^^l^BSH^
©I|? i. 2^- l|tU ICihrarg
Jfortlj (Carolina &tatf ffinllege
QH366
W3Z
y LIBRARIES
S00588729 $
THIS BOOK IS DUE ON THE DATE
INDICATED BELOW AND IS SUB-
JECT TO AN OVERDUE FINE AS
POSTED AT THE CIRCULATION
DESK.
Wp
m \
mm
9
Wl
f99fi
APR 2 (^98
^
100M/7-89— 891646
THE WORLD OF LIFE
THE WORLD OF LIFE
A MANIFESTATION OF
CREATIVE POWER, DIRECTIVE MIND
AND ULTIMATE PURPOSE
BY
ALFRED RUSSEL WALLACE
O.M., F.R.S., D.C.L., Etc.
NEW YORK
MOFFAT, YARD & COMPANY
I 9 I I
Copyright, 1910, 191 1, by
Moffat, Yard and Company
New York
All Rights Reserved
Published January, 191 1
PEEFACE
In the present volume I have attempted to summarise and
complete my half-century of thought and work on the Dar-
winian theory of evolution. In several directions, I have
extended the scope and application of the theory, and have
shown that it is capable of explaining many of the phenomena
of living things hitherto thought to be beyond its range.
Among these are the detailed distribution of plants and
animals, which I have discussed at some length. It occupies
about one-fourth of the volume (Chapters II. to VI.)? and
brings out certain facts and conclusions which I believe mil
be of interest to all plant-lovers, and also be not without a
certain value to botanists.
'Next in importance are three chapters (X., XL, and XII.)
devoted to a general review of the Geological Eecord and a
discussion of the various problems arising out of it. Some
of the conclusions to which this examination leads us are, I
believe, both important and of much general interest.
In Chapter VIII. I have endeavoured to show natural selec-
tion actually at work in the continually perfecting that won-
derful co-adaptation of the most diverse forms of life which
pervades all nature. Some little-known aspects of bird-migra-
tion are here discussed, and proof is given of the enormous
importance of mosquitoes for the very existence of considerable
proportion of our birds, including most of our most favoured
pets and songsters. This chapter will, I think, have a special
interest for every bird-lover.
106920
yi THE WOKLD OF LIFE
In Chapter IX. I deal with some little-known phenomena
in that hitherto neglected field of enquiry which I have termed
" Eecognition Marks." Besides the obvious uses implied by
their name, I have shown that they are of great importance —
perhaps absolutely essential — in the process of the evolution
of new species. During the enquiry I have arrived at the
somewhat startling conclusion that the exquisite variety and
beauty of insect-coloration and marking have not been devel-
oped through their ovni visual perceptions, but mainly — per-
haps even exclusively — through those of higher animals. I
show that brilliant butterflies do not, and almost certainly
cannot, recognise each other by colour, and that they probably
do not even perceive colour at all except as to a certain extent
presenting visual differences.
But besides the discussion of these and several other allied
subjects, the most prominent feature of my book is that I enter
into popular yet critical examination of those underlying funda-
mental problems which Darwin purposely excluded from his
"works as being beyond the scope of his enquiry. Such are the
nature and causes of Life itself, and more especially of its
most fundamental and mysterious powers — growi:h and repro-
duction.
I first endeavour to show (in Chapter XIV.) by a careful
consideration of the structure of the bird's feather ; of the
marvellous transformations of the higher insects ; and, more
especially of the highly elaborated wing-scales of the Lepidop-
tera (as easily accessible examples of what is going on in every
part of the structure of every living thing), the absolute neces-
sity for an organising and directive Life-Principle in order to
account for the very possibility of these complex out-growths.
PEEFACE
Vll
I argue that they necessarily imply first, a Creative Power,
which so constituted matter as to render these marvels pos-
sible; next, a directive Mind, which is demanded at every step
of the process we term growth and often look upon as so
simple and natural a process as to require no explanation;
and, lastly, an ultimate Purpose, in the very existence of the
whole vast life-world in all its long course of evolution through-
out the eons of geological time. This Purpose, which alone
throws light on many of the mysteries of its mode of evolu-
tion, I hold to be the development of Man, the one crowning
product of the whole cosmic process of life-development; the
only being which can to some extent comprehend nature ; which
can perceive and trace out her modes of action ; which can
appreciate the hidden forces and motions everywhere at w^ork,
and can deduce from them all a supreme and overruling mind
as their necessary cause.
If we accept some such view as I have now indicated, I
show (in Chapters XV. and XVI.) how strongly it is sup-
ported and enforced by a long series of facts and co-relations
which we can hardly look upon as all purely accidental coin-
cidences. Such are the infinitely varied products of living
things which serve man's purposes and man's alone — not only
by supplying his material wants, and by gratifying his higher
tastes and emotions, but as rendering possible many of those
advances in the arts and in science which we claim to be the
highest proofs of his superiority to the brutes and of his
advancing civilisation.
From a consideration of these better-knoAvn facts I proceed
(in Chapter XXII.) to an exposition of the mystery of cell-
growth; to a consideration of the elements in their special
relation to the earth itself and to the life-world ; while in the
viii THE WORLD OE LIFE
last chapter I endeavour to show the purpose of that law of
diversity which seems to pervade the whole material Universe.
As an '' excursus," I devote Chapter XIX. to a discussion of
the nature, extent, and uses of Pain, as strictly deduced from
the law of Evolution. Strangely enough, this has never, I
believe, been done before ; and it enables us to answer the
question — ^' Is Xature Cruel ? " with a decided negative.
This outline of the varied contents and objects of my book,
wdll, I hope, be useful to my readers, and especially to my
reviewers, by directing their attention to those parts of the
work in which they may be more especially interested.
I also wish to point out that, however strange and heretical
some of my beliefs and suggestions may appear to be, I claim
that they have only been arrived at by a careful study of the
facts and conditions of the problem. I mention this because
numerous critics of my former work — Man's Place in the
Universe (to which this may be considered supplementary) — ■
treated the conclusions there arrived at as if they were wholly
matters of opinion or imagination, and founded (as were their
own) on personal likes or dislikes, without any appeal to evi-
dence or to reasoning.
I have now only to express my thanks to the friends and
strangers who have kindly assisted me with numerical and
other data for various portions of my work ; as well as to those
publishers and authors who have allowed me to use the en-
gravings or photographs with which my book is illustrated.
They are in, every case (I believe) acknowledged in the text,
or on the various plates and figures.
Broadstone, Wimborne,
November 1910.
CONTENTS
CHAPTER I
PAGE
What is Life and Whence it Comes 1
CHAPTER II
Species — their Numbers, Variety, and Distribution ... 12
CHAPTER III
The Numerical Distribution of British Plants : Temperate
Floras Compared 24
CHAPTER IV
The Tropical Floras of the World • . . 43
CHAPTER V
The Distribution of Animals 89
CHAPTER VI
The Numerical Distribution of Species in Relation to Evolu-
tion 100
CHAPTER VII
Heredity, Variation, Increase 109
CHAPTER VIII
Illustrative Cases of Natural Selection and Adaptation . . 134
ix
X THE WORLD OF LIPE
CHAPTEE IX '
PAGE
The Importance of Eecognition-marks in Evolution . . .168
CHAPTEE X
The Earth's Surface-changes the Motive Power of Evolution 187
CHAPTEE XI
The Progressive Development of the Life-World as shown
by the Geological Eecord 303
CHAPTEE XII
Life of the Tertiary Period 235
CHAPTEE XIII
Some Extensions of Darwin's Theory ....... 371
CHAPTEE XIY
Birds and Insects as Proofs of an Organising and Directive
Life-principle 309
CHAPTEE XV
General Adaptation of Plants, Animals, and Man . . . .321)
CHAPTEE XVI
The Vegetable Kingdom in its special Eelation to Man . . 350
CHAPTEE XVII
The Mystery of the Cell 361
CONTENTS xi
CHAPTER XVIII
PAGE
The Elements and Water in Eelation to the Life-AYorld . . 383
CHAPTER XIX
Is Nature Cruel? The Uses of Pain 398
CHAPTER XX
Infinite Variety the Law of the Universe 415
LIST OF ILLUSTRATIONS
FIG. PAGE
1. Forest in Kelantan, Malay Poninsula 48
2. Forest in Perak, Malay Peninsula 50
3. Campos of Lagoa Santa, Brazil GO
4. View of Campo Cerrado, Lagoa Santa 70
5. View at Lapa Vermelha Eocks, Lagoa Santa . . . 72
6. Casselia chamaedrifoUa 73
7. Andira laurifolia 74
8. A Forest Stream, West Java 80
9. Diagram of Curve of Stature IIG
10. Diagram of Variation 118
11. American Bison 124
12. The Lemming 129
13. Shooting Wild Cleese at the Arctic Circle .... 147
14. Geese Migrating 148
15. Mr. Seebohm's Mosquito Veil 149
16. Watching Grey Plover Among Mosquitoes .... 150
17. Ice Breaking up, Petchora Eiver 152
18. Midsummer on the Tundra 153
19. Sudden Arrival of Birds 154
20. Grey Plover, Xest and Young 156
21. The Higher Tundra 159
22. Migration Xight at Heligoland 162
23. Mimicry of Wasp by a Beetle 170
24. Tragelaphus speJcei 1<4
25. Boocercus euryceros 1<4
26. Gazella granii 1^4
27. Gazelli walleri l'^4
28. Strepsiceros Jciidu 1^"
29. Strepsiceros imherhis 1^6
30. Bubalis JacTcsonia 1'^^
31. ^pyceros melampus 1*^6
• • •
Xlll
xiv THE WORLD OF LIFE
riG.
PAGE
32. Cohus leche 178
33. Cohus defossa 178
34. Cohus Maria 178
35. Oryx Gazella 178
36. (E dicnertius grallarius 176
37. (Edicnemus magnirostris 176
38. Great Indian Stone Curlew 177
39. Thelodus scoticus 208
40. Pteraspis rostrata 208
41. Cephalaspis murchisoiii 209
42. Protocercal Tail 209
43. Heterocercal Tail 209
44. Homocercal Tail 210
45. Pariasaurus Bainii 214
46. Skull of Dicynodon lacerticeps 214
47. Slvull of JEIusaurus felinus 215
48. Skull of Inostransevia 216
49. Eestoration of Dimetrodon 216
50. Skeleton of Iguanodon 218
51. Eestoration of Iguanodon 218
52. Skull of Iguanodon 218
53. Skeleton of Armoured Dinosaur 218
54. Skull of Horned Dinosaur 219
55. Eestoration of Stegosaurus 220
56. Sauropodous Dinosaur 221
57. Skeleton of Diplodocus carnegii 222
58. Skull of Sauropodous Dinosaur 222
59. Skull of a Theropodous Dinosaur 222
60. Outline and Skeleton of Plesiosaurus macro cephalus . 224
61. Outline and Skeleton of Ichthyosaurus communis . . 224
62. Bones and Paddles of Ichthyosaurus 224
63. Skeleton of Pterodactylus spectahilis 225
64. Eestoration of Rhymphorhynchus phyllurus .... 226
65. Toothless Pterodactyl 226
66. Skull of Peteranodon longiceps 227
67. Lower Jaw of Phasolothcrium huchlandi 228
68. Jaw and Teeth of Spalacotherium. tricuspidens . • • 228
LIST OF ILLUSTRxVTIONS xv
FIG. . PAGE
69. Jaw of Triconodon mordax 228
70. Drawing of the Fossil Lizard-tailed Bird .... 230
71. Skull of Arcliccoptcryxsiemensi 231
72. Skeleton of Phenacodus primwvus 232
73. Skeleton of Uintatherium ingens 236
74. Skull of Uintatherium cornutum 237
75. Skeleton of Titanotherium rohustum 238
76. Skull of Arsinoitheriiim zitteli 240
77. Skeleton of a Creodont 242
78. Skeleton of Hyopotamus brachyrhynchus 243
79. Anoplotherium commune 244
80. Palwotheriiim magnum 244
81. Skull of Moeriilierium hjonsi 244
82. Skulls of Ancestral Elephants 246
83. Skeleton of Tetrahelodon angvstidens 246
84. Probable Appearance of Tetrahelodon augustidens . . 246
85. Skeleton of Mastodon americanus 247
^Q. Skeleton of Mammoth Elephas promigenius .... 249
87. Skeleton of Toxodon platensis 250
S8. Skeleton of Glyptodon clavipeR 253
89. Probable Appearance of tlio Giant Ground-sloth . . 254
90. Mylodon rohustus 254
91. Skeleton of Scelidotlierium leptocephalum .... 255
92. Skull of an Extinct Marsupial 257
93. Skull of Thylacoleo carnifex 258
94. Sabre-toothed Tiger 284
95. Skeleton of Giant Deer 284
96. Conocoryphe sultzeri .» 287
97. Paradonides hohemiciis . ♦ 287
98. Acidaspis dufrenoyi 288
99. Ceratites nodosus 289
100. Trachyceras aon 28 J
101. Crioceras emerici 289
102. Heieroceras emerici 289
103. Macroscaphites ivanii . . o 290
104. Hamites rotundus -^"^^
105. Ptychoceras emericiciniim '^•^^
xvi THE WORLD OF LIFE
PAGE
106. Ancyloceroe matheronianiinis 390
107. Head of Babirusa 296
108. Perspective View of a Part of a Wing-feather . . .313
109. Oblique Section Showing how the Barbules hook To-
gether 312
110. Diagram of Nuclear Division 3 TO
THE WORLD OF LIFE
CHAPTER I
WHAT LIFE IS, AjI^D WHENCE IT COMES
When primeval man first rose above the brutes from which
he was developed ; when, by means of his superior intellect,
he had acquired speech and the use of fire ; and more espe-
cially when his reasoning and reflecting faculties caused him
to ask those questions which every child now asks about the
world around it — what is this ? and why is that ? — he would,
for the first time, perceive and wonder at the great contrast
between the living and the not-living things around him.
He would first observe that the animals which he caught
and killed for food, though so unlike himself outwardly, were
yet very like his fellow-men in their internal structure. He
would see that their bony framework was almost identical in
shape and in substance with his own; that they possessed flesh
and blood, that they had eyes, nose, and ears; that presumably
they had senses like his own, sensations like his own ; that they
lived by food and drink as he did, and yet were in many ways
so different. Above all, he would soon notice how inferior
they were to himself in intellect, inasmuch as they never made
fires, never used any kind of tools or weapons ; and that,
although many of them were much stronger than he was, yet
his superiority in these things, and in making traps or pitfalls
to capture them, showed that he was really their superior and
their master.
Gradually, probably very slowly, he would extend these
observations to all the lower forms of life, even wdjen both
1
2 THE WORLD OF LIFE
externally and internally he could find no resemblance what-
ever to his own body; to crabs and winged insects, to land-
shells and sea-shells, and ultimately to everything which by
moving and feeding, by growdng and dying, showed that it
was, like himself, alive. Here, probably, he would rest for
awhile, and it might require several generations of incipient
philosophers to extend the great generalisation of " life " to
that omnipresent clothing of the earth's surface produced by
the infinitely varied forms of vegetation. The more familiar
any phenomenon is — the more it is absolutely essential to
our life and well-being — the less attention we pay to it and
the less it seems to need any special explanation. Trees, shrubs,
and herbs, being outgrowths from the soil, being incapable of
any bodily motion and usually exhibiting no indications of
sensation, might w^ell have been looked upon as a necessary
appendage of the earth, analogous to the hair of mammals or
the feathers of birds. It was probably long before their end-
less diversity attracted much notice, except in so far as the
fruits or the roots were eatable, or the stems or foliage or bark
useful for huts or clothing ; wdiile the idea that there is in them
any essential feature connecting them wdth animals and en-
titling them to be classed all together as members of the great
^vorld of life would only arise at a considerably later stage
of development.
It is, in fact, only in recent times that the very close resem-
blance of plants and animals has been generally recognised.
The basis of the structure of both is the almost indistinguish-
able cell ; both grow from germs ; both have a varied life-period
from a few" months to a maximum of a few" hundreds of vears :
both in all their more highly organised forms, and in many of
their lower types also, are bisexual ; both consist of an immense
variety of distinct species, which can be classified in the same
way into higher and higher groups; the laws of variation,
heredity, and the struggle for existence apply equally to both,
and their evolution under these laws has gone on in a parallel
course from the earliest periods of the geological record.
WHAT LIFE IS 3
The differences between plants and animals are, however,
equally prominent and fundamental. The former are, with
few exceptions, permanently attached to the soil ; they absorb
nourishment in the liquid or gaseous state only, and their tissues
are almost wholly built up from inorganic matter, while they
give no clear indications of the possession of sensation or vol-
untary motion. But notwithstanding these marked differences,
both animals and plants are at once distinguished from all the
other forms of matter that constitute the earth on which they
live, by the crowning fact that they are alive; that they grow
from minute germs into highly organised structures; that the
functions of their several organs are definite and highly varied,
and such as no dead matter does or can perform ; that they are
in a state of constant internal flux, assimilating new material
and throwing off that which has been used or is hurtful, so as
to preserve an identity of form and structure amid constant
change. This continuous rebuilding of an ever-changing highly
complex structure, so as to preserve identity of type and at
the same time a continuous individuality of each of many
myriads of examples of that type, is a characteristic found
nowhere in the inorganic world.
So marvellous and so varied are the phenomena presented
by living things, so completely do their powers transcend those
of all other forms of matter subjected to mechanical, physical,
or chemical laws, that biologists have vainly endeavoured to
find out what is at the bottom of their strange manifestations,
and to give precise definitions, in terms of physical science, of
what "life'' really is. One authority (in Chambers's Ency-
clopaedia) summed it up in three w^ords — "Continuity,
Ehythm, and Freedom," — true, perhaps, but not explanatory ;
while Herbert Spencer declared it to be — " the definite com-
bination of heterogeneous changes, both simultaneous and suc-
cessive, in correspondence with external co-existences and
sequences." This is so technical and abstract as to be unin-
telligible to ordinary readers.
The following attempt at a tolerably complete definition
4 THE WORLD OF LIFE
appears to sum up the main distinctive characters of living
things : —
Life is that 'power which, primarily from air and water and
the substances dissolved therein, builds up organised and highly
complex structures possessing definite forms and functions:
these are preserved m a continuous state of decay and repair by
internal circulation of fluids and gases; they reproduce their
like, go through various phases of youth, maturity, and age,
die, and quickly decompose into their constituent elements.
They thus form continuous series of similar individuals; and,
so long as external conditions render their existence possible,
seem to possess a potential immortality.
The characteristics here enumerated are those which apply
to both plants and animals, and to no other forms of matter
whatever. It is often stated that crystals exhibit the essential
features of some of the lowest plants ; but it is evident that,
with the exception of the one item of " definite form/^ they
in no way resemble living organisms. There is no doubt, how-
ever, that crystals do exhibit definite forms, built up by the
atoms or molecules of various elements or compounds under
special conditions. But this takes us a very small way towards
the complex structure and organisation of living things.
There are still people who vaguely believe that ^^ stones
grow," or that '^ all matter is really alive," or that, in their
lowest and simplest forms, the organic and the inorganic are
indistinguishable. For these ideas, however, there is not a
particle of scientific justification. But the belief that '^ life "
is a product of matter acted upon by chemical, electrical, or
other physical forces, is very widely accepted by men of science
at the present day, perhaps by a majority. It is, in fact, held
to be the only scientific view, under the name of ^' monism " ;
while the belief that ^^ life " is sui generis, that it is due to
other laws than those which act upon dead or unorganised
matter, that it affords evidence of an indwelling power and
guidance of a special nature, is held to be unscientific — to
be, in fact, an indication of something akin to, if not actually
WHAT LIFE IS 5
constituting, an old-fashioned superstition. That such a view
is not uncommon may be shown by a few extracts from scien-
tific writers of some eminence.
The well-known German biologist Ernst Haeckel, in a recent
work, makes the following statement :
" The peculiar phenomenon of consciousness is not, as Du Bois-
Eeymond and the dualistic school would have us believe, a com-
pletely transcendental problem ; it is, as I showed thirty-three years
ago, a physiological problem, and, as such, must be reduced to the
phenomena of physics and chemistry " (The Eiddle of the Uni-
verse, p. 65, translated by Joseph M'Cabe).
Again he says :
" The two fundamental forms of substance, ponderable matter
and ether, are not dead, and only moved by extrinsic force, but they
are endowed with sensation and will (although, naturally, of the
lowest grade) ; they experience an inclination for condensation, a
dislike of strain; they strive after the one and struggle against the
other'' (p. 78).
In these two passages we have a self-contradiction in mean-
ing if not in actual words. In the first, he reduces conscious-
ness to phenomena of physics and chemistry ; in the second
he declares that both matter and ether possess sensation and
will. But in another passage he says he conceives ^^ the ele-
mentary psychic qualities of sensation and will which may be
attributed to atoms to be unconscious" (p. 64).
It is this quite unintelligible theory of matter and ether
possessing sensation and will, being able to strive and struggle
and yet be unconscious, which enables him to say:
"We hold with Goethe that matter cannot exist and be oper-
ative without spirit, nor spirit without matter. We adhere firmly
to the pure, unequivocal monism of Spinoza : Matter, or infinitely
extended substance, and Spirit (or Energy), or sensitive and think-
ing substance, are the two fundamental attributes, or principal
properties, of the all-embracing essence of the world, the universal
substance" (p. 8).
6 THE WOELD OF LIFE
Here we have yet another contradiction — that the tJiinking
infinite substance is unconscious! This leads to his theory
of the " cell-soul/' which is the origin of all consciousness, hut
which is itself unconscious. This he reiterates emphatically.
He tells us that at a certain grade of organisation '^ conscious-
ness has been gradually evolved from the psychic reflex activity,
and now conscious voluntary action appears" (p. 41). Along
wdth these strange conceptions, "vvhich really explain nothing,
he propounds his " Law of Substance " as the one great foun-
dation of the universe. This is merely another name for
" persistence of force " or ^' conservation of energ}^," yet at
the end of the chapter expounding it he claims that, '' in a
negative way, it rules out the three central dogmas of meta-
physics— God, freedom, and immortality" (p. 83). A little
further on he again states his position thus:
" The development of the universe is a monistic mechanical
process, in which we discover no aim or purpose whatever; what
we call design in the organic world is a special result of biological
agencies; neither in the evolution of the heavenly bodies, nor in
that of the crust of the earth do we find any trace of a controlling
purpose — all is the result of chance.^'
Then, after discussing what is meant by chance, he con-
cludes :
" That, however, does not prevent us from recognising in each
' chance ' event, as we do in the evolution of the entire cosmos, the
universal sovereignty of nature's supreme law, the taw of sub'
stance'* (p. 97).
Again, he defines his position still more frankly:
*' Atheism affirms that there are no gods or goddesses, assuming
that god means a personal, extra-mundane entity. This ^ godless
world-system ' substantially agrees with the monism or pantheism
of the modern scientist. It is only another expression for it, em-
phasising its negative aspect, the non-existence of any supernatural
deity" (p. 103).
WHAT LIFE IS 7
These vague and often incomprehensible assertions are inter-
spersed with others equally unprovable, and often worded so
as to be very offensive to religious minds. After having put
forth a host of assertions as to a possible future state, which
exhibit a deplorable ignorance of the views of many advanced
thinkers in all the Churches, he says:
" Our own ^ human nature ' which exalted itself into an image
of God in an anthropistic illusion, sinks to the level of a placental
mammal, which has no more value for the universe at large than
the ant, the fly of a summer's day, the microscopic infusorium, or
the smallest bacillus. Humanity is but a transitory phase of the
evolution of an eternal substance, a particular phenomenal form of
matter and energy, the true proportion of which we soon perceive
when we set it on the background of infinite space and eternal
time" (p. 87).
The writings of Haeckel, the extremely dogmatic and asser-
tive character of which have been illustrated in the preceding
quotations, have had an immense influence on many classes of
readers, who, when a man becomes widely known as a great
authority in any department of science, accept him as a safe
guide in any other departments on which he expresses his
opinions. But the fact is that he has gone altogether out of
his own department of biological knowledge, and even beyond
the whole range of physical science, when he attempts to deal
with problems involving '' infinity " and ^' eternity." He de-
clares that " matter," or the material universe, is infinite, as
is the '' ether," and that together they fill infinite S2:)ace, and
that both are ^^ eternal " and both '' alive." ^one of these
things can possibly be hnown, yet he states them as positive
facts. The whole teaching of astronomy by the greatest
astronomers to-day is that the evidence now at our command
points to the conclusion that our material universe is finite,
and that we are rapidly approaching to a knowledge of its
extent. Our yearly increasing acquaintance with the possibil-
ities of nature leads us to the conclusion that in infinite space
8 THE WORLD OF LIFE
there lyiay be other universes besides ours; but if so, they may
l^ossibly be different from ours — not of matter and ether only.
To assert the contrary, as Ilaeckel does so confidently, is surely
not science, and very bad philosophy.
He further implies, and even expressly states, that there is
no spirit-world at all ; that if life exists in other worlds it must
be material, physical life; and that, as all worlds move in
cycles of development, maturity, and destruction, all life must
go through the same phases — that this has gone on from all
eternity past, and will go on for all eternity to come, with no
past and no future possible, but the continual rise of life up to
a certain limited grade, which life is always doomed to extinct
tion. And it is claimed that this eternal succession of futile
cycles of chance development and certain extinction is, as an
interpretation of nature, to be preferred to any others ; and
especially to those which recognise mind as superior to matter,
which see in the development of the human intellect the prom-
ise of a future life, and which have in our own day found a
large mass of evidence justifying that belief.
With Professor HaeckeFs dislike of the dogmas of theo-
logians, and their claims to absolute knowledge of the nature
and attributes of the inscrutable mind that is the power within
and behind and around nature, many of us have the greatest
sympathy ; but we have none with his unfounded dogmatism
of combined negation and omniscience, and more especially
when this assumption of superior knowledge seems to be put
forward to conceal his real ignorance of the nature of life
itself. He evades altogether any attempt to solve the various
difficult problems of nutrition, assimilation, and growth, some
of which, in the case of birds and insects, I shall endeavour
to set forth as clearly as possible in the present volume. As
Professor Weismann well puts it, the causes and mechanism
by which it comes about that the infinitely varied materials
of which organisms are built up ^' are always in the right
place, and develop into cells at the right time," are never
touched upon in the various theories of heredity that have been
WHAT LIFE IS 9
put forward, and least of all in that of Haeckel, who comes
before us with what he claims to be a solution of the Riddle
of the Universe.
Huxley on the Nature and Origin of Life
Although our greatest philosophical biologist, the late Pro-
fessor T. H. Huxley, opposed the theory of a '' vital force "
as strongly as Haeckel himself, I am inclined to think that
he did so because it is a mere verbal explanation instead of
being a fundamental one. It conceals our real ignorance un-
der a special term. In his Introduction to the Classification
of Animals (1869), in his account of the Rhizopoda (the
group including the Amoebse and Foraminifera), he says:
"Nor is there any group in the animal kingdom which more
admirably illustrates a very well-founded doctrine, and one which
was often advocated by John Hunter, that life is the cause and not
the consequence of organisation; for in these lowest forms of ani-
mal life there is absolutely nothing worthy of the name of organi-
sation to be discovered by the microscopist, though assisted by the
beautiful instruments that are now constructed. . . . It is
structureless and organless, and without definitely formed parts.
Yet it possesses all the essential properties and characters of vitality.
Nay, more, it can produce a shell; a structure, in many cases, of
extraordinary complexity and most singular beauty.
" That this particle of jelly is capable of guiding physical forces
in such a manner as to give rise to those exquisite and almost
mathematically-arranged structures — being itself structureless
and without permanent distinction or separation of parts — is
to my mind a fact of the profoundest significance'^ (p. 10).
This was written only a year after the celebrated lecture
on " The Physical Basis of Life," in which Huxley made
statements which seem opposed to those above quoted, and which
certainly appear to be less philosophical. For example, he
says that when carbon, hydrogen, oxygen, and nitrogen are
combined with some other elements, they produce carbonic acid,
water, and nitrogenous salts. These compounds are all life-
10 THE WORLD OF LIFE
less. " But wlien they are brought together under certain
conditions they give rise to the still more complex body, proto-
plasm, and this protoplasm exhibits the phenomena of life "
(p. 52). Then follows an exposition of the well-known argu-
ment as to water and crystals being produced by the " proper-
ties " of their constituent elements, with this conclusion :
" Is the case any way changed when carbonic acid, water, and
nitrogenous salts disappear, and in their place, under the influence
of pre-existing living protoplasm, an equivalent weight of the
matter of life makes its appearance?" (p. 53).
But here we have the words I have italicised introduced
which were not in the previous staj:ement; and these are of
fundamental importance considering the tremendous conclu-
sion he goes on to draw from them — " that the thoughts to
which I am now giving utterance are the exj)ression of molec-
ular changes in that matter of life which is the source of our
other vital phenomena." At the end of the lecture he says
that " it is of little moment whether we express the phenomena
of matter in terms of spirit, or the phenomena of spirit in
terms of matter — each statement has a certain relative truth."
But he thinks that in matters of science the materialistic ter-
minology is in every way to be preferred.
This is vague and unsatisfactory. It is not a mere question
of terminology ; but his statement that " thought is the expres-
sion of molecular change in protoplasm " is a mere begging
of the whole question, both because it is absolutely unproved,
and is also inconsistent with that later and clearer statement
that " life is the cause of organisation " ; but, if so, life must
be antecedent to organisation, and can only be conceived as
indissolubly connected with spirit and with thought, and with
the cause of the directive energy everyw^here manifested in the
growth of living things.
In the present volume I am endeavouring to arrive at a
juster conception of the mystery of the Life- World than that
of Professor Haeckel, and bv a verv different method. I shall
WHAT LIFE IS 11
endeavour to give a kind of bird's-eye sketch of the great life-
drama in many of its broader and less-known phases, showing
how they all form parts of the grand system of evolution,
through adaptation to continuous changes in the outer world.
I shall also endeavour to penetrate into some of the less trodden
paths of nature-study, in order to exhibit the many indications
that exist of the preparation of the Earth for Man from the
remotest eons of geological time.
CHAPTER II
SPECIES THEIK NUMBEKS, VAKIETY, AND DISTRIBUTION
When we begin to inquire into the main features, the mode
of development, the past history, and the probable origin of
the great World of Life of which we form a part, which
encloses us in its countless ramifications, and upon whose pres-
ence in ample quantity we depend for our daily food and
continued existence, we have perpetually to discuss and to deal
with those entities technically kno^vn as species, but which are
ordinarily referred to as soi'ts or kinds of plants and animals.
When we ask how many hinds of deer or of thiTishes, of trout
or of butterflies, inhabit Britain, w^e mean exactly the same
thing as the biologist means by species, though we may not be
able to define what we mean so precisely as he does.
Many people imagine, however, that Darwin's theory proves
that there are no such things as species ; but this is a complete
misconception, though some biologists use language which
seems to support it. To myself, and I believe to most natural-
ists, species are quite as real and quite as important as when
they were held to be special creations. They are even more
important, because they constitute the only definite, easily rec-
ogTiised, and easily defined entities which form the starting-
point in all rational study of the vast complex of living things.
They are now known to be not fixed and immutable as for-
merly supposed; yet the great mass of them are stable within
very narrow limits, w^hile their changes of form are so slow,
that it is only now, after fifty years of continuous search by
countless acute observers, that we have been able to discover
a very few cases in which a real change — the actual produc-
tion of new species — appears to be going on before our eyes.
The reader may therefore rest assured that there is no mystery
1^
DISTRIBUTIO'N^ OF SPECIES 13
in the word species, but that he may take it as meaning the
same as kind, in regard to animals and plants in a state of
nature, and that he will have no difficulty in following the
various discussions and expositions in which this term is nec-
essarily so prominent. The reason why species is the better
term is because hind is used in two distinct senses — that of
species when we speak of kinds of deer, of squirrels, or of
thrushes, but also that of a genus or a family when we
speak of the deer, squirrel, or thrush kind, as meaning the
whole group of these animals. If we used the word tribe
instead of hind in this latter sense, all ambiguity would be
avoided.
Eew persons who have not studied some branch of natural
history have any idea of the vast extent, the infinite variety,
the omnipresence and the intermingling of the varied species
of animals and plants, and still less of their wonderful co-adap-
tation and interdependence. It is these very characteristics
that are least dwelt upon in books on natural history, and they
are largely overlooked even in works on evolution. Yet they
form the very basis of the phenomena to be explained, and
furnish examples of development through survival of the fittest,
on a larger scale and often of easier comprehension than the
special cases most frequently adduced. It is this ground-work
of the whole subject that we will now proceed to consider.
The Distribution of Local and ^yorld Species
The first important group of facts which we have to con-
sider is that which relates to the number of existing species
of the tw^o great divisions of life, plants and animals, and their
mode of distribution over the earth's surface.
Every one who begins to study and collect any gToup of
animals or plants is at once struck by the fact that certain
fields, or woods, or hills are inhabited by species which he can
find nowhere else ; and further, that, whereas some kinds are
very common and are to be found almost everywliere, others
are scarce and only occur in small numbers even in the places
14 THE WORLD OF LIFE
where alone they are usually to be found. These peculiarities
are most strongly marked in the case of plants, and in a less
degree among insects and land-shells; and in the former group
they are easily seen to depend mainly on such obvious peculiari-
ties as soil and moisture, exposure to sun or wind, the pres-
ence or absence of woods, streams, or mountains.
But besides these inorganic causes — soil, climate, aspect,
etc. — which seem primarily to determine the distribution of
plants, and, through them, of many animals, there are other
and often more powerful causes in the organic environment
which acts in a variety of ways. Thus, it has been noticed
that over fields or heaths where cattle and horses have free
access seedling trees and shrubs are so constantly eaten down
that none ever grow to maturity, even although there may be
plenty of trees and woods around. But if a portion of this
very same land is enclosed and all herbivorous quadrupeds
excluded, it very quickly becomes covered with a dense vege-
tation of trees and shrubs. Again, it has been noticed that
on turfy banks constantly cropped by sheep a very large variety
of dwarf plants are to be found. But if these animals are
kept out and the vegetation allowed to grow* freely, many of
the dwarfer and more delicate plants disappear owing to the
rapid growth of grasses, sedges, or shrubby plants, which, by
keeping off the sun and air and exhausting the soil, prevent
the former kinds from producing seed, so that in a few years
they die out and the vegetation becomes more uniform.
A modified form of the same general law is seen when any
ground is cleared of all vegetation, perhaps cultivated for a
year or two, and then left fallow. A large crop of weeds
then grows up (the seeds of which, must have beeoi brought
by the wind or by birds, or have lain dormant in the ground) ;
but in the second and third years these change their propor-
tions, some disappear, while a few new ones arrive, and this
change goes on till a stable form of vegetation is formed, often
very different from that of the surrounding country. Such
changes as these have been observed by local botanists on rail-
DISTRIBUTION OF SPECIES 15
way banks, of which I have given several examples in my
Island Life (p. 513, footnote). All these phenomena, and
many others which will be referred to later, are manifestly
due to that " struggle for existence " which is one of the great
factors of evolution through " survival of the fittest."
A Lincolnshire clergyman (Rev. E. Adrian Woodruff e-Pea-
cock of Cadney) has long studied the distribution of plants in
a very minute and interesting manner, more especially in his
own parish, but very extensively over the whole county. His
more exact method is to divide up a field into squares of about
16 feet each way with pegs, and then to note on special forms
or note-books (1) a list of the species found in each square,
and (2) the frequency (or proportion) of the occurrence of
each species. From these the frequency over the whole field
can be estimated, and the botanical peculiarities of various
fields very accurately determined. By comparing the detailed
flora of each field with its surface-geology, aspect, altitude,
degree of moisture or aridity, etc., a very accurate conclusion
as to the likes and dislikes of particular plants may be arrived
at.
As an example of the detailed treatment of a rather uncom-
mon yet widely distributed plant, he has sent me a copy of his
paper on the Black Horehound (Ballota nigra), sl species not
uncommon over much of Central Europe, but scattered over
Central and Southern Britain only in a few favourable locali-
ties. In Lincolnshire it is found all over the county in suitable
spots, but prefers a warm, open, and limy soil, as shown by
150 records giving notes of its occurrence. The general results
of the inquiry are thus given:
"AVhen the sheets of notes are analysed the following points
come out. It is a hedge and ditch-side species, but it seems to
prefer a bank to the flat in the proportion of 10 to 1 ; the sunny
bank to the shady side of a road running east and west in nearly
the same proportion. On sandy soils it seems to get away from
the villages to a greater distance than on clays, but perhaps the
rabbit may explain this. It extends from Cadney village along
16 THE WORLD OF LIFE
hedge and ditch banks on roadsides as far as the Sandy Glacial
Gravel extends in any direction. It is found in bushy ground,
in old quarries and gravel pits, and on the decaying mud-capping
of limestone walls. It is exterminated by stock in pasture, unless
it is protected by the stinging-nettle or by the fouling of the
ground by rabbits. It is apparently never found in meadows. It
is even sometimes eaten by cows, when the much-loved Lamium
album (the white dead-nettle) is left untouched; but it would
seeem to be taken as a corrective or relish rather than as food.
It is found so rarely in the open that it would almost appear
to be a shade species of bushy ground.
*' To sum up, Ballota nigra can only survive (in Lincolnshire)
when unconsciously protected by man; for its natural require-
ments, a bushy, open, limy, lightly stocked soil is practically not
to be found.^'
This careful study of a single species of plant gives us an
excellent picture of the struggle for existence on the outer
limit of the range of a species, where it first becomes rare,
and, when the conditions become a little less favourable, ceases
to exist. How this struggle affects the flora of limited areas
under slightly different conditions is shown by the same
writer's comparison of meadow and pasture.
Tw^o fields of each were chosen in the same parish and with
the same subsoil (Sandy Glacial Gravel) so as to afford fair
examples of each. With the one exception of the mode of
cultivation they were as alike as possible. Both had at some
remote period been ploughed, as shown by faint ridges, but
no one living or their immediate predecessors could remember
them in any different condition from the present one. The
four fields (29 acres together) contained in all 78 species of
plants ; but only 46 of these were found in both pasture and
meadow. The number of species in each was nearly the same
— 60 in the meadows, 64 in the pastures ; 14 species being
found only in the meadows and 18 in the pastures. Broadly
speaking, therefore, one-fifth of all the species growing on these
29 acres became restricted to well-defined portions of them
disteibutio:n^ of species 17
according as these portions were grazed by farm stock or reg-
ularly mown for hay.
Again, Mr. Woodruff e-Peacock states, that the assemblage
of plants that form pasture-lands not only varies with every
change of soil and climate, but also with any change of the
animals that feed upon them ; so that any one experienced
and observant can tell, by the presence of certain plants and
the absence of others, whether horses, cattle, or sheep have been
the exclusive or predominant animals that have grazed upon it.
Another point of some importance is the greater stability
in the flora of meadow as compared with that of pasture land.
In the former only one plant was an accidental straggler, while
in the latter there were 12, or two-thirds of the peculiar spe-
cies. These are mostly rare, and are very often not truly Brit-
ish plants, so that they cannot be considered as permanent
pasture plants. The more stable meadow flora is no doubt
largely due to the fact that few of the late-flowering plants
are allowed to produce seed, and though seed may be often
introduced by birds or the wind, many of these species soon
die out. It thus appears that though pastures are actually
richer in species than meadows, yet the latter have a more
permanent character, as almost all those peculiar to pastures
are comparatively rare and therefore very liable to disappear
through very slight changes of conditions.
These various facts, and many others which cannot be here
given, serve to show us how very delicate are the mutual rela-
tions and adjustments of plants to their total environment.
In proportion as that environment is subject to change of any
kind, some rare species die out, while others become diminished
in numbers. And what takes place in single fields or other
small areas, when closely studied, must certainly occur on a
much grander scale over the whole earth, and especially in
those countries and periods when great changes of climate or
of physical geography are taking place. These detailed studies
of " Meadow and Pasture Analysis " — as their author terms
them — thus demonstrate on a very small scale that " struggle
18 THE WOELD OF LIFE
for existence " which, as we shall see further on, is always
present, acts in an almost infinite number of ways, and is one
of the most important factors in the developmental changes
of the World of Life. We will now proceed to give some of
the numerical facts of plant distribution, in various areas small
and large, as well as over the whole earth; but it will be ad-
visable first to give a brief account of the way in which this
is usually dealt with by botanists.
Four years before the appearance of the Origin of Species
the great Swiss botanist, Alphonse De Candolle, published one
of the most remarkable and interesting botanical works in
existence, his GeogTaphie botanique raisonnee, in two thick vol-
umes. He not only brought together all the then available
facts as to plant distribution in every part of the world, studied
them from almost every point of view, and grouped them in
relation to every known agency that might be supposed to influ-
ence their distribution, but at every step he most carefully
and ingeniously discussed the problems involved, often of a
very intricate nature, with a view to arriving at a more or less
complete explanation.
It is impossible here to give any adequate notion of this
great work, but a few of the chief subjects treated may be
mentioned. The effects of temperature and of light upon the
growth and vitality of plants are first examined, and some
very interesting conclusions are reached, among others the great
importance of the time during which any particular degree
of heat continues. This discussion occupies the first three
chapters. Sixteen long chapters then deal with " Botanical
Geography," in which all the geographical conditions that affect
the distribution of plants are elaborately discussed, such as alti-
tude, latitude, aspect, humidity, geological and mineralogical
causes, both in their direct and indirect action, and as apply-
ing to cultivated as well as ^vild plants. The areas occupied
by species, both as regards size and shape, are then discussed,
and the causes that lead to their variations investigated. He
then shows what are the actual areas in various parts of the
DISTRIBUTION OF SPECIES 19
world, and under various geographical conditions, and thus
arrives at the causes of great extension of certain species from
Vilest to east in the north temperate zone, or along sea-shores
or river-banks in the tropics ; while the normal area is consid-
ered to be '^ massive " rather than elongated.
Coming then to detailed facts, he shows that about 200
species (out of the total then known of about 120,000) have
areas equal to one-third or more of the entire land surface of
tlie globe. Further, in certain Families (usually called ^Nat-
ural Orders) there are plants which range from the Arctic
regions to the southern extremity of the great continents.
Among the former are our common Marsh Marigold (Caltha
palustris) and Common Sundew (Drosera rotund i folia), which
are found in all Northern Europe, Asia, and America ; while
our common Sowthistle (Sonchus oleraceus) is found scattered
over the whole globe, tropical as well as temperate, and is per-
haps the nearest of any known plant to being truly cosmopol-
itan.
By a laborious comparison the author arrives at the con-
clusion that the average area occupied by the species of flower-
ing plants is rroth part of the whole land surface of the globe.
But the area varies enormously in different parts of the world.
Thus, in the wdiole Russian Empire, species have a mean area
of irVth the land surface, owing to the fact that so many range
east and west over a large part of Europe and Xorth Asia ;
while in South Africa the mean range is only W&oth of that
surface, which expresses the fact of the extreme richness of
the latter flora, many of the species composing w^hich have
extremely restricted ranges. He also reaches the eonclusion
that in passing from the pole to the equator the mean areas
of the species become smaller. A few examples of very lim-
ited areas are the following : — Several species of heaths are
found only on Table Mountain, Cape of Good Hope; Cam-
immda isopliylJa grows only on one promontory of the coast
of Genoa; the beautiful Alpine Gromwell (Lithospermum
Gastoni), on one cliff in the Pyrenees; Wulfenia Carintliiaca,
20
THE WORLD OF LIFE
on one mountain slope in Carintliia ; Primula imperialis, on
the summit of Mount Pangerago in Java, and many others.
In order to compare the plants of different parts of the world
in their various relations, De Candolle divides the whole land
surface into fifty botanical regions, each distingTiished by the
possession of a considerable proportion of peculiar species of
plants. These regions are of greatly varying extent, from Xo.
18, comprising the whole of Xorthern Asia, to Xo. 10, limited
to the small island of Tristan d'Acunha in the South Atlantic.
The list is as follows : —
A. De Candolle's Botaxical Regions
1. Arctic zone.
2. Europe, temperate.
3. Mediterranean.
4. Azores, Madeira, Canaries.
5. Sahara, Cape Verde Islands.
6. Guinea N., Soudan.
7. " S., Congo, Benguela.
8. Island of St. Helena.
0. South Africa.
10. Tristan d'Acunha.
11. Islands of Kerguelen, St. Paul,
etc.
12. Madagascar, etc.
13. Mozambique, Zanzibar.
14. Abyssinia to Egypt.
15. Persia, Euphrates.
16. Caucasus, Armenia.
17. Tartary east of Caspian.
18. Siberia, Ural to Kamschatka,
Lake Aral.
19. Asia Central.
20. Afghanistan to Indus.
21. Nepal to Bhutan.
22. China, Japan.
23. Philippines.
24. Siam, Cochin China.
25. Burma and Assam.
26. Bengal, Ganges.
27. Peninsular India, Ceylon.
28. Malacca, N. Ireland.
29. Australia, New Zealand.
30. Fiji to Marquesas.
31. Mariannes, Carolines.
32. Sandwich Islands.
33. N.W. America.
34. Canada and United States.
35. Texas, California, Mexico.
36. West India Islands.
37. Venezuela.
38. Colombia.
39. Peru.
40. Galapagos.
41. Bolivia and Andes.
42. Guayanas.
43. Amazonia.
44. Brazil N.E.
45. "" W., Paraguay.
46. " S.E.
47. Uruguay, La Plata.
48. Chile, Juan Fernandez.
49. Patagonia, Falkland Islands.
50. The Antarctic Archipelago.
By an extensive comparison of floras all over the world it
is found that less than Ave per cent, of the total of the kno^vn
species are found in more than two of these regions. Fam-
DISTRIBUTION OF SPECIES 21
ilies which have very few annual species show a still smaller
percentage (three per cent) ; while those whose species are mostly
trees or shrubs have less than two per cent which extend to
more than two regions.
He also finds that those with fleshy fruits have a wider dis-
persal than those with dry fruits, and those with very small
seeds, wider than those with larger seeds. Eighteen species
only are found to be spread over half the land surface of the
globe. There are no trees or shrubs among these; grasses are
most abundant among them ; and composites — the daisy and
aster family — the least ! This last conclusion seems very
strange in view of the fact that this family has its seeds so
frequently provided with special means of dispersal, either by
the wind or by animals. But he also points out, what is now
well known to botanists, that the species of Compositse are not
usually very widely spread ; and also that several other natural
orders in which the seeds are usually winged for wind-dispersal
are not more widely distributed than those whose seeds are
not winged. These facts certainly prove that the dispersal of
seeds by wind or by birds has been brought about for the pur-
pose of securing ample means of reproduction Avithin the area
to which the whole plant has become specially adapted, not
to facilitate its transmission to distant lands or islands which,
only in a very few cases, would be suited for its growth and
full development. Very extensive dispersal must, therefore,
in most cases be looked upon as an adventitious result of gen-
eral adaptation to the conditions in which a species exists.
De Candolle's work also treats very fully the subject of the
comparative preponderance of the various natural orders of
plants in different regions or countries. This mode of study-
ing plant-distribution was introduced by our greatest English
botanist, Robert Brown, and it is that most generally used by
modern botanical writers on distribution. It consists in the
characterisation of the vegetation of each region or district by
the proportionate abundance in species belonging to the dif-
ferent natural orders.
22 THE WOKLD OF LIFE
This is used in many different ways. In one the minimum
number of orders whose species added together form one-half
of the whole flora are given. Thus, it was found that in the
Province of Bahia (Brazil) the 11 largest natural orders com-
prise half the whole number of species. In British Guiana
12 orders are required, and in British India 17. Coming to
temperate regions, in Japan there are 16, in Europe 10, in
Sweden 9, in Iceland and in Central Spain 8. The general
result seems to be that those regions which are very rich in their
total number of plants require a larger number of their pre-
ponderant orders to make up half the total flora ; which implies
that they have a larger proportion of orders which are approxi-
mately equal in number of species.
Another mode of comparison is to give the names of the
first three or four, or even ten or twelve, of the orders which
have the greatest number of species. It is found, for example,
that in equatorial regions LeguminossB usually come first,
though sometimes Orchids are most abundant ; in temperate
regions the Composites or the Grasses; and in the Arctic,
Grasses, followed by Crucifera? and Saxifrages. A few of the
tables constructed by De Candolle are given as examples.
British Guiaxa ( Scliomburgh )
3254 species
Leguminosae 469 species
Orchidese 214 "
Rubiacege 176 "
Melastomaceae 126 "
The Andes of New Grenada (Humboldt)
1041 species
Composite 86 species
Leguminosae 65 " '
Rubiacese 49 "
Graminese 42 "
Orchidese .it,,. • 41 "
DISTKIBUTION OF SPECIES
23
Australia and Tasmania (R. Brown)
4200 species
Legiiminosse
Euphorbiacese
Compositae
Orchidese
Cyperaceae
Giaminese
Myrtaceaj
Proteacese
Iceland.
1. Cyperaceae 47
2. Graminese 45
3. Compositae 24
4. Caryophylleae 23
5. Cruciferae 21
6. Amentaceae 20
402 species
7. Saxifrageae 15
8. Rosaceae 15
9. Ericaceae 12
10. Juncaceae 12
11. Ranunculaceae 11
12. Polygoneae 11
As a short general conclusion De Candolle says:
The Leguminosae
The Composites ,
The Grasses . .
. . dislike cold.
, . dislike cold and wet.
dislike drought.
Other examples will be given when discussing the compara-
tive relations of the various temperate and tropical floras of
the world.
CHAPTER III
THE NUMEEICAL DISTRIBUTION OF BRITISH PLANTS I TEMPERATE
FLORAS COMPARED
Proceeding from the more to tlie less familiar regions we
will be^rin witli a few of the facts as to the flora of our own
country. Partly owing to its insular character, and also be-
cause it has few lofty mountains or extensive forests, the num-
ber of species of flowering plants is somewhat (but not much)
below that of most continental countries of equal area. It con-
tains about 1800 species, as a rough mean between the estimates
of dift'erent botanists.^ It may seem curious that there should
be any such difference of opinion, but one of the facts that
have alwa^^s been adduced as showing that species are not fixed
and immutable entities is the frequent occurrence of varieties,
which are sometimes so peculiar and so apparently constant
that they are treated by some botanists as distinct species, by
others as sub-species, and by others again as forms or varieties
only. These modifications of a species are usually confined to
a more limited area than the species itself, and are occasionally
connected with each other or with the parent species by inter-
mediate forms. Again, when these varieties are cultivated,
and esjDecially when a large number of plants are raised from
their seeds, they are apt to revert partially or wholly to the
parent form. Another source of difference of opinion among
botanists is, as to the treatment of those plants, found usually
near human habitations, which are supposed to have been orig-
inally introduced, either purposely or accidentally, from foreign
coimtrios. Such are the wild Larks])ur and Monkshood, the
1 In all the tables and comparisons of " Ploras " in this work, unless
where ferns are specially noted, flowering plants only are intended, even
when the term '* plants " is used.
24
TEMPERATE FLORAS
25
Red Valerian, the Balm, the Martagon Lily, and many others.
This explanation is necessary in order to avoid any supposition
of positive error when the figures here given do not agree
with those of anv of the text-books or local floras.
xJ
The chief diiferences arise, however, from the increased
study of certain difficult groups leading to the separation of
large numbers of slightly differing forms, that hardly any
one but an expert can distinguish, as distinct species. The
most important of these are the Brambles (the genus Rubus)
and the Ilawkweeds (the genus Hieracium). During the last
thirty years the numbers of these have more than doubled,
according to the standard authority for British botanists —
The London Catalogue of British Plants. The numbers in
an early and late edition are as follows : —
Genus.
7th Ed., 1877.
lOth Ed., 1908.
Rubus
54 species
48
1
1
116 species
133 "
Hieracium
Euphrasia
15
Rhinanthus
8 "
In the last two cases two well-known plants — the little
" eyebright " of our turfy banks, and the '' yellow rattle " of
peaty meadows, which have been each considered to form a
single species from the time of Linnseus to that of Bentham
and Hooker — are now subdivided into a number of distinct
species, each claimed to be well recognisable and constant.
With such rapid changes in the estimate of species in so
well-known a flora as our own it may be thought that the
number of species in foreign countries is even more uncertain.
This, however, is by no means the case, as tlio great
majority of the species of plants a^ well as of animals; offer
little difficulty, and present few fixed varieties (though
abundance of variation), so that for general comparisons the
D. H. HILL LIBRARY
26 THE WORLD OF LIFE
figures obtainable are very fair approximations, and give us
interesting and valuable information.
About one-third of the total numbe'r of our species of
wild flowering plants belong to what the late Mr. H. C. Watson
termed the British type ; that is, they are found in suitable
places over the whole of Great Britain, and in most districts
are so plentiful that they may be termed common plants —
such are the Alder, Birch, and Hazel among trees and shrubs ;
the Honeysuckle, Ivy, Heather or Ling, Daisy, Chickweed,
!N^ettle, and a host of others. Another gi'oup is abundant
in England, but absent from the Highlands or from Scotland
generally, such as the Dwarf Gorse and Yellow Dead-Nettle.
Several arctic or alpine plants are peculiar to the Highlands,
a considerable number of species are found only in our
eastern counties, while as many or more are characteristic of
the west.
More curious perhaps than all these are the cases of
plants found only in one small area, or two or three isolated
patches ; and of others which are limited to a single station,
sometimes of a few acres or even a few yards in extent.
Such are the Cotoneaster, found only on Great Orme's Head
in ]^. Wales; the Yellow Whitlow-Grass, on Worms Head
in S. Wales ; the pretty white-flowered Potentilla rupestres,
on a single mountain-top in Montgomeryshire; the small
liliaceous plant, Simetlius hicolor, in a single grove of pine
trees near Bournemouth, now probably exterminated by the
builder, and another plant of the same family, Lloydia
serotina, limited to a few spots in the Snowdon range ; the
beautiful alpine Gentiana verna, in upper Teesdale, Yorkshire,
and others confined to single mountains in the Highlands.
Between the extremes of widespread abundance and the
greatest rarity, every intermediate condition is found ; and
this is, so far as we know, a characteristic of every part of
the world. This, again, affords a striking proof of that
struggle for existence which has already been referred to,
acting, as Darwin was the first to point out; first to limit the
TEMPEEATE FLOKAS
27
range of a species, often so that it exists only in two more or
less isolated areas, then to diminish the number of individuals
in these areas, and finally to reduce them to a single group
which ultimately succumbs to an increased stress of competi-
tion or of adverse climatal changes, when a species which
may have once been flourishing and widespread akogether
ceases to exist. The rarity of a species may thus be
considered as an indication of approaching extinction.
Numerical Distribution of Plants hi Britain
We will now give a few numerical statements as to the
comparative abundance of the species of plants in large and
small areas in various parts of the world, such facts having a
special application to the theory of evolution. The 55
counties of England and Wales (counting the three Ridings
of Yorkshire as counties) have usually areas from 500 to
2500 square miles; and a considerable number of them
have had their plants enumerated in special catalogues or
floras. The following are the approximate numbers of the
flowering plants in a few of these : —
Statistics of County Floras
County.
Area, Sq. Miles.
No. of Species.
Carnarvonshire
563
1357
980
1533
790
1612
840
636
1519
2638
233
2658
1056
Cornwall
1140
Dorsetshire
1010
Essex
1010
Glamorganshire
950
Hampshire
1150
Herefordshire
865
Hertfordshire
890
Kent
1120
Lincolnshire
1200
Middlesex
835
West Yorkshire
995
Mean of the 12 counties
1198
1026
Great Britain
87,500
1800
28
THE WOELD OF LIFE
This table of the distribution of plants in our counties
is very instructive, because it shows us the influence of
diversity of soils on the number of species that can grow
and maintain themselves naturally as wild plants. This is
largely dependent on the extreme diversity of the geology of
our island, almost every geological formation from the oldest
to the most recent being rej^resented in it. This variety of
soil seems to be much more important than diversity of sur-
face due to altitude, so that our lowland counties are quite
as rich as those which are hilly or mountainous. Again, we
see that, within moderate limits, greater area has little in-
fluence on richness of the flora, the largest. West Yorkshire,
having only about one-fifth more species than the smallest,
Middlesex, with only about one-twelfth the area.
The preponderating importance of variety of soil and sur-
face conditions affording good stations for plants, such as
woods, hedgerows, streams, bogs, etc., is well shown by a few
special comparisons that have been made by experienced
botanists.
The Parish of Cadney (Lincolnshire), a little over 3 square
miles in area, has 720 species of flowering plants; the county
nearly 900 times as large, having 1200.
The Parish of Edmondsham (in Dorsetshire), covering less
than 3 square miles, has 640 species ; the county, 340 times
as large, having 1010 species.
An equally remarkable instance was given by Mr. H. C.
Watson fifty years ago, and no doubt from his own observa-
tions, as he resided in the countv.
Area,
Sq. Miles.
Species.
Surrey
760
60
10
1
840
An area in Surrey of
660
600
" at Thames Ditton, Surrey. • -
400
TEMPEEATE FLOIUVS 29
Here we see that 10 square miles coutaiiied nearly as many
species as 60, and nearly two-thirds the nmiibcr in TOO square
miles ; while the single square mile produced nearly half the
number in the whole county.
Taking still smaller areas, Mr. Woodruffe-Peacock found
fields in Lincolnshire and Leicestershire, of from 10 to 25
acres, to yield from 50 to 60 species of plants ; while a plot
of 16 Vo feet square (or 1 perch) would usually have 20 to .')0
species. Old and long-disused stone-quarries are often very
rich, one of about two acres producing sometimes as many
species as the fields of eight or ten times the area. On a plot
of turf 3 feet by 4, at Down in Kent, Mr. Danvin found 20
species of flowering plants growing.
These facts of the distribution of plants in our own is-
lands prove, that for moderately large areas in the same
country possessing considerable diversity of soil and general
conditions affecting plant-life, the majority of the species are,
as a rule, so widely scattered over it that approximately similar
areas produce a nearly equal number of species. Further,
we find that areas of successively smaller and smaller sizes have
a very much greater number of species relatively than larger
ones ; so that, as we have seen, 10 square miles may show al-
most as much variety in its plant-life as an adjacent area
of 60 square miles, and that a single square mile may some-
times contain half the number of species foimd in 700 square
miles.
This characteristic of many small areas being often much
richer in proportion to area than larger ones of which they
form a part, is a necessary result of the great differences in
the areas occupied by the several species and the numbers
of the individuals of each ; from those very common ones which
occur abundantly over the whole country, to others which, al-
though widespread, are thinly scattered in favourable situa-
tions, down to those exceptional rarities which occur in a very
few spots or in very small numbers. Those spots or small
areas which present the most favourable conditions for plant-
30 THE WORLD OF LIFE
life and are also most varied in soil, contour, water-supply,
etc., will, when in a state of nature, be occupied by a large
proportion of the common and widespread plants, together
with so many of the less common or the rare species which
find the requisite conditions in some part of its varied soil
and aspects, as to produce that crowding together of species
and luxuriance of growth which are such a joy to the botanist
as well as to the less instructed lover of nature.
All these peculiarities of vegetation are to be met with in
every part of the world, and often in a more marked degree
than with us. But this depends very much on diversities of
climate and on the extent of land surface on which the entire
flora has been developed. The total number of species de-
pends mainly on these two factors, and especially on the
former. The variety of species is small in arctic or sub-arctic
lands, where the long and severe winter allows of only certain
forms of vegetable and animal life; and it is equally if not
more limited in those desert regions caused by the scarcity
or almost complete absence of streams and of rain. It is most
luxuriant and most varied in that portion of the tropics where
the temperature is high and uniform and the supply of mois-
ture large and constant, conditions which are found at their
maximum in the Equatorial Zone within twelve or fifteen
degrees on each side of the equator, but sometimes extend-
ing to beyond the northern tropic, as on the flanks of the
Himalavas in north-eastern India, where the monsoon winds
carrv so much moisture from the heated Indian Ocean as to
produce forests of tropical luxuriance in latitudes where most
other parts of the world are more or less arid, and very often
absolute deserts.
Temperate Floras compared
I will now endeavour to compare some of the chief floras
of the Temperate Zone, both as regards the total number of
species in fairly comparable areas, and the slight but clearly
TEMPERATE FLOEAS
oi
marked increase of the number in more southern as compared
with more northern latitudes.
I will first show how this law applies even in the com-
paratively slight difference of latitude and climate within our
own country. Dividing Great Britain (without Wales) ^ into
three nearly equal portions — Scotland north of the Forth and
Clyde, Mid-Britain, and South Britain, including all the
southern counties; with areas of 22,000, 26,000, and 31,000
square miles — the number of species (in 1870) was, respec-
tively, 930, 1148, and 1230. At the same period the total of
Great Britain was 1425 species. These figures are all ob-
tained from Mr. H. C. Watson's Cybele Britannica, and must
therefore be considered to be fairly comparable. We see here
that the whole of the Scottish Highlands, with their rich alpine
and sub-alpine flora, together with that of the sheltered valleys,
lakes, and mountainous islands of the west coast, is yet de-
cidedly less rich in species than Mid-Britain, while both are
less rich than South Britain, with its more uniforai surface,
but favoured with a more southern climate.
The following table shows these facts more distinctly : —
Area,
Square Miles.
No. of
Species.
North Britain
22,325
26,550
31,050
930
Mid-Britain, Lowlands south to Stafford -^
and Leicester J
South Britain ( Wales excluded )
1148
1230
The above figures have been kindly extracted from Wat-
son's volume by my friend the late Mr. W. H. Beeby.
Making a comparison of some countries of Europe we have
similar results more clearly shown.
1 Wales is omitted in order to make the three divisions more equal, and
contrasted in latitude only.
32
THE WOELD OE LIEE
Floras of Europe, showing Influence of Latitude
Countries.
Europe
Lapland
Scandinavia and
Denmark . . . .
Sweden
Britain
Germany
Switzerland . . .
France
Italy
Sardinia
Sicily
Area.
Square Miles.
No. of
Species.
;3,850,000
150,000
456,000
173,000
87,500
208,000
16,000
204,000
91,400
9,300
9,940
9500
500
1677
1165
1860
2547
2454
4260
4350
1770
2070
Nyman
A. De Candolle
((
Lend. Cat., 1895
Garehe, 1908
Schinz and Kellar, 1908
Coste, 1906
Beccari
The above table shows us a continuous and well-marked
increase as we go from north to south, the irregularities in
this increase being well accounted for bj local conditions and
by allowing something for differences of area. Sweden is so
much poorer than Britain, owing to its having been completely
ice-clad during the glacial epoch, while much of southern Brit-
ain was free. Gennany is poorer than Erance, partly on
account of its severer continental climate, but also owing to
Erance possessing a greater variety of surface, owing to its
including a portion of the loftiest Alps in the south-east, the
isolated Pyrenees in the south, the Jura and Vosges mountains
on the north-east, and its central volcanic ranges, together with
its southern Mediterranean coast, and a very extensive west-
ern and northern coast-line. It also has a more diversified
soil, owing to far less of its surface being buried under glacial
debris. Italy has still greater advantages of a similar kind,
and its slight superiority to Erance, with less than half the
area, is about what we should expect. It well illustrates the
fact, already ascertained, that difference of area within moder-
ate limits is of far less importance than comparatively slight
advantages in soil and climate.
TEMPERATE ELOEAS
33
Turning now to N'orth America, the following figures from
the latest authorities have been supplied by my friend Mr.
J. D. A. Cockerell : —
state.
Montana and Yellowstone
Park
Nebraska
Colorado
California
Area,
Square Miles.
150,000
118,000
104,000
158,000
No. of
Species.
1934
1478
2872
2700
Remarks.
Data in 1900
1898
1900
" recent
Two subdivisions of the eastern United States show well the effects
of latitude.
Central and north-east ~
States — Michigan to L
736,000
32r98
Recent estimate
Virginia, Kentucky
South-east United States ....
630,000
6321
et ((
The number of species in proportion to area and position
is apparently less than in Europe, though the corresponding
latitudes are farther south. Germany and Switzerland com-
bined, with an area less than one-third of the north-eastern
and central States, have about as many species ; while Erance,
in about the same average latitude, but with less than one-
third the area, has considerably more. The south-eastern
States extending to 30° S. lat. have about the same number
of species as Europe from the Alps and Carpathians south-
ward, while the area of the latter is very much smaller and
its latitude about eight degrees farther north.
The whole Mediterranean flora was estimated bv Griesbach
and Tchikatcheff, in 1875, to comprise 7000 species in an area
of about 550,000 square miles ; so that the best comparisons
that we can make between large European and American areas
show a decided superiority in the former. This is no doubt
partly due to the much severer winter climate in correspond-
ing latitudes of !N'orth America ; and perhaps the long per-
84 THE WORLD OE LIFE
sistence of siicli conditions before the glacial period may be
the main cause of the whole phenomenon.
It is, however, in temperate Asia that we find what seem
to be the richest extra-tropical floras, at least in the north-
ern hemisphere. The great work of Boissier, Elora Orientalis
(1880), describes 11,876 species in the region of East Europe
and South- West Asia, from Greece to Afghanistan inclusive,
the area of which may be roughly estimated at 2,000,000
square miles. It is a region of mountains and deserts inter-
mingled wdth luxuriant valleys and plains, and almost trop-
ically warm in its southern portion. So much of it is diffi-
cult of access, however, that the collections hitherto made
must fall far short of being complete. Its extreme richness
in certain groups of plants is showm by the fact that Boissier
describes 757 species of Astragalus or Milk-vetch, a genus of
dwarf plants spread over the w^hole northern hemisphere, but
nowhere so abundant as in this region. Europe has 120
species. •
The only other extensive area in temperate Asia the plants
of which have been largely collected and recently catalogued
(by Mr. W. B. Ilemsley of the Kew Herbarium) is China
and Corea, occupying a little more than 1% million square
miles. The enumeration, completed in 1905, shows 8200
species of flow^ering plants actually described. But as large
portions of this area have never been visited by botanists,
and as new species w^re still flowing in rapidly at the close
of the enumeration, there can be little doubt that the total
will reach, before many years have elapsed, 10,000 or per-
haps 12,000 species. It is, moreover, an area that is es-
pecially rich in trees and shrubs, and as these are less col-
lected by the travelling botanist than the herbaceous plants,
it becomes still less easy to speculate on the actual number
of species this country really contains. Japan, which is prob-
ably better known, has about 4000 species in less than one-
tenth the area, and is thus a little richer than Erance. It
TEMPERATE ELOEAS 35
agrees, however, very closely with the AVestern Himalayas as
estimated by Sir J. D. Hooker.
Coming to the southern hemisphere, we find several ex-
amples of exceedingly rich floras. The first to be noticed is
Chile, where, in an area of 250,000 square miles, 5200 species
of flowering plants have been found. In Australia, Xew South
Wales, with an approximately equal area, has 3105 species,
while West Australia has 3242 species in what is probably
not more than one-fourth the area, as so much of that Colony
is absolute desert.
But richer than either of these is extra-tropical South
Africa, where, in about a million square miles, 13,000 species
are known, and there are still probably many to be added.
The richest portion of this area is the Cape Eegion, as de-
fined by Mr. H. Bolus, where, in 30,000 square miles, there
are about 4500 species of flowering plants. This area is the
same as that of southern Britain, and about one-third that of
West Australia excluding the tropical portions and the desert.
All these rich areas in the southern hemisphere agree in
one respect, they are limited inland hj mountains or deserts,
and their coast-line is bordered by a considerable extent of
sea less than 1000 fathoms deep, and another still larger
extent under 2000 fathoms. There is thus a high prob-
ability that in all these cases the flora was originally
developed in a much larger and more varied area, and that
it has been, in comparatively recent times, very greatly re-
duced in extent, thus crowding the various species together.
This has, no doubt, caused the extinction of some, while
others show that they are on the road to extinction by their
limitation to very narrow areas, as is especially the case with
many of the orchids, the heaths, and other characteristic
South African groups. Of course the mere submergence of
a large amount of lowlands would not, of itself, enable any
of its plants to invade the adjacent undisturbed land; but
the subsidence would no doubt have been very slow, and
36
THE WOELD OE LIFE
might have included the degradation of lofty mountains.
It Avould also be accompanied by a lowering of some of the
existing area. This would modify the climate in various
ways, leading probably to a higher temperature and more
moisture, thus giving more favourable conditions generally
for a great variety of plants.
For easy reference it may be well to give here a table
showing the main facts as to these warm-temperate floras.
Warm-Temperate Floras compared
Northern Hemisphere
Country.
S.E. United States.
Mediterranean
Greece to -j
Afghanistan j
China and Corea. . .
Japan
Himalayas, West. . .
Algeria
Area,
Square Miles.
630,000
550,000
2,000,000
1,500,000
150,000
150,000
150,000
No. of
Species.
6,321
7,000
11,876
8,200
4,000
4,000
2,930
T. D. A. Coekerell
Tchikateheff
Boissier, Flora
talis, 1880
Hemsley, 1905
Havati, 1908
Hooker, 1906
Matthews, 1880
{
Orien-
Chile
Souther
250,000
310,700
? 90,000
88,000
26,380
103,650
1,000,000
30,000
n Eemiepheri
5,200
3,105
3,242
1,830
965
1,474
13,000
4,500
?
•
N.S. Wales
W. Australia
Victoria
Miiller
r " (tropics and
\ deserts omitted )
Miiller
Tasmania
ii
New Zealand
South Africa
The Cape Region . .
Cheeseman, 1906
Thomer's Census
H. Bolus, 1886
Temperate Floras of Smaller Areas compared
We will now deal with a series of smaller areas (com-
parable to our counties) which I have been able to collect
from various parts of the world ; and I propose to arrange
them in order of latitude, from north to south, so as to show
still more distinctly the influence of climate. Each main
TEMPERATE ELOEAS
37
division of the globe will be considered separately for
convenience of reference, and we begin with Europe, for wbicli
materials are the most accessible, though still far from abun-
dant.
The recent publication of a flora of Harjedal, a province
of central Sweden, with a mountainous surface and abundant
forests, shows how poor is a sub-arctic area which has
recently been buried under an ice-sheet. The real wonder is
that it should have acquired so rich a flora by the natural
means of dispersal from more southern lands.
Temperate Floras of Small Areas in Europe
Locality.
I
C
<
a,
Harjedal (Sweden), lat. 61°-64'
Malvern Hills
Hertford (near)
Strasburg, lat. 48 J °
Schaflniiausen
Thurgau
Basel
Zurich
St. Gallen
r Schwyz, Uri, Underwalden ,
< Glarus
I Uri
r Grisons ,
^ Valais, 464°
tTicino, 46J°
Ofengebietes, Grisons
Vallee de Joiix, Jura ,
Bergunerstocke, Engadine
Poschiavo, S. of Bernina Pass ...
Euganean Hills, Padua
Susa, Piedmont (Beccari)
Ferrara, Valley of Po (Beccari)
Mytilene (Lesbos) (Candargy) . .
Area,
Sq. Miles.
No. of
Species.
5375
606
120
802
80
810
120
960
114
1220
381
1006
163
1117
666
1151
779
1295
950
1352
267
1100
415
1160
2773
1550
2027
1752
1088
1504
86
797
100
823
47
873
92
1200
795
1400
540
2203
1012
794
675
1249
Remarks.
Birger. 1908
De Candolle
((
a
H. H. Field
((
it
it
it
it
it
it
a
Lat. 46°40'
Lat. 46°40'
Lat. 46°30'
46°20'
45°30'
45° 10'
44°50'
39°00'
(I am indebted to Mr. Herbert H. Field for all the data
in this table, except where otherwise stated. They are from
38 THE WOELD OF LIFE
the original authorities, and he has kindly brought them
up to date as far as possible, so that they may be fairly com-
parable.)
Although very unequal in extent, the various Swiss
cantons, which form the bulk of this table, are remarkably
similar in their botanical riches, the smallest, most northerly,
and least alpine (Schaffhausen) having more than two-thirds
the number of species of the Valais, the most southerly,
nearly the largest, and the most alpine, the main chain of
the Alps for nearly 100 miles forming its southern boundary,
and the Bernese Alps its northern, But Schaffhausen geo-
graphically connects eastern France wdth western Germany,
and partakes of the rich flora of both countries. This table
of the Swiss cantons is also very interesting in showing us
that alpine floras are really no richer in species than those
of the lowlands, if we compare approximately equal areas.
A remarkable illustration of this is the comparison of the
Ofengebietes, a district including snowy peaks, forests, and
lowland meadows, having almost exactly the same number
of species as an equal area near Strasburg, or one around
the town of ITertford ! Switzerland, thouirh so verv unlike
Great Britain in situation, climate, and physical conditions
generally, yet reproduces in its cantons that curious uni-
formity in species-production that we found to be the case
in our counties. But as Switzerland, though only one-fifth
of our area, has a gTeater number of species by one-third,
that superiority is, as a rule, reproduced in its subdivisions.
Susa, in Piedmont, wdth its fertile valleys and snowy Alps,
has by far the richest flora of the whole series, due to its
w^arm climate, variety of surface, and complete shelter from
the north. Mytilene, the farthest south, has doubtless been
impoverished botanically by its large population and extensive
fruit culture.
It is, I think, clear that, other things being equal, an
alpine flora is not at all richer than a lowland one ; but, as
we shall see further on, there are indications that the high
TEMPERATE FLORAS 39
alpine flora really partakes of that poverty wliicli appertains
to liigii latitudes. It is the novelty and beauty of alpine
plants that are so attractive to the botanist and so entrancing
to the lover of nature, that give an impression of abundance
which is to some extent deceptive, and this is increased by
the fact that Avhole groups of plants which are more or less
rare in the lowlands are plentiful at higher altitudes. Two
other circumstances add to this impression of abundance —
alpine flowers are mostly very dwarf, and being all at the
same level, attract the eye more than when distributed over
various heights from that of the creeping herb to the summit
of lofty trees ; and, in addition to this, the shortness of the
season of growth leads to a much larger proportion of the
species flowering together than on the lowlands at the same
latitude.
Extra-European Temperate Floras
The number of floras which are available for comparison
with those of Europe are few in number and yqxj widely
scattered ; but they serve to illustrate the fact already dwelt
upon, that the dift'erences of species-j^opulation in fairly com-
parable areas approach to a general uniformity all over the
world.
Boulder County is probably one of the most favourably
situated areas in the United States. It is onlv a little west
of the centre of the country; it comprises warm valleys and
one of the highest of the Rocky Mountain summits. Long's
Peak, and being in the latitude of southern Italy and Greece,
has abundant sunshine and a warm summer temperature.
It thus agrees in physical conditions with some of the alpine
cantons of Switzerland, and the number of its flowering
plants is almost identical with the average of Zurich, St. Gall,
Schwyz, etc., which have almost the same mean area.
Washington, D.C., with an undulating surface just above
the sea-level, and a fair amount of forest and river-swamp,
agrees very well with the mean of Strasburg and Schaff-
40
THE WOKLD OF LIFE
Extra-European Temperate Floras. Small Areas.
Lat.
40°N.
39°N.
37°N.
37°N.
35 °S.
35*S.
34°S.
32rs.
27rS.
27J°N.
Country.
North America.
Boulder Co., Colorado. . .
Washington, D.C
Japan.
Mount Nikko
Mount Fujiyama
South Africa.
Cape Peninsula
Aust7nlia.
Illawarra, N.S.W
Cumberland Co., N.S.W. .
Mudgee (Wellington Co.)
Brisbane, Q
North India.
Temperate Sikhim
Area
Sq. Miles.
751
108
360
520
197
200
1400
600
800
1800
No. of
Species.
1200
922
800
730
1750
829
1213
631
1283
2000
Remarks.
Cockerell
Ward
Hayati
Bolus
A. G. Hamilton
W. Woolls
A. G. Hamilton
Jas. Wedd
Hooker
liausen, somewhat similarly situated, but at a higher latitude.
The two mountain areas in Japan, which Mr. Hajati
informs me have been well explored, show an unexpected
poverty in species, being much below any of the Swiss cantons
of equal area. This is the more remarkable as Japan itself
is equal to the most favoured countries in Europe — France
and Italy; and this again indicates the combined effect of
altitude and insularity in diminishing species-production, the
lower parts of these Japan mountains being highly cultivated.
In the southern hemisphere we come first to the Cape
Peninsula, as limited by Mr. Bolus, and often thought
to be the richest area of its size in the world. There are 80
species of heaths and nearly 100 species of orchises in this
small tract only a little larger than the Isle of Wight. 'No
other similar area in the temperate zone approaches it,
though it is possible that an equally rich area of the same
extent might be found in temperate Sikhim, where several
TEMPEEATE ELOEAS 41
distinct floras meet and intermingle. But as the Valais is
nearly as rich as Sikhim, and Susa with one-fourth the area
is still richer^ it is quite possible that smaller areas may
be found as rich as that of the Cape Peninsula. The best
third of the Susa district would probably approach closely
if it did not quite equal it. Temperate Australia is another
country which has obtained a high reputation for its floral
riches, for much the same reason as the Cape of Good Hope.
In 1810 Robert Brown made known the extreme interest
of the Australian flora, both from its numerous hitherto un-
known types of vegetation and the variety and beauty of its
flowering shrubs. It was therefore supposed that the country
was not only botanically rich in new species and genera, but
actually so in the number of its species in proportion to area,
and this may really be the case with limited portions of West
Australia (for which I have been able to obtain no detailed
information), but is certainly not the case for Xew South
Wales, Victoria, or Tasmania. Cumberland County, which
contains Sydney and the celebrated Botany Bay, is only a
little richer than our counties of about the same area, while
the celebrated district of Illawarra only produces about the
same number of plants as does Middlesex, which has, ex-
clusive of London, a less area. Many parts of Europe in a
similar latitude are much more productive.
There is, however, one world-wide group of plants in
which, as regards small areas, eastern temperate Australia
seems to be pre-eminent — that of terrestrial Orchids. Mr.
H. Bolus, in his work on the Orchids of the Cape Peninsula,
states that there are 102 species in an area of 197 square
miles ; and he quotes Mr. Eitzgerald, the authority on the
Orchids of Australia, that " within the radius of a mile '' he
remarks, " certainly no such concentration would be found
on the Cape Peninsula." I think it probable that the
" radius of a mile '' is meant a mile bevond the citv and
suburbs of Svdnev, in which case it mio'ht bo an area of
from 10 to 20 square miles. Or it might mean a picked
42 THE WORLD OF LIFE
area of about 4 square miles of uncultivated land some miles
away. That this latter is quite possible is shown by my
friend Mr. Henry Deane, who has for many years studied
the flora of 20 square miles of country around Hunter's Hill,
on the Paramatta Kiver, to the north-west of Sydney, and he
here obtained 59 species of Orchids out of a total of 618
flowering plants. The sequence of the first eight orders in
number of species is as follows : —
1. Orchidese 51)
2. Myrtaceae 5.5
3. Leguminosse 53
4. Pioteacese 35
5. Compositae 32
6. Graminese 31
7. Cyperacese 30
8. Epacridese 25
In XcAv South Wales, as a Avhole, Leguminosse are first
and Orchids fifth in order. There is probably no other
purely temperate flora in which Orchids so distinctly take
the first place as in the vicinity of Sydney.
The contrast in the numbers of species, in approximately
comparable areas, between these two groups of waiTQ-temperate
floras is fairly well marked throughout, there being, with few
exceptions, a decided preponderance in the southern hemis-
phere. South Africa is undoubtedly richer than China, though
its area is less ; and perhaps than the oriental region of Bois-
sier; Avhile Chili compares favourably with Japan or the West-
ern Himalayas. Still, the differences are not very pronounced,
and are such as appear due to their past history rather than to
any existing conditions. Those in the northern hemisphere
(except perhaps in the case of the Mediterranean coasts) have
probably been for a considerable period stationary or expand-
ing; while those in the south have almost certainly been far
more extensive, and in later geological time have been contrac-
ting, and thus crowding many species together, as already ex-
plained.
CHAPTER IV
TJIE TEOPICAL FLORAS OF THE WORLD
Although the idea of the tropics is always associated with
that of a grand develojiment of luxuriant vegetation, yet this
characteristic by no means applies to the whole of it, and
the inter-tropical zone presents almost as much diversity in
this respect as the temperate or even the frigid zones. This
diversity is due almost wholly to the unequal and even er-
ratic distribution of rainfall, and this again is dependent on
the winds, the ocean currents, and the distribution and ele-
vation of the great land masses of the earth.
Once a year at each tropic the sun at noon is vertical for
a longer period continuously tlian in any other latitude, and
this, combined with the more complex causes above referred
to, seems to have produced that more or less continuous belt of
deserts that occurs all round the globe in the vicinity of those
two lines, but often extending as far into the tropics as into
the temperate zone. In a few cases similar conditions occur
so near the equator as to be very difficult of explanation. It
will be instructive to review briefly these arid regions, since
they must have had considerable influence in determining
the character of the tropical vegetation in their vicinity.
Beginning with the Sahara, pre-eminently the great desert
of our globe, if we take it with its extension across Arabia,
we find that it occupies an area nearly equal to the whole
of Europe, and that the African portion extends as far to
the south as to the north of tlie tropic of Cancer. It thus
eats away, as it were, a great slice of what in other continents
is covered with tropical vegetation, and forms a vast barrier
separating the tropical and temperate floras, such as exists
43
44 THE WORLD OF LIFE
in no other part of the world. Passing eastward, the desert
regions of Baluchistan, Tibet, and Mongolia are situated
farther and farther north ; while abundant rainfalls and a
truly tropical vegetation extend far beyond the tropic into
what is geographically the temperate zone. This is especially
the case along the southern slopes of the Himalayas and their
extension into Burma and southern China.
In the western hemisphere we have the desert regions of
Utah, Arizona, and parts of northern Mexico all in the tem-
perate zone.
In the southern hemisphere the desert interior of central
and western Australia reproduces the Sahara on a smaller
scale. In Africa there is the Kalahari desert, mostly south
of the tropic, but on the west coast extending to about 15°
from the equator. In South America an arid belt of almost
complete desert extends along the coast from near the equator
to Coquimbo in Chili, whence crossing the Andes it stretches
south-eastward into Patagonia. Even more extraordinary is
the fact that in north-eastern Brazil, in the provinces of
Ceara, Pernambuco, and Bahia, are considerable areas which
have such small and uncertain rainfall as to be almost des-
erts, and are practically uninhabitable. And this occurs
only a few hundred miles beyond the great Amazonian forests
of Maranham in 3° S. latitude.
With the exception of these areas of very deficient rain-
fall, it will, I believe, be found that the intertropical regions
of the globe are the most productive in species of plants,
and, further, that as we approach the equator, where the
temperature becomes more uniform throughout the whole year
and the amount of rain and of atmospheric moisture is also
more evenly distributed, the variety of the species reaches
a maximum. There is some evidence to show that this is
the case not only in the region of the great forests, but also
in those less humid portions which are more or less open
country with a vegetation of scattered trees and shrubs, to-
gether with herbaceous and bulbous plants which cover the
i
TEOPICAL FLORAS
45
ground only during the season of periodical rains, as will be
shown later on.
Tropical Floras — Large Areas
Country.
British India
The Indian Peninsula
Burma
Indo-China
Malay Peninsula
Ceylon
Java
Philippines
New Guinea
Queensland
Tropical Africa south of-*
Sahara /
Madagascar and Mascarenes.
Central America and Mexico.
Nicaragua to Panama
Brazil
Trinidad ,
Jamaica
Area,
Square
Miles.
No. of
Species.
1,300,000
500,000
172,000
225,000
35,000
25,000
50,000
115,000
310,000
668,000
6,500,000
229,000
910,000
80,000
3,200,000
1,750
4,200
17,000
4,500
6,000
7,000
5,100
2,800
4,000?
4,656
6,000
4,454
18,300
5,950
12,000
3,000
22,800
1,967
2,720
Authority.
Sir J. D. Hooker
Hooker
Gagnepain
Gamble
Hooker
Koorders
Merrill
Lauterbach
Bailey
Thonner's Census
Thonner
Hemsley
Martius
Harti
Brittan
The Tropical Flora of Asia
As no part of the Asiatic continent (except the Malay
Peninsula) approaches within eight degrees of the equator, its
tropical area is very limited, barely reaching one and a quarter
million square miles; and even if we add to it the whole of
the Malay Archipelago, the Philippines, ^ew Guinea, and
tropical Australia, it will not much exceed two millions. Yet
these countries are in general so richly clothed with a tropical
vegetation, that the actual number of their species will almost
1 Mr. W, E. Broadway, who has collected in the island, informs me that
some hundreds of species remain to be discovered in Trinidad.
16 THE WORLD OF LIFE
certainly surpass those of Africa, with three times their
tropical area, and may approach, though I do not think they
will equal, those of tropical America, or even of tropical
South America only. Portions of this area have been well
explored, especially the great peninsulas forming India
proper, Burma, and Indo-China ; but the two latter are only
sufficiently known to show their extreme richness botanically,
and the same may be said of the numerous large islands of
^ the Malay Archipelago. We may, I think, be certain that
what is known of these two sub-regions is less than what re-
mains to be made known.
Sir Joseph Hooker estimates the whole flora of British.
India at 17,000 species, including the desert flora of the Indus
valley and the rich temperate and alpine floras of the
Himalayas above an elevation of 6500 feet in the east and
above 4000 or 5000 in the west. But as I am here dealing
with tropical floras, it is only necessary for me to give such
figures as are available for the specially tropical portions of
it.
The Indian Peninsula, bounded on the north by a curving
line of hills and mountains which run not far from the line
of the geographical tropic, is somewhat poor when compared
with the aboundino: riches of Burma and Indo-China; vet it
possesses areas, especially in the Western Ghats and the
Xiigiris, of great botanical richness and beauty, much of which
is still inadequately explored. Arid conditions prevail over
much of its surface, both in the north and in the central
plains, but these are interspersed w'ith deep moist valleys
containing a vegetation allied to that of Assam. As a result
of this greater aridity than that of the countries farther east,
the peninsula is much poorer in Orchids, having only 200
species against 700 in Burma ; but it has a great excess in
Grasses, L^mbellifer?e, Labiatj:Te, and Boragine?e, and a cor-
responding poverty in Melastomaceo?, Gesneracege, Myrtacese,
Palms, and other more peculiarly tropical orders.
Ceylon, though so closely connected with the peninsula, has
TKOPICAL FLORAS 47
a distinct flora, nearly 800 of its species and 23 of its genera
being '^ endemic/' that is, wholly peculiar to it. It has much
stronger affinities with the ]\ialayan flora, due in part, no
doubt, to its moister and more uniform insular climate, but
also to some features of its past history.
The figures given in the table of the chief tropical floras
of the world (p. 45) indicate, so far as possible, the actual
numbers of the species now existing in collections, and, for
purposes of comparison, require certain allowances to be
made.
Burma and Tndo-China are much less known than Penin-
sular India, vet in a smaller area each has a considerably laro;er
number of species ; while the Malay Peninsula, which is more
completely forest-clad, is in proportion to its area still richer,
due mainly to its more equable equatorial climate. The fol-
lowinc: table of the chief natural orders is taken from Mr.
Ilemsley's Introduction to the Flora of Mexico and Central
America : —
British Ixdia (17,000 species)
1. Orchidere 1060
2. I^giiiiiinosiE 831
3. Glramineoe 800
4. Robiacese 611
5. Euphoibiacese 624
6. Acanthaceae 503
7. Compositae 598
8. Cypeiaceaj 385
0. Labiatae 331
10. Urticaceae 305
11. Asclepiadeae 249
12. Rosaceae 218
The sequence of the orders is taken from Sir J. Hooker's
Sketch of the Flora of British India, a most interesting and
instructive pamphlet published in 1906, but the numbers of
species are inserted from Mr. Hemsley's work dated 1888.
Since then the total numbers have increased from 13,647 to
17,000, about one-fourth, so that the above figures will have
to be increased in that proportion ; but they will have increased
unequally, as shown by the fact that the orchids are estimated
by Sir. T. Hooker at 1600.
There is apparently no other extensive region as varied
in soil and climate as British India, in which Orchids occu]\v
the first place in the sequence of the orders. This is due to
48
THE WORLD OF LIFE
their great numbers in Burma, but even more to the fact
that in the whole range of the Himalayas epiphytic Orchids
extend far into the temperate zone, while in the more eastern
ranges they are pre-eminently abundant. This is well shown
by the well-explored district of Sikhim, in which Orchids take
the first place, not only in the tropical lowlands, but in the
temperate zone from 6500 to 11,500 feet above the sea-level.
It is possible that in some parts of the temperate Andes, wdiere
Orchids are known to be extremely plentiful, the same pro-
portion may exist ; but no such district appears to have been
yet sufficiently explored by botanists. Before going further
it will be as well to give the sequence of the orders in the
districts already referred to.
Tropical Sikhim (up to 6500 feet) (2000 species)
1. Orchideae (1)
2. Leguminosae (2)
3. Gramineae (3)
4. Urticacese (8)
5. Euphorbiaceae (5)
6. Cyperaceae (7)
7. Rubiacese (4)
8. Compositae (9)
9. Aselepiadeae
10. Acanthaceae (6)
The numbers enclosed in brackets give the sequence in
Burma, Avhich is very similar, except that Scitaminese (the
Gingerworts) is the tenth order, while Asclepiadese is ex-
cluded.
The Malay Peninsula differs still more from the flora of
north-eastern India, in being more exclusively equatorial and
typical Malayan, and in this case I am able, through the kind
assistance of Mr. J. T. Gamble, to give the number of species
for the first twelve orders, which will be interesting for com-
parison with others to be given further on.
Malay Peninsula (5138 species)
1. Orchidaceae 540
2. Rubiaceae 312
3. Leguminosae 266
4. Euphorbiaceae 255
5. Anonaceae 178
6. Palmae 163
Ferns
7. Lauraceae 153
8. Gramineae 144
9. Zingiberaceae (Scitamineae) 137
10. Gesneraceae 131
11. Acanthaceae 128
12. Cyperaceae 127
368 species.
