALEONTOLOGY.

Darwin : Origin of Species.

Wallace : Darwinism.

Spencer : Principles of Biology, Vol. I.

Romanes : Darwin and after Darwin, Vol. I.

London,

. ,. .r, ^ .^.:.;..at,.--"ft:Aa.Jit>£

LiTERAtURE 321

GEOGRAPHICAL DISTRIBUTION.

A. R. Wallace : Island-Life. London, 1 880.

Darwin : Origin of Species.

Wallace : Darwinism.

Spencer : Principles of Biology, Vol. I.

Romanes : Darwin and after Darwin, Vol. I.

HISTORY OF EVOLUTION.

E. Clodd : Pioneers of Evolution. London, 1902.

H. F. Osborn : From the Greeks to Darwin. New York, 1894.
Haeckel : History of Creation, Vol. I.
Thomson : Science of Life.

LAMARCKISM.

A. S. Packard : Lamarck, his Life and Work. London, 1901.
G. Henslow : The Origin of Plant-Structures. London, 1895.
G. Henslow : The Origin of Floral-Structures. London, 1888.

NATURAL SELECTION.

Darwin : Origin of Species.

Wallace : Darwinism.

Weismann : Evolution Theory, Vol. I.

Romanes : Darwin and after Darwin, Vol. I.

PLANT-STRUCTURES.

Darwin : Origin of Species.

Wallace : Darwinism.

Weismann : Evolution Theory, Vol. I.

Charles Darwin : The various special works on plants.

ANIMAL COLOURATION.

Wallace : Darwinism,

Weismann : Evolution Theory, Vol. I.

F. E. Beddard : Animal Coloration. London, 1892.

E. B. Poulton : The Colours of Animals. London, 1 890.

INSTINCT.

Darwin : Origin of Species.
Weismann : Evolution Theory, Vol. I.
Romanes : Darwin and after Darwin, Vol. II.
Lloyd Morgan : Habit and Instinct. London, 1896.

322 THE FIRST PRINCIPLES OF EVOLUTION

HUMAN FACULTY.

Wallace : Darwinism.

Romanes : Darwin and after Darwin, Vol. II.

A. R. Wallace : Natural Selection and Tropical Nature. London.

A. WmsMANN : Essays on Heredity (see Thoughts on Nature of
Music). Oxford, 1891.

DEGENERATION.
Sir E. R. Lankester : Degeneration. London. 1880.

SEXUAL SELECTION.

Darwin : Descent of Man.

Wallace : Darwinism.

Romanes : Darwin and after Darwin, Vol. I.

Beddard : Animal Coloration.

PouLTON : Colours of A nimals.

Lloyd Morgan : Animal Life and Intelligence. London, 1890.

neo-lamarckism versus NEO-DARWINISM.
V. L. Kellogg: Darwinism To-Day. London, 1907. (With

extensive bibliography.) . .

L. Plate : Selectionsprinzip und Probleme der Entartung. Leipzig,

1908.
Darwin : Origin of Species.

Wallace : Darwinism. , c , x-

Spencer : Principles of Biology. (Inadequacy of Natural Selection,

etc.)
Romanes : Darwin and after Darwin, Vol. U.

PANMIXIA.

A. Weismann : Essays on Heredity.
Romanes : Darwin and after Darwin, Vol. II.
Kellogg : Darwinism To-Day.
Plate : Selectionsprinzip.

INTRA-SELECTION.

W. Roux : Der Kampf der Telle im Organismus.
Weismann : Evolution Theory.
Kellogg : Darwinism To-Day.
Plate : Selectionsprinzip.

Leipzig, 1 88 1.

LITERATURE 323

GERMINAL SELECTION.

A. Weismann : On Germinal Selection. Chicago. 1896.
Weismann : Evolution Theory.

Kellogg : Darwinism To-Day. ■■

Plate : Selectionsprinzip.

COINCIDENT SELECTION.

J. M. Baldwin : Development and Evolution. New York. 1902.
Lloyd Morgan : Habit and Instinct.
Kellogg : Darwinism To-Day.
Plate : Selectionsprinzip.

ISOLATION.

Wallace : Darwinism.

Romanes : Darwin and after Darwin, Vol. 111.

Weismann : Evolution Theory.

Kellogg : Darwinism To-Day.

Plate : Selectionsprinzip.

Lloyd Morgan : Animal Life and Intelligence.

HETEROGENESIS.
HUGO DE VRiEs : Species and Varieties : their Origin by Mutation.
HoG^orv^R^ET^X^S^ HngUshedition. London.

TH. H. MORGAN : Evolution and Adaptation. New York. 1908.
Kellogg : Darwinism To-Day.

wTxTHSor M^tlS^L the Study of Variation. London. ,894.
W. JOHAKNSBK Ueber ErbUchkeit in Populationen und reinen
Linien. Jena, 1903.

ORTHOGENESIS.

G H Th.Eimbr: Organic Evolution. London, 1890.

?•' H Th Eimer • On Orthogenesis. Chicago, 1898.

E. S: ?oPB ThVpSmary pfctors of Organic Evolution. Chicago.

E. D.?oPB : The Origin of the Fittest. New York, 1 887.

324 THE FIRST PRINCIPLES OF EVOLUTION

VITALISM.

