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Full text of "The world of life; a manifestation of creative power, directive mind and ultimate purpose"



7^f 



THE WORLD OF LIFE 






The senses are the ministers of love, 

The senses are the oracles of truth, 

The senses the interpreters of law, 

The senses the discoverers of fact ; 

They hold their court in beauty and in joy 

On earth and in the spheres where Angels dwell, 

And through the senses God reveals Himself 

And through the senses earth is taught from heaven. 



Born from the darkest age 
Of superstition is that ancient creed 
That matter is the enemy of good, 
Accursed and hateful to the Infinite ; 
For every atom is a living thought, 
Dropped from the meditations of a God, 
Its every essence an immortal love 
Of the incarnate Deity ; and all 
The inmost pulses of material things 
Are mediums for the pulses of His will. 



THE WORLD OF LIFE 

A MANIFESTATION OF 

CREATIVE POWER, DIRECTIVE MIND 

AND ULTIMATE PURPOSE 



BY 



ALFRED RUSSEL WALLACE 

O.M., D.C.L., F.R.S., Etc. 

author of 

"my life: a record of events and opinions," "man's place in the universe," 

"the malay archipelago," "darwinism," " geographical distrihution 

of animals," " natural selection and tropical nature," etc. 



" Every plant, whether beech, lily, or seaweed, has its origin 
in a cell, which does not contain the ulterior product, but which 
is endowed with, or accompanied by a force, which provokes and 
directs the formation of all later developments. Here is the fact, 
or rather the mystery, as to the production of the several species 
with their special organs." 

Althonse de Candolle. 



FIFTH EDITION 



LONDON 

CHAPMAN AND HALL, Limited 

191 i 





All nature is but art unknown to thee : 

All chance, direction which thou canst not see ; 

All discord, harmony not understood ; 

All partial evil, universal good. 



God of the Granite and the Rose ! 

Soul of the Sparrow and the Bee ! 
The mighty tide of Being flows 

Through countless channels, Lord, from Thee. 






PREFACE 

In the present volume I have attempted to summarise and 
complete my half- century of thought and work on the 
Darwinian 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 will 
be of interest to all plant-lovers, and also be not without a 
certain value to botanists. 

Next in importance are three chapters (X., XI., and XII.) 
devoted to a general review of the Geological Record 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 
selection actually at work in continually perfecting that 
wonderful co-adaptation of the most diverse forms of life 
which pervades all nature. Some little-known aspects of 
bird-migration are here discussed, and proof is given of the 
enormous importance of mosquitoes for the very existence 
of a 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. 



vi THE WORLD OF LIFE 

In Chapter IX. I deal with some little-known pheno- 
mena in that hitherto neglected field of enquiry which I 
have termed " Recognition Marks." Besides the obvious 
uses implied by their name, I have shown that they are of 
great importance — perhaps absolutely essential — in the pro- 
cess 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 mark- 
ing have not been developed through their own visual per- 
ceptions, but mainly — perhaps 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 a popular yet critical examination of those 
underlying fundamental 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 — growth and reproduction. 

I first endeavour to show (in Chapter XIV.) by a care- 
ful 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 
Lepidoptera (as easily accessible examples of what is going 
on in every part of the structure of every living thing), the 
absolute necessity for an organising and directive Life- 
Principle in order to account for the very possibility of these 
complex outgrowths. I argue, that they necessarily imply 
first, a Creative Power, which so constituted matter as to 
render these marvels possible ; next, a directive Mind 



PREFACE vii 

which is demanded at every step of what 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 throughout the eons of 
geological time. This Purpose, which alone throws light on 
many of the mysteries of its mode of evolution, 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 
work, and can deduce from them a supreme and over- 
ruling Mind as their necessary cause. 

For those who accept some such view as I have 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 
coincidences. 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, as well as of his advancing civilisation. 

From a consideration of these better-known facts I 
proceed (in Chapter XVII.) 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 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 



viii THE WORLD OF LIFE 

enables us to answer the question — " Is Nature Cruel ? " 
with a decided negative. 

This outline of the varied contents and objects of my 
book, will, 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 dis- 
likes, without any appeal to evidence or to reasoning. This 
is not a method I have adopted in any of my works. 

I have now only to express my thanks to the friends 
and correspondents who have kindly assisted me with 
numerical and other data for various portions of my book ; as 
well as to those publishers and authors who have allowed me 
to use the engravings or photographs with which my book is 
illustrated. These are in every case (I believe) acknowledged 
in the text, or on the various plates and figures. 



Broadstone, Wimborne, 
Nove.?nbtr 1910. 



CONTENTS 

CHAPTER I 

PAGE 

What Life is, and Whence it Comes . . i 

CHAPTER II 
Species — their Numbers, Variety, and Distribution . 1 1 

CHAPTER III 

The Numerical Distribution of British Plants : 

Temperate Floras Compared . . . .22 

CHAPTER IV 

The Tropical Floras of the World . . .40 

CHAPTER V 

The Distribution of Animals . . . .83 

CHAPTER VI 

The Numerical Distribution of Species in Relation to 

Evolution . . . . . -93 

CHAPTER VII 

Heredity, Variation, Increase . . . .101 

ix 



x THE WORLD OF LIFE 

CHAPTER VIII 

PAGE 

Illustrative Cases of Natural Selection and Adapta- 
tion . . . . . . .124 

CHAPTER IX 

The Importance of Recognition-Marks for Evolution. 156 

CHAPTER X 

The Earth's Surface- Changes as the Condition and 

Motive- Power of Organic Evolution . .173 

CHAPTER XI 

The Progressive Development of the Life-World, as 

shown by the Geological Record . . .188 

CHAPTER XII 

Life of the Tertiary Period . . . .219 

CHAPTER XIII 

Some Extensions of Darwin's Theory . . .252 

CHAPTER XIV 

Birds and Insects : as Proofs of an Organising and 

Directive Life-Principle .... 286 ' 

CHAPTER XV 

General Adaptations of Plants, Animals, and Man . 305 

CHAPTER XVI 

The Vegetable Kingdom in its Special Relation to Man 325 



CONTENTS xi 

CHAPTER XVII 

PAGE 

The Mystery of the Cell . . . . -335 



CHAPTER XVIII 

The Elements and Water, in Relation to the Life- 
World . . . . . . .355 



CHAPTER XIX 

Is Nature Cruel? The Purpose and Limitations of 

Pain ....... 3 6 9 



CHAPTER XX 

Infinite Variety the Law of the Universe — Conclu- 
sion . . . . . .385 



INDEX . . . . . . .401 



LIST OF ILLUSTRATIONS 



Fir;. 

i. Forest in Kelantan, Malay Peninsula . 

2. Forest in Perak, Malay Peninsula 

3. Campos of Lagoa Santa, Brazil . 

4. View of Campo Cerrado, Lagoa Santa 

5. View at Lapa Vermelha Rocks, Lagoa Santa 

6. Casselia chamaedrifolia 

7. Andira laurifolia .... 

8. Forest Stream in West Java 

9. Diagram of Curve of Stature 

10. Diagram of Variation 

11. American Bison .... 

12. The Lemming .... 

1 3. Shooting Wild Geese at the Arctic Circle 

14. Geese Migrating .... 

15. Mr. Seebohm's Mosquito Veil . 

16. Watching Grey Plover among Mosquitoes 

17. Ice breaking up, Petchora River 

18. Midsummer on the Tundra 

19. Migratory Birds arriving on the Tundra 

20. Grey Plover, Nest, and Young 

21. The Higher Tundra . 

22. Migration Night at Heligoland 

23. Mimicry of Wasp by a Beetle 

24. Tragclaphus spekei . 

25. Boocercus euryceros . 

26. Gazella grant i . 

27. Gazella ivalleti 

28. Strepsiceros kudu 

Xlll 



46 

47 
64 
66 
66 
68 
69 

75 
108 

1 10 

115 
120 

136 
137 
138 

•39 
141 

142 

143 
144 

147 
150 
158 
161 
161 
161 
161 
161 



XIV 



THE WORLD OF LIFE 



FIG. 
29. 

3°- 
31. 

32. 

33- 
34- 
35- 
36. 
37- 
38. 

39- 
40. 
41. 

42. 

43- 
44. 

45- 
46. 

47- 
48. 
49. 
50. 

5i- 

52. 

53- 
54- 

55- 
56. 

57- 
58. 

59- 
60. 
61. 
62. 

63. 
64. 

65. 



Strepsiceros imberbis 

Bubalis jacksoni 

ALpyceros melampus 

Cobus leche 

Cobus defassa . 

Cobus maria 

Oryx gaze Ha . 

CEdicnemus grallarius 

CEdicnemus mag7iirostris 

CEdicnemus recurvirostris 

Thelodus scoticus 

Pteraspis rostrata 

Cephalaspis murchisoni 

Protocercal Tail of Primitive Fish 

Heterocercal Tail 

Homocercal Tail 

Pariasaurus bainii . 

Skull of Dicynodo7i lacerticeps 

Skull of AHlusaurus felhius 

Skull of Inostransevia 

Restoration of Dimetrodon 

Skeleton of Iguanodon bemissartensis 

Restoration of Iguanodon . 

Skull of Iguanodon bemissartensis 

Skeleton of Scelidosaurus harrisoni 

Skull of Sterrolophus flabellatus 

Restoration of Stegosaurus 

Skeleton of Brontosaurus excelsus 

Skeleton of Diplodocus carnegii . 

Skull of Diplodocus . 

Skull of Ceratosaurus nasicomis 

Outline and Skeleton of I lesiosaurus macrocephalus 

Outline and Skeleton of Ichthyosaurus communis 

Bones of Paddles of Ichthyosaurus 

Skeleton of Pterodactylus spectabilis . 

Restoration of Rhamphorhynchus phyllurus 

Skeleton of Pteranodon occidentalis 



ILLUSTRATIONS 



xv 



FIG. 

66. Skull of Pteranodon longiceps . 

67. Jaw of Phascolotherium bucklandi 

68. Jaw and Teeth of Spalacothcrium tricuspidens 

69. Jaw of Triconodon mordax 

70. Drawing of Archa?opteryx tnacrura . 

71. Skull of Archceopteryx siemensi 

72. Skeleton of Phenacodus primcevus 

73. Skeleton of Uintatherhim ingens 

74. Skull of Uintatherhim comutum 

75. Skeleton of Titanotherium robustum 

76. Skull of Arsinoitherium zitteli . 

77. Skeleton of JTycznodon cruentus 

78. Skeleton of Hyopotamns brachyrhynchus . 

79. Outline and Skeleton of Anoplotherium commune 

80. Outline Restoration of PalcEotherium magnum 

8 1 . Skull of Moeritherium lyonsi . 

82. Skulls of Ancestral Elephants . 

83. Skeleton of Tetrabelodon angustidens 

84. Restoration of Tetrabelodon angustidens 

85. Skeleton of Mastodon americanus 

86. Skeleton of Elephas primigenius 

87. Skeleton of Toxodon platens is . 

88. Skeleton of Glyptodon clavipes 

89. Restoration of Megatherium giganteum 

90. Skeleton and Outline of Mylodon robustus 

91. Skeleton of Scelidotherium leptocephalum 

92. Skull of Diprotodon australis . 

93. Skull of Thylacoleo carnifex 

94. Skull of Macharodus neogceus . 

95. Skeleton of Cervus giganleus . 

96. Conocoryphe sultzeri (an early Trilobite) 

97. Paradoxides bohemicus (an early Trilobite) 

98. Acidaspis dufresnoyi (a late Trilobite) 

99. Ceratites nodosus (early Ammonite) . 

100. Trachyceras aon (early Ammonite) . 

101. Crioceras emerici (Cretaceous Ammonite) 

102. Heteroceras emerici (Cretaceous Ammonite) 



PAGE 

211 

213 
213 
213 
214 

215 

219 
220 

221 

222 
223 
225 
226 
227 
227 
228 
229 
230 
230 
231 
232 

234 
236 

237 
237 
238 
240 
240 
266 
266 
267 
267 
267 
268 
268 
268 
268 



XVI 



THE WORLD OF LIFE 



103. Macroscaphites ivanii (Cretaceous Ammonite) . 

104. Hamites rotundus (Cretaceous Ammonite) 

105. Ptychoceras emericianum (Cretaceous Ammonite) 

106. Ancyloceras matheronianutn (Gault Ammonite) . 

107. Head of Babirusa ...... 

1 08. Perspective view of part of a Wing-feather 

109. Oblique section showing how the Barbules hook together 

1 10. Diagram of Nuclear Division .... 





PAGE 
269 




269 




269 




269 




275 




289 


:her 


289 


• 


343 



CHAPTER I 

WHAT LIFE IS, AND 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 
especially 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 con- 
trast 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 out- 
wardly, 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 when both 
externally and internally he could find no resemblance 
whatever to his own body; to crabs and winged insects, to 

l B 



2 THE WORLD OF LIFE 

land-shells and sea-shells, and ultimately to everything which 
by moving and feeding, by growing 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 well 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 endless 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 ; while the idea 
that there is in them any essential feature connecting them 
with animals and entitling them to be classed all together 
as members of the great world of life would only arise at a 
considerably later stage of development. 

It is, in fact, only in recent times that the very close 
resemblance of plants and animals has been generally 
recognised. The basis of the structure of both is the almost 
indistinguishable cell ; both grow from germs ; both have a 
varied life-period from a few months to a maximum of a 
few hundreds of years ; 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. 

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 



i WHAT LIFE IS 3 

matter, while they give no clear indications of the possession 
of sensation or voluntary 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 pre- 
sented 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 Encyclopaedia) summed it up in three 
words — " Continuity, Rhythm, and Freedom," — true, perhaps, 
but not explanatory ; while Herbert Spencer declared it to 
be — " the definite combination of heterogeneous changes, 
both simultaneous and successive, in correspondence with 
external co-existences and sequences." This is so technical 
and abstract as to be unintelligible to ordinary readers. 