Fig. 1. — Forest in Kelantan, jNIalay Peninsula.
TROPICAL FLORAS 49
This may be considered a typical Malayan flora of the low-
lands, the mountains not being sufficiently extensive or lofty
to favour the abundance of Composita' found in Sikhini and
Burma; while the Anonacese (custard apples); the Lauracege
(true laurels), producing cinnamon, cassia, and many other
sj^ecies and odoriferous nuts, barks, and fruits, and, above
all, the noble order of Palms, which have alwavs been con-
sidered the most characteristic of the vegetable productions of
the tropics, all take a higher place than in any part of India.
Sir Joseph Hooker estimates the known, palms of Burma at
68, so that it is hardly probable that any future additions
will bring them to an equality with the much smaller Malay
Peninsula. This affords another illustration of the increase
in the number of species of Palms as we approach the equator,
and renders them, with the Rubiacese, the Euphorbiacese, and
the Orchids, the most typical of equatorial orders of plants.
Through the kindness of Professor R. H. Yapp I am able
to give here two beautiful photographs taken by himself in
the Malayan forests, which give an excellent idea of the
general character of the vegetation, though unfortunately not
many of the trees or other plants shown can be identified;
but a few remarks may be made as to their general charao-
ter.
Very prominent on the large trunk in the foreground is
the bird's-nest fern (Asplenium nidus), very common in the
forests and also in our hot-houses. Above it is a climbing
fern (AcrosticJium scandens). On the left is a light-coloured
slender tree with knobs or spines, and having many climbers
about it. This may be a palm.
Among the tangled vegetation in every direction are slender
lines, upright, oblique, or beautifully curved; these are the
lianas or forest-ropes, many being rattans (palms), but others
belong to various dicotyledonous plants of many natural or-
ders; and these form one of the most constant and charac-
teristic features of the damp equatorial forests both in the
eastern and western hemispheres. The slender shrub to the
50 THE WOELD OF LIFE
left, with a spray of foliage showing light against the dark
trunk, may be an Ixora. On the left, crossing the spined
trunk, is one of the climbing palms or rotangs (commonly
called ^'rattan'' in England), while the dense mass of vege-
tation to the right is largely composed of slender bamboos.
The other view (Fig. 2) is more characteristic of the dense
Malayan forest, where trees of all sizes, climbers of many
kinds, and tangled undergrowth, of dwarf palms, shrubs, and
herbs, fill up every spot on which plants can obtain a foot-
ing. The large twisted climber in the foreground is perhaps
a Bauhinia (Leguminosse), thougli it may belong to any of
a variety of genera, and even orders, which form such ropes.
The distinct ribbed leaf showing to the left of the most
tw^isted part is probably one of the Melastomacege. The dwarf
palms in the foreground are also very characteristic. Just
above where the twisted climber goes out of sight is a climb-
ing fern (Acrostichum scandens), and it seems to grow on
a knobbed or spined trunk like the one in the other picture.
A close examination will show that the five or six trunks
of tall trees visible have each peculiarities of growth or of
bark which prove tbem to belong to quite distinct species.
The very straight one to the left of the rope-climber is a
palm. The abundance of climbers is shown by the numerous
very fine wdiite or black lines here and there crossing the
picture, especially in the lower portion, each representing a
liana or forest-cord striving to work its way upward to the
light. In the original photograph the tangled mass of foliage
in the foreground is seen to consist of a great variety of plants.
The fern with very narrow fronds at the base of the rope is
NepJu'oIejns cordifolia, while the large closely pinnate leaves
in the foreground, as well as the smaller ones, truncate at
the ends, are various species of palms. The prints, unfor-
tunately, do not show all the details in the original photo-
graphs.
Professor O. Beccari, in the interesting volume on his ex-
plorations in Borneo, tells us that when building a house
Fig 2. — Forest in Perak. ^fal.iv Pcniiisiiln.
TKOPICAL FLORAS 51
on tlie Mattang inuunUiiii in Sarawak, three straight trees,
each about 9 inches diameter, were found growing at such a
distance and position as to be exactly suitable for three of
the corner posts of the house in which he afterwards resided
during some months' collecting there. When the tops were
cut off, and he could examine them, he found them to be-
long to three different genera of two natural orders, and also
that they were all new species probably peculiar to Borneo.
Another illustration he gives of the great productiveness of
these forests in species of trees is, that in the two months
he lived in his forest home he obtained fifty species of
Dipterocarps (an order in which he was much, interested) in
two months' collecting and within a mile of his house. This
order of plants consists entirely of large forest-trees, and is
especially characteristic of the true Malay flora from the
Peninsula to Java, Celebes, and the Philippines. It is prob-
ably at its maximum in Borneo, as Professor Beccari gives
it as the twelfth in the sequence of orders as regards number
of species: (1) Rubiace^e; (2) Orchidace^, 200 species; (3)
Euphorbiaceee ; (4) Leguminosse; (5) Anonace^e; (6) Melas-
tomacene; (7) Palmse, 130 species; (8) Urticacese; (9)
Myrtacese; (10) Aracese; (11) Guttiferse; (12) Diptero-
carpe?e, 60 species. This list, it must be remembered, refers
to the '^ primeval forests " alone, taking no account of the
widespread tropical flora found in old clearings and in the
vicinity of towns and villages.
Before leaving the Asiatic continent I must say a few words
as to the figures given in the table for the plants of Indo-
China, comprising the whole territory between Buraia aud
China, which has been at least as w^ell explored by French
botanists as have Burma and the Malay Peninsula by our-
selves. Having been unable to obtain any statistical infor-
mation on this area from English botanists, I applied to ]\r.
Gagnepain, of the botanical department of the ^N^atural His-
tory Museum of Paris, who hns kindly furnished me witli
the following facts. They have at the Museum very large
62 ' THE WORLD OF LIFE
collections of 2)laiits from all parts of tliis territory, collected
from 1862 onwards, but great numbers of the species are
still undescribed. Only small portions of the Hora have been
actually described in works still in process of publication ; but,
from his knowledge of this extensive herbarium, he believes
that the flora of Indo-China, as actually collected, comprises
about 7000 species.
Flora of the Malay Islands
The great archipelago (usually termed the Malayan, or
^' Malaisia "), which extends from Sumatra to Xew Guinea,
a distance of nearly 4000 miles, and from the Philippines
to Timor, more than 1000 miles, comprises an actual land
area of 1,175,000 square miles, which is fully equal to that
of all tropical Asia, even if we include the lower slopes of
the Eastern Himalayas. Tliis great land-area has the advan-
tage over the continent of being mainly situated within ten
degrees on each side of the equator, and having all its coasts
bathed and interpenetrated by the heated waters of the Indian
and Pacific Oceans. These conditions have led to its being
almost wholly forest-clad, and to its possessing a flora com-
parable in luxuriance and beauty with that of the great
Amazonian plain, situated almost exactly at its antipodes.
The western half of this archipelago has undoubtedly
been united with the continent at a comparatively recent
geological epoch, and this portion of it, both in its animal
and vegetable life, is nearly related to that of the Malay
Peninsula and Siam ; but the three chief islands, Sumatra,
Borneo, and Java, are of such great extent, and have such,
differences, both of geological structure and of climate, as
to give to each of them a distinct individuality, combined
with, in all probability, a Avealth of species fully equal to
that of the adjacent continent.^ The remainder of the Archi-
1 The Director of Kew Gardens informs me that, in 1850, the flora of the (
" Netherlands India," extending from Sumatra to New Guinea but exclud-
ing the Philippines, was estimated by the Dutch botanists to possess 0118
TEOPICAL FLORAS 53
pelago has bad, however, a different origin, and has been
much longer isolated. Celebes and the Philippines have cer-
tain features in common, indicating a remote but partial union
with, or approximation to, the Asiatic continent, and probably
subsequent submergence to an extent that has greatly impov-
erished their mammalian fauna. Xew Guinea, however,
stands alone, not only as the largest island in the world (ex-
cluding Australia), but as, in some respects, the most remark-
able, both by its extraordinary length of about 1500 miles,
and its possession of a range of snow-capped and glaciated
mountains. Biologically it is unique by having produced the
wonderful paradise-birds, numbering about 50 species ; while
its true land-birds already known amount to about 800 species,
a number very far beyond tliat of any other island — Borneo,
with its almost continental fauna, having about 450, and the
great island-continent of Australia about 500.
But, as regards plant-life, this vast archipelago is much less
known than that of inter-tropical Asia, though it will, I believe,
ultimately prove to be even richer. Of the two larger w-estern
islands, Sumatra and Borneo, I can obtain no estimate of the
botanical riches, and the same is the case with the whole of
the Moluccas. Java is better known, but still inadequately.
There remains for consideration the Philippines, Celebes, and
^ew Guinea, as to which we have recent information of con-
siderable interest.
Since the Americans have established themselves in the
Philippines they have done much to make known its natural
products; and Mr. E. D. Merrill, botanist to the Bureau of
Science at Manilla, has greatly increased our former scanty
knowledge of its very interesting flora. He has been so kind
as to send me several of his published papers, as well as a
complete MS. list of the families and genera of vascular plants,
with the number of species known to inhabit the islands up to
species of flowering plants then known. As such large portions of all the
islands are almost unknown botanically, it seems not improbable that the
actual numbers may be three times as many.
54 THE WORLD OF LIFE
August 1909. This shows the large total of 4656 indigenous
flowering plants already collected, though extensive areas in all
the islands, and more especially in the great southern island
Mindanao, are altogether unexplored. Besides these, there are
no less than 791 ferns and their allies, a number which is
probably not surpassed in any other country of equal extent
and as imperfectly explored. The Malay Peninsula has rather
more flowering plants, but its ferns are only 368, as given in
]\rr. Eidley's list, issued in 1908. The following is the
sequence for the first twelve orders (excluding introduced
plants) from Mr. Merrill's lists: —
Philippixes (4G56 species)
1. Orchideffi 372
2. Eubiacese 267
3. Leguminosae 258
4. Euphorbiacese 227
5. Urticaceae, with ]\Ioraceae . . 221
G. Graminese 215
7. Cyperaceae 137'
8. Myrtaceae 105
9. Palmse 100
10. Asclepiadeae 94
11. Melastomaceae 86
12. Compositae 83
Ferns 791 species.
Comparing this with the Malay Peninsula (jd. 18), we find
the first four orders in similar places of the sequence, while
Anonacese, ScitamineiT, and Melastomacese give way to Myr-
tacese, Palma^, and Asclepiadeae.
The Philippine flora has a large proportion of its species
peculiar to it. In some families, such as the Ericaceae, Ges-
neracese, Pandanacese, etc., almost all are so. Among species
of limited range some interesting facts have been ascertained
by Mr. Merrill. Of identical or closely allied species in sur-
rounding countries, 39 have been found to extend to northern
India, 38 to China, and 21 to Formosa, while only 9 have been
noted in the nearer islands of Borneo, Java, and Sumatra.
But the most decided similarity is found between the Philip-
pines and Celebes, 76 species having been found either identical
or represented by allied species ; and, considering how very
imperfectly the Celebesian flora is known, the amount of simi-
larity may be expected to be really very much greater. A sim-
TEOPICAL PLOKAS 55
ilar relation of the mammals, birds, and insects of the two
island groups have been pointed out in my Island Life, and
leads to the conclusion that the islands have, at some distant
period, been almost or quite united.
The Flora of Celebes
Very little was known of the flora of this extremely inter-
esting island till 1898, wdien Dr. S. H. Koorders published a
large quarto volume of nearly 750 pages, giving the results of
his own collections during four months in the north-east pen-
insula (Minahasa) together with all that had been made known
by the few botanists who had previously visited the islands.
Dr. Koorders himself collected or examined 1571 species, of
which nearly 700 were trees ; and he has given lists of 468
species w-hich had been collected in various parts of the island
by other botanists, making a total of 2039 species of flowering
plants. The great peculiarity of the flora is indicated by the
fact that nineteen of the genera of trees are not kno^\Ti in
Java ; wdiile the affinities are, on the whole, more Asiatic than
Australian, as is the case with the animals. The closest affin-
ity is W'ith the Philippines, as with the birds and mammals,
as indicated by a new genus of trees (W allacesdendron celehi-
cwn), allied species having been since found in the adjacent
group. Dr. Koorders also remarks that some of the plants
have very peculiar forms, almost comparable with those I have
pointed out m its butterflies. One of these is no doubt the
new^ fig-tree (Ficus minaliassa) , a drawing of which forms the
frontispiece of this volume. It is about 40 feet high, the
fruits hanging thickly from the branches in strings 3 or 4 feet
long, giving it a very remarkable appearance. His general
result is, that the flora is very rich in peculiar species, but
rather poor in peculiar genera.
As this work is wholly in Dutch, I cannot give further
details, but having counted tlie species in each natural order
I will add a list of the ten largest orders for comparison with
others here given : —
56
THE WOELD OF LIFE
\
1. Urticaeese 158
2. Legviminosse 105
3. Rubiacese 103
4. Euphorbiaceae 100
5. Orchideae 81
6. Palmaeeae 78
7. Gramineae 71
8. Compositse 63
9. :\Iyrtaeea». 58
10. Meliaceae 58
I will add a few words on a point of special interest to
myself. Having fonnd that tlie birds and mammals of the
eastern half of the Archipelago Avere almost wholly different
from those in the western half, and that the change occurred
abrnptly on passing from Bali to Lombok, and from Borneo
to Celebes (as explained in chapter xiv. of my Malay Archi-
pelago), the late Professor Huxley proposed that the straits
between them should be called '' Wallace's Line," as it forms
the boundary between the Oriental and Australian regions.
But later, as stated in my Island Life, I came to the conclu-
sion that Celebes was really an outlier of the Asiatic continent
but separated at a much earlier date, and that therefore Wal-
lace's Line must be dra^vn east of Celebes and the Philippines.
The Flora of New Guinea
Early botanical explorers in Kew Guinea were disappointed
by finding the flora to be rather poor and monotonous. This
was the case with Prof. O. Beccari, who collected on the north-
w^est coast; and Mr. H. O. Forbes, of the Liverpool Museum,
informs me that he formed the same opinion so long as he had
collected on the lowlands near the coast, but that on reaching
a height of near 1000 feet a much richer and quite novel flora
was found. Prof. Beccari, who is at this time studying the
palms from various recent Dutch, British, and German collec-
tions, now thinks that the number of species in Xew Guinea
is probably as gTeat, in equal areas, as in Borneo or the Malay
Peninsula, but that the species are not so distinctly marked
as in those countries. Thev are what he terms second-ffrade
species as compared with the first-grade species of the latter.
But he forms this opinion chiefly from the palms, of which
he makes a special study.
TKOPICAL riOKAS 57.
Dr. Lauterbach, who is engaged in describing the new plant-
collections recently obtained, is evidently much impressed by
them. He states that down to 1905 there were known from
German Xew Guinea 2048 species of flowering plants, while
about 1000 additional species had been found in other parts
of the island. But the last Dutch expedition, from the por-
tions of the collections he has examined, will probably add
another 1000 species. Again he says that from collections
recently made by Schlechter in German Xew Guinea, and
through letters from him, an ^' immense increase in the number
of species is in prospect.'^ A few^ more years of such energetic
collecting will disclose more of the treasures of this the largest
of the great tropical islands, while its grand central chain of
mountains may be expected to produce a large amount of nov-
elty and beauty. Dr. Lauterbach's conclusion, in a letter to
Prof. Beccari, is as follows : " I believe, indeed, that one would
not estimate it too highly if one reckoned the sum total of the
Papuan Phanerogams at a round number of 10,000." Con-
sidering that ^ew Guinea has more than double the area of
the Philippines (which Mr. Merrill also estimates may con-
tain 10,000 species) ; that it is nine times the area of the
Malay Peninsula, which has already more than 5000 species
described; that it has the enormous length of 1500 miles, all
between 0° and 11° of S. latitude; that it has an extremely
varied outline ; that it possesses abundant diversity of hill and
valley, and a central range of mountains which have now been
proved to rise far above the line of perpetual snow ; and finally,
that it is almost everywhere clad with the most luxuriant for-
ests, and enjoys that moist and equable equatorial climate
which is proved to be most favourable to vegetable as well as
to insect life, it seems to me probable that it may ultimately
prove to be among the richest areas on the earth's surface. In
bird-life it seems likely to surpass any other equal area, and it
may do so in plants also, but In the luxuriance of insect-life
I am inclined to think that it will not equal the richest por-
tions of equatorial America.
68 THE WORLD OF LIFE
The only other tropical flora in the eastern hemisphere in-
cluded in my table is that of Queensland, which is mostly
within the tropics, but a large part of the interior consists of
elevated plains with a rather arid climate where little of the
luxuriance of tropical vegetation is to be met with. Probably
not more than one-fourth of the area is clothed with a typical
tropical vegetation, but this has as yet been very partially
explored botanically. The number of species compares best
with that of the Indian peninsula, with wdiich it agrees nearest
in area ; and both these countries, though very rich in certain
districts, cannot be considered to present examples of the full
luxuriance of tropical vegetation.
Floras of Tropical Africa and America
The floras of the remainder of the tropics are, for various
reasons, of less interest for the purposes of this work than
those of the eastern hemisphere, and a very brief reference to
them wdll be here given. Although Africa has a tropical area
nearly equalling those of Asia and America combined, it has a
flora of less extent and of less botanical interest than that
of either of them. Its area of luxuriant tropical forest is
comparatively of small extent, and much of it is yet unex-
plored, so that the number of species in the latest enumeration
is perhaps more than might have been expected. The islands
belonging to Africa — ■ Madagascar, Mauritius, Bourbon, and
the Seychelles — are, however, of extreme interest, on account
of the remarkable character, as well as the extreme speciality,
both of their plants and animals. As, however, these pecul-
iarities have been rather fully discussed in chapter xix. of my
Island Life, it is not necessary to repeat them here. I may
state, however, that in Mauritius there are about 40 peculiar
genera, nearly all of shrubs or trees, while no less than 5
peculiar genera of palms are found in the Seychelle Islands.
The following table of tlie sequence of orders in Madagascar
may be of interest for comparison with those of other large
floras.
TROPICAL FLOEAS 59
Madagascar (5000 species)
1. Leguminosae 346
2. Compositae 281
3. Euphorbiaceae 228
4. Orchideae 170
Ferns
5. Cyperaceae 160
6. Rubiaceaj 147
7. Acantluiceae 131
8. Giamineae 130
318 species.
The above table was made when the whole flora consisted
of 3740 known species. As it is now increased to nearly 5000,
the figures given will have to be increased by one-third on the
average. But as this increase may be very unequal, they have
been left as sriven.
Flora of Tropical America
We have seen reason to believe that the temj^erate flora of
^orth America is somewhat poorer than that of Europe and
northern Asia, though the south temperate zone as represented
by Chili is exceptionally rich. But there can be little doubt
that its whole tropical flora is extremely rich ; and it may not
improbably be found to contain nearly as many species of
plants as all the rest of the tropical world. This may per-
haps be indicated by the fact that it has fourteen or fifteen
natural orders quite peculiar to it, wdiile the remainder of the
globe has about the same number ; but, taking account of
three other orders that are almost exclusively American, Mr.
Hemsley is of opinion that the balance is on the side of
America.
America has the great advantage of possessing the largest
continuous or almost continuous extent of tropical forest on
the globe. The vast Amazonian plain forms its central mass
of about two millions of square miles of almost continuous
forest. From this there are northward extensions over the
Guianas and parts of Venezuela, along the north-east branch
of the Andes to Trinidad, and thence through Panama and
Honduras to the lowlands of eastern and western Mexico.
Southward it sends out numerous branches along the great
river valleys into central and western Brazil, and thence along
60 THE WORLD OF LIFE
the eastern slopes of the Andes to beyond tlie southern tropic;
while all along the Atlantic coast there is a belt of equal lux-
uriance, spreading out again in the extreme south of Brazil
and Paraguay to about 30° of south latitude. We could thus
travel continuously for about five thousand miles from Mexico
to northern Argentina in an almost unbroken tropical forest,
or about the same distance down the Amazon valley to Par-
anahyba in northern Brazil, and then, after a break of a few
hundred miles, along the east coast forests for about two thou-
sand miles more. This probably equals, if it does not surpass,
the tropical forest area of the rest of the globe.
We must also take into account the fact that, as a rule,
tropical forests differ from those of the temperate zone in the
s^^ecies not being gregarious, but so intermingled that adjacent
trees are generally of distinct species, while individuals of the
same species are more or less widely scattered. When, from
some commanding elevation, we can look over a great extent
of such a forest, we can usually see, at considerable intervals,
a few, perhaps a dozen or more, small patches of identical
colour, each indicating a single tree of some particular species
which is then in flow^er. A few^ days later we see a different
colour, also thinly scattered; but in the region of the most
luxuriant tropical forests we never see miles of country thickly
dotted with one colour, as would often be the case if our Euro-
pean oaks or beeches, birches or pines, produced bright-col-
oured flowers. This fact would alone indicate that the tropical
forests are wonderfully productive in species of trees and woody
climbers, and hardly less so in shrubs of moderate size, which
either live under the shade of the loftier trees or line the banks
of every river, stream, or brooklet, or other opening to which
the sun can penetrate. In those latter positions there is also
no lack of herbaceous plants, so that the whole flora is exceed-
ingly rich, and the species composing it rapidly change in
response to the slightest change of conditions.
The difficulty of collecting and preserving plants in these
forest-clad areas is so great, and the number of resident bot-
TEOPICAL FLORAS 61
anists who alone could adequately cope with the work is com-
paratively so small, that it is not surprising to find thai the
great forest region of tropical America is still very imperfectly
known. Only tw^o considerable areas have been systematically
collected and studied — in ^orth America the entire tropical
portion from South Mexico to Panama commonly known as
'" Central America " ; and in South America the vast areas of
Brazil, itself comprising more than half of tropical South
America. The comparatively easy access to this latter country,
the attraction of its gold and diamond mines, its extensive
trade with England and with other civilised countries, have
all led to its being explored by a long series of botanists and
travellers, the result of whose labours have been incorporated
in a moniimental work, the Flora Brasiliensis of Martins, re-
cently completed after more than half a century of continuous
labour.
The number of species described in this work is 22,800, an
enormous figure considering that its area is less than half that
of tropical Africa, and that probably two-thirds of its surface
has never been thoroughly examined by a botanist. The Cen-
tral American flora, as described by Mr. Hemsley,^ in less
than one-third of the area of Brazil has about 12,000 species,
and this is no doubt a much nearer approach to its actual num-
bers than in the case of Brazil.
As regards the additions that may yet be made to that flora,
and especially to the great forest region of adjacent countries,
I will quote the opinion of a very competent authority, the late
Dr. Bichard Spruce, who assiduously studied the flora of the
Amazon valley and the Andes for fourteen years, and himself
collected about 8000 species of flowering plants, a large pro-
portion of which were forest-trees. In a letter to Mr. Bentham
from Ambato (Ecuador), dated 22nd June 1858, he writes: " I
have lately been calculating the number of species that yet
remain to be discovered in the great Amazonian forest from
1 See Biologia Centrali Americana, by Messrs. Godman and Salveri;
Botany, 4 vols., 1888.
62 THE WORLD OF LIFE
the cataracts of the Orinoco to the mountaius of Matto Grosso.
Taking the fact that by moving away a degree of latitude or
longitude I found about half the plants different as a basis,
and considering what very narrow strips have up to this day
been actually explored, and that often very inadequately, by
Humboldt, Martins, myself, and others, there should still
remain some 50,000 or even 80,000 species undiscovered. To
any one but me and yourself, this estimation will appear most
extravagant, for even Martins (if I recollect rightly) emits
an opinion that the forests of the Amazon contain but few
species. But allowing even a greater repetition of species than
I have ever encountered, there cannot remain less than at least
half the above number of species undiscovered." ^
Spruce was one of the most careful and thoughtful of writers,
and would never have made such a statement without full con-
sideration and after weighing all the probabilities. In the
same letter he describes how, when leaving the Uaupes River
after nine months of assiduous collecting there in a very lim-
ited area, a sunny day after continuous rains brought out'
numerous flowers, so that as he floated down the stream he
saw numbers of species quite new to him, till the sight became
so painful that he closed his eyes to avoid seeing the floral
treasures he was obliged to leave ungathered ! At Tarapoto
he observed that some flowers opened after sunset and dropped
off at daAvn, so that they would be overlooked by most collectors,
while of many the flowering season was very limited, sometimes
to a single day. Join to this the scarcity of individuals of
many species scattered through a trackless forest, and it is evi-
dent that the true floral riches of these countries will not be
fully appreciated till numerous resident botanists are spread
over the entire area.
From the facts of distribution given by Mr. Hemsley we
learn that about one-twelfth of the species of Central America
1 See Spruce's Xotes of a Botanist on the Amazon and Andes, vol. ii. p.
208.
TEOPICAL FLORAS 63
are found also in South America, and that about TOO are found
in the eastern portion from Venezuela to Brazil, so that prob-
ably not more than 500 reach the latter country. The com-
bined floras of Brazil and Central America, even as now
imperfectly loiown, will therefore reach about 34,300 species.
N^ow, considering how very rich the eastern slopes of the Andes
are known to be, and that the average width of the forest zone
between Brazil and the Andes is from 400 to 500 miles, while
the plateaux and western slopes also have a rich and distinct
flora and fauna, I think it will be admitted, that whatever the
combined floras of Brazil and Central America may amount
to, that number will be nearly or quite doubled when the entire
floras of Venezuela, the Guianas, Colombia, Ecuador, and Peru
are thoroughly explored. As, roughly speaking, Brazil con-
tains about half the great tropical forests of South America,
and allowing that its portion is the best kno^vn, we may fairly
add one-third of Spruce's lower estimate (25,000) to its
present numbers, Avhich will bring the whole to very nearly
40,000 sjDecies. By doubling this, we shall reach 80,000 as
the probable number of species existing in tropical South
America.
As this number is considerably more than half the latest
estimate of the number of flowering plants yet known in the
whole world (136,000 species),^ more than half of which
number will be absorbed by the comparatively well-known tem-
perate floras, it will be apparent that we have at present a very
inadequate idea of the riches of the tropical regions in vege-
table life. This result will be further enforced by additional
facts to be adduced later.
I will here give a table of the few known statistics for trop-
ical America, which, though very fragmentary, will serve to
show the basis on which the preceding estimate of probable
numbers rests.
1 This number has been given me by Mr. W. B. Hemsley, Keeper of the
Kew Herbarium, as being that of Dr. Tlionner in 1008.
64
THE WORLD Or LIFE
Floras of Tropical America
Country.
Area,
Sq. Miles.
De
scribed
Species.
Remarks.
Mexico (8.) and Cen- 1
tral America J
Brazil
910,000
3,200,000
79,000
4,200
1,750
2,400
12,000
22,800
3,000
2,722
1,967
445
Hemsley, 1888
Martins
Nicaragua to Panama ....
Jamaica
Hemsley
L. N. Brittan, 1909
Trinidad
J. H. Hart, 1908
CralaDasros
(1902)
Note. — The number of Trinidad plants is from a Herbarium
List by Mr. J. H. Hart, F.L.S., Superintendent of the Botanical
Gardens, published in 1908. He states, however, that "a large
amount of material has not been arranged under natural orders "
and that "the later added specimens have not been arranged for
several years past." But he adds, " As it now stands, there is
a good representation of the Trinidad flora."
Mr. W. B. Broadway of Tobago, who has lived several years in
Trinidad and has studied its flora, informs me that from his own
observation he believes that many hundreds of additional species
remain to be collected; and this is what we should expect, as the
island is a continental one ; while Jamaica, though larger, is almost
oceanic in character, and is therefore almost certain to have a less
complete representation of the tropical American flora than the
former island.
The great work on the flora of Mexico and Central America
deals, unfortunately for my present purpose, with an area in
which temperate and tropical, arid and humid conditions are
intermingled to a greater extent even than in the case of
British India already referred to. Mexico itself comprises
about four-fifths of the whole area, and nearly half its surface
is north of the tropic and is largely composed of lofty plateaux
and mountains. It thus supports a vegetation of a generally
warm-temperate but rather arid type; and these same condi-
tions with a similar flora, also prevail over the great plateau
of southern Mexico. This type of vegetation extends even
TEOPICAL FLORAS 65
farther south into the uphuuls of (liiateinala, so that we only
get a wholly tropical flora in the small southern section of the
area from Kicaragua to Panama.
The following table of the twelve largest orders in the whole
flora Avill be of interest to compare with that of British India;
Mexico and Central America (11,688 species)
1. Compositse 1518
2. Leguminosae 944
3. Orchidese 938
4. Gramineae 520
5. Cactaceae 500
6. Rubiaceae 385
7. Eiiphorbiacese 368
8. Labiata? 250
9. Solanaceae 230
10. Cyperaceae 218
1 1. Piperaeese 214
12. Malvaceae 182
Ferns 545
The most remarkable feature in this table is the great pre-
ponderance of Compositse characteristic of all the temperate
and alpine floras of America, and the presence of Cactaceae,
Solanaceae, Piperaeese, and Malvaceae among the 12 predomi-
nant orders, the first of the four being confined to America.
It may be noted that of the 12 most abundant orders 8 are
the same in these two very widely separated parts of the earth.
But even this table greatly exaggerates the actual difference
between the two very distinct floras. There are 175 natural
orders in British India, and of these only 20 are absent from
the Mexican region. Of these 20 orders 18 have less than 10
species (5 of them having only 1 species), so that, judging
from the great types of plants, the difference is wonderfully
small. We can therefore understand Sir Joseph Hooker's
view, that there are only two primary geographical divisions of
the vegetable kingdom, a tropical and a temperate region.
It must be remembered, however, that even when the series
of orders in two remote areas are nearlv identical, there mav
be a very marked difference between their floras. Orders that
are very abundant in one area may be very scarce in the other ;
and even when several orders are almost equally abundant in
both, the tribes and genera may be so distinct in form and
structure as to give a very marked character to the flora in
66 THE WORLD OF LIFE
which they abound. Thus the Urticacese include not only
nettles, hops, and allied plants, but mulberries, figs, and bread-
fruit trees. Even Avith so much identity in the natural orders,
there is often a striking dissimilarity in the plants of distinct
or remote areas, owing to the fact that the genera are very
largely different, and that these often have a very distinct
facies in leaf and flower. Thus, though the Myrtacese are
found in hot or warm countries all over the world, the Euca-
lypti, so abundant in Australia, give to its vegetation a highly
peculiar character. So the Onagracese are found in all the
temperate regions, yet the Fuchsias of South-temperate
America are strikinoly different from the Willow-herbs of
CD «-
Europe or the CEnotheras of ^^Torth America ; and there are
thousands of equally characteristic genera in all parts of the
world.
In Mr. Hemsley's elaborate table of the General Distribution
of Vascular Plants, he gives, in Central America, the number
of species of each order in Nicaragua, Costa Rica, and Panama
respectively, these three states constituting the tropical section
of the whole area, and the same for six subdivisions of the rest
of the area. But the numbers added together will give more
than the actual number of species in the combined flora, be-
cause an unlvnown portion of the species will be found in two
or three of these divisions. But he gives the total numbers
for these three states and also for the remainder of the nine
areas. He also gives the numbers which are '^ endemic " in
these two groups of areas separately and in the whole flora ; I
have therefore been able to ascertain the proportion which the
endemic bear to the total in Mexico and Guatemala, which I
find to be as 3 to 4 verv^ nearly, so that by deducting one-fourth
of the sum of the species in these areas I obtain the number
existing in the combined area. But as it is known that in the
tropics species have a less range than in the temperate zone,
I deduct one-fifth in the case of the three tropical areas, which
will, I believe, approach very nearly to the actual number of
species in the combined floras as given in the following table.
TEOPICAL FLOEAS 67
Nicaragua, Costa Kica, and Panama (3000 species)
1. Orchidcai 280
2. Conipositu? 107
o. LegLiiniiiQsaj 17(3
4. Riibiaeete 14(5
5. Uraminetp iH)
6. Eiiphoibiacese 72
7. Gesneraceaj GO
8. Cyperawa? 08
0. Alelastomacea^ 07
10. Urticacoai 58
11. Aioideie 5-t
12. Palraai 50
Ferns 252
This table brings out clearly the extra-tropical character of
Mexico as compared with these tro|)ical sections of Central
America. Xo less than five orders of the former twelve have to
be omitted (Cactacea?, Labiates, Solanacese, Piperaceas, and Mal-
vaceae), which are replaced by the more exclusively tropical Ges-
neracea?, Melastomacese, Urticacese, xVroideae, and Palmte.
Here, in two adjacent areas differing about 12° in mean lati-
tude, there is a more pronounced difference in the prevalent
orders of plants than exists between two great regions on oppo-
site sides of the globe. Another characteristic tropical feature
is seen in the large number of ferns, which are nearly one-
half those of the whole number found in Mexico and Central
America, which has an area nine times as great.
Of the other tropical American floras little need be said.
Jamaica and Trinidad are the onlv West Indian islands of
the larger group for which I have been able to get recent
figures. Mr. L. ]^. Brittan, of the ]^ew York Botanical Gar-
dens, who has collected in the former island, estimates the
species at 2722, which, for a sub-oceanic island, is a large
amount. Trinidad, which is almost a part of the continent,
should be much richer, and its existing collections, not quite
reaching 2000, are certainly much below its actual number
of species. The Galapagos, now probably fairly well known,
but possessing only 445 species, show us how scanty may be
the flora of a group of islands of considerable size and situated
on the equator, when the conditions are not favourable for
plant-immigration or for the gTowth of plants at or near the
sea-level, as has been pointed out in my Island Life.
Q8 THE WOKLD OF LIFE
The Flora of Lagoa Santa
There is, however, one small area in the Campos of Brazil
in about 20° S. lat. and 2700 feet above the sea-level, which
has been thoroughly explored botanically bv a Danish botanist,
Professor Eug. Warming, who lived there for three years with
his fellow-countrvman Dr. Lnnd, who first studied the fossil
vertebrates in the caves of the district. This was in 1SG3-66;
and after studying his collections for twenty-five years with the
assistance of many other botanists he published in 1892 a
quarto volume giving a most careful account of the vegetation
in all its aspects, with numerous very characteristic illustra-
tions, both of individual plants and of scenery, forming one
of the most interesting botanical works I have met with. Un-
fortunately it is printed in Danish, but a good abstract (about
thirty pages) in French renders it accessible to a much larger
body of readers.
This flora is strictly limited to an area of sixty-six square
miles, so that every part of it could be easily explored on foot,
and again and again visited as different species came into
flower or ripened their fruit. The surface is undulating and
in parts hilly, with a lake, a river, some low rocky hills,
marshes, and numerous deeply eroded ravines and valleys, often
with perpendicular rocky sides, where there is perpetual mois-
ture and a rich forest-vegetation. But everywhere else is for
half the year arid and sun-baked, covered with scattered decid-
uous trees and shrubs, and during the rains producing a fairly
rich herbaceous vegetation. It is, in fact, a good example
of the campos that occupy such a large portion of the interior
of Brazil, though perhaps above the average in productiveness.
An open country such as this is, of course, much easier to
examine thoroughly than a continuous forest, which, though
actually richer, calls for a much longer period of exploration
before all its riches can be discovered. But though the coun-
try is so open, with trees and shrubs spread over it in a park-
like manner, Mr. Warming tells us that trees of the same spe-
TROPICAL FLORAS
69
cies are so widely scattered that it is sometimes difficult to
find two of the same kind. Another interesting fact is, that
the number of species of all kinds — trees, shrubs, and herbs —
ei
(JJ CO
00
c3
O
fcD
bD
d (VI
Q
•*-> to
^ 2
B
o
CO ^*^
6 ^
M
is twice as great in the patches of forest as in the open campos,
while the two are so distinct that he believes them to have
hardly a species in common.
TO THE WORLD OF LIFE
Through the kindness of Professor "Warming I am able to
reproduce here a few of his characteristic drawings and photo-
graphs, with descriptions furnished by himself. These offer
a striking contrast to the photographs of typical Malayan vege-
tation at pp. 48 and 50.
As shewn in the view on p. 69 (Fig. 3) the vegetation cov-
ering the hills is w^hat is termed ^^ cam2:)os limpos," consisting
Fig. 4. — The Campo Cerrado; Lapa Vermelha Rocks to the Right.
of grasses and herbs with small shrubs, but with few trees
scattered in the grass-land. These trees are low, the stems
and branches tortnons or twisted. In the valleys where the
soil is richer in hnmus and always moist, there is thick forest.
TEOPICAL FLOKAS
71
The soil in all the campos is red clay. In the distance is seen
the smoke of fires on the campos. In the foreground is a
'' campo cerrado," i.e. a campo with many trees, but never so
close that the sun does not shine on the dense carpet of high
grasses and herbs under the trees ; which latter belong mostly
to the Leguminosge, Ternstromiacese, Vochysiacese, Anonacese,
Bignoniacese, etc.
Fig. 4 is a view taken in the " Campo cerrado," showing the
stunted form of the trees which characterise it. In the back-
ground are calcareous cliffs, in which are the fossil-producing
caves. At the foot of the cliffs the trees are closer and higher ;
and on the top is a more open and dry forest, each kind of
forest having its peculiar species of trees.
Fig. 5 (facing p. 72) is a view taken close to the rocks.
The upper branches of Mimosas and other trees are shown,
which grow at the foot of the cliffs, one of them being a tree
of the custard-apple family, whose branches are fruit-laden.
Numerous tall cactuses (Cereus ccerulescens) are seen growing
up from the rock itself, and several stinging and thorny plants.
Other genera growing on the rocks are Opuntia, Pereskia,
Peperomia, Epidendrum, Tradescantia, Gloxinia, Amaryllis,
Bomarea, Griffinia, and many others, so that we have here a
curious mixture of forest trees and climbers with moisture-
loving plants and those characteristic of arid conditions, all
growing close together if not actually intermingled.
Before describing a few of the special peculiarities of the
campo vegetation of Lagoa Santa, I will here give some numer-
ical data of interest to botanical readers. The sequence of the
orders in this very interesting flora is as follows : —
Lagoa Santa (2490 species)
1. Compositae 26G
2. Leguminosae 235
3. Gramineae 158
4. Orchidaceae 120
5. Euphorbiaceae 100
6. Myrtacese 100
7. Rubiaceae 94
8. Cyperaceae 77
0. Malpighiaceap 04
10. INIelastomaceae 62
1 1. Labiatae 49
12. AsclepiadeiB 48
Ferns and allies 106 species.
72 THE WORLD OF LIFE
The chief feature which distinguishes this flora from that of
Nicaragua and Costa Rica is the presence in some abundance
of the highly characteristic South ximerican order Malpighia-
cese, the high position of Myrtacese, with Labiates and Ascle-
piads in place of Aroids and Palms. Of the rather numerous
Orchids about 70 are terrestrial, 50 epiphytes. There are over
40 genera, of which Spiranthes has 16 species, Habenaria 12,
while 22 have only 1 species each. The very large American
genus Oncidium has only 5 species, while the grand genus
Cattleya, so abundant in many parts of Brazil, seems to be
entirely absent.
Adaptations to Brought
The plant figured on the next page, like many others of the
campos, has its roots swollen and woody, forming a store of
water and food to enable it to withstand the effects of drought
and of the campo-fires. The old stems show where they have
been burnt off, and the figures of many other plants with woody
roots or tubers, figured by Mr. Warming, show similar effects
of burning.
Still more remarkable is the tree figured on p. 74 (Fig. 7),
which is adapted to the same conditions in a quite different
way, as are many other quite unrelated species.-^ The group
of plants is really an underground tree, and not merely dwarf
shrubs as they at first appear to be. What look like surface-
roots are really the branches of a tree the trunk of which, and
often a large part of the limbs and branches, are buried in
the earth. The stems shown are the root-like branches, which
are 4—5 inches diameter, w^hile the growing shoots are from
2 to 3 feet high. The whole plan (or tree) is from 30 to 40
feet diameter. As the branches approach the centre they de-
1 The following species have a similar mode of gro\vth : Anacardium
Jiumile, Hortia Brasiliensis (Riitacese), Cochlospermum insigne (Cistaceae),
Simaha Warniingiana (Simariibaeese) , Erythroxylon campestre (Erythroxy-
laceae), Plumiera Warmingii ( Apocynaceae ) , Palicourea rigida (Cincho-
naceae ) , etc.
r.
a
o
O)
>
fie
o
c3
fcX)
P-
fcJO
o
o
c
o
ir^
TROPICAL FLOEAS
73
Fig. 6. — Casselia Chamcedrifolia, nat. size (Verbenacefie) .
scend into the earth and form a central trunk. A French
botanist, M. Emm. Liais, says of this species: " If we dig we
74
THE WORLD OF LIFE
find liow all these small shrubs, apparently distinct, are joined
together underground and form the extremities of the branches
of a large subterranean tree which at length unite to form a
single trunk. M. Eenault of Barbacena told me that he had
Fig. 7. — Andira Laurifolia (Papilionacese).
dug about 20 feet deep to obtain one of these trunks." The
large subterranean trees with a trunk hidden in the soil form
one of the most singular features of the flora of these campos
of Central Brazil.
The above facts are from Mr. Warming's book, supplemented
by some details in a letter. They are certainly very remark-
able ; and it is difficult to understand how this mode of growth
has been acquired, or how the seeds get so deep into the
ground as to form a subterranean trunk. But perhaps the
cracks in the dry season explain this.
A large part of these campos is burnt every year at the end
of the dry season, but as the vegetation is scanty the fires pass
TKOPICAL FLORAS T5
quickly onwards and do not appear to kill or injure the trees
or even the small herbaceous plants. In fact, numbers of
these plants as soon as the rains come produce foliage earlier
than Avhere there has been no fire, and often produce flowers
when unburnt trees or shrubs of the same species remain
flowerless. Mr. Warming and otlier botanists believe that the
practice of firing the campos was a native one long before the
European occupation, and that many of the plants have become
adapted to this annual burning so as to benefit by it.
It is interesting to note here the opinions of two eminent
botanists, only thirty years ago, as to the comparative riches
of certain tropical and temperate countries. In his great work
on The Vegetation of the Globe, Griesbach thus refers to the
Brazilian flora : ^^ The results of the explorations of Martins,
Burchell, and Gardiner, cannot be compared with those fur-
nished by the Cape. The number of endemic species may per-
haps reach 10,000, but the area is twenty times greater than
that of Cape Colony, and we may conclude that, as regards its
botanical riches, the Brazilian flora is very far from rivalling
that of the extremity of South Africa." Gardiner, however,
after spending three years in collecting over a large portion
of the interior of Brazil, though chiefly in the campos and
mountain ranges, concludes his account of his travels with these
w^ords : " The countrv is beautiful, and richer than anv other
in the world in plants." This general statement may not be
strictly true, but it seems clear that the facts already adduced
are sufficient to show that, as regards the comparison of tem-
perate with tropical floras, there can be no doubt as to the
superiority of the latter. This point will, I think, l)e made
still clearer in the following discussion of some almost unno-
ticed facts. In the case of Brazil and Cape Colony, however,
it is clear that Griesbach was creatlv in error. Tlie wliole
area of extra-tropical South Africa has probably been as well
explored botanically as Brazil, the richest portions of which
have been only as it were sampled. Yet wo find less than
14,000 species in the former against 22,S00 in the latter. It
76 THE WOELD OF LIFE
will be now shown that when smaller and better known areas
are compared the superiority of the tropics is more clearly
apparent.
The Floras of Small Areas and their Teachings
The conclusions already reached by the examination of the
chief floras of the world, whether in areas of continental extent,
or in those more approaching to the average of our counties,
that, other things being equal or approximately so, the tropics
are far more prolific in species, will receive further confirma-
tion, and I think demonstration, from data I have collected
as to the botanical richness of much smaller areas, which having
been more thoroughly explored afford more reliable evidence.
They also afford very suggestive facts as to the best mode of
future exploration which may enable us to arrive at a fair
approximation as to the total world-population of flowering
plants.
For the convenience of readers I give here two tables I
have prepared of the floras of small areas in tropical and tem-
perate zones, each arranged in the order of their area in square
miles for convenience of reference and comparison.
I will now briefly discuss the various interesting questions
raised by a consideration of these tables.
It is, I believe, still a very common opinion among botanists
that the wonderfully diversified flora of the Cape Region of
South Africa is the richest in the whole world in so limited
an area. This is partly owing to the fact that such a large
proportion are beautiful garden plants, which for sixty years,
from 1775 to 1835, j^oured in a continued stream into Europe
and seemed almost inexhaustible. The wonderful group of
heaths, of which there are about 350 species, all beautiful and
many among the most exquisite of flowers ; the almost equally
numerous pelargoniums, the brilliant ixias, gladioli and allies,
the gorgeous proteas, the w^onderful silver-tree, the splendid
lilies and curious orchises, the endless variety of leguminous
shrubs, and the composites including the everlasting flowers.
TEOPICAL FLORAS
77
Tropical Floras — Small Areas
Place.
1
2
3
4
5
6
Malacca
Singapore
Penang
Lagoa Santa, Brazil
Mount Pangerango, Java
Kambangan Island, Java
Area.
Species.
660
2000
206
1740
107
1813
66
2488
n
1750
n
2400
Authoritj'.
Gamble.
Ridley.
Curtis.
Warming.
Koorders.
Koorders.
Temperate Floras — Smalt. Areas
1
2
3
4
5
6
7
8
9
10
Place.
Mount Nikko, Japan ....
Cape Peninsula
Schaffhausen
Washington, D.C
Hertford ( near )
Paramatta River, Sydney
Capri, Italy
Edmondsham, Dorset
Cadney, Lines
Tliames Ditton
Area.
Species.
360
800
180
1750
114
1020
108
922
80
810
20
620
4
719
3
640
3
720
1
400
Authority,
Havati.
Bolus.
A. de Candolle.
Ward.
A. de Candolle.
H. Deane.
Beguinot.
Rev. E. F. Linton.
Rev. Woodruffe-Peacock.
H. C. Watson.
together with hundreds of other delicate and beautiful little
greenhouse plants, — formed an assemblage which no other
country could approach. Rich as it is, however, there is now
reason to believe that West Australia — Swan River Colony
in its original restricted sense — is quite as productive in spe-
cies, while evidence is slowly accumulating that many parts
of the tropics are really still more productive.
The first to be noticed of these rich tropical areas of small
extent is the island of Penang in the Straits of Malacca, which,
though only 106 square miles in area, contains 1813 species.
Sir Joseph D. Hooker, in his Sketch of the Flora of British
India (1906), terms this " an astonishing number of species,"
and remarks on the large proportion which are arboreous, and
of the altitude of the island being only 2750 feet. TTere, there-
78 THE WOKLD OF LIFE
fore, in an area considerably less than that of the Cape Pen-
insula, the species are actually more numerous, and this was
evidently a new and astonishing fact to one of the greatest of
our living botanists.
But the somewhat larger island of Singapore shows us that
this amount of productiveness is quite normal; for though it is
206 square miles in extent, it is almost flat, the greatest eleva-
tion being only a few hundred feet. A large part of the sur-
face is occupied by the town and suburbs, while the original
forest that covered it has been almost all destroved. Yet Mr.
Ridley finds it to have recently contained 1740 species, and
when the town was founded and the forest untouched, it almost
certainly had 2000 or even more.
We have seen also that Lagoa Santa in South Brazil,
2700 feet above sea-level, with a much smaller area than
Penang, and a much less favourable climate, has one-third
more species, mainly collected by one enthusiastic botanist
during three years' work in this limited district. Here are no
mountains, the whole country being an undulating plateau,
while for six months there is so little rain that the trees
almost all lose their leaves. The aridity causes the trees to
be mostly stunted and unshapely; the leaves are clothed on
one or both surfaces with felt or dense hairs; and the stems
of herbaceous plants are often swollen into thick tubers
either underground or just above it. There is thus a mani-
fest struggle for existence ajrainst the summer drought with
intense sun-heat, and it would hardly be imagined that under
such conditions the number of species would equal or exceed
that of some of the most luxuriant parts of the tropics.
I will now pass on to a consideration of the two last
items in the table of small tropical floras, which are more
instructive and even amazing than any I have met with in
the course of this inquiry. "\^^ien I was in Java about fifty
years ago I ascended the celebrated mountains Gede and
Pangerango, the former an active, and the latter, much the
higher, an extinct volcano. The two, however, form one
TROPICAL FLORAS T9
mountain with two summits. During the ascent I was much
impressed by the extreme hixuriance of the forest-growth, and
especially of the undergrowth of ferns and herbaceous plants.
I was told by the gardener in charge of the nursery of
cinchonas and other plants, that 300 species of ferns had been
found on this mountain, and I think 500 orchids. I was
therefore anxious to learn if any figures for the plants of
the whole mountain could be obtained, and was advised by
the Director of Kew Gardens to apply to Dr. S. Koorders of
the Reijks Museum, Leiden. In reply to my inquiries, Dr.
Koorders wrote me as follows : —
"The botanical mountain-reserve on the Gede (Pangerango) is
indeed very interesting and very rich, but I know other parts of
Java with a much larger number of phanerogams, e. g., the small
island of Xoesa Kambangan near Tjilatjap. On that island I
collected on an area of about 3 square kilometres (= 1% square
mile) 600 of arborescent species of phanerogams, and about 1800
species of not-arborescent species. This island is about 0 — 50 m.
altitude (=164 feet).''
" On Mount Pangerango, between 5350 feet and the top, 10,000
feet, the number of forest-trees is about 350 species on the same
area, and about 1400 species of not-arborescent phanerogams."
On reading the above, I thought at first that Dr. Koorders
must have made a mistake, and have meant to write 30 in-
stead of 3 square kilometres. So I wrote to him again ask-
ing for some further information, and pointing out that
Kambangan Island was many times larger than the area he
had given. To this he replied that he " only explored a small
part methodically," and that the number of species he gave
me '^ were found in that part only." ^ It thus became clear
1 It may seem to some readers, as it did at first to myself, that it is im-
possible to have over two thousand species of flowering plants growing
naturally on about a square mile. But a little consideration will show
that it is by no means so extraordinary as it seems. Let us suppose that
the average distance apart of trees in an equatorial forest is ten yards,
which I think is much more than the average; then in a square mile there
will be 176 X 170 = 30,976 trees. But in Kambangan Island there are 600
80 THE WORLD OF LIFE
that no mistake had been made. I was further satisfied of
this bj referring to a small volume by M. Jean Massart, en-
titled Un Botaniste en Malaisie. He there describes the
^' mountain reserA'e " on Pangerango as being 300 hectares of
virgin forest, extending from the limits of cultivation to near
the summit. As '' 300 hectares " is the same area as '' 3
square kilometres/' there can be no doubt as to the figures
given. M. Massart also states that Dr. Koorders was head
of the " forest-fiora " department of the Buitenzorg Botanical
Gardens, and that he had established eighteen other reserves
in various regions of Java. Each of these reserves is under
a native superintendent, who allows no tree to be cut down
without orders, and watches for the flowering and fruiting of
every species of tree. One specimen at least of all the species
is numbered, and paths made and kept in order, so that they
can be easily visited, and the flowers or fruit gathered for the
herbarium. Dr. Koorders has now obtained specimens of
about 1200 trees indigenous to Java, while 3500 specimens
have been numbered in the reserves. This number is without
counting either shrubs or climbers.
I give here a reproduction of a charming little photo-
graph taken in West Java more than fifty years ago by my
friend, the late Walter Woodbury, and I believe in the south-
ern country not very far from the island which Dr. Koorders
found so rich (Fig. 8). The intermingling of dwarf palms
and ferns, with the varied foliage of shrubs and herbaceous
plants, and the abundance of lianas hanging everywhere from
the trees overhead, give an impression of tropical luxuriance
beyond even that of the Malayan photographs pp. 48 and 49.
The system of small forest reserves in tropical or other im-
species of trees in IJ square mile, so that each species would be represented
on the average by 60 individuals. But, as some are comparatively common,
others rare, there would in some cases be only 3 or 4 specimens, while many,
having from 50 to 100, would be really abundant, but, if fairly scattered
over the whole area, even these might require searching for to find two or
three specimens; which accords with the facts as testified by all botanical
travellers.
!> *-'
z o
— o
I ^
^ u
W. *»
% ^
o >>
E=< ■=
<l
IS
GO ^
TEOPICAL FLORAS 81
perfectly known countries seems to ine to offer so many ad-
vantages that the adoption of it in Java by the Dutch botanists
must, I think, be looked upon as an important discovery. It
has the great advantage of being at once economical and ef-
fective; it brings about the maximum of scientific result with
the minimum of cost, of time and of labour. It has proved
that the careful and systematic study of very small areas is
calculated to extend our knowledge of the vast world of plant-
life more than any other that has hitherto been adopted. The
plan is to have, in any extensive country or island, a suit-
able number of what may be termed " botanical reserves "
(but which wdll also serve as zoological reserv^es, especially for
bird and insect life) ; these to be of small size, say one square
mile each, to be kept absolutely in a state of nature, except
the provision of numerous paths giving access to at least one
specimen of every species of tree the reserve contains. Ex-
perience in Java seems to show that one man, or two if
necessary, can keep the paths open, watch for the flowering
and fruiting of trees, gather and send specimens to the head
of the department, and also, I presume, serve as guide to any
botanical visitors to the reserve. But when the trees had been
all found, numbered, and named, the same superintendent
or keeper would have time and opportunity for the collec-
tion of specimens of all the shrubs, climbers, epiphytes, and
herbs that grew in the reserve, identifying the place of all
the rarer species by direction and distance from the nearest
named tree, the epiphytes, orchids, ferns, mosses, etc., being
identified by the tree they grew upon being numbered, and
made accessible by a path. Of course this area of 3 square
kilometres, or about a square mile, may not be in all
cases sufficient, but it seems likely to be the most suitable for
luxuriant tropical forests. In more open country, as at
Campo Santo, a space of from 10 to 50 square miles might
be advisable, because the trees on such an area might be as
easilv found as in a mile of unbroken forest, and w^ould not
be much more numerous. In any new tropical country of
82 THE WOKLD OF LIFE
Avhicli ^ve obtain possession, or where there are still large areas
of virgin forest, it would be advisable to reserve one square
mile in each square degree, say one in every 5000 square
miles.
There are many incidental advantages in this thorough de-
termination of the plants growing on a definite if small area
over that which has usually been adopted of, as it were, skim-
ming the cream of the flora of enormous areas, such as most
of our botanical collectors have been obliged to adopt. The
first advantage is that the census of species in each of the
reserved areas can be easily made exhaustive, and therefore
comparable with other similar reserves. Then, when a few
well-chosen " reserves " are similarly treated, the change of
species in each degree of latitude and longitude can also be
determined with considerable accuracv. In like manner the
change of species for each 1000 or 500 feet of elevation can
also be found. Again, the proportion of forest trees to the
whole of the flowering plants in each locality will enable the
whole flora of a large district to be determined as to numbers
by ascertaining the number of species of trees only in a few
small areas.
As an illustration of this mode of computation Dr. Koorders
has found that on the Pangerango mountain the trees form
one-fifth of the whole flora, while on Kambangan Island they
form one-fourth. If there are, as Dr. Koorders tells me,
about 1200 species of trees actually found in Java, and if,
on account of the eastern part of the island having much less
lowland forest, we take one-fifth as the more probable pro-
portion for the whole, then the flora of Java may be estimated
at a minimum of 6000 species; and if the number of the
trees is found to be greater, then at a proportionately higher
number. Hence it is very important that in each local flora
the number of its trees, shrubs, and herbs should be separately
given. It appears that a forest reserve of 17 square miles
has been established on the Bay of Manilla ; but, as it is as
yet very imperfectly explored, it would be more useful to
TROPICAL FLORAS 83
thoroughly explore two or three well-chosen areas of one square
luilo each.
It is really deplorable that in so many of our tropical de-
pendencies no attempt has been made to preserve for posterity
any adequate portions of the native vegetation, especially of
the virgin forests. As an example, the island of Singapore
was wholly covered with grand virgin forest at the begin-
ning of last century. When I was there in 1851 the greater
part of it was still forest, but timber-cutting and clearing
for gambir and other plantations has gone on without restric-
tion till there is now hardly any true virgin forest left ; and
quite recently the finest portion left has been allowed to be
destroyed by a contractor in order to get gi-anite for harbour
w^orks, which might almost as easily have been obtained else-
where. The grand forest trees were actually burnt to make
way for the granite diggers !
Surely, before it is too late, our Minister for the Colonies
should be urged without delay to give stringent orders that
in all the protected Malay States, in British Guiana, Trinidad,
Jamaica, Ceylon, Burma, etc., a suitable provision shall be
made of forest or mountain '' reserves," not for the purpose
of forestry and timber-cutting only, but in order to preserve
adequate and even abundant examples of those most glorious
and entrancing features of our earth, its native forests, woods,
mountain slopes, and alpine pastures in every country under
our control. It is not only our duty to posterity that such
reserves should be made for the purpose of enjoyment and
study by future generations, but it is absolutely necessary in
order to prevent further deterioration of the climate and de-
struction of the fertility of the soil, which has already taken
place in Ceylon and some parts of India to a most deplorable
extent. For this end not only must timber-producing forests
of an ample size be secured, but on all mountain slopes con-
tinuous belts of at least 400 or 500 yards wade should be
reserved wherever forests still exist, or where they have been
already lost be reproduced as soon as possible, so as to form
84 THE WOKLD OF LIFE
retainers of moisture by the surface vegetation, checks to
evaporation by the shade of the trees, guards against torrential
rains, mud slides, snow slides where such are prevalent, and
protection against winds. On level or nearly level ground,
where such varied uses would not be required, similar belts
at greater distances apart should be saved for local uses and
amelioration of climate, besides " botanical reserves " of ade-
quate extent to give a representation of each type of vege-
tation in the country.
I would also strongly urge that, in all countries where there
are still vast areas of tropical forests, as in British Guiana,
Burma, etc., all future sales or concessions of land for any
purpose should be limited to belts of moderate breadth, say
half a mile or less, to be followed by a belt of forest of the
same width; and further, that at every mile or half-mile,
and especially where streams cross the belts, transverse patches
of forest, from one to two furlongs wide, shall be reserved,
to remain public ]3roperty and to be utilised in the public
interest. Thus only can the salubrity and general amenity
of such countries be handed on to our successors. Of course
the general position of these belts and clearings should be
determined by local conditions; but there should be no ex-
ception to the rule that all rivers and streams except the very
smallest should be reserved as public property and absolutely
secured against pollution; while all natural features of es-
pecial interest or beauty should also be maintained for public
use and enjoyment.
The great Eoraima mountain in British Guiana, for ex-
ample, with at least half a mile of forest around its base,
should, so far as w^e are possessors of it, be absolutely se-
cured; and generally, every important mountain summit, with
ample means of access, should also be reserved, so that they
may not be monopolised or defaced by the greed of specula-
tive purchasers. It should always be kept in mind that the
reckless clearing of large forest-areas, especially in the tropics,
produces devastation which can never be repaired. It leads
TROPICAL FLORAS 85
to the denudation of the rich surface soil bj torrential rains ;
this soil has been produced by countless ages of forest growth,
and it will require an equal lapse of time to reproduce it.
Returning now to the more direct teachings of small areas
when methodically studied, I may add that Dr. Koorders has
informed me that some years since he made a visit to
Minahassa, in X. Celebes, and in four months, between the
sea-level and 6500 feet, he collected or observed about 2000
species of flowering plants, of wdiich about 700 were forest
trees. As these last are Dr. Koorders' special study it is
to be presumed he paid great attention to them, yet he could
hardly have obtained such a complete knowledge of them in
a few months as in the ^' reserves " of Java, where, in suc-
cessive years, not a single species could have escaped dis-
covery. This would imply that the forest flora of Xorth
Celebes is even richer than that of Java, and it is almost
certainly more peculiar. And if the larger islands of the
Moluccas — Gilolo, Batchian, and Ceram — are equally rich
(and they have all the appearance of being so), then every
estimate yet made of the species-population of the whole
Archipelago must be very far below the actual numbers.
There must be hundreds of young botanists in Europe and
America who w^ould be glad to go to collect, say for three
years, in any of these islands if their expenses were paid.
There would be work for fifty of them, and if they were prop-
erly distributed over the islands from Sumatra to Xew Guinea
in places decided upon by a committee of botanists who knew
the country, with instructions to limit their work to a small
area which they could examine thoroughly, to make forest
trees their main object, but obtain all other flowering plants
they met with, a more thorough and useful botanical explora-
tion Avould be the result than the labours of all other col-
lectors in the same area have accomplished, or are likely to
accomplish, during the next century. And if each of these
collectors had a moderate salary for another three years in
order to describe and publi^^h the results of their combined
8Q THE WORLD OF LIFE
work on a uniform plan, and in a cheap form, the total ex-
pense for all the nations of Europe combined would be a
mere trifle. Here is a great opportunity for some of our
millionaires to carry out this important scientific exploration
before these glorious forests are recklessly diminished or
destroyed — a work which would be sure to lead to the dis-
covery of great numbers of plants of utility or beauty, and
would besides form a basis of knowledge from which it woukl
be possible to approach the various great governments urging
the establishment, as a permanent possession for humanity, of
an adequate number of such botanical, or rather biological,
^' reserves '' as I have here suggested in every part of the
world.
Before leaving the very interesting problems suggested by
the floras of '' small areas," I will point out that in the tropics,
in warm temperate and in cool temperate zones alike, the evi-
dence goes to show that mountain floras are not so rich in
species as those of the plains. I have already shown that it
is the case in our own islands, in Switzerland and in South
Euroj^e. The table of extra-European small areas (p. 40)
shows that the gTeat Japanese mountain, Fujiyama, with a
larger area and an altitude of over 12,000 feet, has a smaller
number of species than Mt. Kikko, with a smaller area and
an altitude of only 8000 feet, both mountains being cultivated
to the same height (800 feet), and both being equally well
explored. And now, coming to the tropics, we find in Java
two areas of the same extent and fullv explored bv the same
botanist, one on a grand mountain slope from 4500 to 0500
feet, and celebrated for its rich flora, the other at the sea-
level, and the latter is decidedly the richest. Yet we find
Gardiner, in his Travels in Brazil, taking the very opposite
of this for granted. He says, at the end of his Avork : '' Xo
good reason has yet been suggested to account for the greater
number of species which exist on a given space on a mountain
than on a plain." The answer seems to be that there is no
TROPICAL FLORiVS 87
such general fact to be explained. There may often, no doubt,
be more plants on some mountains than on the adjacent plains,
especially on open plains where social plants abound. On
mountains the botanist can often collect more species in the
same time, because diversities of soil and station are more
crowded together, but the accurate determination of the species
on areas from one square mile up to some hundreds of miles
shows that the fact is almost uniformly the other way.
It is also of special interest to note that the well-known
fact in our own country, that a parish of 2 or 3 square miles
in area often contains more than half the flora of the whole
county many hundred times as great (as in the cases of Cad-
ney, Edmondsham, and Thames Ditton, given in the table),
appears to be even exaggerated in the more luxuriant tropical
forests, where a single square mile often contains as many
species as 100 miles in similar forests elsewhere.
It is, however, interesting to note that when we compare
very small areas, measured by feet or yards instead of by
square miles, it is the temperate floras which seem to have
a decided advantage. Darwin records that on a piece of turf
3 feet X 4 feet long exposed to uniform conditions, (prob-
ably on the chalk downs of Kent or the Isle of Wight) he
found twentj" species of plants belonging to eighteen genera
(Origin of Species, 6th ed. p. 88). Sir Joseph Hooker in
the Himalayas, 11,480 feet above the sea, in the upper Lachen
valley, found a much richer vegetation. He says : ^^ Herba-
ceous plants are much more numerous here than in any other
part of Sikhim; and sitting at my tent door I could, without
rising from the ground, gather forty-three plants, of which
all but two belonged to English genera." And in a note ho
adds : " In England thirty is on the average the equivalent
number of plants which in favourable localities I have
gathered in an equal area." ^
In my limited reading I have found no other reference to
this form of species-abundance, nor do any of my botanical
I Himalayan Journals (olieap ed.), p. 335,
88 THE WOELD OE LIFE
friends appear to have recorded such; hut it Avould be inter-
esting to know if any parts of Switzerland or the Pyrenees
were as rich as the Himalayas. I should expect not, as the
latter has a great advantage in area, and also I presume in
climate. The snow protection in winter would be similar,
but I presume the summer would be somewhat longer and the
temperature more equable, while the more nearly vertical sun
and much greater rainfall would probably lead to a more
luxuriant development of species than in higher latitudes, or
less elevated stations. Darwin points out that the produc-
tion of short velvety flower-decked turf depends entirely on
its being regularly cropped down by ruminants, preventing
the more delicate plants from being smothered by the coarser.
Now, this group of animals is one of the latest developments
of the world of life; and we thus learn that these delight-
ful expenses of flower-enamelled turf are actually produced by
the sheep or goats, the deer or antelopes whose presence gives
them a further charm, and which were themselves developed
just at the period when man appeared upon the earth, gifted
with faculties which enables him alone to fully appreciate
their beauty, and to utilise many of them as aids to his own
civilisation.
CHAP TEE y
THE DISTEIBUTIOiq^ OF ANIMALS
The sketch now given of the broader features of the distribu-
tion of plants over the various parts of the earth's surface
will apply, with little modification, to the various classes of ani-
mal life, which, although having the power of locomotion, are yet
by the necessity of acquiring food and preserving themselves
from enemies, almost as strictly limited to definite areas as
are plants themselves.
It will only be necessary to give a few facts to illustrate
this, for which purpose insects and birds afford the most in-
structive materials. We will begin with the Lepidoptera, or
Butterflies and Moths, in our own country and in a typical
county. The following data have been kindly furnished by
Mr. William Cole, F.L.S., Hon. Sec. of the Essex Eield
Club.
Distribution of Lepidoptera
Sq^Mfles. ^^''''''•
Great Britain 87,500 2070
Essex 1,530 1655
In order to compare the numbers in a smaller area, I have
only materials for the Macrolepidoptera or Butterflies and
larger Moths.
Sq^MHes. ^^'''''■
Great Britain 87,500 822
Essex 1,530 620
Epping Forest 10 428
It is interesting to note here the curious correspondence
with the number of the flowering plants, which in the mean
of twelve counties was almost tlio same as the area in miles;
89
90 THE WORLD OF LIFE
and here we find the total number of the Lepidoptera in
Essex, which is not far from an average county, very nearly
the same as its area. The number of species of these insects
is also suggestive, in being about one-half greater than the
number of flowering plants (1010) on which they almost all
feed in their larval state. We know that many different
species feed on some of our commonest plants — as the oak,
poplar, elm, nettle, etc. — while some larv^^e feed on several
distinct plants indiscr,iminately. But probably the larger
number feed on one species of plant only, and thus almost all
our plants, except the very rarest, afford food for at lea^t one
lepidopterous larva.
Again, just as we found that a selected area of 10 square
miles in Surrey had nearly two-thirds of the plants in the
whole county, so here we find that a selected area of 10 square
miles in Essex has nearly two-thirds of the Macrolepidoptera
found in the county. Here, too, we see the result of the de-
pendence of the insects on the plants, the great variety of
the latter in Epping Forest (150 species) rendering possible
a corresponding variety of the former.
Coleoptera (Beetles)
The enormous order of the beetles (Coleoptera) not being
exclusively feeders on living plants, but both in their larval
and perfect state often feeding on animal food or on vege-
table debris, are probably more uniform in their numbers in
different areas if not absolutely barren or very highly culti-
vated.
Area. Species.
Great Britain 87,500 3260
Essex 1,530 1655
As it requires perseverance in collecting for many years
in order to obtain all the beetles in even a very limited
district, I think it probable that the above figures do not so
closely represent the actual number of species inhabiting the
county as in those given for the plants, or even the moths.
THE DISTRIBUTION OF AOTMALS 91
To show the vast numbers and variety of the insect tribes,
I give here the approximate numbers of actually described
insects, kindly furnished me by Mr. C. O. Waterhouse of the
Entomological Department of the Natural History Museum.
Insects of the World. Number of Described
Species.
Coleoptera (Beetles) 120,000
Lepidoptera ( Moths and Butterflies ) 00,000
Hymenoptera (Bees, Wasps, Ants, etc.) 45,000
Diptera (Flies, Gnats, Midges, etc.) 28,000
Rhynchota (Bugs, Cicadas, etc.) 18,000
Orthoptera (Locusts, Crickets, etc.) 8,000
Neuroptera ( Dragon-flies, May-flies, etc. ) 5,000
Several smaller Orders 5,000
Land Area, 48,000,000 square miles 240,000
I
If we consider that large areas of the most productive
tropical regions are still almost unexplored by the ento-
mologist, and that even in the best-known parts the less
attractive groups are very little known, it is almost certain
that the actual number of species of insects now in existence
is double that above given, while it may be three or four
times as many.
To show how difficult it is to ascertain how many species
of insects are now known to exist, I give another recent esti-
mate by Mr. A. E. Shipley, F. R. S., in his Presidential
Address to the Zoological Section of the British Association
in 1909. This was based upon a careful estimate by Dr.
Giinther, in 1881, when Keeper of Zoology in the British
^luseum. His estimate then was 220,150 species of insects.
In the twenty-seven succeeding years, the 7.ooJogical Record
gives the number of new species described in all parts of the
world. During the whole of this time the numbers described
have increased vear bv vear, and Air. Shiplev has therefore
taken the number for the vear 1897 as an averaa'c of the
wliole (8364 n.s.), and multijdying this by 27 ('allowing the
odd 364 for synonyms) we have an addition of 216,000, which
92 THE WOKLD OF LIFE
added to 220,000 gives a total now known of JfS6,000, an
immense increase on the estimate of Mr. Waterhouse. Of
course a far more correct way would be to add the number
described as new, each year of the twenty-seven; but as this
would involve the counting of all the descriptions in thousands
of pages of close print, we cannot be surprised that such a
labour was not undertaken.
It is hardly possible for any one who has not collected
some special group of insects in countries where they abound,
to realise what the numbers given above really mean. In
the Malay Islands alone, I myself collected over a thousand
distinct species of one of the most beautiful families of beetles
— the Longicorns — of which about 900 were previously quite
unknown. Of another immense family — the Curculionidge,
or Weevils — I obtained also about 1000 species, of which the
same proportion were new. Wliile the former group are re-
markable for grace of form, variety of marking, and often for
exquisite colouration, the latter are equally interesting for
their endless modifications of shape, more sober but beauti-
fully marked bodies, strangely bossed surfaces, and, occa-
sionally, the most brilliant metallic colours.
The interest of making such collections, in which the variety
was so great as to seem absolutely endless, may be imagined
by any lover of nature. But the interest in their study has
been intensified by the firm conviction — the growth of half
a century of thought upon the subject — that every detail of
these wonderful modifications of structure, form, and coloura-
tion, have been due to general laws in operation for count-
less ages, and that every minutest character, as they occurred
through successive variations and became fixed in each species,
had a definite purpose; that is, were of use to the creatures
which exliibited them. This, however, will be shown later
on, when we have to deal with the more important factors
of evolution — variation and heredity.
THE DISTRIBUTION OF ANIMALS 93
The Species of Birds
We will now pass on to the most familiar, the most beauti-
ful, and the most wonderful of all living things — the birds.
These form one of the culminating lines of development of
the great world of life ; they are the most specialised of all
the higher animals ; and so far as perfection of organised
structure is concerned may be considered to hold a higher
place than the mammals themselves. Were they not so familiar
to us, we should consider it to be impossible that warm-blooded,
active creatures, with a bony skeleton, could have their fore-
limbs (or arms) so modified as to be used exclusively for
flight, and yet, with no organ of prehension but the mouth
prolonged into a beak, sometimes aided by a foot, be completely
adapted to obtain every kind of vegetable or animal food, to
protect themselves from enemies, and to construct the most
perfect abodes for their helpless young to be found among the
higher animals.
Some zoologists consider that in the power of flight birds
are surpassed by insects, but I cannot think this to be the
case. If we take into consideration the weight they have to
carry, the height they often attain above the earth, their per-
fect command over the direction and speed of their motion,
and the exquisite and highly complex organ by which flight
is effected, birds must take the higher place. The insect's
flight is simpler and more automatic; that of the bird more
elaborate in every part, more completely under the control
of the creature's will. It is also, I believe, more varied in
exact adaptation to the mode of life of each of the species.
As regards their variety of structure, the numbers of the
species, and their mode of distribution over the earth's sur-
face as compared with the other forms of life already con-
sidered, a few examples will be sufficient to prove their general
correspondence with other animals. It must be remembered,
however, that in birds the numbers inhabiting the several
countries are less precise and less comparable than in any other
94 THE WORLD OF LIFE
group. This is due to several causes. In all extra-tropical
lands a large proportion of the species are migratory, and the
facts observed are very similar over the whole of the north
temperate zone. Some go to more northern lands in summer
to breed, returning south in autumn ; others leave us in autumn
to winter in the south, returning to lis in the spring; others,
again, are birds of passage only, staying with us a few days
or weeks on their way north or south. All these are con-
sidered to be truly natives, in our case to be ^' British birds."
But others only visit ns occasionally, some at very long inter-
vals, while others, again, are mere " stragglers," who have
lost their way or been driven to us by storms, and have only
perhaps been recorded (seen or killed) once or twice. There
is therefore a vast range for personal opinion as to what species
should or should not be included as " British " or " European "
or '^ Canadian " birds. If we add to this uncertainty the
extreme variety of opinion as to the limits of ^' species," " sub-
species," and " varieties," or ^' local races " of birds which
now exist, we see how hopeless it is to expect uniformity in
numerical estimates of the birds of different countries or re-
gions. As an example of this difference of treatment, we may
take two of the most recent estimates of the bird-population
of the world. Dr. Glinther, in 1881, estimated the species
of birds then known at 11,000, and Mr. Shipley added to this
an average of 105 new species per annum — estimated from
the y.oological Record — for the twenty-seven years elapsed
since that date, bringing the total up to 13,835. But in the
late Dr. Bowdler Sharpens Hand List of the Genera and
Species of Birds, just completed, the number is stated as being
18,937. This enormous divergence, as I am informed by an-
other great authority on Ornithology, Dr. P. L. Sclater, is
mainly, if not wholly, due to the fact, that Dr. Sharpe '^ in-
cludes as species all the numerous slight local forms which
are called ' sub-species ' by the new school of Ornithologists,
many of which, in my opinion, do not present sufficient dif-
ferences to require separation at all."
THE DISTRTBUTIOIsr OF AXIMALS
95
Keeping tlicse difficulties iu mind, the following estimates,
for which I am largely indebted to my friend, Mr. Henry
Dresser (author of a great work on the Birds of Europe), will
be found interesting.
Species of Birds
Square Miles.
Europe
Great Britain
Dorset
3,850,000
87,000
988
Number of Species.
770
410
2101
Mansel-Pleydell's Birds of Dorset.
The numbers for Dorset are obtained by omitting all the
" stragglers " and very rare visitors, including all that are
regular immigrants or birds of passage, as well as those which,
though irregular, are tolerably frequent visitors. Here, again,
we see that a county area has rather more than half the
British species, as was the case wdth flowering plants and
some of the most extensive orders of insects.
The difficulty of obtaining really comparable figures for the
countries and regions shown on page 96 is at present insuper-
able, but the approximations given are of considerable interest.
The same table exhibits several points of interest, espe-
cially as regards the correspondence of the proportionate
numbers of such different organisms as birds and plants. As
regards the Palsearctic and N^earctic regions (temperate
Europe and Asia on the one hand, temperate North Am.erica
on the other), we see that the birds of the former are about
one and a half times those of the latter, the areas being nearly
as two to one. The plants are probably not far from the
same proportion; for if we take those of Europe with North
Africa at 10,000, and add thereto those of the Flora Orientalis
of Boissier (12,000), and the China flora of Hemsley (9000),
and allowing that the species common to any two of these may
96
THE WOELD OF LIFE
Table of the Species of Birds
Region or Country.
Palaearctic Region
Nearctic Region
Ethiopian Region
Oriental Region
British India
Borneo
Philippines
Neotropical Region
Central America and
South Mexico
Brazil
Australian Region
Australia
New Guinea
Area,
Sq. Miles.
17,000,000
8,000,000
7,555,000
3,350,000
1,560,000
297,000
115,500
7,590,000
940,000
3,288,000
3,500,000
3,009,000
310,000
Number
of
Species.
1250
760
2490
2300
1617
500
700
4100
1300
1568
883
950
Dresser.
Ridgway.
Reichenow,
Estimate.
Dresser
Ernst Hartert (1910)
Biol. Am. Cent. (1905),
Von Thering (1907).
E. Hartert (1908).
Ernst Hartert.
The numbers for the Oriental Region have been estimated on the method of Mr.
Shipley above referred to; and the same has been done for the Neotropical and
Australian Regions.
The numbers for Central America and Mexico have been reduced from those of
the Biologia Am. Cent., because that work includes all temperate Mexico with a
large number of Nearctic species.
be about equal to additional species of the whole of N'orth
Asia and Japan, we get a total of 31,000 species, which is
far beyond the highest estimate of the Xearctic flora with all
the sub-species included.
The birds of the Ethiopian and Oriental Regions appear
to be approximately equal in numbers. The flowering plants
are even less known. Those of tropical Africa with Madagas-
car, Mauritius, etc., must reach about 22,000 species; while
temperate South Africa has 13,000. Allowing the species
common to both to equal those yet undescribed from tropical
Africa, we get a total of 35,000 species for the Ethiopian
flora.
That of the Oriental Rei^ion is much more difficult to ar-
rive at. Taking 15,000 species for the tropical portion of
the flora of British India, and addins: 7000 for Indo-China,
THE DISTEIBUTIOX OF AXIMALS 97
5000 for the Pliilippincs, 4000 fur Java, and the same for
additional species of Makiysia proper (Malay Peninsula,
Borneo, and Sumatra), and 2000 for Celebes, Ave have a total
of 30,000, Avhich, considering that the land area of this region
is less than half that of the Ethiopian, shows Avhat is prob-
ably a fair approximation to the number of its flowering
plants; though I believe it will be below rather than above
the actual amount.
Coming now to the [N'eotropical Region (including all South
America and tropical Xorth America), we find our estimate of
the birds to be almost double that of either of the other tropical
regions. By means of a rough estimate (p. 64) I have arrived
at 80,000 species as a not improbable number of the flower-
ing plants for the [N^eotropical Region ; and allowing fully for
future discoveries in the Malayan Islands and Indo-China, the
numbers in the Oriental Region are not likely to much exceed
half this number, thus agreeing very well with the proportion-
ate numbers of birds in the same regions.
The Australian Region is of less importance from the
point of view we are now considering, because it is not ex-
clusively temperate or tropical, but nearly equally divided be-
tween the two. It also differs from the Oriental inasmuch
as botanists usually claim the flora of the Moluccas and Xew
Guinea as being essentially Malayan, and therefore belonging
to the Oriental Region. But the flora of Xew Guinea has
been stated by Sir Joseph Hooker to be so peculiar as al-
most to deserve to form a Sub-region of its own ; and, till
recently, the natural order Dipteracese, consisting of lofty
forest-trees with very distinctive botanical characters, was
supposed to be limited to the Oriental Region, from the
Himalayas to Java, Celebes, and the Philippines. They have,
however, now been found both in the ^Moluccas and Xew
Guinea ; but as westerly winds blow^ for half the year with
great steadiness between Celebes and Xew Guinea, it is not
difficult to explain their presence in the latter country, as their
solid but larire-winc-ed fruits would be easilv drifted for lonff
98 THE WORLD OF LIFE
distances. At all events the extreme richness of Xew Guinea
in both birds and plants, and not improbably in insects also,
is a matter of very great interest.^
Having shown by the best statistics available that the general
phenomena of the numerical distribution of species over small
or large areas correspond in their main features for such
diverse groups of organisms as plants, insects, and birds, it
is quite needless — even if it were possible — to attempt a
similar enumeration for other groups. In reality, with the
one exception of land-shells, the materials do not exist for
any other organisms. Even the mammalia and reptiles have
never been systematically collected in tropical countries, as
hirds and insects have been collected, and what materials do
exist are more difficult to obtain. But to give the general
reader some notion of the extent of the whole world of life
as now studied by biologists, I will give a tabular statement
of the numbers supposed to be actually described, from the
estimate made by Mr. Shipley above referred to in the case
of insects.
As regards these figures, I am informed by Mr. R.
Lydekker that he considers the Mammalia to be much exag-
gerated by writers who reckon slight local forms or varieties
as distinct species. Thus 8 species have been made of the
common brown bear, and 16 species of various local forms
of mouse-deer (Tragulus). On the other hand, although the
number of insects here given seems enonnous, Mr. D. Sharp,
a very experienced entomologist, thinks that the number ac-
tually existing is five times as great — that is, more than two
million distinct species !
1 Eor a full explanation of the six great Zoological Regions, here enu-
merated, the reader is referred to my Geographical Distribution of Animals,
vol. i. chap. iv. ; or for a more popular account of them to my Island Life,
chap. ill.
THE DISTRIBUTION OF ANIMALS
99
An Estimate of the Described Species of Living Animals.
By A. E. Shipley, F.R.S. (B. Essii. Address, 1909).
Class.
Estimated by
Giinther, 18«1.
A. E. Shiplev,
1909.
Remarks.
Mammalia
2,300
11,000
3,400
11,000
33,000
120
7,500
8,070
1,300
220,150
1,840
6,070
2,200
400
3,300
9,955
13,835
7,180
14,996
62,000
222
13,953
25,870
8,725
445,978
15,097
8,716
5,008
2,965
6,000
Too hi»li !
Birds
(R. Lydekker).
18,939
(R. B. Sharpe).
Reptiles, Batrachia
Fishes
MoUusca
Brvozoa,
Crustacea
Soiders. etc
MvriaDods
Insects
Too low!
Echinoderms
(D.Sharp).
Coelenterata
.
Snono-es
Protozoa
790,533
CHAPTER VI
THE I^UMEEICAL DISTEIBUTION OF SPECIES IN RELATION" »
TO EVOLUTION
The rather lengthy account I have given of the numerical
distribution of species over both small and large areas, and
in special relation to latitude and to climate, has a very def-
inite object. In the first place, this distribution constitutes
the primary and fundamental fact in the relation of species
to the whole environment — it is, in fact, the broadest and
most simple expression of that relation, and is thus a proper
subject of inquiry in any general view of the world of life.
Yet it has been strangely neglected both by botanical and
zoological writers; and the largest and oldest collections of
plants and animals in all countries have been so dealt with as
to afford material for almost every form of biological research
except this one.
The mere enumeration of the numbers of species^ named or
unnamed, with the localities of each specimen, in the great
national collections of the world, would have afforded all the
materials for such comparisons as I have here endeavoured to
make. And if the facts were recorded in card-catalogues,
instead of in the usual forms, there would be such a demand
for sets of these cards applying to special groups and definite
geographical areas, by most students or collectors, that the cost
of such catalogues would be more than repaid.
This numerical relation of the various groups of organisms
in different areas or geographical divisions of the earth has
the further advantage of being interesting and intelligible to
the general reader, as it involves the use of hardly any tech-
nical terms, and is therefore especially suitable for a work
100
DISTKIBUTION AND EVOLUTION 101
such as the present. We will now proceed to a brief considera-
tion of the nature and meaning of the facts set forth in the
preceding chapters.
The evidence, collected with extreme care for many years
by Mr. Woodruffe-Peacock (as explained in Chapter 11.)? has
shown us how curiously the number of species differs even
on the smallest adjacent areas. In the same field, even when
apparently alike everywhere in soil, in aspect, and in contour
of surface, every plot of 16 feet square has its individuality.
It will differ from each of the eight adjacent plots either in
tlie number of the species it contains, or in the species them-
selves, or in the proportions of the individuals of the various
species. They are thus seen to be affected by very small
differences, such as moisture, or aridity; more or less
shade from hedges, trees, or woods; shelter from or ex^^osure
to winds; by the vicinity of pits or quarries, woods, ponds,
or streams.
Now this one fact of response to the minutest change of
conditions in the arrangement of a few^ species over almost
identical adjacent areas is as much a case of adaptation to
the environment through the mutual interaction of the various
species — a struggle for existence on the very smallest scale
' — as any of those larger and more complex cases which Dar-
win first made known to us.
Coming now to the fields themselves of various shapes and
dimensions, and each limited by definite boundaries of hedge
and ditch, bank or wall, spinneys, plantation or woods, we
have, in our country especially, a series of unit-areas which
may be said to form the first step in the study of botanical
geography, and which leads us on through successively larger
areas to regions and continents.
In regard to these fields, the writer above quoted not only
states their precise differences in the numbers of their species
and the presence of certain species and absence of others which
give to each its individuality, but lie is able in many cases
to define the causes of that individiialitv. Besides the or-
102 THE WORLD OF LIFE
dinarj variations of soil, we have to take account of the effects
of diversity of treatment as meadows, pasture, or fallow land,
each resulting in a characteristic grouping of species easily
recognisable over wide areas. In pasture land each kind
of domestic animal leads to the presence or absence of certain
species, while in the vicinity of farms or villages, the presence
of geese, pigs, or poultry has a distinctive influence.
What a new light these researches throw upon the develop-
ment of the vegetation of each country during past ages ! We
see how the indigenous vegetation of oceanic islands, in the
total absence of mammalia, must have gradually eliminated
some of the chance immigrants by which they were first
stocked, and favoured others often of later date, and how, in
the com^^etition with each other, those species which were most
easily modified into a shrubby or arboreal type would have the
advantage. Thus may we explain the composites, lobelias,
violets, and plantains of the Sandwich Islands being mostly
shrubs or even trees of considerable size, and so abundant in
species as to form a characteristic feature of the vegetation.
Numerous Caryophyllacese, Primulacese, and a Geranium are
also shrubs or small trees. In the Azores a Campanula and
a Sempervivum are shrubs.
Again, the knowledge we have recently gained of the won-
derfully rich mammalian fauna of temperate Xorth America
in middle and late Tertiarv times — camels, ancestral horses
and cattle, mastodons, and many others, which disappeared
at the on-coming of the glacial epoch — affords us a very im-
portant clue to the development of its special vegetation.
Every change of animal life that so often occurred in all the
continents — the union and separation of the sub-arctic lands
at various epochs, the temporary separation of Xorth and South
America in late Tertiarv times, and that of Africa from
Europe and Asia during the Early and Middle Tertiary —
must all have profoundly affected the special developments
of the vegetation, as well as of the animal life, in the respec-
tive areas.
DISTKIEUTION AND EVOLUTION 103
No less indicative of delicate response to variation of tem-
perature, and therefore of close adaptation to the whole modi-
fied environment, is the continuous increase in the number
of species with every important change of latitude. Although
this increase is but slight for moderate changes, and is there-
fore liable to be masked by other favourable or adverse con-
ditions of the environment, it yet makes itself visible in every
continent ; and in the comparison between the north or mid-
temperate and the tropical zones is so pronounced that in fairly
comparable areas the tropical species are often (and probably
on the average) double those of the temperate zones. This
seems to be the case among the higher animals, as well as
among all the vascular plants.
Now all this is indicative of long and minute adjustment
to the special inorganic as well as the organic conditions ; and
the reason why the tropics as a whole far surpass the temper-
ate zones in the number of their specific forms, is, not the
greater amount of heat alone, but rather the much greater
uniformity of climatical conditions generally, during long
periods — perhaps during the whole range of geological time.
Whatever changes have occurred through astronomical causes,
such as greater excentricity of the earth's orbit, must neces-
sarily have produced extremes of climate towards the poles,
while the equatorial regions would remain almost unaffected,
except by a slight and very slow rise or fall of the average
temperature, which we know to be of little importance to vege-
tation so long as other conditions remain tolerably uniform
and favourable.
It is this long-continued uniformity of favourable condi-
tions within the tropics, or more properly within the gi'eat
equatorial belt about 2000 miles in width, that has permitted
and greatly favoured ever-increasing delicacy of adjustments
of the various species to their whole environment. Thus has
arisen that multiplicity of species intermingled in the same
areas, none being able, as in the temperate zone, to secure such
.a superior position as to monoj)olise large areas to the exclu-
104 THE WOELD OF LIFE
sion of others. Hence also it has come about that the equa-
torial species seem to be better defined — more sharj^ly dis-
tin2;nished from each other — than manv of those of the tem-
perate and northern zones. They are what Dr. Beccari terms
first-grade species, as in the case of Borneo, an island which
forms part of what has quite recently been an equatorial con-
tinental mass. It is interesting to note that Mr. Th. D. A.
Cockerell has arrived at a similar conclusion from his study
of the rich fossil flora of Florissant, Colorado, of middle or
late Tertiary age, which shows signs of a much milder climate
than now prevails there. Many of these plants are of genera
now extinct or only found in more southern lands, and this ex-
tinction is traceable to the great changes, inorganic and or-
ganic, that have since occurred in Xorth America. He says
(in a private letter) :
" There was first the invasion of Old World species via Behring's
Straits; then an incursion of S. American forms via Panama; and
then the glacial period at the end, crowding and destroying much
of the flora and fauna. Since the glacial period in X. America,
there has been room for expansion, and hence the very numerous
and closely allied species of Aster, Solidago, Senecio, and other
jolants, as well as allied species of butterflies of the genera Arg}^nnis,
Colias, etc. These are, most of them, not at all on the same footing
as the tropical species. ... I think tropical species are better
defined than those of the temperate region.''
It is a rather curious coincidence that if we take the mean
area of the twelve English counties for which I have been
able to give the figures, in geographical instead of English
miles, the number of square miles will almost exactly equal
the average number of their species of flowering plants. Be-
low this area, in the mid-temperate zone, the proportion of
species decreases, and above it increases, in both slowly at
first and with many fluctuations, but afterAvards very rapidly,
more especially for the larger areas, so that it requires on a
rough average about a two hundred-fold increase of area to
double the number of species, and about a thousand-fold to
DISTRIBUTION A^B EVOLUTION 105
qiuntuple it. But in all such comparisons we require a large
number of fairly comparable cases to give a trustworthy
average, and the materials for this do not seem to exist. Yet
there is a striking general agreement between the numbers
of the species in the various kingdoms, states, or colonies of
Europe, North America, and Australia, requiring only slight
allowances for greater area, better climate, or geological history
to bring them into line with one another to a really remarkable
degree.