Oliver Lodge : Life and Matter.

H. Driesch: The Science and Philosophy of the Organism.

London, 1908. . .

GusTAV Wolff : Mechanismus und Vitalismus. Leipzig. 1905.
A. Pauly : Darwinismus und Lamarckismus. Munich, 1905.
J. Reinke : Einleitung in die theoretische Biologie. Berlin, 191 1 .
Henri Bergson : Creative Evolution. London, 191 1.

MENTAL EVOLUTION.

Herbert Spencer : The Principles of Psychology. Fourth edition.

London, 1899.
J LoEB : Der Heliotropismus der Tiere. Wurzburg, 1890.
j! LoEB : Die Bedeutung der Tropismen fur die Psychologic.

Leipzig, 1909. , XT xr 1

H. S. Jennings : Behavior of the Lower Organisms. New York.

1906.
G Bohn : La Naissance de 1' Intelligence. Paris, 1910.
Lloyd Morgan : Animal Behaviour. Second edition. London,

1908.
G. J. Romanes : Mental Evolution in Animals. London, 1883.
g! J. Romanes : Mental Evolution in Man : London, 1888.
L. T. HoBHOUSE : Mind in Evolution. London. 1901.
Bergson : Creative Evolution.

MORAL EVOLUTION.

Darwin : Descent of Man.

Herbert Spencer : The Principles of Ethics. London, 1897.

A. Sutherland : The Origin and Growth of the Moral Instinct.

London, 1898.
Lloyd Morgan : Animal Behaviour.

A. E. Taylor : The Problem of Conduct. London. 1901.
L. T. Hobhouse : Morals in Evolution. London, 1906.
E. Westermarck : The Origin and Development of the Moral Ideas.

London, 1906. _ ^ x ^

T. H. Green: Prolegomena to Ethics. Fifth edition. Oxford

1906.
W. R. SoRLEY : The Ethics of Naturalism. Second edition.

London, 1904.
W. R. SoRLEY : Recent Tendencies in Ethics; London, 1904.
Th. H. Huxley : Evolution and Ethics. London, 1894.

LITERATURE

EVOLUTION OF MAN.

325

Darwin : Descent of Man,

Th. H. Huxley : Man's Place in Nature. London, 1897.

Haeckei. : History of Creation.

W. Boyd Dawkins : Eariy Man in Britain. London. 1880.

Sir John Lubbock : Prehistoric Times. London. New edition.

1912.
A. H. Keane : Ethnology. Cambridge, 1909.

London.

London,

EVOLUTION OF MARRIAGE.

Darwin: Descent of Man.

Herbert Spencer : The Principles of Sociology, Vol. l.

1893.
G. E. Howard : A History of Matrimonial Institutions.

1904. (With extensive bibliography.)

Sir H. S. Maine : Ancient Law. London, 1861.

L. H. Morgan : Ancient Society. London, 1877.

J. F. McLennan : Studies in Ancient History. New edition,

London, 1886. . ,

E. Westermarck : The History of Human Marriage. London,

1891.

EVOLUTION OF THE STATE.

Herbert Spencer : The Principles of Sociology. 3 vols. London,

1893.
L. T. Hobhouse : Morals in Evolution, Vol. I.
E. A. Freeman : Comparative Politics. London, 1874.
E. JENKS : A History of Politics. London, 1900.
A. Sutherland : Origin and Growth of Moral Instinct.
FusTEL DE Coulanges : Ancient City. Boston. 1874.
H. DE B. GiBBiNS : Industry in England, London, 1896.
H. W. Nevinson : The Growth of Freedom. London, 191 2.

PRIMITIVE COMMUNISM.

Sir H. S. Maine : Ancient Law.

Sir H S. Maine : Early History of Institutions. London, 1875.

Sir H. S. Maine : Village Communities in the East and West.

Third edition. London, 1876.
E. DE Laveleye : On Property and its Primitive Forms. London.

1878.
P. Lafargue : The Evolution of Property. Fifth edition. London.

1908.

-jijiy.

326 THE FIRST PRINCIPLES OF EVOLUTION

B. H. Baden-Powell: Village Communities in India. London,

1899.
FusTEL DE CouLANGEs : The Origin of Property in Land. London.

1891.

FEUDALISM.

Sir H. S. Maine : Early History of Institutions.

Sir H. S. Maine : Village Communities in the East and West.

P. Lafargue : Evolution of Property.

J. F. Abdy : Lectures on Feudalism. London, 1890.

EVOLUTION OF RELIGION.

Edward Clodd : Animism. London, 1905.

E. B. Tylor : Primitive Culture. London, 1871.

Herbert Spencer : The Principles of Sociology, Vols. I and III.

L. T. Hobhouse : Morals in Evolution, Vol. II.

J. G. Frazer : The Golden Bough. Second edition. London, 1900.

F. Max MxJller : Natural Religion. London, 1889.
F. Max Muller : Physical Religion. London, 1891.

F. B. JEVONS : Introduction to the History of Religion. London,

1896.
W. Robertson Smith : Lectures on the Religion of the Semites.

London, 1894.

Andrew Lang : The Making of Religion. Second edition. Lon-
don, 1900.

E. Crawley : The Tree of Life. London, 1905.

EVOLUTION AND PROGRESS.