The following attempt at a tolerably complete definition 
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 in a continuous state of decay 
and repair by internal circulation of fluids and gases ; they 
reproduce their like, go through various phases of youth, 



4 THE WORLD OF LIFE 

maturity, and age, die, and quickly decompose into their con- 
stituent 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, however, 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 organisa- 
tion 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 un- 
scientific — to be, in fact, an indication of something akin to, 
if not actually constituting, an old-fashioned superstition. 
That such a view is not uncommon may be shown by a few 
extracts from scientific 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- 
Reymond 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 Riddle of the Universe, 
p. 65, translated by Joseph M'Cabe). 



WHAT LIFE IS 5 

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 
meaning if not in actual words. In the first, he reduces 
consciousness 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 con- 
ceives " the elementary 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 
operative 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 thinking substance, are the two fundamental attributes, or 
principal properties, of the all-embracing essence of the world, the 
universal substance " (p. 8). 

Here we have yet another contradiction — that the 
thinking infinite substance is unconscious ! This leads to 
his theory of the "cell-soul," which is the origin of all 
consciousness, but which is itself unconscious. This he 
reiterates emphatically. He tells us that at a certain grade 
of organisation " consciousness has been gradually evolved 
from the psychic reflex activity, and now conscious voluntary 
action appears" (p. 41). Along with these strange con- 
ceptions, which really explain nothing, he propounds his " Law 
of Substance " as the one great foundation of the universe. 
This is merely another name for " persistence of force " or 
" conservation of energy," yet at the end . of the chapter 
expounding it he claims that, " in a negative way, it rules 
out the three central dogmas of metaphysics — God, freedom, 
and immortality " (p. 83). A little further on he again states 
his position thus : 



6 THE WORLD OF LIFE 

" 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 
concludes : 

" 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 law of substance" 
(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, emphasising 
its negative aspect, the non-existence of any supernatural deity" 
(P- 103). 

These vague and often incomprehensible assertions are 
interspersed 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 
assertive 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 



WHAT LIFE IS 7 

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 declares that " matter," or 
the material universe, is infinite, as is the "ether," and that 
together they fill infinite space, and that both are " eternal " 
and both " alive." None of these things can possibly be 
known, 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 possibilities of nature 
leads us to the conclusion that in infinite space there may 
be other universes besides ours ; but if so, they may possibly 
be different from ours — not of matter and ether only. To 
assert the contrary, as Haeckel 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 extinction. 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 promise of a future life, and which 
have in our own day found a large mass of evidence justify- 
ing that belief 

With Professor Haeckel's 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 



8 THE WORLD OF LIFE chap. 

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 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 
Professor 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 under a special term. In his Introduction to the 
Classification of Animals (1869), in his account of the 
Rhizopoda (the group including the Amoebae and Foramini- 
fera), 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 animal 
life there is absolutely nothing worthy of the name of organisation 
to be discovered by the microscopist, though assisted by the 
beautiful instruments that are now constructed. ... It is structure- 
less 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 extra- 
ordinary 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 mathe- 
matically-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). 



i WHAT LIFE IS 9 

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 lifeless. " But when they are brought 
together under certain conditions they give rise to the still 
more complex body, protoplasm, and this protoplasm 
exhibits the phenomena of life " (p. 52). Then follows an 
exposition of the well-known argument as to water and 
crystals being produced by the " properties " of their con- 
stituent elements, with this conclusion : 

" Is the case any way changed when carbonic acid, water, and 
nitrogenous salts disappear, and in their place, under the influetice 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 statement ; and these are of 
fundamental importance considering the tremendous con- 
clusion he goes on to draw from them — " that the thoughts 
to which I am now giving utterance are the expression of 
molecular 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 terminology 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 expression 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 
everywhere manifested in the growth of living things. 



10 



THE WORLD OF LIFE 



CHAP. I 



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 by a very different method. I 
shall 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 THEIR NUMBERS, VARIETY, 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 
presence in ample quantity we depend for our daily food 
and continued existence, we have perpetually to discuss and 
to deal with those entities technically known as species, but 
which are ordinarily referred to as sorts or kinds of plants 
and animals. When we ask how many kinds of deer or of 
thrushes, of trout or of butterflies, inhabit Britain, we 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 naturalists, 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 recognised, 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 formerly supposed ; 
yet the great mass of them are stable within very narrow 
limits, while 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 production of 

ll 



12 THE WORLD OF LIFE 

new species — appears to be going on before our eyes. The 
reader may therefore rest assured that there is no mystery 
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 
necessarily so prominent. The reason why species is the 
better term is because kind 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 kind in this latter sense, all ambiguity would be 
avoided. 

Few 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-adaptation 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 World Species 

The first important group of facts which we have to 
consider is that which relates to the number of existing 
species of the two 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 group 
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 
everywhere, others are scarce and only occur in small 
numbers even in the places where alone they are usually 






II 



DISTRIBUTION OF SPECIES 13 



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 peculiarities as soil 
and moisture, exposure to sun or wind, the presence 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 vegetation 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 been 
brought by the wind or by birds, or have lain dormant in 
the ground) ; but in the second and third years these change 
their proportions, 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 railway banks, of which I 
have given several examples in my Island Life (p. 513, 
footnote). All these phenomena, and many others which 



14 THE WORLD OF LIFE 

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 Woodruffe- 
Peacock 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 (i) 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 
uncommon yet widely distributed plant, he has sent me a 
copy of his paper on the Black Horehound (Ballota nigra), 
a species not uncommon over much of Central Europe, but 
scattered over Central and Southern Britain only in a few 
favourable localities. 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 : 

" When 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 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 



II 



DISTRIBUTION OF SPECIES 15 



by cows, when the much-loved Lamium album (the white dead- 
nettle) is left untouched ; but it would seem 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 requirements, 
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. 

Two 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 according as 
these portions were grazed by farm stock or regularly 
mown for hay. 

Again, Mr. Woodruffe-Peacock states, that the assem- 
blage 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. 



16 THE WORLD OF LIFE chap. 

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 species. These are mostly rare, and are very often 
not truly British 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 relations 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 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 advisable 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 



II 



DISTRIBUTION OF SPECIES 17 



botanical works in existence, his Geographie botanique 
raisonnee, in two thick volumes. 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 influence their distribu- 
tion, 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 altitude, latitude, aspect, 
humidity, geological and mineralogical causes, both in their 
direct and indirect action, and as applying to cultivated as 
well as wild 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 world, and 
under various geographical conditions, and thus arrives at 
the causes of great extension of certain species from west to 
east in the north temperate zone, or along sea-shores or 
river-banks in the tropics ; while the normal area is 
considered 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 

i of the globe. Further, in certain Families (usually called 
Natural 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 

C 



18 THE WORLD OF LIFE 



CHAP. 



rotundi 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 perhaps the nearest of any 
known plant to being truly cosmopolitan. 

By a laborious comparison the author arrives at the 
conclusion that the average area occupied by the species of 
flowering plants is T Jxr tn P art °f tne whole land surface of 
the globe. But the area varies enormously in different parts 
of the world. Thus, in the whole Russian Empire, species 
have a mean area of ^th the land surface, owing to the fact 
that so many range east and west over a large part of 
Europe and North Asia ; while in South Africa the mean 
range is only ^0o tn °^ tnat sur f ace > which expresses the 
fact of the extreme richness of the latter flora, many of the 
species composing which have extremely restricted ranges. 
He also reaches the conclusion that in passing from the pole 
to the equator the mean areas of the species become smaller. 
A few examples of very limited areas are the following : — 
Several species of heaths are found only on Table Mountain, 
Cape of Good Hope ; Campanula isophylla grows only on 
one promontory of the coast of Genoa ; the beautiful Alpine 
Gromwell {Lithospermum Gastoni), on one cliff in the 
Pyrenees ; Wulfenia Carinthiaca, on one mountain slope in 
Carinthia ; 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 dis- 
tinguished by the possession of a considerable proportion of 
peculiar species of plants. These regions are of greatly 
varying extent, from No. 18, comprising the whole of 
Northern Asia, to No. 10, limited to the small island of 
Tristan d'Acunha in the South Atlantic. 

The list is as follows : — 

A. De Candolle's Botanical Regions 



i. 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. 



II 



DISTRIBUTION OF SPECIES 



19 



'"" ! 



9- 


South Africa. 


29. 


Australia, New Zealand. 


IO. 


Tristan d'Acunha. 


30. 


Fiji to Marquesas. 


1 1. 


Islands of Kerguelen, St. Paul, 


31. 


Mariannes, Carolines. 




etc. 


32. 


Sandwich Islands. 


12. 


Madagascar, etc. 


33- 


N.W. America. 


13- 


Mozambique, Zanzibar. 


34- 


Canada and United States. 


14. 


Abyssinia to Egypt. 


35- 


Texas, California, Mexico. 


15- 


Persia, Euphrates. 


36. 


West India Islands. 


16. 


Caucasus, Armenia. 


37. 


Venezuela. 


17. 


Tartary east of Caspian. 


38. 


Columbia. 


18. 


Siberia, Ural to Kamschatka, 


39. 


Peru. 




Lake Aral. 


40. 


Galapagos. 


19- 


Asia Central. 


4i. 


Bolivia and Andes. 


20. 


Afghanistan to Indus. 


42. 


Guayanas. 


21. 


Nepal to Bhutan. 


43- 


Amazonia. 


22. 


China, Japan. 


44- 


Brazil N.E. 


23- 


Philippines. 


45- 


,, W., Paraguay. 


24. 


Siam, Cochin China. 


46. 


„ S.E. 


25. 


Burma and Assam. 


47- 


Uruguay, La Plata. 


26. 


Bengal, Ganges. 


48. 


Chile, Juan Fernandez. 


27. 


Peninsular India, Ceylon. 


49- 


Patagonia, Falkland Islands 


28. 


Malacca, N. Ireland. 


50. 


The Antarctic Archipelago. 



By an extensive comparison of floras all over the world 
it is found that less than five per cent of the total of the 
known species are found in more than two of these regions. 
Families 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 
dispersal 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 dis- 
persal, either by the wind or by animals. But he also points 
out, what is now well known to botanists, that the species 
of Compositae 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 dis- 



20 THE WORLD OF LIFE chap. 

tributed 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 purpose of securing 
ample means of reproduction within 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 general 
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 
studying 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 con- 
sists in the characterisation of the vegetation of each region 
or district by the proportionate abundance in species belong- 
ing to the different natural orders. 

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 1 1 
largest natural orders comprise half the whole number of 
species. In British Guiana 12 orders are required, and in 
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 preponderant 
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 Leguminosae usually 
come first, though sometimes Orchids are most abundant ; 
in temperate regions the Composites or the Grasses ; and in 
the Arctic, Grasses, followed by Cruciferae and Saxifrages. 






DISTRIBUTION OF SPECIES 



21 



,A few of the tables constructed by De Candolle are given 
as examples. 

British Guiana (Schomburgh) 

3254 species 

469 species 

2 14 

176 



Leguminosae 
Orchideae . 
Rubiaceae . 
Melastomaceae 



126 



)5 



The Andes of New Grenada (Humboldt) 
1 04 1 species 



Leguminosae 


65 


»> 


Rubiaceae .... 


49 


>J 


Gramineae .... 


42 


J> 


Orchideae .... 


41 


■>■> 



Australia and Tasmania (R. Brown) 

4200 species 

Leguminosae Cyperaceae 

Euphorbiaceae Gramineas 

Compositae Myrtaceae 

Orchideae Proteaceae 







Iceland. 


402 species 




r. 


Cyperaceae . 


47 


7. Saxifrageae 


• 15 


2. 


Gramineas . 


45 


8. Rosacea? . 


15 


3- 


Compositae . 


24 


9. Ericaceae . 


12 


4- 


Caryophylleae 


23 


10. Juncaceas . 


12 


5- 


Cruciferae 


21 


1 1. Ranunculaceae 


1 1 


6. 


Amentaceas . 


20 


12. Polygoneae 


1 1 



As a short general conclusion De Candolle says : 

The Leguminosae . . . dislike cold. 

The Composites .... dislike cold and wet. 

The Grasses dislike drought. 

Other examples will be given when discussing the com- 
parative relations of the various temperate and tropical floras 
of the world. 



CHAPTER III 

THE NUMERICAL DISTRIBUTION OF BRITISH PLANTS : 
TEMPERATE FLORAS COMPARED 

Proceeding from the more to the less familiar regions we 
will begin with a few of the facts as to the flora of our own 
country. Partly owing to its insular character, and also 
because it has few lofty mountains or extensive forests, the 
number of species of flowering plants is somewhat (but not 
much) below that of most continental countries of equal area. 
It contains about 1 800 species, as a rough mean between 
the estimates of different botanists. 1 It may seem curious 
that there should be any such difference of opinion, but one 
of the facts that have always 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 intermediate forms. Again, 
when these varieties are cultivated, and especially 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 habita- 
tions, which are supposed to have been originally introduced, 
either purposely or accidentally, from foreign countries. 

1 In all the tables and comparisons of " Floras" in this work, unless where 
ferns are specially noted, flowering plants only are intended, even when the term 
'* plants " is used. 

22 



CHAP. Ill 



TEMPERATE FLORAS 



23 



Such are the wild Larkspur and Monkshood, the 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 any of the text-books or local floras. 

The chief differences 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 Hawkweeds (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. 


10th Ed., 1908. 


Rubus 
Hieracium . 
Euphrasia . 
Rhinanthus. 


54 species 
48 „ 

1 „ 

1 » 


1 16 species 
133 „ 
15 „ 
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 Linnaeus 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 the great 
majority of the species of plants as well as of animals offer 
little difficulty, and present few fixed varieties (though 
abundance of variation), so that for general comparisons the 
figures obtainable are very fair approximations, and give us 
interesting and valuable information. 

About one-third of the total number of our species of 
wild flowering plants belong to what the late Mr. H. C. Watson 






24 THE WORLD OF LIFE chap. 

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, 
Nettle, and a host of others. Another group is abundant 
in England, but absent from the Highlands or from Scotland 
generally, such as the Dwarf Gorse and Yellow Dead-Nettie. 
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 N. 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, Simethus bicolor, 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 Gentia?ia 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 
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 altogether 
ceases to exist. The rarity of a species may thus be 
considered as an indication of approaching extinction. 