It appears, then, that, whether we take small areas roughly
approximating 100 square miles, or much larger areas of from
100,000 to 200,000 square miles, there is, over the whole world,
an unexpected amount of agreement in the numbers of the
flowering plants, but always showing a moderate increase from
the colder to the w^armer parts of the earth.
Differences of Temperate and Tropical Vegetation
One of the chief differences between the floras of the colder
and of the warmer parts of the earth (already referred to) is
the greater prevalence in the former of gregarious plants. To-
wards the northern limit of vegetation we find continuous
forests of pines or firs, the same species often extending for
hundreds or even thousands of miles ; while woods of birches
extend even farther north almost up to the limits of perpetual
snow, and in this case a single species — our common birch — •
extends entirely across northern Europe and Asia, with allied
species in North America. Earther south, forests of beeches,
oaks, chestnuts, etc., are common, but seldom covering such
large areas, being dependent on conditions of soil as well as
of climate; while in the warmer parts of the temperate zone
the forests are often made up of a gTeat variety of trees,
though never so completely intermingled as in the typical areas
of the tropics.
Another, and perhaps more important character of the
tropical flora, is the large number of distinct types of vegeta-
tion which are almost or quite peculiar to ihe warmest and
lOG THE WORLD OF LIFE
most equable regions of the earth. This is indicated by the
fact that about one-fourth of the natural orders of plants are
either exclusively tropical or very nearly so, and that they
comprise such remarkable forms as the epiphytic Orchids, the
Bromelias, the Palms, the Pitcher-plants, Bananas, Bread-
fruits, the Coffea and Cinchona trees, and hundreds of others
almost unknown except to botanists.
But the most striking feature of all is the wonderful adapta-
tions by which every w^ell-marked place or station is occupied
by peculiar groups of plants. The epiphytes above referred to
• — plants which live upon trees, upon the trunks or branches,
and especially in the forks, where they can root and establish
themselves, not as parasites by sending their roots into the
living tissues of the tree, but solely getting nourishment from
the rain-water that trickles down the bark or the small quan-
tity of decaying leaves or moss that collects there — such
plants belong to many natural orders and are very numerous.
Then there are the climbers, far more abundant than in any
temperate forests, which either root in the ground and then,
by various means, climb up to the summits of the loftiest
trees, or which begin life by rooting in a lofty fork of a gi-eat
tree, and then send down roots to the ground and branches
into the air, sometimes remaining as a small bush or tree, at
others growing so rapidly above, and clinging around the sup-
porting tree so closely with its roots, as finally to kill its foster-
parent, when its clinging roots unite and grow into a trunk,
with hardly anything to show that one tree has replaced an-
other. Then again there are numerous small trees of from 20
to 30 feet high, which live entirely in the shade beneath the
great forest trees. Many of these have bright-coloured or con-
spicuous flowers growing directly out of the trunk, while there
are none at all among the crown of leaves at the top. This ap-
pears to be an adaptation to bring the flowers within sight of
the butterflies, bees, and other insects which fly near the
ground, and thus secure for them the advantages of being
cross-fertilised. Then again there are many delicate creeping
DISTRIBUTION AND EVOLUTION 107
plants, especially mosses and hepaticse, that cover the whole
surfaces of the leaves of forest trees with an exquisite tracery,
thus obtaining the perpetual moisture they require from con-
densation on the cool surfaces of the leaves.
in great river valleys, where by the annual rising of the
stream miles of alluvial plains are regularly under water for
several months, both trees and shrubs have become adapted to
these strange conditions, and the greater part, if not all, the
species are quite distinct from those which grow on the un-
flooded land.
All these, and many other characteristic features of tropical
vegetation, can be explained by the general constancy of the
inorganic conditions, especially the climatic ones, which have
undoubtedly prevailed there during whole geological periods,
subject only to those very slow changes due to elevation, de-
pression, and denudation of the land itself. These latter have
been so extremely gradual as to act as a gentle stimulus to the
various agencies continually bringing about modification of
specific form? ; and as the climatal conditions throughout all
these changes have continued to be highly favourable to the
support of vegetation and of animal life, there has been a con-
stant tendency to produce and maintain an almost exact
equilibrium between the various species in the same area.
None being better adapted to the environment than a great
many others, none are able to monopolise large areas to the
exclusion of others, as is the case in the more changeable tem-
perate or cold regions. Whether we consider the differences
between day and night temperatures, the variations of tem-
perature from month to month or from year to year, or those
extreme variations which we experience once perhaps in a gen-
eration or in a century, such as excessively cold winters, ex-
cessive droughts or excessive rains in summer, or long periods
of dry and cold winds — all alike are unkno\\Ti in the equa-
torial regions, save in a few^ limited and quite exceptional areas.
In these more favoured portions of our earth there prevails
such a general approach to uniformity of conditions (without
108 THE WOELD OF LIFE
ever reaching absolute uniformity) as seems best adapted to
bring about the greatest productivity, together with extreme
diversity in every department of the great world of life.
The large amount of diversity of species we have seen to oc-
cur in single fields long subject to almost identical conditions
in our own country, wdth the additional fact that no plot of a
fev7 square yards has exactly the same grouping of species and
individuals as any of the other plots, yet each plot produces
very nearly the same number of species, will enable us in some
degree to appreciate the conditions of the tropics. There we
see enormous areas subject to almost identical conditions of
soil, climate, and rainfall, yet in every part of it exhibiting,
amid a general -uniformity of type, a wonderful diversity in
the shapes and structures of the forms of life, and a no less
w^onderful balance and adaptation of each to all. How this
result has been actually brought about in the course of evolu-
tion through the ages we shall better understand after a brief
exposition of the factors wdiich have been the immediate causes
of the two great phenomena, continuous evolution, with con-
tinuous adaptation.
CHAPTEE VII
HEREDITY, VARIATION, INCREASE
In the preceding chapters I have shown how, from a con-
sideration of the simple facts of the numerical distribution of
species over the earth, together with the varying numbers of
the individuals in each species and the area occupied by them,
we are led to the conclusion that there is an ever-present strug-
gle for existence between species and species, resulting in a
continual readjustment to the environment. In this view
there is no question of any change of species, but merely of
their redistribution; we perceive that during the process very
rare or local species may, and certainly do, die out, but we
have obtained no clue to the method by which new species arise
to replace them.
This was the state of opinion among the most advanced
writers before Darwin, and it is very clearly expressed in the
admirable 42nd chapter of Sir Charles Lyell's Principles of
Geology (11th edition, 18 68, but w^hich first appeared in the
9th edition, 1853, pp. 689-701) many years before the idea
of the transmutation of species had been seriously entertained
by men of science. This chapter may still be read with in-
terest even by the evolutionist of to-daj^ The reader will then
be better able to appreciate the enormous advance made by
Darwin by his conception of " natural selection," dependent
on the three fundamental factors — heredity, variation, and
enormous powers of increase — all well known to naturalists,
but whose combined eifect had been hitherto unperceived and
neglected. The two first of these factors we will now pro-
ceed to discuss and elucidate.
Perhaps the most universal fact — sometimes termed ^' law "
— of the organic world is, that like produces like — that off-
109
110 THE WORLD OF LIFE
spring are like their parents. This is so common, so well
known to everybody, so absolutely universal in ordinary ex-
perience, that we are only surprised when there seems to be
any exception to it. In its widest sense as applied to species
there are no exceptions. Not only does the acorn always pro-
duce an oak, the cat a kitten, which grows into a cat, the sheep
a lamb, and so throughout all nature, but each different well-
marked race also produces its like. We recognise Chinese and
Negroes as being men of the same species as ourselves but of
different varieties or races, yet these varieties always produce
their like, and no case has ever occurred of either race pro-
ducing offspring in every respect like one of the other races,
any more than there are cases of cart horses producing racers
or spaniels producing greyhounds.
Some people still think that mental qualities are not in-
herited, because it so often happens that men of genius have
quite undistingaiished parents, and that the children of men
of great ability do not as a rule equal their fathers. But al-
though such cases are frequent and attract attention because
such apparent non-inheritance is unexpected and seems un-
reasonable, yet when large numbers of families are carefully
examined there is found to be the same amount of mental as
of physical inheritance. This was proved by Sir Francis
Galton in his work on Hereditary Genius, in which, by tracing
the families of large numbers of public men of high position
and some kind of exceptional talent or genius which was gen-
erally recognised, it was found that in their ancestral line
there was always found some amount of distinction, though
not always of the same kind or degree; and that if they left
descendants for two or three generations, they, too, usually
comprised some individuals of more than average ability.
To avoid any misconception on this point, it may be as well
here to state brieflv the numerical law of inheritance, which
Galton arrived at by careful experiments in the breeding of
plants and animals, and which is now generally accepted as
affording a very close representation of the facts of inherit-
HEREDITY, VARIATION 111
V
ance under normal conditions. It is that the offspring of any
two parents derive, on the average, one-half of their character-
istics from tliose parents, one-fourth from their four grand-
parents, one-eighth from their eight great-grandparents, and
so on to remote ancestry, the total result being that one-half
of each individual's peculiarities is derived from its parents,
while the other half comes from its whole previous ancestry.
Hence arises the Avell-known fact that certain peculiarities of
body or of character are apt to reappear in families during
several centuries.
Xow this simple law explains almost all the facts including
the apparent failures of inheritance — all its irregularities in in-
dividual cases, together with its constancy and regularity when
larse numbers are examined. It shows us whv, when families
for several generations have been noted for beauty, for stature,
for strength, or for talent, these characters will almost cer-
tainly be found developed in most of their children, who from
three or four generations of ancestors have a good chance of de-
riving seven-eighths or fifteen-sixteenths of their entire or-
ganisations. If, on the other hand, the beauty or talent of
jjarents were exceptional in their respective families, then
iheir children, having a number of commonplace or inferior
ancestors, w^ould often be far inferior to their parents in the
particulars in which the parents excelled, and in their case
heredity would seem to have failed.
Erom this consideration there is deduced another general
law, very easy to remember and of great use in explaining ap-
parent deviations or incongruities. This is called the '^ law" of
recession towards mediocrity." It means that, whenever par-
ents deviate considerably from the average of the population
of which they form a part, their offspring will tend to return
towards the average. Eor example, if both parents are de-
cidedly below or above the average in height, in beauty of
form, in any special faculty, as music, drawing, etc., their chil-
dren will usuallv ffo back towards the averaii'e, thou2:li still re-
taining some of the parental excess or defect. It is owing to
112 THE WORLD OF LIFE
tliis law that very extreme developments, whether of body or
of mind — gigantic stature or supreme genius — are rarely
transmitted to the next generation. But if this special su-
periority has already persisted in the family for several gen-
erations, and both parents belong to this same superior stock,
then the reversion towards mediocrity is less marked, and the
special quality will almost certainly be transmitted, sometimes
even in still larger degree, to some members of the family.
It is by acting on this principle that breeders of animals or
j^lants for special purposes are able to improve the race. In
each generation they choose the most perfect individuals, from
their point of view^, to be the parents of the next generation, re-
jecting or destroying all the inferior ones. It is in this way
that our race-horses, our best milking cows, our heavy-woolled
sheep, our quickly fattening pigs, our luscious pears and
peaches, and hundreds of others, have been produced. Just
in proportion as we have bred only from the best for a long
series of generations does the transmission of these qualities
become more certain and the '' recession tow^ards mediocrity "
appear to be abolished. But it is not really abolished. The
average to w^hich there is a tendency to return has itself been
raised by careful selection of the best for many generations,
and the inferior individuals which were once the average of
the race are now so far removed that they can exert only a
very slight influence on each successive generation. Owing to
the numerical law above referred to, after five generations of
such selective breeding it is about 100 to 1 against the inferior
characters of the original average stock reappearing in the
offspring, while if the operation has been carried on for ten
generations it is about 2000 to 1 against such inferior types
presenting themselves. It is for this reason that our great
Colonial sheep and cattle breeders find it to their advantage
to give even thousands of pounds for pedigree bulls or rams
in order to improve their stocks.
It is by what is substantially the same process, as wt shall
see farther on, that nature works to improve her stocks in the
HEEEDITY, VAEIATION 113
great world of life ; and has been thus enabled nut only to keep
all in complete adaptation to an ever-varying environment, but
to fill up, as it were, every element, every different station,
every crack and crevice in the earth's surface with wonderful
and beautiful creatures which it is the privilege and delight
of the naturalist to seek out, to study, and to mar\^el at.
The Variation of Species, its Frequency and its Amount
Having now shown something of the nature of heredity, its
universality and its limitations, we pass on to a rather fuller
discussion of the nature and amount of those limitations, com-
monly known as the variability of species. It is this variability
that constitutes the most important of the factors which bring
about adaptation, and that peculiar change or modification of
living things which we term distinct species. This change is
often very small in amount, but it always extends to various
parts or organs, and so pervades the whole structure as to
modify to a perceptible extent the habits and mode of life, the
actions and motions, so that we come to recognise each species
as a complete entity distinct from all others.
There is no subject of such vital importance to an adequate
conception of evolution, w^hich is yet so frequently misappre-
hended, as variability. Perhaps owing to the long-continued
and inveterate belief in the immutability of species, the earlier
naturalists came to look upon those conspicuous cases of varia-
tion which forced themselves upon their attention as something
altogether abnormal and of no importance in the scheme of
nature. Some of them went so far as to reject them altogether
from their collections as interfering with the well-marked dis-
tinctness of species, which they considered to be a fundamental
and certain fact of nature. Hence, perhaps, it was that Dar-
win himself, finding so little reference to variation among wild
animals or plants in the works of the writers of his time, had
no adequate conception of its universality or of its large general
amount whenever extensive series of individuals were com-
pared. He therefore always guarded himself against assuming
114 THE WORLD OF LIFE
its presence whenever required bj using such exj^ressions in
regard to the power of natural selection as, '' If thej vary, for
unless thej do so, natural selection can effect nothing."
This was the more strange because wherever we look around
us we find, in our own species, in our own race, in our own
special section of that race, an amount of variation so large
and so universal as to fully satisfy all the needs of the evolu-
tionist for bringing about w^hatever changes in form, structure,
habits or faculties that may be desired. By simply observing
the people we daily meet in the street, in the railway carriage,
at all public assemblages, among rich and poor, among lowly-
born or high-born alike, variability stares us in the face. We
see, for instance, not rarely, but almost daily and everywhere,
short and tall men and w^omen. We do not require to measure
them or to be specially good judges of height to be able to
observe this — the difference is not one of fractions of an
inch only, but of wdiole inches, and even of several inches.
We cannot go about much without constantly seeing short
men who are about 5 feet 2 inches high, and tall men who are
6 feet 2 inches — a difference of a w^hole foot, while in almost
every town of say 10,000 inhabitants, still greater differences
are to be found.
But this special variation, so large and so frequent that it
cannot be overlooked, is only one out of many which we may
observe daily if we look for them. Some men have long legs
and short bodies, others the reverse ; some are long-armed, some
are big-handed, some big-footed, and these differences are found
in men differing little or nothing in height. Again we have
big-headed and small-headed men, long-headed and round-
headed, big-jawed, big-eared, big-eyed men, and the reverse;
we see dark and light complexions, smooth or hairy faces ;
black, or brown, or red, or flaxen-haired men; slender or stout
men, broad or narrow-chested, clumsy or graceful, energetic
and active, or lazy and slow. Characters, too, vary just as
much. Men are taciturn or talkative, cool or passionate, intel-
ligent or stupid, poetical or prosy, witty or obtuse. And all
HEREDITY, \^xUaAT10X 115
these characteristics, whether physical or mental, are combined
together iii an infinite variety of ways, as if each of them
varied independently with no constant or even usual associa-
tion with any of the others; whence arises that wonderful
diversity of appearance, attitudes, expression, ability, intellect,
emotion, and what we term as a wdiole character, which adds
so much to the possibilities and enjoyments of social life, and
gives us in their higher developments such mountain peaks of
human nature as were manifested in Socrates and Plato, Homer
and Virgil, Alexander and Phidias, Buddha and Confucius in
the older world ; in Shakespeare and ^N^ewton, Michael Angelo,
Faradav, and Darwin in more recent times.
And with all this endless variation wherever we look for it,
we are told again and again in frequent reiteration, that varia-
tion is minute, is even infinitesimal, and only occurs at long
intervals in single individuals, and that it is quite insufficient
for natural selection to work with in the production of new
species.
This blindness, no doubt, arose in some persons from the
ingrained idea of man's special creation, at all events, and that
it was almost impious to suppose that these variations could
have had anything to do with his development from some
lower forms. But among naturalists the idea long prevailed,
as it does still to some extent, that in a state of nature there
is little variation. Yet here, too, they might have found a
clue in the fact, so often quoted, that a shepherd knows every
individual sheep in his flock, and the huntsman every dog in
his well-matched pack of hounds, and this notwithstanding
that in both cases these animals are selected breeds in which
all large deviations from the type form are usually rejected.
Of late years, however, variations occurring in a state of
nature have been carefullv examined and measured, and it is
to some of these that w^e will now appeal for the proof of ever-
present variation of the character and amount needed for the
production of new species and of every kind of adaptation by
means of natural selection or the survival of the fittest. Be-
110
THE WOKLD OF LIFE
fore giving examples of the variation of the higher animals
it will be advisable to show Avhat is meant bv the " law of
frequency " of variations which has been established by the
measurement of several thousands of men in various countries
of Europe. These when recorded by means of a diagram are
found to form a very regular curve, which becomes more and
more regular the larger are the numbers measured. The im-
portance of this is that when we have only small numbers of
animals to deal with, and we find great irregularity in their
diagrams, we are sure that if we had measurements of hun-
dreds or thousands the curves would be equally regular ; and
this has now been found to be the case.
The law alluded to is that the number of individuals show-
ing any particular amount of variation is in inverse proportion
to its departure from the mean value in the species. It is very
closely represented by a special curve called by mathematicians
the '' curve of eiTor," but for our purpose may be termed the
curve of frequency.
The diagram here given represents this curve obtained by^
mimm
^i^V:::^::::::.::..:...
Dwarfs. Average Men Giant*.
CURVE OF STATURE. (BRITISH).
Fig. 9.— Diagi-am of Heiglit of 2600 Men.
measuring the heights of a large number of men taken at
random.
The horizontal scale shows the heights given in feet and
inches, and the vertical scale the numbers measured of suc-
cessive heights. The central line through the highest point of
HEEEDITY, ViVEIATIOE" 117
the curve marks the average of the whole number measured,
there being in this case (though not always) very nearly
the same number of individuals above and below the mean
height.
The peculiarity of the curve is that it rises very slowly from
the height marking that of the shortest individual measured —
here a fraction above 4 feet 8 inches — then more and more
rapidly for about one-third of the height, then more rapidly
and nearly regularly to near the summit, when it bends in
rather abruptly to the mean height, and then descends in a
nearly corresponding curve as heights are above the average,
till it ends just short of 6 feet 8 inches.
By adding together the numbers on both sides of the curve
we find that in this particular group of 2600 men none were
quite so short as 4 feet 8 inches or quite so tall as 6 feet 8
inches. But in any other group of the same number the ex-
tremes might be a little more or less, perhaps a quarter of
an inch or rarely a whole inch. We should have to measure
a million, or even several millions, to get the average height
and the proportionate greatest and least heights ; and even then
we should not get near the absolute limits of our race, as we
know that at long intervals giants and dwarfs appear, differing
by many inches, or even by a foot, from all others living at
the time. But, omitting these rare occurrences, the measure-
ments of a few thousand among a fairly mixed population will
give us the mean height of the whole, very nearh^; as well
as the proportionate numbers of those of particular heights,
as, for example, at 5 feet 3 inches or 6 feet 3 inches. But
even the mean height does not remain the same if the mode
of life changes. It is certain that the larger proportion now
living in crowded cities than there were a century ago has
considerably dwarfed our population.
We will now give an example of variation in a wild
animal in order to show that man and the animals and plants
which he has domesticated or cultivated do not differ in this
respect from those existing in a state of nature.
118
THE WORLD OF LIFE
The diagram here given is formed from the measurements
of six separate portions of twenty male specimens of the Bob-
o'-link or Rice-bird (Dolichonyx oryzivorus)^ very common in
I^orth America. All were obtained in the same place on the
same day, so that there could be no suspicion of their being
Inches
6 i 2
g JO ]] 22 23 24 25 26 27 28 J9 20 5
1 2 3 4 5 6 7 3 9 lO 22 22 23 14 J3 16 27 28 29 20
Rice-hird ( Dolicho2iyX'Oryz2voras .J 30 Males
Fig. 10, — Diagram of Variation.
HEKEDITY, VAlUATiOiV 119
in anv way selected as especially variable. It is a little larger
than our yellow-hammer^ and is therefore of a convenient
size to be shown on a diagram of its actual dimensions, thus
giving a better notion of the amount of variation of the several
parts than if reduced to a smaller scale.
The vertical lines, numbered at top and bottom, 1-20, show
the measurements of the tw^enty specimens of this bird, and
the figures at the sides, 0-5, mark the inches. The specimens
are arranged in the order of length of body, shown by the
upper somewhat irregularly curved line of dots. This is seen
to vary from 4% inches to a little less than 5 inches. The
next lower line show^s the length of the wing of each specimen,
and we at once see the want of correspondence with that of
the body. ^o. 5, w^ith a quite short body, has the longest
wing of all; while No. 16, with a long body, has nearly the
shortest wing. The third line, showdng the tail-lengths, is
equally remarkable, for No. 6 shows the longest tail with quite
a short body, while No. 16, with one of the shortest tails, has
a long body; so that Nos. 6 and 16, measured in the usual way
to the end of the tail, would be found of exactly the same size,
though the one is really % inch shorter than the other.
The next three lines show the varying lengths of the tarsus
(commonly termed the leg), the middle toe, and the outer toe,
and they too show very distinct and often contrasted divergences
in proportion to their small total length. Thus Nos. 11 and 18
have nearly the shortest legs with large bodies. The middle
toe in 7 is as long as in 19 and 20, while the outer toe is
decidedly longer than in 19, and in 12 decidedly shorter than
in 2.
It is particularly important to note here that this remarkable
amount of variation occurs in only tw^enty birds taken at
random. But the species is one of the most populous in North
America, occurring in enormous flocks over the whole conti-
nent, from 54° N. lat. in summer, and migrating as far south
as Paraguay in winter. There must, therefore, be an average
population of (probably) hundreds of millions, giving a much
120 THE WORLD OF LIFE
greater range of variation, and an ever-present abundance of
variations of all the parts and organs of the species.
In my Darwinism (chapter iii.) I have given sixteen dia-
grams of variation, showing that it ocenrs to an approximately
equal extent in mammals and reptiles as well as in birds, and
in a large number of their parts and external organs; while
many examples of variation occur among the lower animals,
especially insects, and also to an amazing extent among plants.
During the last twenty years an enormous amount of work
has been done in the investigation of variation in all its phases
and complexities, and an excellent accoimt of these has been
given by Dr. H. M. Yernon in his Variation in Animals and
Plants, 1903 (International Scientific Series), to which my
readers are referred for fuller information, but a few of his
conclusions may be here given. He says :
" Every organism varies in respect of all its characters, what-
ever be their nature. The amount of this variation differs greatly,
but it is always present in a greater or less degree."
And again, referring to a diagram showing the variations of
a squirrel, he says:
" Variation of a similar nature — though of a varying degree —
is present in all organisms, to whatever class of the animal or
vegetable kingdom they belong."
Eef erring to the diagram of human stature at p. 116, it is
found that about half the whole number measured vary a little
more than 2 inches above or below the mean, or a little more
than 3 per cent of the mean height. This is termed the per-
centage of mean error, and Mr. Vernon gives us an interesting
table of the same percentage for different parts of the body
derived from very larg-e numbers of measurements of different
races of men. It is as follows : —
HEREDITY, VARIATION
121
Per cent.
Nose length 9.46
" breadth 7.57
'' height 15.2
Forehead height 10.4
Under-jaw length 4.81
Mouth bretidtJi 5.18
Per cent.
Head length 2.44
" breadth 2.78
Upper arm length G.50
Fore arm length 3.85
Upper leg length 5.00
Lower " 5.04
Foot length 5.92
Here we see that the different parts of the human body vary
more, proportionally, than does its whole height ; and we must
always remember that these variations are all, to a large extent,
independent of each other, just as we saw was the case with
those parts shown in the bird diagram.
Again Ave must lay stress upon the fact that every part of
every organism, outside or inside, important or insignificant,
is subject to a similar and often more pronounced amount of
variation, as numerous examples quoted in Mr. Vernon's book
amply prove. So that we are fully justified in accepting as a
demonstrated fact, that the whole structure of every organism,
in every stage of its growth or development, varies in its dif-
ferent individuals, each one in a somewhat different manner,
and to such a large extent as to afford the amplest store of
material for modification and development in any direction
that may be required.
This ever-present and all-pei"vading variability is probably
the most important of the contributory factors of evolution,
and must never for a single moment be lost sight of.
Powers of Increase of Plants and Animals
Of almost equal importance with ever-present variation is
the power which all organisms possess of reproducing their
kind so rapidly as to be able to take possession of any unoc-
cupied spaces around them, and in many cases to expel other
kinds by the vigour of their growth.
The rapidity of increase is most prominently seen among
vegetables. These are capable, not only of a fivefold nr ten-
fold annual increase, as am<^iii:- many of the higher animals,
122 THE WORLD OF LIFE
but one of many hundred or even thousandfold annually. A
full-grown oak or beech tree is often laden with fruit on every
branch, which must often reach 100,000, and sometimes per-
haps a million in number, each acorn or nut being capable,
under favourable conditions, of growing into a tree like its
parent. Our wild cherries, hawthorns, and many other trees,
are almost equally abundant fruit-bearers, but in all these cases
it is only rarely (in a state of nature) that any one seed grows
to a fruit-bearing size, because, all having a superabundance
of reproductive power, an equilibrium has been reached every-
where, and it is only when some vacancy occurs, as when a
tempest uproots or destroys a number of trees, or some diminu-
tion of grazing animals allows more seedlings than usual to
grow up, that any of the seeds of the various trees around
have a chance of sun'iving; and the most vigorous of these
wall fill up the various gaps that have been produced.
But it is among the herbaceous plants that perhaps even
gi'eater powers of increase exist. Where our common fox-glove
luxuriates we often see its tall spikes densely packed with
capsules, each crowded with hundreds of minute seeds, which
are scattered by the wind over the surrounding fields, but only
a few which are carried to especially favourable spots serve
to keep up the supply of plants. Kerncr, in his Xatural His-
tory of Plants, tells us that a crucifer, Sisymhrium Sophia,
has been found to produce on an average 730,000 seeds, so that
if vacant spaces of suitable land existed around it, one plant
might, in three years only, cover an area equal to 2000 times
that of the land-surface of the globe. A close ally of this,
Sisymhrium Irio, is said to have sprung up abundantly among
the ruins of London after the great fire of 1666. Yet it is
not a common plant, and is a doubtful native, only occurring
occasionallv in En2^1ish localities.
Turning to the animal kingdom, we still find the repro-
ductive powers always large and often enonnous. The slowest
breeding of all is the elephant, which is supposed to rear one
young one every 10 years ; but, as it lives to more than 100
HEEEDITY, VAEIATION 123
years, Darwin calculates, that in 750 years (a few mouients
only in the geological history of the earth) each pair wuiikl,
if all their offspring lived and bred, produce 19 millions of
elephants.
The smaller mammals and most birds increase much more
rapidly, as many of them produce two or more families every
year. The rabbit is one of the most rapid, and ^Ir. Kearton
calculates that, under the most favourable conditions, a single
pair might in 4 or 5 years increase to a million. Australia,
being favourable in climate, vegetation, and absence of ene-
mies, they have so multiplied as to become a nuisance and
almost a danger, and though their introduction was easy, it
has so far been found impossible to get rid of them.
When the general adaptation of an animal to its whole con-
ditions of life over a large area is favourable, an enormous
population can permanently maintain itself in the face of what
appear to be dangerous enemies. Two cases illustrate this, and
at the same time show how the presence of civilised man leads
to their rapid extinction.
In the eighteenth century the bison ranged over almost the
w^hole of temperate Xorth America, being abundant in Penn-
sylvania and Kentucky, as well as over the whole of the central
plains, while it sometimes extended to the coast of the Atlantic.
Within the memor)^ of living persons it abounded west of the
Mississippi in countless herds many miles in extent, as vividly
described by Catlin the painter, in the stories of Mayne Reid,
and in the narratives of numerous travellers and explorers.
The fact that such a large and rather clumsy animal should
under natural conditions have occupied so large an area in
such vast multitudes, is a sure proof that it had become so
perfectly adapted to its whole environment as to effectually
protect itself against the numerous enemies that inhabited the
same area. Those powerful members of the cat tribe, the
jaguar and the puma, would have been quite able to destroy
the bison had it not been protected by its social instinct and
high intelligence. The wolves which hunt in packs, and are
124
THE WOraD OF LIFE
equally po^verful and ferocious mth those of Europe, must
also have been most dangerous enemies; but the bisons always
associated in numerous herds, and were so well guarded by the
old males, that they apj^ear to have suffered little from these
animals. The immense shaggy covering to the head, neck,
Fig. 11. — The American Bison {Bos Americanus) .
and breast of the male buffaloes, together with their short,
powerful horns, were an almost perfect protection ; and we
must consider these animals to have constituted one of the
highest developments of the great tribe of herbivorous quadru-
peds.
The extension of railways over the whole country about the
middle of the century, and the fact that, as the herds dimin-
ished buffalo skins became more valuable, led to its rapid
extermination ; and at the present time only a small and d^\'in-
dling herd exists in the Yellowstone Park, and another in
north-western Canada.
Even more remarkable has been the disappearance of the
passenger pigeon (Ectopistcs migratoria), so called from its
great powers of flight and its migration in vast flocks all over
Xorth America. The population of this bird was almost in-
credibly great, as described by the American ornithologists
Audubon and Wilson in the early part of the nineteenth cen-
HEREDITY, VARIATIOX 125
tiiry. It inhabited the whole of the wooded parts of Xorth
America from Mexico, within the tropic?, to the northern
shores of Ilndson's Bay, and its former history is now tlie more
interesting, because it has already become a creature of the
past. In the American periodical. The Auk, of last year, is
the following note :
''The Passenger Pigeox — only One Pair left. — I have
taken a special interest in the remaining birds belonging to the
Milwaukee and Cincinnati flocks which have been in confinement
for many years. In my last remarks on the species (Auk, 1908,
p. 18) I stated that the remnants of these flocks then numbered
but seven birds, with little or no chance of further reproduction.
The number is now reduced to a single pair, and doubtless the
months are numbered when this noble bird must be recorded as
extinct. — Ruthven Deane, Chicago, 111.''
In view of the above statement it ^\i\\ be both interesting
and instructive to state briefly what were the facts as to the
numbers of these birds about a hundred years ago (1811).
Alexander Wilson gives the following account in his American
Ornithology :
" The roosting-places are always in the woods, and sometimes
occupy a large extent of forest. "When they have occupied one of
these places for some time tlie appearance it presents is surprising.
The ground is covered to the depth of several inches with their
dung; all the tender grass and underwood destroyed; the surface
strewed with large limbs of trees broken down by the weight of tlie
birds collecting one above another ; and the trees themselves for
thousands of acres killed as completely as if girdled with an axe.
The marks of their desolation remain for many years. When these
roosts are first discovered, the inhabitants from considerable dis-
tances visit them in the night, with guns, clubs, long poles, pots of
sulphur, and various other engines of destruction. In a few liours
they fill many sacks and load horses with them.
"The breeding-place differs from the roost in its greater extent.
In the western countries, viz., the States of Ohio. Kentucky, and
Indiana, these are genei-allv in backwoods, and often extend in
126 THE WORLD OF LIFE
neai'h^ a straight line across the country for a great distance. Not
far from Shelby villc;, in the State of Kentucky, about five years ago,
there was one of these breeding-places which stretched through the
woods in nearl}^ a north and south direction, was several miles in
breadth, and was said to be upwards of forty miles in extent. In
this tract almost everv tree was furnished with nests wherever the
branches could accommodate them. The pigeons made their first
appearance there about the 10th of April, and left it altogether
with their young before the 25th of May. As soon as the young
were fully grown, and before they left the nests, numerous parties
of the inhabitants from all parts of the adjacent country came with
wagons, axes, beds, cooking utensils, many of them accompanied by
the greater part of their families, and encamped for several days at
this immense nursery. Several of them informed me that the noise
was so great as to terrify their horses, and that it was difficult for
one person to hear another speak without bawling in his ear. The
ground was strewed wath broken limbs of trees, eggs, and young
squab pigeons, which had been precipitated from above, and on
which herds of hogs were fattening. Hawks, buzzards, and eagles
were sailing about in great numbers, and seizing the squabs from
the nests at pleasure, while from twenty feet upwards to the top
of the trees the view through the woods presented a perpetual tumult
of crowding and fluttering multitudes of pigeons, their wings roar-
ing like thunder, mingled with the frequent crash of fallen timber ;
for now the axe-men were at work, cutting down those trees that
seemed to be most crowded with nests, and contrived to fell them
in such a manner that in their descent they might bring down
several others, by which means the falling of one large tree some-
times produced 200 squabs, little inferior in size to the old ones
and almost one heap of fat. It was dangerous to walk under these
flying and fluttering millions from the frequent fall of large
branches, broken down by the weight of the multitudes above, and
which in their descent often destroyed numbers of the birds them-
selves, while the clothes of those traversing the woods were com-
pletely covered with the excrements of the pigeons.
" I passed for several miles through this same breeding-place,
where every tree was spotted with nests, the remains of those above
described. In manv instances I counted upwards of ninety nests
in a single tree; but the pigeons had abandoned this place for
HEREDITY, VAEIATIOK 127
another, sixty or eighty miles oIT, towards Green river, where they
were said at tliat time to he equally numerous. From the great
numbers that were continually passing over our heads to or from
that quarter, I had no doubt of the truth of this statement. The
mast had been chiefly consumed in Kentucky; and the pigeons,
every morning a little before sunrise, set out for the Indiana terri-
tory, the nearest part of which w^as about sixty miles distant.
Many of these returned before ten o'clock, and the great body
generally appeared on their return a little after noon. I had left
the public road to visit the remains of the breeding-place near
Shelbyville, and was traversing the woods with my gun, on my way
to Frankfort, when about ten o'clock, the pigeons which I had
observed flying the greater part of the morning northerly, began
to return in such immense numbers as I never before had witnessed.
Coming to an opening by the side of a creek called the Benson,
where I had a more uninterrupted view, I was astonished at their
appearance; they were flying with great steadiness and rapidity, at
a height beyond gunshot, in several strata deep, and so close to-
gether that, could shot have reached them one discharge could not
have failed bringing down several birds. From right to left as far
as the eye could reach, the breadth of this vast procession extended,
seeming everywhere equally crowded. Curious to determine how
long this appearance would continue, I took out my watch to note
the time, and sat down to observe them. It was then half-past one ;
I sat for more than an hour, but instead of a diminution of this
prodigious procession it seemed rather to increase, both in numbers
and rapidity, and anxious to reach Frankfort before night, I rose
and went on. About four o'clock in the afternoon I crossed
Kentucky river, at the town of Frankfort, at which time the living
torrent above my head seemed as numerous and extensive as ever.
Long after this I observed them in large bodies that continued to
pass for six or eight minutes, and these again were followed by
other detached bodies, all moving in the same south-east direction
till after six o'clock in the evening. The great breadth of front
which this mighty multitude preserved would seem to intimate a
corresponding breadth of their breeding-place, wdiich, by several
gentlemen w^ho had lately passed through part of it, was stated to
me as several miles."
128 THE WOr.LD OF LIFE
Wilson then gives a rongli calciilation of the probahle num-
bers of this great flight of pigeons, and comes to the conclusion
that its whole length was 240 miles, and that the number of
birds must have been considerably more than 2000 millions.
If each pigeon consumed only half a pint of food daily, the
quantity would amount to over IT millions of bushels daily.
Audubon, who went throu2;h the same country about twentv
7 ~ 1-1/
years later, confirms Wilson's account in every essential part ;
and the language of the former is so simple and restrained,
that there is evidently no attempt to exaggerate what he wit-
nessed and was informed of by many independent observers.
Waterton, with his usual scepticism as to the observations of
other naturalists, treats the whole narrative as gross exaggera-
tion or fabrication ; on which the late Professor Alfred Xewton
remarks, that the critic would probably have been less severe
had he known that, 150 years earlier, these pigeons so swarmed
and ravaged the colonists' crops near Montreal, that a bishop
of his own Church was constrained to exorcise them with holy
water as if they had been demons. Professor Xewton adds
that the rapid and sustained flight of these pigeons is as well
established as their former overwhelming abundance, birds hav-
ing been killed in the State of Xew York whose crops contained
undigested grains of rice that must have been not long before
plucked and swallowed in South Carolina or Georgia. The
passenger pigeon has several times been shot in Great Britain,
and Professor Xewton believes that some of these crossed the
Atlantic unassisted by man.
Considering the vast multitudes of these birds in a state of
nature, notwithstanding the variety of birds of prey in Xorth
America, together with its unequalled powers of flight, it must
be classed as one of the finest examples of what DarAvin termed
" dominant species," and may also be considered as the highest
development of the special type of bird-life manifested in the
order Columbse or Pigeons ; and it will doubtless, by future
generations of bird-lovers, be counted as a blot upon the boasted
civilisation of the nineteenth century that, in its mad greed
HEREDITY, VARIATION
129
for wealth, it should have so devastated a whole continent as
not to leave room in it for the continued existence of such
grand and beautiful life-fomis as the bison and passenger
pigeon.
Equally remarkable, perhaps, is the Norwegian lemming, a
little animal somewhat larger than our short-tailed field-mouse,
Fig. 12. — The Lemming {Myodes lemmus).
but with a tail only half an inch long. This creature is always
abundant in Lapland and northern Scandinavia, but only ex-
traordinarily so at long intervals, when favourable conditions
lead to its almost incredible multiplication. At intervals of
from ten to twenty-five years a great army of them appears,
which devours every green thing in its path. Great bands
descending from the highlands of Lapland and Finland march
in parallel lines about 3 feet apart, never turning aside, cross-
ing lakes, and rivers, and even eating through com and hay-
stacks when these cross their path. The following recent
130 THE WOELD OF LIFE
statement of the ascertained facts as to these strange migra-
tions — from the work on Mammals by the late Sir H. Flower
and E. Lydekker — will prove interesting:
" The -usual dwelling-place of the Lemmings is in the highlands
or fells of the great central mountain chain of Norway and Sweden.
South of the Arctic circle, they are, under ordinary circumstances,
exclusively confined to the plateaus covered with dwarf birch and
juniper above the conifer region, though in Tromso and Finmarken
they occur in all suitable places down to the level of the sea. The
nest is found under a tussock of dry grass or a stone, constructed of
dry straws and usually lined with hair. The number of young in
each nest is generally five, and at least two broods are produced
annually. Their food is entirely vegetable, especially grass roots
and stalks, shoots of the birch, reindeer-lichen and mosses, in search
of which they form in winter long galleries through the turf or
under the snow. They are restless, courageous, and pugnacious
little animals. AMien suddenly disturbed, instead of trying to es-
cape, they will sit upright, with their back against a stone or other
object, hissing or showing fight in a very determined manner.
(See Fig. 12.)
" The circumstance which has given more popular interest to
the Lemming than to a host of other species of the same order of
animals is that certain districts of the cultivated lands of iSTorway
and Sweden, where in ordinary circumstances they are quite un-
known, are occasionally and at very uncertain intervals, varying
from five to twent}^ or more years, literally overrun by an army of
these little creatures, which steadily and slowly advance, always in
the same direction, and regardless of all obstacles, swimming across
rivers and even lakes of several miles in breadth, and committing
considerable devastation on their line of march by the quantity of
food they consume. In their turn they are pursued and harassed
by a crowd of beasts and birds of prey, as bears, wolves, foxes, dogs,
wild cats, stoats, weasels, hawks, and owls, and are never spared by
man; even the domestic animals not usually predaceous, as cattle,
goats, and reindeer, are said to join in the destruction, stamping
them to the ground with their feet, and even eating their bodies.
Numbers also die from diseases apparently produced by overcrowd-
ing. None ever return by the course over which they have come.
HEEEDITY, VARIATION 131
and the onward march of the survivors never ceases until they reach
the sea, into which they plunge, and swimming outwards in the
same direction as before, perish in the waves. ... So extraor-
dinary was the sudden appearance of these vast bodies of Lem-
mings to the Norwegian peasants, that they supposed they must
have fallen from tiie clouds.
" The principal really ascertained facts regarding these migra-
tions seem to be as follows : When a combination of favourable
circumstances has occasioned a great increase in the numbers of
Lenmiings in their ordinary dwelling-places, a movement neces-
sarily occurs at the edge of the elevated plateau, and a migration
towards the low-lying land begins. The whole body slowly moves
forward, advancing in the same general direction in which they
started, but following more or less the course of the great valleys.
They only travel by night, and they also stay in congenial places
for weeks or months, so that, with unaccustomed abundance of
food, notwithstanding all the destructive influences to which they
are exposed, they multiply excessively during their journey, having
families still more numerous and more frequently than in their
usual homes. The progress may last from one to three years, ac-
cording to the route taken and the distance to be traversed until
the sea coast is reached, which, in a country so surrounded by
water as the Scandinavian peninsula, must be the ultimate goal of
such a Journey. This may be either the Atlantic or the Gulf of
Bothnia, according as the migration has commenced from the west
or east side of the elevated plateau. Those that finally perish in
the sea are only acting under the same blind impulse which has
led them previously to cross smaller pieces of water with safety."
The strange history of these small creatures, besides showing
the enormous powers of increase in various types of life, also
furnishes us with a fine example of adaptation to what would
be, to most animals, extremely adverse conditions — high
plateaus within or bordering on the Arctic circle, with its
intense cold, its long periods of darkness, buried in snow in
winter and with a scantv and stunted vegetation. Yet thev
appear to have a most enjoyable existence, and would evidently
be able to overrun and occupy a much larger extent of sim-
132 THE WORLD OF LIFE
ilarly inhospitable country did such exist in their vicinity;
while in more fertile lands, with a milder climate and more
luxuriant vegetation, they rapidly become extinct through dis-
ease or the attacks of enemies.
In Mr. W. II. Hudson's most interesting volume, A Nat-
uralist in La Plata, he gives an account of a very similar rapid
increase of field-mice, under extremely different conditions, in
the chapter entitled A Wave of Life. In a concluding pas-
sage he so clearly summarises the whole course of events that
I here extract it : —
" Cover and food without limit- enabled the mice to increase at
such an amazing rate, that the ordinary checks interposed by pred-
atory species were for a while inappreciable. But as the mice
increased so did their enemies. Insectivorous and other species
acquired the habits of owls and weasels, preying exclusively on
them; while to this an innumerable array of residents was shortly
added multitudes of wandering birds coming from distant regions.
'No sooner had the herbage perished, depriving the little victims of
their cover and food, than the effects of the war became apparent.
In autumn the earth so teemed with them that one could scarcely
walk anywhere without treading on mice ; while out of every hollow
weed-stalk lying on the ground dozens could be shaken; but so
rapidly had they been devoured by the trained army of persecutors
that in spring it was hard to find a survivor even in the barns and
houses. The fact that species tend to increase in a geometrical
ratio makes these great and sudden changes frequent in man}^ parts
of the earth; but it is not often that they present themselves so
vividly as in the foregoing instance, for here, scene after scene in
one of l^ature's silent, passionless tragedies, myriads of highly
organised beings rising into existence only to perish almost imme-
diately, scarcely a hard-pressed remnant surviving to continue the
species."
It may, however, be concluded that not thus are species
exterminated in any region that remains suitable for their
existence. Long before they approach extinction, the very
scarcity of them drives away, one after another, the crowd of
HEEEDITY, YAEIATION" 133
enemies whicli had been attracted by their inordinate num-
berSj till the former balance of life is restored, and the rapid
powers of increase of the sufferers soon restores them to their
normal population. It is against the adverse powers of inor-
ganic nature that speedy reproduction is such a safe-guard.
When fire or flood, droughts or volcanic outbursts have de-
stroyed animal life over wide areas, the few survivors on the
margin of the devastated area are able to keep pace with
renewed vegetation and again stock the land with its former
variety of living things.
The facts outlined in the present chapter, of abundant and
ever-present variability with enormous rapidity of increase,
furnish a sufficient reply to those ill-informed writers who still
keep up the parrot-cry that the Darwinian theory is insuffi-
cient to explain the formation of new species by survival of
the fittest.
They also serve to rule out of court, as hopelessly inefficient,
the modern theories of ^' mutation " and " mendelism,'' which
depend upon such comparatively rare phenomena as " sports ''
and abnormalities, and are, therefore, ludicrously inadequate
as substitutes for the Darwinian factors in the world-wide and
ever-acting processes of the preservation and continuous adap-
tation of all living things. The phenomena upon which these
theories are founded seem to me to be mere insifmificant bve-
products of heredity, and to be essentially rather self-destruc-
tive than preservative. They form one of nature's methods of
getting rid of abnormal and injurious variations. The per-
sistency of Mendelian characters is the veiy opposite of what
is needed amid the ever-changing conditions of nature.^
1 A critical examination of these theories is gjiven in Mr. G. Archdall
Reid's recent work, The Principles of Heredity. There is also a shorter and
more popular criticism in the Introduction to Professor E. B. Poiilton's
Essays on Evolution (1908).
CHAPTER VIII
ILLUSTRATIVE CASES OF NATURAL SELECTION AND ADAPTATION
We have now learnt something of the great features of the
^' world of life " whose origin, development, and meaning we
are seeking to comprehend ; we have been enabled to visualize
its enormous extent, its almost endless diversity of form, struc-
ture, and mode of existence; the vast population of the species
that compose it, especially those which we term common.
Further, we have seen something of the way in which large
numbers of species inhabit the same area intermingled to-
gether, which they are enabled to do by each being adapted
to some one station or particular kind of food which its peculiar
organisation enables it to utilise; each occupying, as it were,
a special place in the economy of nature.
We have also learnt something of the three great factors which
are essential for the gradual modification of species into new
and better adapted organisms — heredity, variation, and enor-
mous powers of increase, leading inevitably to a struggle for
existence, since of the many that are born only a few can
possibly survive. We are, therefore, now prepared to exam-
ine, so far as we are able, the exact method of Nature's work
in species-production.
One of the difficulties in the way of an acceptance of con-
tinuous evolution through variation and natural selection is,
that though variation may be fully admitted, and though great
changes of climate and some changes of land and sea have
occurred in the human period, these do not seem to have led
to the foraiation of new species, but only to the extinction,
or change in the distribution, of a few of them. But of late
years naturalists, having pretty well exhausted the well-defined
species of the best-known parts of the world — Europe and
134
CASES OF ADAPTATION 135
iN'ortli America — have j^aid more attention to varieties, and
especially to those characteristic of islands or other well-
marked and somewhat isolated districts.
Having been much struck, some forty years ago, by the fact
that two peculiar beetles are found in Lundy Island (in the
Bristol Channel), another in Shetland, while some peculiar
forms of butterflies and moths occurred in the Isle of ^Alan, I
thought it would be interesting to collect together and publish
lists of all the species or varieties of animals and plants whicli
had hitherto been found only in our Islands. This I attempted
when writing my Island Life in 1880 and several specialists
in various groups were kind enough to draw up lists for me.
These were revised and much increased in the second and third
editions; and in the latter (1902) they amounted to 5 birds,
14 fresh-water fishes, 179 lepidoptera, 71 beetles, 122 land
and fresh-water molluscs, and 86 flowering plants. It is inter-
esting to note that of these latter no less than 20 are found only
in Ireland, where the insular conditions of climate that may
be supposed to lead to modification are at a maximum. Xo
less than 20 species of our Mosses and 27 of our Ilepaticse are
also not found in Europe, though a few of them are (and others
may be) found in other parts of the world.
As there is no doubt that our islands were at no distant
period (in a geological sense) united to the continent, and
that since their separation they must, through the influence
of the Gulf Stream penetrating around and among them, have
acquired a milder, moister, and a more uniform climate, it
seems quite probable that a considerable proportion of these
numerous local forms are actual modifications of the allied
continental forms due to adaptation to the changed conditions.
Since my book was published, an interesting addition to the
list of peculiar birds has been made by Dr. Ernst Ilartert, in
an article entitled On Birds represented in the British Isles,
by peculiar Forms. In this list, with MSS. additions up to
the end of 1909, Dr. Hartert enumerates no less than 21 spe-
cies, which have become more or less distinctly modified from
136 THE WOELD OF LIFE
their continental allies. These include a distinct crossbill from
the highlands of Scotland, all our British titmice, which seem
to be especially modifiable, and several others. The complete
list is as follows : —
1. Pyrrhula pyrrhula pileata British Bullfinch.
2. Turdus musicus clarkei " Song-Thrush.
3. Pratincola rubicola hibernaeus " Stonechat.
4. Garrulus glandarius riifitergum .... " Jay.
5. Loxia curvirostra scotica Scottish Crossbill.
6. Carduelis carduelis britannicus British Goldfinch.
7. Motacilla flava rayi Yellow Wagtail.
8. " alba lugubris Pied Wagtail.
9. Parus major newtoni British Great Titmouse.
10.
11.
12.
13.
14.
cieruleus obscurus " Blue Titmouse.
ater britannicus " Coal Titmouse.
palustris dresseri " Marsh Titmouse.
atricapillus kleinschmidti . . . . " Willow Titmouse,
cristatus scotica Scottish Crested Titmouse.
15. Aegithalus caudatus rosea British Long-tailed Titmouse.
16. Regulus regulus anglorum " Goldcrest.
17. Sitta europaea britannica " Nuthatch.
18. Certhia familiaris britannica " Tree-creeper.
19. Erithacus rubecula melophilus " Robin.
20. Troglodytes troglodytes pirtensis , . St. Kilda Wren.
21. Cinclus cinclus britannicus British Dipper.
22. Dendrocopus major anglicus " Great Spotted Woodpecker
23. " minor comminutus " Lesser Spotted Wood-
pecker.
24. Lagopus lagopus scoticus Bed Grouse.
This last has been generally treated as a well-marked species,
but Dr. Hartert considers it, with all the others, to be a sub-
species — a species in the making. It is certainly a very inter-
esting fact that so many of our familiar birds are found to
present constant differences from their continental allies.
Most of these differences are of colour only, but some diversity
of bulk and in the size of the bill indicate the commencement
of structural modification; and these various differences from
the nearest continental species in so many of our resident birds
seem inexplicable on any other theory than that they are adap-
tations to the slight but undoubted difference of climatical con-
ditions which characterise our islands.
CASES OF ADAPTATION 137
In confirmation of this view, a few cases have been recorded
in which nature has been caught, as it were, at work in the
actual formation of new species at the present time. The
first is that of the Porto Santo rabbits, carefully investigated
by Darwin. In the history of an early Spanish voyage it is
recorded that, a female rabbit having had a litter of young
on board, they were all turned loose on this small uninhabited
island near Madeira. This was about 1419, and from these
alone the island became fully stocked, and remains so still,
although the island is now fairly peopled. Darwin was able
to examine two of these rabbits preserved in spirits, three
others in brine, and two alive which had been in the Zoological
Gardens for four years. These seven specimens, though caught
at different times, closely resembled each other, they were all
full grown, yet they were very much smaller than English
wild rabbits, being little more than half the weight, and nearly
three inches less in length. Four skulls of the Porto Santo
rabbits diifered from those of English vdld rabbits in the supra-
orbital processes of the frontal bone being narrower; but they
differed considerably in colour, the upper surface being redder,
and the lower surface pale grey or lead colour instead of white ;
the upper surface of the tail, however, was reddish-brown in-
stead of blackish-grey as in all wild European rabbits, while
the tips of the ears had no black edging, as our rabbits always
have.
We have here a very remarkable series of differences in size,
colour, and even in the form of the skull ; while it was noticed
at the Zoological Gardens that they were unusually wild and
active, and also more nocturnal in their habits than common
wild rabbits. In this case, these rabbits would certainlv have
been described as a distinct species if they had been found
in some more remote country to which it was certain that they
had not been introduced by man.
Another example which shows nature at work, this time in
the actual process of " selection " of the better adapted indi-
viduals, occurred quite recently. In February 1898, at the
138 THE WORLD OE LIFE
Brown University, Providence, Rhode Island, after a very
severe storm of snow, sleet, and rain, 136 common sparrows
were found benumbed on the ground, and were collected and
brought to the Anatomical Laboratory. They were laid on
the floor of a warmed room to see if any of them were alive,
where after a short time 72 of them revived while 64 perished.
The happy thought occurred to Professor LI. C. Bumpus, that
here was an opportunity of discovering whether there were any
visible characters indicating why some of these birds, under
exactly similar conditions, w^ere destroyed while others sur-
vived. He therefore made a very minute and careful exami-
nation of all the birds, living and dead, with very interesting
results, of which the following is a summary:
(1) Sex. — About two- thirds were males, one-third females.
Of the former 51 lived, 36 died; of the latter 21 lived, 28
died, showing a decided superiority of the males in resisting
cold and wet.
(2) Size. — Here the comparison was made of male adult
birds, male young, and females, separately; in all three of
these groups those which died were larger than those which
sundved. The difference was not very great, but it was clearly
marked, and as it occurred in all three groups it could not
possibly be imputed to chance.
(3) Weight. — This gives the same result as in the last case,
the survivors being lighter than those w^hich died, by the con-
siderable proportion of one twenty-fifth.
(4) Length of the Sternum (breast-bone). — This character
gives a rather unexpected result, those birds which survived
having a decidedly longer sternum than those which perished.
The difference is about .013 (a little more than one-hundredth)
of the total length; but as the smaller birds on the whole
survived, these evidently had their sterna proportionally very
long. ]^ow the sternum is an indication of the size of the
pectoral muscles w^hich move the wings in flight. The sur-
viving birds therefore were those that could fly quickest and
longest, and this probably led to the more rapid production
CASES OF ADAPTATION 139
of animal heat. Another advantage would be, that these
muscles being larger proportionally there would be less ex-
posure of the internal organs to the extreme cold.
The result of this interesting experiment is almost conclu-
sive as to the reality of natural selection. In this case those
which actually survived one of nature's most common tests —
exposure to severe storms — and which must be presumed to
have been the '' fittest " at that particular time and place, were
found to differ in just such characters, and in such moderate
proportions as have been found to occur constantly in all the
commoner species of birds, as well as of all other animals. It
proves also that such small variations are, as Professor Lloyd
Morgan terms it, of " survival value," a fact which is con-
stantly denied on purely theoretical grounds.
It will perhaps make the subject a little clearer if I here
enumerate briefly the exact causes which must have been at
work in bringing about the changes in the rabbits of Porto
Santo during the four and a half centuries that had elapsed
from the time they were turned loose upon the island to the
period when Darwin obtained his specimens. The island has
an area of about 20 square miles ; it is very hilly, of volcanic
origin, with a dry climate and scanty vegetation. It is about
26 miles from Madeira, 400 from Africa, and 250 from the
Canary Islands. The powers of increase of rabbits being so
great, and the island being at that time uninhabited, they
would certainly in a very few years have increased to so great
a multitude as to consume all the available vegetation. As
they approached to these numbers, and were obliged to expose
themselves in the daily search for food, many birds of prey
from the larger island, and probably others from the Canaries
and from Africa — hawks, buzzards, falcons, and owls —
would flock to this hitherto desert island to feed upon them,
and would rapidly reduce their numbers.
Up to this time, perhaps not more than a dozen or twenty
years from their first introduction, they would have varied in
size and colour as do the common domesticated rabbits from
140 THE WOELD OF LIFE
which Darwin thinks they w^ere nndonbtedly derived. Their
numerous enemies would at first capture the larger, more bulky,
and slower-moving individuals, then the white or black speci-
mens, who would be more easily seen and pounced upon. This
process, continuously acting for a few generations, would result
in a smaller and more dusky-coloured race. The continuous
attack persisting, the size would be again reduced, and the most
agile and rapid in movement would alone survive. There-
after, the nocturnal habit would be acquired by the day-feeders
being almost exterminated, and owls would probably alone
remain as formidable enemies. Lastly, the extreme wildness,
sensitiveness to danger, perhaps to noise or movement of any
kind, would be developed, while the reduction of the supra-
orbital process may perhaps have been beneficial by reducing the
width of the head, and thus allowing them to enter small
holes in the rocks more rapidly; or it may possibly be con-
nected with the more nocturnal habits. We thus see that all
the changes that have occurred in this interesting animal have
no relation whatever to mere " isolation," which many writers
still persist in claiming as a vera causa of specific change, but
are all clearly traceable as the results of (1) rapid powers of
multiplication; (2) that small amount of variability which
we know" occurs in all such animals; and (3) rigid selection
through diurnal and nocturnal birds of prey, which we have
seen to play so large a part in keeping down the numbers of
the passenger pigeons in ISTorth America, the lemming in Scan-
dinavia, and the mice in La Plata.
The two cases now adduced, showing how nature actually
works in the production of slightly modified forms through
" variation " and ^^ survival of the fittest " will, I think, render
the process of species-formation sufficiently intelligible. Very
slight inorganic agencies have here been seen at work — in one
case a single severe storm, in the other a change to an isolated
habitat where slightly new conditions prevailed. But when
in the course of those periods when geological changes were
most actively at work, larger and more permanent climatic
CASES OF ADAPTATION 141
changes occurred, or when more marked diversities of soil and
vegetation, with exposure to more severe competition, were
brought about, those modifications of the environment ^vould
inevitably result in more marked and more varied adaptations
of form, structure, or habits, bringing about what we every-
where recognise as perfectly distinct species.
In the present work I do not propose to go further into this
matter, which has been treated with sufficient detail and with
copious illustrations in my Darwinism and other works, as
well as in Darwin's classical volumes. The Origin of Species
and Animals, and Plants under Domestication. I will there-
fore now proceed to an account of some of those broader aspects
of adaptation in the organic world, which, so far as I am aware,
have hitherto received little attention.
Some Aspects of Organic Adaptation
Though such a very obvious fact, it is not always kept in
mind, that the entire animal world, in all its myriad manifes-
tations, from the worm in the soil to the elephant in the forest,
from the blind fishes of the ocean depths to the soaring sky-
lark, depends absolutely on the equally vast and varied vege-
table world for its very existence. It is also tolerably clear,
though not quite so conclusively proved, that it is on the over-
whelming variety of plant species, to which we have already
called attention, that the corresponding variety of animal spe-
cies, especially in the insect tribes, has been rendered possible.
This will perhaps be better seen by a reference to one of
the best-known cases of general adaptation, which, because so
common and obvious, is often overlooked or misunderstood.
All lovers of a garden are apt to regard as an unmitigated evil
those swarms of insects which attack their plants in spring, and
in recurrent bad years become a serious nuisance and commit
widespread devastation. At one time the buds or leaves of
their fruit trees swarm with various kinds of caterpillars, while
at others even the oak trees are so denuded of their leaves as
to become an eyesore in the landscape. Many of our common
142 THE WOKLD OF LIFE
vegetables, and even the grass on our lawns, are in some sea-
sons destroyed bj swarms of wire-worms which feed on their
roots. Turnips, radishes, and allied plants are attacked by
the turnip-fly, a small jumping beetle whose larva lives in the
leaf itself, and w^hich often swarms in millions. Then there
are the a2:>hides and froghoppers on our roses and other shrubs
or flowers, and grubs which attack our apples, our carrots,
and most other crops; and all these the gardener usually re-
gards under the general term " blight," as a serious blot on
the face of nature, and wonders why such harmful creatures
were permitted to exist.
Most professional gardeners would be rather surprised to
hear that all these insect-pests are an essential part of the world
of life ; that their destruction would be disastrous ; and that
without them some of the most beautiful and enjoyable of the
living things around us would be either seriously diminished
in numbers or totally destroyed. He might also be informed
that he himself is a chief cause of the very evil he complains
of, because, by growing the plants the insect-pests feed upon
in large quantities, he provides for them a superabundance of
food, and enables them to increase much more rapidly than
they would do under natural conditions.
Let us now consider what happens over our whole country
in each recurring spring. At that delightful season our gar-
dens and hedgerows, our orchards, woods, and copses are
thronged with feathered songsters, resident and migratory, en-
gaged every hour of the day in building their nests, hatching
their eggs, or feeding and guarding their helpless offspring.
A considerable proportion of these — thrushes, warblers, tits,
finches, and many others — are so prolific that they have two
or three, sometimes even more, families every year, so that
the young birds reared annually by each pair varies from four
or five up to ten or twenty, or even more.
Now, when we consider that the parents of these, to the
number of perhaps fifty species or more, are all common birds,
which exist in our islands in numbers amounting to many
CASES OF ADAPTATION 143
raillions each, we can partially realise the enormous quantity
of insect-food, required to rear perhaps five or ten times that
number of young birds from the egg up to full growth. Al-
most all of the young of the smaller birds, even when their
parents are seed-eaters, absolutely require soft insect-food, such
as caterpillars and grubs of various sorts, small worms, or such
perfect insects as small spiders, gnats, flies, etc., which alone
supjoly sufficient nourishment in a condensed and easily digest-
ible form.
Many enthusiastic observers, by means of hiding-places near
the nests or by the use of field-glasses, have closely watched the
whole process of feeding young birds, for hours or even for
w^hole davs, and the results are extremelv instructive. The
chiff-chaff, for example, feeds its young on small grubs ex-
tracted from buds, small caterpillars, aphides, gnats, and small
flies of various kinds ; in a nest with five young, the hen-bird
fed them almost all day from early morning to sunset, bringing
mouthfuls of food at an average four times in five minutes.
This may no doubt be taken as typical of a number of the
smaller warblers and allied birds.
Blue tits, with a larger family, worked continuously for
sixteen hours a day at midsummer, bringing about two thou-
sand caterpillars to the ravenous young birds, who, taking the
average at 10 (and they sometimes have 16) would swallow
200 each in the day. A pair of marsh tits were observed to
feed their young entirely with small green caterpillars, and
in one case made 475 journeys with food in seventeen hours.
A gold-crest with eight young brought them food 16 times
in an hour for sixteen hours a day. A wren fed its young
278 times in a day. Even the common house-sparrow, itself
a typical seed-eater, feeds its young on caterpillars or on small
insects which it catches on the wins:. A flvcatcher was ob-
served to sit on a dead branch of an ash tree near her nest,
whence by short flights she cauglit small flies, etc., on the
wing, bringing a mouthful to her young every two to five min-
utes.
144 THE WORLD OF LIFE
As every schoolboy knows, the number of nests is very great
to those who know how to look for them, some being found in
almost every wood, copse, or hedgerow. As examples, in a
small copse in Herts, nine different species of birds had nests
with young, all within 50 yards of each other. In another
case, nests of a tit, a flycatcher, and a wood-wren were found
within 10 to 15 yards of each other. In the case of many
small birds the whole period, from hatching the eggs to that
of the young leaving the nest is only two weeks, but swifts
require from a month to six weeks.
It must be remembered that the birds carefully clean out
the nest after every meal, and in wet or very chilly weather
carefully protect their young, and as they must also procure
food for themselves, it is evident that their labours at this
time are really prodigious. And this vast destruction of in-
sect-life goes on unchecked for several months together, and
the supply never seems to fail. When the parent birds leave
the nest in search of food for their young, they may be seen
to fly to some adjacent bush or branch of a tree, hop rapidly
about it, and then perhaps fly off to another, having apparently
decided that the first one had already been nearly exhausted.
But in the few minutes of their absence they are always able
to fill their mouths with small caterpillars, flics, grubs, etc.,
and return to the nest, not only from morning to night on one
day, but the same day after day, for at least a fortnight and
often much longer, till their first brood is fully fledged and
able to provide for themselves. But unless the numbers of
insects and their larvse were enormous, and were increased
day by day by fresh hatchings from the egg as fast as they
were devoured, hosts of these young birds would perish of
hunger and cold. For if the parents had to range far away
from their nests, and could not find the necessary supply so
quickly as they do, the young birds would be subject to attack
from some of their numerous enemies, would suffer from cold
or wet, and as they grew older would often, in their frantic
CASES OF ADAPTATIOX 145
struggles with each other, fall out of the nest and quickly
perish.
What wonderful perfection of the senses must there be in
these various parent birds; what acuteness of vision or of
hearing; what rapidity of motion, and what powerful instinct
of jDarental love, enabling them to keep up this high-pressure
search for food, and of watchfulness of their nests and j^oung,
on the continuance of which, and its unfailing success, the
very existence of those young and the continuance of the race
depends. But all this perfect adaptation in the parent birds
would be of no avail unless the insect tribes, on which alone
most of them are obliged to depend, were as varied, as abun-
dant, and as omnipresent as they actually are ; and also imless
vegetation were so luxuriant and abundant in its growth and
so varied in its character, that it can always supply ample food
for the insects without suffering any great or permanent injury
to the individual plants, much less to any of the species.
By such considerations as these we learn that what we call
insect-pests, when they are a little more abundant than usual
in our gardens and orchards, do not exist for themselves alone
as an apparently superfluous and otherwise useless part of the
great world of life, but are, and must always have been through-
out long past geological ages, absolutely essential for the origina-
tion and subsequent development of the most wonderful,
delightful, and beautiful of all the living things around us —
our garden friends and household pets, and sweet singers of
the woods and fields. Without the myriad swarms of insects
everywhere devouring a portion of the new and luxuriant vege-
tation, the nightingale and the lark, the wren, the redbreast,
and the fairy-like tits and goldcrests might never have come
into existence, and if the supply failed would now disappear
for ever!
The Uses of Mosquitoes
If now we go beyond our OAvn country and see how birds
fare in distant lands, we find the key to many of the secrets
146 THE WORLD OF LIFE
of bird-life in the greater or less abundance of insects which
supply them with food at the critical season of their lives
when they have to supply daily and hourly food to their newly-
hatched broods. Amid all the infinite variety of the insect
world there is probably no one order which supplies such an
enormous quantity of food to birds and other creatures as the
two-winged flies (Diptera) whose larvx are the maggots which
quickly devour all kinds of dead beasts and birds, as well as
all kinds of putrefying animal matter ; but in the perfect state
these insects abound in such swarms as also to supply food to
whole groups of fly-catching birds. And among these no well-
marked and very restricted group is at once so hateful to
mankind and so delightful to birds as the mosquitoes. It is
commonly supposed that these particular insect-pests are more
especially tropical; but though they are no doubt very abun-
dant in many parts of the tropics, yet their fullest develop-
ment is to be found in the icy plains of the Far Xorth, espe-
cially within the Arctic circle both in the Eastern and Western
hemispheres.
Sir William Butler in his w^orks — The Wild Lone Land,
and others on Arctic and sub-Arctic Xorth America — de-
scribes them as often swarming in such abundance as to com-
pletely obscure the sun like a dense thundercloud ; and they
furnish abundant material for the wildly exaggerated stories
in which Americans delight — such as the serious statement
that they can pierce through the thickest cow-hide boots, and
that an Irishman, seeking protection from them by covering
his head with a copper kettle, they pierced it in such countless
numbers that their combined strength enabled them to fly away
with it!
Our best and most instructive writer on the wonderful bird-
migrations to the Arctic regions is the late Mr. Henry See-
bohm, who spent two seasons there, one in the north-east of
Russia, at Ust-Zylma, and at the mouth of the Petchora River,
far within the Arctic circle; and another in [N'orthern Siberia,
at the mouth of the Yenesay River. He tells us, that —
CASES OF xiDAPTxiTIOX
147
" Birds go to the Arctic regions to breed^ not by thousands but
by millions. The cause of this migration is to be found in the
lavish prodigality with which Nature has provided food. Seed or
Fig.
13.—
Sh
oo t
ing
Wild
Geese
on
the
Pet-
chora
River
at
Ust-
Zylma
(May
14
, 18
75).
fruit-eating birds find an immediate and abundant supply of cran-
berries^ crowberries, and other ground fruit, which have remained
frozen during the long winter, and are accessible the moment the
snow has melted, while insect-eating birds have only to open their
mouths to fill them with mosquitoes/' ^
Among the larger birds that come early to "these regions
to breed are two species of wild swans and the bean goose.
So early as 10th May they began to arrive, passing over Ust-
Zylma (Lat. G6^ N.) in flocks, where, by constiiicting a shelter,
Mr. Seebohm was able to shoot one. Even these large birds
find ample food on the tundra to breed there ; for just before
leaving the country, wdien near the mouth of the Petchora
1 Siberia in Europe, p. 296.
148
THE WORLD OF LIFE
Eiver, he saw them returning southward with their young.
He writes :
" I had not gone more than a mile when I heard the cackle of
geese ; a bend of the river's bed gave me an opportunity of stalking
them, and when I came within sight I beheld an extraordinary and
interesting scene. One hundred, at least, old geese, and quite as
Fig. 14. — Geese Moulting as they migrate South over the Tundra (July
and August ) .
many young ones, perhaps twice or even thrice that number, were
marching like a regiment of soldiers. The vanguard, consisting of
old birds, was half-way across the stream, the rear, composed
principally of goslings, was running down the steep bank towards
the water's edge as fast as their young legs could carry them. Both
banks of the river where the geese had doubtless been feeding,
were strewn with feathers, and in five minutes I picked up a
handful of quills. The flock was evidently migrating to the
interior of the tundra, moulting as it went along."
This species retires southwards before the winter, and visits
us every year in September or October being especially abun-
CASES OF ADAPTATIO:^
149
dant in Ireland, where it
is said to be found in
every bog and marsh.
On the Siberian tundra
it no doubt feeds largely
on the abundant berries,
but also, of course, on
the food it finds in
swamps and river-mar-
gms.
Coming back to our
more special subject of
the mosquitoes, Mr. See-
bohm writes as follows.
After describing some of
his early excursions after
birds or their nests he
adds:
Fig. 15. — Mr. Seebohm in his Mosquito
Veil.
" That day (June 2nd) I recorded in my journal, with many
groans, the arrival of the mosquitoes. Horrid-looking beasts, with
bodies a third of an inch long, monsters, the Culex damnabilis of
Eae, with proboscis infernali veneno inunita. I foresaw that we
should have opportunities enough to study the natural history of
these blood-thirsty creatures to our heart's discontent."
About a month later he writes when searching for eggs,
properly identified :
" Doubtless the proper thing to have done would have been to
lie down and watch the birds on to their nests; but to become tlie
nucleus of a vast nebula of mosquitoes is so tormenting to the
nerves, that we soon came to the conclusion that the birds had not
begun to breed, and that it was no use martyrising ourselves to find
their eggs. The mosquitoes were simply a plague. Our hats were
covered with them; they swarmed upon our veils; they lined with
a fringe the branches of the dwarf birches and willows; they cov-
ered the tundra with a mist."
150 THE WORLD OF LIFE
But this was quite at the beginning of the season, and he
adds:
" We were told that this pest of mosquitoes was nothing as yet
to what it would become later. ' Wait a while/ said our Job's
comforter, ' and you will not be able to see each other at twenty
"^mmi
Fig. 16. — Messrs. Seebohm and Harvie-Brown watching Grey Plover
through a Cloud of Mosquitoes.
paces distance; you will not be able to aim with your gun, for the
moment you raise your barrel half-a-dozen regiments of mosquitoes
will rise between you and the sight.' ''
And Mr. Seebohm described how he Avas protected by india-
rabber boots and cavalrv 2:auntlets, and a carefully constructed
cage over his head, without which he never dare go out on
the tundra (see Fig. 15).
Xow this Arctic country, beyond the limit of forests and
stretching to the polar ocean, ^vhich is buried for eight or nine
months under six feet thick of snow^, is yet, during its short
summer, a very paradise for birds of all kinds, which flock to
it from all over Europe and Central Asia in order to breed
and to rear their young; and it is very largely, and for many
species almost exclusively, this very abundance of mosquitoes
and their larvae that is the chief attraction. In Mr. Seebohm's
works, already quoted, and in his fine volume on the Geo-
CASES OF ADAPTATiOxX 151
graphical Distribution of the Plovers and allied birds, he gives
a most graphic account of this country and of the birds flock-
ing to it, which is worth quoting, as few people have any ade-
quate idea of what the greater part of the iirctic regions really
are in summer. After describing its extent and boundaries,
he says:
" I have called this district a paradise, and so it is for two
or three months of the year. Nowhere else in the whole world can
you find such an abundance of animal and vegetable life, brilliant
flowers, birds both of gay plumage and melodious of song, where
perpetual day smiles on sea and river and lake. For eight months
or more (according to the latitude) every trace of vegetable life is
completely hidden under a thick blanket which absolutely covers
every plant and bush. Far as the eye can reach, in every direction
nothing is to be seen but an interminable, undulating plain of white
snow."
Then after describing the few animals that live there even
during the wunter, and the strange phenomenon in May of
continuous day and almost perpetual sunshine, at midday hot
enough to blister the skin, yet still apparently in mid-winter
so far as the snow is concerned, he goes on to describe what
there takes place:
" The disc of snow surrounding the North Pole at the end of
May extends for about two thousand miles in every direction where
land exists, and is melting away on its circumference at the rate
of about four miles an hour, and as it takes a week or more to melt,
it is in process of being melted for a belt of several hundred miles
wide round the circumference. This belt is crowded with migratoiv
birds eager to push forwards to their breeding grounds — hurrying
on over the melting snow so long as the south wind makes bare
places soft enough to feed on, but perpetually being driven back
by the north wind, which locks up their food in its ice-chest.
. . . In watching the sudden arrival of summer on the Arctic
circle, both in the valley of the Petchora, in East Eussia, and in
the valley of the Yenesay, in Central Siberia, I was impressed with
the fact that the influence of the sun was nearly nothing, while
152
THE WOKLD OF LIFE
that of the south wind was almost everything. The great annual
battle between summer and winter in these regions is the one event
of the year: it only lasts a fortnight, during which a cold winter
is transformed into a hot sunmier."
He then gives a most interesting account of the breaking up
of the ice on the great north-flowing rivers till they become
roaring floods of muddy water, crowded with lumps of melted
ice of all shapes and sizes. On the 20th May he had just
crossed the Petchora to Ust-Zylma, over ice which was already
cracking.
" It was past midnight, and at any moment the crash might
come. Cracks running for miles, with a noise like distant thunder,
Fig. 17. — loe Breaking up on the
Petchora River.
warned us that a mighty power was all but upon us, a force which
seemed to impress the mind with a greater sense of power than
even the crushing weight of water at Niagara, a force which breaks
up the ice more than a mile wide, at least tliree feet thick, and
weighted with another three feet of snow, at tlie rate of a hundred
CASES OF ADAPTATIO]^
153
miles in twenty-four hours. . . . We slept for a couple of
hours, when, looking out of the window, we found that the crash
had come; the mighty river, Petchora, was a field of pack-ice and
ice-floes marching past towards the sea at the rate of six miles an
hour. We ran out on to the banks to find half the inliabitants of
Ust-Zylma watching the impressive scene.''
A week later he writes :
" Winter is finally vanquished for the year, and the fragments of
his beaten army are compelled to retreat to the triumphant music
Fig. 18. — Midsummer on the Tundra, at the Mouth of the Petchora River.
of thousands of song-birds, amidst the waving of green leaves and
the illumination of gay flowers of every hue. The transformation
is perfect. In a fortnight the endless waves of monotonous white
snow have vanished, and between the northern limit of forest growtli
and the shores of the Polar basin smiles a fairy-land, full of the
most delightful little lakes and tarns, where phalaropes swim about
amongst ducks and geese and swans, and upon whose margins stints
and sandpipers trip over the moss and the stranded pond-weeds,
feeding upon the larvae of mosquitoes, or on the fermenting frozen
fruit of last year's autumn.
154
THE WORLD OF LIFE
" It is incredible how rapidly the transformation is completed.
Twelve hours after the snow had melted the wood-anemone was in
flower, and twenty-four hours after the yellow flowers of the marsh-
marigold opened. In a short time the country looked like an
English garden run wild. On the Arctic Circle wild onions, wild
rhubarb, pansies, Jacob's ladder, purple anemones, dwarf roses, and
a hundred other flowers made the country quite gay ; whilst on the
tundras wild-fruits of various kinds — crowberry, cranberry, cloud-
berry, arctic strawberry — were blended with reindeer-moss and
Fig. 19. — Sudden Arrival of Birds in the Arctic Regions at the End of May.
other lichens, together with the most characteristic flowers of an
Alpine flora — gentians, saxifrages, forget-me-nots, pinks, monks-
hoods (both blue and yellow), and sheets of the Silene acauUs,
with its deep-red flowers. The Alpine rhododendron was replaced
by a somewhat similar shrub. Ledum palustre; but the flora, on
the whole, was like that of the Engadine brought down to the level
of the sea.
" Although the first rush of migratory birds across the Arctic
Circle was almost bewildering, every piece of open water and every
patch of bare ground swarming with them, a new species on an
average arriving every two hours for several days, the period of
CASES OF ADAPTATION 155
migration lasted more than a month. A^ery little migration was
observable till the last week in May, but during the next fortnight
the migration was prodigious. In additions to enormous numbers
of passerine birds, countless flocks of geese, swans, and ducks ar-
rived, together with a great many gulls, terns, and birds of prey.
During the next fortnight, from the 5th to the 19th of June, fresh
species of passerine birds continued to arrive, and the main migra-
tion of the great plover family took place."
One of the objects of Mr. Seebohm's journey to the Arctic
regions was to obtain authentic eggs and nests of the grey
plover. He found several, after long search. They were all
situated in depressions on a slight ridge among black bog-lakes,
and each had three or four eggs. The charming little i)icture
on the next page shows both nest, eggs, and young birds.
In order to ascertain approximately how many species of
birds visit the Arctic regions in the summer breeding season,
I have made rough lists of all those enumerated by Mr.
Seebohm in his two books, Siberia in Europe and Siberia in
Asia, and find that they amount to 160 species. This is very
nearly equal to the whole number of resident and migratory
birds which breed in our own country (about ISO) ; but they
cannot be more than a portion of the species that actually
migrate to the Arctic lands, as they were the result of two
visits only of about a couple of months each, and only two very
limited areas were explored. My friend, Mr. II. E. Dresser,
who also knows these regions personally and has made a special
study of their birds, has been so good as to make an enumera-
tion of all the birds known to breed in the Arctic regions
of Europe and Asia, and he finds it to be land birds 81) species,
waders and aquatics 84 species, equal to 173 in alL Consider-
ing how vast is the extent of the country, and how few ornithol-
ogists visit it, we may put the total number at at least ISO,
and possibly even 200 species.
The great accumulation of bird-life is, however, vividly pic-
tured by Mr. Seebohm, and it is clear from all that he says —
as well as bv what he does not sav — that the vast hordes of
156
THE WORLD OF LIFE
mosquitoes must be the chief support of the innumerable mil-
lions of young birds which have to be fed here, both passerine
and Avading birds. Of the former more than eighty species
are named, including seven buntings, four tits, two grosbeaks,
Fig. 20. — Grey Plover's Nest and Young {8quatarola helvetica).
six pipits, eleven warblers, five wagtails, two sparrows, three
woodpeckers, the beautiful Avaxwing, and a host of others,
many of which are among our common birds. What a delight
to them all must be this mish northward into a land of per-
petual daylight, swarming with the most nutritious food, fruits
and berries for the parents, inexhaustible clouds of mosquitoes
CASES OF ADAPTATION 157
— which Mr. Seebohm tells us are an especially large kind
with bodies a third of an inch long — and the equal myriads
of their larvse in every little pond or water-hole, as well as
quantities of larger worms and larva'. The extreme discom-
forts as well as the cost of a journey to these far northern
lands are so great that very few bird- or insect-collectors vi>ir
them, and it is not easy to obtain direct and accurate obser-
vations as to the actual part played by the myriad swarms of
mosquitoes in attracting birds from almost every part of tlio
northern hemisphere to go and breed there. Mr. H. 3^].
Dresser, who has made a special study of Palnearctic birds and
their eggs, has, however, obtained for me some very interesting
information. He writes:
" Colonel Feilden tells me that the young of the knot are fed
chiefly on the larvae of mosquitoes."
He has also sent me a copy of the following interesting letter
from an American ornithological correspondent, Mr. E. T.
Seton : —
" In reply to your recent favour I beg to say, that, in my
forthcoming book on a canoe journey of 2000 miles which I made
to the Arctic regions in 1907, I am setting forth at great length the
numbers, virulence, and distribution of the mosquitoes, together
with observations on those creatures which are immune from their
attacks. ... I should say that the night-hawk (Chordeiles
virginianus) is the most active enemy of this insect, feeding on it
during the whole season. On one occasion T took over 100
mosquitoes from the throat of one of these night-hawks, that was
carrying them home to feed its young. Many similar observations
have been recorded. Next in importance would come the broad-
billed flycatchers of the American group Tyrannidae, and the more
abundant though smaller species of the Mniotiltidse. All of these
I have seen feeding on the adult mosquitoes. Doubtless all of our
thrushes do the same, although I do not recall any positive records.
We are very safe, I take it, in cataloguing all of our small birds
as enemies of the mosquitoes in the adult form. The various
small wading birds, and the small ducks and grebes, are believed
158 THE WORLD OF LIFE
to prey on the larval mosquitoes ; but doubtless it is the insects and
small fish that are to be credited with the principal destruction in
this stage."
From his personal observations Mr. Dresser says:
" I believe that most of the waders feed their young on them
(mosquitoes) in the high north. In north Finland and Lapland
I found the small birds (warblers, swallows, etc.) feeding on
mosquitoes, and the snow bunting fed its young on them."
There is, therefore, a concensus of evidence as to the pre-
eminent attraction afforded by these insects to almost all birds
which breed in the Arctic regions.
The beautiful view on the opposite page gives us an idea
of the appearance of the upland tundra along the shores of
the Arctic Ocean. Here the southern slopes of the low hills
are the first to be free from snow, and afford an abundant
supply of last year's berries to the earliest migrants, as well
as a variety of animal food for aquatic birds on the adjacent
sea-shores in favourable situations.
The combined physical and emotional enjoyment in this
birds' paradise, during the whole of the Arctic summer, for
so large a number of species of birds and in such enormous
multitudes, is probably unequalled in any other part of the
world; and we have the satisfaction of knowing that it is
perhaps the only example of Nature's short-lived but annual
pleasure-gardens which will not be destroyed or rendered
hideous by the destructiveness and greed of civilised man.
When much of the beauty and luxuriance of nature has been
banished from milder regions, these inhospitable Arctic lands
will long remain in their wild luxuriance of summer beauty,
where those who trulv love nature wdll be able to witness one
of the most wonderful illustrations of the mvriad forms and
complex ada23tations which the world of life presents to us.
It is a significant feature of this adaptation, that of all
the higgler forms of life birds are the most completely pro-
tected from the blood-sucking and iiTitation of mosquitoes.
CASES OF ADAPTATIO]S[
159
Every imrt of the body is protected either with a dense mass
of phimage, or by a homy integument on the bill and feet,
so that they are probably quite undisturbed while enjoying
the super-abundant feast nature has spread for them in those
remote and usually repellent lands. We may conclude, there-
fore, that it is to the two special features of these Arctic
Fig. 21.— The Higher Tundra.
Stanavialachta at mouth of the Petchora River (N. Lat. 69°),
tundras — their abundant berries preserved during the winter
in a natural ice-house, and the myriad clouds of mosquitoes
and their larvge — that we owe the very existence of a consid-
erable proportion of the bird-life in the northern hemisphere.
The Origin of Bird-migration
These vast Arctic plains even in Tertiary times when
climates were milder, would, owing to the long winter nights,
have always been snow-covered during several months in winter
although its melting might have been earlier and the sunnner
somewhat longer ; there can be little doubt that the short sum-
160 THE WORLD OF LIFE
mer with its perpetual sunshine was equally favourable to the
production of a super-abundance of vegetable and insect food
very similar to what now exists there, and in this fact, we
find a very complete explanation of how bird-migration came
about. Abundance of food suitable for both parents and
young at the season of breeding, would inevitably attract birds
of all kinds from more southern lands, especially as the whole
area would necessarily have no permanent residents or very
few, but would, each recurring season, be an altogether new
and unoccupied but most fertile country, to be reached, from
any part of the north temperate lands, by merely following
up the melting snow. And as, a few months later, the myriads
of young birds in addition to their parents were driven south
by the oncoming of the cold and darkness, they would find
it necessary to travel farther and farther southward, and would
again find their way north when the proper season arrived.
There would always be a considerable niunber of the old and
experienced birds to show the way; and as, with increasing
severity of the seasons, the area of the snow-covered plains
would extend, and their capacity for feeding both old and
young would be increased ; there would at last be brought about
that marv^ellous rush of the migrating flocks which Mr.
Seebohm has so vividly described.
Before quitting the subject of migration, on which Mr.
Seebohm's observations throw so much light, I will shortly
describe the most wonderful exhibition of migration-phenom-
ena in the world — that of the small island of Heligoland,
40 miles off the mouth of the Elbe in about the same lati-
tude as Scarborough. Most of the migratory birds from
Scandinavia and xlrtic Europe pass along the coasts of the
German Ocean, and the lighthouse on Heligoland serves as
a guide, and the island itself as a resting-place during bad
weather. Mr. Seebohm's account of what he witnessed in
the island, during nearly a month spent there in September
to October 1875 (in chapter xx. of his Siberia in Euroj)e)
is most interesting; and I refer to it here chiefly for the
OASES OF ADAPTATION 161
sake of iDointing out a very important error as to the cause
of a very singular fact recorded there, by Herr Gatke, who
for fifty years, observed and registered the migrations both
in spring and autumn, with great accuracy, and formed a
collection of birds there, perhaps more extensive than could
be made at any other station in Europe. The fact observed
was, that, during the autumn migration, as regards many
of the most abundant species, the young birds of the year,
that is, those that had been hatched in the far north in the
preceding June or July, and who w^ere, therefore, only about
three or four months old, arrived in Heligoland earliest and
alone, the parent birds appearing a week or two later. This
is the fact. It has been observed on Heligoland for half a
century; every resident on the island knows it, and ]\Ir.
Seebohm declares that there can be no doubt whatever about
it. The inference from this fact (dravni by Herr Gatke and
all the Heligolanders, and apparently accepted by almost all
European ornithologists) is, that these young birds start on
their migration alone, and before their parents, and this not
rarely or accidentally but every year — and they believe also
that this is a fact, one of the most mysterious of the facts
of migration. Neither Mr. Seebohm nor Professor Lloyd
Morgan (in his Habit and Instinct) express any doubts about
the inference any more than about the fact. Yet the two
things are totally distinct ; and while I also admit the fact
observed, I totally reject the inference (assumed to be also
a fact) as being absolutely without any direct evidence sup-
porting it. I do not think any English observer has stated
that the young of our summer migrants all gather together
in autumn and leave the country before the old birds ; the
American observers state that their migrating birds do not
do so; while many facts observed at Heligoland show that
no such inference is required to explain the admitted fact.
Let us see what these additional facts are.
The enormous rushes of mic^ratorv birds which rest at
Heligoland always occur at night, and are very intermittent.
162
THE WORLD OF LIFE
They usuallj take place on dark nights, sometimes in mil-
lions; at other times, a week will sometimes pass with only
a few stragglers. Of one such pitch-dark night Mr. Seebohm
writes :
Fig. 22.— The Light-
house at Heligoland on a
Migration Night.
" Arrived at the lighthouse, an intensely interesting scene pre-
sented itself. The whole of the zone of light within range of the
mirrors was alive with the birds coming and going. Nothing else
was visible in the darkness of the night, but the lanthorn of the
lighthouse vignetted in a drifting sea of birds. From the darkness
in the east, clouds of birds were continually emerging in an unin-
terrupted stream ; a few swerved from their course, fluttered for a
moment as if dazzled by the light, and then gradually vanished
with the rest in the western gloom. ... I should be afraid to
hazard a guess as to the hundreds of thousands that must have
passed in a couple of hours ; but the stray birds that the lighthouse-
man succeeded in capturing amounted to nearly 300."
He also tells us that 15,000 sky-larks have been caught
on Helifi^oland in one nio-ht ; and all aiiTee that the count-
CASES OF ADAPTATIOjST 163
less myriads that are seen passing over Heligoland are but
a minute fraction of those that really pass, high up and quite
out of sight. This is shown by the fact, that if, on a dark
night, it suddenly clears and the moon comes out, the swarms
of birds immediately cease. Another fact is, that, on what
the islanders call '' good nights,'^ the birds that come to rest
seem to drop down suddenly out of the sky. One other fact
is mentioned by Mr. Seebohm. It is that every year the reg-
ular migration season is preceded by a week or two, during
which a few stragglers appear ; and these are all old birds
and many of them slightly crippled, or partially moulted, or
without some of their toes, or onlv half a tail, or some other
defect. These are supposed to be mostly unmated birds or
those whose young have been destroyed. It is also supposed
that, during favourable weather (for the birds) migration goes
on continuously during the season of about six weeks, though
for the most part invisible at Heligoland, but often audible
when quite invisible.
Xow, the fact of the young birds only appearing on Heligo-
land for the first week or so of the season of each species is
easily explicable. Rem.embering that the autumnal migration
includes most of the parent birds and such of their broods as
have sur^dved, it is probable that the latter will form at least
half or, more often, two-thirds of each migrating flock. But
the young birds, not having yet acquired the full strength
of the adults, and having had little, if any experience, in
long and continuous flights, a considerable proportion of them
on the occasion of their first long flight over the sea, on see-
ing the lighthouse and knowing already that lights imply land
and food-crops below them, and being also much fatigued, will
simply drop down to rest just as they are described as do-
ing. The old birds and the stronger young ones, however,
pass high over head, till they reach the north coast of Hol-
land, or, in some cases, pass over to our eastern coasts. We
must also remember that the loncrer the birds are in mak-
ing the journey overland, the more young birds are lost by
164 THE WORLD OF LIFE
the attacks of birds-of-prey and other enemies. Hence the
earliest flocks will have a larger proportion of young birds than
the later ones. The earlier flocks also, being less pressed for
time will be able to choose fine weather for the crossing, and
thus it will be only the young and quickly-fatigued birds that
will probably fly low and come dow^n to rest. Later on every
recurrence of bad weather will drive down old and young alike
for temporary shelter and rest. Thus all the facts are ex-
plained without having recourse to the wildly improbable
hypothesis of flocks of immature birds migrating over land
and sea quite alone, and a week in advance of their parents
or guides.