D. G. Ritchie : Darwinism and PoUtics. Second edition. London,

1891.
D. G. Ritchie : Studies in Political and Social Ethics. London,

1902.
L. T. Hobhouse : Social Evolution and Political Theory. London,

1911.

G. Archdall Reid : The Present Evolution of Man. London, 1896.
J. B. Haycraft : Darwinism and Race- Progress. London. 1895.
Sir Francis Galton : Essays in Eugenics. London, 1909.

PHILOSOPHY OF EVOLUTION.

Herbert Spencer : First Principles. Sixth edition. London, 1900.
Henri Bergson : Creative Evolution.

H. Wildon Carr: Henri Bergson, The Philosophy of Change.
London, 1912,

^*«^

GLOSSARY

[L means derived from Latin ; Gr. means derived from Greek.
The pages refer to the context of the book, where the word is
explained.]

Abiogenesis (Gr. a, negative; bios, life; genesis, birth) (p. 43).
Agnation (L. ad, to; nasci. to be bom), relationship through the

male line (p. 273). ^ • • +

Agnostic (Gr. a, negative; gnosticos, good at knowmg) , pertammg to
the belief that the essence of nature is unknown and perhaps
unknowable.
Alga (L. alga, sea-weed), a division of plants embracing sea-weeds.
Alogical (Gr. a, negative; logicos, reasonable), not amenable to

reason.
Amixia (Gr. a, negative; mixis, a mingling) (p. 199)-
Amoeba (Gr. amcsbe, change), the lowest single-celled ammal con-
stantly changing its form.
Amoebina (see Amoeba), amoeba-like single-celled animal.
Amphibian (Gr. amphi, both; bios, life), animals capable of living

both in water and on land, as frogs, etc.
Amphioxus (Gr. amphi, both; oxys. sharp), the lane elet fish, pointed

at both ends.
Analogous (Gr. ana, according to; logos, reason) (p. 52).
Angiosperms (Gr. angeion, a case; sperme, a seed), plants with

enclosed seeds.
Angiospores (Gr. angeion, a case; sporos, a seed), plants with en-
closed spores.
Animism (L. anima, soul) (p. 289).
Antenna (L. antenna, the projecting yard of a sail), the feeler of an

insect.
Anther (Gr. antheros. flowery), the top of the stamens in a flower,

containing the pollen.
Anthropoid (Gr. anthropos, man; eidos, form), man-like.
Anthropomorphism, AnthroFOmorphiO vCir. anthropos. man; rnorphe,

form), the viewing of natuiciiom a merely human standpoint.

327

328 THE FIRST PRINCIPLES OF EVOLUTION

Aphrodisian (Gr. Aphrodite, the goddess of love), devoted to sensual

AplacentalS (Gr. a, negative; L. placenta, a flat cake), animals
having no placenta, and bringing forth immature young.

Apogamy (Gr. apo, away; gamos, marriage) (p. 200).

Apteryx (Gr. a. negative; pteryx, wing), a wingless and tailless bird
of New Zealand.

Archssan (Gr. archaios, ancient) (p. 24).

Archaeoptcryx (Gr. archaios, ancient; pteryx, wing) (p. 94)-

Archasthetism (Gr. archos, first; aisthesis, perception) (p. 217).

Archebiosis (Gr. arche. beginning; bios, life) (p. 46)- .

Archetype (Gr. arche, beginning; typos, a model), an original mode .

Arthropoda (Gr. arthron, joint; pous, pod-, foot), a class of animals
with jointed feet, as insects, crabs, etc.

Assimilation (L, ad, to; similis, like), the process of likemng. com-

Astrophysi^' (Gr. astron, star; physikos, natural), the study of the

physical structure of the stars.
Atavistic (L. atavus, a great-grandfather), reverting to an ancestral

type.
Atom, Atomic (Gr. a, negative; temnetn, to cut) (p. 30).
Atrophy (Gr. a, negative; trophe, nourishment), a wasting.
Autonomic (Gr. autos. self; nomos, law), having its law withm itself,

self-governing.

Bacteria (Gr. bakterion, a little stick), lowest single-celled plant-
organisms. , . , . , J
Batrachians (Gr. batrachos, a frog), the order of reptilia which includes

the frogs, etc.

Biogenesis, Biogenetic (Gr. bios, life; genesis, birth) (p. 43).

Biometrician (Gr. bios, life; metron, measure), a student of bio-
metrics, the statistical science of life.

Blastnla (Gr. blastos. germ) (p. 73).

Cambrian (pertaining to Cambria-i.^.. Wales), geological strata

first found in Wales.
Carbohydrates (L. carbo, coal; Gr. hydOr, water), organic compounds

of carbon with oxygen and hydrogen in the proportion of

water, as. e.g., sugar, starch, etc.
CarbonilerOUS (L. carbo, coal; ferre, to bear), producing coal.
Catastrophism (Gr. kata, down; strephein. to turn), the hypothesis

of catastrophic or revolutionary changes in geology.
Cathode (Gr. kata, down; hodos. way) (p. 35)-
Cenogeny, Oenogenetic (Gr. kainos, recent; genesis, birth) (p. 79).