Ill 



TEMPERATE FLORAS 



25 



Numerical Distribution of Plants in 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 5 5 
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 


1056 


Cornwall . 






1357 


I 140 


Dorsetshire 






980 


IOIO 


Essex 






1533 


IOIO 


Glamorganshire 






790 


950 


Hampshire 






1612 


1 150 


Herefordshire . 






840 


865 


Hertfordshire . 






636 


890 


Kent 






1519 


1 120 


Lincolnshire 






2638 


1200 


Middlesex 






233 


835 


West Yorkshire 






2658 


995 


Mean of the 12 counties 


I 198 


1026 


Great Britain . 






87,500 


1800 



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 represented in it. This 
variety of soil seems to be much more important than 
diversity of surface due to altitude, so that our lowland 



26 



THE WORLD OF LIFE 



CHAP. 



counties are quite as rich as those which are hilly or 
mountainous. Again, we see that, within moderate limits, 
greater area has little influence 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 
surface 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 10 10 species. 

An equally remarkable instance was given by Mr. H. 
C. Watson fifty years ago, and no doubt from his own 
observations, as he resided in the county. 



Large and Small Areas. 


Area, Sq. Miles. 


Species. 


Surrey ...... 

An area in Surrey of . 

)> )> ... 
,, at Thames Ditton, Surrey . 


760 

60 

10 

I 


840 
660 
600 
400 









Here we see that 10 square miles contained nearly as 
many species as 60, and nearly two-thirds the number in 
760 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 i6|- feet square (or 1 perch) would usually have 20 to 30 
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 



in TEMPERATE FLORAS 27 

of turf 3 feet by 4, at Down in Kent, Mr. Darwin found 20 
species of flowering plants growing. 

These facts of the distribution of plants in our own 
islands 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, 1 o 
square miles may show almost as much variety in its plant- 
life as an adjacent area of 60 square miles, and that a 
single square mile may sometimes contain half the number 
of species found 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, although widespread, are thinly 
scattered in favourable situations, 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- 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 
depends mainly on these two factors, and especially on the 



28 THE WORLD OF LIFE 

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 
moisture 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 extending 
to beyond the northern tropic, as on the flanks of the 
Himalayas in north-eastern India, where the monsoon winds 
carry 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 
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) 1 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 1 8 70) was, respectively, 
930, 1 148, and 1230. At the same period the total of 
Great Britain was 1425 species. These figures are all 
obtained 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 decidedly less rich in species than Mid- 

1 Wales is omitted in order to make the three divisions more equal, and con- 
trasted in latitude only. 



Ill 



TEMPERATE FLORAS 



29 



Britain, while both are less rich than South Britain, with its 
more uniform surface, but favoured with a more southern 
climate. 

The following table shows these facts more distinctly : — 



Effects of Latitude. 


Area, 
Square Miles. 


No. of 
Species. 


North Britain ..... 
Mid-Britain, Lowlands south to Stafford -\ 
and Leicester / 
South Britain (Wales excluded) . 


22,325 
26,550 
31.050 


930 
I 148 
1230 



The above figures have been kindly extracted from 
Watson'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. 



Floras of Europe, showing Influence of Latitude 



Countries. 


Area, 
Square Miles. 


No. of 
Species. 


Authorities. 




Europe . . . 


3,850,000 


9500 


Nyman 




Lapland . 


150,000 


500 


A. De Candolle 




Scandinavia and"\ 
Denmark . J 










456,000 


1677 


.) 




Sweden 


173,000 


I 165 


)> 




Britain 


87,500 


i860 


Lond. Cat., 1895 




Germany 


208,000 


2547 


Garche, 1908 




Switzerland . 


16,000 


2454 


Schinz and Kellar, 


1908 


France 


204,000 


4260 


Coste, 1906 




Italy . . . . 


91,400 


4350 


Beccari 




Sardinia . 


9,300 


1770 


). 




Sicily . 


9,940 


2070 


?> 





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 by local conditions 
and by allowing something for differences of area. Sweden 
is so much poorer than Britain, owing to its having been 



30 



THE WORLD OF LIFE 



CHAP. 



completely ice-clad during the glacial epoch, while much of 
southern Britain was free. Germany is poorer than France, 
partly on account of its severer continental climate, but also 
owing to France 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 western 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 advan- 
tages of a similar kind, and its slight superiority to France, 
with less than half the area, is about what we should expect. 
It well illustrates the fact, already ascertained, that difference 
of area within moderate limits is of far less importance than 
comparatively slight advantages in soil and climate. 

Turning now to North America, the following figures 
from the latest authorities have been supplied by my friend 
Mr. T. D. A. Cockerell :— 



Effect of Latitude. 



Area, 

Square Miles. 



Montana and 
stone Park . 
Nebraska 
Colorado 
California 



Yellow-" 



No. of 
Species. 



1934 



I 50,000 

118,000 1478 

104,000 2872 

158,000 2700 

Two subdivisions of the eastern United States show well the effects 

of latitude. 



Remarks. 



Data in 1900 
1898 



» 
»> 



1900 
recent 



Central and north-east' 
States — Michigan to 
Virginia, Kentucky 

South-east United States . 



736,000 
630,000 



3298 
6321 



Recent estimate 



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 France, 



Ill 



TEMPERATE FLORAS 31 



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 by 
I 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 corresponding latitudes of North 
America ; and perhaps the long persistence of such con- 
ditions 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 
northern hemisphere. The great work of Boissier, Flora 
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 intermingled with luxuriant valleys 
and plains, and almost tropically warm in its southern portion. 
So much of it is difficult of access, however, that the collec- 
tions hitherto made must fall far short of being complete. 
Its extreme richness in certain groups of plants is shown by 
the fact that Boissier describes 757 species of Astragalus 
or Milk-vetch, a genus of dwarf plants spread over the 
whole 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. Hemsley of the Kew Herbarium) 
is China and Corea, occupying a little more than i|- million 
square miles. The enumeration, completed in 1905, shows 
8200 species of flowering plants actually described. But 
as large portions of this area have never been visited by 
botanists, and as new species were still flowing in rapidly at 



32 THE WORLD OF LIFE 

the close of the enumeration, there can be little doubt that 
the total will reach, before many years have elapsed, 10,000 
or perhaps 1 2,000 species. It is, moreover, an area that 
is especially rich in trees and shrubs, and as these are less 
collected 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 probably better known, has about 4000 species in 
less than one-tenth the area, and is thus a little richer than 
France. It agrees, however, very closely with the Western 
Himalayas as estimated by Sir J. D. Hooker. 

Coming to the southern hemisphere, we find several 
examples 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, 
New 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 Region, 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 by 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 



Ill 



TEMPERATE FLORAS 



33 



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 
might have included the degradation of lofty mountains. 
It would 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. 


Area, 
Square Miles. 


No. of 
Species. 


Authority. 


S.E. United \ 
States / 


630,000 


6,321 


T. D. A. Cockerell 


J 

Mediterranean . 


550,000 


7,000 


Tchikatcheff 


Greece to \ 
Afghanistan / 






[Boissier, Flora Orien- 
\ talis, 1880 


2,000,000 


I 1,876 


China and Corea 


1,500,000 


8,200 


Hemsley, 1905 


Japan 


I 50,000 


4,000 


Hayati, 1908 


Himalayas, West 


I 50,000 


4,000 


Hooker, 1906 


Algeria 


I 50,000 


2,93° 


Matthews, 1880 




Southet 


■71 Hemisphei 


e 


Chile . 


250,000 


5,200 


■ • • 


N.S. Wales 


310,700 


3,105 


Miilier 


W. Australia 


? 90,000 


3,242 


f ,, (tropics and 

\ deserts omitted) 


Victoria 


88,000 


1,830 


Miilier 


Tasmania . 


26,380 


965 


)5 


New Zealand 


103,650 


1,474 


Cheeseman, 1906 


South Africa 


1,000,000 


13,000 


Thomer's Census 


The Cape Region 


30,000 


4,500 


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 

D 



34 



THE WORLD OF LIFE 



CHAP. 



them in order of latitude, from north to south, so as to show 
still more distinctly the influence of climate. Each main 
division of the globe will be considered separately for 
convenience of reference, and we begin with Europe, for 
which materials are the most accessible, though still far from 
abundant. 

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 





Area, 


No. of 




Locality. 


Sq. Miles. 


Species. 


Remarks. 


Harjedal (Sweden), lat. 6i°-64° 


5375 


606 


Birger. 1908 


Malvern Hills 


120 


802 


De Candolle 


Hertford (near) 




80 


8lO 


>) 


Strasburg, lat. 48 jL° 




120 


960 


>> 


0) 


'Schaffhausen 




114 


I 220 


H. H. Field 


J 


Thurgau 




381 


IO06 


55 


7s - 


Basel . . . . 




163 


I I 17 


>> 


k 


Zurich . 




666 


II51 


>5 


r 


St. Gallen 




779 


1295 


?> 


! a fSchwyz, Uri, Underwalde 
•£-! Glarus . 
< I Uri 


n 


950 


1352 


)) 




267 


I IOO 


)) 




415 


I 160 


)) 


c5 j-Grisons . 
5 J valais, 4 6±° . 
I53 iTicino, 46^° . 




2773 


1550 


5) 




2027 


1752 


5' 




1088 


1504 


11 


Ofengebietes, Grisons 




86 


797 


Lat. 46°4o' 


Vallee de Joux, Jura 




100 


823 


Lat. 46°4o' 


Bergunerstocke, Engadine 


47 


873 


Lat. 46°3o' 


Poschiavo, S. of Bernina Pass . 


92 


1200 


„ 46°2o' 


Euganean Hills, Padua . 


795 


1400 


» 45°3°' 


Susa, Piedmont (Beccari) 


540 


2203 


,, 45°i°' 


Ferrara, Valley of Po (Beccari) 


1012 


794 


» 44°5°' 


Mytilene (Lesbos) (Candargy) . 


675 

1 


1249 


,, 39°°°' 



(I am indebted to Mr. Herbert H. Field for all the data 
in this table, except where otherwise stated. They are from 



Ill 



TEMPERATE FLORAS 35 



the original authorities, and he has kindly brought them 
up to date as far as possible, so that they may be fairly 
comparable.) 

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 ioo miles forming its southern boundary, 
and the Bernese Alps its northern. But Schaffhausen geo- 
1 graphically connects eastern France with western Germany, 
and partakes of the rich flora of both countries. This table 
i 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 Hertford ! Switzerland, though so very 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 
i of our area, has a greater number of species by one-third, 
that superiority is, as a rule, reproduced in its subdivisions. 
Susa, in Piedmont, with its fertile valleys and snowy Alps, 
has by far the richest flora of the whole series, due to its 
warm 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 farther on, there are indications that the high 
alpine flora really partakes of that poverty which appertains 
to high 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 



36 



THE WORLD OF LIFE 



CHAP. 



which is to some extent deceptive, and this is increased by 
the fact that whole 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 very widely 
scattered ; but they serve to illustrate the fact already dwelt 
upon, that the differences of species-population in fairly com- 
parable areas approach to a general uniformity all over 
the world. 



Extra-European Temperate Floras — Small Areas 



Lat. 


Country. 


Area, 

Sq. Miles. 


No. of 
Species. 


Remarks. 




Nor tli America. 








40° N. 


Boulder Co., Colorado . 


75i 


I200 


Cockerell 


39° N. 


Washington, D.C. . 
Japan. 


108 


922 


Ward 


37° N. 


Mount Nikko 


360 


800 


Hayati 


37° N. 


Mount Fujiyama . 
South Africa. 


520 


73° 


>> 


35' S. 


Cape Peninsula 

Australia. 


197 


1750 


Bolus 


35° S. 


Illawarra, N.S.W. . 


200 


829 


A. G. Hamilton 


34° S. 


Cumberland Co., N.S.W. 


1400 


1213 


W. Woolls 


32rs. 


Mudgee (Wellington Co.) 


600 


631 


A. G. Hamilton 


27 rs. 


Brisbane, Q. . 

North hidia. 


800 


1283 


Jas. Wedd 


27|°N. 


Temperate Sikhim . 


1800 


2000 


Hooker 






in TEMPERATE FLORAS 37 

Boulder County is probably one of the most favourably 
situated areas in the United States. It is only 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- 
hausen, somewhat similarly situated, but at a higher latitude. 
The two mountain areas in Japan, which Mr. Hayati 
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 
ombined effect of altitude and insularity in diminishing 
pecies-production, the lower parts of these Japan mountains 
eing highly cultivated. 

In the southern hemisphere we come first to the Cape 

eninsula, as limited by Mr. Bolus, and often thought to 

e the richest area of its size in the world. There are 80 

pecies of heaths and nearly 100 species of orchises in this 

mall tract only a little larger than the Isle of Wight. No 

ther similar area in the temperate zone approaches it, 

though it is possible that an equally rich area of the same 

xtent might be found in temperate Sikhim, where several 

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 1 8 10 Robert Brown made known the extreme interest 



38 THE WORLD OF LIFE 

of the Australian flora, both from its numerous hitherto 
unknown 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 New South Wales, Victoria, or Tasmania. 
Cumberland County, which contains Sydney and the cele- 
brated 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, exclusive 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. Fitzgerald, the authority on the 
Orchids of Australia, that " within the radius of a mile " he 
had gathered 62 species of Orchids ; on which Mr. Bolus 
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 beyond the city and 
suburbs of Sydney, in which case it might be an area of 
from 10 to 20 square miles. Or it might mean a picked 
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 River, to the north-west 
of Sydney, and he here obtained 59 species of Orchids out 
of a total of 6 1 8 flowering plants. The sequence of the 
first eight orders in number of species is as follows : — 

1. Orchideae • • 59 5- Compositse . . 32 

2. Myrtacese . . 55 6. Gramineae . . 31 

3. Leguminosoe . . 53 7. Cyperaceae . . 30 

4. Proteaceae . . 35 8. Epacrideae . . 25 



TEMPERATE FLORAS 39 

In New South Wales, as a whole, Leguminosae 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 approxi- 
mately comparable areas, between these two groups of 
warm - temperate floras is fairly well marked throughout, 
there being, with few exceptions, a decided preponderance 
in the southern hemisphere. South Africa is undoubtedly 
richer than China, though its area is less ; and perhaps than 
the oriental region of Boissier ; while Chile compares 
favourably with Japan or the Western 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 
expanding ; while those in the south have almost certainly 
been far more extensive, and in later geological time have 
been contracting, and thus crowding many species together, 
as already explained. 