What this World-wide Adaptation teaches us
This co-adaptation of two of the highest and most marvel-
lous developments of the vast world of life — birds and in-
sects — an adaptation which in various forms pervades all
their manifestations upon the earth, from the snow^-wastes of
the tundra to the glorious equatorial forests; and the further
co-adaptation of both, with the vegetation amid w'hich they
have developed, suggest some very important considerations.
As we might expect, both birds and insects are comparatively
rare in a fossil state, but there are suflicient indications that
the latter were first developed. A considerable number have
been found in the Coal Measures, especially numerous cock-
roaches. Ancestral forms of ^N^europtera and Hemiptera allied
to our may-flies and dragon-flies, bugs and aphides, are found
in Devonian and Carboniferous rocks. The more his^hlv
organised insects with a complete metamorphosis, come later;
beetles, dragon-flies, and bugs (Hemiptera) are rather common
in Lias beds, and here, for the first time, we meet with a
true ancestral bird with perfectly developed wings and
feathers, and with toothed jaw^s, the celebrated Archseopteryx.
Diptera (flies) are also found here, as ^vell as a wasp, some-
what doubtfully identified ; while the most highly developed
of all insects in structure and metamorphosis, as well as in
CASES OF ADAPTATION" 16^
o
size and beauty, the Lepidoptera, are first in Tertiary beds,
at a time when birds allied to living forms also first appeared.
This general parallelism of development seems clearly to
indicate that birds, in the full and varied perfection in which
we now find them, are dependent on a correspondingly wide-
spread development of insects ; and more especially of those
higher orders of insects, whose exceedingly diverse stages of
larva, pupa, and perfect insect, afforded the special food for
immature and full-grown birds respectively. We can see how
the omnipresence of insects adapted to feed on every kind of
vegetable food, as well as on all kinds of animal refuse, has
afforded sustenance to the various kinds of small mammalia,
reptiles, and birds, which have successively become specialised
to capture and feed on them. The early birds with toothed
jaws were able to feed upon the cockroaches and ancestral
iVTeuroptera and beetles of the same period. As these early,
birds became more numerous, so they became successively
specialised to feed upon particular kinds of insects or their
larvae, however completely these might seem to be concealed
or protected. Thus were gradually formed the true fly-
catchers (Muscicapidge) and the totally distinct American fly-
catchers or tyrant birds (Tyrannidse), which capture all kinds
of insects on the wing; the swallows, and the very distinct
swifts, so specialised as almost to live in the air, and to feed
on this kind of food exclusively; the goatsuckers, which
capture night-flying insects; the curious little nuthatches and
creepers which hunt over trees for small beetles concealed in
crevices of the bark; while the marvellously specialised wood-
peckers discover the larger grubs or caterpillars which burrow
deeply into the wood of trees, and dig down to them with
their wonderfully constructed hammer-and-chisel-like head
and bill, and then pull them out on the tip of their extensile
barbed tongue. In the tropics many distinct families of birds
have been developed to grapple with the larger and more
varied insect forms of those countries, so that it mav be
safely concluded that no group of the vast assemblage of in-
166 THE WORLD OF LIFE
sects but what has its more or less dangerous enemies among
the birds. Even the great rapacious birds, the hawks, buz-
zards, and owls, when their special food, the smaller mammals
and birds, fails them, will capture almost every kind of
ground-feeding insects; while the enormous tribes which feed
largely on frnits and seeds often make up for its deficiency
by capturing such insects as are available.
One of the clearest deductions from these facts is, that the
great variety of the smaller birds — warblers, stonechats, tits,
w^agtails, pipits, wrens, and larks — owes its origin to the
continuous specialisation throughout the ages of new forms of
birds adapted to take advantage of every fresh development
of the insect tribes as they successively came into existence.
As Darwin repeatedly impresses upon us, excessive powers of
multiplication with ever-present variations, lead to the almost
instant occupation of every vacant place in the economy of
nature, by some creature best fitted to take advantage of it.
Every slight difference in the shape or size of bill, feet, toes,
wing, or tail, or of colour of the various parts, or of supe-
rior acuteness in anv of the senses, such as we can see in the
different allied species of these birds, has been sufficient to
secure the possession of some one of these vacant places ; and
when this first partial adaptation has been rendered more and
more perfect by the survival in each successive generation of
those individuals best fitted for the exact conditions of the
new environment, a position is reached which becomes at any
future time a secure starting-point for further modification,
either in the same or in any slightly diverging line, so as to
be again fitted to occupy some other vacant place which may
have arisen through the slightest changes either in the inor-
ganic or the organic environment.
So long as we limit ourselves to a consideration of the mode
in which any existing species has been produced, by the
adaptive modification of some other pre-existing closely allied
species, by means of the known facts of universal variation
and of the constant survival of the best adapted, there is no
CASES OF ADAPTATION 167
difficulty whatever in accepting the " origin of species " from
other species as a demonstrated fact ; and this alone was the
hitherto insoluble problem Avhich Darwin first succeeded in
solving. It is only in the extension of the process to isolated
groups such as the whales, the elephants, the serpents, or the
mammalia; or by enquiring how special organs, such as horns,
teeth, ears, or eyes, could have begun their process of develop-
ment, that difficulties appear, many of which seem, to some
biologists, to be insuperable. But many of these difficult
problems have been solved by more complete knowledge ; while
others have been rendered easy by the discovery of inter-
mediate stages either through the investigations of embryolo-
gists, or of palaeontologists, so that many of the greatest diffi-
culties of Darwin's early opponents have quite disappeared.
Some of these recent explanations have been referred to al-
ready, and many others are briefly described in my Darwin-
ism. In that work also I have given so many illustrations
of the way in which natural selection has worked, that it will
be needless for me to go into further details here. I will,
therefore, now proceed to an exposition of some problems of
a more general nature, which involve difficulties and sugges-
tions beyond the scope of Dar^vin's work, and which, I think,
have not been sufficiently considered by later writers on evolu-
tion.
CHAPTER IX
THE IMPORTANCE OF EECOGNITION-MAKKS FOR EVOLUTION
The great problem of the exact causes of the infinitely varied
colours and markings of the different species of the higher
animals, is now gradually receiving an adequate amount of
attention, and in consequence an almost complete solution.
In the Origin of Species Darwin dealt with only one branch,
of the subject — coloration for concealment, and that only in-
cidentally ; but he at once accepted, and with enthusiasm,
Bates's explanation of the beautiful phenomena of mimicry
among insects, and also that of warning colours in the in-
edible caterpillars, first suggested by myself.
The whole subject, especially that of mimicry, is now so
largely developed as to require many volumes for its adequate
exposition ; and I have myself given a summary of the more
interesting facts in my Darwinism: I shall therefore deal very
briefly with it here, with the one exception of that form of
it which I have named " recognition marks." These, though
the last to be generally accepted have received the least at-
. tent ion ; but, after many years' consideration of the whole
problem of evolution I have come to the conclusion that, of
all the causes of distinctive marking (among the higher ani-
mals at all events), the need for easy recognition under the
varied conditions of their existence is for most animals the
most important. It is, however, on account of their being
in most cases absolutely essential as a factor in the evolution
of new species that I here devote the larger part of this chapter
to their consideration.
168
KECOGA^ITIO^^ -MARKS 169
Coloration for Concealment and for Visibility
Colour and markings for concealment pervade all nature.
The hare on its form, the snipe in its covert, the vast major-
ity of birds while sitting on their nests, the sand-coloured des-
ert animals, and the prevalence of green colours in the in-
habitants of tropical forests, are a few of the best-known ex-
amples. The uses of such colours in order to protect the
Herbivora from enemies, or to conceal those which devour
other animals from their prey was at once acknowledged, and
it was seen how, with variability of colour as a constant fact,
survival of the fittest might soon bring about the beautiful
harmony of coloration we everywhere find to prevail. But it
was also undeniable that there were almost equal numbers
of animals of all classes and sizes, in which colours and mark-
ings occurred which could not by any possibility be interpreted
as protective, because they seemed to render the creature
glaringly conspicuous. Some of these, which w^ere most prev-
alent among insects, were soon explained as " warning
colours,' ' because they were exhibited by species which were
either so nauseous as to be inedible by most insect-eaters ; or
were armed wdth stings which might cause great pain or even
loss of life to an enemy which attacked them. When it was
found that many other groups of insects which did not pos-
sess these protective qualities, yet acquired the same colours
and often the same form ; and when my fellow-traveller on
the Amazon, II. W. Bates, showed how this peculiar kind of
^^ mimicry " was beautifully explained on the Danvinian
hypothesis, not only w^as the theory itself greatly strengthened
but a whole host of curious and beautiful colour-phenomena
in Xature, hitherto unnoticed, were seen to come under some
form of the same general principle. As one rather extreme ex-
ample of mimicry I give the figures of a black wasp with white-
banded wings, which is closely imitated by a heteromcrous
beetle. These I captured myself in the forests of Borneo, fly-
ing together near the ground. They are of nearly the same
170 THE WOKLD OF LIFE
size. The wing-coverts (elytra) of the beetle are reduced to
pointed scales, allowing the true wings to be always extended.
This is most unusual in beetles, as is the white band across
the wings in this order of insects (Fig. 23). This strange
and most unusual modification of an inoffensive insect, so
as closely to resemble one of another order which is protected
by a dangerous sting, can be explained in no other way than
through the advantage derived by the harmless beetle by be-
ing mistaken for the wasp. Of course, this change is the
result of a very long series of slight modifications of the beetle,
each bringing it a little nearer to the wasp, a series extend-
ing probably through thousands or even millions of genera-
tions.^
Becogniiion-Marlcs
But though the subject of '^ mimicry " involves problems
of extreme complexity and interest, and has therefore at-
tracted the attention of numerous students, yet it is almost
entirely confined to the insect world, and, taken as a whole,
is not nearly so important a factor in the development of the
great Avorld of life as the class of " recognition "-colours of
which I will now give a short account.
My attention was first directed to this subject during my
visit to south Celebes in 1856-57, where, during about six
months' collecting, I obtained the unusual number of fifteen
different birds of prey, of which the majority were of the
hawk sub-family. While skinning and preserving these birds,
and after my return home, wdiile determining the species, I
could not help observing in many of them the varied and
1 Other cases are given in my Darwinism ; but those who wish to under-
stand the whole problem and what an important part it plays in nature
should read Professor Poulton's elaborate papers in the Transactions of
the Entomological Society of London for the years 1902 and 1908, together
with those of Dr. F. A. Dixey and other writers. There is also a very good
article by Mr. E,. Shelford, on mimetic insects from Borneo, and as these
are illusttated by coloured plates and deal with cases of the same nature as
the one here given, they are very instructive. (See Proceedings of the
Zoological Society of London, Nov. 4, 1902.)
beetle.
i.MYCNIMIA AVICULUS.
2.C0L0B0RH0MBUS FASCIATIPENNIS,
Fig. 23. — Mimicry of Wasp by a Beetle.
EECOGNITION-MAEKS 171
beautiful markings of the tail-feathers, by means of white
spots or bands on all the feathers except the middle pair.
The result was that when the tail was expanded during
flight, it was seen to be marked very conspicuously by white
bands, sometimes across the middle of the tail, sometimes at
the end, sometimes with one band, sometimes with two or even
three, so that the species were easily distinguished by this one
character. But the chief peculiarity to be noticed was, that
these bands w^ere only seen during flight, the white markings
being quite invisible when the birds were at rest. The impor-
tance of this fact I did not see till many years later, when,
in connection with other similar facts, it gave a clue to their
meaning and purpose.
Xow that we have learnt how rapid are the powers of in-
crease of all animals, and the extreme severity of the process
by which the population is kept down to a nearly fixed amount
by the annual destruction of all the less adapted ; and further,
when we know how all the higher animals roam about in
search of their daily food, we are able to understand how
vitally important it is for all such animals to be able to recog-
nise their own species from all others without fail and at con-
siderable distances. This is essential for several reasons.
The young and half-grown, if they have strayed away from
the flock or herd, need to rejoin them as soon as possible ; the
two sexes of the same species require to know each other in
the same way by unfailing marks whether they are approach-
ing from behind or from the front; while the separate por-
tions of flocks divided by the sudden attack of some enemy
need to come together again as soon as possible. But there is
a still more important use of these distinctive markings, since
they are almost if not quite essential to the production of neiv
species by adaptation to change of conditions, as will be shown
later on.
I first gave a somewhat full account of this class of mark-
ings, with several characteristic illustrations, in my Darwin-
ism, in 1889; but I had briefly treated the subject in my
172r THE WOELD OF LIFE
lecture on the Colours of Animals given at many places in
the United States and Canada in 1886-87, and in England in
1888. No doubt some of the facts had been noted by other
writers, but I thinlv I was the first to claim for it a high place
among the factors concerned in animal evolution. The clear-
est and most picturesque illustration of the subject 1 have seen
is in a very short article by Mr. E. Seton Thompson in the
American periodical " The Auk " for October 1897, from
which I will quote the most important passage :
" The common jack-rabbit ^ when squatting under a sage-bush
is simply a sage-gray lump without distinctive colour or form. Its
colour in particular is wholly protective, and it is usually accident
rather than sharpness of vision which betrays the creature as it
squats. But the moment it springs it is wholly changed. It is
diflScult to realise that this is the same animal. It bounds away
with erect ears showing the black and white markings on their back
and underside. The black nape is exposed. The tail is carried
straight down, exposing its black upper part surrounded by a region
of snowy white ; its legs and belly show clear white, and everything
that sees it is clearly notified that this is a jach-rabhit. The coyote,
the fox, the wolf, the badger, etc., realise that it is useless to follow ;
the cotton-tail, the jumping rat, the fawn, the prairie dog, etc., that
it is needless to flee; the young jack-rabbit that this is its near
relative, and the next jack-rabbit that this may be its mate. And
thus, though incidentally useful to other species at times, the sum
total of all this clear labelling is vastly serviceable to the jack-rab-
bit, and saves it much pains to escape from real or imaginary
dangers. As soon as it squats again all the directive marks disap-
pear, and the protective gray alone is seen. In the bird-world the
same general rule applies. When sitting, birds are protectively
coloured; when flying, directivelyf i
The African antelopes offer very striking examples of
" recognition "-marks, especially those that inhabit Central and
South Africa, where such indications are most needed. The
land is generally open, often quite bare, but usually with scat-
1 This appears to be the common grey hare {Lepiis a^nericanus) .
KECOGNITION-MAEKS 173
tered trees and bushes ; and as these animals roam over a
great extent of country in search of food or water, and are
also liable to the attacks of many dangerous beasts of prey,
their safety depends largely on their keeping together in small
or large herds. There are nearly a hundred different kinds
of antelopes known to inhabit Africa, the larger part of them
being found in Central and South Africa. Almost all of these
have very distinctive markings on a general ground-colour
harmonising with the tint of the soil or rock. These mark-
ings are usually confined to white patches on the head and
face, and on the hinder parts, so as to be visible in the two
directions that are most serviceable.-^ I have also come to
the conclusion that the horns of these animals, though pri-
marily developed as weapons of defence — for even the lion
is occasionally killed by the horns of the gemsbuck — have
been so changed in each species as to serve another purpose,
as is so often the case in nature. Their curious modifica-
tions of form in closely allied species, and their extreme
diversity in the whole group, leads me to conclude that their
actual shapes have been produced quite as much for purposes
of recognition as for attack or defence. While moving among
high grass or bushes, or when at rest and '^ ruminating," the
horns would often be the only part visible at a distance ; and
this, in a district inhabited by perhaps a dozen different species
of these animals, would be of the greatest importance in guid-
ing a wanderer back to his own herd, and for other purposes.
To illustrate this I here give views of the horns or heads of
twelve different species of antelopes all found in Central or
South Africa, and thus often meeting in the same valley or
veldt. To these I call the reader's special attention (Figs. 24-
35).
The first group of four shows two of the larger antelopes
1 The beautiful gazelle figured in my Darwinism (p. 219) shows both
these kinds of markings very strongly; while an examination of the numer-
ous figures of antelopes in Wood's Natural History (or in any of the more
recent illustrated works) aff'ords numerous examples of them.
174 THE WORLD OF LIFE
on the left, which, with a general likeness of form, possess
individuality both in face-marks and in the curvature of the
horns ; while the two gazelles on the right are still more
distinct. The next group consists of three species of the
genus Cobus, in w^hich the horns are each so distinct in size
and curvature as to be easily recognisable at considerable dis-
tances ; the fourth figure shows the horns of the gemsbuck, a
very distinct species, not only in the body markings, but also
in the almost perfectly straight and very long horns. The
third group shows, at the top, the two species of kudu, the
horns of which, though exactly alike in spiral curvature, are
yet placed at such a different angle on the head as to be easily
distinguishable. The two lower figures are of animals not
closely allied, but, as one inhabits East and the other South
Africa, their ranges probably overlap each other, or once did
so. Here there is a somewhat similar bend in the horns, but
their thickness and direction render them absolutely distinct
from every point of view.
^Now, as the antelopes are very closely allied to each other,
both in structure and external form, it seems improbable that
all the diversities in the horns (which are sometimes very
great in closely allied species) should have been acquired for
the sole purpose of fighting with each other or with an enemy.
But as these animals all possess markings on the head and
body which can only be interpreted as recognition-marks es-
pecially serviceable while in motion, it seems quite natural that
the horns should have been modified to serve the same pur-
pose while the animals are at rest, or when their bodies are
wholly and their faces partially concealed by the grasses or
bushes around them.
The essential character of directive or recognition-marks
is strikingly shown by one of the best known of the African
antelopes — the springbok — which in the early days of the
Cape Colony swarmed over the whole of South Africa, even
in the vicinity of Cape Town. Its chief feature is thus de-
scribed in Chambers's Encyclopaedia :
Fig. 24.
TrageJayhus spekei.
Fig. 25.
Boocercus euryceros.
Fig. 26. Fig. 27.
Gazella granti. Gazella ualleri.
Recognition-Marks in African Antelopes.
KECOGNITION-MAEKS 175
" Two curious folds of skin ascend from the root of the tail to
near the middle of the back; they are closed when the animal is
at rest, but when leaping or running they open out and disclose a
large white patch, which is otherwise concealed."
We have here a structural peculiarity leading to the pro-
duction of a distinctive white patch on a prominent part of
the body, which patch is concealed Avhen not required and
when it might be dangerous, and only exhibited in the pres-
ence of some real or imaginary danger, for the sj^ringbok is
said to be one of the most timid and cautious of all animals.
This curious feature is more remarkable, and more clearly a
proof of a mark designed to he seen, than even our rabbit's
upturned tail wdien running, wdiich has been termed the
*^ signal Hag of danger," and in moonlight or evening twilight
serves, on the approach of an enemy, to guide the young, or
those farthest from home, towards the family burrow.
Recognition-Marks in Birds
A large number of birds also possess these two kinds of
recognition-markings, the one to be seen when resting or feed-
ing, the other only during flight. As good examples of these
I give figures of the head and wings of three allied species
of stone-curlews, inhabiting Eastern Australia, the Malay
Archipelago, and India, respectively, whose ranges sometimes
overlap, and which are no doubt descended from a common
ancestor. The head of each exhibits different markiuirs, bv
which they can be easily distingTiished while feeding on the
ground ; while the bolder markings on the wings enable them
to keep together during their wanderings or migrations (Figs.
36, 37, and 38).
Markings of this character, though varied almost infinitely,
occur in all classes of the hioher animals, and very mucli
in proportion as their mode of life requires them. When con-
cealment is of more importance, then the recognition is made
effective by differences of shape or of motions and attitudes,
176
THE WORLD OF LIFE
or hy special cries, as in the cuckoo. Among the birds of
the tropical forests, while the ground colour is often protec-
tive, as in the green of parrots, the smaller fruit-pigeons of
Fig. 36. — (Edicnemus grallarius (East Australian Stone-Curlew).
This species is found all over Eastern Australia and the coasts of the Gulf of
Carpentaria. It is distinguished from its allies by the better defined whit©
spot on the wing and its more conspicuous markings on the breast.
Fig. 37. — (Edicnemus magnirostris (Austro-Malayan Stone-Curlew).
This species ranges from the Andaman Islands to the Philippines and the north
coast of Australia. The markings of the face are almost intermediate be-
tween those of the other two species.
the Malay Archipelago, many of the barbets, and hosts of other
birds, yet the different species will be almost always charac-
Fig. 28.
Strepsiceros kudu.
FIG. 29.
Strejisiceros im herb is.
FIG. 30.
Buhalis jacksoni.
Fig. 31.
JEpyceros melampus.
Recognition-Marks in African Antelopes.
RECOG^^ITION-MARKS
>-^7
177
terised bj spots or bands, or caps of brilliant or contrasted
colours. But as these usually break up the green body into
irregular portions, and as flowers of equally varied hues are
common on trees, or on the orchids and other epiphytes that
Fig. 38. — (Edicnemus recurvirostris (Great Indian Stone-Curlew).
This species is found all over India, and also in Ceylon and Burma. This species
is clearly defined by the upturned bill and the compact black mark around the
eye.
grow upon their branches, the general effect is by no means con-
spicuous.
]^ow, without this principle of the necessity for external
differences for purposes of recognition of each species by their
own kind, and especially of the sexes by each other, this end-
less diversity of colour and marking, when not protective, seems
difficult to explain. The Duke of Argyll, in his interesting
work, The Reign of Law, published six years after the Origin
of Species, expressed this objection very forcibly. After de-
scribing many of the wonderful forms and ornaments of the
humming-birds, he says :
" Mere ornament and variety of form, and these for their own
sake, is the only principle or rule with reference to which Creative
Power seems to have worked in these wonderful and beautiful
birds. ... A crest of topaz is no better in the struggle for
existence than a crest of sapphire. A frill ending in spangles of
178 THE WORLD OF LIFE
the emerald is no better in the battle of life than a frill ending
in spangles of the ruby. A tail is not affected for the purpose of
flight, whether its marginal or its central feathers are decorated
with white. . . . Mere beauty and mere variety, for their own
sake, are objects w^hich we ourselves seek when we can make the
forces of nature subordinate to the attainment of them. There
seems to be no conceivable reason why we should doubt or question
that these are ends and aims also in the forms given to living or-
ganisms."
In a criticism of the Duke's book (written in 1867) I
adduced sexual preference by the female bird as sufficiently
explaining these varieties of plumage and colour, but I have
since come to doubt the validity of this, except so far as the
plumes are an indication of sexual maturity; while I see in
the need for outward marking, whether for purposes of recog-
nition or as preventing intercrossing between incipient species,
a sufficient cause for all such conspicuous indications of
specific diversity as are found perv^ading the whole vast world
of life. It now only remains to point out how these mark-
ings have been produced, even under conditions which some
writers have considered must render their production for this
purpose impossible, and therefore as constituting a valid ob-
jection to the whole theory of recognition-marks.
An Objection to Recognition-Marhs answered
In a book on Darwinism and Lamarckism, the late Captain
Hutton, a well-known Kew Zealand naturalist, objected to the
validity of recognition-marks as a cause for the development
of specific characters, that there are, all over the Pacific,
numerous cases of small fruit-pigeons of the genus Ptilopus,
which each have distinctive markings, and are almost always
confined to one island or a small group of islands. In most
of these cases there is no other pigeon or other bird on the
same island for which they could possibly be mistaken. He
then says :
^
fr
^
Fto. 32.
Cohiis leche.
Fig. 33.
Col) us defdssd.
FIG. 34.
Cohus maria
Fig. 35.
Oryx (lazclUi.
RECOG.MTIO.N M \HKS IX Afuua.n AXTKI.orKS.
EECOGXITIOX-MAEKS 179
^^ Consequently it appears certain that most of these species were
developed singly, each in its own island. If this he the case,
the colours which now distinguish tlic dilferent species cannot be
recognition-marks, because there is no other species in each island
with which they could be confounded."
Shortly afterwards the late Dr. St. George Mivart made
the same objection as regards the very numerous species of
beautifully coloured, lories Avhich are found in all the islands
around Xew Guinea and in the Western Pacific. He urijed
that the various peculiarities of colour cannot be useful as
recognition-marks, because the colour and markings of each
of the 2,'enera of these birds is so very distinct from that of
all other birds inhabiting the same island, and there is usually
only one species in each island. This argument, looked at
superficially, seems very strong, but it is not difficult to show^
that it is a complete fallacy, if we follow out in detail what
must have occurred in each case.
It is clear, admitting evolution (as both these writers did
admit it), that each of the species of pigeon or lory noW'
peculiar to an island must have originated from some parent
species in the same or some other island; and there are only
tw^o possible suppositions — either the species originated in is-
land A by modification of the present form, and then migrated
to island B, afterwards becoming extinct in A ; or it migrated
from A to B and became modified into its present form in
B. The latter case is by far the more probable, and as it is
clearly that which the critics contemplated, let us see exactly
what must have happened.
We know as a fact that, when any species reaches an is-
land or other new habitat for the first time, if the conditions
are favourable, it increases with marvellous rapidity, till the
island is fully stocked, and the supply of food at some time
of the year begins to fail, or till some enemy — a rapacious
bird, for instance — finds out the rich banquet, and is soon
followed by others. The rabbit in Xew Zealand and Porto
Santo, the sparrow in the United States, and many others,
180 THE WORLD OF LIFE
are examples of such rapid increase. But as soon as the is-
land is fully stocked, a number equal, or nearly so, to the
annual increase must die off every year, and these will inevi-
tably be the least fitted to survive. Hence natural selection
at once begins to act, and as the conditions, even in two
adjacent islands, are never quite the same, and as with such
a large population slight variations in many directions will
be very numerous, some modification to a more perfectly
adapted form will necessarily follow. Here comes the point
which both critics failed to notice, that the modification of
the species into a better-adapted one must have occurred in
the island ; and as it is universally admitted that intercrossing
between the incipient species and the parent stock would be a
serious check to adaptation ; and further, that varieties of the
higher animals prefer to mate with their like, then any varia-
tion of colour in those better adapted will be advantageous,
will lead to more rapid change, and will thus come to charac-
terise the new form as distinguished from that of the less-
adapted parental form.
It is clear, therefore, that species which are now peculiar
to some island or other restricted locality, even when thev
are quite unlike anything else now living around them, must
have become differentiated from some parent stock just in the
same way as all other species have become differentiated.
During all the initial stages, w^hich may have occupied scores
or hundreds of generations, some outward sign of the struc-
tural change that was taking place was an essential part of
the process, as a means of checking interbreeding with the less-
modified parental form, which might linger on till the process
was almost completed. Now, the distinctive recognition-mark
seems to us to have no use ; but as the original form from the
adjacent island A may still occasionally visit or be driven to
the island B, it would now be treated as a stranger, and thus
prevent the better-adapted form being deteriorated by inter-
breeding with the less-adapted immigTant.
EECOGXITIOX-MAEKS 181
Recognition hy Butterflies
This case shows how easy it is to make mistakes or arrive
at wrong conchisions, imless we take account of all the de-
tails of a problem, and endeavour to follow out the exact proc-
esses of nature by the help of facts known to us. I can
say this with more confidence, because I find that I have
myself come to a hasty conclusion, which I now see to be er-
roneous, on one aspect of this very question ; and as it in-
volves a problem of some importance I will here state what it
is. I find that in all my writings on this subject I have as-
sumed, without going into details, that the theory of ^^ recog-
nition-marks," which so well accounts for a very widespread
type of marking and coloration in birds and mammals, is also
applicable to a large portion of the markings of insects, es-
pecially in the case of butterflies. But a little consideration
shows that there is no resemblance between the two cases.
Young mammals and birds grow up with their parents, and
get to know their appearance in every detail. They also
have usually brothers and sisters growing up with them, so
that by the time they go out into the w^orld to care for them-
selves they are thoroughly acquainted with the difference be-
tween themselves and other species, even those nearly allied
to them. This complete knowledge is increased by the fact
that they are able, through the mobility of the head and neck,
to see almost every part of their own bodies, and thus know
that they themselves do resemble their parents.
But with the butterflies, and most other insects, everything
is different. The caterpillar never knows its parent, and when
the butterfly emerges from the pupa and takes flight, it seems
quite impossible that, among the numerous butterflies of all
sizes, shapes, and colours that it may immediately encounter,
it can possibly know, h^j sight, which are of its own race. Tt
must be remembered that from tlie position nf its eyes if
cannot see itself except at so oblique an angle as to be al-
most useless; and when we consider the extreme diversity of
7 t/
182 THE WORLD OE LIEE
the sexes in many butterflies this adds to the difficulty of
supposing vision to be the 'primary means of recognition. But
it may be a secondary means. It is well known that in some
moths the females attract males by scores at night, and this
can only be by scent, or something analogous to it. It is
also known that the males of manv butterflies emit a strong
perfume which has been traced to certain peculiarly formed
scales on the wings. Scales, apparently of a similar nature,
have been found in several distinct families of butterflies and
moths, and it seems probable that the function of these is
in all cases to produce a perfume agreeable to the other sex,
though only in a few cases is such perfume perceptible to
us.
It seems probable, therefore, that the sexes of Lepidoptera
are mutually attracted by a perfume agreeable to each other,
but disagreeable or neutral to others of the same sex or to
other species. Each time this attractive odour was perceived
and the source of it traced, the visual image of the insect
would be connected with the smell, and thus only would the
colour and markings of the species become known and be
distinguished from that of other species. This being the
case, we see that the complete scaly covering of so many of
these insects serves a double purpose. It affords the means
of using an extended surface for the highly important scent-
glands, which, by serving to bring together the sexes of each
species and to prevent intercrossing, would facilitate differ-
entiation and lead to that wonderful diversity of colour and
marking accompanying comparatively slight differences of
structure for which this order is so remarkable, and which are
absolutely unequalled in the whole animal kingdom. This
variety of colour, rendered possible by the large wing-surface
covered with small but exquisitely organised scales, is util-
ised for securing the safety of the perfect insect to a sufficient
extent to provide for the continuance of the race, thus keep-
ing up that endless variety of form and colour which is, per-
haps, one purpose of their existence.
KECOGNITIOX-MAliXS 183
The first great adaptation here, as throughout nature, is
to secure conceahnent from their most dangerous enemies, and
this is effected by various kinds of protective, deceptive, or
-warning coloration which in some form or other pervades the
whole order, and forms a most fascinating subject of study.
The protective coloration is mostly on the under sides of the
wings of butterflies, and on the upper sides of the upper wings
of moths, the parts respectively exposed to view when the in-
sect is at rest. Great numbers are also deceptively coloured
by eye-marks (ocelli), which resemble the eyes of mammals
in such a way as to be very striking in the mingled light and
gloom of the forest and in the general surroundings of each
species. Large groups in all the tropical regions possess warn-
ing colours, either very bright and well contrasted, or of sober
browns and yellows, and accompanied by such elongated wings,
bodies, and antennae, that the facies of the whole group as
well as of the individual species soon become known to in-
sect-eating creatures.
Those which are protectively or deceptively coloui-ed on
the exposed portions of their wings often exhibit the most
brilliant or gaudily contrasted colours elsew^here; but in these
cases the flight is very rapid or jerky, and the insects are so
continually hidden among the lights and shadows of the forest,
that few enemies can capture them. The - great exj)anse of
the wings is itself an additional protection by diverting at-
tention from the body ; and it has thus become possible, with-
out endangering the continuance of the species, to allow the
development of that marvellous display of colour, the charm
of which can only be fully appreciated by those who have for
long periods sought it out in the forest regions of the Amazon,
of the Eastern Himalayas, or of the Moluccas and Xew
Guinea — the three most productive regions in the world for
butterflies (ajiS also for birds) of resplendent hues and in
endless variety.
184 THE WOKLD OF LIFE
A new Alignment against Female Choice
Here again we find another, and I think a very conclusive
argument against female choice having had any part in the
production of beautiful and varied colours in the males of
butterflies, or probably of any insects, since it is clear that
the attraction is through another sense than that of sight, and
all that vision can do in this direction is to enable the in-
\ sect to recognise, perhaps at a greater distance, the individuals
which are thus attractive. There is much evidence to support
this view. H. Miiller, in his Fertilisation of Flowers, states
that odour is pre-eminent in attracting insects to flowers, and,
next to that, general conspicuousness rather than any special
colour or form. And, by his detailed accounts of insects
visiting flowers, we find that almost all the commoner butter-
flies visit a great variety of honey-bearing flowers W'ithout
much regard to colour. Thus Argynnis papliia visited flowers
of four different natural orders, whose flowers w^ere white or
pale red ; the large cabbage butterflies visited seven different
orders, including red, white, purple, yellow, or blue flowers;
the small tortoise-shell visited an even greater range of flowers
and colours, so that we have no reason to impute to these in-
sects anything more than the power to recognise, after experi-
ence, any conspicuous flowers that produce pleasant odours
and, usually, accessible honey.
A consideration of the whole evidence as to the purpose
served by the excessively varied and brilliant coloration of but-
tei^ies leads us to the conclusion that its presence is due to
general laws of colour-development — some of which will be
discussed in later chapters — whose action is only checked
when such development becomes injurious. In the case of
butterflies, the comparatively short period that elapses between
the emergence of the female from the chrysalis and the dep-
osition of her eggs, and the still shorter period needed for the
special functions of the more brilliantly coloured male to-
gether wdth his power of irregular but rapid flight, render it
EECOGNITIOX-MAEKS 185
possible for the colour-development to attain a degree of
variety and beauty beyond that of all other living things.
The larvae of Lepidoptera in their countless myriads un-
doubtedly constitute an important factor in supporting the
gloriously varied bird-life of the tropics, as we have seen
that they so largely support that of our temperate ^nes.
It is the comparatively small surplus that escapes which is
yet ample for the development of the perfect insects in such
abundance as to keep up an approximately equal supply of
larva? for the next generation of birds. When this is done they
themselves become the prey of birds, lizards, and other insect-
eating animals.
Some General Conclusions from Recognition-Marks
We have thus been led by the study of colour as a means
of recognition by birds and mammals to some very important
general conclusions. The first is, that in both these groups,
it has primarili/ a still more important function, that of facili-
tating the formation of new species during the early stages
of adaptation to changed conditions of life. Its secondary,
but still very important use in many groups, is for easy identi-
fication as alreadv described. That this is the true state of
the case is rendered almost certain by the occurrence of a
large number of species in which the markings for recognition
are noiv unnecessary though they were of the highest impor-
tance during the initial stages of evolution.
Another and still more curious result of the study of this
subject is the evidence it affords that the most varied in colour
and markings ' of all insects — the butterflies — do not, pri-
marily, recognise each other by sight, but by some sense
analogous to that of smell. This seems now to be almost cer-
tain, and it affords the explanation of what would otherwise
be a great difficulty, how the males of polymorphic females, as
in Papilio pammon in the East and Papilio apneas in the West,
numerous American Pieridir and many other groups, in which
the females are coloured as if with the purpose of being as un-
186
THE WOKLD OF LIFE
like their mates as possible, are able to recognise each other.
Intuitive knowledge or " instinct " is now given up by every
thinker; but the proof now given that the only knoiun method
of mutual recognition by Lepidoptera is by scent, explains the
whole difficulty. The colours and markings of these insects
have been produced in adaptive relation to their enemies al-
most exclusively, and this explains the fact that the strangely
diverse females above referred to are, probably in every case,
either protectively coloured or mimics of distasteful forms
in their own district. The fact that several of the Eastern
Papilios have fully tailed females while they themselves are
round-winged, is another indication that sight can have no
part in leading to mutual recognition between the sexes.
The almost universal presence of some form of recognition-
marks in birds and mammals, no less than the proof now af-
forded (and for the first time stated) of their entire absence in
the Lepidoptera, affords, I think, ample justification for the
importance I claim for them, and for the space I have devoted
to them in the present volume.
CHAPTER X
THE EAETIl's SURFACE-CHANGES AS THE CONDITION AND
MOTIVE-POWER OE ORGANIC EVOLUTION
Having now sketched in outline the main factors on which
organic evolution depends — heredity, variation, and rapid
powers of increase — and having shown by a sufficient nuni-
ber of examples that these factors are omnipresent features of
organic life, only varying somewhat in the proportions of their
occurrence in different species, we are now prepared to indi-
cate the conditions under which they have acted in the produc-
tion of those numerous changes of form and structure which we
observe in the various forms of life.
We have seen (in Chapter VI.) that so long as no consid-
erable changes occur in the inorganic world, the effect pro-
duced by the constant interaction between species and species,
or between plants and animals, results in changes of local dis-
tribution of the various species rather than in any important
modification of the species themselves. And there really
seems no reason why such changes should occur ; because when
once complete or sufficiently complete adaptation to conditions
is brought about, the whole of the organic world will bo in a
state of stable equilibrium, with sufficient elasticity in all its
parts to become adjusted to all minor periodical changes of
climate, etc., by temporary changes in numbers, and by the
local distribution of the sliffhtlv altered numbers. Once such
an efpiilibrium is attained, there seems no reason why it should
not be permanent. Xatural selection would keep up the suffi-
cient adaptation of each species, but would not tend to change
them.
Geology proves that the inorganic environment — the
187
188 THE WORLD OF LIFE
earth's surface — is not stable ; but that very considerable
changes in climate, in the contour of the land surface, and
even in the minor distribution of land and water, have con-
tinually occurred during past ages; and that just in proportion
to the evidence for such changes do we find that changes have
occurred in the forms of life inhabiting every part of the
earth. A short statement of the nature of these two groups of
coincident and interdependent changes will therefore be useful
here.
The most general and most arresting facts of world-history,
revealed by geology, are, that the superficial crust of the earth
consists of various " rocks " (including in this term every kind
of inorganic matter of which the crust is composed) deposited
in more or less regular " strata " or layers, one above another ;
that these strata are sometimes horizontal, more often inclined
at various angles to the horizon, and even occasionally vertical;
usually continuing at about the same angle or slope for many
miles, but often curved or waved, or even crumpled up and
contorted in remarkable ways. These various strata consist of
many distinct kinds of rock — sandstones, limestones, clayey
or slaty rocks, metamorphic or gneissic rocks ; and all of these
give distinct evidence of having been deposited in water, both
from mechanical texture and the arrangement of their com-
ponent particles, and also by frequently having embedded in
them the remains of various organisms, those that live in seas
or lakes being by far the most abundant and varied. As an
example of this abundance we may mention the Barton Cliffs
on the Hampshire coast east of Christchurch, where, in a dis-
tance of a few miles, over a thousand distinct species of the
fossilised shells of molluscs, radiates, and other marine animals
have been found.
But the most suggestive fact from our present point of view
is, that almost eveiy mountain-range on the earth presents us
examples of such stratified rock-strata, often with abundant
fossils of marine animals, at enormous heights above the sea-
level. Such are found in the Alps at 8000 feet, in the Andes
EARTH CHANGES AND EVOLUTION 189
at 14,000 feet, and in the Himalayas at 16,000 feet elevation.
Innumerable cases of marine fossils at lesser heights are to be
found in every part of the world, and in rocks of very various
geological age. But the causes that have produced these great
changes of level are still obscure. It is certain, however, that
such changes have been exceedingly gradual in their operation,
and have in all probability been of the same general nature as
those going on at the present day — such as the earthquakes
which, at irregular intervals, occur all over the world.
There is one very instructive mode of ascertaining the rate
of certain changes of the earth's surface which was first pointed
out by Mr. Alfred Tylor more than half a century ago,^ and is
generally accepted by geologists as of great value. The sur-
plus water of the land is carried into the sea by rivers, each
of which has a drainage area which contains a certain number
of square miles. By careful measurements, it is possible to
ascertain how much water flows away every year, and also
how much solid matter is suspended in the water, how much is
chemically dissolved in it, and how much is pushed along its
bed at the mouth. The sum of these three quantities gives us
the cubic yards or cubic miles of solid matter denuded from
the surface of each river-basin in a year; and from this amount
we can easily calculate how much the whole surface is lowered
each year, while some corresponding area of the adjacent sea-
bottom, on which it is deposited, must be proportionally raised.
These measurements have been very carefully made for a num-
ber of large and small rivers in various parts of the world, and
the following results have been accepted as fairly accurate by
Sir A. Geikie : —
The Mississippi lowers its basin 1 foot in 6000 years.
Ganges
2358
Hoang-Ho
1464
Rhone
1528
Danube
6848
Po
729
1 See Phil. Mag., April 1853.
190 THE WORLD OF LIFE
We can easily see here that the rapidity of denudation is
proportionate to the height and extent of the mountain-ranges
in which the river has its sources, combined with the amount of
the average rainfall, and the proportion of plains to uplands
in its whole basin. The Ganges has a large proportion of low-
land plain in its area; the Hoang-Ho has less, and therefore
denudes more rapidly. The Danube and the Mississippi both
drain an enormous area of lowlands where denudation is slight,
and the rainfall of both is moderate; they therefore lower
their basins slowly. The Po drains an enormous extent of
snowy Alps in proportion to its whole basin, and in conse-
quence lowers the land perhaps more rapidly than any impor-
tant river on the globe. On the whole, we may take these
rivers as fairly representative. Their mean rate of denuda-
tion is very nearly one foot in three thousand years, and we
may therefore, till more complete observations are made, take
this as a measure of the average rate of denudation of most of
the great continents.
Of course, the rate of lowering will be extremely unequal,
being at a maximum in the mountains and a minimum in
the plains, where it may not only be nothing at all, but if
they are flooded annually they may be raised instead of
lowered. In the loftier mountains with numerous peaks and
precipitous slopes the average lowering may often be ten times,
and sometimes even a hundred times, the mean amount. In
such districts w^e can even see and hear the process continually
going on. Under every precipice there is a more or less ex-
tensive mass of debris — the " screes " of our lake district ;
and every winter, chiefly through the action of rain and frost,
the rocks above are split off, and can be heard or seen to fall.
Even on grassy hills after a few hours' downpour of rain, in-
numerable trickles of muddy water course down in every di-
rection ; while every streamlet or brook — though usually of
water as clear as crystal — becomes a rapid torrent of mud-
laden w^ater. It is by a consideration of these every-day phe-
nomena in operation over every square yard of thousands of
EAETH CHANGES AND EVOLUTIOiV 191
square miles of surface that we are able to understaucj ami
appreciate the tremendous power of rain and rivers, greatly
assisted by frost, in the disintegration of rocks, which lower
the whole surface of the land at such a rate that, if we had
means of accurate comparison with its condition a few thou-
sand years ago, we should see that in many places the whole
contour and appearance of the surface was changed.
When this mode of estimating the rate of subaerial de-
nudation was first applied to well-known regions, geologists
themselves were surprised at the result. Eor 1 foot in three
thousand years is 1000 feet in three million years, a period
which has always been considered very small in the scale of
time indicated by geological changes. When we consider that
the mean height of all Europe (according to a careful esti-
mate by Sir John Murray) is a little under 1000 feet, we find,
to our astonishment, that, at the average rate of denudation,
the whole would be reduced almost to sea-level in the very
short period of three million years, while all the other great
continents would be reduced to the condition of '^ pene-plains ''
(as the American geologists term it) in about six or eight
million years at the utmost. It is quite certain, therefore,
that there must be some counteracting uplifting agency, either
constantly or intermittently at work, to explain the often-re-
peated elevations and depressions of the surface which the
whole structure and mechanical texture of the vast series of
distinct geological formations with their organic remains, prove
to have taken place.
The exact causes of these alternate elevations and depres-
sions, sometimes on a small, sometimes on a gigantic scale,
have not yet been satisfactorily explained either by geologists
or physicists. Two of the suggested causes are undoubtedly
real ones, and must be constantly acting; but it is alleged by
mathematical physicists that they are not adequate to produce
the whole of the observed effects. They are both, however, ex-
ceedingly interesting, and must be briefly outlined here. We
require first, however, to trace out what becomes of the de-
192 THE WORLD OF LIFE
nuded matter that lowers the continental snrfaces at so rapid
a rate, and is poured into the sea at various points around
their coasts ; and this is the more necessary because recent re-
searches on this matter have led to results as surprising as those
of the measurement of the amount of denudation bv rivers.
During the voyage of the Challenger round the world for
the purpose of oceanic exploration, not only was the depth of
the great oceans determined by numerous lines of soundings
across them in various directions, but, by means of ingenious
apparatus, samples of the sea-bottom w^ere brought up from all
depths, and especially along lines at right angles to the shore
at short distances from each other. The exact physical and
chemical nature of all these samples was accurately determined,
and some most curious results were brought to light.
The earlier geologists had assumed, in the absence of direct
evidence to the contrary, that the suspended matter poured
into the sea by rivers was, sooner or later, by means of winds
and waves and ocean currents, distributed over the whole of
the ocean floors, and was gradually filling up or shallowing
the oceans themselves. But the Challenger researches showed
that this idea was almost as remote as possible from the truth.
The actual facts are, that the wdiole of the land debris, with a
few special and very minute exceptions, are being deposited on
the sea-bottom very near the shore, comparatively speaking,
and all but the very finest material quite close to it. Every-
thing in the nature of gravel or sand, of which so much of the
rocky strata consists, is laid down within a very few miles,
only the finer muddy sediments being carried so far as from
20 to 50 miles from land; w^hile the very finest of all, under
the most favourable conditions, rarely extends beyond 150 and
never exceeds 300 miles from land into the deep ocean. Mr.
A. Agassiz also, has found that the extremely fine mud of the
Mississippi River is never carried to a greater distance than
100 miles from its mouth. If we take even so much as 50
miles for the average distance to which the denuded matter is
carried, w^e find the whole area of deposit around South
EAKTH CHANGES AND EVOLUTION 193
America to be 60,000 square miles. But the area of that con-
tinent is about six million square miles, so that deposition goes
on about a hundred times as fast as denudation ; while over
considerable areas where the deposits are of a sand}^ rather than
of a muddy or slaty nature, it may go on a thousand times as
fast. This is a most important fact which does not appear
to have been taken into full consideration by geologists even
to-day.
The correlative fact as to the ocean bed is, that over the
whole of it, when more than the above-named distances from
land, what are called " deep-sea oozes " are found. These
are formed almost entirely by the calcareous or silicious skele-
tons of minute organisms, together with small quantities of
decomposed pumice and of meteoric or volcanic dust. Along
with these in certain areas the remains of larger marine ani-
mals are found, especially the otoliths (or ear bones) of whales
and the teeth of sharks. And the extreme slowness of the
deposit of these oozes is shown by the fact that it is often im-
possible to bring up a dredging from the bottom that does not
contain some of these bones or teeth. It seems as if much
of the ocean bed were strewn with them ! Now, these oozes,
so easily recognised by their component materials and their or-
ganic remains, form no part of the upheaved crust of the earth
on any of our continents. This is, of itself, a conclusive proof
that oceans and continents have never changed places in the
whole course of known geological time; for if they had done
so (as is still maintained by many rather illogical writers) the
epoch of submergence would be indicated by some fragments,
at least, of the consolidated ocean ooze which must once have
covered the whole continental area.^
1 For a full discussion of this question, see my Darwinism, chap, xii.;
Island Life, chaps, vi. and x.; and Studies Scientific and Social, vol. i.
chap. ii. In this last work the whole argument is summarised and the
numerous converging lines of evidence pointed out.
194 THE WORLD OF LIFE
Thickness of the Earth's Crust
We now have to consider a quite different set of phenomena
which have a very important bearing on the causes which have
produced the elevations and depressions which have occurred
over much of the land surface of the globe. It is a universal
fact that as we descend into the crust of the earth (in deep
wells or mines) the temperature rises at a tolerably uniform
rate, which is found to be on the average one degree Fahr. for
eveiy 47% feet. This rate, if continued downwards, would
reach the temperature of melted rock at a depth of about 20
miles. Hot springs in non-volcanic countries furnish an ad-
ditional proof of the high temperature of the interior. Below
the depth above indicated there would probably be some miles
of rock in a plastic state, while irregularities w^ould result
from the nature of the rock, some being more easily melted than
others.
^ow, it has been ascertained that the various rocks of the
crust are of less specific gravity in the solid state than when
they are liquefied, so that the crust may be looked upon as
actually floating upon the liquid interior, very much as the
polar ice-sheets float upon the ocean. A curious confirmation
of this has been given by measurements of the force of gravity,
which show that near all great mountain masses gravity is di-
minished, not only by the amount due to the mass of the moun-
tain itself, but to about double that amount. This is so uni-
versally the case that it has been concluded that the weight of
the mountain mass is supported by a corresponding mass
forced down into the fluid magma, and hence termed the
^^ roots of the mountains " ; just as every lofty iceberg must
have a mass of submerged ice about nine times as great to sup-
port it in the water. This, of course, proves that the crust is
flexible, and that just as any portion of it is upheaved or made
thicker by additions above, a corresponding increase in thick-
ness must occur below to keep it in equilibrimn.
Thus are explained the ver^^ frequent phenomena of hori-
EARTH CHANGES AND EVOLUTION 195
o
zontal strata occurring in similar beds for thousands of feet
thick, while each successive bed must have been formed at or
near the surface. Such are the deposits recently formed in the
deltas of great rivers, in many of which borings have been
made from 350 to 640 feet deep, with indications that each
successive layer was formed near the surface, and that during
the entire process of deposition the whole area must have been
sinking at a very regular rate. This can best be explained
by the weight of the matter deposited causing the slow sub-
sidence. Exactly similar phenomena occur through the whole
series of the geological formations to the most ancient ; in some
cases strata eight miles in thicloiess showing proofs that the
very lowest beds w^ere not deposited in a deep ocean, but in
quite shallow w^ater near shore. ^
Now, as w-e have seen that, over many areas not far from
shore, deposition may occur 100 or even 1000 times as fast
as denudation, and that this same area is continuously lowered
by the weight forcing the crust downwards, we have a real
and efficient cause for continuous subsidence and the forma-
tion of parallel strata of enormous thicknesses. It remains to
account for the subsequent upheaval of these areas, their tilt-
ing up at various angles, and in many cases their being frac-
tured, curved, or contorted often to an enormous extent and
in a most fantastic manner.
Effects of a Cooling and Contracting Earth
It is universally admitted that the earth is a cooling and
therefore a contracting body. The cooling, however, does not
take place by conduction from the heated interior through the
solid crust, the temperature of which at and near the surface
is due wholly to sun-heat, but by the escape of heated matter
to the surface through innumerable hot or warm springs; by a
continuous flow of heated gases from volcanic areas; and fre-
quent outbursts of red-hot ashes or liquid lavas from vol-
1 In chapter iii. of vol. i. of my Studies Scientific and Social I have given
details of these phenomena on the highest geological authority.
196 THE WORLD OF LIFE
canoes. The springs bring up from great depths a quantity
of matter in solution, and the whole of the above-mentioned
agencies result not only in a very considerable loss of heat, but
also in a very great outflow of solid matter, which, in the course
of ages, must leave extensive cavities at various depths, and
thus produce lines or areas of weakness which almost certainly
determine the mode in which contraction will produce its chief
effects.
As the outer crust for a considerable depth has its tem-
perature determined by solar heat, and also because the tem-
perature at which the rocks become liquid is tolerably uni-
form, the loss of heat, causing shrinkage of the globe as a
whole, must occur in the liquid interior; and, as this becomes
reduced in size, however slowly, it tends to shrink away from
the crust. Hence the crust must readjust itself to the in-
terior, and it can only do so by a process of crumpling up,
owing to each successive concentric layer having a less area
than that above it. This shrinkage has been compared with
that of the rind of a drying-up apple. But the earth's crust
having been for ages subject to ever-varying compressions and
upheavals, and being formed of materials which are of un-
equal strength and tenacity, the actual results will be exceed-
ingly unequal, and the inequalities will be most manifested
along or near to certain lines of weakness caused by earlier
shrinkage due to the same cause.
As the crust will be of greater extent than the contracted
liquid core it has finally to rest upon, and as the chief effects
of contraction are limited to certain directions and to com-
paratively small areas, and if the less fractured and more rigid
portions settle down almost undisturbed upon the contracted
interior, then considerable areas along, or parallel to, the lines
of weakness must be crumpled, fractured, and forced upward,
and thus produce great elevations on the surface, though small
in proportion to the whole dimensions of the earth. IN'ow, the
ocean floors are enormous plains, except that they have, here
and there, volcanic islands rising out of them. The water which
EARTH CHANGES A:N'D EVOLUTION 197
covers them preserves uniform temperature, whicli, at the bot-
tom, is not much above the freezing point of sea-water. We may
conclude, therefore, that they are very nearly stable. Pen-
dulum experiments show that the crust below these oceans is
more dense than the subaerial crust, due, probably, to the uni-
form pressure and temperature they have been subject to for
geologic periods. We may assume, therefore, that they do not
become crumpled or distorted by the contraction of the liquid
earth beneath them. The great plains of Eussia, mostly of
Triassic and Jurassic age, consist of nearly horizontal strata,
while the Alps of Central Europe are greatly upheaved and
contorted ; and the same difference between adjacent areas is
found in the United States, and most probably in all the great
continents.
Mathematical physicists have calculated the possible up-
heavals that could be produced by a shrinking crust at prob-
able rates of contraction, and have declared them to be too
small to account for the elevation of the existing land-
masses above the ocean floors, that is, for the whole differences
of height of the land surfaces. But if, as the Rev. O. Eisher
suggests, the oceanic basins were formed at an early stage of
the earth's consolidation, by the separation from it of the moon
in the way described by Sir George Darwun and accepted by
Sir Robert Ball ; and if the whole wrinkling effect of contrac-
tion is concentrated on a few lines or areas of weakness, al-
ways near existing mountains ; and further, if this cause of
elevation be supplemented by the continual subsidence of large
areas along the margins of all the continents by the weight of
new deposits producing a pressure on the liquid interior, which
must result in upward pressures elsewhere, then it seems pos-
sible that a combination of these causes may be sufficient.
Yet another cause of elevation has recently been demon-
strated. After many unsuccessful attempts, the actual ex-
istence of semi-diurnal lunar tides ivithin iJic earth's interior
has been proved; and such tides must, it is said, generate a
vast amount of heat, culminating at tlio bi-monthly periods of
198
THE WORLD OF LIFE
maximum effect. The heat thus produced would be greatest
where the under surface of the crust was most irregular, that
is, under the land surfaces, and especially under the ^' roots of
mountains " projecting below the general level. Their cumu-
lative results would, therefore, add to the upward forces pro-
duced by contraction along lines of weakness.^
But whether the various forces here suggested have been
the only forces in operation or not, the fact of the repeated
slow elevations and depressions of the earth's surface is un-
doubted. The most general phenomenon seems to have been
the very slow elevation of gTcat beds of strata, deposited one
above another along the coasts of a continental mass, or some-
times along the shores of inland seas; immediately followed
by a process of denudation of this surface by rain and rivers,
which, as the elevation continued, carved it out into a complex
series of valleys and ridges till it ceased to rise farther. The
denudation continuing, the whole mass became worn away into
lowland plains and valleys. Then, after a long period of
quiescence, subsidence began, and as the land sank beneath the
water new deposits were laid down over it. Sometimes re-
peated elevations and depressions of small extent occurred;
while at very long intervals there was great and long-continued
subsidence, and, while deeply buried under newer strata, the
older masses were subjected to intense subterranean heat and
compression, which altered their texture, and often crumpled
and folded them up in the strangest manner conceivable.
Then, perhaps, a long period of elevation brought them up and
up, till they were many thousand feet above sea-level ; and,
when the superficial covering of newer beds had been all re-
moved by denudation, the folded strata were themselves ex-
posed to further denudation, and all the strange peaks and
ravines and rushing cataracts of alpine mountains became re-
vealed to us.
1 This sketch of the internal structure of the earth, as affecting elevation
and depression of its surface, is fully discussed in INIr. 0. Fisher's Physics
of the Earth's Crust, a popular abstract of which is given in my Studies
Scientific and Social, vol. i. chap. iii.
EAKTH CHAKGES AND EVOLUTION I'JO
ThuSj in alternate belts or more extended areas, our con-
tinents have been, step by step, built up throughout the ages,
■with repeated alternations of sea and land, of mountain and
valley, of upland plateaus and vast inland seas or lakes, the
indications of which can be clearly traced throughout the ages.
And, along with these purely terrestrial changes, there have
been cosmic changes due to the varying eccentricity of the
earth's orbit and the precession of the equinoxes, loading to
alternations of hot, short summers with long, cold winters, and
the reverse; culminating at very distant intervals in warm and
equable climates over the whole land surface of the globe ; at
other shorter and rarer periods in more or less severe " ice-
ages," like that in which the whole north temperate zone was
plunged during the Pleistocene period, long after the epoch
when man had first appeared upon the earth. ^
Long Persistence of the Motive Power thus caused
It is in tliis long series of physical modifications of the
earth's surface, accompanied by changes of climate, partly due
to astronomical revolutions, and partly to changes in aerial
and oceanic currents dependent on terrestrial causes, that we
find a great motive power for the work of organic evolution,
the mode of operation of which we now have to consider.
Before doing so, however, I would call attention to the fact
of the very extraordinary complexity and delicacy of the
physical forces that have continued to act almost uniformly,
and with no serious break of continuity, during the whole vast
periods of geological time. These forces have always been
curiously balanced, and have been brought into action alter-
nately in opposite directions, so as to maintain, over a large
portion of the globe, land surfaces of infinitely varied forms,
which, though in a state of continuous flux, yet never reached
a stationary condition. Everywhere the land is being low-
ered by denudation towards the sea-level, and part by part is
1 See my Island Life, chapters vii., viii., and ix., for a full discussion of
the causes and effects of glacial periods.
200 THE WOKLD OE LIFE
always sinking below it, yet ever being renewed by elevatory
forces, whose nature and amount we can only partially deter-
mine. Yet these obscure forces have always acted with so
much regularity and certainty that the long, ever-branching
lines of plant and animal development have never been com-
pletely severed. If, on the other hand, the earth's surface had
ever reached a condition of permanent stability, so that both
degrading and elevating forces had come to a standstill, then
the world of life itself would have reached its final stage, and,
w^anting the motive power of environmental change, would have
remained in a state of long-continued uniformity, of which the
geological record affords us no indication whatever.
Readers of my book on Man's Place in the Universe will
remember how, in chapters xi, to xiv., I described the long
series of mechanical, physical, and chemical adjustments of
the earth as a planet, which were absolutely essential to the
development of life upon its surface. The curious series of
geological changes briefly outlined in the present chapter are
truly supplementary to those traced out in my former work.
The conclusion I drew from those numerous cosmic adapta-
tions was that in no other planet of the solar system were the
conditions such as to render the development of organic life
possible upon them — not its existence merely, which is a
vastly different matter. That conclusion seemed to many of
my readers, including some astronomers, geologists, and
physicists, to be incontestable. The addition of the present
series of adaptations, whose continuance throughout the whole
period of world-life history is necessary as furnishing the mo-
tive power of organic development and adaptation, not only
increases to an enormous extent the probability against the de-
velopment of a similar ^^ world of life," culminating in man, in
any other known or reasonably conjectured planet, but af-
fords, in my opinion, an exceedingly powerful argument for an
overruling Mind, which so ordered the forces at work in the
material universe as to render the almost infinitely improbable
EAKTH CHANGES AND EVOLUTION 20i
sequence of events to which I have called attention an actual
reality.
Terrestrial Temperature Adjustments
Among the many wonderful adjustments in the human
body, and in that of all the higher vertebrates, none perhaps
is more complex, more exact, and apparently more difficult
of attainment than those which preserve all the circulating
fluids and internal organs at one uniform temperature, vary-
ing onlj^ four or five degrees Fahr., although it may be ex-
posed to temperatures varying more than a hundred degrees.
Hardly less wonderful are those cosmical and physical adjust-
ments, which, during many millions of years, have preserved
the earth's surface within those restricted ranges of temper-
ature which are compatible with an ever-increasing develop-
ment of animal and vegetable life.
Equally remarkable, also, is that other set of adjustments
leading to those perpetual surface-changes of our globe which
I have shown to be the motive power in the development of
the marvellously varied world of life; and which has done this
without ever once leading to the complete subsidence of any
of the great continents during the unceasing motions of ele-
vation and depression which have been an essential part of
that great cosmic scheme of life-development of which I am
now attempting an imperfect exposition.
That the temperature of the earth's surface should have been
kept within such narrow limits as it has been kept during the
enormous cycles of ages that have elapsed since the Cambrian
period of geology, is the more amazing when we consider that
it has always been losing heat by radiation into the intensely
cold stellar spaces ; that it has always, and still is, losing heat
by volcanoes and hot springs to an enormous extent; and that
these losses are only counteracted bv solar radiation and the
conservative effect of our moisture-laden atmosphere, which
again depends for its chief conservative effect on the enormous
202 THE WORLD OF LIFE
extent of our oceanic areas. That all these agencies should
have continued to preserve such a uniformity of temperature
that almost the whole land surface is, and has been for count-
less ages, suitable for the continuous development of the world
of life, is hardly to be explained without some Guiding Power
over the cosmic forces which have brought about the result.
1
i
i
i
CHAPTER XI
THE PROGRESSIVE DEVELOPMEITT OF THE LIFE-WORLD^ AS
SHOWN BY THE GEOLOGICAL RECORD
In order to form any adequate conception of the world of
life as a whole, of the agencies concerned in its development,
and of its relation to man as its final outcome, we must en-
deavour to learn something of its past history; and this can
only be obtained by means of the fossilised remains preserved
in the successive strata or layers of the earth's crust, briefly
termed " the geological record." In the preceding chapter I
have endeavoured to indicate the forces that have been at work
in continually moulding and remoulding the earth's surface;
and have argued that the frequent changes of the physical en-
vironment thus produced have been the initial causes of the
corresponding changes in the forms of organic life, owing to
the need of adaptation to the permanently changed conditions;
and also to the opening up of new places in the economy of
nature, to be successively filled through that divergency of
evolution which Darwin so strongly insisted upon as a neces-
sary result of variation and the struggle for existence.
But in order to appreciate the extent of the changes of the
earth's surface during the successive periods of life-develop-
ment, it is necessary to learn how vast, how strange, and yet
how gradual were those changes ; how they consisted of alter-
nate periods of not only elevation and depression, but also of
alternations of movement and of quiescence, the latter often
continuing for long periods, during which more and more
complete adaptation was effected, and, perhaps in consequence
a diminished preservation in the rocks, of the life of the period.
Thus have occurred those numerous " breaks " in the geo-
logical record which separate the great " eras " and " sys-
203
204 THE WORLD OY LIFE
terns " of the geologist. These phenomena are admirably ex-
plained in Professor James Geikie's attractive and well-illus-
trated volume on '^ Earth Sculpture or the Origin of Land
Forms," published in 1898. Here I can only attempt to
sketch in outline the successive stages of life which are ex-
hibited in the rocks, and point out some of their most striking
features with the conclusions to which they lead us.
During the latter part of the eighteenth century geologists
were beginning to obtain some detailed knowledge of the
earth's crust and its fossils, and arrived at a first rude di-
vision into primitive, secondary, and tertiary formations.
The first were supposed to represent the epoch before life ap-
peared, and comprised such rocks as granite, basalt, and
crystalline schists. 'Next above these came various strata of
sandstones, limestones, and argillaceous rocks, evidently of
aqueous origin and often containing abundant fossils of
marine, fresh-water, or terrestrial animals and plants. The
tertiary were clearly, of more recent origin, and contained
shells and other remains often closely resembling those of liv-
ing animals. It was soon found, however, that many of the
rocks classed as " primitive " either themselves produced
fossils, or were found overlying fossiliferous strata; and, by a
more careful study of these during the early part of the nine-
teenth century, the three divisions were more precisely limited
— the first or '^ Primary,'' as containing the remains of Mol-
lusca, Crustacea, and some strange fishes and amphibians;
the '' Secondary," by the first appearance of reptiles of many
strange forms ; and the ^' Tertiary," by abundance of Mam-
malia of all the chief types now existing, with others of new
and apparently primitive forms, or serving as connecting links
w^ith living groups.
It is a very remarkable fact, not sufiiciently dwelt upon in
geological treatises, that this first grouping of the whole of
the life-forms of the past into three great divisions, at a time
when our knowledge of extinct animals and plants was ex-
tremely scanty as compared with what it is now, should still
THE GEOLOGICAL RECORD 205
be in universal use among the geologists of the world. The
exact limits of each of these great divisions have been more ac-
curately determined, but the abrupt change in the life-forms,
and the world-wide unconformity in the stratification on pass-
ing from one division to the other, are as great as ever. Tlie
Primary or Palaeozoic period is still that of fishes and Am-
phibia; the Secondary or Mesozoic, that of reptiles, in
amazing abundance and variety; and the Tertiary or Caino-
zoic, that of an almost equal abundance of Mammalia, and
with a considerable variety of insects and birds.
The exceptions to the generality of this classification are
few, and are particularly interesting. Of the myriads of rep-
tiles that characterise the Secondary era, only two of the nine
orders into which they are subdivided have been found so far
back as the Permian, the latest of the Palaeozoic formations.
One of these most primitive reptiles has a near ally in the
strange, lizard-like Hatteria still surviving in some small
islands on the coast of l^ew Zealand ; while others which seem
to form connecting links with the earliest mammals may be
the ancestral form from which have descended the unique
types of the lowest living Mammalia, the omithorhynchus and
echidna of Australia.
So with the highest type of vertebrates, the mammals.
About the middle of the nineteenth century small mammalian
jaws with teeth were discovered in w^hat was known as the
dirt-bed of the Purbeck (Jurassic) formation at Swanage;
others in the Stonesfield Slate of the same fomiation; and at
a later period very similar remains were found in beds of the
same age (and also in the Cretaceous) in Xorth America.
These are supposed to be primitive insect-eating Marsupials
or Insectivora, and were all about the size of a mole or a rat;
and it is a striking example of the imperfection of the geo-
logical record, that although they occur through the whole
range of the Secondary period, from the Trias to the Cre-
taceous, their remains are still exceedingly scanty, and
they appear to have made hardly any structural progress in
206 THE WORLD OF LIFE
that enormous lapse of time. Yet directly we pass from the
Cretaceous to the Tertiary rocks, not only are Mammalia
abundant and of fairly large size, but ancestral types of all
the chief orders occur, and such highly specialised forms as
bats, lemurs, and sea-cows (Sirenia) are found in its earliest
division, the Eocene.
Either there is no record of the missing links in the Sec-
ondary formations, or, what is perhaps more probable, the
break between the Secondary and Tertiary beds was of such
enormous duration as to afford time for the simultaneous dvinsr
out of numerous groups of gigantic reptiles and the develop-
ment in all the large continents of much higher and more
varied mammals. This seems to imply that a large portion
of all our existing continents was dry land during this vast
period of time ; the result being that the skeletons of very few
of these unknown forms were fossilised; or if there were anv
they have been subsequently destroyed by denudation during
the depression and elevation of the land which we know to
have occurred.
We will now consider these great geological periods sep-
arately, in order to form some conception of the changes in
the world of life which characterised each of them.
The Primary or Pdloeozoic Era
The Palaeozoic differs from the two later eras of geology
in having no known beginning. The earliest fossils are found
in the Cambrian rocks ; they consist of a few obscure aquatic
plants allied to our Charas and Algae, and some lowly marine
animals allied to sponges, crinoids, and annelids. But there
are also many forms of shell-bearing Mollusca, which had al-
ready developed into the four great classes, lamellibranchs,
pteropods, gasteropods, and cephalopods ; while some groups
of the highly organised crustaceans were abundant, being rep-
resented by water-fleas (ostracods) and numerous large and
varied trilobites. Besides these, the curious Molluscoidea
were fairly abundant, Terebratulae now first appear, and, as
THE GEOLOGICAL EECORD 207
well as the genus Lingnla, have continued to persist through
all the subsequent ages to the present time. Great masses
of rocks stratified and imstratified exist below the Cambrian,
but have mostly been metamorphosed by internal heat and pres-
sure, and contain no recognisable organic remains.
Geologists have been greatly impressed by this sudden ap-
pearance of marine life in such varied forms and compara-
tively high organisation, and have concluded that the strati-
fied formations below the Cambrian must probably have
equalled the whole series which we now know above it. Dr.
Croll declared, that " whatever the present mean thickness of
all the sedimentary rocks of our globe may be, it must be
small in comparison with tlie mean thickness of all the sedi-
mentary rocks which have been formed " ; while Darwin says,
" Consequently, if the theory be true, it is indisputable that
before the lowest Cambrian stratum was deposited long periods
elapsed, as long as, probably longer than, the whole interval
from the Cambrian age to the present day, and that during
these vast periods the world swarmed with living creatures." ^
This view was supported by Sir Andrew Eamsay, Director-
General of the Geological Survey, who possessed unrivalled
knowledge of the facts as to the geological record. He says,
speaking especially of the fossil fauna of the Cambrian age :
" In this earliest known varied life we find no evidence of its
having lived near the beginning of the zoological series. In a
broad sense, compared with what must have gone before, both
biologically and physically, all the phenomena connected with this
old period seem, to my mind, to be of quite a recent description;
and the climates of seas and lands were of the very same kind
as those the world enjoys at the present day." -
This consensus of opinion renders it highly probable that
the existing geological record only carries us back to some-
where about the middle of the whole period during which life
has existed upon the earth.
1 Origin of Species, 6th ed. p. 286.
2proe. Roy. Soc., 1874, p. 834.
208
THE WOELD OF LIFE
Passing through the long series of Lower Silurian strata,
(now separated as Ordovician) we have fuller developments
and more varied forms of the same classes found in the Cam-
brian; but in the Upper Silurian we meet with remains of
fishes, the first of the great series of the vertebrates to appear
upon the earth. Thej are of strange forms and low type,
mostly covered with a kind of plate-armour, and apparentlv
without any lower jaw. Hence they form a separate class —
Agnatha (^^ without jaws"). They also appear to have had
no hard, bony skeleton, as the only parts fossilised are the outer
skin with its more or less armoured covering. The illustra-
tion (Fig. 39) shows one of the simpler forms, the whole sur-
FiG. 39. — Thelodus scoticiis.
From Upper Silurian, Lanarkshire. Half nat. size.
(B.M. Guide.)
face being covered with small quadrangular flattened tubercles.
The tail is somewhat twisted to show the bi-forked character.
The mouth must have been an aperture underneath the head.
Good specimens of these are rarely preserv^ed.
In another family, Pteraspidse (Fig. 40), the skin-tubercles
Fig. 40, — Pteraspis rostrata.
From Old Red Sandstone of Herefordshire. One-third nat. size. (B.M. Guide.)
are united into plates and scales, while the head is covered
with a dorsal shield, often terminating behind in a spine ;
THE GEOLOGICAL RECORD
209
and there is often a smaller shield beneath. A separate piece
forms a projecting snout.
The shields of these fishes are often preserved, while the
complete body is very rare.
Another gi'oup (Fig. 41) has the head shield continuous
Fig. 41. — Ceplalaspis murchisoni.
From Old Red Sandstone of Herefordshire. About half nat. szie.
(B.M. Guide.)
or in two pieces, while the skin-tubercles are united into vertical
plates on the sides of the body, as in the species here sho^vn,
while others have two or three rows of plates.
The highest group of these primitive fishes has the head
and fore part of the body covered with large polygonal bony
plates. As these died out in the Devonian epoch their place
was taken by true fishes, having an ossified skeleton, a movable
lower jaw, gill-covers, and pairs of pectoral and anal fins rep-
resenting the four limbs of reptiles and mammals. The ear-
liest of these were allied to our sharks ; and at each succeeding
geological stage a nearer approach was made to the higher
types of our modern fishes.
Class — Pisces
Fig. 42.— Protocercal Tail.
The primitive type of true fishes, having a lower jaw and paired fins. (B.M. Guide.)
Fig. 43. — Heterocercal (unequal-lobed) Tail.
The middle type of true fishes. (B.M. Guide.)
210
THE WOKLD OF LIFE
Fig. 44. — Homocercal (equal-lobed) Tail.
Modern type of true fishes.
The older types persist in some of the lower forms. (B.M. Guide.)
This advance in development is well indicated by the
gradual changes in the tail, as shown in the accompanying
figures (42-44). The upper one is the oldest; but it soon
became modified into the second, which in various modifica-
tions prevailed throughout the Palaeozoic and most of the Sec-
ondary periods; while the third perfectly symmetrical type
did not appear till near the end of the latter, and only became
predominant, as it is now, in the Tertiary period. Many of
the earlier forms have tails which are quite symmetrical ex-
ternally, but show a slight extension of the vertebrae towards
the upper lobe. All three forms still exist, but the third is by
far the most abundant.
In the highest Silurian beds land-plants allied to ferns and
lycopods first appear, and with them primitive scorpions. In
the succeeding Devonian and Carboniferous strata an ex-
tremely luxuriant land vegetation of a low type appeared and
covered a large part of the existing lands. This supported a
large variety of arthropods as well as true insects allied to
mayflies and cockroaches, with a great number of Crustacea.
Here, too, we come upon the next great step towards the higher
land animals, in the appearance of strange Amphibia forming
a distinct order — the Labyrinthodontia. They appear to
have outwardly resembled crocodiles or lizards, and were rather
abundant during the Carboniferous and Permian eras, dying
out in the subsequent Triassic.
That portion of the Palaeozoic series of strata from the
Silurian to the Permian, during which a rich terrestrial
vegetation of vascular cryptogams was developed, with numer-
THE GEOLOGICAL RECORD 211
ous fonns of arthropods, insects, primeval fishes and am-
phibians, comprises a thickness of stratified rocks somewhat
greater than that of the whole of the Secondary and Tertiary
strata combined. This thickness, which can ho measured with
considerable approach to accuracy, is generally supposed to
afford a fair 'proportionate indication of the lapse of time.
There is a popular impression that in these remote ages the
forces of nature were more violent, and their results more
massive and more rapidly produced, than at the present time;
but this is not the opinion of the best geological observers.
The nature of the rocks, though often changed by pressure and
heat, is in other cases not at all different from those of subse-
quent ages. Many of the deposits have all the characters of
having been laid down in shallow water, and in several cases
footprints of Amphibia or reptiles have been preserved as well
as impressions of raindrops, so exactly corresponding with those
which may be seen to-day in suitable places, that we cannot
suppose the operations of nature to have been more violent
then than now. All our great coal deposits of PalaBOzoic age
indicate long, and often repeated, but very slow depression of
large areas of land, with intervening periods of almost perfect
stability, during which dense forests had again time to grow,
and to build up those vast thicknesses of vegetable matter
which, when buried under successive rock-strata, became com-
pressed into coal-seams, usually of several feet in tliickness.
It is an extraordinary fact that in all the great continents,
including even South America and Australia, coal-fields are
more or less abundant at this period of the earth's history.
This is proved by the identity or close similarity of the vege-
tation and animal life, as well as by the position of the coal-
beds, in regard to the strata above and beneath them. It is
true that coal is also found in some Secondary and Tertiary
strata, but these beds are much less extensive and the coal is
rarely of such purity and tliickness ; while the later coal-fields
are never of such world-wide distribution. Tt seems certain,
therefore, that at this particular epoch there Avere some spe-
212 THE WOELD OF LIFE
cially favourable conditions, affecting the whole earth, which
rendered possible a rapid growth of dense vegetation in all
situations which were suitable. Such situations appear to
have been extensive marshy plains near the sea, probably the
deltas or broad alluvial alleys of the chief great rivers ; and the
special conditions were, probably, a high and uniform tem-
perature, with abundance of atmospheric moisture, and a larger
proportion of carbon-dioxide in the air than there has ever
been since.
We may, in fact, look upon this period as being the neces-
sary precursor of the subsequent rapid development of terres-
trial and aerial animal life. A dense and moisture-laden
atmosphere, obscuring the direct rays of the sun, together wdth
a superabundance of carbonic-acid gas and a corresponding
scarcity of free oxygen, would probably have prevented the
full development of terrestrial life with its magnificent culmi-
nation in such examples of vital activity as we see manifested
in the higher mammalia, and especially in the more perfectly
organised birds and insects. In this first and most widespread
of the coal-making epochs we see the results of a world-wide
and even cosmical adaptation which influenced the whole future
course of life-development; while the later and more limited
periods of coal-formation have been due apparently to highly
favourable local conditions, of which the production of our
deeper peat beds are the latest example.
If then, as I am endeavouring to show, all life development
— all organic forces — are due to mind-action, w^e must postu-
late not only forces but guidance; not only such self-acting
agencies as are involved in natural selection and adaptation
through survival of the fittest, but that far higher mentality
which foresees all possible results of the constitution of our
cosmos. That constitution, in all its complexity of structure
and of duly co-ordinated forces acting continuously through
eons of time, has culminated in the foreseen result. ISTo other
view yet suggested affords any adequate explanation ; but this
vast problem will be more fully discussed later on.
THE GEOLOGICAL EECORD 213
This earliest, but, as some think, the most extended period
of geological time, has been very cursorily touched upon, both
because its known life-forms are more fragmentary and less
generally familiar than those which succeeded them, and be-
cause the object here is to show reasons for considering it as
essentially 'preparatory for that wonderful and apparently sud-
den burst of higher life-development of which we will now en-
deavour to give some account.
The Mesozoic or Secondary Formations
When we pass from the Palaeozoic to the Mesozoic era we
find a wonderful change in the forms of life and are trans-
ported, as it were, into a new world. The archaic fishes
wholly disappear, while the early Amphibia (Labyrinthodonts)
linger on to the Trias, their place being taken by true reptiles,
which rapidly develop into creatures of strange forms and
often of huge dimensions, whose skeletons, to the uninstructed
eye might easily be mistaken for those of Mammalia, as in fact
some of them have been mistaken. The earliest of these new
types, somewhat intermediate between Amphibia and reptiles,
appear in the latest of the Palaeozoic strata — the Permian.
These are the Theriomorpha (or "beast-shaped'' reptiles),
which show some relationship to true mammals which so quickly
followed them in the lowest of the Mesozoic strata.
These early reptiles already show a large amount of speciali-
sation. Some have greatly developed canine teeth, almost
equalling those of the sabre-toothed tiger; others were adapted
to feed on the luxuriant vegetation of the period, while their
short, massive limbs made them almost as clumsy-looking as
the hippopotamus. These strange creatures were first discov-
ered in the Karoo formation of the Cape Colony, but have been
found in a few places in India, Europe, and Xorth America,
always either in the highest Primary (Permian) or lowest
Secondary formation (Trias). Pemains of allied forms have
been found in the north of England and in the Trias of Elgin,
Scotland. Their nearest survivimr relatives arc supposed to
214: THE WOKLD OF LIFE
be the monotremes (echidna and platypus) of Australia, jet in
the whole series of stratified rocks of Secondary and Tertiary
times no intermediate form has yet been discovered.
A complete skeleton of one of the largest of these beast-
shaped reptiles is represented here (Fig. 45). The body of this
strange animal was nearly seven feet long, and its small teeth
show it to have been a vegetable feeder. The total length of
some specimens was nearly ten feet, and the immense limbs
were apparently adapted for digging, so that in loose soil it
mav have been of subterranean habits. In the same forma-
tion other allied but much smaller species were found.
Along with these w^ere many creatures of the same general
type, but as clearly carnivorous as the others were herbivorous.
About a dozen distinct genera have been characterised, and as
each probably comprised several species, and as these have as
yet been all obtained from a few very limited areas, it is quite
possible that the land animals of the Cape Colony at that
early period may have been almost as numerous, as varied, and
as conspicuous as they are to-day.
The two skulls here figured (Figs. 46 and 47) are of very
different forms, and must have belonged to animals about the
Fig. 46. — Dicynodon lacerticeps (Order — Anomodontia).
From Karoo formation (Trias), South Africa. One-third nat. size. (B.M. Guide.)
size of wolves; but there were many others of various shapes
and sizes, some even equalling that of a large crocodile.
But at the same epoch, apparently, Europe and North Amer-
ica were equally well supplied w^ith these strange reptiles, Ira,
•iiopouBn.§i aq; jo aouB.iBaddv 9iqi?qo.ij — -jc -oij
(•9pinjc) 'H'a) "auids i^uoiB laaj 08 •q^Sueq; •uiniS[aa; Jo uapiBa^i eq; mox^
• ( siaudj.
-jivasnudfi uopounn^i) .iuusouiq snopocToq^ui.iQ jo iio;e[9>^s — -qo -oij
THE GEOLOGliCAL KECOiilJ lM:.
Europe till recently only a few isolated bones or fragments of
skulls bad been discovered, but about five or six years ago a
rich deposit was found on the banks of the river Dwina in
^N^orthern Kussia. Tn a large fissure of the rocks quantities
Fig. 47. — J^lusaurus felinus (Order — Anomodontia).
From Trias (South Africa). Two-thirds nat. size. (B.M. Guide.)
of nodules of very hard rock had been found, and being easy
to obtain, were broken up for mending roads; till Professor
Amalitzky from Warsaw, visiting the spot, found that each
of these nodules contained well-preserved fossils of extinct ani-
mals, which proved to be reptiles of the very same group as
those of South Africa. Some of these nodules contained a
skull; others contained the whole skeleton, these being some-
times eight feet long, and of strange forms corresponding to
the crushed or distorted body of the animal. Thenceforth
Professor Amalitzky devoted himself to the work of explora-
tion by the aid of a grant from the Imperial Academy of St.
Petersburg. The nodules are taken to Warsaw, where ihey
are carefully opened, and the fossilised bones extracted,
cleaned, and put together. Some of these are found to be
almost identical with those of South Africa; others, quite
distinct, though allied. Fig. 48 represents the skull of a huge
carnivorous reptile, which must have been about the same size
as the herbivorous Pariasauri fabundantly preserved in tho
nodules), upon which it doubtless preyed. As the skull is two
216 THE WOKLD OF LIEE
feet long, and the whole head and body about nine feet, it must
have far exceeded in size the largest lion or tiger, and prob-
ably that of any carnivorous land mammal that has ever lived.
In I^orth America these reptiles were also present in consid-
erable abundance. Some, forming the sub-order Theriodontia,
were allied to the Pariasauri, and were probably herbivorous;
while the Pariotrichida? were carnivores, as were also a very
distinct family, the Clepsydropidse. Of this latter group one
1 genus, Dimetrodon, is here figured as restored by Sir Ray
Lankester (Fig. 49). This is supposed to be allied to the liv-
ing Hatteria of New Zealand. These strange carnivorous rep-
tiles of this early period may have preyed upon numerous
herbivores which have not been preserved, as well as upon the
primitive insects and land Crustacea, which at this period were
probably abundant.
The remarkable thing is, that some hundreds of species of
varied form and size, herbivorous and carnivorous, should have
been gradually developed, arrived at maturity, and completely
died out, during the comparatively short periods of the Permian
and Trias, or the interval between them.
It is probable, however, that these transition periods really
occupied a very great length of time, since all known reptiles
seem to have originated during this era, though owing to unfa-
vourable circumstances the connecting links have rarely been
preserved. The singular Chelonia (turtles and tortoises) ap-
pear fully formed at the end of the Trias or in the earliest
Jurassic beds, as do the crocodiles, the aquatic Plesiosaurians
and Ichthyosaurians, the flying Pterodactyls, and the huge
Dinosaurs. All these have more or less obscure interrelations,
and their common ancestors cannot well be older than the
Permian, since the preceding Carboniferous offered highly
favourable conditions for the preservation of the remains of
such land animals had they existed. To bring about the modi-
fication of some primitive reptile or amphibian into all these
varied forms, and especially to bring about such radical changes
of structure as to develop truly aerial and truly oceanic rep-
-^^wy^jrw — *-« »~
~i
fUi
Fig. 48. — Skull of the gigantic Theriomorpli Carnivorous Reptile
Inostransevia.
From Northern Russia. (Length of skull, 2 feet.) Permian or Triassic age. This
animal was probably as large as a rhinoceros. (From Sir Ray Lankester's
Extinct Animals.)
Fig. 49. — Probable Appearance of the Therioniorj)!! KcitliU' Dinietroilon.
From the Permian of Texas. It was the size of a large dog. (From Sir Kay Lan-
kester's Extinct Animals.)
THE GEOLOGICAL RECORD 217
tiles, must, with smy reasonable speed of change, have required
an enormous lapse of time, yet all these had their origin seem-
ingly during the same period. Some account of the strange
animals whose abundance and variety so especially character-
ised the Secondary period will now be given.
Order — Dinosauria
Some of the best known of these reptiles have been found
in our own country, and we will therefore begin with the
Iguanodon, of which teeth and bones were found near Maid-
stone (Kent) by Dr. Mantell in the early part of the last
century, but no complete skeletons have been found. A
closely allied species from Belgium of the same age (the
Wealden) is here figured (Fig. 50). It was about thirty foot
long, and is believed to have walked chiefly on its hind feet,
and to have fed upon the foliage or fruits of good-sized trees.
As shown in the restoration of the animal in its supposed usual
attitude when alive (Fig. 51), it would stand about fourteen
feet high. The fore-limbs are comparatively small, termi-
nating in a hand of five fingers, the thumb being represented
by a bony claw. The much longer hind legs, however, have
feet with only three toes, much resembling those of running
birds, and numerous impressions of such feet have been found
in rocks of the same age, hence the group to which it belongs
has been named Ornithopoda or '^ bird-footed.'' From the
character of these it seems probable that the animal would
walk on all fours and leap with its hind legs in the manner
of a kangaroo.
The skull as shown by Fig. 52 is three and a half feet long,
and the numerous close-set serrated teeth seem well adapted
for grinding up large quantities of vegetable matter. The
deep compressed tail indicates that it may have been used for
swimming, and that the animal frequented lakes or marshes,
and perhaps escaped its enemies by taking to the water. It
appears to have had no protective armour.
Another group was named Stegosauria, " plated lizards,"
218
THE WORLD OF LIFE
from tlieir protective armour, a skeleton of whicli Is figured
(Fig. 53). It has long bony spines on the shoulders, which,
if bearing a horny covering, would have been an effective pro-
tection against beasts of prey; and this is followed by a row
Fig. 52. — Skull of I guanodon bernissartensis.
From the Wealden of Belgium. Three and a half feet long. (B.M. Guide.)
Fig. 53. — Skeleton of Armoured Dinosaur {Scelidosaurus harrisoni).
From the Lower Lias of Charmouth, Dorset. Length along spine, about 13 feet;
height as drawn, 7 feet, (B.M. Giiide.)
I— I
p
a'
Co
Co
O
3
o
a-
o
p
P
O
O
^ '
P
GO
o
p
w
O
(h
THE GEOLOGICAL RECORD
219
of bony knobs on the sides, which also probably carried spines
protecting the vital organs. A row of similar bones along each
side of the powerful tail may also indicate spines, which would
have rendered this an effective weapon against an encmv from
the rear. In another allied species, of which the skull is hero
shown (Eig. 54), there were two enormous horns above the
eyes and a smaller one upon the nose; while the margin of
Fig. 54. — Skull of Horned Dinosaur (Sterrolophus flabellatus).
From the Upper Cretaceous of Wyoming, U.S.A. (B.M. Guide.)
the bony expansion behind seems to have borne a row of spiny
plates.
As an illustration of how these huge but ratlior w(>ak vege-
table feeders ^vere protected, the above restoratiou uiny bo use-
ful, especially w^hen we remember that the species above tigured
was as bulky as a rhinoceros or elephant. It was found in
the Upper Jurassic strata of Xorth America.
We now come to some of the largest laud-auiiual> which
ever lived upon the enrth — the Snuropodn, or liznrd-footed
Dinosaur — and these were more or less amphibious. One of
220 THE WORLD OF LIFE
the most singular of these is the Brontosaunis, the skeleton of
which is here represented. It is said to have the smallest head
in proportion to the body of any vertebrate animal. Pro-
fessor O. C. Marsh, who discovered it, states that the entire
skull is less in diameter or weight than the fourth or fifth
neck vertebra, while the brain-cavity is excessively small. He
says : '^ The very small head and brain indicate a stupid slow-
moving reptile. The beast was wholly without defensive or
offensive weapons or dermal armour. In habits it was more
or less amphibious, and its remains are usually found in local-
ities w'here the animals had evidently become mired."
A creature nearly as large was the Cetiosaurus leedsi, from
the Oxford clay near Peterborough, of which the left hind limb
and the larger part of the tail are mounted in the British
Museum. It measures 10 feet 6 inches high at the hip, and
must have been nearly 60 feet long. Still larger was the Amer-
ican Atlantosaurus immanis, of w^hich only fragmentary por-
tions have been obtained; but a complete thigh-bone, 6 feet
2 inches long, is the largest yet discovered. It was found in
the Upper Jurassic strata of Colorado, U.S.A.
The largest complete skeleton is that of the Diplodocus car-
negii, now w-ell known to all who have recently visited the
British ^Natural History Museum, where a model of it is
mounted, as shown in the photographic picture of it here repro-
duced. It is SO feet in length, both neck and tail being enor-
mously long in proportion to the body. It is supposed that it
would have been unable to walk on land except very slowly,
and that it inust have lived chiefly in the water on juicy water-
weeds, which its very weak teeth, as shown in the above figure
of the skull, would alone have been such as it could graze on.
The very long neck would have enabled it to gather such food
from moderately deep water. The brain occupied the small
space between and behind the eyes (Fig. 58).
These huge reptilian herbivora, feeding in marshes, lakes,
or shallow seas, w^ere preyed upon by the numerous crocodiles
which lived throughout the same j)criods and are everywhere
Fig. od. — Probable Appearance of the Jurassic Dinosaur Stegosaurus.
The hind leg alone is twice the height of a well-grown man.