GLOSSARY

329

Cenozoic (Gr. kainos, recent; zoon, animal) (p. 23).
Chemotropism (chemical and tropism) (p. 228).
Cilia (L, cilium, an eyelash), hair-like lashes borne by cells.
Coccygeal (Gr. kokkyx, the cuckoo), relating to the lowest bone of

the vertebral column.
Coelenterata (Gr. koilos, hollow; enteron, intestine), a class of lower

many-celled animals.
Coelom (Gr. koilos, hollow) (p. 73).
Coelomula (Gr. koilos, hollow) (p. 72).

Cognation (L. co-, together; natus, born), of the same family (p. 273).
Colloid (Gr. kolla, glue; eidos, form) (p. 44).
Communism, Communistic (L. communis, common), the common

ownership of the means of production, with common use of

products.
Concept, Conceptual (L. concipere, to conceive), an abstract idea.
Copulation (L. co-, together; apere, to join), the process of sexual

union.
Corolla (L. diminutive of corona, a crown), the inner circle of the

floral envelope, generally of bright colour.
Corpuscle (L. corpusculum, a little body) (p. 35).
Cretaceous (L. creta, chalk) (p. 27).
Crustacea (L. crusta, a crust), a large class of animals, including

lobsters, crabs, etc.
Cryptogams (Gr. kryptos, concealed; gamos, marriage), flowerless

plants with concealed fructification.

Determinants (L. determinare, to determine) (p. 195).

Devonian (belonging to Devonshire), strata abounding in Devon-
shire.

Dicotyledon (Gr. di-, two; kdtyledon, cavity), a plant having two
seed-lobes.

Dimorphic (Gr. di-, twice; morphe, form), with double form.

Diphycercal (Gr. diphyes, of double nature; kerkos, tail) (p. 96).

Dominant (L. dominare, to be master), to be predominant (p. 189).

Dorsal (L. dorsum, the back), belonging to the back.

Dynamic (Gr. dynamikos, powerful), pertaining to force producing
motion.

Echinodermata (Gr. echinos, a hedgehog; derma, skin), a class of
lower animals having their skin covered with spines.

EiCtoderm (Gr. ektos, outside; derma, skin), the external layer of the
embryo.

Edentates (L. e-, out of; dens, tooth), an order of mammals having
no teeth.

i1
-I

330 THE FIRST PRINCIPLES OF EVOLUTION

Emanation (L. e-, out; manare, to flow) (p. 37)-

Embryo, Embryonic (Gr. embryon). the young orgauism m its earliest

stages of development.
Embryogenesis or Embryogeny (Gr. embryon; genesis, generation),

the development of the embryo.
Embryology (Gr. embryon ; logos, a discourse), the science of the

development of the embryo.
Enteleohy (Gr. en, in; telos, end; echein, to have) (p. 220).
Entoderm (Gr. entos, within; derma, skin).
Eocene (Gr. eos, dawn; kainos, new) (p. 27).
Eolith, Eolithic (Gr. eos, dawn; lithos. stone) (p. 261).
Engenics (Gr. eu, well; genes, producing) (p. 304)-
Exogamy (Gr. exos. out; gamos, marriage), marriage outside ones

own tribe (p. 276).

Finalism (L. finis, end), the theory that the universe has a final

purpose.
Fission (L. findere, to cleave), division (p. 44).
Flagellate {h.flagellum. a little whip), a single-celled orgamsm.
Foetus {h.feuere, to bring forth), the young in the womb m its later

staces

ForaminifOTa (L. foramen, hole; ferre, to bear), orders of lower
animals generally perforated with pores.*

Fungi (L. fungus, a mushroom), one of the lowest class of plant-
organisms.

Gasteropod (Gr. gaster, the belly ; pous, pod-, a foot), molluscs having
a muscular disc under the belly, which serves them as feet.

Oastrsea (Gr. gaster, the belly) (p. 75)-

Gastrula (Gr. gaster, the belly) (p. 73)-

Genepistasis (Gr. genes, being born; epistasts, a standstill) (p. 217).

Genesis (Gr. a begetting), production.

Geocentric (Gr. ge, earth; kentron, a centre), having the earth for
its centre.

Germinal (L. germen, a bud), pertaining to the germ-cells.

Gestation (L. gestare, to bear), the bearing of the young m the womb.

Gymnosperms (Gr. gymnos, naked; sperma, seed), plants with naked

seeds
Gymnospores (Gr. gymnos, naked; sporos. a seed), plants with naked

spores.
Gynocracy (Gr. gyni, woman; kratos, power), government by women.

Heliocentric (Gr. heiios, the sun; kentron, the centre), having the
sun as a centre.

GLOSSARY

331

Heliotropism (Gr. heiios, the sun; tropos, a turn), the tendency to

turn towards the light (p. 228).
Henotheism (Gr. heis, hen-, one; theos, god) (p. 292).
Hetairism (Gr. hetaira, a female companion), concubinage.
Heterocercal (Gr. heteros, difiEerent from; kerkos, tail) (p. 96).
Heterogeneity (Gr. heteros, different from; genos, kind), composition

from different parts.
Heterogenesis (Gr. heteros. other; genesis, generation) (p. 206).
Heterostylism (Gr. heteros, other; stylos, a. piUai) (p. 129).
Histonal (Gr. histos, a web), pertaining to tissues.
Homocercal (Gr. homos, the same; kerkos, tail) (p. 96).
Homogamy (Gr. homos, the same; gamos, marriage) (p. 200).
Homogeneity (Gr. homos, the same; genos, kind), composition from

parts of the same kind.
Homologous (Gr. homos, the same; logos, ratio) (p. 52).
Hydrosphere (Gr. hyddr, water; sphaird, ball), the water surrounding

the earth's surface.