CHAPTER IV 

THE TROPICAL FLORAS OF THE WORLD 

ALTHOUGH the idea of the tropics is always associated with 
that of a grand development 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 
erratic distribution of rainfall, and this again is dependent 
on the winds, the ocean currents, and the distribution and 
elevation 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 than 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 the 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 

40 



chap, iv TROPICAL FLORAS 41 

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 
temperate 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 Chile, whence crossing the Andes it 
stretches south-eastward into Patagonia. Even more extra- 
ordinary 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 
deserts, 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 
rainfall, 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, together with herbaceous and bulbous 
plants which cover the ground only during the season of 
periodical rains, as will be shown later on. 



42 



THE WORLD OF LIFE 



CHAP. 



Tropical Floras — Large Areas 



Country. 


Area, 
Square Miles. 


No. of 
Species. 


Authority. 


British India 




1,300,000 


17,000 


Sir J. D. Hooker 


The Indian Peninsula 




500,000 


4,500 


Hooker 


Burma . 




172,000 


6,000 


,» 


Indo-China . 




225,000 


7,000 


Gagnepain 


Malay Peninsula . 




35,000 


5,IOO 


Gamble 


Ceylon . 




25,000 


2,800 


Hooker 


Java 




50,000 


4,000 ? 


Koorders 


Philippines 




1 15,000 


4,656 


Merrill 


New Guinea . 




310,000 


6,000 


Lauterbach 


Queensland . 


• 


668,000 


4,454 


Bailey 


Tropical Africa south 
Sahara 


J 


6,500,000 


18,300 


Thonner's Census 


Madagascar and MasO 
carenes . . J 


229,000 


5,95o 


Thonner 


Central America and) 
Mexico . . / 


910 OOO 


12,000 


Hemsley 


Nicaragua to Panama 


. 


80,000 


3,000 


,, 


Brazil . 


, 


3,200,000 


22,800 


Martius 


Trinidad 


. 


1,750 


1,967 


Hart 1 


Jamaica 


• 


4,200 


2,720 


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, New 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 
certainly surpass those of Africa, with three times their 
tropical area, and may approach, though I do not think they 

1 Mr. W. E. Broadway, who has collected in the island, informs me that 
some hundreds of species remain to be discovered in Trinidad. 



IV 



TROPICAL FLORAS 43 



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 botanic- 
ally, 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 remains 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 abounding riches of Burma and Indo-China ; yet it 
possesses areas, especially in the Western Ghats and the 
Nilgiris, of great botanical richness and beauty, much of 
which is still inadequately explored. Arid conditions pre- 
vail over much of its surface, both in the north and in the 
central plains, but these are interspersed with 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, Umbelliferae, Labiatae, and Boraginese, and a 
corresponding poverty in Melastomaceae, Gesneraceae, Myr- 
taceae, Palms, and other more peculiarly tropical orders. 

Ceylon, though so closely connected with the peninsula, 
has 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 Malayan 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 



44 



THE WORLD OF LIFE 



CHAP. 



of the world (p. 42) 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 Indo-China are much less known than Penin- 
sular India, yet in a smaller area each has a considerably 
larger 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 following table of the chief natural orders is 
taken from Mr. Hemsley's Introduction to the Flora of 
Mexico and Central America : — 



British India (17,000 species) 



I. 


Orchideaa 


1060 


7- 


Compositas 


598 


2_ 


Leguminosas . 


831 


8. 


Cyperaceae 


385 


<5 
J' 


Gramineas 


800 


9- 


Labiatae 


33i 


4- 


Robiaceae 


611 


10. 


Urticaceae 


305 


5- 


Euphorbiaceae . 


624 


1 1. 


Asclepiadeae . 


249 


6. 


Acanthaceae 


5°3 


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 
1 7,000, 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 J. Hooker at 1600. 

There is apparently no other extensive region as varied 
in soil and climate as British India, in which Orchids occupy 
the first place in the sequence of the orders. This is due to 
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 tern- 



IV 



TROPICAL FLORAS 



45 



perate Andes, where Orchids are known to be extremely 
plentiful, the same proportion may exist ; but no such dis- 
trict appears to have been yet sufficiently explored by 
botanists. Before going farther 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) 

6. Cyperaceae (7) 

7. Rubiaceae (4) 

8. Compositae (9) 



1. Orchideae (1) 

2. Leguminosae (2) 

3. Gramineae (3) 

4. Urticaceae (8) 

5. Euphorbiaceae (5) 



9. Asclepiadeae 
10. Acanthaceae (6) 



The numbers enclosed in brackets give the sequence in 
Burma, which is very similar, except that Scitamineae (the 
Gingerworts) is the tenth order, while Asclepiadeae is 
excluded. 

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 comparison with others to be given farther on. 

Malay Peninsula (5138 species) 



I. 


Orchidaceae 




540 


7. Lauraceae 


153 


2 


Rubiaceae 




312 


8. Gramineae 


144 


3- 


Leguminosae 




266 


9. Zingiberaceae (Scitamineae) 1 37 


4- 


Euphorbiaceae 




255 


10. Gesneraceae 


131 


5- 


Anonaceae 




178 


1 1. Acanthaceae 


128 


6. 


Palmae . 


Ferns 


163 


1 2. Cyperaceae 
368 species. 


127 



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 Composite found in Sikhim 
and Burma ; while the Anonaceae (custard apples) ; the 
Lauraceae (true laurels), producing cinnamon, cassia, and 
many other spices and odoriferous nuts, barks, and fruits ; 
and, above all, the noble order of Palms, which have always 
been considered the most characteristic of the vegetable pro- 
ductions of the tropics, all take a higher place than in any 
part of India. Sir Joseph Hooker estimates the known 



46 THE WORLD OF LIFE chap. 

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 illus- 
tration of the increase in the number of species of Palms 
as we approach the equator, and renders them, with the 
Rubiaceae, the Euphorbiaceae, 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 him- 
self in the Malayan forests, which give an excellent idea 
of the general character of the vegetation, though unfor- 
tunately not many of the trees or other plants shown can be 
identified ; but a few remarks may be made as to their 
general character. 

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 orders ; and these form one of the most constant 
and characteristic features of the damp equatorial forests 
both in the eastern and western hemispheres. The slender 
shrub to the 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 vegetation 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 footing. The large twisted climber in the foreground 
is perhaps a Bauhinia (Leguminosae), though it may belong 
to any of a variety of genera, and even orders, which form 




Fig. i.— Forest in Kelantan, Malay Peninsula. 




s*«i# 



Fig. 2. — Forest in Perak, Malay Peninsula. 



IV 



TROPICAL FLORAS 47 



such ropes. The distinct ribbed leaf showing to the left of the 
most twisted part is probably one of the Melastomacese. The 
dwarf palms in the foreground are also very characteristic. 
Just above where the twisted climber goes out of sight is a 
climbing 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 them 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 white 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 
Nephrolepis 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 
photographs. 

Professor O. Beccari, in the interesting volume on his 
explorations in Borneo, tells us that when building a house 
on the Mattang mountain 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 
belong 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 pro- 
ductiveness 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 Philip- 



48 THE WORLD OF LIFE 

pines. It is probably at its maximum in Borneo, as 
Professor Beccari gives it as the twelfth in the sequence 
of orders as regards number of species: (l) Rubiaceae ; (2) 
Orchidaceae, 200 species ; (3) Euphorbiaceae ; (4) Legu- 
minosae ; (5) Anonaceae ; (6) Melastomaceae ; (7) Palmae, 
130 species ; (8) Urticaceae ; (9) Myrtaceae ; (10) Araceae ; 
(11) Guttiferae ; (12) Dipterocarpeae, 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 Burma 
and China, which has been at least as well explored by 
French botanists as have Burma and the Malay Peninsula 
by ourselves. Having been unable to obtain any statistical 
information on this area from English botanists, I applied 
to M. Gagnepain, of the botanical department of the Natural 
History Museum of Paris, who has kindly furnished me with 
the following facts. They have at the Museum very large 
collections of plants from all parts of this territory, collected 
from 1862 onwards, but great numbers of the species are 
still undescribed. Only small portions of the flora have 
been actually described in works still in process of publica- 
tion ; 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 New 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. This great land-area has the 
advantage 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 



IV 



TROPICAL FLORAS 49 



the Indian and Pacific Oceans. These conditions have led 
to its being almost wholly forest-clad, and to its possessing 
a flora comparable 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 wealth of species fully equal to 
that of the adjacent continent. 1 The remainder of the archi- 
pelago has had, however, a different origin, and has been 
much longer isolated. Celebes and the Philippines have 
certain 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 impoverished their mammalian fauna. New Guinea, 
however, stands alone, not only as the largest island in the 
world (excluding Australia), but as, in some respects, the 
most remarkable, 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 
that 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 

1 The Director of Kew Gardens informs me that, in 1859, the flora of the 
" Netherlands India," extending from Sumatra to New Guinea, but excluding 
the Philippines, was estimated by the Dutch botanists to possess 91 18 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. 

E 



50 THE WORLD OF LIFE chap. 

larger western 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 New Guinea, as to which we have 
recent information of considerable 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 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 Mr. Ridley's list, issued 
in 1908. The following is the sequence for the first twelve 
orders (excluding introduced plants) from Mr. Merrill's 
lists : — 

Philippines (4656 species) 



I. 


Orchideae 




372 


7. Cyperaceas 


137 


2. 


Rubiaceae 


. 


267 


8. Myrtacese 


105 


3- 


Leguminosae . 


. 


258 


9. Palmse . 


100 


4- 


Euphorbiaceae . 




227 


10. Asclepiadeae 


94 


5- 


Urticaceas, with Moraceae 


221 


1 1. Melastomaceee 


86 


6. 


Gramineae 




215 


12. Compositae . ' 


83 






Ferns 


• 


791 species. 





Comparing this with the Malay Peninsula (p. 45), we 
find the first four orders in similar places of the sequence, 
while Anonaceae, Scitamineae, and Melastomaceae give way to 
Myrtaceae, Palmae, and Asclepiadeae. 

The Philippine flora has a large proportion of its species 
peculiar to it. In some families, such as the Ericaceae, Ges- , 



! 



;IV 



TROPICAL FLORAS 51 



neracese, Pandanaceae, 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 
surrounding 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 Philippines and Celebes, y6 species having been found 
either identical or represented by allied species ; and, con- 
sidering how very imperfectly the Celebesian flora is known, 
the amount of similarity may be expected to be really very 
much greater. A similar 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 these 
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 
interesting island till 1898, when 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 peninsula (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 1 57 1 species, 
Df which nearly 700 were trees; and he has given lists of 
468 species which had been collected in various parts of the 
island by other botanists, making a total of 2039 species of 
lowering plants. The great peculiarity of the flora is 
ndicated by the fact that nineteen of the genera of trees 
are not known in Java ; while the affinities are, on the 
whole, more Asiatic than Australian, as is the case with the 
animals. The closest affinity is with the Philippines (as 
•vith the birds and mammals), indicated by two genera of 

r,;: crees {Wallaceodendron and Reinwardtiodendron), which are 
bund only in the two groups. Dr. Koorders also remarks 
:hat some of the plants have very peculiar forms, almost com- 
: Darable with those I have pointed out in its butterflies. One 

G: rf these is no doubt the new fig-tree (Ficus minahassd), 



52 



THE WORLD OF LIFE 



CHAP. 



a drawing of which forms the frontispiece of his 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 remark- 
able 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 the species in each natural order 
I will add a list of the ten largest orders for comparison with 
others here given : — 



1. Urticaceae. 


. 158 


6. 


Palmaceae 


78 


2. Leguminosae 


105 


7- 


Gramineae 


7i 


3. Rubiaceae . 


103 


8. 


Compositae 


63 


4. Euphorbiaceae . 


100 


9- 


Myrtaceae 


58 


5. Orchideae . 


81 


10. 


Meliaceaa 


58 



I will add a few words on a point of special interest to 
myself. Having found that the birds and mammals of the 
eastern half of the archipelago were almost wholly different 
from those in the western half, and that the change occurred 
abruptly on passing from Bali to Lombok, and from Borneo 
to Celebes (as explained in chapter xiv. of my Malay- 
Archipelago), the late Professor Huxley proposed that the 
straits between them should be called " Wallace's Line," as it i 
forms the boundary between the Oriental and Australian 
regions. But later, as stated in my Island Life, I came to the 
conclusion that Celebes was really an outlier of the Asiatic 
continent, but separated at a much earlier date, and that 
therefore Wallace's Line must be drawn east of Celebes and 
the Philippines. 

The Flora of New Guinea 

Early botanical explorers in New Guinea were disap- 
pointed by finding the flora to be rather poor and monotonous. 
This was the case with Prof. O. Beccari, who collected on' 
the north-west coast ; and Mr. H. O. Forbes, of the Liverpoo 
Museum, informs me that he formed the same opinion sc 
long as he had collected on the lowlands near the coast, bu 
that on reaching a height of near 1000 feet a much riche 
and quite novel flora was found. Prof. Beccari, who is a 
this time studying the palms from various recent Dutch 
British, and German collections, now thinks that the numbe 






IV 



TROPICAL FLORAS 53 



of species in New Guinea is probably as great, in equal 
areas, as in Borneo or the Malay Peninsula, but that the 
species are not so distinctly marked as in those countries. 
They are what he terms second-grade 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. 