(From Sir Ray Lankester's Extinct Animals.)
1 1
THE GEOLOGICAL RECORD
221
found in the same strata. They were of varied forms and
sizes, but as they did not differ much in appearance from the
various crocodiles and alligators now living in the tropics they
V
!H
"3
o
1^
M
^^
•
--^
^'
CO
Ul
■•*»
s
2
^•w
<t)
-1^
o
<u
§
0)
00
t-
S
tH
V
S
■•^
c
<»
CO
O
P
a
l->
C3
!/>
,
O
<1
c
•rH
02
fi
^
05
3
bo
o
a
'T3
O
e-
o
o
f^
%^
>■
t^
»-»
w^
rt
•M
m
o
1
t>
1
• r^
1
CO
09
es
•
0
o
•-D
e
P<
o.
p
a>
.d
■**
a
o
M
Pm
need only be mentioned. But besides these there were true
Dinosaurs of similar shape to tlie Tguanodon, but of rather less
massive form and with strong teeth curved backward, which
222
THE WORLD OF LIFE
Avitli tliolr wicle-openlng jaws evidently adapted them to seize
and prey ujDon the larger land-reptiles. These form the Sub-
FiG. 58. — Skull of Sauropodous Dinosaur {Diplodocus) .
From the Upper Jurassic of Colorado, U.S.A. One-sixth nat. size. (B.M. Guide.)
Fig. 59. — Skull of a Theropodous Dinosaur {Ceratosaurus nasicornis).
From the Upper .Jurassic of Colorado, U.S.A. One sixth nat. size. (B.:\r. Guide.)
order Theropoda, or beast-footed Dinosaurs. The skull of one
of these here shown (Fig. 59) is more than 2 feet long, but
f.
•+-5
'T.
c
I-
4
THE GEOLOGICAL EECORD 223
no complete skeleton has been jet discovered. The allied
Megalosaurus was found by Dr. Bnckland in the Weahh'ii
beds in such abundance that he was able to piece together
enough of the skeleton to show its affinity to the Iguanodon.
Order — Sauropterygia
We now come to the group of aquatic lizards wdiich abounded
in all the seas of the Mesozoic period from the Trias to the
Chalk. They had lizard-like heads, powerful teeth, both fore
and hind limbs converted into paddles, and often with a dilated
swimming tail. They varied much in size, but were often
very large. Plesiosaurus cramptoni, from the Upper Lias of
Whitby, w^as 22 feet long, but some species from the Chalk
formation were from 30 to 40 feet long. A skull and jaws
of P. grandis, from the Kimmeridge clay, is 6 feet long, which,
if the proportions were the same as those of the species here
represented (Fig. 60), w-ould have belonged to an animal nearly
50 feet long. The whole group w^as extremely varied in form
and structure, but all w^ere adapted for preying upon such
aquatic or marsh-frequenting animals as abounded during the
same period.
Order — Ichthyopterygia
All the members of the preceding order have the paddles
supported by a complete bony foot or hand composed of five
separate fingers and connecting wrist-bones. But in the pres-
ent order the adaptation to marine life is more perfect, a dorsal
fin and bi-forked tail having been developed (Fig. 61), while
the bony skeleton of the four limbs often consists of seven or
eight rows of polygonal bones closely fitted together as shown
in the drawings here reproduced (Fig. 62 A, B). They were
also remarkable for their verv larG:e and hiffhlv oro-anised eves,
which, with the lengthened jaws and closely set sharp teeth, indi-
cate a perfect adaptation for capturing the fishes which the seas
of that age no doubt produced iu the same abundance and almost
as great variety as our own. These creatures also varied uiuch
224
THE WOKLD OF LIFE
B
in size and shape, one from the Lower Lias of Warwickshire
being 22 feet long, but detached vertebra? sometimes indicate
a much larger size. In
the older Triassic beds
smaller species are found
which were less completely
aquatic ; and these seem to
show an affinity to Am-
23hibia rather than to rep-
tiles, indicating that the
two aquatic orders may
have had independent ori-
gins.
Still later, in the Cre-
taceous formation, there
were other aquatic reptiles
quite distinct from all the
preceding, and more al-
lied to our living lizards,
having well-formed swim-
ming feet, but snake-like
bodies. These serve to in-
dicate how completely the
?'^-.?^-~?^S'H^,''''^ ^^^ and Hind (B) reptiles of the Secondary
Paddles of Ichthyosaurus intermedius. ^
From Lower Lias of Lyme Regis. One-third CpOCh OCCUpicd the plaCC
nat. size. (B.M. Guide.) n^^ ^ ^ ,^ T\r
now nlled by the J\lam-
malia, somewhat similar forms adapted for aquatic life being
again and again developed, just as the Mammalia subsequently
developed into otters, seals, manatees, porpoises, and whales.
Order — Ornithosauria
We come finally to one of the most remarkable developments
of reptilian life, the bird-lizards, more commonly known as
Pterodactyls, which accompanied all the other strange forms
of reptilian life in the Mesozoic period. They are first found
a little later than the earliest Dinosaurs, in the Lowc-r Lias of
IC
0,
o
Oj
•
a
,- — ^
u
C3
• p^
-d
fcJD
QJ
^
»— 1
0)
"rt
o
>^v
OS
«
}-^
Oi
««-<
.S
2
'^
^
ec
• ri
OJ
W
P
W
a
t^
)-H
§■
o
w
p.
O
S3
^ — '
be
O
+»
=c
c
o
c
^
1— t
• ^^
r^i.
_>>
«M
c
-4J
o
-5S
0)
"c
2
?i.
«t-i
o
<»
^
o
00
tS
0)
o
1
m
Oi
^
tr-
>
3
p
s
CO
g
s
ee
:3
"5d
ft
?►.
CO
05
O
S
P5
r*
Ph
%»
<B
;S
<»
o;
<u
e
a
,o
^
CO
p^i
CO
-4^
o
J
C3
a
=0
X
•^H
C
^
S^
tC
o
2
'S
S
•
-l-i
o
CO
u
c3
•
a
S
n
u
Ph
P<
Eh
c ^
be
;-<
—
t
— ,
TT
;-
-fc^
c
01
—
V-
IM
ec
f— 1
••r-
s
-u
3
?:
C
§
<«1
o
t)
•
OQ
■ ^
ec
be
tf
^
0/
^
a
,-*^
>v
;i^.
T
^^
^
-♦^
CO
fS:
cS
u
a.
^
^
CO
^
•— '
d
M
flH
THE GEOLOGICAL RECORD
Bavaria; but as they are, even then, fully developed, though
small, there must have been a long series of intennediate forms
which probably reached back to the Triassic if not to the
Permian era.
Fig. 63. — Skeleton of Pterodactylus spectahilis.
From the Upper Jurassic of Bavaria. Nat. size. This early form has teeth and a
very short tail, and the body was not larger than that of a sparrow. (B.M.
Guide.)
The illustration of the skeleton of one of these early forms
on this page is of the natural size (Fig. 63), Tt shows the
greatly elongated fifth finger to which the wing-membrane was
attached. In this form there were small teeth in the jaws, and
the tail was very short.
OQfi
THE WORLD OF LIFE
Fig. 64. — Restoration of a Long- Tailed Pterodactyl {Rhamphorhynchus
'phyllurus ) .
From the Upper Jurassic of Bavaria. (B.M. Guide.) Expanse of wings more than
2 feet. The long tail has a terminal web, shown in casts in fine lithographic
stone.
The above restoration (Fig. 64), shows a larger species from
the Jurassic formation, at which period they were more varied.
This had a very long tail with a dilated membrane at its tip.
Allied species, with a long pointed tail, have been found in
the Lias of Lyme Regis, and also at Whitby.
Fig. 65. — Toothless Pterodactyl {Pteranodon occidentalis) .
From the Upper Cretaceous of Kansas, U.S.A. (B.M. Guide.)
It was not till the Cretaceous period that the Pterodactyls
reached their greatest size, the species figured here having an
expanse of eighteen feet ; and these large forms have a pow-
erful but toothless beak (Fig. 65).
Fragments of bone from the English Chalk indicate an
THE GEOLOGICAL REC0RT3
227
equally large size. The backward prolongation of the head is
supposed to show that the powerful muscles required for such
immense wings were attached to the head. This is rendered
more probable by the skull, nearly 4 feet long, of another still
larger species, in which the occipital crest projects a foot back
from the head, and which Professor ^Farsli believes had a
spread of wdng of 20 or even 25 feet (Fig. 66).
Fig. 66. — Lateral View of Skull of Pteranodon longiceps.
From the Cretaceous of North America. One-twelfth nat. size. The jaws are en-
tirely without teeth. There is an enormous occipital crest (c) projecting far
behind the occiput, to which the mirscles for flight were probably attached; (a)
the nares and pre-orbital cavity; (&) the orbit. This species had an expanse
of wings of about 20 feet. (From Nicholson's Manual of Palaeontology.)
We thus see that during the Secondary epoch the great class
Reptilia, wdiich had originated apparently during the last
stages of the Primary, became developed into many special
types, adapted to the varied modes of life wdiich the higher
warm-blooded vertebrates have attained in our own time. The
purely terrestrial type had their herbivora and carnivora cor-
responding to ours in structure and habits, but surpassing them
in size; the amphibious or marsh species surpassed our largest
existing crocodiles, while the true aquatics almost exactly an-
ticipated the form and habits of our porpoises and smaller
whales. The air, too, was peopled by the strange Pterodactyls
which surpassed the bats in powers of flight, in which they
almost rivalled the birds, while they exceeded both in the enor-
mous size thev attained. Considering how rare must have been
the circumstances which led to tlie preservation in the rocks of
these aerial creatures, we may conclude, from the large number
of species known to us, that they \u\\<\ have been extremely
abundant in middle and late ^Icsozuic times, and that they
228 THE WORLD OF LIFE
occupied almost as important a place in nature as do tlie birds
now. Yet not one of the varied forms either of the terrestrial
Dinosaurs, the aerial Pterodactyls, or the aquatic Sauroptery-
gia and Ichthyopterygia — all abounding down to Cretaceous
times — ever survived the chasm that intervened between the
latest Secondary and the earliest Tertiary deposits yet discov-
ered. This is perhaps the most striking of all the great geolog-
ical mysteries.
One more point may here be noticed. The early small-
sized Pterodactyls arose just when highly organised winged
insects began to appear, such as dragon-flies and locusts, soon
followed by wasps, butterflies, and two-winged flies in Middle
Jurassic times ; from which period all orders of insects were
no doubt present in ever-increasing numbers and variety.
It is interesting to note further, that at the very same epoch
in which we find this great increase of insect life there ap-
peared the first true flowering plants allied to the Cycads, with
which they were till quite recently confounded. These also
must have rapidly developed into a great variety of forms,
since in the later Cretaceous formation in many parts of the
world true flowering plants, allied to our magnolias, laurels,
maples, oaks, walnuts, and proteaceous plants, appear in great
abundance. These seem to have originated and developed very
rapidly, since in the earliest deposits of the same formation
none of them occur.
Mesozoic Mammalia
There is perhaps nothing more remarkable in the whole
geological record than the fact of the existence of true mam-
mals contemporaneous with the highly diversified and abundant
reptile life throughout the period of their greatest development
from the Trias to the Cretaceous. They were first discovered
nearly a century ago in the Stonesfield Slate at the base of the
Great Oolite in Oxfordshire, and were described under the
names Amphitherium and Phascolotherium (Fig. 67). About
forty years later a considerable number of similar remains
Fig. 67. — Lower Jaw of Phascolotherium bucklundi.
Prom the Stonesfield Slate (Lower Jurassic), Oxfordshire. Outline fig. nat. size.
(B.M. Guide.)
c?
Fig. 68. — Lower Jaw and Teetli of IS i><i Uic other ium tricuspidcus.
From the Purbeck beds (Upper Jurassic) of Swanage. Outline fig. nat. size; c and
d being lateral and upper views of a molar tooth. (B.if. Guide.)
f.ic Vff -x.^<~' -^ — ^ ■_ .,--,, . fiiiiii I 111 I 11 ^M" -tmii
Fig. 69. — Lower Jaw oi Ti iconodon fnoidujc.
Purbeck of Swanage. Nat. size. (B.M. Guide.)
THE GEOLOGICAL RECORD 229
• — small mammalian jaws with teeth — were found in what
is termed the dirt-bed at Swanage, in the upper part of the
Jurassic formation. Two of these — Spalucotherium and
Triconodon — are here represented, and show how well thej
are preserved (Figs. 68 and G9). Another of a different type
(Plagiaulax) has been also found in a much older formation
in Somersetshire — the Rhetic or Upper Trias — and in beds
of the same age in Bavaria, near Wiirtemberg. Both these
types of jaw have been since found in considerable abundance
in the Jurassic beds of W^'oming, U.S.A. These materials
have enabled palaeontologists to decide that the former group
were really of the marsupial type, while the latter (and
earlier in time) belong to a distinct sub-class, the Multituber-
culata, from the curiously tubercled teeth, resembling those of
the Australian ornithorhvnchus. Somewhat similar teeth and
jaws have been found also in the Upper Cretaceous beds of
!N"orth America.
N^ow it is quite certain that these small mammals, so widely
spread over the northern hemisphere, must have been devel-
oped through a series of earlier forms, thus extending back
into that unknown gap between the Palaeozoic and Mesozoic
eras, and being throughout contemporaneous ^vith the great Age
of Reptiles w^e have just been considering. Yet during the
whole of this vast period they apparently never increased be-
yond the size of a mouse or rat, and though they diverged
into many varied forms, never rose above the lowly types of
the monotremes or the marsupials ! Such an arrest of develop-
ment for so long a period is altogether unexampled in the geo-
logical record.
The Earliest Birds
Birds present us with a similar problem, but in their case
it is less extraordinary because their ])reservation is so much
more rare an event, even in the Tertiary period, when we
know thev must have been abundant. The verv earliest-known
fossil bird is from the Upper Jurassic of Bavaria, and is beau-
230
THE WORLD OF LIFE
Fig. 70.— Drawing of the Fossil Lizard-Tailed Bird {Arcliceopteryx
macrura ) .
From the lithographic stone beds of Bavaria (Upper Jurassic). About one-fourth
nat. size. lu the Nat, Hist. Museum. (B.M. Guide.)
THE GEOLOGICAL KECOliD 231
tifully preserved in the fme-gi'aiued beds of lithographic stone.
The accompanying ilhistration is from an exact drawing of this
specimen (Eig. TO), in order to render more distinct the details
very faintly shown in the original. To the anatomist every
bone or fragment of a bone is recognisable ; while the mimis-
takable feathers, and the foot with the increasing number of
joints from the inner to the outer toe, are sufficient to show
that it is a true bird, notwithstanding its curiously elongated
tail feathered on each side. In this specimen there is no sign
of the head ; but fortunately another specimen has recently
been found, in which the skull is well preserved, and which
shows that the beak was armed with teeth (Fig. 71). Later
on, in the Cretaceous for-
mation of Kansas, U.S.A.,
some well-preserved aquatic
birds have been found.
One is of large size (about
1 feet high), something like
a diver, but with flat
breastbone, and therefore
probably with rudimentary Fig. 71.— Skull of Archwopteryx
wings; another, much ^ siemensi, showing Teeth.
_ From the lithographic stone (Upper Jurassic)
smaller, has long wing- of Bavaria. Xat. size. Original in the
1 1 11111 Berlin Museum. (B.]\r. Guide.)
bones and a deeply keeled
sternum. The bonv tail of
these is not much longer than in living birds, but in both the
beaks are toothed.
The main reason for the extreme rarity of bird-remains in
the Mesozoic era is, that being so light in body and plumage
they could very rarely be presei'\Td. Those tliat died in or
on the margins of rivers or lakes, or wdiich fell into the water,
would be at once devoured bv the fishes or the aquatic or aerial
reptiles which seem to have swanned everywhere.
232 THE WORLD OF LIFE
Concluding Remarks on Mesozoic Life-Development
The remarkable series of facts wliicL have now been sum-
marised, and which have been largely due to researches in
Xorth America, South Africa, and Europe during the last
twenty or thirty years, are of such a nature that they seem
to call for some cosmical explanation similar to that suggested
to account for the vast development of cryptogamous vegetation
towards the close of the Palseozoic era. The facts are in many
respects strikingly parallel. We find in the Carboniferous
series of rocks a storing-up of vast masses of vegetable matter
in the form of coal, which is unique in the whole past history
of the earth, and this was at a time when the only land verte-
brates were archaic forms of amphibians. Almost immediately
after the deposit was completed true reptiles appeared all over
the earth, and rapidly develoj^ed into that " Age of Eeptiles "
which is perhaps the greatest marvel of geological history.
Birds and Mammalia also started into life, apparently branch-
ing off from some common stock with the reptiles. Then,
during that blank in the record separating the Secondary from
the Tertiary era, the whole of this vast teeming mass of rep-
tilian life totally disappeared, with the two exceptions of the
crocodiles and the tortoises, which have continued to maintain
themselves till our own day, w^hile true lizards and snakes,
which are not known in earlier times, became the predominant
forms of reptilian life. It was during the same blank period
of the geological record that mammals and birds sprang into
vigorous and diversified life, just as the reptiles had done
during the blank between the Primary and Secondary eras.
To complete the great series of life-changes (perhaps as a nec-
essary preparation for them), plants underwent a similar trans-
formation; the prominent Cryptogams, Conifers, and Cycads
of the Secondary era gave way towards its close to higher flow-
ering plants, which thenceforth took the first place, and now
form probably fully 99 per cent of the whole mass of vegeta-
OJ
01
<*-<
:c
■<t
•■».-
c
a
a
•rS-
>*
a
o
~
^
m
o
^
c3
•^
^
o
o
<i
to
I—I
s
CQ
y^
5
l?>i>
£
P
^3*
»*<•
"^
"5
o
«,, ^
■ ^H
^i^
^
a
§■
^
C
0)
>
~^_j
K'
•4—*
O
1
k>
'u
S
p.
«
•^^
t>
CO
c
o
'>!
K
a
I-
^
<»
a)
p— 1
o
r
1— 1
a
o
THE GEOLOGICAL EECOKD 233
tion, with a variety of nourishing products, in foliage, fruit,
and flower, never before available.
Now here we have a tremendous series of special develop-
ments of life-forms simultaneous in all parts of the earth,
affecting both plants and animals, insects and vertebrates,
whether living on land, in the water, or in the air, all contem-
poraneous in a general sense, and all determining the transi-
tion from a lower to a very much higher grade of organisation.
Just as in the first such great step in advance from the '' age
of fishes " to the '' age of reptiles " we see reason to connect
it with the change from a more carbonised to a more oxygen-
ated atmosphere, produced by the locking up of so much carbon
in the great coal-fields of the world ; so, I think, the next groat
advance was due to a continuation of the same process by a
different agency. Geologists have often remarked on the pro-
gressive increase in the proportion of limestone in the later
than in the earlier formations. In our own country w^e see a
remarkable abundance of limestone during the Secondary era,
as shown in our Lias, Oolites, Portland stone, and Chalk rocks ;
and somewhat similar conditions seem to have prevailed in
Europe, and to a less extent in Xorth America. As limestone
is generally a carbonate of lime, it locks up a considerable
amount of carbon which might otherwise increase the quantity
of carbonic acid in the atmosphere ; and as lime, or its metallic
base, calcium, must have formed a considerable portion of the
original matter of the earth, solid or gaseous, the continued
formation of limestone through combination with the carbonic
acid of the atmosphere must have led to the constant diminu-
tion of that gas in the same way that the formation of coal
reduced it.
It seems probable that when the earth's surface was in a
greatly heated condition, and no land vegetation existed, the
atmosphere contained a much larger proportion of carb(m-
dioxide than at present, and that a continuous reduction of
the amount has been going on, mainly through the extraction
234 THE WOKLD OF LIFE
of carbon from the air by plants and from the water by marine
animals and by chemical action. The superabundance of this
gas during the early stages of the life-world facilitated the
process of clothing the land with vegetation soon after it ap-
peared above the waters; while its absorption by water was
equally useful in rendering possible the growth of the calcare-
ous framework or solid covering of so many marine animals.
With the progressive cooling of the earth and the increased
area of land-surface, more and more of the atmospheric carbon
became solidified and inactive, thus rendering both the air and
the water better fitted for the purposes of the higher, warm-
blooded, and more active forms of life. This process will, I
think, enable us partially to understand the fundamental
changes in life-development which characterised the three great
geological areas; but it does not seem sufficient to explain tbe
very sudden and complete changes that occurred, and, more
especially, the almost total extinction of the lower or earlier
types just when they appear to have reached their highest and
most varied structure, their greatest size of body, and their
almost world-wide distribution. Before attempting a solution
of this difficult problem an outline must be given of the latest,
and in some respects the most interesting, of the geological
eras — the Tertiary, or, as more frequently termed by geolo-
gists, the Cainozoic.
CHAPTER XII
LIFE OF THE TERTIARY PERIOD
Directly we pass from the Cretaceous into the lowest of the
Tertiary deposits — the Eocene — we seem to be in a new
world of life. Xot only have the whole of the gigantic Dino-
saurs and the accompanying swimming and flying reptiles
totally disappeared, but they are replaced in every part (tf the
world by Mammalia, which already exhibit indications of being
the ancestors of hoofed animals, of Carnivora, and of Quadru-
mana.
Order — Ungulata
In the Lower Eocene strata of ISTorth America and Europe,
the sub-order Condylarthra is well represented. These were
primitive, five-toed, hoofed animals which, Dr. A. Smith Wood-
ward tells us, '" might serve well for the ancestors of all later
Uiigulata." One of these, Phenacodus primcevus, was found
in the Lower Eocene of Wyoming, U.S.A., and was about 4
feet long exclusive of the tail (see Eig. 72). Considering that
this is one of the very earliest Tertiary mammals yet discov-
ered, it is interesting to note its comparatively large size, its
graceful form, its almost full series of teeth, and its large five-
toed feet; affording the starting-point for diverging modifica-
tion into several of the chief types of the higher mammalia.
So perfectly organised an animal could only have been one of
a lono^ series of forms brido:inc: over the 2:reat c'ulf between
it and the small rat-like mammals of the ^lesozoic period.
Another sub-order is the Amblypoda, of which the Corypho-
don of Europe and Xorth Americn is one of the best known.
This was about 6 feet long, and was first obtained from our
235
206
THE WORLD OF LIFE
London Claj. It had a heavy body, five-toed stumpy feet,
and a complete set of 22 teeth in each jaw adapted for a vege-
table diet ; but no defensive tusks or horns. Other allied spe-
cies were much smaller, and all were remarkable for a very
small brain.
But a little later, in the Middle Eocene of North America,
they developed into the most wonderful monsters that have ever
Fig. 73. — Uintatherium ingens.
Eocene of Wyoming, U.S.A. One-thirtieth nat. size. (B.M. Guide.)
lived upon the earth — the Dinocerata or '^ terrible-horned "
beasts. These had greatly increased in size; they often had
large tusks in the upper jaw ; and horns of varied forms and
sizes were developed on their heads. The tusks were some-
times protected by a bony flange projecting downwards from
the lower jaw immediatelv behind it, as well sho^vn in the
figure here given of Uintatherium ingens. This animal must
have been about 11 feet long and nearly 7 feet high; and if
the six protuberances of the skull carried horns like our
rhinoceroses, it must, indeed, have been a '' terrible '' beast,
LIFE OF TERTIARY PERIOD
The imperfect skull of another species (Fig. 74) shows even
larger the honj horn-cores presenting all tlie appearance of
having carried some kind of horns. This seems the more
probable, as many of the species had no tusks, and in that case
mere rounded bony protuberances would have been of little
Fig. 74. — Uintatherium cornutum.
From the Middle Eocene of Wyoming, U.S.A. (Nicholson's Palaeontology.)
protective use. Figure 75 (on p. 238) represents the skeleton
of one of the largest species without tusks. From the scah^
given, it must have been 11 or 12 feet long and nearly 8 feet
high.
Professor Marsh informs us that these strange-homed ani-
mals have been found onlv in one Eocene lake-basin, in
Wyoming, U.S.A. He says:
"These gigantic beasts, which nearly equalled the elephant in
size, roamed in great numbers about the borders of the anciout
238
THE WOKLD OF LIFE
tropical lake in which many of them were entombed. This lake-
basin, now drained by the Green Eiver, the main tributary of the
Colorado, slowly filled up with sediment, but remained a lake so
long that the deposits formed in it during Eocene time reached a
LIFE OF TERTIAEY PEETOD 239
vertical thickness of more than a mile. ... At the present
time this ancient lake-basin, now 6000 to 8000 feet above the sea,
shows evidence of a vast erosion, and probabl}^ more than one-half
of the deposits once left in it have been washed away, mainly by
the action of the Colorado River. What remains forms one of
the most picturesque regions in the whole West, veritable mauvaises
terres, or bad lands, where slow denudation has carved out cliffs,
peaks, and columns of the most fantastic shapes and colours. This
same action has brought to light the remains of many extinct
animals, and the bones of the Dinocerata, from their great size,
naturally first attract the attention of the explorer."
As regards the mental powers of these strange animals, Pro-
fessor Marsh saj's:
" The brain-cavity of the Uintatherium is perhaps the most re-
markable feature in this remarkable genus. It shows us that the
brain was proportionately smaller than in any other known mam-
mal, recent or fossil, and even less than in some reptiles. It is, in
fact, the most reptilian brain in any known mammal. In U. mira-
bile (one of the large- tusked, horned species) it could apparently
have been drawn through the neural canal of all the presacral
vertebrae." "^
It was, in fact, a small oval mass of about the same diameter
as the spinal cord !
One other strange form which may belong to the earliest
ungulates has been found in the Upper Eocene of Egypt, and
forms a new suborder, Barjpoda. It is known from a very
complete skull (Fig. 76), which is remarkable for the very
regular set of teeth, as well as for the wonderful horn-cores,
two small at the back and two enormous ones projecting in
front. The skull is nearly 3 feet long, and the larger horn-
cores about 2% feet ; and as these certainly carried true horns
they probably surpassed any of the Dinocerata. Large quan-
tities of detached bones have also been obtained, sufficient to
show that the creature was an ungulate of elephantine dimen-
sions and altogether unique in appearance. This creature hail
a somewhat larsjer brain thnn the great American ungulates,
240
THE WORLD OF LIFE
and has affinities with a curious little existing animal, the
hyrax.
Fig. 76. — Skull of Arsinoitherium zitteli.
From the Upper Eocene of the Fayoum, Egypt. One-twelfth nat. size.
(B.M. Guide.)
Order — Camivora
These can also be traced back to middle or late Eocene
times both in l^orth America and Europe. They were mod-
erate-sized animals, forming a distinct sub-order, Creodonta,
the skeleton of one of which is shown in Fisr. 77. Thev had
flesh-eating teeth, but more like those of the carnivorous mar-
supials of Australia than of our living carnivores, with a type
of skeleton showing considerable litrhtness and activity. Some
of the species were as large as lions.
LIFE OF TERTIAEY PERIOD 241
Some of the older remains in South America, called Sparas-
sodonta, are believed to belong to the same or an allied sub-
order. They occur in beds of Lower Miocene age in Pata-
gonia ; and Mr. Lydekker holds them to be " undoubtedly
marsupials," allied to the Dasyuridic of Australia. One of
these has been named Prothylacinus, from the resemblance of
its jaw to that of the Tasmanian wolf (Thylacinus australis).
Other small species forming a distinct family, Microbiothe-
ridie, he also thinks were probably " minute polyprodont mar-
supials of Australian type." ^
In the later (upper) beds of the Eocene formation and the
early or middle Miocene, ancestral forms of many of our Mam-
malia have been found both in Europe and Xorth America ;
but these are so numerous, and their affinities in some cases
so obscure, that only a few of the prominent examples need
be given. One of these, whose skeleton is figured on page 243,
belongs to the family Anthracotheridae, which has affinities
with the pigs and the hippopotami, of which it seems to be
an ancestral form. The fossil remains of this group are found
in deposits of middle Tertiary age all over the northern hemi-
sphere. They have two, three, or four separate toes, and teeth
much like those of swine.
Another family, the Anoplotheridae, contains a variety of
animals w^hich seem to be ancestral forms of the ruminants.
The genus Anoplotherium (Fig. 79) was one of the most re-
markable of these in having a full and continuous set of teeth
without any gaps, like that of the Arsinoitherium already
figured.
1 Geog. Hist, of Mammals, pp. 111-112. From these facts and otliers re-
ferred to in my preceding chapter, Mr. Lydekker thinks that " it is difficnlt
to come to any other conclusion than that the ancestors of the Santa Crucian
polyprotodont marsupials reached the country either by way of the Antarc-
tic continent or by a land-bridge in a more northern part of the Pacific."
To avoid a break of connection in the present exposition, I have briefly
stated some of the difTieuliies in the way of such a theory in an Ap-
pendix to this chapter. Those who wish to see the whole subject of the
" Permanence of Oceanic and Continental Areas " more fully discussed are
referred to my volumes on Darwinism and Island Life.
242
THE WORLD OF LIFE
An allied family, Oreodontidse, somewhat nearer to rumi-
nants, but with four-toed feet, were very abundant in Xorth
America in Miocene times. They were remotely allied to
deer and camels, and were called by Dr. L-eidy " ruminating
hogs." They seem to have occupied the place of all these
LIFE OF TEKTIAEY PEEIOD
243
animals, six genera and over twenty species havlnp: lieen de-
scribed, some of which survived till the earlv Pliocene.
The family Pala^otheridnc was also abundant during tho
244
THE WORLD OF LIFE
same period in Europe, and less so in !N"orth America. As
shown in the restoration in Fig. 80, it somewhat resembled
the tapir; but other genera are more like horses, and show a
series of gradations in the feet towards those of the horse-
tribe, as shown bj Hnxley's figures reproduced in my Dar^vin-
ism.
The Origin of Elephants
Till quite recently one of the unsolved problems of palaeon-
tology was how to explain the development of the Proboscidea
or elephant tribe from other hoofed animals. Hitherto extinct
species of these huge beasts had been found in a fossil state
as far back as the Miocene (or middle Tertiary) in various
parts of Europe, Asia, and Xorth America ; one species, the
mammoth, being found ice-preserved in Arctic Siberia in great
quantities. Some of these w^ere somewhat larger than existing
elephants, and several had enormously large or strangely curved
tusks; but, with the exception of Dinotherium, which had
the lower jaw and tusks bent downwards, and Tetrabelodon,
with elongated jaws and nearly straight tusks, none were very
different from the living types and gave no clue to their line
of descent. But less than ten years ago a number of fossils
have been obtained from the middle and higher Eocene beds
of the Fayoum district of Egypt, which give the long-hoped-for
missing link connecting the elephants with other ungulates.
The most primi-
tive form now discov-
ered was about the
size of a very large
dog, and its skull
does not differ very
strikin2:lv from those
of other primitive
ungulates. It has,
Fig. 81. — Skull of Moeritherium lyonsi. however some slie'ht
From the Middle Eocene cf the Fayoum, Egypt. One- , . '. . , ^ ,
seventh nat. size. (B.M. Guide.) peculiarities whlch
Fig. 7!). — Anoplotherium commn/tie.
Upper Eocene (Paris; also at Binstead, Isle of Wight.) From Nicholson's
Palaeontology.)
This animal was about the size of an ass, and was especially remarkable fur its
continuous set of 44 teeth, there being no gap in the series. No livins mammal
except man has this characteristic. It is supposed to have been a highly spe-
cialized enrly type which has left no direct descendants.
Fj(;. 80. — /'(ilaotherium ntogntini.
from the Upper Eocene of Paris and the Isle of "Wight. (Nicholson's PahuDntology.)
The numerous species of Pala?otlierium were three-toed animals bavins resembbmces
to horses, tapirs, and llamas. The species here figured (as restored by Cuvier)
was about the size of a horse, but it is now known that the neck was consid-
erably longer than here shown.
LIFE OF TEETIARY PERIOD 245
show a connection with the Proboscidea. These are that the
nasal opening is near the end of the snout, indicating, prohably,
the rudiment of a proboscis; the back of the skull is also thick-
ened and contains small air-chambers, the first step towards the
very large air-chambers of the elephant's skull, whose purpose is
to afford sufficient surface for the powerful muscles which sup-
port the weight of the tusks and trunk. The teeth show two
short tusks in front in the upper jaw in the same position as the
tusks of elephants, while the lower jaw or chin is lengthened
out and has two incisor teeth projecting forward. The molar
teeth show the beginning of the special characters which dis-
tinguish the huge grinding teeth of the elephants. This crea-
ture was named MoerWierium lyonsi; and its remains have
been found in great abundance along with those of both land
and sea animals, shoAving that they were deposited in what
was then the estuary of the ISTile, though now far inland.
Somewhat later, in the Upper Eocene, another group of
animals, the Palseomastodons, have been found, showing a con-
siderable advance (see Diagram, Fig. 82). They vary in size
from a little larger than the preceding to that of a small ele-
phant. The skull is very much modified in the direction of
some of the later forms. After these come the Tetrabelodons
from the Miocene beds of France and North America, and the
Pliocene of Germany. These w^ere more like elephants in
their general form, though their greatly elongated lower jaw,
bearing incisor teeth, seem to be developing in another direc-
tion. In Tetrahelodon longirostris, however, we see the lower
jaw shortened and the incisor teeth greatly reduced in size;
thus leading on to the true elephants, in which these teeth
disappear.
The skeleton of Tetrahelodon angustidens shows the lower
tusks sliorter than the upper ones, but in the fine specimen
moimted in the Paris Museum, and photographed in Sir Ray
Lankester's Extinct Animals, both are of the same h^igth,
and the upper pair curve slightly (hnvnwards on each side of
the lower pair; and they are thus shown in the suggested
246
THE WOKLD OF LIFE
Recenl
Pleistocene ELE PHA3
( short chinj
Ufiper Pliocene
Lower Pliocene
Upjier Miocene
TETRABELODON
[LONGIROSTRrS STACE]
(shortening chinj
Middle Miocene TETRABELODON
fANCUSTTDENS STAGE]
lower Miocene (long chinj
l/frper Oligocene
Migration from Africa
into EuTvp.e -Asia
Imer Oligocene?
Upfier Eocene
MiddleBocene
Lower Eocene
PALAEOMASTODON
^lengthening chinj
MOERlTHEKrUM
(short chin)
Fig. 82. — Diagrams showing Increase of Size and Alteration in Form of
Skull and Teeth of the Proboscidea since Eocene Time. (B.M. Guide.)
Fig. 83. — Skeleton of Tetrahelodon luigustidens.
From the Middle Eocene of Sansaus, France. (B.M. Guide.)
4
4-i
i
A
.;■ V
•'*®*v,, '^^
""^N,
■•>- --^j>-
■ ^-»- .
»AX
Fig. 84. — Probable Appearance of Tetrahelodon (HKjustidens.
/From Sir Ray Lankester's Extinct Animals.)
LIFE OF TERTIARY PERIOD
247
appearance of the living animal, here reproduced from his book.
(Fig. 84.) The trunk could not therefore have hung down
as in the modern elephants, and it seems hardly likely that
with such tusks a trunk would have been developed. If a short
one had been formed it would probably have been for the
purpose of drinking and for pushing food into the mouth side-
ways. It is most interesting to see how the difficulty was
Fig. 85. — Skeleton of Mastodon Americanus.
From the Pleistocene of Missouri, U.S.A. Length, 20 feet; height, 9% feet.
(B.M. Guide.)
overcome. In the next stage both pairs of tusks have become
straightened out, the lower ones much reduced in length and
the chin also somewhat shortened. That this process went on
step by step is indicated by the ^lastodons, which are elephants
with a simpler form of teeth, and a pair of tusks like all living
and recently extinct elephants (see Fig. 85). But when very
young the American Mastodon had a pair of short tusks in the
lower jaw, which soon fell out. In the character of its teeth
generally, the Mastodon agrees with Tetrabelodon (wliich was
originally classed as a Mastodon) ; and there are Indian extinct
248 THE WORLD OF LIFE
species which show other stages in the reduction of the lower
jaw.
We have here, therefore, a most remarkable and very rare
phenomenon, in which we are able to see progressive evolution
upon what seems to be a wrong track which, if carried further,
might be disastrous. Usually, in such cases, the too much
developed or injuriously developed form simply dies out, and
its place is supplied by some lower or less modified species which
can be more easily moulded in the right direction. But here
(owing probably to some exceptionally favourable conditions),
after first lengthening both lower jaw and lower tusks to keep
pace with the upper ones, a reversal of the process occurs,
reducing first the lower tusks, then the lower jaw, till these
tusks completely disappeared and the lower jaw was reduced
to the most useful dimensions in co-ordination with a greatly
lengthened and more powerful trunk. Although in this case
the gaps are still rather large, there can be no doubt that we
have here obtained a view of the line of development of the
most remarkable land mammals now living from a small gen-
eralised ungulate mammal, as indisputable and as striking as
that of the horses from the little five-toed Eohippus of the
American Eocene.
It may be here mentioned that the huge American Mas-
todon has been found in the same deposits with stone arrow-
heads, and was undoubtedly hunted by early man; as was also
the huge mammoth whose beautifully curved tusks form its
chief distinction from the living Indian elephant (Eig. 86).
This species is abundant in the frozen mud at the mouths
of the Siberian rivers; and in some cases the whole body is
preserved entire, as in an ice-house, and the flesh has been
sometimes roasted and eaten by the natives. Remains of
skeletons have been found in our own country and over a large
part of Northern Europe and Asia ; while its portrait has been
drawn from life by prehistoric man, either upon the tusks
themselves or upon the flat portions of the horns of reindeer
which he hunted for food.
LIFE OF TERTIAEY PERIOD
249
5 «
Co 03
a. e
^ CD
^ w
TO -
<— I M
<o
<4-i ,d
o **
o
4)
(4
CS
a>
a
I a
00 o
u
o
rT a
1—1 o
EC4
Tertiary Mammals of South America and Australia
ISTo part of the world has so many distinct groups of !Mam-
malia peculiar to it as South America, among wliioh the most
remarkable are the sloths and the armadillos; and all of tlicm
are found fossil in the middle or late Tertiary or the Pleisto-
cene, from Brazil to Patagonia, and are often represented by
strange forms of gigantic size. Some account of these will now
be given. DarAvin was one of the first collectors of these
fossils on his voyage in the Beagle, and during the la:^t twenty
250
THE WOKLD OF LIFE
<s!
<D
a
<s
o
o
• ^4
^
%t
«
P<
a
•
Co
13
y*-**.
•>?>
a>
CO
^
■^
^
o
■p-i
to
s
1-"
C5
l»*..i
S-
O
g*
Si
6
o
»«
S
o
Pk
05
si
O
Cj
«4-l
o
^
>.
<J
0)
a
«4-l
o
O
CT>
a>
C
, ^
1-^
O"
-fc^
;3
OQ
T3
I
<4H
p
O
^
1
•
Ol
t^
c
>
CO
o
-^
• rH
•
o
03
s
a
f^
O
c3
1
a
p4
p<
or tliirty years niimerous travellers and residents, especially
in Argentina, have more thoroughly explored the deposits of
LIFE OF TERTIAKY PEFaOD 251
the pampas of various ages. Their great richness and im-
portance may be indicated by the following enumeration of
the chief orders of Mammalia represented in them.
Of the Peimates (or monkeys) all the remains are of the
peculiar American families Cebidas and Ilapalida:', with one
extinct genus of the fonner. Bats (the order Chiroptera) are
abundant, with several peculiar genera. The Insectivora arc
very rare in South America, but a fossil has been found sup-
posed to belong to the peculiar West Indian family Solenodon-
tidge. The Carnivora are chiefly represented by fossils of the
American family Procyonidse (comprising the racoons and
coati-mundis), of which several extinct genera have been ol>-
tained. The hoofed animals (Ungulata), which, from tlieir
great abundance in a living state in every part of the world,
and their habit of living together in great herds often of many
thousands, have been most frequently preserved in a fossil
state, are here represented not only by all the chief forms that
still inhabit the country, but also by some which are now
only found in other continents, as well as by many which arc
altogether extinct. Among the former the most interesting
are true horses of the genus Equus, as well as two peculiar
genera of ancestral Equidge, distinct from those so abundant
in I^orth America. There are also several ancestral forms
of the Llama tribe, one of which, Macraiichenia patacJionica,
was as large as a camel; and there are others so distinct as to
form a separate family Proterotheriidse.
Another sub-order, Astrapotheria, were more massive ani-
mals, some of which equalled the rhinoceros in size. They
consist of two distinct genera, only found in the Patagouian
deposits of Mid-Tertiary age.-^
Still more remarkable is another group — the Toxodontia —
sometimes exceeding the rhinoceros in bulk, but with teeth
which approached those of the Rodentia; of these there are
various forms, which are grouped in three distinct families.
The skeleton of one of the most remarkable of this group is
iLydekker's Geographical History of Mammals, p. 81.
252 THE WOELD OF LIFE
shown in Fig. 87. Yet another distinct sub-order, Pyrotheria,
which in its teeth somewhat resembled the extinct European
Dinotherium, and which had a large pair of tusks in the lower
jaw is found in the earlier Tertiary strata of Santa Cruz in
Patagonia. The elephants also had a representative among
these strange monsters in the form of a species of Mastodon,
a genus also found in North America.
The very numerous and peculiar South American rodents
commonly called cavies, including the familiar gniinea-pig, are
well represented among these fossils, and there are many ex-
tinct forms. Most of these are of moderate size, but one,
Megamys, said to be allied to the viscachas, is far larger than
any living rodent, about equalling an ox in size.
Perhaps more remarkable than any of the preceding are
the extinct Edei^tata which abound in all these deposits. The
entire order is peculiar to America, with the exception of the
scaly ant-eater of Asia and the aard-vark of South Africa, and
there is some doubt whether these last really belong to the same
order. The living American edentates comprise three fam-
ilies, generally known as sloths, ant-eaters, and armadillos,
each forming a well-marked group and all with a fair number
of distinct species. But besides these, two extinct families
are known, the Glyptodontidse and the Megatheriidse, the
former being giant armadillos, the latter equally gigantic ter-
restrial sloths. Both of these lived from the Miocene period
almost to our own time, and they are especially abundant in
Pliocene and Pleistocene deposits. Some of the extinct forms
of armadillo were very much larger than any now living; but
it is among the Glyptodonts, which had a continuous shield
over the whole body, that the largest species occurred, the shell
being often 6 or 8 feet long. The skeleton of one of these is
represented by Fig. 88. One of the most recent (Dsedicurus)
was 12 feet long, of which 5 feet consisted of the massive
armoured tail, which latter is believed to have borne a number
of movable horns. The earlier fossil species were of much
smaller size, and, though far more abundant in the south, a
LIFE OF TEETIARY PERIOD
few of them have been found in the Pliocene deposits of Texas.
The extinct ground-sloths arc even more remarkable, since
254 THE WORLD OF LIFE
they were intermediate in structure between the living sloths
and the ant-eaters, but adapted for a different mode of life.
Almost all are of large, and many of gigantic size. The Mega-
therium, which was discovered more than a century ago, was one
of the largest, the skeleton (represented by a cast in the British
Museum) being 18 feet long. Their massive bones show enor-
mous strength, and they no doubt were able to uproot trees,
by standing erect on the huge spreading hind feet and grasping
the stem with their powerful arms, in order, to feed upon the
foliage, as shown in the illustration (Fig. 89). The jaw-bones
are lengthened out, indicating extended lips and probably a
prehensile tongue with which they could strip off the leaves.
An allied genus, Mylodon, which is somewhat smaller, has
been found also in Kentucky in beds of the same age, the
Pleistocene.
What renders these creatures so interesting is that they sur-
vived till a very recent period, and that they were contemporary
with man. Both human bones and stone implements have
been found in such close association with the bones or skele-
tons of these extinct sloths that they have been long held to
have lived together. But a more complete proof of this was
obtained in 1897. In a cavern in Patagonia, in a dry powdery
deposit on the floor, many broken bones of a species of Mylodon
were found ; and also several pieces of skin of the same animal
showing marks of tools. Bpnes of many other extinct animals
were found there, as well as implements of stone and bone,
remains of fires, and bones of man himself. Among the other
animal remains were those of an extinct ancestral horse, and
on some of the bones there were found shrivelled remains of
sinews and flesh.
Allied forms are found in older deposits, as far back as the
Miocene, but these are all of smaller size. They probably
ranged all over South America, and the two genera Megathe-
rium and Mylodon occur also in the most recent deposits of
the southern United States. The numerous skeletons in the
pampas of Argentina are usually found on the borders of old
Fig. 89. — Probable Appearance of the (iiant Ground-Sloth
( Megatherium gigan icnui ) .
As large as an elephant. Found in the Pleistocene gravels of South America
(From Sir Ray Lankester's Extinct Animals, p. 172.)
Vic. 'JU. — MyUxlon robust ufi.
From the Pleistocene of South America. ( Nicholson s Palii'ontohtpy. )
J
J
LIFE OF TERTIARY PERIOD 255
lakes and rivers, in the positions in which they died. Thrv
are supposed to have perished in the mud or quagmires whih-
o
3
o
^ to
'y 05
o 2
^
o
til ^
o
o
O ja
c a>
.2 -S
3
c:
2 a
S
attempting to reach the water for drink during dry seasons,
great droughts being prevalent in the district; but when these
256 THE WOKLD OF LIFE
large animals lived there must have been much more woody
vegetation than there is now. During the voyage of the Beagle,
Darwin collected a large quantity of these interesting fossils,
as described in his JSTaturalist's Voyage round the World (chap,
v.). The skeleton and outline figure of a Mylodon shown in
Fig. 90 was 11 feet in total length, but other species were
larger.
A remarkable extinct genus, Scelidotherium, of which the
complete skeleton is shown in Fig. 91, was about 10 feet long,
and has less massive limbs than the Megatherium or Mylodon,
and more elongated jaws. In some respects it approached the
ant-eaters, and was probably, like them, terrestrial in its habits.
About twelve distinct genera of these ground-sloths are now
known, comprising a large number of species. They ranged
all over South America and into the warmer parts of North
America, and before the immigration of the horse and the
sabre-toothed tiger in Pleistocene times, they must have con-
stituted the larger and more important portion of the mam-
malian fauna of South America.
Extinct Mammals of Australia
The existing Australian mammals, although of varied form
and structure, are almost all marsupials, the only exceptions
being the aerial bats, and small rodents allied to rats, which
latter might have entered the country by means of floating
timber or trees from the nearest islands. These two orders
are therefore of little importance geographically, although by
counting the species it may be made to appear that the
higher mammals (Placentalia) are nearly as numerous as the
lower (Marsupialia). The wild dog, or dingo, is also appar-
ently indigenous, but it may have been introduced by early
man, as may some of the rodents. It is unfortunate that the
deposits of Tertiary age in Australia seem to be very scanty,
except recent gravels and alluvial muds, and none of these
have produced fossils of Mammalia except in caves and dried-
up lakes, which are all classed as of Pleistocene age. These,
LIFE OF TERTIARY PERIOD
2:.7
however, are very productive in animal remains wliidi arc
extremely interesting.
They consist of many living species, but with them numljers
of extinct forms, some of gigantic size, but all undoul)t(Mlly
allied to those living in Australia to-day. Thus, bones of
kangaroos are found ranging in size from that of the smallest
living species np to that of a donkey, and sometimes of verv
distinct forms and proportions. But with theso have been
found a huge wombat, the size of a large rhinoceros, of which
the skull is here represented (Fig. 92). The complete skele-
FiG. 92. — Skull of an Extinct Marsupial, Diprotodon australis.
From the Pleistocene of Queensland and South Australia. With a man's skull, to
show comparative size. (B.M. Guide.)
ton has been quite recently obtained from Lake Callabonna in
South Australia. It is found to be 12 feet long measured
along the vertebrae, and 6 feet 2% inches high. As it has been
found in various parts of the continent, it was probably abun-
dant. Another smaller animal of somewhat similar form
was the Xototherium, which was found in Queensland, to-
gether with the Diprotodon, about fifty years ago. A large
phalanger was also found, which Professor Owen called the
pouched lion {Tliylacoho carnifex), but it is doubtful whether
258 THE WORLD OF LIFE
it was carnivorous (see Fig. 93). True carnivorous mar-
supials allied to the ^' Tasmanian wolf" (Thylacinus) and the
Tasmanian devil {Sarcopliilus) are also found.
Fig. 93. — Skull of Thylacoleo carnifex.
From the Pleistocene of Australia. One-fifth nat. size. (B.M. Guide.)
How and when the marsupials first entered Australia has
always been a puzzle to biologists, because the only non-Aus-
tralian family, the opossums, are not closely allied to any of
the Australian forms, and it is the opossums only which have
been found in tlie European early Tertiaries. But recent dis-
coveries in South America have at length thrown some light
on the question, since the Santa Cruz beds of Patagonia (Mid-
dle Tertiary) have produced several animals whose teeth so
closely resemble those of the Tasmanian Thylacinus that Mr.
Lydekker has no doubt about their being true marsupials allied
to the Dasvurid^e. There is also, in the same beds, another
distinct f amilv of small mammals — the Microbiotheridge of
Dr. Ameghino — which, from a careful study of their denti-
tion, are also considered by Mr. Lydekker to be " polypro-
todont marsupials of an Australian type." ^
But even more important is the discovery of living mar-
supials of the Australian rather than the American type in the
very heart of the South American fauna. In 1863 a small
mouse-like animal of doubtful affinities was captured in Ecua-
lA Geographical Historj^ of Mammals, p. 109.
LIFE OF TERTIARY PERIOD 259
dor. But in 1895 a larger species of the same genus was
obtained from Bogota; and it was then seen that they be-
longed to a group of which large numbers of fossil remains
had been found in the Santa Cruz beds. By a comparison
of these remains of various allied forms with the specimens
of those now living, it seems no longer possible to doubt that
marsupials of Australian type have existed in South America
in Middle or Late Tertiary times, and tiiat some of them
survive to-day in the equatorial Andes, where their small size
has probably saved them from extinction. Of these latter,
Mr. Lydekker says: "In the skeleton the lower jaw exhibits
the usual inflexion of the angle ; and the pelvis carries
marsupial bones. A small pouch is present in the female."
These small marsupials have been named Csenolestes, while
their fossil allies are so numerous and varied that they have
to be classed in three families — Abderitidae, Epanorthidse,
and Garzoniidae. This is only mentioned here to show the
large quantity of materials upon which these conclusions are
founded.
Teachings of Pleistocene Mammalia
For the purpose of the present work it is not necessary to
go into further details as to the development of the higher
forms of life, except to call attention to some other cases of
the sudden dying out of great numbers of the more developed
species or groups during the most recent geological period —
the Pleistocene.
It has already been shown how, in temperate South
America, the huge sloths and armadillos, the giant llamas,
the strange Toxodontia, and the early forms of horses all
disappeared at a comparatively recent epoch. In Xorth
America a similar phenomenon occurred. Two extinct lions;
a number of racoons and allied forms, including several ex-
tinct genera; six extinct species of horses; two tapirs; two
genera of peccaries ; a llama and a camel ; several extinct
bisons, sheep, and deer; two elephants and two mastodons,
260 THE WORLD OF LIFE
and four genera of tlie wonderful terrestrial slotlis, ranged
over the whole country as far north as Oregon and the Great
Lakes in quite recent times; while four genera of the great
ground-sloths have been found as far north as Pennsylvania.
This remarkable assemblage of large Mammalia at a period
so recent as to be coeval with that of man, is most extraor-
dinary; while that the whole series should have disappeared
before historical times is considered by most geologists to be
almost mysterious. At an earlier period, especially during
the Miocene (Middle Tertiary), Xorth America was also
wonderfully rich in Mammalia, including not only the ancestors
of existing types, but many now quite extinct. At this time
there were several kinds of monkevs allied to South American
forms; numerous extinct Carnivora, including the great sabre-
toothed tiger, Machserodus; several ancestral horses, includ-
ing the European Anchitherium ; several ancestral rhinoceroses,
the huge horned Brontotheriidae, the Oreodontidse, and many
ancestral swine. Almost all these became extinct at the end
of the Miocene age. "^
In Europe we find very similar phenomena. During the
Pleistocene age, the great Irish elk, the cave-lion and the
sabre-toothed tiger, cave-bears and hyaenas, rhinoceroses,
hippopotami and elephants, extinct species of deer, antelopes,
sheep and cattle, were abundant over a large part of Europe
(many even reaching our own country), and rapidly became
extinct; and what renders this more difficult to explain is,
that all of these and many others, with numerous ancestral
forms, had inhabited Europe throughout the Pliocene and
some even in Miocene times.
These very interesting changes in the northern hemisphere
are paralleled and completed in far-distant Australia. In
caves and surface deposits of recent formation a whole series
of fossil remains have been found, all of the marsupial order,
and most of them of extinct species and even extinct genera.
But what is more extraordinarv is, that several of them were
larger than any now living, while some were as gigantic as
LIFE OF TERTIARY PERIOD 201
the huge gi'ound-sloths and armadillos of the Pampas. There
were numerous kangaroos, some much lar<Ter than any liv-
ing, including species allied to the tree-kangaroos of New
Guinea; a Phascolomjs (wombat) as large as a donkey; the
Diprotodon, a thick-limbed animal nearly as large as an
elephant, but allied both to the kangaroos and the phalangor>.
Equally remarkable was the Tliylacoleo carnifex, nearly as
large as a lion and with remarkable teeth (Fig. 03, p. 258).
The very peculiar Xototherium, allied to the wombats, was
nearly as large as a rhinoceros; and several others imperfectly
known indicate that they were of larger size than their nearest
living allies.
A number of very similar facts are presented by recently
extinct birds. The Moas of ^ew Zealand were of various
sizes, but the largest was 8% feet high when standing natu-
rally, but when raising its body and neck to the fullest extent
it would have perhaps reached to a height of 12 feet.
In Madagascar also there was a huge bird, the ^pyornis,
which was probably larger than the largest of the Moas, and
whose egg, frequently found in sand-hills, sometimes measures
3 feet by 2% feet in circumference, and will hold more than
two gallons. It is almost certain that these huge birds were
all coeval with early man, and in the case of the Moas this
has been completely proved by finding their bones in ancient
native cooking ovens. It is probable, therefore, that their
final extinction was due to human agency.
Probable Cause of Extinction of the Pleistocejie Mammalia
The complete extinction of many of the largest Mammalia,
which were abundant in almost all parts of the world in
Pleistocene times, has not yet received a wholly satisfactory
explanation. The fact that the phenomenon is so near to
our own era renders it more striking than similar occurrences
in remote ages. With the one exception of the glacial e]><^ch,
there has been very little modification of tlie earth's surface
since the close of the Tertiary era ; and in several cases species
262 THE WORLD OF LIFE
which iindo"abtedly survived that event have since become ex-
tinct. This great climatic catastrophe did nndoubtedly pro-
duce extensive migration of Mammalia ; but, owing to the fact
that the ice-sheet had very definite limits, and that numbers
of large mammals were merely driven southward, it is not
held to be a sufficient cause for so general a destruction of the
larger forms of life.
Another circumstance that puts the glacial epoch out of
court as a sufficient explanation of the widespread extinction
is that in two very remote parts of the earth, both enjoying
a warm or even a sub-tropical climate — x\ustralia on the one
hand, and Brazil to Argentina on the other, — exactly the
same phenomena have occurred, and, so far as all the geo-
logical evidence shows, within the same general limits of time.
It is no doubt the case that at each of the dividing lines
of the Tertiary era — that is, in passing from the Eocene to
the Miocene, or from the latter to the Pliocene, and thence
to the Pleistocene — many large Mammalia have also become
extinct. But in these cases a much greater lapse of time can
be assumed, as well as larger changes in the physical condi-
tions, such as extension of land or water, climate, vegetation,
etc., which, combined with the special disabilities of very
large animals, are sufficient to account for the facts. It may
be well here to state again the causes which lead to the ex-
tinction of largo animals rather than small ones, as given
in my Darwinism (p. 394) more than twenty years ago, and
also in my Geographical Distribution of Animals, i. p. 157
(1876):
" In the first place, animals of great bulk require a proportionate
supply of food, and any adverse change of conditions would affect
them more seriously than it would affect smaller animals. In the
next place, the extreme specialisation of many of these large animals
would render it less easy for them to become modified in any new
direction required by the changed conditions. Still more impor-
tant, perhaps, is the fact that very large animals always increase
slowly as compared with small ones — the elephant producing a
LIFE OF TERTIARY PERIOD 203
single young one every three years, while a rahbit may have a litter
of seven or eight young two or three times a year. Now the prob-
ability of useful variations will be in direct proportion to the popu-
lation of the species, and, as the smaller animals are not only many
hundred times more numerous than the largest, but also increase
perhaps a hundred times as rapidly, they are able to become quickly
modified by variation and natural selection, while the large and
bulky species, being unable to vary quickly enough, are obliged to
succumb in the struggle for existence/^
To these reasons we may add that very large animals arc
less rapid in their motions, and thus less able to escape from
enemies or from many kinds of danger. The late Professor
O. Marsh, of Yale University, has well observed :
" In every vigorous primitive type which was destined to survive
many geological changes, there seems to have been a tendency to
throw off lateral branches, which became highly specialised, and
soon died out because they were unable to adapt themselves to new
conditions. . . . The whole narrow path of the Suilline (hog)
type, throughout the entire series of the American tertiaries, is
strewn w4th the remains of such ambitious offshoots, manv of them
attaining the size of a rhinoceros; while the typical pig, with an
obstinacy never lost, has held on in spite of catastrophes and evolu-
tion, and still lives in America to-day."
We may also remember that it is still more widely spread
over the Old World, under the various forms of the hojr-family
(Suidse), than it is in America, under the closely allied
peccary type (Dicotylida?).
That this is a true cause of the more frequent passing away
of the largest animal types in all geological epochs there can
be no doubt, but it certainly will not alone explain the dying
out of so many of the very largest ^Mammalia and birds dur-
ing a period of such limited duration as is the Pleistocene
(or Quaternary) age, and under conditions which were cer-
tainly not very different from those under whicli they had
been developed and had lived in many cases down to the
historical period.
264 THE WORLD OF LIFE
What we are seeking for is a cause which has been in
action over the whole earth during the period in question,
and which was adequate to produce the observed result.
AVhen the problem is stated in this way the answer is very
obvious. It is, moreover, a solution which has often been
suggested, though generally to be rejected as inadequate. It
has been so with myself, but why I can hardly say. In his
Antiquity of Man (4th ed., 1873, p. 418) Sir Charles Lyell
says:
^^ That the growing power of man may have lent its aid as the
destroying cause of many Pleistocene species must, however, be
granted; yet, before the introduction of fire-arms, or even the use
of improved weapons of stone, it seems more wonderful that the
aborigines were able to hold their own against the cave-lion, hyena,
and wild bull, and to cope with such enemies, than that they failed
to bring about their extinction.''
Looking at the whole subject again, with the much larger
bodv of facts at our command, I am convinced that the above
somewhat enigmatic passage really gives the clue to the whole
problem, and that the rapidity of the extinction of so many
large Mammalia is actually due to man's agency, acting in
co-operation with those general causes w^hich at the culmina-
tion of each geological era has led to the extinction of the
larger, the most specialised, or the most strangely modified
forms. The reason why this has not been seen to be a suffi-
cient explanation of the phenomena is, I think, due to two
circumstances. Even since the fact of the antiquity of man
w^as first accepted by European geologists only half a century
ago, each fresh discovery tending to extend that antiquity has
been met with the same incredulity and opposition as did
the first discovery of flint weapons by Boucher de Perthes
in the gTavels near Amiens. It has been thought necessary
to minimise each fresh item of evidence, or in many cases to re-
ject it altogether, on the plea of imperfect observation. Thus
the full weight of the ever-accumulating facts has never been
LIFE OF TERTIAKY TERIOD 265
adequately recognised, because each new writer has Weu afraid
to incur the stigma of credulity, and therefore usually limited
himself to such facts as he had himself observed, or could quote
from his best-known contemporaries. On the other hand, the
old idea that man was the latest product of nature (or of
evolution) still makes itself felt in the attempt to escape from
any evidence proving man's coexistence with such extinct
species as would imply greater antiquity. In the chapter on
The Antiquity of Man in l^orth America (in my Xatural
Selection and Tropical !N'ature) I have given numerous ex-
amples of both these states of mind. And what makes them
so specially unreasonable is, that all evolutionists are satis-
fied that the common ancestor of man and the anthropoid apes
must date back to the Miocene, if not to the Eocene period ;
so that the real mystery is, not that the works or the remains
of ancestral man are found throughout the Pleistocene period,
but that they are not also found throughout the Pliocene, and
also in some Miocene deposits. There is not, as often as-
sumed, one " missing link " to be discovered, but at least a
score such links, adequately to fill the gap between man and
apes ; and their non-discovery is now^ one of the strongest
proofs of the imperfection of the geological record.
When we find, as we do, that, with the one exception of
Australia, proofs of man's coexistence with all the great ex-
tinct Pleistocene Mammalia are sufiiciently clear, while that
the Australians are equally ancient is proved by their form-
ing so well-marked and unique a race, the fact that man should
every^vhere have helped to exterminate the various hugo
quadrupeds, whose flesh would be a highly valued food, al-
most becomes a certainty. The following passage from one
of our best authorities, Mr. R. Lydekker, F.K.S., puts the
w^hole case in a very clear light, though he does not definitely
accept the conclusion whicli I hold to be now well established.
He says:
" From the northern half of the Old World have disappeared the
mammoth, the elasmothere (a very peculiar, huge rhinoceros, whose
266 THE WORLD OP LIFE
skull was more than three feet long), the woolly and other rhino-
ceroses, the sabre-toothed tigers, etc.; North America has lost the
megalonyx and the Ohio mastodon; from South America, the
glyptodonts, mylodons, the megalothere, and the macrauchenia
have been swept away; while Australia no longer possesses the
diprotodon and various gigantic species of kangaroos and wombats.
In the northern hemisphere this impoverishment of the fauna has
been very generally attributed to the effects of the glacial period,
but, although this may have been a partial cause, it can hardly be
the only one. The mammoth, for instance, certainly lived during
a considerable portion of the glacial epoch, and if it survived thus
far, why should it disappear at the close? Moreover, all the Eu-
ropean mastodons and the southern elephant {Elephas meridionalis)
died out before the incoming of glacial conditions; and the same
is true of all the extinct elephants and mastodons of Southern
Asia. Further, a large number of English geologists believe the
brick earths of the Thames valley, which contain remains of rhino-
ceroses and elephants in abundance, to be of post-glacial age. As
regards the southern hemisphere, it can hardly be contended that
glacial conditions prevailed there at the same time as in the north-
ern half of the world.
" It is thus evident that, though a very great number of large
mammals were exterminated (perhaps partly by the aid of human
agency) at the close of the Pleistocene period, when the group had
attained its maximum development as regards the bodily size of its
members, yet other large forms had been steadily dying out in
previous epochs. And it would seem that there must be some
general, deep-seated cause affecting the life of a species with which
we are at present unacquainted. Indeed, as there is a term to the
life of an individual, what is more natural than that there should
also be one to the existence of a species. It still remains indeed,
to account for the fact that the larger Pleistocene mammals had
no successors in the greater part of the world, but perhaps, is in
some way connected with the advent of man." ^
It is sometimes thought that early man, with onlv the rudest
weapons, would be powerless against large and often well-
1 A Geographical History of Mammals, R. Lydekker, B.A., F.R.S., V.P.G.S.
etc., 1896, p. 18.
LIFE OF TEKTIAEY PERIOD 267
armed mammals. But this, I think, is quite a mistake. Xo
weapon is more effective for this purpose than a spear, of
various kinds, when large numbers of hunters attack a single
animal; and when made of tough wood, with the point hard-
ened by fire and well sharpened, it is as effective as when
metal heads are used. Bamboo, too, abundant in almost all
warm countries, forms a very deadly spear when cut obliquely
at the point. The way in which even a man-eating tiger is
killed by this means in Java is described in my ^lalay
Archipelago (p. 82). Such a method would doubtless have
been adopted even by Palaeolithic man, and would have been
effective against any of the larger animals of the Pleistocene
age.
It is therefore certain, that, so soon as man possessed
weapons and the use of fire, his power of intelligent com-
bination would have rendered him fully able to kill or cap-
ture any animal that has ever lived upon the earth ; and as
the flesh, bones, hair, horns, or skins would have been of
use to him, he would certainly have done so even had he
not the additional incentive that in many cases the animals
were destructive to his crops or dangerous to his children or
to himself. The numbers he would be able to destroy, es-
pecially of the young, would be an important factor in the
extermination of many of the larger species.
There remains, however, the question, well put by Mr.
Lydekker, whether there is not some general deep-seated cause
affecting the life of species, and sending to explain, if only
partially, the successive dying out of numbers of large ani-
mals involving a complete change in the preponderant typos
of organic life at certain epochs; and to this question and
some others allied to it a separate chapter must be devoted.
APPEXDIX
THE THEORY OF COXTINEXTAL EXTEXSIOXS
Most writers consider that the preceding facts (see p. 2-11) go to
prove the existence of a land-connection l)otwecn Soiitli America
268 THE WORLD OF LIFE
and Australia in Early or Middle Tertiary times. This, however,
seems to me to be highly improbable for reasons given at full in my
Island Life. Its supposed necessity depends on the assumption
that the geological record is fairly complete, even as regards these
small mammals, and that their not being yet discovered in the
northern continents proves that they never existed there. But the
extreme rarity of the small Secondary Mammalia, though they have
been found scattered over the whole northern hemisphere, and the
limited area in South America in which these Tertiary marsupials
have been found, taken in connection with the enormous areas of
geologically unexplored land in Asia and Australia, should make us
very cautious in assuming such vast and physically improbable
changes of land and sea at such a comparatively recent epoch.
The theory of land-connection also introduces enormous difficulties
of various kinds which it is well briefly to consider. If we suppose
an absolute land-connection in order to allow the marsupial type to
have entered Australia from temperate South America, we have
to face the incredible fact, that of the whole varied mammalian
fauna of the latter country this one group only was transmitted.
In these same deposits there are found ancestral hoofed animals of
small size (Pyrotherium) ; numerous rodents allied to cavies and
porcupines; a host of Edentata allied to sloths, ant-eaters, and
armadillos. These, taken altogether, are many times more numer-
ous than the marsupials; they were more varied in structure and
mode of life; and it is almost incredible that not one representa-
tive of these somewhat higher forms sliould have reached the new
country, or having reached it should have all died out, while the
inferior group alone survived. Then, again, we know that birds
and insects must have abounded in South America at the same
period, while the whole 7000 miles of connecting land must have
been well clothed with vegetation to support the varied life that
must have existed upon it during the period of immigration. Yet
no indication of a direct transference or interchange of these nu-
merous forms of life in any adequate amount is found in either
Australia or South Temperate America. We can hardly suppose
such an enormous extent of land to have been raised above the
ocean; that it should have become sufficiently stocked with life to
serve as a bridge (7000 miles long!), and that a few very small
marsupials only should have crossed it; that it then sank as rap-
LIFE OF TERTIARY PERIOD 261)
idly as it had been formed; with the one result of slocking Aus-
tralia with marsupials, while its other forms of life — plants, birds,
insects, molluscs — show an unmistakable derivation from the
Asiatic continent and islands. A careful examination ol' a large
globe or South Polar map, with a consideration of the diagram of
the proportionate height of land and depth of ocean at p. .315 of
my Darwinism, together with the argument founded upon it, will,
I think, convince my readers that difficulties in geographical dis-
tribution cannot be satisfactorily explained by such wildly im-
probable hypotheses. If the facts are carefully examined, it will
be found, as I have shown for the supposed " Atlantis " and
" Lemuria," that such hypothetical changes of sea and land always
create more serious difficulties than those which they are supposed
to explain. People never seem to consider what such an explana-
tion really means. They never follow out in imagination, step by
step, the formation of any such enormous connecting lands between
existing continents in accordance with what we know of the rate
of elevation and depression of land, and the corresponding organic
changes that must ensue. They seem to forget that such a vast
and complete change of position of sea and land is not really known
ever to have occurred.
Let us consider for a moment what the supposed land-connection
between South America and Australia really implies. The distance
is more than half as much again as the whole length of the South
American continent, and 1000 miles farther than from Southamj)-
ton to the Cape. This alone should surely give us pause. P)ut
unless we go as far south as the Antarctic circle, the depth of the
intervening ocean is about two miles; and until we get near Xew
Zealand there is not a single intervening island. There are here
none of the indications we expect to find of any geologically recent
depression of land on a vast scale. Of course we may suppose the
connection to have been along a great circle within ten degrees of
the South Pole, but that will not greatly shorten the distance,
while we have not a particle of evidence for such a vast ehange of
climate in Mid-Tertiary times as w(nild be required to render such
a route possible. But the mere physical dilhculties are equally
great. All land elevation or depression of which we have geo-
logical evidence has been exceedingly gradual, very limited in
extent, and always balanced by adjacent opposite movements. Such
270 THE WORLD OF LIFE
movements appear to be slow creeping undulations passing over
continental plateaus and their immediately adjacent submarine
extensions. Sometimes the depressions seem to have taken the
form of basins; but we cannot conceive of any elevation of conti-
nental dimensions, or depression of oceanic character as to depth
and area, without the complementary movement to complete the un-
dulation. A continental extension between South America and
Australia would almost necessarily imply a subsidence of one or
both of those countries over an equal area and to an equal depth;
and, so far as I am aware, no geological evidence has been ad-
duced of any such vast changes having occurred at so recent a
period in either continent. I believe it can now be truly said that
no stratigraphical geologist accepts the theory of frequent inter-
changes of continental and oceanic areas, which are so hastily
claimed by palaeontologists and biologists to be necessary in order
to overcome each apparent difficulty in the distribution of living
or extinct organisms, and this notwithstanding the number of such
difficulties which later discoveries have shown to be non-existent.
CHAPTER XIII
SOME EXTENSIONS OF DARWIn's THEORY
During the fifty years that have elapsed since the Darwinian
theory was first adequately, though not exhaustively, set fortli,
it has been subject to more than the usual amount of ob-
jection and misapprehension both by ignorant and learned
critics, by old-fashioned field-naturalists, and by the newer
schools of physiological specialists. Most of these objections
have been shown to be fallacious by some of the most eminent
students of evolution both here and on the Continent; but
a few still remain as stumbling-blocks to many earnest readers,
and, as they are continually adduced as being serious difii-
culties to the acceptance of natural selection as a sufficient ex-
planation of the origin of species, I propose to give a short
statement of what seem to me the three objections that most
require an answer at the present time. They are the follow-
ing:—
1. How can the beginnings of new organs be explained ?
2. How can the exact co-ordination of variations, needed
to produce any beneficial result, be effected with sufficient
rapidity and certainty ?
3. How is it that excessive developments of bulk, weapons,
ornaments, or colours, far beyond any utilitarian requirements,
have been so frequently produced ?
These three objections are of increasing degrees of impor-
tance. The first is, in my opinion, wholly speculative and
of no value, inasmuch as it applies to wliat happened in the
earlier stages of evolution, of which we have a mininium
of knowledge. The second is of somrwliat more importance:
for, though in the great majority of cases of adaptation the
ordinarv well-known facts of variation and survival would
271
272 THE WORLD OF LIFE
amply suffice, yet there are conceivable cases in wbich they
might be insufficient, and these cases are now explained by
a very interesting combination of the effects of acquired
modifications of the individual with the selection of congenital
variations. The third is, I think, somewhat more important,
as indicating a real deficiency in the theory, as originally
stated, but which is now well supplied by an extension of
that theory from the body itself to the reproductive germs
from which its parts are developed. I will, therefore, en-
deavour to explain in as simple a manner as possible how
these three objections have been overcome.
(1) The Beginnings of Organs
The objection that the first slight beginnings of new organs
would be useless, and that they could not be preserved and
increased by natural selection, was one of the most frequent
in the early stages of the discussion of the theory, and was
answered by Darwin himself in the later editions of his book.
But the objection still continues to be made, and owing to
the great mass of controversial literature continually issued
from the press many of the objectors do not see the replies
made to them ; there is therefore still room for a somewhat
more general answer, wdiich will apply not only to certain
individual cases, but to all. The most general and therefore
the best answ^er I have yet seen given is that of Professor
E. B. Poulton in his recently published Essays on Evolution.
He says:
" Organs are rarely formed anew in an animal, but they are
formed by the modification of pre-existing organs ; so that, instead
of having one beginning for each organ, we have to push the be-
ginning further and further back, and find that a single origin ac-
counts for several successive organs, or at any rate several functions,
instead of one."
He then goes on to show that the four limbs of vertebrates
have been again and again modified, for running, for climbing
to?
EXTEXSIOXS OF DARWINISM 273
for burrowing, for swimming, or for flying, and that their
first appearance goes back to PalaBozoic times in the paired
fins of early fishes, while their actual or'ujiii must have been
much further back, in creatures whose skeleton was not suffi-
ciently solidified to be preserved.
There is, however, a more general explanation even than
this, and one that applies to what has always been hehl to
be the most difiicult of all — that of the origin of the organs
of sense.
The various sensations by which w^e come into relation with
the external world — sight, hearing, smell, taste, and touch
■ — are really all specialisations of the last and most general,
that of material contact. We hear by means of a certain
range of air-waves acting on a specially constructed vibrating
organ ; we smell by the contact of excessively minute particles,
or actual molecules, given off by certain substances ; we taste
by the action of soluble matter in food on the papilke of the
tongue; and we see by the impact of ether-vibrations on the
retina; and as other ether-vibrations produce sensations of
cold or warmth, or, when in excess, acute pain, in every part
of the body, the modern view, that matter and ether are funda-
mentally connected if not identical, seems not unreasonable.
Xow, as all our organs of sense, however complex, are built
up from the protoplasm which constitutes the material of all
living organisms, and as all animals, however simple, exhibit
reactions which seem to imply that they have the rudiments
of most, if not all of our senses, we may conclude that just
in proportion as they have advanced in complexity of organi-
sation, so have special parts of their bodies become adapted
to receive, and their nervous system to respond to, tlio varinn?
contacts with the outer world which produce what wo terra
sensations. There is therefore, probably, no point in the
whole enormous length of the cliain of being, fnnn ourselves
back to the simple one-celled Amoeba, iu which the rudiments
of our five senses did not exist, although no separnto organs
may be detected. Just as its whole body sen'os alternately
274 THE WORLD OF LIFE
as outside or inside, as skin or as stomach, as limbs or as
lips, so may every part of it receive a slightly different sensa-
tion from a touch outside or a touch inside, from an air-
vibration or from an ether-vibration, from those emanations
which effect us as noxious odours or disgusting tastes. But
if this view is a sound one, as I think it will be admitted
that it is, how absurd is it to ask, " How did the eye or the
ear begin ? " They began in the potentiality of that marvel-
lous substance, protoplasm, and they were rendered possible
when that substance was endowed with the mysterious or-
ganising power we term life. First the cell was produced;
and, from the continued subdivision of the cell at each sub-
division taking a slightly different form and function, numer-
ous one-celled animals were formed; and a little later the
union of many cells of diverse forms and functions led to the
endless multicellular creatures, constituting the entire world of
life.
Thus every substance and every organ came into existence
when required by the organism imder the law of perpetual
variation and survival of the fittest, only limited by the
potentialities of living protoplasm. And if the higher sense-
organs were so produced, how much easier was the production
of such superficial appendages as horns and tusks, scales and
feathers, as they were required. Horns, for instance, are
either dermal or osseous outgrowths or a combination of both.
In the very earliest known vertebrates, the fishes of the
Silurian formation, we find the skin more or less covered with
tubercles, or plates, or spines. Here we have the rudiments
of all those dermal or osseous outgrowths which continue in
endless modifications through the countless ages that have
elapsed down to our own times. They appear and disappear,
as they are useful or useless, on various parts of the body,
as that body changes in form and in structure, and modifi-
cations of its external covering are needed. Hence the in-
finite variety in nature — a variety which, were it not so
familiar, would be beyond the wildest flights of imagination
EXTENSIONS OF DARWINISM 275
to suggest as possible developments from an apparently simple
protoplasmic cell. The idea, therefore, that there were, or
could be, at any successive periods, anything of the nature of
the abrupt beginning of completely new organs which had
nothing analogous in preceding generations is quite unsup-
ported by what is known of the progressive development of
all structures through slight modification of those which pre-
ceded them. The objection as to the heglmiings of new organs
is a purely imaginary one, wdiich entirely falls to pieces in
view of the wdiole known process of development from the
simplest cell (though in reality no cell is simple) to ever
higher and more complex aggregations of cells, till we come
to Mammalia and to man.
(2) The Co-ordination of Variations
The next difficulty, one which Herbert Spencer laid much
stress on, is, that every variation, to be of any use to a species,
requires a number of concurrent variations, often in dilTerent
parts of the body, and these, it is said, cannot be left to
chance. Herbert Spencer discussed this poi';t at great length
in his Factors of Organic Evolution ; and, as one of the illus-
trative cases, he takes the giraffe, w^hose enormously long neck
and fore-legs, he thinks, would have required so many con-
current variations that we cannot suppose them to have oc-
curred through ordinary variation. He therefore argues that
the inherited effects of use and disuse are the onlv causes
which could have brought it about; and Darwin himself ap-
pears to have thought that such inheritance did actually occur.
The points which Spencer mainly dwells upon are as fol-
lows : The increased length and massiveness of the neck
would require increased size and strength of the chest with
its bones and muscles to bear the additional weight, and also
great additions to the strength of the fore-legs to carry such
a burthen. Again, as the hind-legs have remained short, the
whole body is at a different angle from what it was before
the change from the ordinary antelope-type, and this would
276 THE WORLD OE LIFE
require a different shape in the articulating joints of the hips
and some change in the muscles; and this would be the more
important as the hind- and fore-legs now have unequal angular
motions when galloping, involving changed co-ordination in
all the connected parts, any failure in which would diminish
speed and thus be fatal to the varying individuals. Even
the blood-vessels and nerves of these various parts would re-
quire modifioations exactly adapted to the change in the other
parts ; and he urges that any individuals in Avhich all these
necessary variations did not take place simultaneously, would
be at a disadvantage and would not survive. To do his argu-
ment justice, I will quote one of his most forcible paragraphs.
" The immense change in the ratio of fore-quarters to hind-
quarters would make requisite a corresponding change of ratio in
the appliances carr3dng on the nutrition of the two. The entire
vascular system, arterial and venous, would have to undergo succes-
sive unbuildings and rebuildings to make its channels everywhere
adequate to the local requirements, since any want of adjustment
in the blood-supply to this or that set of muscles would entail in-
capacity, failure of speed, and loss of life. Moreover, the nerves
supplying the various sets of muscles would have to be appropriately
changed, as well as the central nervous tracts from which they
issued. Can we suppose that all these appropriate changes, too,
would be, step by step, simultaneously made by fortunate spon-
taneous variations occurring along with all the other fortunate
spontaneous variations? Considering how immense must be the
number of these required changes, added to the changes above
enumerated, the chances against any adequate readjustments for-
tuitously arising must be infinity to one."
Xow, this seems very forcible, and has, no doubt, con-
vinced many readers. Yet the argument is entirely fallacious,
because it is founded on the tacit assumption that the number
of the varying individuals is very small, and that the amount
of coincident variation is also both small and rare. It is
further founded on the assumption that the time allowed for
the production of any sufficient change to be of use is also
EXTEIsTSIONS OF DARWINISM 277
small. But I have shown in the early chapters of this book
(and much more fully in my Darwinism) that all these as-
sumptions are the very reverse of the known facts. The
numbers of varying individuals in any dominant species (and
it is only these which become modified into new species) is
to be counted by millions ; and as the whole number can, as
regards any needed modification, be divided into two lialves
— those which possess the special quality required above or
below the average — it may be said thali nearly half the total
number vary favourably, and about one-fourth of the whole
number in a very large degree. Again, it has been shown
that the number of coincident variations are very great, since
they are always present when only a dozen or twenty individ-
uals are compared; bnt nature deals with thousands and mil-
lions of individuals. Yet, again, we know that changes of the
environment are always very slow as measured by years or
generations, since not a single new species is known to have
come into existence during the whole of the Pleistocene period ;
and as fresh variations occur in every generation, almost any
character, with all its co-ordinated structures, would be con-
siderably modified in a hundred or a thousand generations, and
■we have no absolute knowledge that any great change would
be required in less time than this.^
lA very familiar fact will, I think, show that a large amount of co-
ordinated variability in different directions does actually occur. First-rate
bowlers and wicket-keepers, as well as first-rate batters, are not common in
proportion to the whole population of cricket-players. Each one of these
requires a special set of co-ordinated faculties — good eyesight, accurate
\ perception of distance and of time, with extremely rapid and accurate re-
sponse of all the muscles concerned in the operations each has to perform.
If all the special variations required to produce such individuals were sot
forth by a good physiologist in the detailed and forcible manner of the
passage quoted from Spencer about the giraffe, it would seem impossible
that good cricketers should ever arise from the average family types. Yat
they certainly do so arise. And just as cricketers are chosen, not by ex-
ternal characters, but by the results of actual work, so nature selects, not by
special characters or faculties, but by that combination of characters which
gives the greatest chance of survival in the complex, fluctuating environment
in which each creatures lives. The species thus lK»comes adapted, first to
278 THE WORLD OF LIFE
Objectors always forget that a dominant species has become
so because it is sufficiently adapted to its whole environment,
not only at any one time or to any average of conditions,
but to the most extreme adverse conditions Avhicli have oc-
curred during the thousands or millions of years of its exist-
ence as a species. This implies that, for all ordinary con-
ditions and all such adverse changes as occur but once in a
century of a millennium, the species has a surplus of adapt-
ability which allows it to keep up its immense population in
the midst of countless competitors and enemies. Examples
of such thoroughly well-adapted species were the American
bison and passenger pigeon, whose populations a century ago
were to be counted by millions and thousands of inillions,
which they w^ere fully able to maintain against all enemies
and competitors then in existence. But civilised man has so
modified and devastated the whole organic environment in a
single century as to bring about an extermination which the
slow changes of nature would almost certainly not have ef-
fected in a thousand or even a million of centuries. This
happened because the changes were different in kind, as well
as in rapidity, 'from any of nature's changes during the whole
period of the development of existing species.
But although I feel confident that the known amount of
variation would amply suffice for the adaptation of any domi-
nant species to a nomially changing environment, I admit that
there are conceivable cases in which changes may have been
so great and so comparatively rapid as to endanger the exist-
ence even of some of those species which had attained to a
dominant position; such, for instance, as the opening of a land
passage for very powerful new Carnivora into another con-
resist one danger, then another; first to one aspect of the ever-changing
environment, then to another; till during successive generations it becomes
so perfectly adapted to a long series of more or less injurious conditions,
that, under all ordinary conditions, it possesses a surplus of adaptation.
And as this complete adaptation is as often exhibited in colour and marking
as in structure, it is proved that the transmission of the effects of use and
disuse are not essential to the most complex adaptations.
EXTEXSIO.\S OF DAKWJMSM l>70
tinent or extensive area (as appears to have occurred with
Africa in Tertiary times), in ^vllicll case it is quite possible
that such an animal as the American bison mii^ht have been
first reduced in numbers, and, for want of any suflicieutly
rapid development of new means of protection, be ultimately
destroyed.
But a few years ago an idea occurred independently to three
biologists, of a self-acting jorinciple in nature which would be
of such assistance to any species in danger of extermination
as, in some cases at all events, would enable it to become
adapted to the new conditions. It would, in fact, increase the
powers of natural selection, as above explainc(l, to a degree
which might sometimes make all the difference between life
and death to a certain number of species. It depends upon
the w^ell-known fact that the use of any limb or organ strength-
ens or increases the growth of that part or organ. On this
fact depends all training for athletics or games; and it is
alleged by some trainers that any one, however weak naturally,
can have his strength very greatly increased by systematic
but carefully graded exercise. If, therefore, the survival of
any animal in presence of a new enemy or unaccustomed
danger depends upon increased powers of running, or jumping,
or tree-climbing, or swimming, then, during the process of
eliminating those individuals who were the worst in these re-
spects, all the remainder would have to exercise their powers
to the utmost, and would, in the act of doing so, increase
their power of escaping the danger. Thus a con-idrrable
number would become capable of surviving, year after year, to
a normal old age, and during this whole period would, year
by year, have fresh descendants, and of these only the very
best, the most gifted naturally, would survive. The in-
creased adaptation during the life of the individual would not
be transmitted, but the quality of being inijirovablc during life
would be transmitted, and thus additional tim*^ and a consider-
ablv increased ]K>])ulation would give more uuUcrials for
natural selection to act upon. With this help the species
280 THE WOKLD OF LIFE
might become so rapidly improved that the danger from the
new environment would be overcome, and a new type might
be produced which would continue to be a dominant one un-
der the new conditions.^
N^ow, while it must be admitted, that under certain con-
ditions, and with certain classes of adaptations, the normal
effects of natural selection would be facilitated by the aid of
individual adaptation through use of organs, yet its effect is
greatly limited by the fact that it will not apply to several
classes of adaptations which are quite unaffected by use or
exercise. Such are the colours of innumerable species, which
are in the highest degree adaptive, either as protecting them
from enemies, as a warning of hidden danger (stings, etc.),
as recognition-marks for young or for wanderers, or by mimi-
cry of protected groups. Here the tise is simply being seen
or not seen, neither of which can affect the colour of the
object. Again, nothing is more vitally important to many
animals than the form, size, and structure of the teeth, which
1 As many readers are ignorant of the extreme adaptability of many parts
of the body, not only during an individual life, but in a much shorter period,
I will here give an illustrative fact. A friend of mine was the resident
physician of a large county lunatic asylum. During his rounds one morning,
attended by one of his assistants and a warder, he stopped to converse with
a male patient who was only insane on one point and whose conversation
was very interesting. Suddenly the man sprang up and struck a violent
blow at the doctor's neck with a large sharpened nail, and almost com-
pletely severed the carotid artery. The warder seized the man, the assistant
gave the alarm, while my friend sat down and pressed his finger on the
proper spot to stop the violent flow of blood, which would otherwise have
quickly produced coma and death. Other doctors soon applied proper pres-
sure, and a competent surgeon was sent for, who, however, did not arrive
for more than an hour. The artery was then tied up and the patient got
to bed. He told me of this himself about two years afterwards, and, on
my inquiry how the functions of the great artery had been renewed, he
assured me that nothing but its permanent stoppage was possible, that
numerous small anastomosing branches enlarged under the pressure and
after a few months carried the whole current of blood that had before been
carried by the great artery, without any pain, and that at the time of speak-
ing he was quite as well as before the accident. Such a fact as this really
answers almost the whole of Herbert Spencer's argument which I have
quoted at p. 270.
EXTEXSIONS OF DARWl.XLSM i'8l
are wonderfully varied throughout the whole of th(^ VLricbrate
sub-kingdom. Yet the more or less use of the teeth cannot
be shown to have any tendency to change their fnnii or
structure in the special ways in which they have been again
and again changed, though it might possibly have induced
growth and increased size. Yet again, the scales or plates of
reptiles, the feathers of birds, and the hairy covering of mam-
mal?, have never been shown to have their special textures,
shape?, or density modified by the mere act of use. One
common error is that cold produces length and density of
hair, heat the reverse ; but the purely tropical monkey-tribe
are, as a rule, quite as well clothed with dense fur as most
of the temperate or arctic mammals, while no birds are more
luxuriantly feather-clad than those of the tropics. XeitlnT
is it certain that increased gazing improves the eyes, or loud
noises the ears, or increased eating the stomach ; so that we
must conclude that this aid to the powers of natural selection
is very partial in its action, and that it has no claim to the
important position sometimes given it.
(3) Germinal Seleclion, an Important Eximfiion of the
Theory of Natural Selection
Although I was at first inclined to accept Darwin's view of
the influence of female choice in determining the development
of ornamental colour or appendages in the males, yet, when
he had a(hhiced his wonderful array of facts bearing upon
the question in the Descent of Man, the evidence for any such
effective choice appeared so very scanty, and the ellects im-
puted to it so amazingly improbable, that T felt certain that
some other cause was at work. Tn my Tropical Nature
(1878) and in my Darwinism (1889) I treated the subject
at considerable length, adducing many facts to prove that, even
in birds, the colours and ornamental })lunies of the males were
not in themselves attractive, but served merely as signs of
sexual maturity and vigour. Tn the case of insects, especially
in butterflies, where the phenomena of colour, and to some
282 THE WOKLD OE LIEE
extent of ornament, are strikingly similar to those of birds,
the conception of a deliberate aesthetic choice, by the females,
of the details of colour marking, and shape of wings, seemed
almost unthinkable, and was supported by even less evidence
than in the case of birds.
After long consideration of the question in all its bearings,
and taking account of the various suggestions that had been
made by competent observers, I arrived at certain conclu-
sions which I stated as follows :
" The various causes of colour in the animal world are, molecular
and chemical change of the substance of their integuments, or the
action upon it of heat, light, or moisture. Colour is also produced
by the interference of light in superposed transparent lamellae or by
excessively fine surface striae. These elementary conditions for the
production of colour are found everywhere in the surface-structures
of animals, so that its presence must be looked upon as normal, its
absence exceptional.
" Colours are fixed or modified in animals by natural selection
for various purposes : obscure or imitative colours for concealment ;
gaudy colours as a warning; and special markings either for easy
recognition by strayed individuals or by young, or to divert attack
from a vital part, as in the large brilliantly marked wings of some
butterflies and moths.
" Colours are produced or intensified by processes of develop-
ment, either where the integument or its appendages undergo great
extension or change of form, or where there is a surplus of vital
energy, as in male animals generally, more especially at the breed-
ing season." ^
ISTow the idea here suggested, of all these strange and beau-
tiful developments of plumage, of ornaments, or of colour
being primarily due to surplus vitality and growth-power in
dominant species, and especially in the males, seems a fairly
adequate solution of the problem. For the individuals which
possessed it in the highest degree would survive longest, would
1 Natural Selection and Tropical Nature (new ed., 1895), pp. 391-392.
For full details see Darwinism, chap. x. (1901).