Idealist (Gr. id^a, a general form or idea), pertaining to idealism
or the theory according to which the universe must be referred

to ideas only. . ^ ^, r

Ideational (Gr. idH, a general form or idea), referring to the forma-
tion of ideas. , ■, - j. 4.

lufusorian (L. in, into: fundere, to pour), protozoa found in stagnant
infusions of animal and vegetable matter.

Integration (L.m^^^rare), to make whole (p. 307).

Intra-uterine (L. intra, within; uterus, the womb), within the womb.

Intuition, Intuitionist (L. in, into; tueri, to look), immediate per-
ception of knowledge.

Invertebrate (L. in, negative; vertebra, the bone of the spine), with-
out a backbone.

Jurassic, geological strata well developed in the Jura Mountains.

Kinetogenesis (Gr. kinetos, movable; genesis, birth), origination of
animal structure in animal movements.

Lepidoptera (Gr. lepis, a scale ; pteron, a wing), insects with four

wings covered with scales, as butterflies, moths, etc.
Levirate (L. levir, a brother-in-law) (p. 276). / ^ ,,

Lithosphere (Gr. lithos. a stone; sphaira. a ball), the crust of the
earth.

r^i^^

332 THE FIRST PRINCIPLES OF EVOLUTION

Mamma (L.), breast.

Mammals, Mammalian (L. mamma, breast), animals having breasts

and suckling their young.
Blandible (L. mandere, to chew), jawbone.
Marsapial (Gr. marsupion, a pouch), carrying young in a pouch, as

the kangaroo.
Matriarchate, Matriarchal (Gr. meter, mother; archos, a ruler),

government by a mother (p. 274).
Maxilla, Maxillary (L.), jawbone.
Megatherium (Gr. megas, large; therion, wild beast), a gigantic

extinct quadruped.
Mendelian. referring to Mendel, the founder of a theory of heredity

(p. 189).
Mendelize, to conform to the Mendelian law of heredity (p. 211).
Mesozoic (Gr. mesos, middle ;^2:oe, life) (p. 27).
Metabolic (Gr. metabole. a change), referring to metabolism— i^.,

the sum of chemical changes within the living organism.
Metamorphosis (Gr. meta, expressing change; morphe, form), trans-
formation.
Metaphysical (Gr. meta, after; physika, physics), relating to meta-
physics, the philosophy of first principles.
Miocene (Gr. melon, less; kainos, recent) (p. 27).
Molecalar (L. moles, mass), consisting of molecules, a molecule being

the smallest chemical mass.
Molluscs (L. moUuscus, softish), a large division of invertebrates, as

snails, cuttle-fish, etc.
Monism (Gr. monos, alone), the philosophical theory that all being

may ultimately be referred to one entity.
Monocotyledons (Gr. monos. alone; kotyUdOn, cavity), plants having

one seed-lobe.
Monogamian, Monogamous (Gr. monos, one; gamos, marriage),

relating to monogamy, the marriage between one man and

one woman.
Monogenist (Gr. monos, one; genos, kind), believer in the descent of

the whole human family from a single pair.
Monotheism (Gr. monos, one; theos, god), belief in only one

God.
Monotremata (Gr. monos, one; trema, hole), the lowest order of

mammals having a single opening for the genital and digestive

organs.
MonotypiC (Gr. monos, one; typos, type) (p. 189).
Morphology, Morphological (Gr. morphe, form; logos, discourse),

the science of organic forms.
Morula (L. morum, mulberry) (p. 72).

->i

GLOSSARY

333

Motor nerves (L. movere, motus, to move), the nerves which move the

muscles of the body.
MulticeUular (L. multus, many; cella, cell), consisting of many cells.
Mutant, Mutation (L. mutare, to change) (p. 210).

Neo-Darwinism (Gr. neos, new; and Darwinism) (p. 178).

Neo-Lamarckism (Gr. neos, new; and Lamarckism) (p. 175).

Neolithic (Gr. neos, new; lithos, stone) (p. 261).

Neo-Vitalism, Neo-vitalist (Gr. neos, new; L. vita, life) (p. 219).

Neptunist (L. Neptunus, god of the sea) (p. 18).

Neural (Gr. neuron, nerve), pertaining to a nervous change.

Neurosis (Gr. neuron, nerve), a change in nerve-cells.

Nitrogenous (Gr. nitron, soda; gennain, to generate), possessmg
nitrogen, which is an essential constituent of living matter.

Non-placental (L. non, not; placenta, a flat cake), having no placenta,
as the lower orders of mammals.

Notochord (Gr. notos, the back; chorde, string), a cellular rod form-
ing the basis of the future spinal column.

Nucleus, Nuclelous (L. nux, a nut), a central mass, a special part of the
cell (p. 70).