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 New 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 

portions of the collections he has examined, will probably 

add another 1000 species. Again he says that from collec- 

:ions recently made by Schlechter in German New Guinea, 

and through letters from him, an " immense increase in the 

lumber of species is in prospect." A few more years of 

such energetic collecting will disclose more of the treasures 

}f this the largest of the great tropical islands, while its 

£rand central chain of mountains may be expected to 

oroduce a large amount of novelty and beauty. Dr. 

Lauterbach's conclusion, in a letter to Prof. Beccari, is as 

bllows : " I believe, indeed, that one would not estimate it 

foo highly if one reckoned the sum total of the Papuan 

Phanerogams at a round number of 10,000." Considering 

that New Guinea has more than double the area of the 

Philippines (which Mr. Merrill also estimates may contain 

to,ooo 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, 

ill between o° and n° of S. latitude ; that it has an ex- 

xemely varied outline ; that it possesses abundant diversity 

)f hill and valley, and a central range of mountains which 

lave now been proved to rise far above the line of perpetual 

now ; and finally, that it is almost everywhere clad with 

he most luxuriant forests, and enjoys that moist and equable 

:quatorial climate which is proved to be most favourable to 

7 egetable as well as to insect life, it seems to me probable 

hat it may ultimately prove to be among the richest areas 



54 THE WORLD OF LIFE 

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 portions of equatorial America. 

The only other tropical flora in the eastern hemisphere 
included 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 which 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 A merica 

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 will 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 unexplored, 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 peculiarities 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 the sequence of orders in Madagascar may be of 
interest for comparison with those of other large floras. 




IV 



TROPICAL FLORAS 55 

Madagascar (5000 species) 



I. 


Leguminosae 


. 


346 


5. Cyperaceae 


160 


2. 


Compositas 


. 


281 


6. Rubiaceas 


147 


3- 


Euphorbiaceae 


. 


228 


7. Acanthaceas 


131 


4. 


Orchideae 


Ferns 


170 


8. Gramineaa 
318 species. 


130 



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 given. 

Flora of Tropical America 

We have seen reason to believe that the temperate flora 
of North America is somewhat poorer than that of Europe 
and northern Asia, though the south temperate zone as re- 
presented by Chile 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 perhaps be indicated by the fact that it has 
fourteen or fifteen natural orders quite peculiar to it, while 
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 the eastern slopes of the Andes to beyond the 
southern tropic ; while all along the Atlantic coast there is 
a belt of equal luxuriance, spreading out again in the 
extreme south of Brazil and Paraguay to about 30° of south 



56 THE WORLD OF LIFE 

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 Paranahyba in northern Brazil, 
and then, after a break of a few hundred miles, along the 
east coast forests for about two thousand 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 species 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 flower. 
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 European oaks 
or beeches, birches or pines, produced bright-coloured 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 exceedingly 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 
botanists who alone could adequately cope with the work is 
comparatively so small, that it is not surprising to find that 
the great forest region of tropical America is still very 
imperfectly known. Only two considerable areas have been 
systematically collected and studied — in North America 



IV 



TROPICAL FLORAS 57 



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 monu- 
mental work, the Flora Brasiliensis of Martius, recently 
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 Central American flora, as described by Mr. Hemsley, 1 
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 numbers 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. Richard 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 proportion 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 the cataracts 
of the Orinoco to the mountains 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, Martius, myself, and others, there should still 
remain some 50,000 or even 80,000 species undiscovered. 

1 See Biologia Centrali Americana, by Messrs. Godman and Salveri ; Botany, 
4 vols., 1 888. 



58 THE WORLD OF LIFE 

To any one but me and yourself, this estimation will appear 
most extravagant, for even Martius (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." 1 

Spruce was one of the most careful and thoughtful of 
writers, and would never have made such a statement without 
full consideration 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 limited 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 dawn, 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 evident 
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 are found also in South America, and that about 
7CO are found in the eastern portion from Venezuela to 
Brazil, so that probably not more than 500 reach the 
latter country. The combined floras of Brazil and Central 
America, even as now imperfectly known, will therefore 
reach about 34,300 species. Now, 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 

1 See Spruce's Notes of a Botanist on the Amazon and Andes, vol. ii. p. 208. 



IV 



TROPICAL FLORAS 



59 



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 contains about half the great tropical forests of South 
America, and allowing that its portion is the best known, 
we may fairly add one-third of Spruce's lower estimate 
(25,000) to its present numbers, which will bring the whole 
to very nearly 40,000 species. 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), 1 more than half of which 
number will be absorbed by the comparatively well-known 
temperate floras, it will be apparent that we have at present 
a very inadequate idea of the riches of the tropical regions 
in vegetable 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 
tropical America, which, though very fragmentary, will serve 
to show the basis on which the preceding estimate of 
probable numbers rests. 

Floras of Tropical America 



Country. 


Area, 

Sq. Miles. 


Described 
Species. 


Remarks. 


Mexico (S). and| 
Central America ) 
Brazil 

Nicaragua to Panama . 
Jamaica 
Trinidad 
Galapagos . 


910,000 

3,200,000 

79,000 

4,200 

1,75° 
2,400 


12,000 

22,800 
3,000 
2,722 
1,967 

445 


Hemsley, 1888 

Martius 

Hemsley 

L. N. Brittan, 1909 

J. H. Hart, 1908 

(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 

1 This number has been given me by Mr. W. B. Hemsley, Keeper of the 
Kew Herbarium, as being that of Dr. Thonner in 1908. 



60 



THE WORLD OF LIFE 



CHAP. 



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 conditions with a similar flora also 
prevail over the great plateau of southern Mexico. This 
type of vegetation extends even farther south into the 
uplands of Guatemala, so that we only get a wholly tropical 
flora in the small southern section of the area from Nicaragua 
to Panama. 

The following table of the twelve largest orders in the 
whole flora will be of interest to compare with that of 
British India : — 



Mexico and Central America (ii,688 species) 



I. 


Compositae 




151S 


7. Euphorbiaceas 


2. 


Leguminosas 




944 


8. Labiataa 


3- 


Orchideas 




938 


9. Solanaceas 


4- 


Gramineas 


. 


520 


10. Cyperaceas 


5- 


Cactacese 


. 


500 


11. Piperaceae 


6. 


Rubiaceae 


Ferns 


385 


12. Malvaceae 
545 species. 



368 

250 

230 

218 

214 

182 



The most remarkable feature in this table is the great 
preponderance of Compositae characteristic of all the tem- 
perate and alpine floras of America, and the presence of 
Cactacese, Solanaceae, Piperaceae, and Malvaceae among the 
1 2 predominant orders, the first of the four being confined 
to America. 



TROPICAL FLORAS 61 

It may be noted that of the I 2 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 nearly identical, 
there may 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 which they abound. Thus 
the Urticaceae include not only nettles, hops, and allied 
plants, but mulberries, figs, and bread-fruit trees. Even 
with 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 Myrtaceae are found in hot or 
warm countries all over the world, the Eucalypti, so abundant 
in Australia, give to its vegetation a highly peculiar character. 
So the Onagraceae are found in all the temperate regions, 
yet the Fuchsias of South-temperate America are strikingly 
different from the Willow-herbs of Europe or the QEnotheras 
of North America ; and there are thousands of equally 
characteristic genera in all parts of the world. 

In Mr. Hemsley's elaborate table of the General Distri- 
bution 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 sub- 
divisions of the rest of the area. But the numbers added 



62 



THE WORLD OF LIFE 



CHAP. 



together will give more than the actual number of species in 
the combined flora, because an unknown 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 very 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 : — 

Nicaragua, Costa Rica, and Panama (3000 species) 

1. Orchideae . 

2. Compositae 

3. Leguminosae 

4. Rubiacese . 

5. Gramineae 

6. Euphorbiaceae 
Ferns 

This table brings out clearly the extra-tropical character 
of Mexico as compared with these tropical sections of Central 
America. No less than five orders of the former twelve have 
to be omitted (Cactaceae, Labiatae, Solanaceae, Piperaceae, 
and Malvaceae), which are replaced by the more exclusively 
tropical Gesneraceae, Melastomaceae, Urticaceae, Aroideae, and 
Palmae. Here, in two adjacent areas differing about 12° in 
mean latitude, there is a more pronounced difference in the 
prevalent orders of plants than exists between two great 
regions on opposite sides of the globe. Another character- 
istic 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. 





286 




197 




176 1 




146 




90 




72 



7. Gesneraceae 


69 


8. Cyperaceae 


68 


9. Melastomaceae 


67 


10. Urticaceae 


58 


1 1. Aroideae . 


54 


12. Palmae 


5o 


252 species. 





,v TROPICAL FLORAS 63 

Jamaica and Trinidad are the only West Indian islands of 
the larger group for which I have been able to get recent 
figures. Mr. L. N. Brittan, of the New York Botanical 
Gardens, 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 growth of plants 
at or near the sea-level, as has been pointed out in my 
Island 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 by a Danish 
botanist, Professor Eug. Warming, who lived there for three 
years with his fellow-countryman Dr. Lund, who first studied 
the fossil vertebrates in the caves of the district. This was in 
1863-66 ; 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 char- 
acteristic illustrations, both of individual plants and of 
scenery, forming one of the most interesting botanical works 
I have met with. Unfortunately 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 moisture and a rich forest vegetation. But 



64 



THE WORLD OF LIFE 



CHAP. 



everywhere else is for half the year arid and sun-baked, 
covered with scattered deciduous trees and shrubs, and 



,..;■, 






Jllfll 



Li , 

VI 



Ml 






i fi 



C X 



, 



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i 
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1 1 1 






Will 




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o 

a 

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O 

C/! 

o 

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a 
X 

b 
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during the rains producing a fairly rich herbaceous vegeta- 
tion. 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 



IV 



TROPICAL FLORAS 65 



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 country is so open, with trees and shrubs spread 
over it in a park-like manner, Mr. Warming tells us that 
trees of the same species 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 — 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. 

Through the kindness of Professor Warming I am able 
to reproduce here a few of his characteristic drawings and 
photographs, with descriptions furnished by himself. These 
Dffer a striking contrast to the photographs of typical 
Malayan vegetation at pp. 46 and 47. 

As shown in the view opposite (Fig. 3) the vegetation 
covering the hills is what is termed " campos limpos," 
:onsisting of grasses and herbs with small shrubs, but 
mth few trees scattered in the grass-land. These trees are 
ow, the stems and branches tortuous or twisted. In 
:he valleys where the soil is richer in humus and always 
noist, there is thick forest. The soil in all the campos is red 
:lay. In the distance is seen the smoke of fires on the 
:ampos. In the foreground is a " campo cerrado," i.e. a 
:ampo with many trees, but never so close that the sun does 
lot shine on the dense carpet of high grasses and herbs under 
:he trees ; which latter belong mostly to the Leguminosae, 
Ternstromiaceae, Vochysiaceae, Anonaceae, Bignoniaceae, etc. 

Fig. 4 (overleaf) shows the stunted form of the trees 
.vhich characterise the " Campo cerrado." In the back- 
ground are calcareous cliffs, in which are the fossil- 
Droducing caves. At the foot of the cliffs the trees are 
:loser and higher ; and on the top is a more open and 
iry forest, each kind of forest having its peculiar species of 
:rees. 

Fig. 5 (facing p. 66) is a view taken close to the rocks. 
The upper branches of Mimosas and other trees are shown, 
■vhich grow at the foot of the cliffs, one of them being a 
:ree of the custard-apple family, whose branches are fruit- 

F 



66 



THE WORLD OF LIFE 



CHAP. 



laden. Numerous tall cactuses {Cereus cczrulescens) 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, 




Fig. 4. — The Campo Cerrado ; Lapa Vermelha Rocks to the Right. 

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 
numerical data of interest to botanical readers. The sequence, 
of the orders in this very interesting flora is as follows ::— -» 




o 

< 

X 

Hi 

OS 
> 






«5 
O 



o 
w 



< 

a 
p 

o 

X 



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IV 



TROPICAL FLORAS 



67 



Lagoa Santa (2490 species) 



I. 


Composite 


266 


7- 


Rubiaceae 


94 


2. 


Leguminosas . 


235 


8. 


Cyperaceas 


77 


3- 


Graminese 


15S 


9- 


Malpighiaceae . 


64 


4- 


Orchidaceae 


120 


10. 


Melastomaceae 


62 


5- 


Euphorbiaceae . 


106 


1 1. 


Labiatae . 


+9 


6. 


Myrtaceae 


106 


12. 


Asclepiadeae 


48 




Ferns and allies 




106 species. 





The chief feature which distinguishes this flora from that 
of Nicaragua and Costa Rica is the presence in some abund- 
ance of the highly characteristic South American order 
Malpighiaceae, the high position of Myrtaceae, with Labiates 
and Asclepiads 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 Drought 

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. 69 
(Fig. 7), which is adapted to the same conditions in a 
quite different way, as are many other quite unrelated 
species. 1 The group of plants shown is really an under- 
ground tree, and not merely dwarf shrubs as they at 
first appear to be. What look like surface - roots are 
the upper 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, 

1 The following species have a similar mode of growth : Anacardium humile, 
Hortia Brasiliensis (Rutaceoe), Cocklospermum insigne (Cistacese), Simaba 
Warmingiana (Simarubacese), Erythroxy'on campestre (Erythroxylacere), Plumicra 
Warmingii (Apocynacese), Palicourea rigida (Cinchonaceas), etc. 



CHAP. 



68 THE WORLD OF LIFE 

which are 4-5 inches diameter, while the growing shoots 







Fig. 6. — Casselia Chamaidrifoua, nat. size (Verbenacese). 

are from 2 to 3 feet high. The whole plant (or tree) is 
from 30 to 40 feet diameter. As the branches approach 



IV 



TROPICAL FLORAS 



69 



the centre they descend into the earth and form a central 
trunk. A French botanist, M. Emm. Liais, says of this 
species : " If we dig we find how 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. Renault 
of Barbacena told me that he had dug about 20 feet deep to 
obtain one of these trunks." The large subterranean trees 




Fig. 7. — Andira Laurifolia (Papilionacese). 