EXTENSIONS OF DARWINISM 283
have most offspring who were equally or even more hijrhly
gifted; and thus there would arise a continually increasing
vitality whicli would be partly expended in the further develop-
ment of those ornaments and plumes which are its result and
outward manifestation. The varvine^ conditions of existence
would determine the particular part of tlie body at which such
accessory ornaments miglit arise, usually^ no doubt, directed
by utility to the species. Thus the glorious train of the pea-
cock might have begim in mere density of plumage covering
a vital part and one specially subject to attack by birrls or
beasts of prey, and, once started, these plumes would continue
to increase in number and size, as being an outlet for vital
energy, till at last they became so enormously lengthened as
to become dangerous by their weight being a check to speed
in running or agility in taking flight. This is already the
case with the peacock, which has some difficulty in rising from
the ground and flies very heavily. Its enemies in India are
tigers and all the larger members of the cat-tribe, and when
any of these approach its feeding-grounds it takes alarm and
at once flies up to the low^er branches of large trees. In the
ArgTis-pheasant it is the secondary wing-featliers that are ex-
ceedingly long and broad, so as to be almost as much a liin-
drance to strong or rapid flight as is the train of the pea-
cock; and in both birds these ornamental plumes have evi-
dently reached the utmost dimensions compatible with the
safety of the species.
There can also be little doubt that in manv of the birds-
of-paradise and of the humming-birds, in the enormous crest
of the umbrella-bird, in the huge beaks of the hornbiils and
the toucans, in the lenc^thv neck and lec:s of the flaminc:os and
the herons, these various oraamental or usefid appen(iag(\>< liave
reached or even overpassed the maximum of utility. In an-
other class of animals we have the same phenomenon. The
expansion of the wings in butlerflies and motlis reaches a
maximum in several distinct families — the Papilionidre, the
Morphidffi, the Bond\vces, au'l the Xoctuje, in all <>f whirli it
2S4 THE WORLD OF LIFE
is sometimes from nine to ten inches. Here, again, we seem
to find a tendency to development in size, which has gone on
from age to age, till limits have been reached to exceed which
threatens the existence of the species.
The progressive development of many groups of animals
affords curious illustrations of this continuous increase in bulk,
or in the size of particular organs, till they have actually over-
passed the line of permanent safety, and under the first ad-
verse conditions have led to extinction. Both reptiles and
mammals originated in creatures of small size which gradually
increased in bulk, in certain types, till they suddenly became
exterminated. In the former class the increase was ap-
parently rapid, till the hugest land-animals that ever lived
appeared upon the earth — the Dinosauria of the Jurassic and
Cretaceous periods, already described. Many of them also de-
veloped strange horns and teeth; and these, too, when they
reached their maximum, also suddenly disappeared. Flying
reptiles — the Pterodactyles — also began as small animals
and continually increased, till those of the period of our Chalk
attained the greatest dimensions ever reached by a flying crea-
ture, and then the whole group became extinct at a time when
a higher type, the birds, w^ere rapidly developing.
With mammals the case is even more striking, all the ear-
liest forms of the Secondary age being quite small; while in
the Tertiary period they began to increase in size and to de-
velop into a great variety of types of structure ; till, in an
age just previous to our own, such exceedingly diverse groups
as the marsupials, the sloths, the elephants, the camels, and
the deer, all reached their maximum of size and variety of
strange forms, the most developed of which then became ex-
tinct. Others of a lower and more generalised type, but
equally bulky, had successively disappeared at the termina-
tion of each subdivision of the Tertiary age. It is here that
we can trace the specialisation and increase in size of the
horse-tribe and of the deer; tlie latter passing from a horn-
less state to one of simple horns, gradually increasing in size
Fig. 94. — MacJurrodus neogwus ( Sabre-Toothed Ti<,n'r).
From the Pleistocene of Buenos Ayres. One-eighth nat. size. (Nicholson's
Palaeontology.)
Fig. 95. — Skeleton of liiuiit Deer {Ccrrus <ii;i(iiilruft) . (li.M. (Juide.)
From a peat-bog in Ireland. One-thirtieth nat. size.
The antlers were often 9 feet across from tip to tip, sometimes 11 feet.
EXTENSIONS OF DARWINISM 285
and complexity of branching, till they culminated in tlic great
Irish elk, which was the contemporary of the mammoth and
man in our own country.
Dr. A. S. Woodward, keeper of Geology in the British
Museum, discussed this curious phcnumenou in his presi-
dential address to the Geological Section of the British Asso-
ciation in 1909 ; and a few extracts will show how widespread
are these facts, and the great interest they have excited.
After sketching out the whole course of animal development,
and showing how universal is the law (much empliasised by
Darwin), that the higher form of one group never developed
from similar forms of a preceding lower type, but that both
arose from an early, more generalised type, he says:
*' To have proved, for example, that flying reptiles did not pass
into birds or bats, that hoofed Dinosaurs did not change into
hoofed mammals, and that Ichthyosaurs did not become porpoises,
and to have shown that all these later animals were mere mimics
of their ^predecessors, originating independently from a higher yet
generalised stock, is a remarkable achievement."
Then comes a reference to the subject we are now discuss-
ing:
" Still more significant, howeve-r, is the discovery, that towards
the end of their career through geological time, totally difTerent
races of animals repeatedly exhibit certain peculiar features which
can only be described as infallible marks of old age. The growth
to a very large size is one of these marks, as we observe in the
giant Pterodactyls of the Cretaceous i^eriod, the colossal Dinosaurs
of the Upper Jurassic and Cretaceous, and the large mammals of
the Pleistocene and the present day. It is not, of course, all the
members of a race that increase in size; some remain small until
the end, and they generally survive long after the others are ex-
tinct.
"Another frequent mark of old age In races was first discussed
and clearly pointed out by Professor C. E. Beechor of Yale. It is
the tendency of all animals with skeletons to produce a superfluity
of dead matter, which accumulates in the form of spines or bosses
28G THE WOKLD OF LIFE
as soon as the race they represent has reached its prime and begins
to be on the down grade. Among famiUar instances may be men-
tioned the curiously spiny Graptolites at the end of the Silurian, the
horned Pariasaurians at the beginning of the Trias, the armour-
plated and horned Dinosaurs at the end of the Cretaceous, and the
cattle or deer of modern Tertiary times. . . . The growth of
these excrescences, both in relative size and complication, was con-
tinual and persistent until the climax was reached and the extreme
forms died out. ...
" It appears, indeed, that when some part of an animal (whether
an excrescence or a normal structure) began to grow relatively
large in successive generations during geological time, it often ac-
quired some mysterious impetus by which it continued to increase
long after it had reached the serviceable limit. The unwieldy
antlers of the extinct Sedgwick's deer and Irish deer (Fig. 95),
for example, must have been impediments rather than useful
weapons. Tlie excessive enlargement of the upper canine teeth in
the sabre-toothed tigers (Machaerodus and its allies) must also
eventually have hindered rather than aided the capture and eating
of prey.'' ^
Dr. Woodward further remarks:
" The curious gradual elongation of the face in the Oligocene
and Miocene Mastodons can only be regarded as another illustra-
tion of the same phenomenon. In successive generations of these
animals the limbs seem to have grown continually longer, while the
neck remained short, so that the head necessarily became more and
more elongated to crop the vegetation on the ground. A limit of
mechanical efficiency was eventually reached, and then there sur-
vived only those members of the group in which the attenuated
mandibles became shortened, leaving the modified face to act as a
1 The species Maclicerodus neogceus, the skull of which is shewn in Fig. 94,
appears lo have had the largest canines of any species of the genus; and we
are told by Messrs. Xicholson and Lydekker (Manual of Palaeontology^ ii. p.
1449) that the upper carnassial tooth (the fourth premolar) "has four
distinct lobes, and is thus the most complex example of this type of tooth
known." The canines were about 9 inches long (more than half the length
of the whole skull), and very massive in proportion. It became extinct in
South America in the Pleistocene period, about the same time as the last of
the European species.
exte^sio:n's of darwixism
28'
proboscis. Tlie elephants thus arose as a kind of aftertlioiiglit
from a group of quadrupeds that were rapidly approaching tlicir
doom." (See figures in last chapter, p. :^-")7.)
This last is a specially interesting case, because it is the
only^ one in which, without change of general environnifnt,
or apparently of habits, a highly developed animal has re-
traced its latest steps, and then advanced in a new line of de-
velopment, leading to the wonderful trunk and the cnurmous
tusks of the modern elephant, as explained in Chapter XIT.
That these have now attained the maximum of useful growth
is indicated bv the fact that amoni>: the extinct fonus are those
in which they are developed to an unwieldy size, as in Elephas
ganesa of Xorth-West India, whose slightly curved tusks, some-
times nearly 10 feet long, must have put an enormous strain
upon the neck, and the mammoth, whose greatly curved tusks
were almost equally heavy.
Excessive Development of Lower Animals before Extinction
My friend Professor Judd has called my attention to the
fact that many of the lower forms of life exhibited similar
phenomena. The Trilobites (primitive crustaceans) which
were extremely abundant in the Pala?ozoic rocks, in their last
Fig. 96. — Conocoryphc sultzcri.
Upper Cambrian.
Fio. 97. — Paradonides bohcmicus.
Upper Cambrian.
288
THE WORLD OF LIFE
stages " developed strange knobs and spikes on their shells, so
that thej seemed to be trying experiments in excessive vari-
ation.'^
Figs. 96, 97^ show typical forms of Trilobites (so called
from their three-lobed bodies) ; while at a later period, when
the whole group was approaching extinction, it produced
spined forms like that shown in Fig. 98.
Excentric forms of Ammonites
At a later period the wonderfully rich and varied Am-
monites show still more curious changes. Beginning in the
Devonian formation thev increased
in varietv of form and structure
all through the succeeding forma-
tions, till they finally died out in
the Cretaceous. The two species
here figured from the Trias (Figs.
99, 100) may be taken as typical;
but the variations in surface pat-
tern are almost infinite. Visitors
to Weymouth or Lyme Regis maj"
find such in abundance under Lias
cliffs, or in the former place
along the shores of the backwater.
As time went on Ammonites in-
FiG. ^^ — Acidaspis dufrenoyi. creased in maximum size, till in
Silurian (Bohemia).
the Chalk formation specimens 2
or 3 feet diameter are not uncommon. One of the largest
English specimens in the British Museiim (Xatural History)
was found at Rottingdean, near Brighton, and is 3 feet 8 inches
across; but the largest known is an allied species from the
Upper Chalk of Westphalia, and has the enormous diameter
of 6 feet 8 inches.
It is an interesting fact that the very earliest Ammonites
were straight, and gradually became closely coiled. This
form was maintained almost constant throu2:hout the vast
EXTENSIONS OF DARWINISM
289
periods of the Mesozoic age, till towards llie end, when the
whole race was about to die out, they seemed to try to go
back to their original form, which some almost reached (Fi^.
Fig. 99. — Ceratites nodosus.
Trias.
Fig. 100. — Trachyceras aon.
Trias.
105), while others, as Professor Judd remarks (in a letter),
" before finally disappearing, twisted and untwisted them-
selves, and as it were wriggled themselves into extraordinary
Fig. 101. — Crioceras emerici.
Cretaceous.
Fig. 102. — Ileteroceras cmcrici.
Cretaceous.
shapes, in the last throes of dissolution.'- These strange forms
(Figs. 90-106) are reproduced from Nicholson's PaUeontol-
ogy, and there are many others.
290
THE WOKLD OF LIFE
Fig. 103. — Macroscapliites ivanii.
Cretaceous. '
Fig. 104. — Hamites rotundus.
Cretaceous.
Fig. 105. — Ptychoceras emericianum.
Cretaceous.
Fig. lOG. — Ancyloceras Matheronianum.
Gault.
Late Ammonites. (From Nicholson's Palaeontology.)
Special Features in the Development of Vertehrates
Another remarkable fact dwelt upon in Dr. Woodward's
address is the remarkably small brains of those early types
of vertebrates which were not destined to survive. The most
EXTE:^rSIOXS of DARWIXISM 291
striking cases are those of the Mesozoic reptiles and the early
Tertiary ungulate mammals, which both increased to such an
enormous bulk, yet retained throughout an almost ludicrously
small brain, as described in the last chapter. The same was
the case to a somewhat less extent with the carnivorous mam-
mals, the Creodonta and Sparassodonta of the early Tertiaries
both of the eastern and western hemispheres. These were
sometimes as large as lions or bears, and had equally well de-
veloped canine teeth, but very small brains; and they all died
out in Eocene or early Miocene times, giving way to small an-
cestral forms of our modern carnivores, which then increased
in size and developed larger brains, culminating in the highly
intelligent fox and dog, cat and leopard, of our own day.
Yet another singular feature of some of the more highly
developed vertebrates is the partial or total loss of teeth. This
is well shown in the camels, which have only a pair uf in-
cisors in the upper jaw; while the whole vast family of the
deer, cattle, and sheep have a completely toothless pad in the
front of the upper jaws. This is apparently better adapted
for rapid browsing of grass and low herbage — whieli is stored
up in the 23aunch for rumination when at rest; and the ab-
sence of teeth as a defence is compensated by the possession
of horns in a great variety of form and structure.
Even more remarkable is the total loss of teeth bv modern
birds, although the early types of birds possessed them. The
bill, however, is often a very effective piercing or tearing
weapon ; and their strongly grasping claws and hooked bill
render the birds of prey almost as powerful and d instructive
as the smaller members of the cat-tribe. This partial or total
disappearance of the teeth has no doubt been helped on l)y the
same principle which led to the persistent increase of useless
appendages till checked by natural selection or till it led to
the extinction of the entire race.
292 THE WORLD OF LIFE
Germinal Selection
The numerous and varied phenomena which have been
merely sketched in outline in the present chapter receive an
approximate explanation by Professor Weismann's theory of
germinal selection, which he first published in 1896. He
appears to have been led to it by feeling the difficulty of ex-
plaining many of these phenomena by the ^' natural selection "
of Darwin; but to have laid more stress on those of Section 2
of the present chapter than those of Section 3. He had in
1892 published his elaborate volume on The Germ-Plasm a
Theory of Heredity, to which this later theory is a logical
sequel.
During the last quarter of a century many striking discov-
eries have been made in what may be termed the mechanism
of growth and reproduction ; each successive advance in micro-
scopic power and methods of observation have brought to light
whole worlds of complex structure and purposive transfor-
mations in w^hat was before looked upon as structureless cells
or corpuscles. Some attempt will be made in a later chapter
to discuss these primary life-phenomena; here it is only neces-
sary to show briefly how Weismann's new theory helps us to
understand the facts of life-development we have been dealing
with. For this purpose I cannot do better than quote Pro-
fessor Lloyd Morgan's very clear statement of the theory.
He says : ^
" The additional factor which Dr. Weismann suggests is what
he terms ^ germinal selection.' This, briefly stated, is as follows : —
There is a competition for nutriment among those parts of the germ
named determinants, from which the several organs or groups of
organs are developed. In this competition the stronger deter-
minants get the best of it, and are further developed at the expense
of the weaker determinants, which are starved, and tend to dwin-
dle and eventually disappear. The suggestion is interestingj but
one well-nigh impossible to test by observation. If accepted as a
1 Habit and Instinct, p. 310.
EXTEJN^SIO^^S OF DAKWINISM 293
factor, it would seiTe to account for the inordinate growth of cer-
tain structures, such as the exuberance of some secondary sexual
characters, and for the existence of determinate variations, that is
to say, variations along special or particular lines of adaptation."
It may be well to give here Weismann's own definition of
what he means by " determinants," as quoted by Professor J.
Arthur Thomson in his fine volume on Heredity (p. 435) :
" ' I assume,' Weismann says, ^ that the germ-plasm consists of
a large number of different parts, each of which stands in a definite
relation to particular cells or kinds of cells in the organism to be
developed — that is, tliey are * primary constituents' in the sense
that their co-operation in the production of a particular part of the
organism is indispensable, the part being determined both as to its
existence and its nature by the predestined particles of the germ-
plasm. I therefore call these Determinants, and the parts of the
complete organism which they determine Determinates," ^
Professor Thomson continues thus:
" But how many determinants are to be postulated in any given
case? "Weismann supposes that every independently variable and
independently heritable character is represented in the germ-plasm
by a determinant. A lock of white hair among the dark may re-
appear at the same place for several generations; it is difficult to
interpret such facts of particular inheritance except on the theory
that the germ -plasm is built up of a large number of different de-
terminants. It may be pointed out that almost all biologists who
have tried to form a conception of the ultimate structure of living
matter have been led to the assumption — expressed in very varied
phraseology — of ultimate protoplasmic units which have the power
of growth and division. It is in no way peculiar to Weismann to
imagine biophors and to credit them with the powers of growing
and dividing.''
I quote these passages because Professor Thomson is thor-
oughly acquainted, not only with all Weismann's work, having
himself translated some of them, but also with that of other
1 The Evolution Theory, 1004. vol. i. p. 355.
294 THE WOELD OF LIFE
European and American writers on this very difficult prob-
lem; and he arrives at the conclusion, that Weismann's theory
is the most carefully and logically worked out, and that some
such conception is essential for a comprehension of the won-
derfully complex phenomena of heredity. He also quite
agrees with the conception that as these vital elements of the
germ-plasm grow and multiply during the life of the organism,
they must be nourished by fluids derived from it, and that
there must be slight differences between them in size and
vigour, and a struggle for existence in which the most vigorous
survive. These more vigorous determinants will lead to more
vigorous growth of the special part or organ they determine —
hair, horns, ornaments, etc., — and wherever this increase is
useful, or even not hurtful, to the species, it will go on in-
creasing, generation after generation, by the survival of more
and more vigorous determinants.
There is therefore both an internal and an external strug-
gle for existence affecting all the special parts — organs, or-
naments, etc. — of ever}^ living thing. With regard to the
more important sti-uctures, such as the limbs, the organs of
vision and hearing, the teeth, stomach, heart, lungs, etc., on
Avhich the very existence of the individual as well as of the
species depends, survival of the fittest in due co-ordination
with all other parts of the body will continually check any
tendency to unbalanced development, and thus, generation by
generation, suppress the tendency of the more vigorous de-
terminants to increase the growth and vigour of its special
determinates, by elimination of the individuals which exhibit
such unbalanced gro^vth. But in the case of appendages, or-
naments, or brilliant colours, which may begin as a mere out-
let for superfluous vital energy in dominant races, and then
be selected and utilised for purposes of recognition, warning,
imitative concealment, or for combat among males, there w^ill
not be the same danger to the ver)^ existence of the adult ani-
mal. It will, however, often happen that the increase through
germinal selection Avill continue beyond the point of absolute
EXTENSlOiVS OF DxVK\VI.\i;SM 205
utility to tlie individual; between which and the jooint of ef-
fective hurtfulness there may be a considerable margin. In
this way w^e have a quite intelligible exi)lanation of the enor-
mous development of feathers or decorative pi Limes in so many
birds, enormous horns in deer and antelopes, huge tusks in
elephants, and huge canine teeth in other quadrupeds. Tliis
view is supported by the suggestive fact, that many of these
appendages are retained only for a short period, during the
breeding season, when vigour is greatest and food most abun-
dant, and when therefore they are least injurious.
Again, when acting in an opposite direction, the theory
serves to explain the rapid dwindling and final disappearance
of some useless organs, which mere disuse is hardly sufficient
to explain; such are the lost hind limbs of whales, llie rudi-
mentary wings of the Apteryx, the toothless beak of birds, ete.
In such cases, after natural selection had reduced the part to
a rudimental condition, any regrowth would be injurious, and
thus determinants of increased vigour would be suppressed
by the non-survival of the adult, leaving the weaker deter-
minants to be crowded out by the competition of those of ad-
jacent parts, the increased development of which was ad-
vantageous.
By this very ingenious, but, though speculative, highly
probable hypothesis, extending the s]:)hero of c<inipetition for
nourishment and survival of the fittest from \\\o nTgani>=m as
a whole to some of its elementarv vital units, Professor Weis-
mann has, I think, overcome the one real diHieulty in the in-
terpretation of the external forms of living things, in all their
marvellous details, in tenns of normal .variation and survival
of the fittest. We have here that '^ mysterious impetus " to
increase beyond the useful limit which Dr. Woodward has rt^
ferred to in his address already quoted, and which is also
a cause of the extinction of species to which Mr. Lydekker
referred us, as quoted towards the end of the preceding chap-
ter.
296 THE WORLD OF LIFE
Illustrative Cases of Extreme Development
Two examples of this extreme development have not, I
think, jet been noticed in this connection. The wonderful
long and perfectly straight spirally twisted tusk of the strange
Cetaceous mammal, the narw^hal, is formed by an extreme de-
velopment, in the male only, of one of a pair of teeth in the
upper jaw. All other teeth are rudimentary, as is the right
tooth of the pair of which the left forms the tusk, often 7
or 8 feet long, and formed of a very fine heavy ivory. The
use of this is completely unknown, for though two males have
been seen playing together, apparently, with their tusks, they
do not fight, and their food, being small Crustacea and other
Fig. 107. — Head of Babirusa {Bahirusa alfurus).
The tusks of this animal continue growing during life. Those of the upper jaw are
directed upward from the base so that they do not enter the mouth, but pierc-
ing the skin of the face, resemble horns rather than teeth, and curve backwards
and downwards. (Flower, Study of Mammals.)
marine animals, can have no relation to this weapon. We
may, however, suppose that the tusk was originally developed
as a defence against some enemy, when the narwhal itself was
smaller, and had a wider range beyond the Arctic seas which
it now inhabits; and when the enemv had become extinct this
strange weapon went on increasing through the law of germinal
selection, and has thus become useless to the existing animaL
EXTEiS^SIOXS OF DAEWIXISM 297
The other case is that of the equally remarkable Babinisa
of the islands of Celebes and Burn, in which the canines of
the males are so developed as to be useless for fighting- (see
Fig. 107). Here, too, there can be little doubt that the tusks
were originally of the same type as in the wild boar, and were
used for both attack and defence; but the ancestral form hav-
ing been long isolated in a country where there were no ene-
mies of importance, natural selection ceased to preser\'e thom
in their original useful form, and the initial curvature became
increased by germinal selection, while natural selection only
checked such developments as would be injurious to the in-
dividuals which exhibited them.
A Wider Application of the Principle of Germ-Selection
But it seems to me that the principle here suggested has a
still higher importance, inasmuch as it has been the normal
means of adding to and intensifying that endless varietv of
form, that strange luxuriance of outgrowths, and that ex-
quisite beauty of marking and brilliancy of colour, that ren-
der the world of life an inexpressible delight to all who have
been led to observe, to appreciate, or to study it. It is through
the action of some such internal selecting agency that we owe
much of what we must call the charming eccentricity of nature
— of those exuberances of growth which cause the nature-
lover to perpetually exclaim, " What can be the use of this ? '*
In the birds-of-paradise we had long known of the tail-
feathers, the breast-shields, the masses of plumage from under
the wings, the crests, the neck-tippets, all in wonderful variety
of shape and colour. Then, in the island of Batch iau 1 ob-
tained a bird in which from the bend of the wing (correspond-
ing to our wrist) there spring two slender and flexible white
feathers on each side standine; out from the wine: durinc: ilii^ht,
whence it has been termed the standard-winged bird-of-para-
dise. Again, a few years ago, there was discovered in the
mountains of German 'New Guinea another quite new type, in
which, from the corner of each eye, a long plume arises more
208 THE WORLD OF LIFE
than twice the length of the bird's body, and having, on one
side only of the midrib, a series of leaf-shaped thin horny
plates of a beautiful light-blue colour on the upper surface,
contrasting in a striking manner with the purple black, ochre
yellow, and rusty red of the rest of the plumage.
In the comparatively small number of birds-of -paradise
now known, we have a series of strange ornamental plumes
w^hich in their shape, their size, their colours, and their point
of origin on the bird, exhibit more varietv than is found in
any other family of birds, or perhaps in all other known birds ;
and we can now better explain this by the assistance of Weis-
mann's law in a highly dominant group inhabiting a region
which is strikin^'lv deficient in animals wdiich are inimical to
bird-life in a densely forest-clad country.
To this same principle we must, I think, impute that su-
perfluity of dazzling colour in many birds, but more especially
in many insects, in which it so often seems to go far beyond
usefulness for purposes of recognition, or as a warning, or a
distracting dazzle to an attacking enemy.
Even in the vegetable kingdom this same law may have
acted in the production of enoiTQOus masses of flowers or of
fruits, far beyond the needful purpose of perpetuating the
species ; and probably also of those examples of excessive bril-
liancy of colour, as in the intense blues of many gentians, the
vivid scarlet of the Cardinal lobelia, or the glistening yellow
of many of our buttercups. It is quite possible, therefore,
that to this principle of ^' germinal selection " we owe some
of the most exquisite refinements of beauty amid the endless
variety of form and colour both of the animal and the veg-
etable world.
We may also owe to it the superabundant production of sap
which enabled the early colonists of America to make almost
imlimited quantities of sugar from the '^ sugar maple."
Each tree will yield about four pounds of sugar yearly from
about thirty gallons of sap ; and it is stated by Lindley that a
tree wull yield this quantity for forty years without being at
EXTENSIONS OF DARWINISM 299
all injured; and large quantities of such sugar are still made
for home consumption, the molasses produced from ii l)oing
said to be superior in flavour to that from the sugar-cane.
Here surely is a verv renuirkable case of an excessive sur-
plus product which is of gTcat use to man, and, so far as
we can see, to man only. The same phenomenon of a sur-
plus product is presented by the Para rubber-trees (Sii)h«jnia,
many species), from which, at the pro]ier season, larttc quan-
tities of the precious sap can be withdrawn annually for very
long periods, without injuring the trees, or producing a dimi-
nution of the supply. There are also many other useful veg-
etable products, among those referred to in our fifteenth chaj)-
ter, to which the same remark will apply ; and it seems prrib-
able that we owe the whole of these, and many others not yet
discovered in the vast unexplored tropical forests, to this far-
reaching principle of " germinal selection.'^
General Conclusions as to Life-Development
Before quitting the subject of the course of development of
the entire world of life as shown by the geological record, to
which the present chapter is in a measure supplementary, it
will be w^ell to say something as to its broader features from
the point of view adopted in this work. This is, that beyond
all the phenomena of nature and their immediate causes and
laws there is Mind and Purpose; and that the ultimate pur-
pose is (so far as we can discern) the development of mankind
for an enduring spiritual existence. With this object in view-
it would be important to supply all possible aids that a ma-
terial world can give for the training and education of man's
higlier intellectual, moral, and aesthetic nature. If this view
is the true one, we may look upon our Universe, in all its parts
and durinc; its whole existence, as slowlv ]>ut surelv marchiui::
onwards to a predestined end ; and this involves the further
conception, that now that man /m.s^ boon dovolojiod, tliat lio is
in full possession of this earth, and that upon his proper use
of it his adequate preparation for the future life depends, then
300 THE WORLD OF LIFE
a great responsibility is placed upon him for the way in which
he deals with this his great heritage from all the ages, not only
as regards himself and his fellows of the present generation,
but towards the unknown multitude of future generations that
are to succeed him.
x\ll of us who are led to believe that there must be a being
or beings high and powerful enough to have been the real
cause of the material cosmos with its products life and mind,
can hardly escape from the old and much-derided view, that
this world of ours is the best of all possible worlds calculated
to bring about this result. And if the best for its special pur-
pose, then the whole course of life-development was the best;
then also every step in that development and every outcome
of it which we find in the living things which are our con-
temporaries are also the best — are here for a purpose in some
way connected with us; and if in our blind ignorance or
prejudice we destroy them before we have earnestly endeav-
oured to learn the lesson thev are intended to teach us, w^e
and our successors will be the losers — morally, intellectually,
and perhaps even physically.
Already in the progress of this work I have dwelt upon the
marvellous variety of the useful or beautiful products of the
vegetable and animal kingdoms far beyond their o^^TL uses, as
indicating a development for the ser^uce of man. This variety
and beauty, even the strangeness, the ugliness, and the unex-
pectedness we find everywhere in nature, are, and therefore
were intended to be, an important factor in our mental de-
velopment ; for they excite in us admiration, wonder, and
curiosity — the three emotions which stimulate first our at-
tention, then our determination to learn the how and the why,
which are the basis of observation and experiment and there-
fore of all science and all philosophy. These considerations
should lead us to look upon all the works of nature, animate or
inanimate, as invested with a certain sanctity, to be used by
us but not abused, and never to be recklessly destroyed or de-
faced. To pollute a spring or a river, to exterminate a bird
EXTENSIONS OF DARWINISM 301
or beast, should be treated as moral offences and as social
crimes; while all who profess religion or sincerely believe in
the Deity — the designer and maker of this world and of every
living thing — should, one would have thought, have placed
this among the first of their forbidden sins, since to deface
or destroy that which has been brought into existence for the
use and enjoyment, the education and elevation of the human
race, is a direct denial of the wisdom and goodness of the
Creator, about which thej so loudly and persistently prate and
preach.
Yet during the past century, which has seen those great ad-
vances in the Tcnowledge of Nature of which we are so proud,
there has been no corresponding development of a love or rev-
erence for her works ; so that never before has there been such
widespread ravage of the earth's surface by destruction of
native vegetation and with it of much animal life, and such
wholesale defacement of the earth by mineral workings and
by pouring into our streams and rivers the refuse of manufac-
tories and of cities; and this has been done by all the greatest
nations claiming the first place for civilisation and religion !
And what is Avorse, the greater part of this waste and devas-
tation has been and is being carried on, not for any good or
worthy purpose, but in the interest of personal greed and
avarice; so that in every case, while wealth has increased in
the hands of the few, millions are still living without the bare
necessaries for a healthy or a decent life, thousands dying
yearly of actual starvation, and other thousands being slowly
or suddenly destroyed by hideous diseases or accidents, directly
caused in this cruel race for wealth, and in ahuost everv case
easily preventable. Yet they are not ])revented, solely be-
cause to do so would somewhat diminish th(^ })rofits of the
capitalists and legislators who are directly responsible for this
almost world-wide defacement and destruction, and virtual
massacre of the ignorant and defenceless workers.
The nineteenth century saw the rise, the development, and
the culmination of these crimes against God and man. Let
302 THE WORLD OF LIFE
us hope that the twentieth century will see the rise of a truer
religion, a purer Christianity; that the conscience of our
rulers will no longer permit a single man, woman, or child to
have its life shortened or destroyed by any preventable cause,
however profitable the present system may be to their employ-
ers; that no one shall be allowed to accumulate wealth by the
labour of others unless and until every labourer shall have re-
ceived sufficient, not only for a bare subsistence, but for all the
reasonable comforts and enjoyments of life, including ample
recreation and provision for a restful and happy old age.
Briefly, the support of the labourers without any injury to
health or shortening of life should be a first charge upon the
products of labour. Every kind of labour that will not bear
this charge is immoral and is unworthy of a civilised com-
munity.
The Teaching of the Geological Record
But this is a digression. Let us now return to a consid-
eration of the main features of the course of life-development.
The first point to w^hich our attention may be directed is,
that the necessary dependence of animal life upon vegetation
is the cause of some of the most prominent and perhaps the
most puzzling features of the early life-world as presented to
us by the geological record. In the Palaeozoic age we already
meet with a very abundant and very varied aquatic life, in
which all the great classes of the animal kingdom — sponges,
zoophytes, echinoderms, worms, Mollusca, and vertebrates —
were already fully differentiated from each other as we now
find them, and existed in considerable variety and in gi'eat
numbers. It is quite possible that the seas and oceans of those
remote ages were nearly as full of life as they are now, though
the forms of life were less varied and generally of a lower type.
But, at the same time, the animal life of the land was very
scanty, the only vertebrates that occupied it being a few Am-
phibia and archaic reptiles. There were, however, a consid-
erable number of primitive centipedes, spiders, Crustacea, and
EXTENSIONS OF DARWINISM ;J03
even true insects, the latter having already become specialised
into several of our existing orders. All these occur either in
the Coal formation of Europe or the Devonian rocks of North
America, which seems to imply that when land-vegetation first
began to cover the earth a very long period elapsed before any
correspondingly abundant animal life was develo])ed ; and this
W'as what we, should expect, because it would be necessary for
the former to become thoroughly established and developed
into a sufficient variety of forms well adapted to all the dif-
ferent conditions of soil and climate, in order that they might
be able to resist the attacks of the larger plant-feeding animals,
as well as the myriads of insects when these appeared. So
far as we can judge, the vegetable kingdom was left to develop
freely during the enormous series of ages comprised in the
Devonian, Carboniferous, and Permian formations, to which
we must add the gap between the latter and the Triassic — the
first of the Secondary formations. By that time the whole
earth had probably become more or less forest-clad, but with
vegetation of a Ioav type mostly allied to our ferns and horse-
tails, with some of the earliest ancestral forms of pines and
cycads.
In the succeeding Secondary era the same general type of
vegetation prevailed till near its close ; but it was then every-
where subject to the attacks of large plant-devouring reptiles,
and under this new environment it must necessarilv have
started on new lines of evolution tending towards those higher
flowering plants which, throughout the Tertiary period, be-
came the dominant type of vegetation. It seems probable that
throughout the ages animal and vegetable life acted and re-
acted on each other. The earliest luxuriant land-vegetation,
that which formed the great coal-fields of the earth, was
probably adapted to the physical environment alone, almost
uninfluenced by the scanty animal life. Then reptiles and
mammals were differentiated ; but the former increased more
rapidly, being perhaps better fitted to live upon the early vege-
tation and to survive in the heavy carbonated atmosphere. This
304 THE WORLD OF LIFE
in turn became more varied and better adapted to resist their
attacks; and when the new type had become well established it
quickly replaced the earlier forms ; and the highly specialised
reptiles, unable to obtain sufficient nourishment from it, and
being also subject to the attacks of Camivora of increasing
power, and perhaps to some adverse climatic changes, quickly
disappeared. Then came the turn of the Mammalia, the birds,
and the more specialised insects, which, during this vast period,
had been slowly developing into varied but always rather
diminutive forms, the birds and mammals feeding probably
on insects, roots, and seeds; but, in proportion as the reptiles
disappeared, they were ready to branch out in various direc-
tions, occupying the many places in nature left vacant by these
animals, and thus initiated that wonderfully varied mam-
malian life which throughout the whole Tertiary period occu-
pied the earth's surface as completely, and almost as exclu-
sively, as the reptiles had done during the middle ages of geo-
logical time.
The reactions of insects and flowers are universally ad-
mitted, as are those between birds and fruits ; but the broader
aspect of this reaction between animal and plant life as a
whole has not, I think, received much attention. It does,
however, seem to throw a glimmer of light on the very puz-
zling facts of the vast development of Secondary reptilian
life, the apparent arrest of development of mammals during
the whole vast period, and the rapid and abundant outgrowths
of the higher types both of plants and of Mammalia in the
Tertiary age.
The complete metamorphosis, broadly speaking, of both
plant and animal life, on passing from the former to the lat-
ter epoch, is most startling. Such a change was, however, ab-
solutely essential, not only for the production of the higher
Mammalia and intellectual man, but also to provide for the
infinitely varied needs of man's material, moral, and aesthetic
development. The immensely varied plant-group of phanero-
gams has served to unlock for his service the myriad potenti-
EXTENSIONS OF DARWINISM 305
alities which lay hidden in protoplasm — the mysterious
physical basis of all life. To this vast series of herbs and
shrubs and forest-trees he owes most of the charms, the deli-
cacies, and the refinements of his existence — almost all his
fruits, most of his scents and savours, together with a large
part of the delight he experiences in mountain and valley,
forest, copse, and flower-spangled meadow, whieli everywhere
adorn his earthly dwelling-place.
To this we must add the infinitely varied uses to man of
domestic animals, all supplied by the higher Mammalia or
birds, while no single reptile has ever occupied or seems able
to occupy the same place. We can only speculate on the part
these have played in man's full development, but it must have
been a great and an important one. The caring for cattle and
sheep, the use of milk, butter, and cheese, and the weaving
of wool and preparation of leather, must have all tended to
raise him from the status of a beast of prey to that of the
civilised being to whom some animals at all events became
helpers and friends. And this elevation was carried a step
further when the horse and the dog became the companions
of his daily life, while fowls, pigeons, and various singing-
birds added new pleasures and occupations to his home. That
such creatures should have been slowly evolved so as to reach
their full development at the very time when lie became able
to profit by them must surely be accepted as additional evi-
dence of a foreseeing mind which, from the first dawn of life
in the vegetable and animal cells, so directed and organised
that life, in all its myriad forms, as, in the far-off future, to
provide all that was most essential for the growth and develop-
ment of man's spiritual nature.
In furtherance of this subject it would be necessary to put
a definite bar to the persistence of a lower type which might
have prevented or seriously checked the development of the
higher forms destined to succeed them ; and this seems to have
been done in the case of the ]^^esozoic reptiles by endowing
them with such a limited amount of intelligent vitalitv as
306 THE WORLD OF LIFE
would not lead to its automatic increase under the stress of a
long course of development, though accompanied by continual
change of conditions and enormous increase in size. Hence
the " ridiculously small brains " (as they have been termed)
of these huge and varied animals. We may learn from this
phenomenon, and the parallel case of the huge Dinocerata
among the Tertiary mammals, that development of a varied
form and structure through the struggle for existence does not
necessarily lead to an increase in intelligence or in the size and
complexity of its organ the brain, as has been generally as-
sumed to be the case.
If, as John Hunter, T. H. Huxley, and other eminent
thinkers have declared, '' life is the cause, not the consequence,
of organisation,'' so we may believe that mind is the cause,
not the consequence, of brain development. The first implies
that there is a cause of life independent of the organism
through which it is manifested, and this cause must itself be
persistent — eternal — life, any other supposition being es-
sentially unthinkable. And if we must posit an eternal Life
as the cause of life, we must equally posit an eternal Mind as
the cause of mind. And once accept this as the irreducible
minimum of a rational belief on these two great questions,
then the whole of the argument in this volume falls into logical
sequence.
Life as a cause of organisation is as clearly manifested
and as much a necessity in the plant as in the animal; but
they are plainly different kinds (or degrees) of life. So
there are undoubtedly different degrees and probably also dif-
ferent kinds of mind in various grades of animal life. And
as the life-giver must be supposed to cause the due amount
and kind of life to flow or be dra^vn into each organism, from
the universe of life in which it lives, so the mind-giver, in like
manner, enables each class or order of animals to obtain the
amount of mind requisite for its place in nature, and to or-
ganise a brain such as is required for the manifestation of that
limited amount of mind and no more.
EXTEIsrSIO:N^S OF DARWINISM 307
Thus and thus only, as it seems to mo, can we under-
stand the raison d' etre of these small-brained animals. They
were outgi'owths of the great tree of life for a temporary pur-
pose, to keep doA\Ti the coarser vegetation, to supply animal
food for the larger Carnivora, and thus give time for higher
forms to obtain a secure foothold and a sullicient amount of
varied form and structure, from which they could, when bet-
ter conditions prevailed, at once start on those wonderful di-
verging lines of advance which have resulted in the perfected
and glorious life-world in the midst of which we live, or ought
to live.
This view of the purport, the meaning, and the higher func-
tion of the gTcat and varied life-world brings us by a differ-
ent route to what many of our better thinkers and teachers
have tried to impress upon us — • that our great cities are the
" wens,'' the disease-products of humanity, and that until they
are abolished there can be no approach to a true or rational
civilisation.
This was the teaching of that true and far-seeing child of
nature, William Cobbett; it is the teaching of all our greatest
sanitarians ; it is the teaching of Nature herself in the com-
parative rural and urban death-rates. Yet we have no legis-
lator, no minister, who will determinedly set himself to put
an end to the continued growth of these " wens " ; which are
wholly and absolutely evil. I will, therefore, take this oppor-
tunity of showing how it can be done.
There is much talk now of what will and must be the
growth of London during the next twenty or fifty years ; and
of the necessity of bringing water from Wales to su})])ly the
increased pojjulation. But where is the necessity ? Why pro-
vide for a population which need never have existed, and
whose coming into existence will be an evil and of no pos-
sible use to any human beings but the landowners and specu-
lators, who will make money by the certain injury of their
fellow-citizens. If the House of Commons and the l>ondt»n
County Council are not the bond-slaves of the landowners and
308 THE WOELD OF LIFE
speculators, they have only to refuse to allow any further
water-supply to be provided for London except what now ex-
ists, and London will cease to grow. Let every speculator have
to provide water for and on his own estate, and the thing will
be done — to the enormous benefit of humanity.
The same thing can, I presume, be done by Parliament for
any other growing town or city. It can justly say : '^ When
you have not a gallon of polluted water in your town, and
when its death-rate is brought down to the average standard
of rural areas, we will reconsider the question of your further
growth.'' By that time, probably, there will be no public de-
mand for enlarging our " wens '' and a very strong and stem,
one for their cure or their abolition.
/
CHAPTER XIV
BIRDS AND INSECTS : AS PROOFS OF AN OKGANISING AND
DIRECTIVE LIFE-PRINCIPLE
If we strip a bird of its feathers so that we can see its bodj-
structure as it really is, it appears as the most ungainly and
misshapen of living creatures ; yet there is hardly a bird but
in its natural garment is pleasing in its form and motions,
while a large majority are among the most beautiful in shape
and proportions, the most graceful in their activities, and often
the most exquisite and fascinating of all the higher animals.
The fact is, that the feathers are not merely a surface-clothing
for the body and limbs, as is the hairy covering of most mam-
mals, but in the wing and tail-feathers form an essential part
of the structure of each species, without which it is not a com-
plete individual, and could hardly maintain its existence for
a single day. The whole internal structure has been gradually
built up in strict relation to this covering, so that every part
of the skeleton, every muscle, and the whole of the vascular
system for blood-circulation and aeration have been slowly
modified in such close adaptation to the whole of the plumage
that a bird without its feathers is almost as helpless as a mam-
mal which has lost its limbs, tail, and teeth.
Although birds are so highly organised as to rival mam-
' mals in intelligence, while they surpass them in activity and
in their high body -temperature, yet they owe this position to
an extreme retrogressive specialisation resulting in the com-
plete loss of the teeth, while the digits of the fore limb are re-
duced to three, the bones of which are more or less united, and,
though slightly movable, are almost entirely hidden under tho
skin.
The earliest fossil bird, the Arch^eopteryx, bad throe ap-
301)
310 THE WORLD OE LIFE
parentlj free and movable digits on the fore limbs, each end-
ing in a distinct claw ; while the two bones forming the fore-
arm appear to have been also free and movable, so that the
wing must have been much less compact and less effective for
flight than in modern birds. This bird was about as large as
a rook, but with a tail of twenty vertebra', each about half an
inch long and bearing a pair of feathers, each four inches in
length and half an inch broad, while the wing feathers were
nearly twice as long. The almost complete disappearance of
the unwieldy tail, with the fusing together of the wing-bones,
must have gone on continuously from that epoch. In the
Cretaceous period the long tail has disappeared, and the wing-
bones are much more like those of living birds; but the jaws
are still toothed. In the early Tertiary deposits bird-remains
are more numerous, and some of the chief orders of modern
birds seem to have existed, while a little later modern families
and genera appear.
The important point for our consideration here is that, in
the very earliest of the birds yet discovered which still re-
tained several reptilian characteristics, true feathers, both of
wings and tail, are so clearly shown as to leave no doubt of
their practical identity with those of living birds.
It is therefore evident that birds with feathers began to be
developed as early as (perhaps even earlier than) the mem-
branous-winged reptiles (Pterodactyles), and that these two
groups of flying vertebrates began on two opposite principles.
The birds must have started on the principle of condensation
and specialisation of the fore limb exclusively for flight by
means of feathers ; the other by the extension of one reptilian
digit to support a wing-membrane, while reserving the others
probably for suspension, as in the case of the thumb of the
bats.
The Marvel and Mystery of Feathers
Looking at it as a whole, the bird's wing seems to me
to be, of all the mere mechanical organs of any living thing,
PKOOIS OJ^^ OKGANiSi^'G Aili\D 311
that ^vhicli most clearly implies the working out of a j^recon-
ceived design in a new and apparently most complex and dilli-
cult manner, yet so as to produce a marvellously successful re-
sult. The idea worked out was to reduce the jointed bony
framework of the wings to a compact minimum of size and
maximum of strength in proportion to the muscular power
employed ; to enlarge the breastbone so as to give room for
greatly increased power of pectoral muscles; and to construct
that part of the wing used in flight in sucli a manner as to
combine great strength with extreme lightness and the most
perfect flexibility. In order to produce this more perfect in-
strument for flight the plan of a continuous membrane, as in
the flying reptiles (whose origin was probably contcm})ora-
neous with that of the earliest birds) and flying mammals, to
be developed at a much later period, was rejected, and its placo
was taken by a series of broad overlapping oars or vanes,
formed by a central rib of extreme strength, elasticity, and
lightness, with a web on each side made up of myriads of parts
or outgrowth so wonderfully attached and interlocked as to
form a self-supporting, highly elastic structure of almost in-
conceivable delicacy, very easily pierced or ruptured by the
impact of solid substances, yet able to sustain almost any
amount of air-pressure without injury. And even when any
part of this delicate web is injured by separating the adjacent
barbs from each other, they are so wonderfully constructed that
the pressure and movement of other feathers over them causes
them to unite together as firmly as before ; and this is done
not by any process of gro^vth, or by any adhesive exudation,
but by the mechanical structure of the delicate hooked lamelhn
of which they are composed.
The two illustrations here given (Figs. lOS, lOD) show two
of the adjacent fibre-like parts (barbs) of which the web of a
bird's feather is composed, and which are most clearly shown
in the wing-feathers. Tlie slender barbs or ribs of which the
web of the feather is made up can be best understood by strip-
ping off a portion of the wel) and separating two of the barbs
312
THE WOELD OE LIEE
from the rest. With a good lens the structure of the barbs,
with their delicate hooked barbules interlocking with the bent-
out upper margins of the barbules beneath them, can be seen,
as shown in the view and section here given. The barbs (B,
Magnified View of the Barbs and Barbules forming the Web of a Bird's
Wing-Feathers (X 50).
Fig. 108. — 'View of a portion of two adjacent Barbs (B, B), looking from
the Shaft towards the edge of the Feather.
bd, distal barbules; bp, proximal barbules.
Fig. 109. — Oblique Section through the Proximal Barbules in a plane par-
allel to the Distal Barbules of the upper Figure.
Letters as above ; 1, 2, 3, barbicels and hamuli of the ventral side of the distal
barbule; 4, barbicels of the dorsal side of the same, without hamuli.
(From Newton's Dictionary of Birds.)
B in the figures) are elastic, homj plates set close together on
each side of the midrib of the feather, and pointing obliquely
outwards; while the barbules are to the barbs what the barbs
are to the feather — excessively delicate horny plates, which
PKOors OF oega:xising mind 313
also grow obliquely outwards towards the tip of the barb.
Laterally they touch each other with smooth, glossy surfaces,
which are almost air-tight, yet allow whatever slight motions
that may be required during use, while remaining interlocked
with the barbules of the adjoining barb in the manner just de-
scribed. They are the essential elements of the feather, on which
its value both for flight and as a protective clothing depends.
Even in the smallest wing- feathers they are probably a liundred
thousand in number, since in the long wing-feather of a crane
the number is stated by Dr. Hans Gadow to be more than a
million.
What are termed the " contour-feathers " are those that
clothe the whole body and limbs of a bird with a garment of
extreme lightness which is almost comj^letely impen-ious to
either cold or heat. These feathers vary greatly in shape on
different parts of the body, sometimes forming a dense velvety
covering, as on the head and neck of many species, or de-
veloped into endless variety of ornament. They fit and overlap
each other so perfectly, and entangle so much air between
them, that rarely do birds suffer from cold, except when un-
able to obtain any shelter from violent storms or blizzards. Yet,
as everv sino'le feather is movable and erectile, the whole bodv
can be freely exposed to the air in times of oppressive heat, or
to dry the feathers rapidly after bathing or after unusually
heavy rain.
A great deal has been written on the mechanics of a bird's
flight, as dependent on the form and curvature of the feathers
and of the entire wing, the powerful muscular arrangements,
and especially the perfection of the adjustment by which dur-
ing the rapid do^vn-stroke the combined feathers constitute a
perfectly air-tight, exceedingly strong, yet highly elastic in-
strument for flight ; while the moment the upward motion be-
gins the feathers all turn upon their axes so that the air passes
between them with hardly any resistance, and when they again
begin the down-stroke close up nutomatically as air-tight as
before. Thus the effective down-strokes follow each other so
314 THE WOKLD OE LIFE
rapidly that, together with the support given by the hinder
portion of the wings and tail, the onward motion is kept up,
and the strongest flying birds exhibit hardly any undulation in
the course they are pursuing. But very little is said about the
minute structure of the feathers themselves, which are what
renders perfect flight in almost every change of conditions a
possibility and an actually achieved result.
But there is a further difference between this instrument
of flight and all others in nature. It is not, except during
actual growth, a part of the living organism, but a mechanical
instrument which the organism has built up, and which then
ceases to form an integral portion of it — is, in fact, dead mat-
ter. Hence, in no part of the fully grown feather is there
any blood circulation or muscular attachment, except as re-
gards the base, which is firmly held by the muscles and ten-
dons of the rudimentary hand (fore limb) of the bird. This
beautiful and delicate structure is therefore subject to wear
and tear and to accidental injury, but probably more than any-
thing else by the continuous attrition during flight of dust-
laden air, which, by wearing away the more delicate parts
of the barbules, renders them less able to fulfil the various
purposes of flight, of body-clothing, and of concealment, as well
as the preservation of all those colours and markings which are
especially characteristic of each species, and generally of each
sex separately, and which, having all been developed under the
law of utility, are often as important as structural characters.
Provision is therefore made for the annual renewal of every
feather by the process called moulting. The important wing-
feathers, on which the very existence of most birds depends,
are discarded successively in pairs at such intervals as to allow
the new growth to be Avell advanced before the next pair are
thrown off, so that the bird never loses its power of flight,
though this may be somewhat impaired during the process.
The rest of the plumage is replaced somewhat more rapidly.
This regrowth every year of so complex and important a
part of a bird's structure, always reproducing in every feather
PROOFS OF OEGAKISIKG MIIS'J) 315
the size and shape characteristic of the species, Avhile each of
the often very diverse feathers grows in its right place, and re-
produces the various tints and colours on certain parts of every
feather which go to make up the characteristic colours, markings,
or ornamental plumes of each species of bird, presents us with
the most remarkable cases of heredity, and of ever-present ac-
curately directed growth-power, to be found in the whole range
of organic nature.
The Nature of Growth
The growth of every species of organism into a highly com-
plex form, closely resembling one or other of its parents, is so
universal a fact that, \vith most people, it ceases to excite won-
der or curiosity. Yet it is to this day absolutely inexplicable.
No doubt an immense deal has been discovered of the mech-
anism of growth, but of the nature of the forces at work, or of
the directive agencies that guide and regulate the forces, we
have nothing but the vaguest hints and conjectures. All
growth, animal or vegetable, has been long since ascertained to
begin with the formation and division of cells. A cell is a
minute mass of protoplasm, a substance held to be the physical
basis of life. This is, chemically, the most complex substance
known, for while it consists mainly of four elements — car-
bon, hydrogen, nitrogen, and oxygen — it is now ascertained
that eight other elements are always present in cells composed
of it — sulphur, phosphorus, chlorine, potassium, sodium,
magnesium, calcium, and iron. Besides these, six others are
occasionally found, but are not essential constituents of pro-
toplasm. These are silicon, fluorine, bromine, iodine, alumi-
nium, and manganese.^
Protoplasm is so complex a substance, not only in the num-
ber of the elements it contains, but also in the mode of their
chemical combination, that it is quite beyond the reach of
chemical analysis. It has been divided into throe groups of
chemical substances — proteids, carbohydrates, and fats. The
1 Verworu's General Physiology, p. 100.
316 THE WOKLD OF LIFE
first is always present in cells, and consists of five elements —
carbon, hydrogen, sulphur, nitrogen, and oxygen. The two
other groups of organic bodies, carbohydrates and fats, con-
sist of three elements only — carbon, hydrogen, and oxygen, the
carbohydrates forming a large proportion of vegetable products,
the fats those of animals. These also are highly complex in
their chemical structure, but being products rather than the
essential substance of living things, they are more amenable
to chemical research, and large numbers of them, including
vegetable and animal acids, glycerin, grape sugar, indigo,
caifeine, and many others, have been produced in the labora-
tory, but always by the use of other organic products, not from
the simple elements used by nature.
The atomic structure of the proteids is, however, so wonder-
fully complex as to be almost impossible of determination.
As examples of recent results, haemoglobin, the red colouring
matter of the blood, was found by Preyer in 1866 to be as
follows —
^eoo-tlgeo-^ 154-'^ ^1^3^179?
showing a total of 1894 atoms, while Zinoffsky in 1855 found
the same substance from horse's blood to be —
C'7i2-tiii3o-'^ 214^245!' 6l^2>
showing a total of 2301 atoms. Considering the very small
number of atoms in inorganic compounds, and in the simpler
vegetable and animal products, caffeine containing only 23
(C7H7(CH3)N402), the complexity of the proteids will be
more appreciated.
Professor Max Verworu, from whose gTeat work on General
Physiology the preceding account is taken, is very strong in
his repudiation of the idea that there is such a thing as a
'' vital force." He maintains that all the powers of life reside
in the cell, and therefore in the protoplasm of which the cell
consists. But he recognises a great difference between the
PEOOFS OF OKGANISING MIND 317
dead and the living cell, and admits that our knowledge of the
latter is extremely imperfect. He enumerates many differ-
ences between them, and declares that '' substances exist in liv-
ing which are not to be found in dead cell-substance." He
also recognises the constant internal motions of the living cell,
the incessant waste and repair, while si ill preserving the highly
complex cell in its integrity for indefinite periods; its resist-
ance during life to destructive agencies, to which it is exposed
the moment life ceases ; but still there is no '" vital force " —
to postulate that would be unscientific.
Yet in this highly elaborate volume of 600 closely printed
pages, dealing with every aspect of cell-structure and physiol-
ogy in all kinds of organisms, he gives no clue whatever to the
existence of any directive and organising powers such as are
absolutely essential to preserve even the unicellular organism
alive, and which become more and more necessary as we pass
to the higher animals and plants, with their vast complexity
of organs, reproduced in every successive generation from
single cells, which go through their almost infinitely elaborate
processes of cell-division and recomposition, till the whole vast
complex of the organic machinery ■ — the whole body, limbs,
sense, and reproductive organs — are built up in all their per-
fection of structure and co-ordination of parts, such as char-
acterises every living thing !
Let us now recur to the subject that has led to this digres-
sion — the feathers of a bird. We have seen that a full-gi'own
wing-feather may consist of more than a million distinct parts
— the barbules, which give the feather its essential character,
whether as an organ of flight or a mere covering and heat-pre-
server of the body. But these barbules are themselves highly
specialised bodies with definite forms and surface-texture,
attaching each one to its next lateral barbule, and, by a kind
of loose hook-and-eye formation, to those of the succeeding
barb. Each of these barbules must therefore be built up of
many thousands of cells (probably many millions), differing
considerably in form and powers of cohesion, in order to pro-
318 THE WORLD OE LIFE
cluce the exact strength, elasticity, and continuity of the whole
web.
Now each feather " grows/' as we say, out of the skin, each
one from a small group of cells, which must be formed and
nourished by the blood, and is reproduced each year to replace
that which falls away at moulting time. But the same blood
supplies material for every other part of the body — builds
up and renews the muscles, the bones, the viscera, the skin,
the nerves, the brain. What, then, is the selective or directing
power which extracts from the blood at every point where
required the exact constituents to form here bone-cells, there
muscle-cells, there again feather-cells, each of which possesses
such totally distinct properties ? And when these cells, or
rather, perhaps, the complex molecules of which each kind of
cell is formed, are separated at its special point, w^hat is the
constructive power wdiich welds them together, as it were, in
one place into solid bone, in another into contractile muscle, in
another into the extremely light, strong, elastic material of the
feather — the most unique and marvellous product of life ?
Yet again, wdiat is the nature of the power which deteiToines
that every separate feather shall always " grow " into its exact
shape ? For no two feathers of the twenty or more which
form each wing, or those of the tail, or even of the thousands
on the whole body, are exactly alike (except as regards the
pairs on opposite sides of the body), and many of these are
modified in the strangest way for special purposes. Again,
what directive a2:encv determines the distribution of the col-
ouring matter (also conveyed by the blood) so that each feather
shall take its exact share in the production of the whole pattern
and colouring of the bird, which is immensely varied, yet
always symmetrical as a whole, and has always a purpose,
either of concealment, or recognition, or sexual attraction in
its proper time and place ?
Xow, in none of the volumes on the physiology of animals
that I have consulted can I find any attempt whatever to
grapple Avith this fundamental question of the directive power
PROOFS OF ORGANISING MIND 319
that, in every case, first secretes, or as it were creates, out of
the protoplasm of the blood, special molecules adapted for the
2:>roductiou of each malcrial — bone, muscle, nerve, skin, hair,
feather, etc. etc., — carries these molecules to the exact part
of the body where and when they are required, and brings into
play the complex forces that alone can 1)uild up with (ri-eat
rapidity so strangely complex a structure as a feather adapted
for flight. Of course the difficulties of conceiving how this
has been and is being done before our eyes is nearly as great
in the case of any other specialised part of the animal body;
but the case of the feathers of the bird is unique in many ways,
and has the advantage of being wdiolly external, and of being
familiar to every one. It is also easily accessible for examina-
tion either in the living bird or in the detached feather, which
latter offers wonderful material for microscopic examination
and study. To myself, not all that has been written about
the properties of protoplasm or the innate forces of the cell,
neither the physiological units of Herbert Spencer, the pan-
genesis hypothesis of Darwin, nor the continuity of the germ-
plasm of Weismann, throw the least glimmer of light on this
great problem. Each of them, especially the last, help us to
realise to a slight extent the nature and laws of heredity, but
leave the great problem of the nature of the forces at work in
growth and reproduction as mysterious as ever. IModern
physiologists have given us a vast body of information on the
structure of the cell, on the extreme complexity of the proc-
esses which take place in the fertilised ovum, and on the exact
nature of the successive changes up to the stage of maturity.
But of the forces at work, and of the power which guides those
forces in building up the whole organ, we find no enlighten-
ment. They will not even admit that any such constructive
guidance is required !
*
A Physiological Allegory
For an imaginary parallel to this state of tliinirs, let us
suppose some race of intellia'cut beings wlio have tlie j)Ower
320 THE WORLD OF LIFE
to visit the earth and see what is going on there. But their
faculties are of such a nature that, though they have perfect
perception of all inanimate matter and of plants, they are
absolutely unable either to see, hear, or touch any animal living
or dead. Such beings would see everywhere matter in motion,
but no apparent cause of the motion. They would see dead
trees on the ground, and living trees being eaten away near
the base by axes or saws, which w^ould appear to move spon-
taneously; they would see these trees gradually become logs
by the loss of all their limbs and branches, then move about,
travel along roads, float down rivers, come to curious machines
by which they are split up into various shapes ; then move
away to where some great structure seems to be growing up,
where not only wood, but brick and stone and iron and glass
in an infinite variety of shapes, also move about and ultimately
seem to fix themselves in certain positions. Special students
among these spirit-inquirers would then devote themselves to
follow back each of these separate materials — the wood,
the iron, the glass, the stone, the mortar, etc. — to their sep-
arate sources; and, after years thus spent, would ultimately
arrive at the great generalisation that all came primarily out
of the earth. They would make themselves acquainted with
all the physical and chemical forces, and would endeavour to
explain all they saw by recondite actions of these forces. They
would argue that what they saw was due to the forces they
had traced in building up and modifying the crust of the
earth ; and to those who pointed to the result of all this ^' mo-
tion of matter " in the finished product — the church, the
mansion, the bridge, the railway, the huge steamship or cotton
factory or engineering works — as positive evidence of design,
of directive power, of an unseen and unknown mind or minds,
they would exclaim, " You are wholly unscientific ; we know
the physical and chemical forces at work in this curious world,
and if we study it long enough we shall find that known forces
will explain it all."
If we suppose that all the smaller objects, even if of the
PEOOFS OF ORGANISING MIXD :]21
same size as ourselves, enn only he seen by microscopes, and
that with improved instruments the various tools we use, as
well as our articles of furniture, our food, and our tahlc-fit tings
(knives and forks, dishes, glasses, etc., and even our watches,
our needles and pins, etc.) become perceptible, as well as the
food and drinks which are seen also to move about and dis-
appear; and when all this is observed to recur at certain def-
inite intervals every day, there woidd be great jubihition over
the discovery, and it would be loudly proclaimed that with
still better microscopes -all would be explained in terms of
matter and motion !
That seems to me very like the position of modern physiol-
ogy in regard to the processes of the growth and development
of living things.
Insects and their Metamorphosis
We now have to consider that vast assemblage of small
winged organisms constituting the class Insect a, or insects,
which may be briefly defined as ringed or jointed (annuluse)
animals, with complex mouth-organs, six legs, and one or two
pairs of wings. They are more numerous in species, and
perhaps also in individuals, than all other land-animals put
together; and in either their larval or adult condition supi)ly
so large and important a part of the food of birds, that the
existence of the latter, in the variety and abundance we now
behold, may be said to depend upon the former.
The most highly developed and the most abundant of the
insect tribes are those which possess a perfect metamorphosis,
that is, which in their larval state are the most comi)letely
unlike their perfect condition. They comprise the great orders
Lepidoptera (butterflies and moths), Coleojitera (beetles),
Hymenoptera (bees, ants, etc.), and Diptc^-a (two-winged
flies), the first and last being those which are perha])s the most
important as bird-food. In all these orders the eggs produce
a minute aTub, maggot, or caterpillar, a- they are variously
called, the first havino- a distinct head but no legs, the second
322 THE WORLD OF LIFE
neither head nor legs, while the third have both head and legs,
and are also variously coloured, and often possess spines, horns,
hair-tufts, or other appendages.
Every one knows that a caterpillar is almost as different
from a butterfly or moth in all its external and most of its
internal characters, as it is possible for any two animals of
the same class to be. The former has six short feet with
claws and ten fleshy claspers; the latter, six legs, five- jointed,
and with subdivided tarsi; the foi-mer has simple eyes, biting
jaws, and no sign of wings; the latter, large compound eyes,
a spiral suctorial mouth, and usually four large and beauti-
fully coloured wrings. Internally the whole muscular system
is quite different in the two forms, as well as the digestive
organs, while the reproductive parts are fully developed in
the latter only. The transformation of the larva into the per-
fect insect through an intervening quiescent pupa or chrysalis
stage, lasting from a few days to several months or even years,
is substantially the same process in all the orders of the higher
insects, and it is certainly one of the most marvellous in the
whole organic world. The untiring researches of modern ob-
servers, aided by the most perfect microscopes and elaborate
methods of preparation and observation, have revealed to us
the successive stages of the entire metamorphosis, which has
thus become more intelligible as to the method or succession
of stages by which the transformation has been effected, though
leaving the fundamental causes of the entire process as mys-
terious as before. Years of continuous research have been
devoted to the subject, and volumes have- been Avritten upon it.
One of the most recent English writers is Mr. B. Thompson
Lowne, F.E.C.S., who has devoted about a quarter of a cen-
tury to the study of one insect — the common blow-fly — on
the anatomy, physiology, and development of w^hich he has
published an elaborate work in two volumes dealing with every
part of the subject. He considers the two-winged flies to be
the highest development of the insect-type ; and though they
have not been so popular among entomologists as the Coleoptera
PEOOFS OF ORGAXISLXG MLXl)
and Lepidoptera, he believes them to be the most nnmenjus in
species of all the orders of insects. 1 will now endeavour to
state in the fewest words possible tbe general results of his
studies, as well as those of the students of the other orders
mentioned, which are all in substantial agreement.
In those insects which have the least comi)lete metamorpho-
sis — the cockroaches — the young emerge from the egg with
the same general form as the adult, but with rudimentarv
wings, the perfect wrings being acquired after a succession of
moults. These seem to be the oldest of all insects, fossilised
remains of a similar type being found in the Silurian forma-
tion. Locusts and Hemiptera are a little more advanced, and
are less ancient geologically. Between these and the four
orders with complete metamorphosis there is a great gap, which
is not yet bridged over by fossil forms. But from a minute
study of the development of the egg, which has been examined
almost hour by hour from the time of its fertilisation, the
conclusion has been reached, that the great difference we now
see between the larva and imago (or perfect insect) has been
brought about by a double process, simultaneously going on,
of progression and retrogression. Starting from a form some-
what resembling the cockroach, but even lower in the scale of
organisation, the earlier stages of life have become more sim-
plified, and more adapted (in the case of Lepidoptera) for
converting living tissues of plants into animal protoplasm, thus
laying up a store of matter and energy for the development
of the perfect insect ; wdiile the latter form has become so fully
developed as to be almost independent of food-supply, by being
ready to carry out the functions of reproduction within a few
days or even hours of its emergence from the pupa case.
At first this retrogression of the first stage of growth towards
a simple feeding machine took place at the period of the suc-
cessive moults, but it being more advantageous to hav(^ the
larva stage wholly in the form best adaptcMl for the storing up
of living protoplasm, the retrogressive variations became stop
by step earlier, and at length occurred within the egg. At
324 THE WOELD OF LIFE
this early period certain rudiments of wings and other organs
are represented by small groups of minute cells termed by
Weismann imaginal discs, which were determined by him to
be the rudiments of the perfect insect. These persist un-
changed through the whole of the active larval stage ; but as
soon as the final rest occurs preliminary to the last moult, a
most wonderful process commences. The whole of the internal
organs of the larva — muscles, intestines, nerves, respiratory
tubes, etc. — ■ are gradually dissolved into a creamy pulp ; and
it has further been discovered that this is effected through the
agency of white blood-corpuscles or phagocytes, which enter
into the tissues, absorb them, and transform them into the
creamy pulp referred to. This mass of nutritive pulp thence-
forth serves to nourish the rapidly growing mature insect, with
all its wonderful complication of organs adapted to an entirely
new mode of life.
There is, I believe, nothing like this complete decomposi-
tion of one kind of animal structure and the regrowth out of
this broken-down material — which has thus undergone decom-
position of the cells, but not apparently of the protoplasmic
molecules — to be found elsewhere in the whole course of
organic evolution; and it introduced new and tremendous dif-
ficulties into any mechanical or chemical theory of growth and
of hereditary transmission. We are forced to suppose that the
initial stages of every part of the perfect insects in all their
wonderful complexity and diversity of structure are formed
in the egg, and that during the subsequent raj^idly growing
development of the larva they remain dormant ; then, that the
whole structure of the fully grown larva is resolved into its
constituent molecules of living protoplasm, still without the
slightest disturbance of the rudimentary germs of the perfect
insect, which at a special moment begin a rapid course of de-
velopmental growth. This growth has been followed, step by
step through all its complicated details, by ^Ir. Lowne and
many other enthusiastic workers , but I will call attention here
PEOOFS OF ORGANISING AilXD 325
only to the special case of the Lepidoptera, l)ocnu>c these are
far more popuLarly known, and the special feature which dis-
tinguishes them from most other insects is fauiiliar to every
one, and can be examined by means of a good pocket lens or
microscope of moderate power. I allude, of course, !<• the
•wonderful scales Avhich clothe the wings of most buttcrllics
and moths, and which produce the brilliant colours and in-
finitely varied patterns with which they are adorned. (){'
conrse, the still more extensive order of the C(deoptera
(beetles) present a similar phenomenon in the cuh^urs and
markings of their wing-cases or elytra, and what is said of
the one order will apply broadly to the other.
The wings of butterflies can be detected in very young
caterpillars when they are only one-sixth of an inch long, as
small out-foldings of the inner skin, which remain unchanged
while the larva is growing; but at the chrysalis (or pupa) stage
the wings ex^iand to about sixty times their former area, and
the two layers of cells composing them then become visible.
At this time they are as transparent as glass ; but two ur three
weeks before emergence of the imago they become opaque white,
and a little later dull yellow' or drab; twenty-four hours later
the true colours begin to appear at the centre of each wing.
It is during the transparent stage that the scales begin tf> Ix*
formed as minute, bag-like sacks filled with protoplasm ; the
succeeding whiteness is caused by the protoplasm being with-
drawn and the sacks becoming filled with air. The pupal
blood then enters them, and from this the colouring matter is
secreted. The scales are formed in parallel lines along ridges
of the corrugated wing membrane. The more bfilliani enloui-s
seem to be produced from the dull yellow ]ugment by cheinical
chanc'es Avhich occur within the scales. A few davs belore
emergence the scales become fullv jxrown, as hii^hlv coniph.'X
structures formed of parallel rows of minute cells, each -cale
with a basal stem which enters a pocket of the skin or mem-
brane, which pockets send out root^ wlii(^h seem to penetrate
326 THE WOKLD OF LIFE
through the skin.^ Another complication is the fact that the
wonderful metallic colours of so many butterflies are not caused
by pigments, but are ^' interference colours " produced by fine
striae on the surface of the scales. Of course, where eye-spots,
fine lines, or delicate shadings adorn the wings, each scale must
have its own special colour, something like each small block
in a mosaic picture.
As this almost overwhelming series of changing events passes
before the imagination, we see, as it were, the gradual but
perfectly orderly construction of a living machine, which at
first appears to exist for the sole purpose of devouring leaves
and building up its own wonderful and often beautiful body,
thereby changing a lower into a higher form of protoplasm.
Its limbs, its motions, its senses, its internal structure, are all
adapted to this one end. Wlien fully grown it ceases to feed,
prepares itself for the great change by various modes of con-
cealment — in a cocoon, in the earth, by suspension against
objects of similar colours, or which it becomes coloured to
imitate — rests awhile, casts its final skin, and becomes a
pupa. Then follows the great transformation scene, as in the
blow-fly. All the internal organs which have so far enabled
it to live and grow — in fact, the whole body it has built up,
with the exception of a few microscopic groups of cells — be-
come rapidly decomposed into its physiological elements, a
structureless, creamy but still living protoplasm ; and when
this is completed, usually in a few days, there begins at once
the building up of a new, a perfectly different, and a much
more highly organised creature both externally and internally
— a creature comparable in organisation with the bird itself,
for which, as we have seen, it appears to exist. And, in the
case of the Lepidoptera, the wings, far simpler in construc-
tion than those of the bird, but apparently quite as well adapted
to its needs, develop a more or less complete covering of minute
1 This description is from Mr. A. G. Mayer's paper on the Development
of the Wing Scales of Butterflies and Moths (Bull. Mus. Comp. Zool. Harv.
Coll., June 1896), so far as I can give it in a verv condensed abstract.
PEOOFS OF OKGA.XISIXG Ail.XD 327
scales, whose chief or only function aijpears tu be tu paint
them with all the colours and all tlie glittering reflections of
the animal, the vegetable, and the mineral kingdoms, to an
equal if not a greater extent than in the case of the birds them-
selves. The butterflies, or diurnal Le])idoi)tera alone, not only
present us with a range of colour and pattern and of metallic
brilliancy fully equal (probably superior), to that of l)irds,
but they possess also in a few cases and in distinct families,
changeable opalescent hues, in which a pure crimson, or blue,
or yellow pigment, as the incidence of light varies, changes
into an intense luminous opalescence, sometimes resembling a
brilliant phosphorescence more than any metallic or mineral
lustre, as described in the next chapter.
And what renders the wealth of coloration thus produced
the more remarkable is, that, unlike the feathers of birds, tlic
special organs upon which these colours and patterns are dis-
played are not functionally essential to the insect's existence.
They have all the appearance of an added superstructure to
the wing, because in this way a greater and more brilliant
display of colour could be produced than even upon the ex-
quisite plumage of birds. It is true that in some cases, these
scales have been modified into scent-a'lands in the males of
some butterflies, and perhaps in the females of some moths,
but otherwise they are the vehicles of colour alone; and though
the diversity of tint and pattern is undoubtedly useful in a
variety of ways to the insects themselves, yet it is so almost
wholly in relation to higher animals and not to their own kind,
as I have already explained in Cluipter IX. It is generally
admitted that insects with compound eyes possess imperfect
vision, and their actions seem to show that they take little
notice of distant objects, except of lights at night, and only
perceive distinctly what is a few inches or a few feet from
them; while there is no proof tliat they recognise what we term
colour unless as a greater or less amount of light.
But as regards the effect of the shading and coloration of
insects upon the higher animals, who are ahuo^t always their
328 THE WOELD OF LIFE
enemies, there is ample evidence. Almost all students of the
subject admit that the markings and tints of insects often
resemble their environment in a remarkable manner, and that
this resemblance is protective. The eye-like markings, either
on the upper or under surfaces, are often seen to be imitations
of the eyes of vertebrates, when the insect is at rest, and this
also is protective. The brilliant metallic or phosphorescent
colours on the wings of butterflies may serve to distract ene-
mies from attacking a vital part, or, in the smaller species
may alarm the enemy by its sudden flash with change of posi-
tion. But while the colours are undoubtedly useful, the mode
of producing them seems unnecessarily elaborate, and adds a
fresh complication in the way of any mechanical or chemical
conception of their production.
CHAPTER XV
GENEBAL ADAPTATIONS OF PLANTS, ANIMAI.S, AND MAN
The adaptations of plants and animals, more especially as
regards the cross-fertilisation of flowers by insects, forms a
very important part of Darwin's work, and has been fully
and popularly elaborated since by Grant Allen, Sir John Lub-
bock (now Lord Avebury), Hermann ^1 tiller, and many other
writers. I have also myself given a general account of the
whole subject both in my Tropical Xature, and my Darwin-
ism; but as there are some points of importance which, 1 be-
lieve, have not yet been discussed, and as the readers of this
volume may not be acquainted with the vast extent of the evi-
dence, I will here give a short outline of the facts before
showing how it bears upon the main argument of the present
work.
Another reason why it is necessary to recapitulate the evi-
dence is that those w^hose knowledge of this subject is derived
from having read the Origin of Species only, can have no
idea whatever of the vast mass of observations the author of
that work had even then collected on the subject, but found
it impossible to include in it. He there only made a few
general, and often hypothetical, references both to the facts
of insect- fertilisation, and to the purpose of cross-fertilisation.
On the latter point he makes this general statement: " 1 have
come to this conclusion (that flowers are coloured to attract
insects) from finding it an invariable rule that when a flower
is fertilised bv the wind it never has a ciailv-coloured ('or«)lla.''
Then a few lines farther on he advei'ts to beautifullv coloured
fruits and says: "But the beauty servers merely as a guide to
birds and beasts, in order tliat the fruit may be devoured and
the matured seed disseminated: T infer that this is the case
"■20
330 THE WORLD OF LIFE
from having as yet found no exception to the rule that seeds
are always thus disseminated when embedded within a fruit
of any kind if it be coloured of any brilliant tint." ^
Such general statements as those here quoted do not make
much impression. The astonishment and delight of botanists
and plant-lovers can, therefore, be imagined when, a few years
later, by his book on the Fertilisation of Orchids by Insects,
and his papers on the Different Forms of Flowers in the prim-
rose, flax, lythrum, and some others ; he opened up a vast new
world of wonder and instruction which had hitherto remained
almost unnoticed. These were followed up by his volumes
on The Effects of Cross- and Self -Fertilisation (in 1876),
and by that on Different Forms of Flowers on Plants of the
same Species (in 1877) giving the result of hundreds of care-
ful experiments made by himself during many years, serv'ing
as the justification for the few general observations as regards
flowers and insects, which form the only reference to the sub-
ject in the Origin of Species.
The facts now admitted to be established by these various
researches are: (1) that crosses between different individuals
of the same species, either constantly or occasionally, are ben-
eficial to the species by increasing seed-production and vigour
of growth; (2) that there are innumerable adaptations in
flowers to secure or facilitate this cross-fertilisation; (3) that
all irregular flowers — Papilionacese, Labiates, Schrophulari-
acese, Orchidese, and others — have become thus shaped to facil-
itate cross-fertilisation. Darwin's general conclusion, that
" nature abhors perpetual self-fertilisation," has been much
criticised, but chiefly by writers who have overlooked the term
" perpetual." He has also shown how the wonderful variety
in form and structure, and the beauty or conspicuousness of
the colours of flowers, can all be readily explained, on this
theory, through the agency of variation and natural selection,
while by no other theory is any real and effective explanation
possible. But besides these there are very numerous other
1 Origin of Species, 6th edition, p. 161.
GEXEKAL ADAPTATIOXS 331
adaptations in flowers to secure them from injurious insects
or from the effects of rain or wind in damaging the pollen
or the stigmas, as beautifully shown in Kerncr's very inter-
esting volume on Flowers and their Unhidden Guests — a
book that forms an admirable sequel to Darwin's works, and
is equally instructive and interesting.
Of late years writers wdio are very imperfectly acquainted
wdth the facts proclaim loudly that Darwin's views are dis-
proved, on account of some apparent exceptions to the general
conclusions he has reached. Two of these mav he here noticed
as illustrative of the kind of opposition to which Darwinism
is exposed. The bee-orchis of our chalky downs, though con-
spicuously coloured and with a fully-developed labellum, like
the majority of its allies wdiich are cross-fertilised by insects,
yet fertilises itself and is never visited by insects. This has
been held to show that Darwin's views must be erroneous,
notwithstanding the enormous mass of evidence on which they
are founded. But a further consideration of the facts shows
that they are all in his favour. In the south of Europe, while
the bee-orchis is self-fertilised as in England, several allied
species are insect-fertilised, bnt they rarely produce so many
seed-capsules as ours; but, strange to say, an allied species
(OpJirys scolopax) is in one district fertilised by insects only,
while in another it is self-fertilised. Again, in Portugal,
w^here many species of Ophrys are found, very few of the
flowers are fertilised and very few ripe seed-ca])snles are pro-
duced. But owing to the great number of seeds in a eapsuU',
and their easy dispersal by wind, the plants are ahnn(hint.
These and many other facts show that tor some unknown
cause, orchises which are exclusively insect-fertilised, are liable
to remain unfertilised, and when that is the rase it becomes
advantageous to the species to be able to f(M*tilise itself, and
this has occurred, partially in many species, and (•(•mpletely
in our bee-orchis.
I may remark here llint lhe name " l>ee-orchis " Is mislead-
ing, as the flower does nol resemble any of our bee-. But the
332 THE WORLD OE LIFE
very closely allied '^ spider orchises " resemble spiders mucli
more closely. It occurs to me, therefore, that the general
resemblance to bee or spider may occasionally prevent the
flowers being eaten off by sheep or lambs, to Avhom even spiders
on their noses or lips would be disagreeable.
Mr. Henry O. Forbes observed, in Sumatra, that many trop-
ical orchids with show^y flowers, wdiich were perfectly adapted
for insect-fertilisation, yet produced very few seed-capsules,
and in many cases none. Yet the great abundance of seeds,
as fine as dust, in a single capsule, together with the long life
of most orchids, is quite sufficient, in most cases, to preserve
the various species in considerable abundance. When, how-
ever, there is any danger of extinction the great variability of
orchids, which at first enabled them to become so highly spe-
cialised for insect-fertilisation, also enables them (in some
cases) to return to self-fertilisation as in our bee-orchis.
Should this continuous self -fertilisation at length lead to a weak
constitution, then, occasional variations serving to attract in-
sects by nectar or in other ways, with minute alterations of
structure may again lead to fertilisation by insects.
The other popular objection recently made to Darwin's views
on the origin of the flowers is, that the colours and shapes of
flowers are often such as to deter herbivorous animals from
eati-ng them, and that this is the main or the only reason why
flowers are so conspicuous. The special case supposed to prove
this is that some buttercups are not eaten by cattle because
they are acrid or poisonous, and that the bright yellow colour
is a warning of inedibility.
Even if these statements were wdiolly correct they would not
in the least affect the general proposition that all conspicuous
flowers attract insects which do actually cross-fertilise them.
But, in the first place, there is much difference of opinion as
to the inedibility of buttercups by cattle; and, in the second,
our three most common yellow buttercups (Banunculus acris,
R. repens, and R. huJhosus) are so constructed that they can
be cross-fertilised by a great variety of insects, and as a mat-
GENERAL ADAPTATIONS
O '> o
ter of fact are so fertilised. IT. Miillcr grouped those lliroe
species together, as the same insects visit them all, and lie
found that thej were attractive to no less than sixty diilerent
species, including 23 flies, 11 beetles, 2-1 bees, wasps, etc., and
5 butterflies.
Any readers who are not satisfied with Darwin's own state-
ments on this subject should examine :\Iiill(M''s Fcrtili-atinn
of Elowers (translated by D'Arcy W. Thonii)son), in whirh
details are given of the fertilisation of abuut 100 species of
alpine plants by insects, while a General "Retrospect gives a
most valuable summary of the conclusions and teadiings on
the whole subject. As regards the general question of the u^^
and purposes of colour in nature the late Grant Allen's inter-
esting and philosophical work on The Colour Sense >hnuld bo
studied. Any one who does so will be satisfied of the general
truth of Darwin's doctrines though there are a few errors in
the details. As an example of the fascinatinjr stvle of the
book I will quote the following paragraph comparing insect-
agency with that of man in modifving and beautit'vinfr the
face of nature. After describing the great alterations man
has made, and the large areas he has modified for his own
purposes, the author thus proceeds :
"But all these alterations are mere surface scratches coniparod
with the immense revolution wrought in the features of nature l\v
the unobtrusive insect. Half the flora of tlie earth has taken the
imprint of his likes and his necessities. While man has only tilK'd
a few level plains, a few great river-valleys, a few peninsular moun-
tain slopes, leaving the vast mass of earth unloudied hy liis hand,
the insect has spread himself over every land in a thousand sliapes,
and has made the whole flowering creation sul)servient to liis daily
wants. His buttercup, his dandelion, and his meadow-sweet grow-
thick in every English field. TTis thyme elothes the hill-side: his
heather purples the bleak grey moorland. HiLrh up among the
Alpine heights his gentian spreads itsi'lf in lakes of blue: amid
the snows of the Himalayas his rhododendrons gleam with crimson
light. The insect has thus turned the whole surface of the eartli
334 THE WORLD OF LIFE
into a boundless flower-garden, which supplies him from year to
year with pollen or honey, and itself in turn gains perpetuation by
the baits it offers for his allurement."
Although I wholly agree with my lamented friend in attrib-
uting the origin and development of flowers to the visits of
insects, and the consequent advantage of rendering many spe-
cies of flowers conspicuous and unlike others flowering at the
same time, thus avoiding the waste and injury of the frequent
crossing of distinct species, yet I do not consider that the
whole of the phenomena of colour in nature is thereby ex-
plained.
In my book on Tropical E'ature I devoted two chapters to
the Colours of Animals and Plants, and I opened the discussion
with the following remarks, which indicate my present views
on the subject. I will, therefore, give a few passages here:
" There is probably no one quality of natural objects from which
we derive so much pure intellectual enjoyment as from their col-
ours. The heavenly blue of the firmament, the glowing tints of
sunset, the exquisite purity of the snowy mountains, and the end-
less shades of green presented by the verdure-clad surface of the
earth, are a never-failing source of pleasure to all who enjoy the
inestimable gift of sight. Yet these constitute, as it were, but the
frame and background of a marvellous and ever-changing picture.
In contrast with these broad and soothing tints, we have presented
to us, in the vegetable and animal worlds, an infinite variety of
objects adorned with the most beautiful and the most varied hues.
Flowers, insects, and birds are the organisms most generally orna-
mented in this way; and their symmetry of form, their variety of
structure, and the lavish abundance with which they clothe and
enliven the earth, cause them to be objects of universal admiration.
The relation of this wealth of colour to our mental and moral na-
ture is indisputable. The child and the savage alike admire the
gay tints of flower, bird, and insect; while to many of us their
contemplation brings a solace and enjoyment which is wholly ben-
eficial. It can then hardly excite surprise that this relation was
long thought to afford a sufficient explanation of the phenomena
GENERAL AD.U^TATIOXS 335
of colour in nature, and this received great support from the dilTi-
culty of conceiving any other use or meaning in the colours with
which so many natural objects are adorned. Why should the
homely gorse be clothed in golden ruiiiiuiit, and the prickly cactus
be adorned with crimson bells? Why sliould our fields be gay with
buttercups, and the heather-clad mountains be clad in purple robes?
Why should every land produce its own peculiar floral gems, and
the alpine rocks glow with beauty, if not for the contemplation and
enjoyment of man? What could be the use to the butterfly of
its gaily-painted wings, or to the humming-bird of its jewelled
breast, except to add the final touches to a world-picture calculated
at once to please and to refine mankind? And even now, with all
our recently acquired knowledge of this subject, who shall say
that these old-world views were not intrinsically and fundamentally
sound; and that although we now know that colour has * uses '
in nature that we little dreamt of, yet the relations of those colours
— or rather of the various rays of light — to our senses and emo-
tions may not be another, and more important use which they sub-
serve in the great system of the universe ? "
The above passage was written more than forty years ago,
and I now feel more deeply than ever that the concluding
paragraph expresses a great and fundamental truth. Although
in the paragraph succeeding that which I have quoted from
Grant Allen's book, he refers to my view (stated above) as
being '' a strangely gratuitous hypothesis," I now propose to
give a few additional reasons for thinking it to be subr^tantially
correct.
The first thing to be noticed is, that the insects whose per-
ceptions have led to the production of variously coloured flowers
are so very widely removed from all the higher animals (birds
and mammals) in their entire organisation that we have no
right to assume in them an identity, or even a similarity, of
sensation with ourselves. That they see is certain, but that
their sensation of sight is the sanio ns our own. or even at all
closely resembling it, is highly improbable Still niorc improb-
able is it that their perception of oolour i< the same as ours,
their organ of sight and their whole nervous system being so
336 THE WORLD OF LIFE
very different, and the exact nature of their senses being un-
known. Even a considerable percentage of men and women
are more or less colour-blind, yet some diversity of colour is
perceived in most cases. The purpose of colour in relation
to insects is that they should distinguish between the colours
of flowers which are otherw^ise alike and which have no per-
fume. It is not at all necessary that the colours we term blue,
purple, red, yellow, etc., should be seen as we see them, or
even that the sight of them should give them pleasure.
Again, the use of colour to us is by no means of the same
nature as it is to insects. It gives us, no doubt, a greater
facility of differentiating certain objects, but that could have
been obtained in many other ways — by texture of surface,
by light and shade, by diversity of form, etc., and in some
cases by greater acuteness of smell ; and there are very few
uses of colour to us which seem to be of " survival value ''- —
that is, in which a greater or less acuteness of the perception
would make any vital difference to us or would lengthen our
lives. But if so, the exquisite perception of colour we nor-
mally possess could not have been developed in our ancestors
through natural selection ; while what we call the '^ aesthetic
sense,'' the sense of beauty, of harmony, of indescribable charm,
which nature's forms and colouring so often gives us is still
further removed from material uses. Another consideration
is, that our ancestors, the Mammalia, derived whatever colour-
sense they possess almost wholly from the attractive colours
of ripe fruits, hardly at all from the far more brilliant and
varied colours of flowers, insects, and birds. But the colours
of wild fruits, which have been almost entirely developed for
the purpose of attracting birds to devour them and thus to
disperse their seeds, are usually neither very brilliant nor
very varied, and are by no means constant indications to us
of what is edible. It might have been anticipated, therefore,
that our perception of colour would have been inferior to that
of birds and mammals generally, not, as is almost certainly
the case, very much superior, and so bound up Avith some of
GENERAL ADAPTATIONS
.» .1 T
our higher intellectual achievements, tiial \Uv total absence
of perception of colour would have checked, or pi rliaps wholly
prevented, all those recent discoveries in spcctrosc^opy which
now form so powerful a means of acquiring an extended knowl-
edge of the almost illimitable universe.
I venture to think, therefore, that we Jiave good reason to
believe that our colour-perceptions have not been developed in
us solely by their survival-value in the struggle for existenee ;
which is all ^ve could have acquired if the views of such think-
ers as Grant Allen and Professor Ilaeckel represent the wln.b*
truth on this subject. They seem, on the other hand, to have
been given us with our higher aesthetic and moral attributes,
as a part of the needful equipment of a being whose spiritual
nature is being developed, not merely to satisfy material needs,
but to fit him for a higher and more enduring life of continued
progress.
Colours of Fruits: a Suggestion as to Nuts
As flow^ers have been developed through insects, so have
edible fruits been developed and coloured so that birds may
assist in the dispersal of their seeds ; while inedible fruits have
acquired endlessly varied hooks or sticky exudations in ord<'r
that they may attach themselves to the fur of quadrupeds or the
feathers of birds, and thus obtain extensive dissemination. All
this was clearly seen and briefly stated by Darwin, and has
been somewdiat fully developed by myself in the work already
quoted: but there is one point on which I wish to mai:i* an
additional suggestion.
In my Tropical Nature I referred to Grant Allen's view
(in his Physiological Esthetics) that nuts were '' not intended
to be eaten"; and in my Darwinism (p. 305) I adopted this
as being almost self-evident, because, though very largely edible,
they are always protectively coloured, being green when unrijKi
and brow^n when they fall u])ou the ground among the decay-
ino" folia2:e. ^foreover, thoir outer-coverings arc often prickly,
as in the sweet-chestnut, or bitter as in the walnut, while their
338 THE WORLD OF LIFE
seed-boxes are often very hard, as in the hazel-nut, or intensely
so_, as in the Brazil-nut and many other tropical species.
But, on further consideration, 1 believe that this apparently
obvious conclusion is not correct; and that nuts are, as a rule,
intended to be eaten. I am not aware that this question has
yet been discussed by botanists, and as it is one of much inter-
est and exhibits one of the curious and indirect ways in which
nature works for the preservation of species, both in the vege-
table and animal world, I will briefly explain my views.