Oligocene (Gr. oHgos, little; kainos, new) (p. 27).

Ontogeny, ontogenetic (Gr. on, ont-, being; genesis, generation), the

individual development of an organism (p. 61).
Orthogenesis (Gr. orthos, straight; genesis, generation) (p. 214).
Orthoplasy (Gr. orthos, straight; plasis. formation) (p. 183).
Orthoselection (Gr. orthos, straight; and selection) (p. 214).
Ovum (L.), egg (p. 70).

Paleeolithic (Gr. palaios, ancient; lithos, stone) (p. 261).
Palfieontology, Palceontological (Gr. palaios. ancient; onta, existences;

logos, discourse), the science of ancient hfe on earth.
Palseozoic (Gr. palaios, ancient; zoe. life) (p. 23).
Palingeny (Gr. palin, again; genesis, generation) (p. 79).
Panmixia (Gr. pan, all; mixis, mingling) (p. 186).
Parturition (L. parturlre, to bring forth), the act of bringing forth

young. -

Patriarchate, Patriarchal (Gr. pater, father; archos, a ruler), govern-
ment by the house-father (p. 272).

Permian, pertaining to Perm, a province in Russia, where the strata
are extensively developed.

Phallic (Gr. phallos, the male sex-organ), relating to the phallus.

Phanerogams (Gr. phaneros. visible; gamos, marriage), plants having
true flowers with stamens and pistils.

334 THE FIRST PRINCIPLES OF EVOLUTION

Photochemical (Gr. phos, light ; and chemical), pertaining to the

chemical action of light.
Phyletic (Gr. phyle, tribe), pertaining to a tribe.
PhylOgeny (Gr. phylon, race; genesis, generation), the development

of the race.
Physiogenesis (Gr. physis, nature; genesis, generation) (p. 217).
Pistil (L. pistillum, a pestle), the female organ of a flower.
Placental (l-. placenta, a flat cake), mammals having a placenta,

by means of which the unborn young is nourished in the

womb.
Planetesimal, Planetesimal (Gr. pianetes, a wanderer), a body like a

planet (p. 15).
Planetoid (Gr. pianetes, a wanderer; eidos, form), a body like a planet

(p. 15)-
Pleistocene (Gr. pleistos, most; kainos, recent) (p. 28).

Pliocene (Gr. pleion, more; kainos, recent) (p. 27).

Polyandry (Gr. polys, many; aner, andr-, man), union of one woman

with many husbands.
Polygamy (Gr. polys, many; gamos, marriage), the practice of having

more than one wife at the same time.
Polygenist (Gr. poly, many; genos, kind), a believer in the multiple

genesis of man.
Polygyny (Gr. poly, many; gyne, woman), the union of one man

with many women.
Polyp (Gr. polys, many; pous, foot), an animal like the fresh-water

hydra.
Polytheistic (Gr. polys, many; theos, god), relating to the belief in

many gods.
Polytypic (Gr. polys, many; typos, type) (p. 189).
Precambrian (L. pree, before; and Cambrian) (p. 24).
Primates (L. primus, first) (p. 85).
Promiscuity (L. pro, intensifying; misare, to mix), promiscuous

sexual intercourse.
Proteid (Gr. protos, first; eidos, form), a body containing protein,

formerly supposed to be the basis of the most essential food

substances, albumin, etc.
ProterOZOic (Gr. proteros, fore; zoe, life) (p. 24).
Proto-metal (Gr. protos, first; and metal) (p. 33).
Protoplasm (Gr. protos, first; plasma, form), the substance forming

living matter.
Protozoa (G. protos, first; zodn, animal), the lowest one-celled

animals.
Psychosis (Gr. psych'e, the soul), a state of consciousness.
Ptolemeean, pertaining to Ptolemy (a.d. 139).

GLOSSARY

335

Recessive (L. recessus. a going back), receding (p. 189).
Reflex (L. re, back; flectere, bend) (p. 228).

Retrogression (L. retro, backwards; gradi, gressus, to go), a decline.
Rudiment, Rudimentary (L. rudimentum, a first beginning), an un-
developed or dwindled part (p. 59)-

Sacrum (L. sacrum, sacred— namely, bone), the triangular bone

situate at the lower part of the vertebral column.
Saltatory (L. saltare. to leap), leaping.
Segregation (L. se. aside; grex, flock), separation (p. 311).
Sensori-motor (sensory and motor), pertaining to sensation and

motion. • .i. •

Sensory nerves (L. sentire. to feel), the nerves which receive the im-
pressions made on the senses.

Sflurian, belonging to Siluria. the country of the Silures. the ancient
inhabitants of the south-eastern part of Wales (p. 25).

Simian (L. simia. ape), like an ape.

Somatic (Gr. soma, body), pertaining to the body.

Spectroscope, Spectroscopically (spectrum and Gr. skopsem, to see)
(p. 10).

Spectrum (L. spectre, to see) (p. 9). '

Spermatozoon (Gr. sperma, seed; zoon, animal), the male sex-cell

(p. 71).
Sperm-cell (Gr. sperma, seed), the male sex-cell (p. 71).
Stamen (L. stare, to stand), the male organs of the flower.
Static (L. stare, to stand), pertaining to bodies at rest.
Stereotropism (Gr. stereos, solid; tropos, a turn), the turning toward

a solid (p. 229).