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, supple- 
mented by some details in a letter. They are certainly very 
remarkable ; 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 



70 THE WORLD OF LIFE 

fires pass 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 where there has been no fire, and often 
produce flowers when unburnt trees or shrubs of the same 
species remain flowerless. Mr. Warming and other 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 Martius, Burchell, and Gardner, cannot be compared with 
those furnished by the Cape. The number of endemic species 
may perhaps 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 words : " The country is beautiful, and 
richer than any 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 temperate with tropical floras, 
there can be no doubt as to the superiority of the latter. 
This point will, I think, be made still clearer in the following 
discussion of some almost unnoticed facts. In the case of 
Brazil and Cape Colony, however, it is clear that Griesbach 
was greatly in error. The whole 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 we find less than 14,000 species in the 
former against 22,800 in the latter. It will be now shown 
that when smaller and better known areas are compared the 
superiority of the tropics is more clearly apparent. 



IV 



TROPICAL FLORAS 



71 



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 
confirmation, 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-popu- 
lation 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 
temperate zones, each arranged in the order of their area in 
square miles for reference and comparison. 

Tropical Floras — Small Areas 





Place. 


Area. 

66o 

206 

107 

66 

i* 

1* 


Species. 


Authority. 


I 

2 

3 

4 

5 
6 


Malacca 

Singapore 

Penang 

Lagoa Santa, Brazil 

Mount Pangerango, Java 

Kambangan Island, Java 


2000 
1740 
1813 
2488 
1750 
2400 


Gamble 

Ridley 

Curtis 

Warming 

Koorders 

Koorders 





Temperate Floras 


— Small Areas 


1 

2 

3 


Place. 


Area. 

360 
180 
114 


Species. 


Authority. 


Mount Nikko, Japan 
Cape Peninsula 
Schaffhausen 


800 

1750 
1020 


Hayati 

Bolus 

A. de Candolle 


4 
5 


Washington, D.C. 
Hertford (near) 


108 
80 


922 
810 


Ward 

A. de Candolle 


6 

7 
8 

9 
10 


Paramatta River, Sydney 
Capri, Italy . 
Edmondsham, Dorset . 
Cadney. Lines 
Thames Ditton 


20 
4 
3 
3 
1 


620 
719 

640 
720 
400 


H. Deane 

Beguinot 

Rev. E. F. Linton 

Rev. Woodruffe-Peacock 

H. C. Watson 



72 THE WORLD OF LIFE 

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, poured 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 
wonderful silver-tree, the splendid lilies and curious orchises, 
the endless variety of leguminous shrubs, and the composites 
including the everlasting flowers, 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 species, 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 1 8 1 3 species. Sir Joseph D. Hooker, in his Sketch 
of the Flora of British India (1906), terms this " an astonish- 
ing number of species," and remarks on the large proportion 
which are arboreous, and of the altitude of the island being 
only 2750 feet. Here, therefore, in an area considerably less 
than that of the Cape Peninsula, the species are actually 
more numerous, and this was evidently a new and astonish- 
ing 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 elevation being only a few hundred feet. A large 
part of the surface is occupied by the town and suburbs, 
while the original forest that covered it has been almost all 



IV 



TROPICAL FLORAS 73 



destroyed. Yet Mr. Ridley finds it to have recently con- 
tained 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 against 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. When I was in Java about fifty 
years ago I ascended the celebrated mountains Ged^ and 
Pangerango, the former an active, and the latter, much the 
higher, an extinct volcano. The two, however, form one 
mountain with two summits. During the ascent I was much 
impressed by the extreme luxuriance 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 



74 THE WORLD OF LIFE chap. 

Java with a much larger number of phanerogams, e.g. the small 
island of Noesa 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 o - 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 instead of 3 square kilometres. So I wrote to 
him again asking 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." 1 It thus became 
clear that no mistake had been made. I was further satisfied 
of this by referring to a small volume by M. Jean Massart, 
entitled Un Botaniste en Malaisie. He there describes the 
" mountain reserve " 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-flora " 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 

1 It may seem to some readers, as it did at first to myself, that it is impossible 
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 176 = 30,976 trees. But in 
Kambangan Island there are 600 species of trees in 1^ 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. 




< 

H 

£ 6: 



— 

J 



Wj £1 



PS 

o 



IV 



TROPICAL FLORAS 75 



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 southern 
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. 46 and 47). 

The system of small forest reserves in tropical or other 
imperfectly known countries seems to me to offer so many 
advantages 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 effective ; 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 exten- 
sive country or island, a suitable number of what may be 
termed " botanical reserves " (but which will also serve as 
zoological reserves, 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. Experience 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 super- 



76 THE WORLD OF LIFE chap. 

intendent or keeper would have time and opportunity for the 
collection 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 
easily found as in a mile of unbroken forest, and would not 
be much more numerous. In any new tropical country of 
which we 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 
determination of the plants growing on a definite if small 
area over that which has usually been adopted of, as it were, 
skimming 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 there- 
fore 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 accuracy. 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 Kambangar 
Island they form one-fourth. If there are, as Dr. Koorders 
tells me, about 1200 species of trees actually found in Java 



I 



TROPICAL FLORAS 77 

ind if, on account of the eastern part of the island having 
nuch less lowland forest, we take one-fifth as the more prob- 
Lble proportion for the whole, then the flora of Java may 
)e estimated at a minimum of 6000 species ; and if the 
lumber of the trees is found to be greater, then at a propor- 
ionately higher number. Hence it is very important that 
n each local flora the number of its trees, shrubs, and herbs 
hould be separately given. It appears that a forest reserve 
if 17 square miles has been established on the Bay of 
Manilla ; but, as it is as yet very imperfectly explored, it 
irould be more useful to thoroughly explore two or three 
/ell-chosen areas of one square mile each. 

It is really deplorable that in so many of our tropical 
lependencies no attempt has been made to preserve for 
losterity any adequate portions of the native vegetation, 
specially of the virgin forests. As an example, the island 
/{ Singapore was wholly covered with grand virgin forest at 
he beginning of last century. When I was there in 1854 
he greater part of it was still forest, but timber-cutting and 
learing for gambir and other plantations has gone on with- 
ut restriction till there is now hardly any true virgin forest 
ift ; and quite recently the finest portion left has been 
llowed to be destroyed by a contractor in order to get 
ranite for harbour works, which might almost as easily have 
een obtained elsewhere. The grand forest trees were 
ctually burnt to make way for the granite diggers ! 

Surely, before it is too late, our Minister for the Colonies 

hould be urged without delay to give stringent orders that 

,i all the protected Malay States, in British Guiana, Trinidad, 

amaica, Ceylon, Burma, etc., a suitable provision shall be 

lade of forest or mountain " reserves," not for the purpose 

f forestry and timber-cutting only, but in order to preserve 

dequate and even abundant examples of those most glorious 

nd entrancing features of our earth, its native forests, woods, 

lountain slopes, and alpine pastures in every country under 

, ur control. It is not only our duty to posterity that such 

sserves should be made for the purpose of enjoyment and 

tudy by future generations, but it is absolutely necessary in 

rder to prevent further deterioration of the climate and 

estruction of the fertility of the soil, which has already 



78 THE WORLD OF LIFE chap. 

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 continuous belts of at least 400 or 500 
yards wide should be reserved wherever forests still exist, 
or where they have been already lost be reproduced as soon 
as possible, so as to form 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 adequate extent to give a represen- 
tation of each type of vegetation 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 property 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 exception to the rule that all river 
and streams except the very smallest should be reserved a 
public property and absolutely secured against pollution 
while all natural features of especial interest or beauty 
should also be maintained for public use and enjoyment. 

The great Roraima mountain in British Guiana, foi 
example, with at least half a mile of forest around its base 
should, so far as we are possessors of it, be absolutelj 
secured ; and generally, every important mountain summit 
with ample means of access, should also be reserved, so tha 
they may not be monopolised or defaced by the greed 
speculative purchasers. It should always be kept in mine 






iv TROPICAL FLORAS 79 

that the reckless clearing of large forest-areas, especially in 
the tropics, produces devastation which can never be re- 
paired. It leads to the denudation of the rich surface soil 
by 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 N. Celebes, and in four months, 
between the sea-level and 6500 feet, he collected or observed 
about 2000 species of flowering plants, of which 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 successive years, not a single species 
could have escaped discovery. This would imply that the 
forest flora of North 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 would 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 properly distributed over the islands from Sumatra to 
New 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 exploration would be the 
result than the labours of all other collectors 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 



80 THE WORLD OF LIFE 

and publish the results of their combined work on a uniform 
plan, and in a cheap form, the total expense 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 discovery of great numbers 
of plants of utility or beauty, and would besides form a 
basis of knowledge from which it would be possible to 
approach the various great governments urging the establish- 
ment, 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 evidence 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 Europe. The table of extra-European small 
areas (p. 36) shows that the great Japanese mountain, Fuji- 
yama, with a larger area and an altitude of over 12,000 feet, 
has a smaller number of species than Mt. Nikko, 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 fully explored by the same botanist, one on a grand 
mountain slope from 4500 to 9500 feet, and celebrated for 
its rich flora, the other at the sea-level, and the latter is 
decidedly the richest. Yet we find Gardner, in his Travels 
in Brazil, taking the very opposite of this for granted. He 
says, at the end of his work : " No 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 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 



IV 



TROPICAL FLORAS 81 



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 Cadney, 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 
(probably on the chalk downs of Kent or the Isle of Wight), 
he found twenty species of plants belonging to eighteen 
genera (Origin of Species, 6th ed. p. 88). Sir Joseph 
Hooker in the Himalayas, 1 1,480 feet above the sea, in the 
upper Lachen valley, found a much richer vegetation. He 
says : " Herbaceous 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 he adds : "In England thirty is 
on the average the equivalent number of plants which in 
favourable localities I have gathered in an equal area." 1 

In my limited reading I have found no other reference 
; to this form of species-abundance, nor do any of my 
botanical friends appear to have recorded such ; but it 
would be interesting to know if any parts of Switzerland or 
the Pyrenees are 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, 

1 Himalayan Journals (cheap ed.), p. 335. 

G 



82 



THE WORLD OF LIFE 



CHAP. IV 



while the more nearly vertical sun and much greater rain- 
fall would probably lead to a more luxuriant development 
of species than in higher latitudes, or less elevated stations. 
Darwin points out that the production 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 delightful 
expanses 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. 



CHAPTER V 

THE DISTRIBUTION OF ANIMALS 

The sketch now given of the broader features of the 
distribution of plants over the various parts of the earth's 
surface will apply, with little modification, to the various 
classes of animal 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 
instructive 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 Field 

Club. 

Distribution of Lepidoptera 

Area, 

Sq. Miles. S P ecies - 

Great Britain .... 87,500 2070 

Essex . . . . . 1 .,5 30 1655 

In order to compare the numbers in a smaller area, I 
have only materials for the Macrolepidoptera or Butterflies 
and larger Moths. 

Area, 

Sq. Miles. S P eC1CS - 

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 the same as the area in miles ; 

83 



84 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 (ioio) 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 larvae feed 
on several distinct plants indiscriminately. 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 least 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 Macro- 
lepidoptera found in the county. Here, too, we see the 
result of the dependence of the insects on the plants, the 
great variety of the latter in Epping Forest (450 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 
cultivated. 

Area. Species. 

Great Britain .... 87,500 3260 

Essex ..... 1,530 I0 55 

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. 

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 



DISTRIBUTION OF ANIMALS 85 

of the Entomological Department of the Natural History 
Museum. 



Insects of the World. 

Coleoptera (Beetles) .... 
Lepidoptera (Moths and Butterflies) 
Hymenoptera (Bees, Wasps, Ants, etc.) 
Diptera (Flies, Gnats, Midges, etc.) 
Rhynchota (Bugs, Cicadas, etc.) . 
Orthoptera (Locusts, Crickets, etc.) 
Neuroptera (Dragon-flies, May-flies, etc.) 
Several smaller Orders 



Number of Described 
Species. 

120,000 

60,000 

45,000 

28,000 

18,000 

8,000 

5,000 

5,000 



Land Area, 48,000,000 square miles . . . 240,000 

If we consider that large areas of the most productive 
tropical regions are still almost unexplored by the entomo- 
logist, 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 
estimate 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 Museum. His estimate then was 220,150 species of 
insects. In the twenty-seven succeeding years, the Zoo- 
logical 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 year by year, and 
Mr. Shipley has therefore taken the number for the year 
1897 as an average of the whole (8364 n.s.), and multiply- 
ing this by 27 (allowing the odd 364 for synonyms) we 
have an addition of 216,000, which added to 220,000 gives 
; a total now known of 436,000, 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 



86 THE WORLD OF LIFE 

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 Curculionidae, or Weevils — I obtained also about 
1000 species, of which the same proportion were new. While 
the former group are remarkable for grace of form, variety 
of marking, and often for exquisite coloration, the latter 
are equally interesting for their endless modifications of 
shape, more sober but beautifully marked bodies, strangely 
bossed surfaces, and, occasionally, 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 coloration have been due to general laws in 
operation for countless 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 exhibited them. 
This, however, will be shown later on, when we have to deal 
with the more important factors of evolution — variation 
and heredity. 

The Species of Birds 

We will now pass on to the most familiar, the most 
beautiful, and the most wonderful of all living things — the 
birds. These form one of the culminating lines of develop- 
ment of the great world of life ; they are the most 
specialised of all the higher animals ; and so far as perfec- 
tion of organised structure is concerned may be considered 
to hold a higher place than the mammals themselves. 



DISTRIBUTION OF ANIMALS 87 

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, some- 
times 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 perfect 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 
surface as compared with the other forms of life already 
considered, 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 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 us 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 considered to be truly 
natives, in our case to be " British birds." But others only 
visit us occasionally, some at very long intervals, while others, 
again, are mere " stragglers," who have lost their way or been 



88 



THE WORLD OF LIFE 



CHAP. 