The first point for our consideration is, that most nuts are
edible to some animals, and a large number are favourite foods
even to ourselves. Then they are all produced on large trees
or shrubs of considerable longevity, and the fruits (nuts,
acorns, etc.) are produced in enormous quantities. If now
we consider that in all countries which are undisturbed by
man, the balance between forest and open country, and be-
tween one species and another, only changes very slowly as
the country becomes modified by geographical or cosmical
causes, we recognise that, as in the case of animals, the number
of individuals of each species is approximately constant, and
there is, broadly speaking, no room for another plant of any
particular kind till a parent plant dies or is destroyed by fire
or tempest. Imagine then the superfluity of production of
seed in an oak, a beech, or a chestnut forest; or in the nut-
groves that form their undergrowth in favourable situations.
Countless millions of seeds are produced annually, and it is
only at long intervals of time, when any of the various causes
above referred to have left a space unoccupied, that a few
seeds germinate, and the best fitted survives to grow into a
tree which may replace its predecessor.
But when every year ten thousand millions of seeds fall
and cannot produce a tree that comes to maturity, any cause
which favoured their wider dispersal would be advantageous,
even though accompanied by very great destruction of seeds,
and such a cause is found when they serve as food to herbiv-
orous mammals. For most of these go in herds, such as swine,
GENERAL AUAriATlOXS 339
peccaries, deer, cattle, horses, etc., and wlieu .such animals are
startled while feeding and scamper away, two results, useful
to the species whose fruit they are feedin-,^ upon, follow. As
the acorns, chestnuts, etc., usually lie thickly un the ground,
some will be driven or kicked along wiih the herd; an<l this
being repeated many times during a season and year after
year, a number of seeds are scattered Ixyond the limits of the
j^arent trees. By this process seeds will often reach places
they would not attain by ordinary means, and may thus be
effective in extending the range of the species. It would also
often happen that seeds would be trodden into soft or wet
ground and thus be actually planted by the devouring animals;
and being in this case placed out of sight till the herds had
left the district would have a better chance of cominjr to
maturity.
XoAv one such success in a year would more than compensate
to the species for millions of seeds devoured, and it would
therefore be beneficial to a species to produce nuts or seeds of
large size and in great quantities in order to attract numbers
of mammals to feed on them. This is quite in accordance
with nature's methods in other cases, as Darwin has shown in
the case of pollen. The very curious fact of the I5razil-nut
having such a very hard shell to the triangular seeds and a still
harder covering to the globular fruit, which falls from the very
lofty trees without opening, and has to bo broken open with
an axe by the seed-collectors, is another example. This is saiil
not to open naturally to let the seed escape for a year or more ;
and this fact, with its almost perfect globular form, would
facilitate its being scattered to a considerable distance by the
feet of tapirs, deer, or peccaries, and when at last the seeds
fell out, perhaps aided by the teeth or feet of these animals,
some of them would almost certainly be trodden into the
ground, and this would be facilitated by their sidvangidar
shape. If this is the mode of dispersal it has ]u*oved very suc-
cessful, for the species is widely srattorrd iti moderate-sized
groves over a considerable portion of th(^ Amazonian forests.
340 THE WOKLD OF LIFE
The main facts and probabilities clearly point to the conclu-
sion that the extensive group of nut-like fruits or seeds are
intended to be eaten, not by birds while on the trees, but by
ground -feeding animals — to be devoured wholesale, in order
to disperse and save a few which may germinate and produce
another generation of trees.
The Colours of Plants and Animals in relation to Man
The views of Ilaeckel and of the whole school of Monists,
as ^\^e\\ as of most of the followers of Spencer and Darwin,
are strongly antagonistic to the idea that in the various groups
of phenomena w^e have so far touched upon there has been in
any real sense a preparation of the earth for man; and those
who advocate such a theory are usually treated with scorn as
being unscientiiic, or Avith contempt as being priest-ridden.
Darwin himself was quite distressed at my rejection of his
own conclusion — that even man's highest qualities and pow-
ers had been developed out of those of the lower animals by
natural or sexual selection. Several critics accused me of
^' appealing to first causes " in order to get over difficulties ;
of maintainins: that '^ our brains are made bv God and our
lungs by natural selection " ; and that, in point of fact, " man
is God's domestic animal." This was when I published my
Contributions to the Theory of Xatural Selection, in IS 70, its
last chapter on The Limits of ^Natural Selection as applied to
Man, being the special object of animadversion, because I
pointed out that some of man's physical characters and many
of his mental and moral faculties could not have been pro-
duced and developed to their actual perfection by the law of
natural selection alone, because they are not of survival value
in the struggle for existence.
In the present work I recur to the subject after forty years
of further reflection, and I now uphold the doctrine that not
man alone, but the whole World of Life, in almost all its varied
manifestations, leads us to the same conclusion — that to afford
any rational explanation of its phenomena, w^e require to pos-
GENERAL ADAPT AT lOXS 341
tulate the continuous action and guidance of higher intelli-
gences; and further, that these have prul)ahly been working
towards a single end, the development of intellectual, moral,
and spiritual beings. I will now indicate briefly how the facts
adduced in the present and preceding chapters tend to support
this view.
Having shown in the last chapter that the phenomena of
groiuth in the animal world, and especially as manifested in
the feathers of birds and the transformation> of the higlier
insects, are absolutely unintelligible and unthinkable in the
absence of such intelligence, we must go a stc}) further and
assume, as in the highest degree proliable, a pur|)o>c which
this ever-present, directing, and organising intelligence has had
always in view. We cannot help seeing that we ourselves are
the highest outcome of the developmental process on the earth ;
that at the time of our first ajopearance, plants and animals
in many diverging lines had approached their highest develop-
ment; that all or almost all of these have furnished species
"which seem peculiarly adapted to our purposes, whether as
food, as providing materials for our clothing and our varied
arts, as our humble servants and friends, or as gratifying our
highest faculties by their beauty of form and colour : and as
our occupation of the earth has already led to the extinction
of many species, and seems likely ultimately to destroy many
more except so far as we make special efforts to preserve them,
we must, I think, assume that all these consequences of our
development were foreseen, and that results which srrm to bo
so carefully adapted to our wants during our growing civilisa-
tion were really prepared for us. If this be so, it follows that
the much-despised anthropomorphic view of the whole develop-
ment of the earth and of organic nature was, after all, tho
true one.
But if the view now advocated is not so wholly unscientific,
so utterly contemptible as it has hitherto been declared to bo
by many of our great nuthnrities, it is certainly advisable to
show how various facts in nature bear upon it and are ex-
342 .THE WOKLD OF LIFE
plained by it. I will therefore now add a few more consid-
erations to those I have hitherto set forth.
On the question of the colour-sense I have already argued
that though it may exist in birds and insects, it is hardly likely
that it produces any such high aesthetic pleasure as it does in
our own case. All that the evidence shows is, that thev do
perceive what are to us broad differences of colour, but we have
no means whatever of knowing n:]iai they really perceive. It
is a suggestive fact that colour-blind persons, though they do
not see red and green as strongly contrasted as do those with
normal vision, yet do perceive a difference between them. It
is therefore quite possible that birds may see differences be-
tween one strongly marked colour and another without any
sense of what we should term colour, and at all events without
seeing '' colours " exactly as we see them. It is now generally
admitted that birds arose out of primitive reptiles, and from
their very origin have been quite distinct from mammals,
which latter probably diverged a little later from a different
stock and in a somewhat different direction. The eyes of both
were developed from the already existing reptilian eye, and
their type of binocular vision may be very similar. But at
that early period there were, it is believed, no coloured flowers
or edible coloured fruits, and it is probable that the perception
of colour arose at a much later period. It is therefore unlikely
that a faculty separately developed in two such fundamentally
different groups of organisms should be identical in degree or
even in nature unless its use and purpose were identical. But
birds are much more extensive fruit-eaters than are mammals,
the latter, as we have seen, being feeders on nuts which are
protectively tinted rather than on fruits, while their largely
developed sense of smell would render very accurate perception
of colour needless. It is suggestive that the orang-utan of
Borneo feeds on the large, green spiny Darian fruit ; and I
have also seen them feeding on a green fruit which was re-
pulsively bitter to myself. Our nearest relatives among exist-
ing quadrupeds do not therefore seem to have any need of
GExXEEAL ADAPTATiUAS 343
a refined colour-sense. AVliy then should ii have been so highly
developed in us? It was one of the finKhmir^ntnl maxims of
Darwin that natural selection couhl not prudiK-u absolute, but
only relative perfection; and airain, that no species could
acquire any faculty beyond its needs.
The same ar^iments will apply even more strongly in the
case of insects. They appear to recognise the colour-, the
formSj and the scents of flowers, but we can only vagufly guess
at the nature and quality of their actual sensations. Their
whole line of descent is so very far removed from that of the
birds that it is in the highest degree iinpnjbable that there is
any identity even in their lower mental faculties with those
of birds. For the colour-sense is mental, not })hysical ; it
depends partly on the organ of vision, but more fundamentally
on the nature of the nervous tissues which transform the etlects
of light-vibrations into the visual impressions which irc rec-
ognise as colour, and ultimately on some purely mental faculty.
But the colour-sense in insects may be quite other than the
bird's or than our own, and mav in most cases be combined
with scent, and often with form to produce the recognition
of certain objects, which is all they require.
Yet insects, birds, and the flowers and fruits which attract
them, all exhibit to our vision nearlv the same ranjje of the
colour-scheme, and a verv similar intensitv, brilliancv, and
purity of colour in particular cases; which is highly remark-
able if their respective needs were the only etiicient causes in
the production of these colours. Looking first at flow( rs, how
very common and conspicuous are those of a yelh»w colour,
yet far beyond the average are the rich orange petals of tlie
Escholtzia and the glistening splendour of st^me of our butter-
cups; red and purples are innumerable, yet in the Lobelia
fulqens and some other flowers we r(\'ieh an intensity of huo
which seem to us un^urpassahly b(\iutiful; blues of the type
of the campanulas or the v.'irious blue lillaceir are all in tlieir
way charming, but in the blue salvia (Salvia patens) the
spring gentian {Geniiana vcrna), and a few others, we perceive
U4: THE WOJRLD OF LIFE
a depth and a purity of liue which seem to have reached the
limits of the possible. We may surely ask ourselves whether
these exquisite refinements of mere colour as well as the in-
finity of graceful forms, and the indescribable delicacies of
texture and of grouping, are all strictly utilitarian in regard
to insect-visitors and to ourselves. To them the one thing
needful seems to be a sufficient amount of difference of any
kind to enable them to distinguish among species which grow
in the same localitv and flower at the same time.
Special Cases of Bird-colouration
Coming now to birds, we find the colours with which they
are decorated to be fully equal in variety and purity of tint
to those of flowers, but extending still further in modifications
of texture, and in occasionally rivalling minerals or gems in
the brilliancy of their metallic lustre. The exquisite blues
and vinous purples, reds and yellows of the chatterers and
manakins, the glorious metallic sheen of the trogons, of many
of the humming-birds, and of the long-tailed paradise-bird ;
the glistening cinnabar-red of the king-bird of paradise, ap-
pearing as if formed of spun-glass ; the silky orange of the
cock-of-the-rock and the exquisite green of the Malayan crested
gaper, are only a few^ out of thousands of the extreme refine-
ments of colour with which birds are adorned.
Add to these the marvellous ornaments with which the males
are so frequently decorated, the crests varying from the feath-
ery dome of the umbrella bird, to the large richly coloured
crest of the roval flvcatcher of Brazil, and the marvellous blue
plumes from the head of the fern-bearing bird of paradise
(Pteridopliora Alherti), with a thousand others hardly in-
ferior, and we shall more than ever feel the want of some
general and fundamental cause of so much beauty.
All this w'ealth of colour, delicacy of texture and exuber-
ance of ornament, has been explained hitherto as being utili-
tarian in two ways only: (1) that they are recognition-marks
of use to each species, more especially during its differentiation
GEXEKAL ADAI^TATIONS 345
as a species; and (2) as inllucncing female choice of the must
ornamental males, and tlicrclure of use to each species in the
struggle for existence. The former I have, I tliink, proved to
be a true cause; the latter I reject for reasons given ii» my
Darwinism. I there give an alternative solution of the prol>-
lem which I still think to be fundnmontally correct and whicli
has been arrived at by Weismann and others from theoretical
considerations to whicli 1 may advert hiter on.
C olouration of Insects
Passing now to tlie order of insects wliich perhaps pxhil»its
the greatest range of colour-display in the wh(de of the organic
world — especially in the order Lepido])tera, we find the dif-
ficulties in the way of a purely utilitarian solution still greater.
Any one who is ac(iuainted with this order of insects in its
fullest development in the equatorial zone of the great conti-
nents, will recognise liow impossible it is to give any ade<piato
conception of its wealth of colour-decoration by a mere verbal
description, "^'et the attempt must be made in order to com-
plete the argument 1 am founding upon a consideration of the
whole of the facts of orc^anic colouration.
Even in the temperate zones we have a rich display of colour
and marking in our exquisite little blues, our silver-spotted
fritillaries, our red-admiral, our peacock, and our orange-tip
butterflies, and on the Continent, the two swallow-tails, the
apollo butterflies, the fine Chaaxcs Jason, and many other*.
But these are absolutely as nothing compared to the wealth
of colour displayed in the eastern and western tropics, where
the average size is from two to three times ours, and the num-
bers, both in species and individuals at least ten times as great.
Not only is there every tint of red, yellow, Mue and gretMi,
on ground-colours of black or white an<l various slunles of
brown or buff, but we find the most vivid metallic hlues or
silky yellows covering a largi' j)orti<»ii of tlie wing-surface or
displayed in n variety of patteni< ihat i- almost bewildering
in its varietv and beauty.
346 THE WOELD OE LIFE
As a few examples, the Callitliea sapphira of the Amazon
is of a soft, celestial blue that the finest lobelia or gentian
cannot surpass. The grand Oenithoptera Amphrisius, and its
allies has the hind wings of an intense yellow with a silky
lustre, while 0. Prianius and many allied species are richly
adored with metallic green, deep orange, or violet-blue.
Papilio Ulysses of Amboyna equals in size and colour the
splendid blue morphos of South America ; while these latter
not only present us with every shade of blue on insects of
the largest size, but in Morpho cypris, and several allied
species exhibit an intensity of colour and of metallic sheen
that is equal to the highest efforts of nature in this direction
on the caps or the gorgets of humming-birds, on the glittering
shields of the Epimachidse of ^N^ew Guinea, or on such precious
gems as the emerald, the sapphire, the ruby, or the opal.
The exquisite combinations of brilliant colour and endless
variety of pattern to be found among the small Lycsenidae
and Erycinidse of both hemispheres must be passed over; as
well as the somewhat larger Catagrammas whose diversified
upper and under sides are a constant delight; while the vast
groups of the Heliconidse and Danaidse, inedible to most birds
and lizards, are often rendered conspicuous by bold contrasts
of the purest white, yellow, or red, on a blue-black ground.
Some Extremes of Insect-Coloration
There are some examples of tropical butterflies in which
nature may be said to have surpassed herself, and to have
added a final touch to all the beauty of colour so lavishly dis-
played elsewhere. These are to be found in a few species
only in both hemispheres, and are therefore the more remark-
able. The largest butterfly to exhibit this form of colour is
the Ornithoptera magellanus, from the Philippines, whose
golden-yellow wings, when viewed obliquely acquire the chang-
ing hues of polished opals, quite distinct from any of its
numerous allies which possess the same colour but with what
may be termed a silky gloss. In the same part of the world
GEXEEAL ADAriATlOXS 347
(the Bismarck Archipelago) there is a day-flyinn; i,„,th
(Burgena chalyhcata), one of the A<:aristifhi', wIkjso wings
change from Mack to blue and a fiery opalcsci-nt red. In
tropical America there is a group (»f hutterilies of tlic g«-nii8
Papilio, which are very abuii(hiiit botli in species and in«livid-
uals, whose velvet-black wings liav(^ a few bands or -jiois uf
blue or green on the upper pair, while the lower have a ban<l
of spots near the posterior margin of a brilliant cTimsnn.
Among perhaps a hundred species with this general style oi
coloration, there are a few (perhaps a dozen) in which ihe
red of the hind wings, when viewed very obli(iu('ly fn^ni be-
hind, changes into opalescent and then into a curious bluish
phosphorescence of intense brilliancy.
I am informed by Dr. K. Jordan (of the Tring Zoohtgical
Museum) that in these insects the black ground of the wing
changes also into metallic blue, which seems to spread over
the red and to aid in the production of the phosphorescent
effect. This is so marked that ^Ir. Bates gave to one of the
new species he described, the name of Papilu) phosplionis.
One of the small Er^'cinidae (Euseldsia prcvclara) found in
the Upper Amazon valley, is of a yellow butf colour, with a
wonderful opalescent reflection which is said to be tlic most
intense and brilliant in the whole order of Lepidoptera iuid
probably the most brilliant colour known.
All metallic reflections in the animal world are what aro
called interference-colours, and are prttduced by excessively
fine lines or rugosities on polishe<l surfaces, or by ('<iually
thin transparent lamina^. It is probable that in the remark-
able changing glows now described, l)olh these eauses may
come into play, producing, wlion viewed at eertain auirles,
an intensity of hue resembling those of the linest opals, or
sometimes imitating the most brilliant glow-worms or fire-
flies bv means of reflecteil light. It se(Mn< |»rol)able that tliCi^e
rare hues mav be nt' a pi-oleetivc nature, siui-e a pur-ning bird
miiilit be start le(l hv tli*' sudden fla-hinrr out of -n l)rilliant a
light and thus allow the inject to escape: lnu that dor'< not
348 THE WOKLD OF LIFE
render it more probable that the infinitely complex arrange-
ments by which such structures are produced and transmitted
unfailingly to offspring, should have been brought about for
this purpose alone, when thousands of other species arrive
at the same end by far simpler means.
E"ow if there was a difficulty in the view that all the wealth
of colour and beauty in birds has been developed solely on
account of its utility to themselves, that difficulty becomes
greatly increased in the case of these insects. The described
butterflies alone are already far more numerous than birds,
and there are certainly more to be discovered of the former
than of the latter. Bates well observed that the expanded
wings of butterflies seemed to have been used by nature to
write thereon the story of the origin of species. To this we
may, I think, add that she has also used them, like the pages
of some old illuminated missal, to exhibit all her powers in
the production, on a miniature scale, of the utmost possibili-
ties of colour-decoration, of colour-variety, and of colour-
beauty ; and has done this by a method which appears to us
unnecessarily complex and supremely difficult, in order per-
haps to lead us to recognise some guiding power, some supreme
mind, directing and organising the blind forces of nature in
the production of this marvellous development of life and
loveliness.
It must always be remembered that what is produced on
the flow^er, the insect, or the bird, is not colour, but a surface
so constituted in its chemical nature or mechanical texture
as to reflect light of certain w^ave-lengths while absorbing or
neutralising all others. Colour is the effect produced on our
consciousness by light of these special wave-lengths. To claim
that the lower animals, especially the mammals, perceive all
the shades and intensities, the contrasts and the harmonies of
colours as we perceive them, and that they are affected as we
are with their unequalled beauty is a wholly unjustified
hypothesis. The evidence that such sensations of colour exist
in their case is wholly wanting. All wc really know is, that
GENERA!. Al )ArTA TK ).\S :]|;)
they appear to percoivo (lifTcrciicfs wlicn- wc j.. re. nc cnlour,
but it has not hoen ))!•(. vcd liow far tlii- iMi-ccption cxtfinU,
since in the most intollii^^cnl «»f tlu'sc, (|(i«:> and horses, the
sense of smell is so highly developed as for many purposes to
take the place of vision.
It is a very suggestive fact that tho tlioory of tlie develop-
ment of the colour-sense through its utility, receives least s\ij>-
port from those animals Avhich are nearest to us, and from
which we have been corporeally developed — the niannnals;
rather more support from those which have had a \vi(hdy dif-
ferent origin — the birds ; and apparently most from tlioso
farthest removed from us — the insects, for whom it has been
claimed that we owe them all the floral beauty of the vege-
table kingdom, through their refined perception of ditTerences
of form and colour. This seems to me to be a kind of
redudio ad dbsurdum, and to constitute a disproof of that
whole argument as a final cause of the colour-sense. On the
other hand, it gives the strongest support to the view that the
refined perception and enjo\inent of colour ive possess has
not, and could not have been developed in us by its survival-
value in our early struggle for existence, but that these faculties
are, as Huxley remarked in reirard to his eniovment of scenerv
and of music, ^^ gratuitous gifts,'' and as such are powerful
arsninients for ^' a benevolent Author of the Universe/' *
iSee Darwinism (3rd ed. 1901), p. 478, Appendix.
CHAPTEE XVI
THE VEGETABLE KINGDOM IN ITS SPECIAL EELATION
TO MAN
It is obvious that, as animal life has from its very origin
depended upon and been developed in relation to plant life,
the entire organisation of the former would, by the continuous
action of variation and survival of the fittest, become so
harmoniously adapted to the latter, that it would inevitably
have every appearance of the plant having been formed and
preordained for the express purpose of sustaining and benefit-
ing the animal. This harmonious co-adaptation cannot there-
fore be adduced as, of itself, being any proof of design, but
neither is it any proof against it. So with man himself, so
far as his mere animal wants are concerned, his dependence
on plants, either directly or indirectly, for his entire sus-
tenance by food, and therefore for his very life, affords no
grounds for supposing that either of the two kingdoms came
into existence in order to render the earth a possible dwelling-
place for him. But as regards those special qualities in which
he rises so far above all other animals, and especially those
on which the higher races found their claim to be " civilised,"
there seem to be ample grounds for such an argument, as I
hope to be able to show.
Taking first the innumerable different kinds of wood, whose
qualities of strength, lightness, ease of cutting and planing,
smoothness of surface, beauty, and durability, are so exactly
suited to the needs of civilised man that it is almost doubtful
if he could have reached civilisation without them. The con-
siderable range in their hardness, in their durabilitv when ex-
posed to the action of water or of the soil, in their weight
and in their elasticity, render them serviceable to him in a
350
PLANTS IN RELATIOX TO MAX nr>i
thousand ways which arc totally removed from any use made
of them by the lower animals.
Few of these qualities seem essential to themsclvos as vege-
table growths. They might have been much smaller, which
would have greatly reduced their uses; or so much harder as
to be almost unworkable; or so liable to fracture as to ho
dangerous; or subject to rapid decay by the action of air, or
of water, or of sunshine, so as to be suitable for temjuirarv
purposes only. With any of these defects they miirht have
served the purposes of the animal world (piite as well as they
do now; and their actual properties, all varyinir alxuit a mean
value, which serves the infinitely varied purposes to which we
daily and hourly apply them, may certainly be adducc<l as an
indication that they were endowed with such properties in
view of the coming race wdiich could alone utilise them, and
to whose needs they minister in such an infinite variety of
ways.
As one example of what such a different quality of tind)er
as above indicated might mean let us remember that from bo-
fore the dawn of history down to about the middle of the last
century every ship in the world was built of wood. lla<l no
wood existed suitable for sea-going vessels, the whole course of
history, and perhaps of civilisation, would have been dilTerent.
Without ships the Mediterranean would have been almost as
impassable as was the Atlantic. America would be still un-
known, as well as Australia and possibly S..iitli Africa; and
the whole world would be for us smaller than in ilie days be-
fore Columbus. And all this might have happened had tlie
nature of vegetable growth, while dift'ering little in external
form and equally well adapted for unintelligent animal life,
not possessed those special qtuditics which fitted it for minis-
tering to the varied needs of intellectual, inventive, and ever
advancing man.
But, even with the whole vegetable world in \\< (Uitwanl
aspect and mechanical properties exactly as it is now, there
are still a thousand wavs in which it ministers to tlie needs
352 THE WOKLD OF LIFE
of our ever-growing civilisation, whicli have little or no re-
lation to the animal world Avhich grew up in dependence on
it. Leaving out of consideration the vast number of fruits,
and cereals, and vegetables which supply him with varieties
of food, which may be of more importance to man in the
future than thev are now, let us take first the innumerable
drugs which enable him to avoid some of the evils brought
upon himself by his ignorance, his dissipations, or his wilful
neglect. The pharmacopeias of every country and every age
are crowded with the names of herbs and simples used with
more or less success as remedies for the various diseases man
was supposed to be heir to, and if many of these were alto-
gether imaginary, very large numbers still hold their place as
of real and often of inestimable value. To name onlv a few
of the best known, we could hardly dispense with such
common drugs as aloes, arnica, belladonna, calendula, cascara,
gentian, jalap, ipecacuanha, nux vomica, opium, podopholin,
quinine, rhubarb, sarsaparilla, and a host of others.
To these we mav add the various '' balsams " so much used
in ancient surgery — balm of Gilead, friar's balsam, balsam
of Peru, benzoin, camphor, etc.
Then there are the ordinary resins and gums so useful in
the arts — copal, dammar, mastic, kauri, gum-arabic, traga-
canth, asafoedita, gamboge, etc.
Among the numerous dyes are amatto. Brazil-wood, log-
wood, camwood, fustic, indigo, madder, turmeric, and woad.
Vegetable oils, used for cooking, lighting, perfumes,
medicines, etc., are very numerous. Such are candle-nut,
castor oil, coco-nut oil, colza oil, olive oil, cotton seed,
linseed, and rape-seed oils, cajeput oil, and innumerable others
in every part of the world, known or yet to be discovered.
Perfumes and spices are also extremely abundant, such as
caraways, cinnamon, cloves, mace, nutmegs, patchouli, pepper-
mint, orris-root, sandal wood, sassafras, tonquinbeans, vanilla,
and the many essential oils from highly perfumed fruits and
flowers.
PLAXTS l.\ 1 ii: LAT I ().\ To MAX nnn
•JJO
Of foods and drinks not used l).v ihc lower animals, are
arrowroot, tapioca, sa^^), sugar, wine, l.cer, i.-a, eolTee, :ind
cocoa, the last six, wlicn nscd in moderation, Indn-,^ among
the choicest gifts of nature.
There remain a number of vegetaMc pn.diict-^ inv;duahle
for arts and manufaelures — cotton and tlax for (doihing,
hemp for cordage, rattan and bandjoo for tropical furniture,
boxwood for wood-engraving, gutta-percha for machine belts
and a great variety of economic uses, and lastly india-rubU.-r,
one of the greatest essentials of our chemieal and mechanical
arts, without which neither the electric telegraph, the bicycle,
nor the motor-car could have reached their present stage of
perfection, while no doubt many equally important uses re-
main to be discovered.
It may be objected that so many of these varied products
have been shown to be of use to the plants themselves as
protections against injurious insects or from being devoured
in their young state by herbivorous mammals, that their utility
to man is only an accidental result, and of no real signiticancc.
But this objection can hardly be a valid one when we consider
the enormous number of beneficial drugs, highly agreeable
scents and spices, useful oils, and delicious foods or drinks,
that are among the commonest of vegetable bye-products.
There seems no direct connection between juices or volatile oils
which are distasteful to insects, and drugs which are valuable
medicines in the case of human diseases. The leaves or stems
of seedling plants needed only a temporary protection, while
the juices which effect it not only increase in (piantity dur-
ing the whole life of the plant, but are transfornuil into such
as are of unmistakeable value to civilised man. It is almost
inconceivable that the exquisite fragrance tleveloped only by
roasting the seed of the coifee shnd) should be a chance result
of the nature of the juices essential for the well-being of this
particular species; or that the strange mechanical properties
of india-rubber should be developed in a few otdy of the thou-
sands of species having a ])rotective milky sap.
35i THE WOELD OF LIFE
Before leaving this brancli of my subject, 1 must say a few
words on the indications afforded by these varied products
of plant-life, of the absolute necessity of a directive power
and a mind of the highest organising intelligence for their
production. Quite as clearly, perhaps even more clearly than
for the development of the bird's feather or the insect's trans-
formations, does the agency of such a supreme mind seem to
be essential.
Let us consider first the extreme simplicity and uniformity
of the conditions under which such marvellously diverse re-
sults are produced. A very large proportion of the vegetable
products useful to man are obtained from the tropical forests,
where the temperature is more uniform, the moisture more
constant, and the trees less exposed to wind than anywhere
else in the world. The whole organisation of the higher
plants is, as compared with that of animals, extremely simple,
and they are wonderfully similar in structure to each other,
even in distinct genera and natural orders. The roots, the
wood, the bark, the leaves, are substantially of the same type
in thousands of species. All alike build up their structures
out of the same elements, which they obtain from the water
and the few substances it dissolves out of the soil, from the
air and the carbonic acid and aqueous vapour it contains.
Yet under these conditions w^hat a seemingly impossible
variety of products arise.
When the modern chemist attempts to bring about the same
results as are effected by nature in the plant, he has to em-
ploy all the resources of his art. He has to apply great heat
or great cold ; he uses gas or electric fires and crucibles ; he
requires retorts for distillation, and air-tight vessels and tubes
for the action of his reagents, or to preserve his liquid or
gaseous products ; but with all his work, carried out for more
than a century by thousands of earnest students, he has only
been able to reproduce in his laboratory a limited number of
organic substances, while the more important of the constit-
PLAXTS IX IIEJ.ATIOX To MAX 35
oo
UGiits of liviug- urgaiii.Niiis i-cuiaiii I'ar Im'^uikI his pijwcrs of
yynthesis.
The conditions under wldcli rial hit works in ilic vpffotablc
kingdom are the very (jpposite of all this. Starting fr«>ni
the ripened seed, consisting essentially of a single fertilised
cell and a surrounding mass of nutritive material, a root is
sent out into the soil and a shoot into the atmosphere, from
which the whole plant with all its tissues and vessels arc
formed, enabling it to rise up into the air so as to obtain
exposure to light, to lift up tons weight of material in the
form of limbs, branches, and foliage of forest trees, often to
a hundred feet or more above the surface, by means of forces
whose exact mode of operation is still a mysten.^ ; while by
means of the very same tissues and vessels those recondite
chemical processes are being carried on which result in the
infinitely varied products already very brietly referred to.
The living plant not only builds up its own man-ellous
structure out of a few elements supplied to it either in a
gaseous or liquid state, but it also manufactures all the aj>
pliances — cells, vessels, fibres, etc. — needful for its complex
laboratory work in producing the innumerable l)V(v})roducts
possessing so many diverse properties useful to man, but which
were mostly unneeded by the remainder of the animal world.
Usually botanists as well as zoologists are satisfied to de-
scribe the minute structure of the organs of j)lants or animals,
and to trace out as far as possible the changes that occur dur-
ing growth, without any reference to the unknown and un-
intelligible forces at work. As Weismann has state<l, the
fundamental question — ''the causes and mechanism by which
it comes about that they (the germicides or physinlogical
units) are always in the right place and develoj) into colls
at the right time" — is rarely or never touched uptju.'
Modern theories of heredity take for granted the essential
phenomena of life — nutrition, assiniilati(ui, antl growth.
1 Tlie Germ riasiii, p. 4.
356 THE WORLD OY LIFE
I find, however, that Professor Anton Kemer, in his great
■work on The Natural History of Plants, fully recognises this
great fundamental problem, and even recurs to the much
derided " vital force '' as the only help to a solution of it.
He says:
" The phenomena observed in living protoplasm, as it grows and
takes definite form, cannot in their entirety be explained by the
assumption of a specific constitution of protoplasm for every dis-
tinct kind of plant, though this hypothesis may prove useful when
we enquire into the origin of new species."
Again he says:
" In former times a special force was adduced, the force of life.
More recently, when many phenomena of plant-life had been suc-
cessfully reduced to simple chemical and mechanical processes, this
vital force was derided and effaced from the list of natural
agencies. But by what name shall we now designate that force in
nature which is liable to perish whilst the protoplasm suffers no
physical alteration and in the absence of any extrinsic cause; and
which yet, so long as it is not extinct, causes the protoplasm to move,
to enclose itself, to assimilate certain kinds of fresh matter coming
within the sphere of its activity and to reject others, and which
when in full action makes the protoplasm adapt its movements un-
der external stimulation to existing conditions in the manner which
is most expedient?
" This force in nature is not electricity nor magnetism ; it is not
identical with any other natural force; for it manifests a series of
characteristic effects which differ from all other forms of energ}\
Therefore, I do not hesitate again to designate as ' vital force ' this
natural agency, not to be identified with any other, whose immedi-
ate instrument is the protoplasm, and whose peculiar effects we call
life. The atoms and molecules of protoplasm only fulfil the func-
tions which constitute life so long as they are swayed by this vital
force. If its dominion ceases they yield to the operation of other
forces. The recognition of a special natural force of this kind is
not inconsistent with the fact that living bodies may at the same
time be subject to other natural forces" (p. 52).
PLA^s'TS l.\ KEL.VTiO.\ it) .MAX 357
And again, after discussing the various effects pro<luce(l by
that wonderful substance chlorophyll, he says:
" We see the effective apparatus, we niugnisu the f(x)(l-ga.scg
and food-salts collected for working up, wo know that tlie nun's
rays act as the motive force, and we also identify the prodiu-t^
which appear completed in the chloropliyil granules. By careful
comparison of various cells containing chlorophyll, having found
by experience that under certain external conditions the wliole ap-
paratus becomes disintegrated and destroyed, it is indeed permiftrti-
ble to hazard a conclusion about the propelling forces. But what
is altogether puzzling is, how the active forces work, how the sun\s
rays are able to bring it about that the atoms of the raw mat<.'rial
abandon their previous grouping, become displaced, intermix one
with another, and shortly reappear in stable combinations under a
wholly different arrangement. It is the more difficult to gain a
clear idea of these processes, because it is not a question of thai dis-
placement of the atoms called decomposition, but of tliat process
which is known as combination or synUicsis'' (p. 377).
I have made these quotations from one of the greatest Ger-
man \vriters on botany^ in order to show that a professor of
the science, with a most extensive knowledge of every aspect
of plant-life, supports the conclusion I had already reached
from a consideration of some of the broader phenomena of
animal life and organisation. In the last paragraph (pioted
he even shows that phenomena occur during the growth of
the plant, which are, as I suggested from other facts, a»ni-
parable in complexity with those of the metamoqihosis of the
higher insects, and, therefore, equally requiring the agenc}*
of some high directive power for an adequate rati(uuil (explana-
tion of them.
I am quite aware that this view, of the earth and organic
nature having been designed for the development of the Innnan
race, and further, that it has been so dc-iirned that in the
course of its entire cvolutlnn, ii-; detailed I'eatures and organi-
sation have been such as not only to serve the purposes of the
358 THE WORLD OF LIFE
whole series of living things, but also in their final outcome,
to serve the purposes and add to the enjoyments of man, is
highly distasteful to a large proportion of scientific workers.
They think, and some of them say, that it is a return to the
old superstition of special creation, that science has nothing
to do with first causes, whether in the form of spiritual or
divine agencies, and that once we begin to call in the aid of
such non-natural and altogether hypothetical powers we may
as well give up science altogether. In my early life I should
have adopted these same arguments as entirely valid, and
should perhaps have thought of the advocates of my present
views with the same contemptuous pity which they now be-
stow upon myself. But, I venture to urge, the cases are not
fairly comparable, because both their point of view and my
own are very different from those of our fellow-workers of the
first half of the nineteenth century.
Let me recall the conditions that prevailed then as compared
with those of to-day. Then the opposition was between science
and religion, or, perhaps more correctly, between the enthusias-
tic students of the facts and theories of physical science in the
full tide of its efforts to penetrate the inmost secrets of nature,
and the more or less ignorant adherents of dogmatic theology.
]N^ow, the case is wholly different. Speaking for myself I
claim to be as whole-heartedly devoted to modern science as
any of my critics. I am as fully imbued with the teachings
of evolution as they can be ; and I still uphold, as I have al-
ways done, the essential teachings of Darwinism.
Darwin always admitted, and even urged, that " Xatural
Selection has been the most important but not the exclusive
means of modification." He always adduced the " laws of
Growth with Reproduction," and of " Inheritance with Varia-
bility," as being fundamental facts of nature, without which
Natural Selection would be powerless or even non-existent,
and which, then as now, were and are wholly beyond explana-
tion or even comprehension. He elaborated his theory of
Panagenesis for the purpose of rendering the many strange
PLAA'TS IX UELATIOX To .MAX 30t)
facts of inheritance mure nninti'lligil)lc, l)ut cvon if it were
IJroved to be an exact representation of the facts it would not
be an explanation, because, as Weismann, Kcrncr and
many others admit, it wuiild n(jt account fur ilic forces,
the directive agency, and the orijunisiixf jx^wer wliich arc es-
sential features of growth. This is felt so strongly bv all tiie
great workers in pliysiology, that even Ilaeckel has Ix-en driven
to postulate " mind, soul, or volition," not only in every cell
but in each organic molecule or physiological on it. And then,
to save himself from the slur of being ^^ unscieniilic," an«l of
introducing the very organising power he had <l(ridcd when
suggested by others, he loudly proclaims that hi- *' soul-
atom," though it has " Avill " is yet wholly " nnc<mscious." '
I again urge, therefore, that our greatest anthorities admit
the necessity of some mind — some organising and directive
power — in nature; but they seem to contemplate merely some
unknown forces or some innate rudimentarv mind in cell or
atom. Such vague and petty suppositions, however, do not
meet the necessities of the problem. I admit that sueh forces
and such rudimentary mind-power may an<l imtbably do ex-
ist, but I maintain that they are wholly ina(h'(juate, and that
some vast intelligence, some pervading spirit i-; re(jnire<l to
guide these lower forces in accordance with a pre-ordained
system of evolution of the organic world.
If, how^ever, we go as far as this, we must go farther. If
there is a ruling and creative power to which the existence
of our cosmos is due, and if we are its one and unitpie high-
est outcome, able to understand and to make use of the forces
and products of nature in a way that no other animal lias been
able to do; and if, further, there is any reasonable probability
of a continuous life for us to still further develop that higher
spiritual nature which we possess, tlu^n W(^ have a ])erfect
right, on logical and scientific grounds, to see in all the inti-
nitely varied products of tli(> animal nn.l vegetable kingdoms,
1 The Riddle of the L'niverse. p. 04.
3 CO THE WOKLD OF LIFE
Avhich we alone can and do make use of, a preparation for
ourselves, to assist in our mental development, and to fit us
for a progressively higher state of existence as spiritual be-
ings.
CIlAl^TKK XV 11
THE MYSTERY OF THE CVAA.
I HAVE already given a short aecount of the chemical composi-
tion of protoplasm — the hii!;hly complex snhstance now ln-M
to be the physical basis of life, and by one scIkjoI of biulorrists
alleged to explain, as a resnlt of that complexity, all the won-
drous phenomena of growth and development. 1 now propose
to give a very brief sketch of the physical characteristics of the
living cell, of its internal structure, and of the extraordinary
internal changes it undergoes during the growth or reproduc-
tion of all organisms.
One of the lowest or most rudimentary forms of life is
the Amoeba, a living cell, just visible to the unaided eye as
a little speck of floating jelly. This creature, being one of
the most common of living microscopic objects, will have been
seen by most of my readers. At first, under a low microscopic
power, it appears structureless, as it was for some time de-
scribed to be, but with increasing power and perfection of the
microscope it is found to consist of three parts — a central
body of a nearly globular shape slightly darker and more
granular in texture, the outer jelly-like mass, and a small more
transparent globular portion, which looks like an air-bubble,
and is seen to undergo a slow motion of contraction and ex-
pansion; this is termed the "contractile vacuole,'' which,
when it has reached its full size, p(Thaps a quarter «»r a fifth
of the whole diameter, suddenly disappears, and after a little
while reappears and gradually grows again to it< maximum
size. The shape of the Amceba varies greatly. Sometimes it
is globular and immovable, but most fr':^quently it is very ir-
regTilar with arm-like processes jutting out in various direc-
tions. By careful watching, these are seen t-. increase or
[]G1
362 THE WORLD OF LIFE
diminish so as to change the whole shape in an hour ov two.
But more curious is its power of absorbing any particles of
organic matter that come in contact with it by gradually en-
closing them in its substance, wdiere after a time they dis-
appear. The Amoebae are found in stagnant water full of or-
ganic matter, and if they are transferred to pure waiter they
soon diminish in size, proving that they require food and can
digest it. The '' contractile vacuole " is believed to have the
function of expelling the carbonic acid gas and other waste
products of assimilation.
This Amoeba is one of the simplest forms of the lowest
branch of the animal kingdom, the one-celled animals or
Protozoa ; all other animals being classed as Metazoa, as they
are entirely built up of separate cells, which in all the more
complex forms are countless millions in number. Every part
of our bodies, from blood to muscles and nerves, from bones
to skin, hair, and nails, is alike constructed of variously modi-
fied cells.
It might be thought that animals consisting of single cells
could not be very numerous or very differently organised.
Yet they are grouped into five classes, the first, Rhizopoda,
comprising not only many kinds of Amoeba?, but the beauti-
ful Foraminifera, whose exquisite shells are such favourite
microscopic objects. They are single amoeboid cells which yet
have the power either of building up shells of small inorganic
particles, or of secreting the more beautiful shells which seem
to mimic the forms of those of the higher Mollusca. The
fossils called Xummulites were Foraminifera with flat coiled
shells, forming great masses of Eocene limestone. They are
the largest of all, some equalling a half-crown in size.
Radiolaria are rhizopods having a beautiful siliceous skele-
ton, and often living in colonies. Another class, the Mastigo-
phora, have extremely varied shapes, often like sea-weed or
flowers, having long, slender, whip-like processes. These and
hundreds of other strange forms are still essentially single
cells, though often grouped together for a time, and they all
MYSTERY OF THE CELL 3G3
increase either by division or by giving off buds, which ra[)i(lly
grow into the perfect form.
The remarkable thing in all these one-celled creatures is
that they so much resemble higher animals without any of their
organs. The writer of the article Cell iu Chambers's
Encyclopaedia says: ''The absence of a circulating fluid, of
digestive glands, nerves, sense-organs, lungs, kidneys, an<l the
like, does not in any way restrict the vital functions of a
unicellular organism. All goes on as usual, only with gi-eater
chemical complexity, since all the different processes have but
a nnit-mass of protoplasm in which they occur. The physi-
ology of independent cells, instead of being very simple, must
be very complex, just because structure or differentiation is
all but absent." All the one-celled animals and plants go
through a series of changes forming the cycle of their life-
history. Beginning as a nearly globnlar quiescent cell, they
change in form, put forth growths of various kinds, then be-
come quiescent again and give rise to new cells by subdivi-
sion or budding.
This fundamental fact, that all organic life-forms begin
with a cell and are wholly built up either by outgrowths of
that one cell or by its continued division into myriads of
modified cells of which all the varied organs of living things
are exclusively formed, was first established about the year
1840, and was declared by the eminent naturalist Louis
Agassiz to be " the greatest discovery in the natural sciences
in modern times." The cell is now defined as "" a nucleated
unit-mass of living protoplasm." It is not a mere particle
of protoplasm, but is an organised structure. We are again
compelled to ask, Organised by what? Huxley, as we have
seen in Chapter XV., tells us that life is the organising power ;
Kerner termed it a vital force ; Haeckel, a cell-soul, but un-
conscious, and he postulated a similar soul in each organic
molecule, and even in each atom of matter. But none of these
verbal suggestions go to the root of the matter; none of thcui
suppose more than some ^' force," and force is a cause of
366 THE WOKLD OF LIFE
cell-substance. This serves to divide the chromatin elements into
two equal parts, to separate the resulting halves from one another,
and to arrange them in a regular manner. At the opposite poles
of the longitudinal axis of the nucleus two clear bodies — the
*' centrosomes/" each surrounded by a clear zone — the so-called
'' sphere of attraction '^ — now becomes visible (A to D, cs). They
possess a great power of attraction over the vital particles of the
cell, so that these become arranged around them in a series of
rays. At a certain stage in the preparation for division, the soft
protoplasmic substance of the cell-body as well as of the nucleus
gives rise to delicate fibres or threads ; these fibres are motile, and,
after the disappearance of the nuclear membrane, seize the chromo-
somes — whether these have the form of loops, rods, or globular
bodies — with wonderful certainty and regularity, and in such a
way that each element is held on either side by several threads from
either pole (B, C). The chromatin elements thus immediately be-
come arranged in a fixed and regular manner, so that they all come
to lie in the equatorial plane of the nucleus, which we may con-
sider as a spherical body."
!N^ow follows another and even more remarkable stage in
the process, which is thus described :
" The chromatin elements then split longitudinally, and thus
become doubled (B), as Fleming first pointed out. It must be
mentioned that this splitting is not caused by a pull from the pole
threads (spindle threads), which attach themselves to the chroma-
tin-rods on both sides ; the division arises rather from forces acting
in the rods themselves, as is proved by the fact that they are often
ready to divide, or indeed have already done so, some time before
their equatorial arrangement has taken place by means of these
threads.
" The splitting is completed by the two halves being gradually
drawn further apart towards the opposite poles of the nuclear
spindle, until they finally approach the centre of attraction or
centrosome (D), which has now fulfilled its object for the present,
and retires into the obscuritv of the cell-substance, onlv to become
active again at the next cell-division. Each separated half of the
nucleus now constitutes a daughter-nucleus, in which it (the
MYSTERY OF THE CELL 367
chromatin) immediately breaks up, and Ixvomps scattered in the
form of minute granules in tlic delicate nuclear network, so that
finally a nucleus is formed of exactly the same structure as that
with which we started."
Weismann then discusses and explains the meaning of this
strange phenomenon. He says:
" It is evident, as Wilhelm Koux was the first to point out, that
the whole complex, but wonderfully exact, apparatus for the division
of the nucleus exists for the purpose of dividing the chromatin
substance in a fixed and regular manner, not merely quantitatively,
but also in i-espect of the different qualities which must be contained
in it. So complicated an apparatus wouhl have been unnecessary
for the quantitative division only. W, however, the chromatin sub-
stance is not uniform, but is made up of several or many different
qualities, each of which has to be divided as nearly as possible into
halves, or according to some definite rule, a better apparatus could
not be devised for the purpose. On the strength of this argument
we may, therefore, represent the hereditary substance as consisting
of different qualities. . . . The statement that this substance
is the hereditary substance can, therefore, hardly be considered as
an hypothesis any longer." ^
After some further discussion of the views of other writers,
he goes on to show that the chromatin substance is not only
contained in the germ-cells, but also in all the cells of the
entire organism in each phase of its development, which is
effected bv the constant division of the cells and their nuclei,
the chromatin continuing to grow during the whole time. But
in the body it enters on a long and complex process of growth,
so as to build up the substance of all the varied organs and
tissues, and also for the repair or renovation of these various
tissues as they require it. He illustrates the successive
changes which he supposes the chromatin to bring about, and
for which purpose it is so accurately divided and subdivided
from the very beginning, in the following inissage:
1 The Gcnn-Plasm, p. 29.
368 THE WORLD OF LIFE
"Even the two first clanghter-cells (E) which result from the
division of the egg-cell give rise in many animals to totally different
parts. One of them, by continued cell-division, forms the outer
germinal layer, and eventually all the organs which arise from it,
e. g. the epidermis, central nervous system, and sensory cells ; the
other gives rise to the inner germinal layer and the organs derived
from it — the alimentary system, certain glands, etc. The conclu-
sion is inevitable that the chromatin determining these hereditary
tendencies is different in the very first two daughter-cells."
Later on he shows in great detail how^ similar but even
more complex changes take place in the newly fertilised germ-
cell in v^hich the male and female elements are combined, for
the purpose of bringing about the accurate partition of these
elements in all the cells which arise from them by subdivision,
thus rendering possible the production, in all future genera-
tions, of males and females in nearly equal proportions. He
also shows that there is a special provision for the produc-
tion of slight variations in successive generations in a way too
complex to be explained here. This, of course, is largely
speculation, but it is based at every step on observed facts
in the processes of fertilisation and cell-division.^
In Professor J. Arthur Thomson's most valuable and il-
luminating work on Heredity, in which he impartially ex-
pounds the theories and discoveries of all the great physio-
logical writers of the world, he gives a very high, if not the
highest, place to those of Weismann. I will therefore quote
from his volume Weismann's latest short statement of his
hypothesis as to the nature of the germ-plasm ; and also Pro-
1 The reader will see that the diagrams referred to in Weisraann's state-
ments, quoted above, do not seem to represent accurately what he says.
They must, therefore, be taken as " diagrams " only, not detailed " figures "
of what is seen, which are often so complex that it is difficult to follow
the essential details. They are for the purpose of indicating definite stages
in the process of the development of cells up to the first cell-division.
The small letters (jd) are not referred to in Weismann's explanation on
the plate itself, nor in his description of what happens. But these letters
evidently mean " idants," as explained in Professor J. A. Thomson's sum-
mary of Weismann's theory at p. 20.
MYSTEP.Y OF THE CELL 309
fessor Thomson's very short summary of it, giving an explana-
tion of Weismann's special terminology. Weismann's state-
ment is as follows:
" The germ-substance owes its marvellous power of development
not only to its chemico-physical constitution, but to the fact that it
consists of many different kinds of primary constituents, that is,
of groups of vital units equipped witli the forces of life, and capa-
ble of interposing actively and in a specific manner, but also
capable of remaining latent in a passive state until they are af-
fected by a liberating stimulus, and on this account able U) inter-
pose successfully in development. The germ-cell cannot be merely
a simple organism; it must be a fabric made up of many different
organisms or units — a microcosm." ^
And Professor J. A. Thomson's Summary of Weismann's
mechanics of the germ-plasm is as follows :
Summary
" The physical basis of inheritance — the germ-plasm — is in
the chromatin of the nucleus of the germ-cell.
" The chromatin takes the form of a definite number of chromo-
somes or idants (Fig. 110, B, C, D, id).
" The chromosomes consist of ids, each of which contains a
complete inheritance.
" Each id consists of numerous primary constituents or deter-
minants.
" A determinant is usually a group of hiophors, the minutest
vital units.
" The biophor is an integrate of numerous chemical molecules."
In the preceding Summary I have italicised the technical
terms invented by Weismann for the different stages of what
may be called the mechanical explanation of heredity by
means of the successive changes observed in the growing and
dividing germ-cells. But, as he himself admits, it explains
nothing Avithout taking for granted the essential phenomena of
life — nutrition, assimilation, and growth; and these are ad-
mitted to be to this day quite unexplainable.
iThe Evolution Tlipory, trans, by J. A. Tlionison. 1004. vol. i. p. 402.
370
THE WORLD OF LIFE
chr.
^ii
ciftr
J)
Fig. 110. — Diagram of Nuclear
Division.
A. Cell with nucleus (n) and centro-
somes {cs) preparatory to division.
The chromatin has become thick-
ened so as to form a spiral thread
(c/ir).
B. The nuclear membrane has dis-
appeared. Delicate threads radiate
from the chromosomes, and form
the "nuclear spindle," and the
equator of which eight chromo-
somes or nuclear loops (chr=Jd)
are arranged; these have been
formed by the spiral thread of
chromatin in A becoming broken
up.
C. The chromosomes have each be-
come split longitudinally into two,
and are about to be drawn apart
by means of the spindle threads. (For clearness four only of the eight chromo-
somes are shown.)
D. The daughter-loops pass towards the poles of the spindle.
E. The cell has divided, each new cell containing a centrosome and eight nuclear
loops.
(From Weismann's Germ-Plasm, by permission of Walter Scott, Ltd.)
MYSTERY OF THE CELJ. 371
But the very first step of this process of ^^rowtli — the di-
vision of the germ-cells, as descrihed by Weisniann himself
and illustrated by his diagrams — is, as he himself almost ad-
mits, equally inexplicable. He speaks of a *' complex, but
wonderfully exact, apparatus for the division of the nucleus,"
of the purpose of that division being qualitative as well as
quantitative, and of its evident adnptailon to the building up
of the future body, with all its marvellous complexities, co-
ordinations, and powers. So that the farther we go in this
bewildering labyrinth, as expounded in his wnrlcs, in those of
Professor Thomson, of Max ^^erworu, or in such general works
as Parker and Haswell's Text-Book of Zoology, the more hope-
lessly inadequate do we find the claims of Ilaeckel, Verworu,
and their school to having made any approach whatever to a
solution of " the riddle of the universe,'' so far as regards its
crowning problem, the origin and development of life.
The Plant Cell
So far I have taken the facts as to cell-division from the
works of zoologists only ; but almost exactly the same phe-
nomena have been found to occur in plants, though they seem
to have been rather more difficult to detect and unravel. In
Professor A. Kerner's Katural History of Plants, already
quoted, he gives the following short description of cell-di-
vision :
Wlien a protoplast living in a cell-cavity is about to divide into
two, the process resulting in division is as follows : — The nucleus
places itself in the middle of its cell, and at first characteristic lines
and streaks appear in its substance, making it look like a ball made
up of little threads and rods pressed together. Tliese threads
gradually arrange themselves in positions corresponding to the
meridian lines upon a globe: but at the place where on a globe
the equator would lie, there then occurs suddenly a cleavage of tlie
nucleus — a partition wall of cellulose is interposed in the gap. and
from a single cell we have now produced a pnir of cells ■' (vol. i.
p. 48).
372 THE WOELD OF LIFE
But later on we have a much fuller description, illustrated
by four diagrammatic figures of the dividing cell, which show
that the process in plants is substantially identical with that
described and figured already from Weismann (vol. i. p.
581). This is most instructive, because it shows the absolute
identity of the fundamental mechanics of life in the animal
and vegetable kingdoms, though their ultimate developments
are so wonderfully diverse.
Another interesting point is that, just as Weismann has
stated, there is an identity in the number of certain elements
in the cell for each species. Kemer's statement is :
" For every species of plant the number, size, and shape of the
bodies arising in the interior of a cell by division are quite definite,
though they vary from species to species. In the cell-chambers of
some species several thousand minute protoplasmic bodies arise.
In others, again, the number is very limited. If the number is
large the individual masses are exceedingly small, and can only be
recognised when very greatly magnified. If the number is limited
the divided portions are comparatively large. The shape of the
structure is exceedingly various. Some are spherical, elliptical, or
pear-shaped; others elongated, fusiform, filamentous, or spatulate;
some are straight, others are spirally twisted, and many are drawn
out into a thread; others are provided over the whole surface with
short cilia; others, again, with a crown of cilia at a particular
spot, or with only a single pair of long cilia. In the majority of
cases the small bodies exhibit active movements; but sooner or
later they come to rest, and then assume another shape or fuse
with another protoplasmic body."
Referring to the theory that the structure of each plant
is due to the specific constitution of the protoplasm of the
species, Kerner says :
" What it does not account for is the appropriate manner in
which various functions are distributed among the protoplasts of
a cell-community ; nor does it explain the purposeful sequence of
diiferent operations in the same protoplasm without any change
in the external stimuli; the thorough use made of external ad-
MYSTERY OF THE CELL 37U
vantages; the resistance to injurious influences; the avoidance or
encompassing of insuperable obstacles ; the punctuality with which
aU the functions are performed ; the periodicity which occurs with
the greatest regularity under constant conditions of environment ;
nor, above all, the fact that the power of discharging all the op-
erations requisite for growth, nutrition, renovation, and multipli-
cation is liable to be lost. We call the loss of this power the death
of the protoplasm" (vol. i. p. 51).
Growth hy Cell-Division: What it Implies
As the account now given of the most recent discoveries as
to what actually takes place in the living cell preparatory to
its division and subdivision, wliich are *\ 3 very first steps in
the growth or building up of the highly complex 'and perfect
animal or plant, is very technical, and will be perhaps unin-
telligible to some of my readers, I will now give a very short
statement of the process with a few illustrations, and remarks
as to w^hat it all really means, and how" alone, in my opinion,
it can possibly be explained.
The egg is a single cell with a special central point or organ,
called the nucleus, and it is this nucleus which makes the cell
a germ-cell. That this is so has been proved in many ways, —
in plants by grafting or hudding, where the ilower-bud which
contains a germ-cell, when inserted in the bark of a differ-
ent variety, and sometimes a different species of plant, repro-
duces the exact kind of flower or fruit that characterised the
tree or bush the bud was taken from, not that of the plant of
which it now^ forms a part, and whose sap forms its nourish-
ment.
Again, Professor Boveri deprived an Qgg of a species of
sea-urchin {Echinus microtuherculatus) of its nucleus, and
then fertilised the egg with the spermatozoa of anotlier species
{Sphcerechiiiu^ qranidaris). The egg so treated developed
larva? with the true characters of the latter species only, so
that the main substance of the egg provided nutriment for
the offspring, but did not transmit to it any of it^ parental
a7i THE WOELD OF LIFE
characters. A similar illustration, at a later period of life, is
that of an infant Avhich from birth is fed on cow's milk, yet,
if it lives, possesses only human characteristics.
This nucleus^, therefore, which, when fertilised, has such
marvellous powers and properties, is tlie seat of heredity and
development. What is it that gives it this power ? What
is the agency that sets in motion a whole series of mechanical,
chemical, and vital forces, and guides them at every step to
their destined end ? Again, I urge, let us consider what we
have to explain. The matter of the fertilised egg is the mil-
lionfold complex substance called protoplasm. It is also
mainly living protoplasm. AVhat power gave it life ? It is
also (in its essential part, the nucleus) already highly differ-
entiated — it is organised 'protoplasm. What poiver organ-
ised it ? It is a liquid or semi-liquid substance with slight
cohesion ; it gradually forms a cell, which divides and sub-
divides, till at a certain point the globular mass or layer of cells
bends inward upon itself, forming a hollow sac with outer and
inner walls. What power determines the cell-mass to take
this or other well-defined shapes ? Then, as cell-division and
specialisation go on, the rudiments of muscle and bone are
formed with totally distinct properties — the one with im-
mense contractility and tensile strength, the other with great
hardness and rigidity. Who or what guides or determines
the atoms of the protoplasmic molecules into these new comibi-
nations chemically, and new structures mechanically ? — com-
binations and structures which all the chemists and physicists
of the world are powerless to produce even when they have the
ready-formed protoplasm given them to start with ? Then as
the process goes on in an ever-increasing complexity which
baffles the microscope of the observer to follow, never diverg-
ing at any one point from the precise mode of change which
alone leads on to the completed living organism, we are asked
to be satisfied with millions of ^^ gemmules," " fundamental
units," " determinants," etc., which actually do build up the
MYSTEKY OF THE CELL 375
living body of each organism in a prescribed and lUK-liangcable
sequence of events. But this orderly process is quite unintel-
ligible without some directive org,anising power constantly at
work in or upon every chemical atom or physical niolcculv of
the whole structure, as one after another they are brought to
their places, and built in, as it were, to the structure of every
tissue of every organ as it takes form and substance in tlie
fabric of the living, moving, and, in the case of animals, sensi-
tive creation.
I will conclude this short sketch of cell-life and its mystery,
with a picturesque account of one striking example in the ani-
mal world, from Professor Lloyd Morgan's illuminating vol-
ume.
There is, perhaps, no more wonderful instance of rapid and
vigorous growth than the formation of the antlers of deer. These
splendid weapons and adornments are shed every year, in the
spring, when they are growing, they are covered over with a dark
skin provided with short, line, thick-set hair, and technically termed
" the velvet.'^ If you lay your hand on the growing antler, you will
feel that it is hot with the nutrient blood that is coursing beneath
it. It is, too, exceedingly sensitive and tender. An army of tens
of thousands of busv livinor cells is at work beneath that velvet
surface, building the bony antlers, preparing for the battles of
autunm. Each minute cell knows its work, and does it for llie
general good — so perfectly is the body knit into an organic whole.
It takes up from the nutrient blood the special materials it requires ;
out of them it elaborates the crude bone-stuff, at first soft as wax,
but ere long to become as hard as stone; and then, having done iis
work, having added its special morsel to the fabric of the antler, it
remains imbedded and immured, buried beneath the bone prodiRis
o": its successors or descendants. No hive of Ijccs is busier or more
replete with active life than the antler of a stag as it grows ])eneatli
the soft warm ' elvet. And thus are built up in the eoiirsp of a few
weeks those splendid "beams" with their " tynos '' and "snags,"
which, in the case of the wapiti, even in the continomont of the
Zoological Gardens, may reach a weight of thirty-two ]>ounds, and
376 THE WOKLD OF LIFE
which, in the freedom of the Eocky Mountains, may reach such a
size that a man may walk without stooping through the archway
made by setting up upon their points tlie shed antlers.
In the eastern European forests the horns of the red deer
reach a w^eight of 74 pounds, while in the recently extinct Irish
elk the large, broadly palmated horns sometimes reached an
expanse of 11 feet. These remarkable weapons were devel-
I oped both for combats between the males and as a means of pro-
\ tecting the females and young from enemies. As organic out-
growths they are extremely simple when compared with the
feathers of the bird or the scales of a butterfly's wing; yet as
exemplifying the need for some guiding power, exerted upon
the individual cells which carrv out the work with such won-
derful precision every year, they are equally striking. The
blood, we know, furnishes the materials for every tissue in the
body; but here a large mass of bony matter, covered with a
thin skin and dense hair, is rapidly built up, to a very definite
form in each species; then the skin and hair cease growing
and fall away, while the horns persist for nearly a year, when
they, too, fall off and are again renewed.
Concluding Remarks on the Cell-Prohlem
The very short account I have now given of w^hat is known
of the essential nature, the complex structure, and the alto-
gether incomprehensible energies of these minute unit-masses
of living matter, the cells — so far as possible in the very words
of some of the most recent authorities — must, I think, con-
vince the reader that the persistent attempts made by llaeckel
and Yerw^oru to minimise their marvellous powers as mere re-
sults of their complex chemical constitution, are w^holly un-
availing. They are mere verbal assertions which prove noth-
ing; w^hile they afford no enlightenment wdiatever as to the
actual causes at work in the cells leading to nutrition, to growth,
and to reproduction.
Very few of the workers who have made known to us the
MYSTEKY OF THE CELL 377
strange phenomena of cell-life in liie Protozoa, and of cell-
division in the higher animals and plants, seem to think any-
thing about the hidden causes and forces at work. They are
so intensely interested in their discoveries, and in following
out the various chani^es in all their ramitications, that tliev
have no time and little inclination to do more than add con-
tinually to their knowledge of the facts. And if one attempts
to read through anv ffood text-book such as Parker and Has-
well's Zoology, or J. Arthur Thomson's Heredity, it is easy to
understand this. The complexities of the lower forms of life
are so overwhelming and their life-histories so mysterious, and
yet they have so much in common, and so many cross-affinities
among the innumerable new or rare species continually being
discovered, that life is not long enough to investigate the struc-
ture of more than a very small number of the known forms.
Hence very few of the writers of such books express any opin-
ion on those fundamental problems which Haeckel and his fol-
low^ers declare to have been solved by them. All questions of
antecedent purpose, of design in the course of development, or
of any organising, directive, or creative mind as the funda-
mental cause of life and organisation, are altogether ignored,
or, if referred to, are usually discussed as altogether imscien-
tific and as showing a deplorable want of confidence in the
powers of the human mind to solve all terrestrial problems.
If, as I have attempted to do here, we take a broad and com-
prehensive view of the vast world of life as it is spread out be-
fore us, and also of that earlier world which goes back, and
ever further back, into the dim past among the relics of pre-
ceding forms of life, tracing all living things to more gen-
eralised and usually smaller forms; still going back, till one
after another of existing families, orders, and even classes, of
animals and plants either cease to appear ur are represented
only by rudimentary forms, often of types tpiite unknown to
us; we meet with ever greater and greater ditiiculties in dis-
pensing with a guiding purpose and an immanent creative
powder.
378 THE WOKLD OF LIFE
For we are necessarily led back at last to the beginnings of
life — to that almost infinitely remote epoch myriads of years
before the earliest forms of life we are acquainted with had
left their fragmentary remains in the rocks. Then, at some
definite epoch, the rudiments of life must have appeared. But
whenever it began, whenever the first vegetable cell began its
course of division and variation ; and when, very soon after,
the animal cell first appeared to feed upon it and be developed
at its exj)ense, — from that remote epoch, through all the ages
till our own day, a continuous, never-ceasing, ever-varying
process has been at work in the two great kingdoms, vegetal
and animal, side by side, and always in close and perfect
adaptation to each other.
Myriads of strange forms have appeared, have given birth
to a variety of species, have reached a maximum of size, and
have then dwindled and died out, giving way to higher and
better-adapted creatures ; but never has there been a complete
break, never a total destruction, even of terrestrial forms of
life ; but ever and ever they became more numerous, more varied,
more beautiful, and hetler adapted to tJie wants, the 'material
'progresSj, the higher enjoyments of mankind.
The whole vast series of species of plants and animals, with
all their diversities of form and structure, began at the very
dawn of life upon the cooling earth with a single cell (or with
myriads of cells) such as those whose structure and properties
we have here been considering; and every single individual of
the myriads of millions Avhich have ever lived upon the earth
have each begun to be developed from a similar but not idm-
tical cell ; and all the possibilities of all their organs, and
structures, and secretions, and organic products have arisen out
of such cells; and we are asked to believe that tliese cells and
all their maiwellous outcome are the result of the fortuitous
clash of atoms with the help of '^ an unconscious cell-soul of
the most primitive and rudimentary kind ! "
MYISTEKV OF THE CELL 3Tti
The Fallacy of Eternity as an Explanation of Evolution
It may perhaps not be out of place here to deal with what
seems to me to be one of the common philosophical fallacies of
the present day, the iilea that you can get over the difficulty
of requiring any supreme mind, any author <jf the cosmos, by
assuming that it had no beginning — that it has existed, with
all its forces, energies, and laws, from all eternity, and thai it
^vill continue, to exist for all eternity.
I have already quoted llaeckel and some others on this
point. I will now give a similar statement by two writers of
to-day. Dr. Saleeby in an article on The Life of the Uni-
verse, in The Academy (March 25, 1905), after discussing
the theory of dissipation of energy, the infinity of the uui-
verse, the littleness of man, and other matters, with his usual
clearness and vigour, concludes with this sentence : '' Radium-
clocks have been made that will go for a million years ; but I
believe that the Universe was never made and will go on for
ever." This, of course, is vague, because, if the term "' uni-
verse '' is taken to mean " the all that exists," or rather, '' all
that exists, that ever has existed, or that ever will exist,'' it is
a truism, because that includes all life and God. But " uni-
verse " is taken bv llaeckel and his school to mean the ma-
terial universe, and to definitely exclude spirit and god.
A great modern physicist. Professor Svanto Arrhenius, in
the preface to his recent work. Worlds in the ^Making, con-
cludes thus:
"My guiding principles in this exposition of cosinogonic pi-(.h-
lems has been the conviction that the Universe in its csseiico luis
always been what it is now. Matter, energy, and life iiavo only
varied as to shape and position in space."
This will be taken to mean, and T presume does mean,
"matter" and "life" as we know them on the earth, and to
exclude, as Haeckol does drfinitely, spirit and deity. The
general conception of all these writers seems to be, that it is
380 THE WORLD OF LIFE
easier, simpler, more scientific, to assume that '^ matter,
energy, and life " as we see them, have existed, the same in
essence though in ever varying forms, from all eternity, and
will continue to exist to all eternity, than to assume any intel-
ligent power beyond what we see.
Xow the idea, that positing eternity for matter and for or-
ganised life, and for all the forces of nature, overcomes diffi-
culties or renders their existence at the stage they have now
reached at all intelligible, is, I maintain, the very opposite of
the truth, and arises from a want of real thought as to what
" eternity " means. Take, first, " life " culminating in
" man." It is admitted that there has been a continuous
though not uniform progress from the first organic cell up to
man. To arrive at that end it has admittedly occupied a very
large portion of the duration of the habitability of the planet,
and of the sun as a heat and life-giver. It is also assumed
that, to ensure the persistence of life w^hen suns cool and planets
are unsuitable, either the germs of life must be carried through
space (at the zero of temperature) from one solar system to
another till they chance to alight upon one where the condi-
tions of life are suitable, or they must have developed again
out of dead matter. All this is overwhelmingly difficult, — but
let us grant it all. Let us grant also that there are forces and
energies capable of automatically building up progressively
developing forms of sentient life, such as have been built up
on the earth. Then, if these forces and energies have acted
from all eternity, they must have resulted in an infinite life-
development, that is, in beings inconceivably higher than we
are. Now we, who, as they all tell us, are poor miserable
creatures of a day, have yet got to know much of the universe,
to apply its forces, and thus to modify nature — so, an eternity
of progress at the same rate (and as there is progress there is
no cause why it should stop) must necessarily have produced an
infinite result — that is, beings which as compared with us
Avould be gods. And as you cannot diminish eternity, then
MYSTERY OF THE CELL 381
long ages before the first rudiment of life appeared npon the
earth, long before all the suns we see had l>eeonie suns, the in-
finite development had been at work and must liavc ])r(>diic(Ml
gods of infinite degrees of powei-, any one of whom would pre-
sumably be quite capable of starting such a solar system as
ours, or one immensely larger and better, and of so determin-
ing the material constitution of an " earth " as to initiate and
guide a course of development which would have resulted in
a far higher being than man. Once assume a mind-developing
power from all eternity, and it must, noiu, and at all earlier
periods of the past have resulted in beings of infinite power —
what we should term — Gods !
It may, I think, be stated generally, that whatever has an
inherent power of increase or decrease, of growth, develop-
ment, or evolution, cannot possibly have existed from a past
" eternity '' unless the law of its evolution is an ever-recurrent
identical cycle, in which case, of course, it may, conceivably,
have existed from eternity and continue through an eternity of
future cycles, all identical; and, therefore, such cycles could
never produce anything that had not been produced an in-
finite number of times before. Is this a satisfactory outcome
for an eternal self-existent universe ? Is this easier, simpler,
more rational, more scientific, more philosophical, than to
posit one supreme mind as self-existent and eternal, of which
our universe and all universes are the manifestations I And
yet the " infinity and eternity " men call themselves ^' monists,'^
and claim to be the only logical and scientific thinkers. With
them matter, ether, life — (surely three absolutely distinct
things) — with all the wonderful laws, and forces, and direc-
tive agencies which they imply, and without which none of
them could for a moment exist, all are to be accounted for and
explained by the one illogical assumption, their eternity ; the
one complete misnomer, monism ; the one alleged fundamental
law which explains nothing, the " law of substance."
It will be seen that this alleged explanation — the eternal
material universe — does not touch the necessitv, becominc:
382 THE WORLD OF LIFE
more clear every day, not for blind laws and forces, but for
immanent directive and organising mind, acting on and in
every living cell of every living organism, during every moment
of its existence. I think 1 have sufficient! v shown that with-
ont this, life, as we know it, is altogether unthinkable. Xo
^^ eternal " existence of matter will make this in the remotest
defifree imaginable. It is this difficultv which the ^^ monists ''
and the " eternalists " of the Llaeckel and Verworu type abso-
lutely shirk, putting us off ^vith the wildest and most contra-
dictory assertions as to what they have proved !
I venture to hope and to believe that such of my readers
as have accompanied me so far through the present volume,
and have had their memory refreshed as to the countless
marvels of the world of life ; culminating in the two great
mysteries — that of the human intellect wdth all its powers
and capacities as its outcome, that of the organic cell with
all its complexity of structure and of hidden powers as its
earliest traceable origin — will not accept the loud assertion,
that everything exists because it is eternal as a sufficient or a
convincing explanation. A critical examination of the sub-
ject demonstrates, as the greatest metaphysicians agree, that
everything but the Absolute and Unconditioned must have had
a beginning.
CHAPTER XVIII
THE ELEMENTS AND WATER, IN RELATION TO THE LIFE-WORLD
I HAVE already (in Chapter XVI.) given the statements of
two continental physiologists as to great chemical complexity
of the proteid molecule, involving as it does, in certain cases
already studied, a combination of about two thousand chemical
atoms. A more recent authority (Mr. W. Bate Hardy) is of
opinion that this molecule really contains about thirty thou-
sand atoms, while the most complex molecule known to the
organic chemist is said to contain less than a hundred. One
of the results of this extreme complexity is that almost all the
products of the vegetable and animal kingdoms are what are
termed hydro-carbons, that is, they consist of compounds of
carbon, with hydrogen, oxygen, or nitrogen, or any or all of
them, combined in an almost infinite variety of ways. Yet
the compounds of these four elements already known are more
numerous than those produced by all the other elements, more
than seventy in number.
This abundance is largely due to the fact that the very same
combination of carbon with the three gaseous constituents of
the carbon-compounds often produces several substances very
different in appearance and properties. Thus dextrine (or
British gum), starch, and cellulose (the constituents of the
fibres of plants) all consist of six atoms of carbon, ton of
hydrogen, and five of oxygen ; yet they have very different
properties, cellulose being insoluble in water, alcohol, or ether ;
dextrine soluble in water but not in alcohol ; while starch is only
soluble in Avarm water. These differences are supposed to be
due to the different arrangement of the atoms, and to their being
combined and recombinod in dift'orent ways; and as the more
atoms are used, the possible complexity of these arrangements
383
384 THE WORLD OF LIFE
becomes greater, and the vast numbers and marvellous diversity
of the organic compounds becomes to some extent intelligible.
Professor Kerner, referring to the three substances just men-
tioned, gives the following suggestive illustration of their
diverse properties, of which I have only mentioned a few. He
says :
" If six black, ten blue, and five red balls are placed close to-
gether in a frame, they can be grouped in the most diverse ways
into beautiful symmetrical figures. They are always the same
balls, they always take up the same space, and yet the effect of the
figures produced by the different arrangements is wholly distinct.
It may be imagined, similarly, that the appearance of the whole
mass of a carbon-compound becomes different in consequence of
the arrangement of the atoms, and that not only the appearance
but even the physical properties undergo striking alterations."
Another and perhaps more interesting example, illustrated
by a diagram, is given by Mr. W. Bate Hardy in his lecture
already referred to. He says :
" Here is a simple and startling case. The molecules of two
chemical substances, benzonitrile and phenylisocyanide, are com-
posed of seven atoms of carbon, five of hydrogen, and one of
nitrogen :
N C
H— C I 1 C— H H— C I I C— H
H— C I I C— H H— C I I C— H
c c
Benzonitrile. Phenylisocyanide.
The only difference in the arrangement of the atoms is that those
of nitrogen and carbon are reversed. But the properties of these
two substances are as unlike as possible. The first is a harmless
fluid with an aromatic smell of bitter almonds. The second is
very poisonous, and its odour most offensive."
THE ELEMENTS AXl) LIFE 385
Here only three elements are combined, and in identical pro-
portions. We can imagine, therefore, what endless diversities
arise when to these are added anv of nine other elements, and
these in varying proportions, as Avell as being groii])ed in every
possible manner.
The fact of ^^ isomerism," or of different substances, often
with very different properties, having the very same chemical
composition, is now so familiar to chemists as to excite com-
paratively little attention, yet it is really a marvel and a mys-
tery almost equal to that of the organic cell itself. It is
probably dependent upon the highly complex nature of the
molecules of the elements, and also of the atoms of which these
molecules are built up; while atoms themselves are now be-
lieved to be complex systems of electrons, which are held to be
the units of electricity and of matter. It is these electrons
and their mysterious forces that give to matter all its mechan-
ical, physical, and chemical properties, including those which,
in the highly complex protoplasm, have rendered possible that
whole world of life we have been considering in the present
volume.
Here, then, we find, as before, that the further back we go
towards the innermost nature of matter, of life, or of mind,
we meet with new complications, new forces, new agencies, all
pointing in one direction towards the final outcome — the buikl-
ing up of a living sentient form, which should be the means
of development of the enduring spirit of man.
Important and Unimportant Elements
If we look at the long list of between seventy and eighty
elements now known we shall see that a comparatively suuill
number of these (less than one-fourth) seem to play any im-
portant part either in the structure of the earth as a phinet,
or in the constitution of the organised l)eings that have been
developed upon it. The most important of the elements is
oxygen, which is not only an essential in the structure of all
living things, but forms a large part of the air and the water
386 THE WORLD OF LIFE
which are essential to their contiiiTied existence. It is also a
constituent of almost every mineral and rock, and is estimated
to form about 47 per cent of the whole mass of the globe. The
next most abundant elements are silicon, aluminium, and iron,
which form 25, 8, and 7 per cent respectively of the earth-
mass. Then follow calcium, magnesium, sodium, and potas-
sium, contributing from about 4 to 2 per cent of the whole;
while no other element forms so much as one per cent, and the
majority probably not more than one-fiftieth or one-hundredth
of one per cent.
The gases, hydrogen and nitrogen, are, however, exceedingly
important as forming with oxygen the atmosphere and the
oceans of the globe, which by their purely physical action on
climate, and in causing perpetual changes on the earth's sur-
face, have rendered the development of the organic w^orld pos-
sible. These ten elements appear to be all that were necessary
to constitute the earth as a planet, and to bring about its varied
surface of mountain and valley, rivers and seas, volcanoes and
glaciers ; but in order to develop life, and thus clothe the earth
with ever-growing richness of vegetation and ever-changing
forms of animals to be sustained by that vegetation, four other
elements were required — carbon, sulphur, phosphorus, and
chlorine — but these being either gaseous or of very small spe-
cific gravity, and thus existing (perhaps exclusively) near the
earth's surface, comparatively little of them was needed.
Elements in Protoplasm in Order of their
Abundance {approximately).
1.
Hydrogen
2.
Carl) 011
3.
Oxvgen
4.
Nitrogen
5.
Sulphur
6.
Iron
Phosphorus
8.
Chlorine
9.
Sodium
10.
Potassium
11.
Calcium
12.
Magnesium
List of the More Important Elements
Elements in the Earth in Order of their
Quantity {approximately).
per cent.
1. Oxygen 47
2. Silicon 25
3. Aluminium 8
4. Iron 7
5. Calcium 4
6. Magnesium 3
7. Sodium 2.5
8. Potassium 2.5
9. Hydrogen (?) 0.1
10. Nitrogen (?) 0.1
All others (?) 0.8
100
THE ELEME:N^TS AXD life 387
The two elements in italics — iiilicoit and Alumijiiuni — altlioiii:li form-
ing a large proportion of the earth's substance, are not ctmcndal constitu-
ents of protophism, although occasionally forming part of it.
In the list of the more important elements here given, I
have arranged them in two series, the first showing the essential
constituents of protoplasm ; the second showing the ten which
are the most important constituents of the earth's mass as
known to geologists and physicists. The four which are itali-
cised in the first list do not appear in the second, and cannot,
therefore, be considered as forming an essential portion of the
rock-structure of the earth, although without them it seems
fairly certain that the life-world could not have existed.
The Elements in relation to Man
So far as we can see, therefore, the fourteen elements in
these two lists would have sufficed to brine: about all the essen-
tial features of our earth as w^e now find it. All the others
(more than sixty) seem to be surplusage, many exceedingly
rare, and none forming more than a minute fraction of the
mass of the earth or its atmosphere. All except seven of these
are metals, including (with iron) the seven metals known to
the ancients and even to some prehistoric races. The seven
ancient metals are gold, silver, copper, iron, tin, lead, and mer-
cury. All of these are widely distributed in the rocks. They
are most of them found occasionally in a pure state, and are
also obtained from their ores without much difficulty, which
has led to their being utilised from very early times. But
though these metals (except iron) appear to serve no important
purpose either in the earth itself or in tlie vegetable or animal
kingdoms, they have yet been of very gTcat importance in the
history of man and the development of civilisation. From very
remote times gold and silver have been prized for their extreme
beauty and comparative rarity; the search after them has led
to the intercourse between various races and peoples, and to
the establishment of a world-wide conmierce ; wliile the facility
W'ith wdiich they could be worked and polished called fortli the
388 THE WORLD OF LIFE
highest powers of the artist and craftsman in the making of
ornaments, coins, drinking-vessels, etc., many of which have
come down to ns from early times, sometimes showing a beauty
of design which has never been surpassed. Our own earliest
rudiments of civilisation were probably acquired from the
Phoenicians, who regularly came to Cornwall and our southern
coasts to purchase tin.
Each of the seven metals (and a few others now in com-
mon use) has very special qualities which renders it useful for
certain purposes, and these have so entered into our daily life
that it is difficult to conceive how we should do without them.
Without iron and copper an effective steam-engine could not
have been constructed, our whole vast system of machinery
could never have come into existence, and a totallv distinct
form of civilisation would have developed — perhaps more on
the lines of that of China and Japan. Is it, we may ask, a
pure accident that these metals, with their special physical
qualities which render them so useful to us, should have ex-
isted on the earth for so many millions of years for no appar-
ent or possible use ; but becoming so supremely useful when
Man appeared and began to rise tow^ards civilisation ?
But an even more striking case is that of the substances
which in certain combinations produce glass. Sir Henry Ros-
coe states that silicates of the alkali metals, sodium and potas-
sium, are soluble in water and are non-crystalline ; those of
the alkaline earths, calcium, etc., are soluble in acid and are
crystalline; but by combining these silicates of sodium and
calcium, or of potassium and calcium, the result is a substance
which is noi soluble either in water or acids, and which, when
fused forms glass, a perfectly transparent solid, not crystallised
but easily cut and ]3olished, elastic within limits, and when
softened by heat capable of being moulded or twisted into an
endless variety of forms. It can also be coloured in an infinite
variety of tints, while hardly diminishing its transparency.
The value of cheap glass for windows in cold or changeable
climates cannot be over-estimated. Without its use in bottles,
THE ELEMENTS AXD LIEE 389
tubes, etc., chemistry could hardly exist ; while astronomy could
not have advanced beyond the stage to which it had Itecn
brought by Copernicus, Tycho Brahe, and Kepler. It rfu-
dered possible the microscope, the telescope, and the si)ectro-
scope, three instruments without which neither the starry heav-
ens nor the myriads of life-forms would have had their inner
mysteries laid open to us.
One more example of a recent discovery of one of the rarest
substances in nature — radium — and its extraordinarv effects,
points in the same direction. So far as known at present, this
substance may or may not be in any way important either
to the earth as a planet or for the development of life upon
it ; but the most obvious result of its discovery seems to bo
the new light it throws on the nature of matter, on the con-
stitution of the atom, and perhaps also on the mysterious ether.
It has come at the close of a century of wonderful advance
in our knowledge of matter and the mysteries of the atom.
Many other rare elements or their compounds are now being
found to be useful to man in the arts, in medicine, or by the
light they throw on chemical, electrical, or ethereal forces.^
If now we take the occurrence of all these apparently use-
less substances in the earth's crust ; the existence in tolerable
abundance, or very widely spread, of the seven metals known
to man during his early advances towards civilisation, and the
many ways in which they helped to further that civilisation ;
and, lastly, the existence of a few elements which, when spe-
cially combined, produce a substance without which modern
science in almost all its branches would have been impossible,
w^e are broui2:ht face to face with a body of facts which are
wholly unintelligible on any other theory than that the earth
(and the universe of which it form> a part) was constituted
1 While this chapter is being written I see it announced that two of the
rarest of the elements, lanthanium and noodyniuin. have l)ei'n found to pro-
vide (through some of their comjiounds) light-lilters, which increase the
efficiency of the spectroscope in <1h» study of the planetary atmospheres,
and may thus be the menus of still furthoi- extending oiu* knowledge of the
universe.
390 THE WOKLD OF LIFE
as it is in order to supply us, when the proper time came, with *
the means of exploring and studying the inner mechanism
of the world in which we live — of enabling us to appreciate
its overwhelming complexity, and thus to form a more ade-
quate conception of its author, and of its ultimate cause and
purpose.
I have already shown that the postulate of a past eternal
existence is no explanation, and leads to insuperable difficulties.
A beginning in time for all finite things is thus demonstrable ^
but a beginning implies an antecedent cause, and it is impos-
sible to conceive of that cause as other than an all-pervading
mind.
The Mystery of Carbon: the Basis of Organised Matter and
of Life
It is universally admitted that carbon is the one element
which is essential to all terrestrial life. It will be interesting,
therefore, to give a brief statement of what is known about
this very important substance. Although it is so familiar to
us in its solid form as charcoal, or in a more mineralised form
as black-lead or graphite, it is doubtful whether it exists un-
combined on the earth except as a product of vegetation.
Though graphite (plumbago) is found in some of the earliest
rocks, yet it is believed that some forms of vegetation existed
much earlier. Graphite has also occurred (rarely) in mete-
orites, but I am informed by my friend. Professor Meldola,
that it cannot be decided whether this is derived from carbon-
dioxide gas or from gaseous carbon. Sir William Huggins
was also doubtful as to the state in Avhich it exists in the sun
and comets, w^hether as carbon-vapour or a hydrocarbon. But
the most interesting point for us is that it exists as a constitu-
ent of our atmosphere, of which carbon-dioxide fonns about
^■g^ooth part, equal to about yoVo't^^ ^2iYi by weight of solid
carbon ; and it is from this that the whole of the vegetable
kingdom is built up. The leaves of plants contain a green
substance named chlorophyll, which by the aid of sunlight can
THE ELEMENTS AND JJFE 391
extract the carbon from the gas, and there is no other means
known hj which this can be done at ordinary temperatures.
The chemist has to use the electric spark, or very high tem-
peratures, to perform what is done by the green leaves at the
ordinary temperatures in which we live.
The reverse operation of combining carbon with other ele-
ments is equally difficult. In Chambers's Encyclopaedia we
find the following statement: '^ At ordinary temperatures all
the varieties of carbon are extremely unalterable ; so much so
that it is customary to burn the ends of piles of wood whirh
are to be driven into the ground, so that the coating of non-
decaying carbon may preserve the inner wood. Wood-charcoal,
however, burns very easily, animal charcoal less so ; then fol-
low in order of difficulty of combustion coke, anthracite, black-
lead, and the diamond." The two latter withstand all tem-
peratures, except the very highest obtainable. These various
states of carbon differ in other respects. Ordinary carbon is
a good conductor of electricity; the diamond is a non-con-
ductor.
Carbon unites chemically with almost all the other elements,
either directly or by the interv^ention of some of the gases. It
also possesses, as Sir Henry Roscoe says : " A fundaiTiental and
distinctive quality. This consists in the power which this ele-
ment possesses, in a much higher degree than any of the others,
of uniting with itself to form complicated compounds, contain-
ing an aggregation of carbon-atoms united with either oxygen,
hydrogen, nitrogen, or several of these, bound together to form
a distinct chemical Avhole.''
Carbon is also the one element that is never absent from
any part or product of the vegetable or animal kingdoms ; and
its more special property is that, when combined with hydro-
gen, nitrogen, and oxygen, together with a small quantity
(about 1 per cent) of sulphur, it forms the whole group <if
substances called albuminoids (of which white of egg is the
type), and which, much diluted, forms the essential part of
the blood, from which all the solids and fluids of organisms
392 THE WORLD OF LIFE
are secreted. It was on these special features of carbon that
Haeckel founded his celebrated carbon-theory of life, which
he has thus stated : '^ The peculiar chemico-physical properties
of carbon — especially the fluidity and the facility of decom-
position of the most elaborate albuminoid compounds of car-
bon — are the sole and the mechanical causes of the specific
phenomena of movement, which distinguish organic from in-
organic substances, and which are called life, in the usual sense
of the word.'' And he adds : " Although this ' carbon-theory '
is warmly disputed in some quarters, no better monistic theory
has yet appeared to replace it."
What a wonderfully easy way of explaining a mystery!
Carbon forms a constituent of the bodies and of the products
of all living things ; therefore carbon is the cause of life and all
its phenomena !
But besides the carbon in the atmosphere an immense quan-
tity exists in the various limestone rocks, consisting of car-
bonate of lime (CaCOg). It is quite possible, however, that
these are all results of animal secretions as in coral-reefs; or
of the debris of the hard parts of marine animals, as in the
Globigerina-ooze. Limestones exist among the oldest rocks,
but as we know that marine life was very much older, this is
no objection. All water holds in solution a large quantity of
carbonic acid gas, so that both air and water are the source
of the most essential elements for building up the bodies of
plants and animals.
The ocean also holds a large amount of carbonate of lime
in solution, and this is kept permanently dissolved by the large
amount of carbonic acid gas always present, which is sufficient
to dissolve five times the amount of carbonate of lime which
actually exists. Deposits of inorganic limestone are, there-
fore, now never formed except by long-continued evaporation
in isolated bodies of salt water. This renders it more probable
that all pure limestone rocks are really very ancient coral-reefs
consolidated and crystallised by heat and pressure under masses
of superincumbent strata.
THE ELEMENTS AMJ EIFE ;]U0
The altogether remarkable and exceptional properties of
carbon are fully reeognised by modern chemists, as well shown
by Professor II. E. Armstrong's statements in his Presidential
Address to the British Association in lUU'J :
"The central luminary of our system, let me insist, is the ele-
ment carbon. The constancy of this element, the firmness of its
affections and affinities, distinguishes it from all others. It is only
when its attributes are understood that it is possible to frame any
proper picture of the possibilities which lie before us of the place of
our science in the cosmos."
And a little further on he says:
" Our present conception is, that the carbon atom has tetrahodral
properties in the sense that it has four affinities which operate
practically in the direction of four radii proceeding from the centre
towards the four solid angles of a regular tetrahedron. . . .
The completeness with which the fundamental properties of the
carbon atom are symbolised by a regular tetrahedron being alto-
gether astounding."
And again :
" It would seem that carbon has properties which are altogether
special; the influence which it exerts upon other elements in de-
priving them of their activity is so remarkable."
We see, therefore, that carbon is perhaps the most unique,
in its physical and chemical properties, of the whole series of
the elements, and so far as the evidence points, it seems to
exist for the one purpose of rendering the development of
organised life a possibility. It further appears that its unique
chemical properties, in combination with those of the other
elements which constitute protoplasm, have enabled the various
forms of life to produce that almost infinite variety of sub-
stances adapted for man's use and enjoyment, and especially
to serve the purposes of his ever-advancing research into the
secrets of the universe.
3yi THE WOELD OF LIFE
Water: its relations to Life and to Man
The compound water is as essential for building up living
organisms as is carbon, and it exhibits peculiarities almost
as striking as those of that element. Its more obvious quali-
ties are singularly unlike those of its components, oxjgen and
hydrogen : oxygen supports combustion, water checks or destroys
it; hydrogen burns readily, water is incombustible. Water is
wonderfully stable at ordinary temperatures, hence it is the
most innocuous of fluids ; it is also an almost universal solvent,
hence its great value in cookery, in the arts, and for cleansing
purposes. Besides being absolutely essential for vegetable and
animal life it has qualities which render it serviceable to civil-
ised man, both in his pleasures and his scientific discoveries.