Stigma (Gr. stizein. to mark), the top of the female organ of a flower.

Style (L. stilus, anything long), the middle portion of the pistil,
leading from the stigma to the ovary.

Suture (L. su^re. to sew), the connections between the various bones
of the skull.

Symbiosis (Gr. syn, together; hios, life) (p. 154)-

Syndasmian (Gr! syn, together; desmein, to bind) (p. 275).

Synthesis, Synthetic (Gr. syn, together; thesis, a placing), the com-
bination of separate elements into a whole.

Tarsal (Gr. tarsos, the flat part of the foot), relating to the tarsus—

i.e., the ankle. , x r • * 1 •

Taxonomic (Gr. tassein, to arrange; nomos, rule), referring to classi-
fication.
Teleological (Gr. telos, issue ; logos, 2l discourse), referring to teleology,
the doctrine of the final issue of things.

336 THE FIRST PRINCIPLES OF EVOLUTION

Tibial (L. tibia, shinbone), relating to the shinbone.

Tort (L. tortus, twisted), a wrongful act (legal term).

Totemism (Algonquin, kitotem, the family-mark) (p. 293).

Triad (Gr. trias, union of three).

Triassic (Gr. trias, union of three), from the threefold grouping of this

geological system,
Trimorphoos (Gr. treis, three; morphe, form), with three distinct

forms.
Tropism (Gr. tropos, a turn) (p. 228).

Ungulates (L. ungula, a hoof), hoofed animals.

Uniformitariail (L. unus, one; forma, form) (p. 18).

Urea (Gr. ouron, urine), a substance produced by the decomposition

of proteid matter of the body, and carried ofE by the urine.
Usnfrnct (L. usus, use; fructus, fruit), the use and profit, but not the

property, of a thing.

Ventral (L. venter, the belly) , relating to the side of the belly.

Vermiform appendix (L. vermis, worm; forma, form; appendix, some-
thing appended) (p. 64).

Vertebrata, vertebral (L. vertebra, a bone of the spine), backboned
animals.

Vestigial (L. vestigare, to track), pertaining to vestiges — i.e., remains.

Villeinage (L. villanus, from villa, a village), the tenure of land by
villein — i.e., menial services.

Vitalism, Vitalist (L. vita, life), belief in a special vital principle of
life (p. 219).

Voluntarism (L, voluntas, will) (p. 220).

Volvocinese (L. volvere, to roll), an order of fresh- water algae.

Vttlcanism (L. Vulcan, the god of fire) (p. 18).

INDEX

Abiogenesis, 43, 107
Acquired characters, inheri-
tance of, 156, 175, 177, 178,
217, 218, 238, 303. See also
Modification and Use-inheri-
tance
Action system, 231
Adaptation, 88, 122, 124, 125

active, 177

between flowers and in-
sects, 129

colour-, 135

functional, 177

intellectual, 243

ontogenetic, 183

passive, 176, 177, 188

of plants, 131

predetermined, 99

self-, of flowers, 115
^Esthetic standard, 169, 170
Esthetics, 246
Agassiz, 86
Alcoholism, 301
Altar, 291
Amixia, 199
Anaximander, 107
Ancestor-worship, 293
Animals :

air-breathing, 25

arctic, 135

balance between, 312

cave-, 62

colouration of eggs, 133

compound, 307

desert-, 132

domestication, 281

Animals:

emotions, 254
frequenting trees, 133
fresh-water, 100
gregarious, 252
herbivorous, 1 25
higher, 113, 116, 143.
150, 228, 237, 244,

148,
251.

309. See also Quadru-
peds
imitating objects, 137
lower, 113, 116, 164, 227,

237. 242, 251, 307
marine, 100
marking, 135
multicellular, 73
nocturnal, 132
one-celled, 75, 228, 230.

See also Protozoa
terrestrial, 100
unsociable, 252
Animism, 289, 293, 296, 297.

See also Spirits
Ape-man, 28, 261, 267
Apogamy, 200
Archaean era, 24
Archaesthetism, 217
Archebiosis, 46
Architecture, 309
Aristotle, 43. 83, 107
Assimilation, 241
Atavism, 79
Atom, 30, 31, 40, 43
Atomic theory, 30, 107
Atrophy, 61, 113. i95- See also
Rudimentation

337 43

338 THE FIRST PRINCIPLES OF EVOLUTION

Avebury, Lord, 79. See also

Lubbock
Avoiding reaction, 231

Bachofen, J. J., 274, 277
Baer, Von, 86
Baldwin. J. M., 183
Barbarism, 271
Bates, 148
Bateson, W., 208
Bathmism, 217
Bax, Belfort. 298
Becquerel, Henri, 34
Beddard. F. E., 132, i34. I47
Bell, 146

Bergson, Henri. 221, 222. 235,
239, 240, 298. 315. 316, 317.