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 regions. 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. Gunther, in 1881, estimated the species of birds 
then known at 1 1 ,000, and Mr. Shipley added to this an 
average of 105 new species per annum — estimated from the 
Zoological Record — for the twenty-seven years elapsed since 
that date, bringing the total up to 13,835. But in the late 
Dr. Bowdler Sharpe's Hand List of the Genera and Species 
of Birds, just completed, the number is stated as being 
1 8,937. This enormous divergence, as I am informed by 
another great authority on Ornithology, Dr. P. L. Sclater, is 
mainly, if not wholly, due to the fact, that Dr. Sharpe 
" includes 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 
differences to require separation at all." 

Keeping these difficulties in 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 



Areas. 


Square Miles. 


Number of Species. 


Europe 
Great Britain 
Dorset 


3,850,000 

87,000 

988 


770 
410 
2I0 1 



1 Mansel Pleydell's Birds of Dorset. 



DISTRIBUTION OF ANIMALS 89 



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 with flowering plants and 
some of the most extensive orders of insects. 

The difficulty of obtaining really comparable figures for 
the following countries and regions is at present insuperable, 
but the approximations given are of considerable interest. 

Table of the Species of Birds 





Area, 


Number of 




Region or Country. 


Sq. Miles. 


Species. 


Authorities. 


Palsearctic Region . 


17,000,000 


1250 


Dresser 


Nearctic Region 


8,000,000 


760 


Ridgway 


Ethiopian Region . 


7,555,000 


2490 


Reichenow 


Oriental Region 


3,350,000 


2300 


Estimate 


British India 


1,560,000 


1 6 1 7 


Dresser 


Borneo 


297,000 


500 




Philippines . 


115,500 


700 


Ernst Hartert (1910) 


Neotropical Region 


7,590,000 


4100 




Central America and 


940,000 


1300 ? 


Biol.Am.Cent.(i9o5) 


South Mexico 








Brazil . 


3,288,000 


1568 


Von Thering (1907) 


Australian Region . 


3,500,000 






Australia 


3,009,000 


883 


E. Hartert (1908) 


New Guinea . 

1 


310,000 


950 


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. 



The preceding table exhibits several points of interest, 
especially as regards the correspondence of the proportionate 
numbers of such different organisms as birds and plants. 
As regards the Palsearctic and Nearctic regions (temperate 
Europe and Asia on the one hand, temperate North 
America on the other), we see that the birds of the former 
are about one and a half times those of the latter, the areas 



90 THE WORLD OF LIFE 

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 io,ooo, 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 be about equal to additional species 
of the whole of North Asia and Japan, we get a total of 
3 1 ,000 species, which is far beyond the highest estimate of 
the Nearctic 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 Region is much more difficult to 
arrive at. Taking 15,000 species for the tropical portion of 
the flora of British India, and adding 7000 for Indo-China, 
5000 for the Philippines, 4000 for Java, and the same for 
additional species of Malaysia proper (Malay Peninsula, 
Borneo, and Sumatra), and 2000 for Celebes, we have a 
total of 30,000, which, considering that the land area of 
this region is less than half that of the Ethiopian, shows 
what is probably 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 Neotropical Region (including all 
South America and tropical North 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« 59) I have arrived at 80,000 species as a not improbable 
number of the flowering plants for the Neotropical 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 proportionate numbers of birds in the 
same regions. 

The Australian Region is of less importance from the 



DISTRIBUTION OF ANIMALS 91 

point of view we are now considering, because it is not 
exclusively temperate or tropical, but nearly equally divided 
between the two. It also differs from the Oriental inasmuch 
as botanists usually claim the flora of the Moluccas and 
New Guinea as being essentially Malayan, and therefore 
belonging to the Oriental Region. But the flora of New 
Guinea has been stated by Sir Joseph Hooker to be so 
peculiar as almost to deserve to form a Sub-region of its 
own ; and, till recently, the natural order Dipteraceae, con- 
sisting 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 New Guinea ; but as westerly winds blow for half the 
year with great steadiness between Celebes and New Guinea, 
it is not difficult to explain their presence in the latter country, 
as their solid but large-winged fruits would be easily drifted 
for long distances. At all events the extreme richness of 
New Guinea in both birds and plants, and not improbably in 
insects also, is a matter of very great interest. 1 

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 
birds 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. 

1 For a full explanation of the six great Zoological Regions, here enumerated, 
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. iii. 



92 



THE WORLD OF LIFE 



CHAP. V 



Lydekker that he considers the Mammalia to be much 
exaggerated 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 
enormous, Mr. D. Sharp, a very experienced entomologist, 
thinks that the number actually existing is five times as 



great- 



-that is, more than two million distinct species 



An Estimate of the Described Species of Living Animals. 
By A. E. Shipley, F.R.S. (B. Assn. Address, 1909) 



Class. 


Estimated by 
Gunther, 1881. 


A. E. Shipley, 
1909. 


Remarks. 


Mammalia. 


2,300 


9,955 


Too high ! 
(R. Lydekker) 


Birds 


I 1,000 


13,835 


18,939 
(R. B. Sharpe) 


Reptiles, Batrachia 


3,400 


7,180 




Fishes 


I 1,000 


14,996 




Mollusca . 


33,000 


62,000 




Bryozoa 


I20 


222 




Crustacea . 


7,500 


13,953 




Spiders, etc. 


8,070 


25,870 




Myriapods 


1,300 


8,725 




Insects 


220,150 


445,978 


Too low ! 
(D. Sharp) 


Echinoderms 


1,840 


15,097 




Worms 


6,070 


8,716 




Ccelenterata 


2,200 


5,008 




Sponges . 


400 


2,965 




Protozoa . 


3,300 


6,000 




790,533 



; 



CHAPTER VI 

THE NUMERICAL DISTRIBUTION 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 definite 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 
technical terms, and is therefore especially suitable for a 

93 



94 THE WORLD OF LIFE 

work such as the present. We will now proceed to a 
brief consideration 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 II.), 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 the number of the species it contains, or in 
the species themselves, 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 exposure 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 Darwin 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 v/riter 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 he is able 
in many cases to define the causes of that individuality. 
Besides the ordinary 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. 



v, DISTRIBUTION AND EVOLUTION 95 

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 
development 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 competition 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 
Caryophyllaceae, Primulacese, and a Geranium are also shrubs 
or small trees. In the Azores a Campanula and a Semper- 
vivum are shrubs. 

Again, the knowledge we have recently gained of the 
wonderfully rich mammalian fauna of temperate North 
America in middle and late Tertiary times — camels, 
ancestral horses and cattle, mastodons, and many others, 
which disappeared at the on-coming of the glacial epoch — 
affords us a very important 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 North and South America in late 
Tertiary 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 vegeta- 
tion, as well as of the animal life, in the respective areas. 

No less indicative of delicate response to variation of 
temperature, and therefore of close adaptation to the whole 
modified 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, 



96 THE WORLD OF LIFE 

and is therefore liable to be masked by other favourable 
or adverse conditions 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 pro- 
nounced 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 
temperate 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 necessarily 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 im- 
portance to vegetation so long as other conditions remain 
tolerably uniform and favourable. 

It is this long-continued uniformity of favourable con- 
ditions within the tropics, or more properly within the great 
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 monopolise large areas 
to the exclusion of others. Hence also it has come about 
that the equatorial species seem to be better defined — more 
sharply distinguished from each other — than many of those 
of the temperate 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 continental mass. It is interest- 
ing to note that Mr. Th. D. A. Cockerell has arrived at a 
similar conclusion from his study of the rich fossil flora of 






VI 



DISTRIBUTION AND EVOLUTION 97 






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 extinction is 
traceable to the great changes, inorganic and organic, that 
have since occurred in North 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 N. America, 
there has been room for expansion, and hence the very numerous 
and closely allied species of Aster, Solidago, Senecio, and other 
plants, as well as allied species of butterflies of the genera Argynnis, 
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. 
Below 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 afterwards 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 quintuple it. But in all such comparisons we require a 
large number of fairly comparable cases to give a trust- 
worthy 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 ioo square miles, or much larger 
areas of from 100,000 to 200,000 square miles, there is, 

H 






98 THE WORLD OF LIFE 

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 warmer 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. Towards 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. Farther 
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 great variety of trees, though never so completely inter- 
mingled 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 the warmest and 
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 
adaptations by which every well-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 









vi DISTRIBUTION AND EVOLUTION 99 

or the small quantity 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 great 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 supporting 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 another. 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 appears 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 
plants, especially mosses and hepaticse, that cover the whole 
>urfaces of the leaves of forest trees with an exquisite tracery, 
:hus 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 
itream miles of alluvial plains are regularly under water for 
several months, both trees and shrubs have become adapted to 
hese strange conditions, and the greater part, if not all, 
he species are quite distinct from those which grow on the 
tnflooded land. 

All these, and many other characteristic features of 
ropical vegetation, can be explained by the general 
onstancy of the inorganic conditions, especially the climatic 
nes, which have undoubtedly prevailed there during whole 
eological periods, subject only to those very slow changes 
ue to elevation, depression, and denudation of the land 
self. These latter have been so extremely gradual as to 
:t as a gentle stimulus to the various agencies continually 



100 THE WORLD OF LIFE chap, vi 

bringing about modification of specific forms ; 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 constant 
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 
temperate or cold regions. Whether we consider the differ- 
ences between day and night temperatures, the variations of 
temperature from month to month or from year to year, or 
those extreme variations which we experience once perhaps 
in a generation or in a century, such as excessively cold 
winters, excessive droughts or excessive rains in summer, or 
long periods of dry and cold winds — all alike are unknown 
in the equatorial 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 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 occur in single fields long subject to almost identical 
conditions in our own country, with the additional fact that 
no plot of a few 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 wonderful balance and adaptation of each to 
all. How this result has been actually brought about in the 
course of evolution through the ages we shall better under- 
stand after a brief exposition of the factors which have 
been the immediate causes of the two great phenomena, 
continuous evolution, with continuous adaptation. 



* 

; 



CHAPTER VII 

HEREDITY, VARIATION, INCREASE 

IN the preceding chapters I have shown how, from a 
consideration of the simple facts of the numerical distribu- 
tion 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 struggle 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 metJiod 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, 1868, but which 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 interest even by the evolutionist of to-day. 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 effect had 
been hitherto unperceived and neglected. The two first of 
these factors we will now proceed to discuss and elucidate. 

Perhaps the most universal fact — sometimes termed 

101 



102 THE WORLD OF LIFE 

" law " — of the organic world is, that like produces like — 
that offspring are like their parents. This is so common, so 
well known to everybody, so absolutely universal in ordinary 
experience, 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 produce 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 producing 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 
inherited, because it so often happens that men of genius 
have quite undistinguished parents, and that the children of 
men of great ability do not as a rule equal their fathers. 
But although such cases are frequent and attract attention 
because such apparent non-inheritance is unexpected and 
seems unreasonable, 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 generally 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 briefly 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 inheritance under normal conditions. It is that 



HEREDITY, VARIATION 103 

the offspring of any two parents derive, on the average, 
one-half of their characteristics from those parents, one- 
fourth from their four grandparents, 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 
well-known fact that certain peculiarities of body or of 
character are apt to reappear in families during several 
centuries. 

Now this simple law explains almost all the facts includ- 
ing the apparent failures of inheritance — all its irregularities 
in individual cases, together with its constancy and regularity 
when large numbers are examined. It shows us why, when 
families for several generations have been noted for beauty, 
for stature, for strength, or for talent, these characters will 
almost certainly be found developed in most of their 
children, who from three or four generations of ancestors 
have a good chance of deriving seven-eighths or fifteen- 
sixteenths of their entire organisations. If, on the other 
hand, the beauty or talent of parents were exceptional in 
their respective families, then tlieir children, having a number 
of commonplace or inferior ancestors, would 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. 

From this consideration there is deduced another general 
law, very easy to remember and of great use in explaining 
apparent deviations or incongruities. This is called the 
" law of recession towards mediocrity." It means that, 
whenever parents deviate considerably from the average of 
the population of which they form a part, their offspring 
will tend to return towards the average. For example, 
if both parents are decidedly below or above the average in 
height, in beauty of form, in any special faculty, as music, 
drawing, etc., their children will usually go back toivards 
the average, though still retaining some of the parental 
excess or defect. It is owing to this law that very extreme 
developments, whether of body or of mind — gigantic stature 
or supreme genius — are rarely transmitted to the next 



104 THE WORLD OF LIFE chap. 

generation. But if this special superiority has already 
persisted in the family for several generations, 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 plants 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, rejecting 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 towards mediocrity " appear to be abolished. 
But it is not really abolished. The average to which 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 ioo to I against the inferior char- 
acters 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 we 
shall see farther on, that Nature works to improve her 
stocks in the great world of life ; and has been thus enabled 
not 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 



VII 



HEREDITY, VARIATION 105 



the privilege and delight of the naturalist to seek out, to 
study, and to marvel 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, commonly 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, which is yet so frequently 
misapprehended, 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 variation 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 distinctness of species, 
which they considered to be a fundamental and certain fact 
of nature. Hence, perhaps, it was that Darwin 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 compared. 
He therefore always guarded himself against assuming its 
presence whenever required by using such expressions in 
regard to the power of natural selection as, " If they vary, for 
unless they 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 



106 THE WORLD OF LIFE 

variation so large and so universal as to fully satisfy all the 
needs of the evolutionist for bringing about whatever 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 women. 
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 whole 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 whole 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, intelligent or 
stupid, poetical or prosy, witty or obtuse. And all these 
characteristics, whether physical or mental, are combined 
together in an infinite variety of ways, as if each of them 
varied independently with no constant or even usual 
association with any of the others ; whence arises that 
wonderful diversity of appearance, attitudes, expression, 
ability, intellect, emotion, and what we term as a whole 
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 



HEREDITY, VARIATION 107 

manifested in Socrates and Plato, Homer and Virgil, 
Alexander and Phidias, Buddha and Confucius in the older 
world ; in Shakespeare and Newton, Michael Angelo, Fara- 
day, 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 
variation is minute, is even infinitesimal, and only occurs at 
long intervals in single individuals, and that it is quite in- 
sufficient 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 develop- 
ment 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 carefully examined and measured, and 
it is to some of these that we 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. Before giving examples of the variation of 
the higher animals it will be advisable to show what is 
meant by 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 importance 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 hundreds or 



108 



THE WORLD OF LIFE 



CHAP. 