Absolutely pure water is a non-conductor of electricity; but as
all natural waters contain gases or salts in solution, it then be-
comes a conductor, and is partly decomposed, or becomes an
electrolyte. The various curious facts connected with water
are so puzzling, that in April 1910 the Faraday Society held
a general discussion in order to arrive at some solution of what
is termed in the Electrical Review " the most complex of prob-
lems." One of the facts that seem to be now generally
accepted is, that water is not the simple compound, H2O, it
is usually held to be, but is really a compound of three hydrols,
II2O being gaseous water, (H20)3 being ice, while liquid water
is a mixture of these or (H20)2.
Professor H. E. Armstrong put forward this view in 1908,
and in the Address already quoted he says:
" Although it is generally admitted that water is not a uniform
substance but a mixture of units of different degrees of molecular
complexity, the degree of complexity and the variety of forms is'
probably under-estimated, and little or no attention has been paid
to the extent to which alterations produced by dissolving substances
in it may be the outcome and expression of changes in the water
itself."
THE ELEMENTS AXD LIFE 31)5
And again :
As water is altogether peculiar in its activity as a solvent, and
is a solvent which gives rise to conducting solutions, an explanation
of its efficiency must be souglit in its own special and peculiar
properties."
Here again we find that the most common and familiar of
the objects around us, and wdiich we are accustomed t<t l<M.k
upon as the most simple, may yet really be full of marvel and
mystery.
The strange chemical properties of water are probably the
cause of the singular but most important fact that water reaches
its greatest density at 4°C. (= about 7° F.) above the freez-
ing-point. If this curious anomaly did not exist the coldest
w^ater would ahvays be at the bottom, and would freeze there;
and thus many lakes and rivers during a hard winter would
become solid ice, w-hich the succeeding summer might not bo
able to melt. Sir Henry Koscoe says:
" If it were not for this apparently unimportant property our
climate would be perfectly Arctic, and Europe would in all proba-
bility be as uninhabitable as Melville Island." ^
The very remarkable and highly complex relations between
the quantity of water in our oceans, seas, and lakes, and the
earth's habitability^ have been fully discussed in chapters xii.
and xiii. of my volume on Man's Place in the Tni verse. 1
will only mention here, that in those chapters I liave pointed
out the probable origin of the great oceanic basins; the pro<ifs
of their permanence throughout all geological tinu^; the prob-
able causes of that pennanence; the necessity of such perma-
nence to preserve the continuity of life-dcvel<ipment. not only
on the earth as a whole, but on each of the izvont continents;
and, lastly, how^ all these phenomena have cond)ined to secure
that general uniformity of climatic conditions throughout the
whole period of the existence of terrestrial life which was essen-
1 Elementary Chemistry, p. 38.
396 THE WORLD OF LIFE
tial to its full and continuous development. There is, I be-
lieve, no more curious and important series of phenomena con-
nected with the possibilities of life upon the earth than those
described in the chapters above referred to.
Water as Preparing the Earth for Man
There remain vet some further relations of water to life
which may be here briefly noticed. Among the various agen-
cies that have modelled and remodelled the earth's surface,
water has played the most important part. It is to water that
we owe its infinite variety, its grandeur, its picturesqueness, its
adaptability to a highly varied vegetable and animal life; and
this v/ork has been carried out through its manifold physical
and chemical properties. It is in its three states, solid, liquid,
and gaseous, that water exerts its most continuous and effective
powers; and it is enabled to do this because, though each of
these has its own limited range of temperature, they yet over-
lap, as it w^ere, and can therefore act in unison. Thus within
the narrow limits of temperature adapted to organic life we
have both ice and water-vapour as well as liquid water, in
almost continuous action. Through dew, mist, and rain, water
penetrates every fissure of the rocks ; through the carbonic acid
gas dissolved in it, the rocks are slowly decomposed ; by the
expansion of water between 39° and 32° F. it freezes in the
upper parts of the fissures, and when the temperature continues
to fall the further expansion during ice-crystallisation forces
the rocks asunder. The most massive rocks at high altitudes
are first cracked and fissured by expansion and contraction due
to alternations of temperature caused by sun-heat, then decom-
posed by rain, then fractured by the irresistible force of ice-
formation. On a large scale in polar regions, and everywhere
at great altitudes, snowfields and permanent glaciers are
formed, which not only carry down enormous quantities of
debris on their surfaces or embedded in their substance, but
with the help of that which is carried along the valley-floors
they rest on, and by the enormous weight of the ice itself often
THE ELEMENTS ASD LIFE :]07
miles in thickness, grind out deep valleys and lake-l)n,sins be-
fore cosmic or other agencies cause them to melt away.
This continuous water-action goes on perpetually in every
continent, and is the great agent in producing that inlinite
variety of contour of the land surface — level plains, gentle
slopes, beautifully rounded downs, wave-like undulations, val-
leys in every possible variety, basin-shaped, trough-shaped,
bounded by smooth slopes or rugged precipices, straight or
winding, and often leading us up into the very heart of grand
mountain scenery, with their domes and ridges and rocky peaks,
their swift-flowing streams, rushing torrents, dark ravines, and
glorious cascades, in endless variety, beauty, and grandeur.
And all this we owe to what are termed the "' properties
of water," that extremely simple and unappreciated element,
which still abounds in mysteries that puzzle the men of science.
Without water in all its various forms and with its many useful
but very familiar properties, not only would life on the earth
be impossible, but unless it had existed in the vast profusion
of our ocean depths, and been endowed with its less familiar
powers and forces, the whole world, instead of being a con-
stantly varvinff scene of beauty — a verv" e:arden of delights
for the delectation of all the higher faculties of man, — would
have been for the most part a scene of horror, perhaps the
sport of volcanic agencies of disruption and upheaval only
modified by the disintegrating effects of sun and wind-action.
Our earth mi2:ht thus have been in a state not verv dissimilar
from that in which the moon appears to be ; not perhajis with-
out a considerable amount of life, but with little of its variety,
and with hardly any of that exquisite charm of contour and veg-
etation which we are now only beginning to appreciate and
to enjoy.
CHAPTEK XIX
IS NATURE CRUEL ? THE PURPOSE AND LIMITATIONS OF PAIN
A VERY large number of persons of many shades of opinion
and various degrees of knowledge are disturbed by the con-
templation of the vast destruction of life ever going on in the
world. This disturbance has become greater, has become a
mystery, almost a nightmare of horror, since organic evolution
through the survival of the fittest has been accepted as a law
of nature. The working out of the details of the Darwinian
theory has forced public attention to this destruction, to its
universality, to its vast amount, to its being the essential means
of progress, to its very necessity as affording the materials for
that constant adaptation to changes in the environment which
has been essential for the development of the whole organic
world.
The knowledge of this startling fact has come to us at a
time W'hen there is a great deal of humanity in the world, when
to vast numbers of persons every kind of cruelty is abhorrent,
bloodshed of every kind is repugnant, and deliberate killing
of a fellow-man the greatest of all crimes. The idea, there-
fore, that the whole system of nature from the remotest eons
of the past — from the very first appearance of life upon the
earth — has been founded upon destruction of life, on the daily
and hourly slaughter of myriads of innocent and often beau-
tiful living things, in order to support the lives of other crea-
tures, which others are specially adapted to destroy them, and
are endowed w^ith all kinds of w^eapons in order that they may
the more certainly capture and devour their victims, — all this
is so utterly abhorrent to us that w-e cannot reconcile it with
an author of the universe who is at once all-wise, all-powerful,
and all-good. The consideration of these facts has been a mys-
398
IS XATURE CKUEL? 399
tery to the religious, and has undoubtedly aided in the produc-
tion of that widesj^read pessimism which exists to-day; whiK-
it has confirmed the materialist, and great numbers of students
of science, in the rejection of any supreme intelligence as hav-
ing created or designed a universe which, iK'ing founded on
cruelty and destruction, they believe to be innnoral.
I am not aware that Darwin dealt with this question at all,
except in the concluding words of his Origin of Species, where
he says:
" Thus, from the war of nature, from famine and death, the
most exalted object we are capable of conceiving, namely, the pro-
duction of the higher animals, directly follows."
This admits the facts as generally conceived; and, without
palliating them, sets on the other side the great compensating
result.
Much more to the point is the concluding sentence of his
chapter on the Struggle for Existence :
" When we reflect on this struggle, we may console ourselves
with the full belief, that the war of nature is not incessant, that no
fear is felt, that death is generally prompt, and that the vigorous,
the health}^, and the happy survive and multiply."
These statements are, I believe, strictly true, but they do not
comprise all that can be said on the question. Before dealing
w^ith the whole subject from the standpoint of evolution, 1 will
quote the opinions of tw^o eminent biologists, as showing how
the matter has impressed even thoughtful and instructed
writers. Professor J. Arthur Thomson (of Aberdeen Tni-
versity), wdien reviewing my Darwinism in The Theological
Eeview, said:
"Tone it down as you will, the fact remains that "Darwinism
regards animals as going upstairs, in a strugirle for individual ends,
often on tlie corpses of their fellows, often Ity a hlood-and-iron com-
petitinn, often by a strange mixture of blood and cunning, in which
eacli looks out for liimsolf and extinction besots the hindmost. We
400 THE WORLD OF LIFE
are not interested in any philosophical justification of this natural
or unnatural method until we are sure that it is a fact."
These words do not, I hope, represent the Professor's view
to-day ; and I believe I shall be able to show that they by no
means give an accurate impression of what the facts really
are. About the same period the late Professor Huxley used
terms still more erroneous and misleading. He spoke of the
myriads of generations of herbivorous animals which '' have
been tormented and devotired by carnivores " ; of the carnivores
and herbivores alike as being " subject to all the miseries inci-
dental to old age, disease, and over-multiplication " ; and of
the " more or less enduring suffering '' which is " the meed of
both vanquished and victor " ; and he concludes that, since thou-
sands of times a minute, were our ears shai'p enough, we should
hear sighs and groans of pain like those heard by Dante at
the gate of Hell, the world cannot be governed by w^hat we
call benevolence.-^ Such a strong opinion, from such an author-
ity, must have influenced thousands of readers ; but I shall be
able to show that these statements are not supported by facts,
and that they are, moreover, not in accordance wdth the prin-
ciples of that Darwinian evolution of which Huxley was so
able and staunch a defender.
It is the influence of such statements as these, repeated and
even exaggerated in newspaper articles and reviews all over
the country, that has led so many persons to fall back upon the
teaching of Haeckel — that the universe had no designer or
creator, but has always existed ; and that the life-pageant, with
all its pain and horror, has been repeated cycle after cycle from
eternity in the past, and will be repeated in similar cycles for
ever. We have here presented to us one of the strangest
phenomena of the human mind — that numbers of intelligent
men are more attracted by a belief which makes the amount
of pain which they think does exist on the earth last for all
eternity in successive worlds without any permanent and good
iThe Nineteenth Century, February 1888, pp. 162-163.
IS NATURE CRUEL? 401
result whatever, than by another belief, wliich admits the suiiio
amount of pain into one earth only, and for a limitod period,
while whatever pain there is only exists for the grand ])iirpose
of developing a race of spiritual beings, who may thereafter
live without physical pain — also for all eternity I Tu put it
shortly — they prefer the conception of a universe in which
pain exists perpetually and uselessly, to one in whieli the pain
is strictly limited, while its beneficial results are eternal!
Xone of these writers, however, nor, so far as T know, anv
evolutionist, has ever gone to the root of the problem, by con-
sidering the very existence of pain as being one of the essential
factors in evolution; as having been developed in the animal
world for a purpose ; as being strictly subordinated to the law
of utility ; and therefore never developed beyond what was
strictly needed for the preservation of life. It is from this
point of view that I shall now discuss the question, and it will
be found that it leads us to some very important conclusions.
In order to do this, we must consider what were the conditions
of the problem when life first appeared upon the earth.
The general facts as to the rate of increase of animals and
plants have been given in Chapter VII. of this work ; but even
these facts, remarkable as they are, seem altogether insignifi-
cant when compared with those of the lowest fonns of life.
The most startling calculation of the kind I have seen was given
last year in a Royal Institution lecture on The Physical Basis
of Life, by W. B. Hardy, F.R.S. (a Cambridge tutor), as to
one of the infusoria (Paramecium) much used for experiment
and observation on account of its comparatively large size
(about T^ijth inch long) and its being veiw easily procured.
This species multiplies by division about twice in three days, and
has been kept under observation thus multiplying for more
than 100 generations. ]N'ow it is not very difiieult to calcnlato
what quantity of Paramecia would be produced in any given
number of generations, and what space they would occupy.
Xo non-mathematical person can imagine or will Wieve the
result. It is, that if the conditions were such (ns regards
40^ THE WORLD OF LIFE
space, food, etc.) that the Paramecivim could go on increasing
for 350 generations, that is to say, for about two years, the
produce would he sufficient in bulk to occupy a sphere larger
than the known universe!
I^ow taking this as a type of the Protozoa — the one-celled
animals and plants that still exist in thousands of varied forms
— we see in imagination the beginnings of the vast world of
life ; and we also see the absolute necessity — if it was to con-
tinue and develop as it has done, filling the earth with infinite
variety, and beauty, and the joy of life — for higher and
higher forms to come successively into being, and for these
forms to exist upon the food provided by the bodies of the
lower. It follows that almost simultaneously with the first
plant-cells which had the power of extracting carbon from the
carbonic acid gas in the air and water and converting it into
protoplasm, the first animal cells must also have arisen; and
both must very rapidly have diverged into varied forms in
order to avoid the whole of the water from being monopolised
by some one form of each, and thus checking, if not altogether
preventing, the development of higher and more varied forms.
Variation and selection were thus necessary from the very first
— ^ were even far more necessary than at any later period, in
order to avoid the possibility of the whole available space being
occupied by some very low form to the exclusion of all others.
Some writers have thought that, owing to the very uniform
conditions in the primeval ocean, the development of new forms
of life would then proceed more slowly than now. But a con-
sideration of the enormously rapid increase of primitive life
leads to the conclusion that the reverse was the case. It seems
more probable that evolution proceeded as much more rapidly
than now, as the rate of increase of the lower animals is more
rapid than that of the highest animals. This view is supported
by the fact, observed long ago in the Foraminifera, that their
variability was immensely greater than in any other animals ;
and this will serve to shorten the time required for the develop-
IS NATURE CRUEL? 403
ment of the life of the Cambrian period from the earliest one-
celled animals.
We find, then, that the whole syj^tcm of lifc-chn'elopmcnt is
that of the lower providing food for th(^ hi^lur in ever-expand-
ing circles of organic existence. That system has succeeded
marvelh)usly, even gloriously, inasmuch as it has produced, as
its final outcome, Max, the one being who can ai)preciate the
infinite variety and beauty of the life-world, the one being who
can utilise in any adequate manner the myriad products of its
mechanics and its chemistry. Now, whatever view we may
take of the universe of matter, of life, and of mind, this suc-
cessful outcome is a proof that it is the only i)racticable metlnjd,
the only method that could succeed. Uor if we assume (with
the monists) that it has been throughout the outcome of the
blind forces of nature — of '^ the rush of atoms and the clash
of w^orlds " — then, as they themselves admit, being the out-
come of a past eternity of trial and error, it could not have
been otherwise. If, on the other hand, it is, as 1 urge, the
foreordained method of a supreme mind, then it must with
equal certainty be the hest, and almost certainly the onJn
method, that could have subsisted through the immeasurable
ages and could have then produced a being capable, in some
degree, of comprehending and appreciating it. For that is
surely the glory and distinction of man — that he is continually
and steadily advancing in the Txnowledge of the vastness and
mvstery of the universe in which he lives: and how anv stu-
dent of any part of that universe can declare, as so numy do,
that there is only a difference of degree between himself and
the rest of the animal-world, — that, in Tlaeckel's forcible
words, '" Our own human nature sinks to the level of a ]dacental
mammal, which has no more value for tlie universe at large
than the ant, the fly of a summer's day, the microscopic infu-
sorium, or the smallest baeillu>^." — i< altoo;other beyond mv
comprehension.^
1 See The Riddle of the Universe, chap. xiii. (p. 87, col. 1).
404 THE WORLD OF LIFE
The Evolution of Pain
Taking it then as certain that the whole world-process is as
it is, because it is the only method that could have succeeded,
or that if there were alternative methods this was the best, let
us ascertain what cojiclusions necessarily follow from it. And,
first, we see that the whole cosmic process is based upon funda-
mental existences, properties, and forces, the visible results of
which we term the '' laws of nature,'' and that, in the organic
world at all events, these laws bring about continuous develop-
ment, on the whole progressive. One of the subsidiary results
of this mode of development is, that no organ, no sensation, no
faculty arises before it is needed, or in a greater degree than
it is needed. This is the essence of Darwinism. Hence we
may be sure that all the earlier forms of life possessed the
minimum of sensation required for the purposes of their short
existence ; that anything approaching to what we term '' pain "
was imknown to them. Thev had certain functions to fulfil
which they carried out almost automatically, though there was
no doubt a difference of sensation just enough to cause them to
act in one way rather than another. And as the whole purpose
of their existence and rapid increase was that they should pro-
vide food for other somewhat higher forms — in fact, to be
eaten — there was no reason whatever whv that kind of death
should have been painful to them. They could not avoid it,
and were not intended to avoid it. It may even have been not
only absolutely painless but slightly pleasurable — a sensation
of warmth, a quiet loss of the little consciousness they had,
and nothing more — " a sleep and a forgetting."
People will not keep always in mind that pain exists in the
world for a purpose, and a most beneficent purpose — that of
aiding in the preservation of a sufficiency of the higher and
more perfectly organised forms, till they have reproduced their
hind. This being the case, it is almost as certain as anything
not personally known can be, that all animals which breed very
rapidly, which exist in vast numbers, and which are necessarily
IS NATURE CRUEL? 405
kept down to their average population by the agency of those
that feed upon them, have little sensitiveness, perhaps only a
slight discomfort under the most severe injuries, and that they
probably suffer nothing at all when being devoured. For why
should they ? They exist to be dt.'voured ; their enormous pow-
ers of increase are for this end; they are subject to no danger-
ous bodily injury until the time comes to be devoured, and
therefore they need no guarding against it through the agency
of pain. In this category, of painless, or almost painless ani-
mals, I think we may place almost all aquatic animals up to
fishes, all the vast hordes of insects, probably all IMollusca and
worms; thus reducing the sphere of pain to a minimum
throughout all the earlier geological ages, and very largely even
now.
When we see the sharp rows of teeth in the earlier binU
and flying reptiles, we immediately think of the pain suffered
by their prey ; but the teeth were in all probability necessary
for seizing the smooth-scaled fishes or smaller land-reptiles,
which were swallowed a moment afterw^ards ; and as no useful
purpose would be served by the devoured suffering pain in the
process, there is no reason to believe that they did so suffer.
The same reasoning will apply to most of the smaller birds
and mammals. These are all so wonderfullv adjusted to their
environments, that, in a state of nature, they can hardly suffer
at all from what we teinn accidents. Birds, mice, squiiTcls,
and the like, do not get limbs broken by falls, as we do. They
leani so quickly and certainly not to go beyond their powers
in climbing, jumping, or flying, that they are probahly never
injured except by rare natural causes, such a^^ lightning, hail,
forest-fires, etc., or by fichtino- amono' themselves; and those
who are injured without being killed by thc-^e various causes
form such a minute fraction of the whole as to be reasonably
negligible. The wounds received in fighting seem to be rarely
serious, and the rapiditv with whidi <uch wonn<ls h(>al in a
state of nature shows that whatever pain exists is not long-
continued.
406 THE WOKLD OF LIFE
It is only the large, heavy, slow-moving mammals which can
be subject to much accidental injury in a state of nature from
such causes as rock-falls, avalanches, volcanic eruptions, or
falling trees ; and in these cases by far the larger portion would
either escape unhurt or would be killed outright, so that the
amount of pain suffered would, in any circumstances, be small ;
and as pain has been developed for the necessary purpose of
safe-guarding the body from often-recurring dangers, not from
those of rare occurrence, it need not be very acute. Perhaps
self-mutilation, or fighting to the death, are the greatest dan-
gers which most wild animals have to be guarded against ; and
no very extreme amount of pain would be needed for this pur-
pose, and therefore w^ould not have been produced.
But it is undoubtedly not these lesser evils that have led to
the outcry against the cruelty of nature, but almost wholly
what is held to be the widespread existence of elaborate con-
trivances for shedding blood or causing j^ain that are seen
throughout nature — the vicious-looking teeth and claws of the
cat-tribe, the hooked beak and prehensile talons of birds of
prey, the poison fangs of serpents, the stings of wasps, and
many others. The idea that all these w^eapons exist for the
purpose of shedding blood or giving pain is wholly illusory.
As a matter of fact, their effect is whollv beneficent even to
the sufferers, inasmuch as they tend to the diminution of pain.
Their actual purpose is always to prevent the escape of cap-
tured food — of a w^ounded animal, which would then, indeed,
suffer useless pain, since it would certainly very soon be cap-
tured again and be devoured. The canine teeth and retractile
claws hold the prey securely ; the serpent's fangs paralyse it ;
and the w^asp's sting benumbs the living food stored up for its
young, or serves as a protection against being devoured itself
by insect-eating birds ; which latter, probably, only feel enough
pain to warn them against such food in future. The evidence
that animals which are devoured by lion or puma, by wolf or
wdld cat, suffer very little, is, I think, conclusive. The sud-
denness and violence of the seizure, the blow of the paw, the
IS XATUKE CiWELi 407
simultaneous deep wounds by teeth and claws, either cause
death at once, or so paralyse the nervous system that no pain
is felt till death very rapidly follows. It must be remembered
that in a state of nature the Carnivora hunt and kill to satisfy
hunger, not for amusement; and all conclusions derived from
the house-fed cat and mouse are fallacious. Even in the case
of man, with his highly sensitive nervous system, which has
been developed on account of his unprotected skin and excessive
liability to accidental injury, seizure by a lion or tiger is hardly
painful or mentally distressing, as testified by those who have
been thus seized and have escaped.^
Our whole tendency to transfer our sensations of pain to all
other animals is grossly misleading. The probability is, that
there is as great a gap between man and the lower animals in
sensitiveness to pain as there is in their intellectual and moral
faculties; and as a concomitant of those higher faculties. We
require to be more sensitive to pain because of our bare skin
with no protective armour or thick pads of hair to ward off
blows, or to guard against scratches and wounds from the many
spiny or prickly plants that abound in every part of the world ;
and especially on account of our long infancy and childhood.
And here I think I see the solution of a problem which has
long puzzled me — wJiy man lost his hairy covering, especially
from his back, where it would be so useful in carrying off
rain. He inaij have lost it, gradually, from the time when he
first became Man — the spiritual being, the 'Miving soul" in
a corporeal body, in order to render him 7nore se7isitivc. From
that moment he was destined to the intellectual advance which
we term civilisation. He was to be exposed to a thousand self-
created dangers totally unknown to the rest of the animal world.
His very earliest advance towards civilisation — the use of fire
— became thenceforth a daily and liourlv danger to him, to be
guarded against only by sudden and acute pain ; and as he
advanced onwards and his life became more complex; as he
surrounded himself with dwellings, and made clothing and
1 See a brief discussion «>f tliis snl»jc<'t in my Darwinism, i>]>. :^()-40.
408 THE WOKLD OF LIFE
adopted cookery as a daily practice, he became more and more
exposed to loss, to injury, and to death from fire, and thus
would be subject to the law of selection by which those less
sensitive to fire, and therefore more careless in the use of it,
became eliminated.
Ilia tools continually becoming more and more dangerous,
and his weapons becoming more and more destructive, w^ere
alike a danger to him. The scythe and the sickle caused acci-
dental woimds, as did the needle and the knife. The club and
the axe, the spear and the arrow, the sword and the dagger,
caused wounds which, if not avoided, led quickly to death.
Hence beneficent pain increased with him as a warning of dan-
ger, impelling him to the avoidance of wounds by skill and
dexterity, by the use of padded clothing or of flexible armour;
w^hile nature's remedies were sought out to heal the less deadly
injuries, and thus avoid long suffering or permanent disable-
ment. And ever as civilisation went on, such dangers in-
creased. Explosives caused a new kind of wound from musket
or pistol, and later from bombs and mines. Boats and ships
were built and the ocean traversed. Endless forms of machin-
ery were invented, at first hand-worked, and not dangerous to
the worker, but soon driven by steam with such force that if
carelessly entangled in it the worker's limbs might be torn from
his body. And all this went on increasing till at last a large
proportion of the human race laboured daily in peril of life
or limb, or of painful wounds, or worse diseases. Against this
vast ever-present network of dangers, together with the ever-
present danger of consuming fire, man is warned and protected
by an ever-increasing sensibility to pain, a horror at the very
sight of wounds and blood ; and it is this specially developed sen-
sibility that we, most illogically, transfer to the animal-world
in our wholly exaggerated and often quite mistaken views as to
the crueltv of nature!
As a proof of the increased sensibility of the civilised as
compared with the more savage races, we have the well-known
IS NATURE CRUEL ^ 409
facts of the natives of many parts of the world enduring what
to us would be dreadful torments without exhibiting any signs
of pain. Examples of this are to be found in almost every
book of travels. I will here only mention one. Among most
of the Australian tribes there is a regular scale of punishment
for various offences. When a man entices awav another man's
wife (or in some other offence of an allied nature) the allotted
punishment is, that the complainant and his nearest relatives,
often eight or ten in number or even more, are to be allowed
to thrust a spear of a certain size into the offender's leg between
ankle and knee. The criminal appears before the chiefs of the
tribe, he holds out his leg, and one after another the members
of the offended family walk up in turn, each sticks in his
spear, draws it out, and retires. When all have done so, the
leg is a mass of torn flesh and skin and blood ; the sufferer has
stood still without shrinking during the whole operation. Tie
then goes to his hut with his wife, lies down, and she covers
the leg with dust — probably fine wood ashes. For a few
days he is fed with a thin gruel only, then gets up, and is very
soon as well as ever, except for a badly scarred leg. Of course
we cannot tell what he actually suffered, but certainly the aver-
age European could not have endured such pain unmoved.
This, however, is only an illustration. It is not essential
to the argument, which is founded wholly on the principles
of Darwinian evolution. One of these principles, much in-
sisted on by Darwin, is, that no organ, faculty, or sensation
can have arisen in animals except through its utility to the
species. The sensation of pain has been thus developed, and
must therefore be proportionate in each species to its needs,
not heyond those needs. In the lowest animals, whose numbers
are enormous, whose powers of increase are excessive, whose
individual lives are measured bv hours or davs, and which
exist to be devoured, pain would bo almost or quite useless, and
would therefore not exist. Only as the organism increased in
complexity, in duratiou of life, nnrl in exposure to danger which
no THE WORLD OF LIFE
migtit possibly lead to its death before it could either leave
offspring or serve as food to some higher form — only then
could pain have any use or meaning.
I have now endeavoured, very roughly, to follow out this
principle to its logical results, which are, that only in the higher
and larger members of the highest vertebrates — mammals and
birds, do the conditions exist which render acute sensations of
pain necessary, or even serviceable. Only in the most highly
organised, such as dogs and horses, cattle, antelopes, and deer,
does there appear to be any need for acute sensations of pain,
and these are almost certainly, for reasons already given, very
much less than ours. The logical conclusion is, therefore, that
they only suffer a very moderate amount of pain from such
bodily injuries as they are subject to in a state of nature.
I have already shown that in most cases, even from our much
higher standard, their death would be rapid and almost pain-
less ; whence it follows, that the widespread idea of the cruelty
of nature is almost wholly imaginary. It rests on the false
assumption that the sensations of the lower animals are neces-
sarily equal to our own, and takes no account whatever of these
fundamental principles of evolution which almost all the critics
profess to accept.
There is, of course, a large body of facts which indicate that
whole classes of animals, though very highly organised, suffer
nothing which can be called pain, as in the insects ; and similar
facts show us that even the highest warm-blooded animals suffer
very much less than we do. But my argument here does not
depend upon any such evidence, but on the universally accepted
doctrine of evolution through adaptation. According to that
theory, it is only life-preserving variations, qualities, or faculties
that have survival value: pain is one of the most important of
these for us, but it is by no means so important to any other
animal, ^o other animal needs the pain-sensations that we
need; it is therefore absolutely certain that no other possesses
such sensations in more than a fractional degree of ours. What
IS NATURE CRUEL? 411
that fraction is we can only roughly estimate by carefully con-
sidering the circumstances of each case. These show that it
is certainly almost infinitesimal in by far the larger part of the
animal kingdom, very small in all invertebrates, moderately
small in fishes and reptiles, as well as in all the smaller birds
and mammals. In the larger of these two classes it is prob-
ably considerable, but still far below that of even the lowest
races of man.
A Possible Misconception
It may be said — I fear it will be said — that this idea of
the lower animals suffering less pain than we suffer will Ix*
taken as an argument in favour of vivisection. Xo doubt it
will; but that docs not in the least affect the actual truth of
the matter, which is, I believe, as I have stated. The moral
argument against vivisection remains, whether the animals suf-
fer as much as we do or only half as much. The bad effect
on the operator and on the students and spectators remains;
the undoubted fact that the practice tends to produce a callous-
ness and a passion for experiment, which leads to unauthorised
experiments in hospitals on unprotected patients, remains; the
horrible callousness of binding the sufferers in the operating
trough, so that they cannot express their pain by sound or
motion, remains; their treatment, after the experiment, by
careless attendants, brutalised by custom, remains ; the argu-
ment of the uselessness of a large proportion of the experi-
ments, repeated again and again on scores and hundreds of
animals, to confirm or refute the work of other vivisectors,
remains ; and, finally, the iniquity of its use to demonstrate
already-established facts to physiological students in hundreds
of colleges and schools all over the world, remains. T myself
am thankful to be able to believe that even the hiijhest animals
below ourselves do not feel so acutely as we do; but that fact
does not in anv wav remove mv fundamental disgust at vivi-
section as being brutalising and immoral.
412 THE WORLD OY LIFE
A Recent Illustration of the Necessity of Pain
Within the last few years we have had remarkable proofs
of the beneficence of pain as a life-saver by the sad results of
its absence. The recently discovered X-rays, so much used
now for localising internal injuries, and of bullets or other
foreign objects in any part of the body, have the property also
of setting up a special internal disorganisation unaccompanied
at the time by pain. The result has been loss of limbs or loss of
life to some of the earlier investigators, and perhaps some in-
jury even to the patients for whose benefit it has been applied.
It seems probable, therefore, that if these rays had been asso-
ciated in any perceptible degTce with the heat and light we re-
ceive from the sun, either the course of evolution would have
been very different from what it has been, or the development of
life have been rendered impossible. Pain has not accompanied
the incidence of these rays on the body, because living organ-
isms have never hitherto been exposed to their injurious effects.
Microbes and Parasites: their Purpose in the Life-World
Much light is thrown on the analogous problem of those
human diseases which are supposed to be caused by germs,
microbes, or 2:)arasites, by the application of the more extended
views of evolution I have advocated in the present volume.
The medical profession aj^pear to hold the view that pathogenic
or disease-producing microbes exist for the purpose of causing
disease in otherwise healthy bodies to which they gain access
— that they are, in fact, wholly evil. It is also claimed that
the only safeguard against them is some kind of ^' anti-toxin "
with which everv one must be inoculated to be saved from the
danger of attack by some or all of the large number of such
diseases which affect almost every organ and function of the
body. This view seems to me to be fundamentally wrong, be-
cause it does not show us any use for such microbes in the
scheme of life, and also because it does not recognise that a
condition nf health is the one and only protection we require
IS NATURE CRUEL? 413
against all kinds of disease; and that to put any product of
disease whatever into the blood of a really healthy person is to
create a danger far greater than the disease itself.
On the general principles of the present argunienr there
can be nothing in nature which is not useful, and, in a broad
sense, essential to the whole scheme of the life-wtudd. (Jn this
principle the purpose and use of all parasitic diseases, including
those caused by pathogenic germs, i?^ to seize upon the less
adapted and less healthy individuals — those which are slowly
dying and no longer of value in the preservation of the species,
and therefore to a certain extent injurious to the race by recpiir-
ing food and occupying space needed by the more fit. Tlicir
life is thus shortened, and a lingering and unenjoyable exist-
ence more speedily terminated. One recent writer seems to hold
this view, as shown by the following passage:
" Before it was perceived that disease is an undisputable battle-
field of the true Darwinian struggle for existence, the tremendous
part which it takes in ridding the earth of weaklings and causing
the survival of health, was all credited to the environment and its
dead physical forces." ^
Bnt in this interesting article the writer elsewhere uses lan-
guage implying that even the healthy require rendering '' im-
mune " against all zymotic diseases. It is tliat idea which I
protest against as a libel on nature and on the Ruler of the
Universe; and in its practice as constituting a crime of equal
gravity Avith vivisection itself.
It will be said that quite healthy persons die (^f thesi^ dis-
eases, but that cannot be proved; and the absolutely universal
fact that it is among those living under unhealthy conditions
in our towns, and cities, and villages, that suft'er most from these
diseases is strongly against the truth of the statement. No
doubt savage races often suffer drearlfully from these diseases;
but savages are no more universally healthy than the more civil-
1 Parasitism and Natural Sclrotioii. l)y R. O. Eccles, M.D., Brooklyn, N.
Y., U. S. A.
414 THE WOELD OE LIFE
ised, though it is usually a different kind of unhealthiness.
The only doctrine on this matter worthy of an evolutionist, or
of a believer in God, is that health of body and of mind are
the only natural safeguards against disease; and that securing
the conditions for such health for every individual is the one
and only test of a true civilisation.
A few words in conclusion on the main question of pain in
the animal world. In my treatment of the subject I believe I
have given imnecessary weight to those appearances by which
alone we judge of pain in the lower animals. I feel sure that
those appearances are often deceptive, and that the only true
guide to the evolutionist is a full and careful consideration of
the amount of necessity there exists in each group for pain-
sensation to have been developed in order to preserve the young
from common dangers to life and limb before they have reached
full maturity. It is exactly the same argument as I have made
use of in discussing the question of how mxuch colour-sense can
have been developed in mammals or in butterflies. In both
cases it depends fundamentally on utilities of life-saving value
as required for the continuance of the race. Hitherto the prob-
lem has never been considered from this point of view, the only
one for the evolutionist to adopt. Hence the ludicrously exag-
gerated view adopted by men of such eminence and usually
of such calm judgment as Huxley — a view almost as far re-
moved from fact or science as the purely imaginary and
humanitarian dogma of the poet:
The poor beetle, that we tread upon,
In corporal sufferance feels a pang as great
As when a giant dies.
Whatever the giant may feel, if the theory of evolution is
true, the '' poor beetle " certainly feels an almost irreducible
minimum of pain, probably none at all.
CHAPTER XX
INFINITE VARIETY THE LAW OF THE UNIVERSE CONCLUSION
Throughout the present work I have liad occasion to call
attention to the endless diversity that characterises both organic
and inorganic nature. In a previous work, Man's Place in the
Universe, I was impressed by the diversity which the new
astronomy had shown to exist throughout the stellar universe.
Since that book was written such remarkable advance has been
made in relation to the nature of matter itself, as to constitute
almost a new science. It seems desirable, therefore, to say a
few words here upon the whole question of the variety and
complexity of every part of the material universe in its rela-
tion to man as an intellectual and moral l:)eing, thus summaris-
ing the whole aim and tendency of the present work.
It will, I think, be most instructive to follow the same order
as I have adopted in the present volume, of showing how each
kind of variety and complexity that presents itself to us can
be traced back as dependent upon a preceding complexity,
usually less obvious and more recently brought to light. Thus,
the most obvious of all the diversities in nature is that of the
various forms (or kinds) of animals and plants ; whereas the
diversities of inorganic nature — stones, rocks, etc., are far less
obvious, and were discovered at a much later period.
The Causes of the Diversity of Life-forms
Modern research shows us that the immense diversitv of life-
forms we now find upon the earth is due to two kinds of causes,
the one immediate, the other remote. The iuimediate cause
is (as I have endeavoured to show here), the slow but continu-
ous changes of the earth's surface ns regards contour, altitude,
climate, and distribution of land and water, which successively
415
416 THE WORLD OF LIFE
open new and unoccupied places in nature, to fill which some
previously existing forms become adapted through variation
and natural selection. I have sufficiently shown how this proc-
ess has worked throughout the geological ages, the world's sur-
face ever becoming more complex through the action of the
lowering and elevating causes on a crust which at each succes-
sive epoch has itself become more complex. This has always
resulted in a more varied and generally higher type of vegeta-
tion, and through this a more varied and higher type of animal
life.
The remote but more fundamental cause, which has been
comparatively little attended to, is the existence of a special
group of elements possessing such exceptional and altogether
extraordinary properties as to render possible the existence of
vegetable and animal life-forms. These elements correspond
roughly to the fuel, the iron, and the water which render a
steam-engine possible; but the powers, the complexities, and
the results are millions of times greater in the former, and we
may presume that the Mind which first caused these elements
to exist, and then built them up into such man^ellous living,
moving, self-supporting, and self-reproducing structures, must
be many millions times greater than those which conceived and
executed the modem steam-engine.
Variety of Inorganic Substances
The recognised elements are now about eighty in number,
and half of these have been discovered during the past century ;
while twenty of them, or one-fourth of the whole, have been
added during the last fifty years. These last are all very rare,
but among those discovered in the preceding fifty years are
such now familiar and important elements as aluminium,
bromine, silicon, iodine, fluorine, and chlorine. So far as the
elements are concerned, our earth has doubled in apparent com-
plexity of structure during the last century. But if we take
account of the advance of chemical science, the knowledge that
has been obtained of the inner nature of the best-known older
THE PURPOSE OF DIVEHSITY 417
elements, the wonderfully c'()ini)lr'x laws of tlioir combinations,
and the immense variety of their known eompounds, our ever-
increasing knowledge of the complexity of matter will he vory
much greater.
During the early part of the nineteenth century, tlie old
idea of atoms as being indivisible, incompressible, and inde-
structible particles, almost universally prevailed. They were
usually supposed to be spherical in form, and 1<> 1m^ the scat
of both attractive and repulsive forces, leading to cohesion and
chemical combination. Those of the different elements were
supposed to differ slightly in size, and energy, which led to
their differences of weight and other properties. The whole
conception, though we now see it to be totally inadequate, was
comparatively simple, and with the help of the mysterious elec-
tric and magnetic forces seemed capable of explaining much.
But, decade after decade, fresh discoveries were made ; chem-
ical theory became more and more complex; electricity, the
more it was known the less intelligible it became ; while a host
of new discoveries in the radiant forces of the ether seemed to
show that this mysterious substance was really the seat of all
the forces of the universe, and that the various basic forms of
matter which we term elements were nothing more than the
special manifestation of those forces. It thus became evident
that all our progress in physical science rendered the world of
matter far more wonderful, and at the same time less intel-
ligible than it had ever seemed to us before.^
1 The progress of modern chemistry well shows this increasing com-
plexity with increasing knowledge. The fact of carbon existing in three
distinct forms — charcoal, graphite, and diamond, each with its own special
physical and chemical characters — has already been referred to. Hut it
is found that many other elements have similar properties, especially sili-
con, phosphorus, arsenic, antimony, sulphur, oxygen, and several others.
This curious property is termed allotropy; and it seems somewhat analo-
gous to that property of many compound substances termed isomerism, of
which two striking examples were given at tlie beginning of the last
chapter. Another modern braneh of chemistry is the stuily of the relation
of crystallised substances to polarised light, which reveals nuiny new and
strange properties of identical compounds, and is termed iStcrcochcmistry.
418 THE WORLD OF LIFE
Eetuming now to the different forms under which matter
exists in that portion of the earth which we can examine, we
find them to be very limited as compared with those of the
organic world. The crust of the earth, and presumably the
interior also, consists mainly of what are called minerals, which
is the term used for all chemical compounds of the elements
which have been produced under natural laws and forces, and
constitute the materials of the whole planet. They comprise,
besides the elements themselves, the various salts, alkalis, earths,
metallic ores, precious stones, and crystals, which have a def-
inite chemical constitution, a permanent form, and definite
characters ; forming what are termed mineral species. These,
when disintegrated by natural forces, intermingled in various
ways, and solidified in various degrees, make up the whole mass
of rocks and surface material of the earth. The total number
of mineral-species now known, almost the whole of which are
to be found in the fine mineralogical gallery of the British
Museum, is almost exactly a thousand. Many of these are
very rare or local, the great bulk of the rocks being made up
of a few score, or at most of a few hundreds of them.
The generally accepted idea being that the whole earth was
once a molten mass, the crust may be supposed to give a fair
sample of the whole ; and the additional fact that, during all
geological time, matter from the interior has been brought to
These various properties of the atoms and molecules of matter have so
complicated their relations, that the attempt to unravel them has led to a
system of equations, of diagrams, and of formulae, which are almost as
difficult for the general reader to follow in detail, as is the working out of
some abstruse mathematical investigation. As an example of this complex-
ity in chemical nomenclature I may refer to a recent paper by Sir William
Crookes, on the rare metal scandium (discovered in 1879). Near the
end of this paper (in the Proc. Roy. Soc, series A, vol. 84, p. 84), the
author says : " By the kindness of Dr. Silberrad, I have had an oppor-
tunity of experimenting with octamethyltetraminodihydroxyparadixunthyl-
bezonetetracarboxilic acid."
He then adds : " Previous experiments would lead one to expect the
scandium salt of this acid to have the composition C44H4oOi4N4Se;. The
only scandium salt I could form with this acid has the composition
CssHjgOoaXsSCj.
THE PURPOSE OF DIVEESITY 419
the surface by volcanoes and liot springs, renders it prol>:d)lo
that very few either of the elements or compounds remain
unknown.
The skill of the chemist, however, has led to the production
of a much greater number of stable chemical compounds than
occur in nature. These are used in medicine or in the various
arts, and their numbers are very great. They are usually
divided into two classes, the inorganic and the (jrganic; the
former being of the same nature as tliose of the great bulk of
the mineral species, while the latter, called also carbon-com-
pounds, resemble the products of living organisms of which
carbon is an essential part.
A recent estimate of the known inorganic compounds,
natural and artificial, bv a French chemist is 8000 ; but ^Ir.
L. Fletcher, of the British [Museum, informs me that this
number must onlv be taken as an '' irreducible minimum.''
As to organic compounds, I am told by Professor II. E. Arm-
strong, that they have recently been estimated at about 100,
000 ; but he states that the j^ossihilities of forming such com-
pounds are infinite, that chemists can make them by thousand
if required, and that they now limit themselves to those which
have some special interest. The approximate figures for the
various kinds of stable chemical compounds now known, will
therefore form an easily remembered series : —
Mineral species 1 ,000
Inorganic compounds (artificial) 10,000
Organic compounds (artificial) 100,000
Possible organic compounds Infinite!
What a wonderful conception this affords us of the possi-
bilities of the elements (or rather of about one-fifth of them)
to produce the almost endless variety of natural products in
the vegetable and animn! kinirdoms. Tliese possibilities must
depend upon the "properties" of the elements; not only their
actual properties as elements, but their latent pntperties
through which they not only combine with each other in a
great variety of ways, but, by each eombi nation create, as it
420 THE WOELD OP LIFE
were, a new substance, possessing properties and powers dif-
ferent from those of any other substances whatever. These
almost infinitely various properties of chemical combinations,
together with a host of other problems with which the organic
chemist has to deal, have led some of them to almost exactly
the same conclusion to which I have been led by a more super-
ficial view of the marvels of '' growth " and cell-division in
living organisms. In the Address already quoted, Sir H. E.
Armstrong says, after referring to some of the complex and
extraordinary chemical transformations produced by living
plants :
" The general impression produced by facts such as these is,
that directive influences are the paramount influences at work in
building up living tissues."
And again more explicitly :
" It would seem that control is exercised and stability secured
in several ways; not only is the form laid down in advance but
certain chosen materials are alone available, and the builders can
only unite particular materials in particular ways."
It is very satisfactory to find that both chemists and
physiologists recognise the absolute need of some controlling
and directive power in elaborating the special products or
building up the complex tissues of plants and animals.
The Cause and Purpose of this Variety
The general conclusion to which the whole argument of
this volume tends, is, that the infinite variety we see in nature
can be traced back step by step to the almost infinite complexity
of the cells by means of which they live and gi'ow; of the
protoplasm which is the substance of the cells; of the elements
of which protoplasm consists ; of the molecules of those
elements ; and finally of the atoms whose combination forms
the separate and totally distinct elementary molecules. And
at each step farther back we are as far ofi^ as ever from com-
THE PUliPOSE or DlVEruSITY 421
prehending how it is possible for such infinite diversity to
be brought about. And now that we are led to believe that
the atom itself is highly complex — that it is a system of re-
volving electrons or coi-puscles, held together by tremon«lous
forces — the mystery becomes deeper still, and we find it (piite
hopeless to realise what is the nature of the controlling power
and mind, Avhich out of such unimaginable entities lias built
up the vast material universe of suns and systems of which
our earth foimis a fractional part, together w^ith that even
more complex world of life of which we ourselves are the out-
come.
The overwhelming complexity and divei'sity of this vast
cosmos in its every part and detail, is the great fundamental
characteristic which our highest science has brought promi-
nently to our notice ; but neither science nor religion has given
us the slightest clue as to why it should be so. Science says :
" It is so. Ours not to reason why ; but only to find out what
is.'' Religion says : " God made it so " ; and sometimes adds,
" it was God's will ; it is impious to seek any other reason."
In the present work I have endeavoured to suggest a reason
which appeals to me as both a sufficient and an intelligible
one: it is that this earth with its infinitude of life and beauty
and mystery, and the universe in the midst of which we are
placed, with its overwhelming immensities of suns and nebuho,
of light and motion, are as they are, firstly, for the develop-
ment of life culminating in man ; secondly, as a vast school-
house for the higher education of the human race in pn^jia ra-
tion for the enduring spiritual life to which it is destined.
I have endeavoured to show that some portion at least of
what seems a superfluity of elements in our earth-structure
has ser\'ed the purpose of aiding the gi'adual progress of man
from barbarism to material civilisation ; while another portion
has furnished him with materials which have alone enabled
him to penetrate into the two unkninvn worlds with which ho
was encompassed — those of the nlniost infinitely great and
of the almost infiuitelv little; but both alike attractive an<l
422 THE WOELD OF LIFE
grand in their revelations; both, offering ever-fresh vistas of
unf athomed mysteries ; both impressing upon him the existence
of immanent forces and controlling mind-power as their only
possible cause.
I suggest, further, that these deeper and deeper mysteries
which confront us everywhere as we advance farther in our
knowledge of this universe, are now serving, and will serve
in the future so long as man exists upon the earth, to give
him more and more adequate conceptions of the power, and
perhaps to some extent of the nature, of the author of that
universe ; will furnish him with the materials for a religion
founded on knowledge, in the place of all existing religions,
based largely on the wholly inadequate conceptions and be-
liefs of by-gone ages.
ft
A Suggestion as to the Origin of Life
As it may be expected that I should state what is my ovm
conception of the power which I claim to be proved to exist,
and to be the fundamental cause of the life-world as well as
of the material universe, I will here make a few suggestions
as to what seems to me to be the least improbable, the least
difficult, of all attempts to deal with what Herbert Spencer
held to be " unknowable," but the non-existence of which he
held to be unthinkable. In the Chapter on Religion, in Dar-
win's Life and Letters, he also seems to have rested in the one
conclusion, that the universe could not have existed without an
intelligent cause, but that any adequate conception of the
nature of that cause was beyond the powers of the human mind
to form. With these views I am in complete sympathy; but
I yet think that we can form some conceptions of the powers
at work in nature which help us to overcome the insuperable
difficulty as to the nature of the infinite and absolute creator,
not only of our world and our universe, but of all that exists
or can exist in infinite space. Here, as everywhere in science,
we must not attempt to deal with the ultimate problem with-
THE PUKP08E OF DIVEKSITY 423
out studying or com2:)relieu(]iiig the steps hy which it may be
approached.
I venture to hope that in the present volume, and especially
in the last six chapters, I have satisfied most of my rc^aders
that the vast life-world, with its myriad forms, each one
originating in a single cell, yet growing, by cell-division, into
such marvels of variety, of use, and of beauty, does absolutely
require some non-mechanical mind and power as its efficient
cause. To such onlv mv further ar":ument will be directed.
My first point is, that the organising mind which actually
carries out the development of the life-world need not bo in-
finite in any of its attributes — need not be what is usually
meant by the terms God or Deity. The main cause of the
antagonism between religion and science seems to me to be
the assumption by both that there are no existences capable
of taking part in the work of creation other than blind forces
on the one hand, and the infinite, eternal, omnipotent God on
the other. The apparently gratuitous creation by theologians
of a hierarchy of angels and archangels, with no defined duties
but that of attendants and messengers of the Deity, perhaps
increases this antagonism, but it seems to me that both ideas
are irrational. If, as I contend, we are forced to the assump-
tion of an infinite God by the fact that our earth has developed
life, and mind, and ourselves, it seems only logical to assume
that the vast, the infinite chasm between ourselves and the
Deity is to some extent occupied by an almost inlinite scries
of grades of beings, each successive* grade having higher and
higher powers in regard to the origination, the development,
and the control of the universe.
If, as I here suggest, the whole* purport of the material
imiverse (our universe) is the development of spiritual beings
who, in the infinite variety of their natures — what we term
their characters, — shall to some extent reflect that infinite
variety of the whole inoriranic and orijanie worlds through
which they have been developed; and if we further suppose
424 THE WORLD OF LIFE
(as we must suppose if we owe our existence to Deity) that
such variety of character could have been produced in no other
way; then we may reasonably suppose that there may have
been a vast system of co-operation of such grades of being,
from a very high grade of power and intelligence down to
those unconscious or almost unconscious ^' cell-souls " posited
by Haeckel, and w^hich, I quite admit, seem to be essential
coadjutors in the process of life-development.
Xow granting all this, and granting, further, that each
grade of being would be, for such a purpose as this, supreme
over all beings of lower grade, who would carry out their
orders or ideas with the most delighted and intelligent obe-
dience; I can imagine the supreme, the Infinite being, fore-
seeing and determining the broad outlines of a universe which
w^ould, in due course and with efficient guidance, produce the
required result. He might, for instance, impress a sufficient
number of his highest angels to create by their will-power the
2:»rimal universe of ether, with all those inherent properties and
forces necessary for what was to follow\ Using this as a
vehicle the next subordinate association of angels would so act
upon the ether as to develop from it, in suitable masses and
at suitable distances, the various elements of matter, which,
under the influence of such laws and forces as gravitation,
heat, and electricity, would thenceforth begin to form those
vast systems of nebulae and suns which constitute our stellar
universe.
Then we may imagine these hosts of angels, to whom a
thousand years are as one day, watching the development of
this vast system of suns and planets until some one or more
of them combined in itself all those conditions of size, of
elementary constitution, of atmosphere, of mass of water and
requisite distance from its source of heat, as to ensure a
stability of constitution and uniformity of temperature for
a given minimum of millions of years or of ages, as would
be required for the full development of a life-world from
THE PURPOSE OF DiVEiiSiTY 425
Amoeba to Man, with a surplus of a few Inmdred millions
for his adequate development.
Thought-transference as an agent in Creation
In my Man's Place in the Universe I have pointed out
the very narrow range of the quantitative and qualitativp con-
ditions which such a world must possess ; and tlie next stop
in the process of what may be wtU termed " creation '' would
be the initiation of life by the same or a subordinate body of
spirit-workers, whose duty would be, when the waters of the
cooling earth had reached a proper temperature and were
sufficiently saturated with gases and carbon-compounds, to
infuse into it suitable life-centres to begin the process of or-
ganisation, which, as Huxley acknowledged, implies life as its
cause. How this was done it is impossible for us to know,
and useless to speculate; but there are certain guides. From
Haeckel's concession of ^' cell-souls " possessing volition, but
a minimum of sensation, we have one conceivable starting-
point. From Weismann's vivid description of cell-growth and
cell-division, w-ith its complex apparatus, its purposive motions
so evidently adapted to bring about a definite result, and its
invariable onward march to that result, we as surely imply
an intelligence and power far beyond anything we know or can
clearly conceive.
We are led, therefore, to postulate a body of what wo may
term organising spirits, who would be charged with the duty
of so influencing the myriads of cell-souls as to carry out their
part of the work with accuracy and certainty. In the power
of ^' thought-transference " or mental impression, now gener-
ally admitted to be a vera causa, possessed by many, perhaps
by all of us, we can understand how the higher intelligences
are able to so act upon the lower and that the work of the
latter soon becomes automatic. The work of the organisers
is then directed to keeping up the supply of life-material to
enable the cell-souls to perform their duties while tlie cells are
rapidly increasing.
426 THE WORLD OF LIFE
At successive stages of development of the life-world, more
and perhaps higher intelligences might be required to direct
the main lines of variation in definite directions in accordance
with the general design to be w^orked out, and to guard against
a break in the particular line which alone could lead ultimately
to the production of the human form. Some such conception
as this — of delegated powers to beings of a very high, and to
others of a very low grade of life and intellect — seems to me
less grossly improbable than that the infinite Deity not only
designed the whole of the cosmos, but that himself alone is
the consciously acting power in every cell of every living thing
that is or ever has been upon the earth.
What I should imagine the highest intelligence engaged in
the w^ork (and this not the Infinite) to have done would be
so to constitute the substance of our universe that it would
afford the materials and the best conditions for the development
of life ; and also, under the simple laws of variation, increase,
and survival, would automatically lead to the maximum of vari-
ety, beauty, and use for man, when the time came for his ap-
pearance ; and that all this should take place with the minimum
of guidance beyond that necessary for the actual working of the
life-machinery of all the organisms that were produced under
these laws. Some such conception seems to me to be in har-
mony with the universal teaching of nature — everyw^here an
almost infinite variety, not as a detailed design (as when it
was supposed that God made every valley and mountain, every
insect and every serpent), but as a foreseen result of the con-
stitution of the universe. The vast whole is therefore a mani-
festation of his powTr — perhaps of his very self — but by
the agency of his ministering angels through many descending
grades of intelligence and power.
Diversify of Human Character
Many people are disturbed by the now w-ell-established fact
that the effects of use, of training, or of education, are not
inherited; and that though innate mental as well as bodily
THE PURPOSE OF DIVEPSITY 427
characters vary mucli througli inlieritanco these can only l)e
developed in special directions hy some form of selection.
There being very little if any effective selection of character
among civilised people, they therefore fear that there can he
no continued advance of the race. Quite recently 1 have dis-
cussed this question from two points of view. I^y a general
glance over the early history of civilis.'d man 1 have shown
that there is little if any evidence of advance in character «h-
in intellect from the earliest times of which we have anv
record.^ I had already, twenty years ago, shown in some d(»-
tail how, under a rational system of society, in which all the
present soul-degrading influences of individualistic wealth and
poverty would be abolished, (especially as leading to unholy
marriages) a progressive advance in character would neces-
sarily arise through elimination of the worst and most degraded
bv an effective and trulv natural selection.- The following
passage towards the end of the former article will briefly indi-
cate the nature of the argument in both these essays:
" The great lesson taught us by this brief exposition of the
phenomena of character in relation to the known laws of organic
evolution is this: that our imperfect human nature, with its almost
infinite possibilities of good and evil, can only make a systematic
advance through the thoroughly sympathetic and ethical training
of every child from infancy upwards, combined with that perfect
freedom of choice in marriage which will only be possihle wlien all
are economically equal, and no question of social rank or material
advantage can have the slightest influence in determining that
choice."
It now only remains to show, verv brieflv, how tlu^ views
here sketched out are in perfect harmony with the entire scheme
of the life-world. That scheme is shown to be the production
of an almost infinite diversity in forms of life, beautifuUv eo
ordinated for the common good, and for the ultimate develop-
1 " Evolution and Character," Fortnijjhtly Review. January 1. I'JOS.
•-'"Human Selection." Fortni«ilit ly Review. Septj-niber ISOl). Reprinted
in Studies, Scientific and Social, 1900, vol. i. p. 509.
428 THE WORLD OF LIFE
ment and education of an almost equally varied humanity.
That variety has been assured and increased by the rapid de-
velopment of man — from the epoch when he became a liv-
ing soul conscious of good and evil — so far above the beasts
which perish that there was little actual selection except to
ensure health and vigour, and the gradual advance towards
civilisation. All types of character had a fairly equal chance
of survival and of leaving offspring, and thus the continued un-
checked action of the universal law of variation led to an
amount of diversity of human nature far above that of any
of the lower animals. We see this diversity manifested through
all the ages, from the lowest depths of a Nero, a Borgia, or
a De Eetz, to the glorious heights of a Confucius or a Buddha,
a Socrates or a Newton.
But if it had been a law of nature that the effects of educa-
tion should be inherited, then men would have been continually
moulded to certain patterns; originality would have been bred
out by the widespread influences of mediocrity in power, and
that ever-present variety in art, in science, in intellect, in
ethics, and in the higher and purer aspirations of humanity,
would have been certainly diminished. And if it be said that
the very bad would have been made better if educational in-
fluences had been inherited, even this may be doubted; for
in times which permitted so much that was bad, education
often tended to increase rather than diminish the evil. On
the other hand, w^e are more and more coming to see that none
were all bad, and that their worst excesses were due in large
part to the influence of their environment and the fierce temp-
tations to which they were, and still are, so unnecessarily ex-
posed.
But it is when we look upon man as being here for the
very purpose of developing diversity and individuality, to be
further advanced in a future life, that we see more clearly the
whole object of our earth-life as a preparation for it. In this
world we have the maximum of diversity produced, with a
potential capacity for individual educability, and inasmuch as
THE PURPOSE OF DIVEPSTTY 420
every spirit has been derived from tlio Deitv, onlv liuiited
by the time at the disposal of each of us. In tlie sj)ir it-
world death will not cut short the period of educational ad-
vancement. The best conditions and opportunities will be af-
forded for continuous progress to a higher status, while all
the diversities produced here will lead to an infinite variety,
charm, and use, that could probably have been brought about
in no other way.
This is also the teaching of modern spiritualism, and by
this teaching its existence is justified and its truth upheld.
Such teaching pervades all its best literature, of which Poe's
Farewell to Earth, given through the trance speaker Miss
Lizzie Doten, in 1863, is one of the most remarkable.^ He
tells us of the educational value of much that we term pain
and evil in the following lines :
" Gifted with a sense of seeing.
Far beyond my earthly being,
I can feel I have not suffered, loved, and hoped, and feared in vain;
Every earthly sin and sorrow I can only count as gain,
I can chant a grand ' Te Deum ' o'er the record of my pain."
Again, he shows us that struggle and effort are essential
for progress there as here :
*^ Human passion, mad ambition, bound me to this lower Earth,
Even in my changed condition, even in my higher birth.
But by earnest, firm endeavour, I have gained a height sublime;
And I ne'er again — no, never! shall be bound to space or time;
I have conquered! and for ever! Let the bells in triumph chime!
* Come up higher ' ! cry the Angels. * Come up to the Koyal Arch !
Come and join the Past Grand Masters, in the Soul's progressive
march,
0 thou neophyte of "Wisdom ! Come up to tlie Poyal Arch ! '*
1 Of the more serious books tlealing witli tlie ethics and j)liilosophy of
spiritualism, I will only direct the reader's attention to two: Spirit
Teachings, by W. Stainton Moses, M.A.; aii.l Psychic Thilosophy, as the
Foundation of a Religion of Natiiral Law. hy \'. (,". Desertes. To such
of my readers who wisli to obtain some knowledge of the higher aspects of
modern spiritualism, I strongly reconunen«l these two works.
430 THE WORLD OF LIFE
In the preceding verse, however, he has given us the key-
note to the future life, which he speaks of as —
The land of Light and Beauty, where no bud of promise dies;
and then continues —
iC
There, through all the vast Empyrean,
Wafted, as on gales Hesperian,
Comes the stirring cry of ' Progress! ' telling of the yet to be.
Tuneful as a seraph's lyre,
' Come up higher ! Come up higher ! '
Cry the hosts of holy angels : ' learn the heavenly Masonry :
Life is one eternal progress : enter then the Third Degree ; —
Ye who' long for light and wisdom seek the Inner Mystery/ "
Conclusion
In accordance with the views expounded in a former work,
Man's Place in the Universe, I have fully discussed the evi-
dences in plant and animal life indicating a prevision and defi-
nite preparation of the earth for Man — an old doctrine,
supposed to be exploded, but which,, to all who accept the view
that the universe is not a chance product, will, I hope, no
longer seem to be outside the realm of scientific inquiry.
Still more important is the argument, set forth in some
detail, showing the absolute necessity of a creative and directive
power and mind as exemplified in the wonderful phenomena
of growth, of organisation, and fundamentally of cell-structure
and of life itself. This view is strengthened by a considera-
tion of the nature of the elements which alone render life-
development possible.
Herbert Spencer enforced the idea of " variously conditioned
modes of the universal immanent force " as the cause of all
material and mental phenomena, and as the " Unknown Reality
which underlies both Spirit and flatter." I have here ex-
pressed the same views in a more concrete and intelligible
THE PURPOSE OF DIVERSITY 431
manner. This ^' Unknown Reality " is necessarily iiiiiiiitc and
eternal as well as all-knowing, but not necessarily what we
may ignorantly mean by '' omnipotent " or " benevoleiii " in
our misinterjDretation of what we see around us. 1 have, I
hope, cleared aw^ay one of these misinter])r('tati<jns and mis-
judgments in my chapter Is Mature (Jruel (
But to claim the Infinite and Eternal Being as the one
and only direct agent in every detail of the uuiverse seems,
to me, absurd. If there is such an Infinite Being, and if (as
our own existence should teach us) his will and purpose is
the increase of conscious beings, then we can hardly be the
first result of this purpose. We conclude, therefore, that there
are now in the universe infinite grades of power, infinite grades
of knowledge and wisdom, infinite grades of influence of liigher
beings upon lower. Holding this opinion, I have suggested
that this vast and wonderful universe, with its almost infinite
variety of forms, motions, and reactions of part upon part,
from suns and systems up to plant-life, animal life, and the
human living soul, has ever required and still requires the con-
tinuous co-ordinated agency of myriads of such intelligences.
This speculative suggestion, I venture to hope, will appeal
to some of my readers as the best aj^proximation we are now
able to formulate as to the deeper, the more fundamental
causes of matter and force, of life and consciousness, and
of Man himself; at his best, already '^ a little lower than the
angels," and, like them, destined to a permanent progressive
existence in a World of Spirit.
D. H. HILL LIBRARY
North Carolina Stat* College
INDEX
Acidaspis dufresnoyi, 288
Adaptation, some aspects of, 141
Adaptations to drou<j;ht, 72; binls
and insects, 143 ; not eflected by
use, 280; of plants, animals, ami
man, 329
A^Jlusmtrufi felinus, early reptile, 215
Agassiz, a., on deposition by
Mississippi, 192
Allegory, a physiological, 319
Allotropy of elements, 417
Alpine floras not exceptionally rich,
38, 40, 8G
Amblypoda, a sub-order of Ungu-
lata, 235
America, flora of tropical, 59
American bison, former enormous
population of, 124
Ammonites, eccentric forms of, 288
Amceba, description of, 361
Amphibia, earliest forms of, 210
Ancyloceras matheronianum, 290
Andrews, Dr. C. W., discovers an-
cestral forms of elephants in
Egj'pt, 245
AnimalSj numerical distribution of,
89; much less sensitive than man,
405
Anoplotherid.^, ancestral rumi-
nants, 245
Anoplotheriuin commune, skeleton
of, 244
recognition-marks of,
Antelopes,
172
ArchcBopteryx macriira, 230; sie-
mensi, skull of, 231
Arctic lands a birds' paradise, 151
Argyll, Duke of, on humming-
birds, 177
Armstrong, Professor H. E., on
importance of carbon, 393: on
directive influences in growth,
420
Arrhenius, Professor, uu an eter-
nal universe, 379
Arsinoitherium zitteli, skull of. 240
ASTROPOTiiERiA, extinct uniiulatcs,
251
433
Atlantomxirua immanis, a huge dino-
saur, 220
Atoms, early ideas of, 417
Al'STRALIA, extinct tnainniMls (if,
25C
Babirusa, tusks of, 29G
Ballota nigra, local distiiljiitioii of,
15
Balsams, dyes, oils, etc., variety of,
352
Bate-Hardy, ;Mr. W., on arrange-
ment of identical atoms in carbon
compounds, 384
Beccari, Dr., on forest flora of
Borneo, 56
Beetle mimicking wasp, 169
Beetles, number known, 91 ; pecul-
iar British, 135
Being, grades of between us and
Deity, 423
Bird, earliest known, 309
Bird and insect co-adaptation, 142;
teachings of, 164
Bird's wing, the ideal aimed at in,
308; a feather, detailed structure
of, 309; its anniuil regrowth, 311
Bird-colour, extreme diversity not
of survival value to them, 344
Bird-migRj\tion, origin of. 159
Birds, of New CJuinea and Borneo,
53; species of, 93; of six geo-
graphical regions, 96; peculiar to
Britain, 13.'), 13t): arrival of. iti
Arctic regions. 151, 153: number
of species in Arctic region-^. l.")7:
recognition-marks of. 175: the
earliest, 229; recently extinct.
200: loss of teeth in m'odern. 2;il
Birds and insects, proofs of or-
ganising mind, 309
l?iKi)S OF Parauisk, new types of,
2!)7
Bison, former great population of
in America, 124
BoLis. Mr. II.. on flora of ( ape
])eniii>^iila. 40: on orcliids of ('aj)e
peninsula. 41
434
INDEX
Borneo, rich forest flora of, 49;
birds of, 51
Botanical, reserves, advantages of
small, 82
BovERi's experiments on echini, 373
Brain-cavity of Dinocerata very
small, 239
Brains of early vertebrates, small,
291
Brazil,, richness of flora of, 75
Britain, peculiar animals and
plants of, 135
British India, flora of, 47; chief
natural orders of, 48
British plants, numerical distribu-
tion of, 24, 27; of limited range,
26
Brittan, Mr. L. K, on flora of
Jamaica, 67
Brontosaurus excelsus, skeleton of,
221
Butler, Sir W., on mosquito-
swarms, 146
Butterflies, recognition by, 181,
185
Butterexy, stages of development
of, 325; scales on wings of, 325
Butterfly and caterpillar, diverse
structure of, 321
Caltha palustris, wide range of, 19
Cambrian age, first known life of,
207
Campanula isofpTiylla, small range,
20
Cape Colony, flora of, 75
Cape peninsula, rich flora of, 40
Cape Region, rich flora of, 35, 77
Carbon, the mystery of, 390; prop-
erties of, 391; in the ocean, 392
Carnlvora, early forms of, 240; ex-
tinct South AmericaUj 249
Cavies, numerous extinct, 252
Celebes, flora of, 55, 85
Cell, the mystery of, 361; charac-
teristics of, 363; implies an or-
ganising mind, 364; described by
Professor Lloyd-Morgan, 364 ;
Weismann's description of a di-
viding, 365; Weismann's state-
ment of its powers, 369
Cell-problem, concluding remarks
on, 376
Ceratites nodosus, 289
Ceratosaurus nasicornis, skull of,
222
Cetiosaurus leedsi from Oxford clav,
220
Challenger voyage defines area of
deposition, 192
Chemical problems of water, 393;
nomenclature, illustration of com-
plexity of, 418 *u
China and Coreaj flora of, 34
Christianity, gradual rise of a
purer, 302
Cities, the "wens" of civilisation,
308
CoaLj wide distribution of palaeo-
zoic, 212; prepared atmosphere
for higher life, 213
Cobbett, William, on "wens," 308
Cockerell, on tropical species as
compared with temperate, 104
Coleoptera, number of British, 90;
number known, 91
Colour, for concealment, 169; ex-
tremes of, 298; of flowers sup-
posed to show inedibility, 332;
purpose of in nature, 334; of
plants and animals in relation to
man, 340; our sensations of, an
argument for design, 348, 349
Colour-sense not identical in birds,
mammals, and man, 325, 342
Colours of butterflies, uses of, 183
Colours and ornaments of males,
how caused, 282
Compounds, inorganic, number of,
418; number of organic (artifi-
cial), 419
Condylarthra, 235
Conocoryphe sultzeri, 287
Continental extensions, appendix
on, 268; great difficulties of, 269,
270
Continents, how built up, 196, 198
Coryphodon, an early ungulate, 235
Creators of matter and life not
necessarily omnipotent, 422
Creodonta, early carnivores, 242
Crioceras emerici, 289
Crookes, Sir W., gives an example
of complex chemical nomencla-
ture, 418
Cruelty of nature, supposed, 398
Crustacea, early appearance of,
210
D^dicurus, giant extinct arma-
dillo, 252
Darwin on flora of a very small
area, 87; on increase of elephant,
123; on Porto Santo rabbits, 137;
on the uses of colour to plants,
329; on cross-fertilisation of
flowerSj 330; on war of nature.
INDEX
435
399; on intelligent cause of the
universe, 422
Darwinism, extensions of, 271
Deane, Mr. H., on flora of Sydney,
New South Wales, 42
De Candolle, a., on botanical gco^j;-
raphy, 18, 24; botanical regions
of, 20
Definition of life, 3
Denudation, rate of, measured, 189
Deposition, area of, 191
Determinants, meaning of, 293
Development, reversal of, 245;
cases of extreme, 29G
Diagram of human stature, 116; of
variation of rice-bird, 118; of
nuclear division, 370; of isomer-
ism, 384
Dicynodon lacerticeps, early reptile,
214
Dimetrodon, extinct reptile from
Permian of Texas, 215
Dinocerata, " terrible horned
beasts," 236
DiNOSAURIA, 217
DiPLODOCUS, skull of, 222
Diplodocus carnegii, skeleton of,
220
Diprotodon australis, skull of, 257
DiPTERocARPS, abundance of in
Borneo, 56
Directive agency not explained by
Darwin's *' pan-genesis " nor any
other theory, 319, 358; indica-
tions of, 354; at work, 373, 374
Distribution of species result of
continuous adaptation, 103
Domestic animals, uses of, 305
Dresser, Mr. H. E., on birds breed-
ing in Arctic regions^ 155; on
mosquitoes as food for birds, 157
Drosera rotundifolia, wide range of,
18
Drought, adaptations of plants to,
72
DwiNA river, rich deposits with
early reptiles, 214
Earth's surface changes a cause of
evolution, 187 ; thickness of crust
of, 194; crust floats on melted in-
terior, 195; eff'ect of cooling ami
contracting, 19G; surface-motions,
long persistence of, 200 ; remlered
habitable by water, 3!)6
Eccentricity in nature, 298
Eccles, Dr. R. G., on uses of par;i-
sites, 413
Echinus microtuhcrculutus, egi^ of,
373
Edentata, extinct S. American, 252
Educational elTects. unlimited in
tiie spirit-worlfl. 4'JM
Elements in nlalion to tiie life-
\\orI(l, 3S:{ : important and unim-
portant, 385; list of important,
38(i ; in iclation to man, 387
Elephants, rate of increase of, 123;
the origin of, 244 ; diagram of
development of, 24(1
Elephas gatusa, enormous tusks of,
287; prim'ujcniuHy .skeleton of,
249
Eternity as explaining evolution
fallacious, 37!>
European floras in dilTerent lati-
tudes, 32; compared, 36
Evolution, motive power of or-
ganic, 187
Extensions of Darwinism, 271
Extinction of pleistocene mam-
mals, cause of, 261
Feathers, marvel and mystery of,
309
Female choice, new argument
against, 184
Ferns, extreme abundance of, in the
Philippines, 54
Fishes, peculiar British, 135; the
earliest known, 208; types of
tails of, 209
Fletcher, Mr. L., on inorganic
compounds, 419
Flight of birds and insects com-
pared, 94
" Flora Orientalis," species in. 34
Flora of China, 34; of Chile, 35;
of Cape region, 35; of tropical
Asia, 46; of British India, 47; of
;Malay Peninsula, 47; of Borneo,
49; of Indo-Ciiina, 50; of Malay
Islands, 50; of New C.uinea, 55;
of Philij)pine8, 54; of CeleU's, 55,
85; of (.4)ueensland, 58; of trop-
ical Africa, 59; of Madagascar,
59; of tropical America. 58, 59,
()5 ; of lirazil, 63; of Mexico luid
Central America, 64; of Jamaica,
67; of Trinidaii, 67; of CJulapa-
gos Islamls. 67; of I^igoa Santa.
67, 77; of Penang, 79; of Kain-
bangan Islamls, 80; of Pange-
ranifo. 81 ; of mountains in .la-
pan. SCf. of very small areas. 87
I'l.ouAS of (liirercnt regions com-
parctl. 11; of counties compared.
436
IKDEX
27 ; of some parishes, 28 ; of small
areas, 28, 77 ; of temperate zones
30; cause of richness
35; warm temperate
compared, 3G; of European small
and
86;
compared,
of some.
areas, o/ ; of mountains
plains compared, 38, 40,
extra-European temperate, 39
Flowering plants, peculiar British,
134
Flowers, al)undance of, within Arc-
tic circle, 153
Food of young birds, 142
Forbes, Mr. H. 0., on self-fertilisa-
tion of orchids, 332
Forest reserves, advantages of
small botanical, 79
Fruits, colour of, 336
Galapagos, flora of, 67
Galton's law of heredity, 110
Gamble, Mr. J. T., on flora of
Malay Peninsula, 47
Gardner, on flora of Brazil, 77;
on supposed greater richness of
mountain floras, 80
Gatke, Herr, on bird-migration at
Heligoland, 161
Geese moulting in Arctic regions,
148
Gentiana verna, one locality in
Britain, 26
Geological record, account of, 203;
its three well-marked periods,
204; the teaching of. 300
Geology, as influencing evolution,
188
Germinal selection, 281, 292, 296
Glass essential for science, 338
(ilyptodon clavipes, skeleton of, 253
Glyptodontid.e, extinct armadillos,
252
Grant Allen on insects and colour
of flowers, 333
Grey plover's nest in Arctic re-
gions, 156
Griesbach, on Mediterranean flora.
34; on Brazilian flora, 76
Growth, the nature of, 315; by cell-
division, 316; admitted to be in-
explicable, 371; by cell-division,
what it implies.
Dr., on
Gunther,
94
Haeckel
human
ether, 7,
scions.
373
species
of birds.
on consciousness, o ; on
nature, 6; matter and
,8; on soul-atom uncon-
358; his carbon-theoiv of
life, 391
Hamites rotundity, 290
Hardy, Mr. W. B., on complexity of
proteid molecule, 383
Hartert, Dr., on peculiar British
birds, 135
Hayati, Mr., on floras of Japanese
mountains, 39, 40
Heat, rate of increase in deep bor-
ings, 194
Heligoland and migrating birds,
160
Hemsley, W. B., on flora of Central
America, 61
Heredity a universal fact, 109;
Galton's law of. 110
Heteroceras etnerici, 289
Hooker, Sir Joseph, on flora of
British India, 47; on primary
floras, 65; on rich flora of Pe-
nang, 77; on floras of very small
areas, 87
Horns as recognition-marks, 173
Horses, extinct South American,
250
Hudson, W. H., on field mice in
Argentina, 132
Human character, diversity of. 426
Hutton, Capt., on recognition-
marks, 178
Huxley, Professor, on nature and
origin of life. 9; on matter and
spirit, 10; on crueltv of nature,
400
Hycenodon cruentus, skeleton of,
242
Hyopotamns hrachyrhynchns, skele-
ton of, 243
Ichthyopterygia, 223
Ichthyosaurus, paddles of, 224
Ichthyosaurus communis, skeleton
of, 224
Iguanodon hemissartensis,
of, 218; skull of, 219
Increase in plants and
121
Indo-China, estimate of flora of, 50
Inheritance of educational results
would have checked diversity, 427
Inorganic substances, varietv of,
416
Inostransevia, huge carnivorous
reptile, skull of, 2l6
Insect life of secondary period, 228
Insect pests, uses of, 142
Insects, known species of, 91; pe-
culiar to Britain, 135; earliest
known. 211; and their metamor-
phosis, 321
skeleton
animals,
i:tTDEX
437
Insects and birds, co-adaptation of,
143
Irish deer, skeleton of, 287
Isomerism explained, 385
Jack-rabbit, E. S. Thompson on,
172
Jamaica, flora of, 67
Japan, mountain floras of, 40
Java, rich flora of, 80
JoRDAX, Dr. K., on phosphorescent
colours in lepidoptera, 347
JuDD, Professor, on strange forms
of ammonites, 87
Kambangan island, rich flora of, 80
Karoo formation, reptiles of, 213
Kearton on increase of rabbits, 122
Kerner, Dr. A., on power of in-
crease of plants, 121 ; on the in-
sect enemies of flowers, 331 ; on
"vital force/' 356; on arrange-
ment of atoms in the carbon-
compounds, 384
KooRDERS, Dr., on the flora of
Celebes, 55, 85; on rich floras of
small areas in Java, 79
Lagoa Santa, flora of, 67, 75
Land-shells, peculiar British, 135
IjAtitude as influencing floras, 31
Lemming, periodical migrations of,
128-30
Lepidoptera, number of British, 89 ;
number known, 91 ; peculiar
British, 135; wealth of colour in,
345-47
Life, definition of, 3 ; Haeckel on,
4, 7 ; the cause of organisation,
8; reactions of animal and plant,
304 ; the sole cause of life, 306 ; a
suggestion as to origin of, 422
Life-deveix)pment of mesozoic era,
231; conclusion on, 299
Life-forms, causes of diversity of,
415
Life-world, progressive development
of, 203
Limestone, progressive increase of,
234
lAthospermiim gastoni, narrow range
of, 19
Llamas, extinct S. American, 240
Lloyd-Moroan, statement of theory
of germinal selection, 292; on
rapid cell-growth, 375
Ltdekker, jSIr., on Patagonian mar-
supials, 241; on affinities of
American and Australian marsu-
pials, 265
Lyell, Sir C, on causes of extinc-
tion, 264
London, how to stop growth of, 308
LowNE, Mr. B. T., on development
of blow-fly, 323
Machcerodus neogcpua, skull of, 286
Macrmichenia patachonica, 251
Macroscaphiies ivanii, 290
Madagascar, flora of, 59
M cerifherium lyonsi, skull of, 244
Malay Islands, flora of, 50; in-
sects of, 92
Malay Peninsula, table of chief
orders of plants, 47 ; character-
istic plants of, 48
Mammalia, teachings of pleistocene,
265
Mammals, extinct Australian, 256
Man, the cause of extinction of
pleistocene mammals, 268-70; the
glory and distinction of, 402-06;
the most sensitive of organisms,
409
Mantell, Dr., discovered extinct
reptiles in Kent, 217
Marsh, Professor O. C, on Bronto-
saurus, 220; on Dinocerata, 237;
on small brains of early mam-
mals, 239; causes of extinction of
mammals, 263
Marsupials in Patagonian miocene,
240; of the Australian type still
living in the Andes, 264
Martius's flora of Brazil, 63
Mastigophora, 362
Mastodon in S. America, 254
Mastodon americanus, skeleton of,
247
Mastodons, less developed ele-
phants, 246
Max Verworu on chemistry of pro-
toplasm, 316; on vital force, 317
Mediocrity, recession towards, 117
^Mediterranean flora, species in, 34
Megatherium, extinct ground sloth,
252
Megatlierium giganteum, restoration
of, 254
Mendelism and mutation inefficient
as substitutes for Darwinian evo-
lution, 133
]\rKRRiLL, Mr. E. D., on flora of the
Pliilii)pines, 54
Mesozoic era, 213; mammalia of,
228: insects of, 228; life-develop-
ment of, 231
438
INDEX
Metals, the seven ancient, 387; es-
sential for civilisation, 388
Metamorphosis of insects, 321
Mexico and Central America, flora
of, 64
Microbes, use of in nature, 412
Migration, origin of bird, 159;
facts and inferences, 160-63
Mimicry, 169
Minahassa, N. Celebes, flora oF, 55,
85
Mind and purpose in life-develop-
ment, 299 ; and life, different de-
grees of, 307; produces brain, 307
Minerals, number of species of,
418
Mivart, St. George, on recognition-
marks, 179
Morgan, Professor L., on germinal
selection, 292; on rapid cell-
growth, 375
Mosquitoes, uses of, 145; descrip-
tion of Arctic, 146; food for most
young birds, 151
Mosses and hepaticse, peculiar
British, 135
Mountain floras, in Japan, 40; not
richest, 97
MtJLLER on insect-fertilisation of
flowers, 333
Mylodon, contemporary of man,
254
Mylodon rohii^tus, skeleton of, 254
Narwhal's tusk an extreme devel-
opment, 296
Natural selection, illustrative cases
of, 134; of sparrows at Ehode
Island, 138; process of at Porto
Santo, 138
Nature, the sanctity of, 301; our
defacement of, 301; is it cruel?
398
New Guinea, biologically unique,
51 ; flora of, 55 : richness of its
bird fauna, 96, 98
Newton, Professor A., on passenger
pigeon, 128
North American floras in various
latitudes, 34
Nototherium, extinct Australian
wombat, 260
Nuclear division, diagram of, 370
Nucleus, importance of, 373
Nummulites, 363
Nuts, why intended to be eaten,
337
Ocean, carbon in, 392
Orchids, abundance of in Cape
Peninsula and New South Wales,
41 ; in British India, 48
Okeodontid.e, early American rumi-
nants, 242
Organising spirit the cause of life-
production and control, 425
Organs, beginnings of new, 271
Ornithosaltiia, 224
Pain, its purpose and limitations,
398; a product of evolution, 404;
beneficent purpose of, 412; where
useless does not exist, 413; in na-
ture, Huxley's exaggerated view
of, 400, 414
Pal.eomastodons, early elephants,
244-45
Palceotherium magnum, restoration
of, 244
Paleozoic era described, 206
Palms, abundance of in the Malay
Peninsula, 47; in the Philippines,
54
Pangerango, Mount, rich flora of,
81
rarndoxides hohemicus, 287
Pariasaurus hainii, skeleton of, 214
Passenger pigeon now extinct, 125;
enormous population of less than
a century ago, 125
Penang, rich flora of, 79
Phascolotherium, 231
Phenacodiis primcBvus, early ungu-
late, 235
Philippines, rich flora of, 54
Physiological allegory on growth,
319
Plant-cell, Kerner on, 371; iden-
tity with animal cell, 372
Plants of wide distribution, 21;
abundance of compared, 23; of
very small areas, numbers of, 98
Pleistocene mammalia, teachings
of, 259
Plesiosaurus macrocephalus, skeleton
of, 222
PoE, extracts from supposed im-
pressional poem by, 428
Porto Santo rabbits, newly formed
species, 137
Potentilla rupestris, one locality in
Britain, 27
PouLTON, Prof. E. B., on beginnings
of new organs, 272
Primates, fossil species of South
America, 249
i:n^dex
439
Primula imperialis, small range, 19
Proteid molecule, complexity of,
383
Prothylacinus, a Patagonian mar-
supial, 240
Protoplasm, its chemical nature,
315
Pteranodon occidentalis, skeleton of,
226; longiceps, skull of, 227
Pterodactyl, restoration of long-
tailed, 22G
Pterodactylus spectahilis, skeleton
of, 225
Ptychoceras emeridanum, 290
Purpose of our universe to produce
variety of human character, 299,
421
Pyrothebia, 251
Queensland, flora of, 58
Rabbits, increase of in Australia,
123
Radiolaria, 362
Radium, its rarity and uses, 389
Ramsay, Sir A., on life of the Cam-
brian age, 207
Recognition by butterflies, 181
Recognition-marks important for
evolution, 168; explained, 170;
objection to answered, 178; gen-
eral conclusions on, 185
Religion, gradual rise of a true,
302
Reptiles, earliest, 214
Reptilian life of secondary period,
227
Retrogressive development in
birds, 309
Rhizopoda, 362
Rice-bird, diagram of variation of,
118
Ridley, Mr., on flora of Singapore,
79
River-basins, rate of denudation of,
189
Roscoe, Sir H., on properties of
carbon, 388; on water in relation
to life, 391
Saleeby, Dr., on eternity as an ex-
planation, 379
Sap, extreme production of, 299
Sauropterygia, 223
Scales on wings of buttciilics, .'l-i.") -.
apparent purpose of, 327
Scelidosaurus harrisoni, skeleton of.
218
Sceloditherium leptocephalum, skel-
eton of, 255
ScLATER, Dr. P. L., on species of
birds, 94
Seeboiim, H., on food of birds in
Arctic regions, 146
Seton-Tiiompson on recognition-
marks, 172
SiiARPE, Dr. B., on species of birds,
94
Shipley, A. E., table of described
animals, 99
Simethis bicolor, one locality of in
Britain, 27
Singaporp:, flora of, 79; destruction
of forest in, 85
Sisymbrium sophin, power of in-
crease of, 121
Small-brained animals, purpose of,
306
South Africa, Cape Region, flora
of, 79
South America, tertiary mammals
of, 249
Spalacotherium, 229
Sparrows at Rhode Island, work of
natural selection on, 138
Species defined, 12; distribution of,
13; uncertainty of limits of, 25;
rarity of precedes extinction, 26;
number of, in relation to evolu-
tion, 100; variation of. 113; ex-
tremely common, 114; to be seen
everywhere, 115
Spencer, H., on co-ordination of
variations, 275; reply to, 276,
277; his " unkno^^^l reality"
more concretely expressed, 430
Spirit-life described (inspiration-
ally) by Poe, 428
Springbok, curious recognition-
mark on, 174
Spruce, Dr., on rich flora of Ama-
zon, 61
Sterrolophus fJabeJIatus, skull of,
219
Stone-curlews, recognition marks
of, 175
Sydnetx", extreme abundance of or-
chids near, 41
Table of De Candolle's botanical
regions, 20; of chief natural
orders in various floras, 22; of
number of species in large and
small areas. 28; of numln^r of
species in difTerent latitudes, 31:
of floras of European oonntries
according to latitude, 31; of
440
INDEX
floras of XortH American areas,
32; of warm temperature floras,
36; of European floras of small
areas, 37; of extra-European
temperate floras, 39; of large
tropical floras, 45; of chief orders
of flora of British India, 47; of
chief orders of tropical Sikkini.
48; of chief orders of Malay
peninsula, 48; of chief orders of
the Philippines, 54; of chief or-
ders of Celebes, 56; of chief or-
ders of Madagascar, 59; of chief
orders in tropical American
floras. 64 ; of chief orders of Mex-
ico and Central America, 65; of
chief orders of Nicaragua to
Panama, 67; of chief orders of
Lagoa Santa, 71; of number of
species in tropical floras of small
area, 77 ; of number of species in
temperate floras of small area,
77; of distribution of lepidoptera
in Britain, 89; of distribution of
coleoptera, 90; of described
species of orders of insects, 91;
of species of birds in Europe, 95;
of species of birds in zoological re-
gions, 96; of described species of
living animals, 99; of percentage
of mean error of variation. 121 ;
of peculiar sub-species of British
birds, 136; of rate of lowering of
river-basins, 189
Teeth, gradual loss of during de-
velopment, 291
Temperate floras compared, 30, 36,
39; floras, small areas, 77
Temperature - adjustments of
earth's surface. 202
Tertiary period, life of, 235
Tetrabelodon, restoration of, 245
Tetrahelodon angustidens, skeleton
of, 246
Theriomorpha, beast-like reptiles
of Karoo formation, S. Africa,
213
Thompson, E. Seton, on recogni-
tion-marks, 172
Thomson, Prof. J. A., on deter-
minants, 293; on mechanics of
the germ-plasm, 370; on nature's
stern methods, 399
Thought-transference the agent
in life-production and guidance,
425
Thylacoleo carnifex, skull of, 258
Titanotherium rohustum, skeleton
of, 238
Toxodon platensis, skeleton of, 250
TOXODONTIA, 251
Truchycerafiaon, 289
Tkicoxodon, 229
Tkilobites, early and late forms
of, 287
Tkixiuad, flora of, 68
Thopical floras of the world, 43; of
large areas compared, 45; small
areas, 77
Tropical and temperate vegetation
compared, 105
Thopical vegetation, causes of rich-
ness of, 106
Tylor, a., on rate of denudation,
189
Uintatherium ingens, skeleton of,
236; cornutum, skull of, 237
Ungulata, early forms of, 235;
extinct South American, 249
Universe, purpose of the stellar,
299 '
Upheaval produced by contraction,
197
Variation of mind as great as of
body, 114; as shown in curve of
stature. 116; of the various parts
of a bird, 118
Variation of species, 113
Variations, co-ordination of, 275
Variety in nature, purpose of, 300;
the law of the universe, 415;
cause and purpose of, 420
Vegetable products in relation to
man, 350
Vegetation, differences of tropical
and temperate, 105; early, 210
VernoNj Dr. H. M., on variation,
119; on parts of human body
varying independently, 120
Vertebrates, special features in
development of, 291
Vital force. Max Verworu on, 316;
Dr. A. Kerner on, 356
WARiiiNG, Professor Eug., on flora
of Lagoa Santa, 67, 74
Water in relation to life, 394; com-
plex problems of, 395; as prepar-
ing earth for man. 397
Weismann's theorv of germinal se-
lection, 292
Weymouth, abundance of ammon-
ites at. 288
INDEX
441
Wilson, Alexander, on numbers of
passenger pigeons, 125, 126
Winter transformed into summer,
153
Wood, various qualities of, 352
Woodrufffc-Peacock on detailed
floras, 15; on meadow and pas-
ture plants, 17
Woodward. Dr. A. S., on progress-
ive developments of some charac-
ters, 285; on small brains of early
vertebrates, 270
Wulfenia carinthiaca, small range
of, 19
X-RAYS prove use of pain, 411
Zoological regions, species of birds
in, 96
i
i