318

Biogenesis, 43

Biogenetic law, 69, 74

Biometricians, 213

Birds, 27, 10 1, 115
aquatic, 114
bell-, 167

colour of eggs, 133
cries, 245
instincts, 156

maternal, 240
parental, 250
intelligence, 241
marking, 79, 133. Hi
monogamous union, 278
paradise, 166

seasonal colour-change, 1 3 5
sex difierences, 165
sexual selection, 167. 169

song. 158. 170

swimming, 123

tail, 96, 98

wings, 52, 54, 61
Blackwell, 153
Blastula, 73
Blood-communion, 294

-corpuscles, 195

-feud, 283
Bohn, G., 231
Breeding, segregate, 200

separate, 200

Bronze-age, 29. See also Metal-
age
Buckman, S. S., 246
Bufion, 108

Butterflies, 52, 56. 79, 128, 133.
136

climatic variation, 116

geotropism, 230

inedible, 146, 147

Kallima, 138

leaf-, 187

mimicry, 148, 152. 164

seasonal dimorphism, 135

warning colouration, 146

Cambrian era, 24. 27
CandoUe, De. 87
Capitalism, 303. See also In-
dustrialism
Carboniferous age, 25. 26
Carr, C. Wildon, 318
Catastrophism, 118
Catchpool, 201
Cave -age, 265
Cell colony, 75
Cesnola, 179
"Chamberlin, Th. C, 14. 16. 22
Change, philosophy of, 316, 318
progressive, 50. See also
Evolution

Chellian age, 265

Chemotaxis, 169

Chemotropism, 228, 230

Citizenship, 284. 287

City state, 283, 285

Civilization, 271

Classification, 83, 87

Clodd, E.. 289

Co-adaptation, 187

Coccygeal bones, 64

Coelom, 73

Ccelomula, 75

Collective responsibility, 288

Colour, 131

distinctions, trivial, 181
resemblance, variable, 135

Colouration, 131
I alluring, 141

INDEX

339

Colouration, protective, 132,

133. 134. 170

warning, 143. I47
Communism, primitive, 280
Conduct, 252

human, 256
Constable, F. C, 159
Co-operation, 251, 280, 288, 303.

313
Cope, E. D., 115, 116, 214, 215.

217, 218
Copernicus, 7
Corpuscles, 35, 41. 42, 43- See

also Electron, negative
Correlation, 183, 184, 188, 198
Crawley, E., 296, 297. 298
Creation of matter, 7

theory, 17, 50. 58, 61
" Creative Evolution," 221, 315,

316
Cretaceous epoch, 27
CroU, James, 28
Crookes, Sir William, 34. 35
Cross-sterility, 199. 201. See

also Infertility
Cunningham, Professor J. T.,

133
Curie, Monsieur and Madame, 34

Custom, 254, 282

Cuvier, 86, 109

Dalton, John, 30

Danger-signals, 143

Darwin, Charles, on —
atrophy, 61
continuous variations, 207,

210
cross-fertilization, 128
geographical distribution,

100, loi, 102. 104
geological time, 29
heterostylism, 130, 131
human characteristics, 158,

249, 267
infertility, 203
instinct, 153. i54, 238
inter-relation of species, 123

Lamarckian factors, 180

Darwin, Charles, on —
laws of growth, 183
lunar function of woman, 47
monogamy, 278
moral faculty, 254, 257, 300
natural selection, 172, 178,

182, 190
origin of man, 157
plant-adaptations, 125, 126,

127
serial homologies, 56
sexual selection, 164, 168,

171
social instinct, 251
struggle for life, 120
Darwin, Erasmus, 3, 109
Darwin, Francis, 234
Darwin, G. H., 11, 16, 19. 30
Darwinism, 3, 49. 106, 117. 122.
124, 131, 172, 178, 184, 189,
190, 227. See also Neo-Dar-
winism
Dawkins, W. Boyd, 265
Death, 312, 313

Degeneration, i59. ^^i, 185,
192, 194. See also Atrophy
and Rudimentation
Delbceuf, J., 189
Democritus, 107
" Descent of Man," 63, i57. 249
Determinants, 195
Development, parallel, 218

progressive, 50, 56, 90, 107,

157
social, 307
See also Evolution
Devonian system, 25
DifEerential sensibility, 231
Differentiation, progressive, 309
Dissipation, 306, 307- See also

Dissolution
Dissociation of elements, 32, 33,

34, 37 - ,

Dissolution, 305, 3i3- See also

Dissipation
Dobereiner, 31
Dominants (of Mendel), 189
I (of Reinke). 220

340 THE FIRST PRINCIPLES OF EVOLUTION

Driesch, Hans, 44, 220
Dubois, Dr. Eugdne, 261
Duration, 316, 318

Ear. 68

Earth, 13, 17, 19, 20, 22, 313

Ectoderm, 73

Egg-cell, 71

Eimer, G. H. Th., 134, 192, 214.

215, 224
Eisig, Dr., 147
Electron, 35. 40, 42

negative, 36, 41, 42. See

also Corpuscle
positive, 41, 42
Elements. 33, 40, 314
Emanation, 37, 38
Embryogeny (embryonic de-
velopment), 69, 71, "J "J, 98,
194, 197, 250, 307
Embryology, 69
Empedocles, 107
Entelechy, 220
Entoderm. 73

Environmental conditions, 112,
114, 115. See also Lamarck-
ism
Eocene period, 27
Eolithic age, 261
Epicurus, 107
Equilibrium, 311, 312

radio-active, 38
Ethics, 4, 246, 247, 248, 256.

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