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 
showing 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 error," but for our 
purpose may be termed the curve of frequency. 

The diagram here given represents this curve obtained 




Dwarfs Average Men Ciants. 

CURVE OF STATURE. (BRITISH). 

Fig. 9. — Diagram of Height of 2600 Men. 

by 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 succes- 
sive heights. The central line through the highest point of 
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. 



HEREDITY, VARIATION 109 

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 extremes 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 measurements of a few thousand among- 
a fairly mixed population will give us the mean height of 
the whole, very nearly ; 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. 

The diagram here given is formed from the measure- 
ments of six separate portions of twenty male specimens of 
the Bob -o'- link or Rice -bird {Dolichonyx otyzivorus), very 
common in North America. All were obtained in the same 
place on the same day, so that there could be no suspicion 
of their being in any way selected as especially variable. 
It is a little larger than our yellow-hammer, and is there- 
fore 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 twenty 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,. 



110 



THE WORLD OF LIFE 



CHAP. 



shown by the upper somewhat irregularly curved line of 
dots. This is seen to vary from 4.4 inches to a little less 

Inches 

5 2 2 3 4 3 6 7 8 9 lO 22 22 23 14 15 26 17 18 J? 2Q $ 



2. 



I 



0. 




1 2 3 4 5 6 7 8 9 lO U 12 13 14 15 16 17 13 29 20 
Rice-hird ( Dolichonyx-oryzivorus .J 20 Males. 



Fig. io. — Diagram of Variation. 



than 5 inches. The next lower line shows the length of the 
wing of each specimen, and we at once see the want of 



vii HEREDITY, VARIATION 111 

correspondence with that of the body. No. 5, with a quite 
short body, has the longest wing of all ; while No. 1 6, with a 
long body, has nearly the shortest wing. The third line, 
showing 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 f- 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. 1 4 and 1 8 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 remark- 
able amount of variation occurs in only twenty birds taken 
at random. But the species is one of the most populous in 
North America, occurring in enormous flocks over the whole 
continent, 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 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 
diagrams of variation, showing that it occurs to an approxi- 
mately 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 account of 
these has been given by Dr. H. M. Vernon 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 : 



112 



THE WORLD OF LIFE 



CHAP. 



" Every organism varies in respect of all its characters, whatever 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." 

Referring to the diagram of human stature at p. 108, 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 percentage of mean error, and Mr. Vernon gives 
us an interesting table of the same percentage for different 
parts of the body derived from very large numbers of 
measurements of different races of men. It is as follows : — 





Per cent. 




Per cent 


Nose length . 


• 9-46 


Head length . 


. 2.44 


,, breadth . 


• 7-57 


,, breadth 


. 2.78 


„ height . 


. 15.2 


Upper arm length 


. 6.50 


Forehead height 


. 10.4 


Forearm length 


• 3-85 


Under-jaw length . 


. 4.81 


Upper leg length 


5.00 


Mouth breadth 


. 5.18 


Lower leg length 


. 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 we must lay stress upon the fact that every part 
of every organism, outside or inside, important or insignifi- 
cant, 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 develop- 
ment, varies in its different 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. 



vii HEREDITY, VARIATION 113 

This ever-present and all-pervading 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 A nimals 

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 
unoccupied 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 or 
tenfold annual increase, as among many of the higher 
animals, 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 perhaps 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 equili- 
brium has been reached everywhere, and it is only when 
some vacancy occurs, as when a tempest uproots or destroys 
a number of trees, or some diminution 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 
surviving ; and the most vigorous of these will fill up the 
various gaps that have been produced. 

But it is among the herbaceous plants that perhaps even 
greater 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. Kerner, in his 
Natural History of Plants, tells us that a crucifer, Sisym- 
brium Sophia, has been found to produce on an average 
730.000 seeds, so that if vacant spaces of suitable land 

I 



114 THE WORLD OF LIFE 

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, Sisymbrium 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 occasionally in English 
localities. 

Turning to the animal kingdom, we still find the repro- 
ductive powers always large and often enormous. 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 years, Darwin calculates that in 750 years (a few 
moments only in the geological history of the earth) each 
pair would, 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 Mr. Kearton calculates that, under the most favourable 
conditions, a single pair might in 4 or 5 years increase to a 
million. In Australia, being favourable in climate, vegetation, 
and absence of enemies, 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 
conditions 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 whole of temperate North America, being abundant in 
Pennsylvania and Kentucky, as well as over the whole of 
the central plains, while it sometimes extended to the coast 
of the Atlantic. Within the memory 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 



VII 



HEREDITY, VARIATION 



115 



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 equally powerful and ferocious with 
those of Europe, must also have been most dangerous enemies ; 




Fig. ii. — The American Bison (Bos Americamis). 



but the bisons always associated in numerous herds, and were 
so well guarded by the old males, that they appear to have 
suffered little from these animals. The immense shaggy 
covering to the head, neck, 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 quadrupeds. 

The extension of railways over the whole country about 
the middle of the century, and the fact that, as the herds 
diminished buffalo skins became more valuable, led to its 
rapid extermination ; and at the present time only a small 
and dwindling herd exists in the Yellowstone Park, and 
another in north-western Canada. 



116 THE WORLD OF LIFE chap. 

Even more remarkable has been the disappearance of 
the passenger pigeon (Ectopistes migratoria), so called from 
its great powers of flight and its migration in vast flocks all 
over North America. The population of this bird was almost 
incredibly great, as described by the American ornithologists 
Audubon and Wilson in the early part of the nineteenth 
century. It inhabited the whole of the wooded parts of North 
America from Mexico, within the tropics, to the northern 
shores of Hudson's Bay, and its former history is now the 
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 Pigeon — 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 will be both interesting 
and instructive to state briefly what were the facts as to the 
numbers of these birds about a hundred years ago (181 1). 
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 the 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 the 
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 hours 
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 



HEREDITY, VARIATION 117 

Indiana, these are generally in backwoods, and often extend in 
nearly a straight line across the country for a great distance. Not 
far from Shelbyville, in the State of Kentucky, about five years ago, 
there was one of these breeding-places which stretched through the 
woods in nearly 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 every tree was furnished with nests wherever the 
branches could accommodate them. The pigeons made their first 
appearance there about the ioth 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 with 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 roaring 
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 themselves, 
while the clothes of those traversing the woods were completely 
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 many instances I counted upwards of ninety nests 
in a single tree ; but the pigeons had abandoned this place for 
another, sixty or eighty miles off, towards Green river, where they 
were said at that time to be 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- 



118 THE WORLD OF LIFE chap. 

tory, the nearest part of which was 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 together 
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, seem- 
ing 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 pro- 
digious 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, which, 
by several gentlemen who had lately passed through part of it, was 
stated to me as several miles." 

Wilson then gives a rough calculation of the probable 
numbers 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 1 7 millions 
of bushels daily. Audubon, who went through the same 
country about twenty 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 witnessed and was informed of by many 
independent observers. Waterton, with his usual scepticism 



HEREDITY, VARIATION 119 

as to the observations of other naturalists, treats the whole 
narrative as gross exaggeration or fabrication ; on which the 
late Professor Alfred Newton 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 Newton adds that the rapid and 
sustained flight of these pigeons is as well established as 
their former overwhelming abundance, birds having been 
killed in the State of New 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 Newton 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 
North America, together with its unequalled powers of flight, 
it must be classed as one of the finest examples of what 
Darwin termed "dominant species," and may also be con- 
sidered as the highest development of the special type of 
bird-life manifested in the order Columbae 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 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-forms as the bison and passenger pigeon. 

Equally remarkable, perhaps, is the Norwegian lemming, 
a little animal somewhat larger than our short-tailed field- 
mouse, but with a tail only half an inch long. This creature 
is always abundant in Lapland and northern Scandinavia, 
but only extraordinarily 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, crossing lakes, and rivers, and even eating 



120 



THE AVORLD OF LIFE 



CHAP. 



through corn and haystacks when these cross their path. 
The following recent statement of the ascertained facts as to 
these strange migrations — from the work on Mammals by 
the late Sir H. Flower and R. 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. 




Fig. 12. — The Lemming (Myodes lemmus). 



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. When suddenly disturbed, instead of trying to escape, 



vn HEREDITY, VARIATION 121 

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.) 

" Trie 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 Norway 
and Sweden, where in ordinary circumstances they are quite 
unknown, are occasionally and at very uncertain intervals, varying 
from five to twenty 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 con- 
siderable 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, 
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 extraordinary was 
the sudden appearance of these vast bodies of Lemmings to the 
Norwegian peasants, that they supposed they must have fallen from 
the clouds. 

" The principal really ascertained facts regarding these migrations 
seem to be as follows : When a combination of favourable circum- 
stances has occasioned a great increase in the numbers of Lemmings in 
their ordinary dwelling-places, a movement necessarily 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, according 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. 



122 THE WORLD OF LIFE 

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 con- 
ditions — high plateaux within or bordering on the Arctic 
circle, with its intense cold, its long periods of darkness, 
buried in snow in winter, and with a scanty and stunted 
vegetation. Yet they appear to have a most enjoyable 
existence, and would evidently be able to overrun and 
occupy a much larger extent of similarly 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 disease or 
the attacks of enemies. 

In Mr. W. H. Hudson's most interesting volume, A 
Naturalist 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 passage 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 pre- 
datory 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 many 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 j 
Nature's silent, passionless tragedies, myriads of highly organised 



HEREDITY, VARIATION 123 

beings rising into existence only to perish almost immediately, 
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 enemies which had been attracted by their inordinate 
', numbers, 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 inorganic nature that speedy reproduction is such a safe- 
guard. When fire or flood, droughts or volcanic outbursts 
have destroyed 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 insufficient 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 " Mendel- 
ism," 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 adaptation of all living things. The pheno- 
mena upon which these theories are founded seem to me to 
be mere insignificant by-products of heredity, and to be 
essentially rather self- destructive than preservative. They 
form one of nature's methods of getting rid of abnormal and 
injurious variations. The persistency of Mendelian characters 
is the very opposite of what is needed amid the ever-changing 
conditions of nature. 1 

1 A critical examination of these theories is given 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. Poulton'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 
visualise its enormous extent, its almost endless diversity of 
form, structure, 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 
together, 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 enormous 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 examine, 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 
continuous 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 formation 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 

124 



CHAP. VIII 



CASES OF ADAPTATION 125 



the well-defined species of the best-known parts of the world 
— Europe and North America — have paid 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 Man, 
I thought it would be interesting to collect together and 
publish lists of all the species or varieties of animals and 
plants which 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 in- 
creased 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 interesting 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. No less than 20 
species of our Mosses and 27 of our Hepaticae 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 Hartert, 
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 
24 species, which have become more or less distinctly 
modified from their continental allies. These include a 



126 



THE WORLD OF LIFE 



CHAF. 



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 : — 



i. Pyrrhula pyrrhula pileata 

2. Turdus musicus clarkei . 

3. Pratincola rubicola hibernasus 

4. Garrulus glandarius rufitergum 

5. Loxia curvirostra scotica . 

6. Carduelis carduelis britannicus 

7. Motacilla flava rayi . 

8. ,, alba lugubris 

9. Parus major newtoni . 

10. ,, caeruleus obscurus 

11. ,, ater britannicus 

12. „ palustris dresseri 

1 3. ,, atricapillus kleinschmidt 

14. ,, cristatus scotica . 

1 5. Aegithalus caudatus rosea . 

16. Regulus regulus anglorum . 

1 7. Sitta europaea britannica 

18. Certhia familiaris britannica 

19. Erithacus nubecula melophilus 

20. Troglodytes troglodytes pirtensis 

21. Cinclus cinclus britannicus . 

22. Dendrocopus major anglicus 

23. ,, minor comminutus 

24. Lagopus lagopus scoticus 



British Bullfinch. 
,, Song-Thrush. 
,, Stonechat. 
„ _ Jay. 

Scottish Crossbill. 
British Goldfinch. 
Yellow Wagtail. 
Pied Wagtail. 
British Great Titmouse. 

,, Blue Titmouse. 

,, Coal Titmouse. 

,, Marsh Titmouse. 

,, Willow Titmouse. 
Scottish Crested Titmouse. 
British Long-tailed Titmouse. 

,, Goldcrest. 

„ Nuthatch. 

,, Tree-creeper. 

,, Robin. 
St. Kilda Wren. 
British Dipper. 

,, Great Spotted Wood- 
pecker. 

„ Lesser Spotted Wood- 
pecker. 
Red 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 interesting 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 adaptations to the slight but undoubted 
difference of climatai conditions which characterise our 
islands. 

In confirmation of this view, a few cases have been 
recorded in which nature has been caught, as it were, at 



CASES OF ADAPTATION 127 

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 
1 41 9, 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 differed from those of 
English wild rabbits in the supraorbital 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 instead 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 
certainly 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 
individuals, occurred quite recently. In February 1898, at 
the 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 



128 THE WORLD OF LIFE chap. 

while 64 perished. The happy thought occurred to 
Professor H. 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, were destroyed while others survived. He there- 
fore made a very minute and careful examination 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) Sise. — 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 
survived. 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 which died, by 
the considerable 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. Now the sternum is an indication of the size of the 
pectoral muscles which move the wings in flight. The 
surviving birds, therefore, were those that could fly quickest 
and longest, and this probably led to the more rapid 
production of animal heat. Another advantage would be, 
that these muscles being larger proportionally there would 
be less exposure of the internal organs to the extreme cold. 

The result of this interesting experiment is almost con- 
clusive 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 pre- 
sumed to have been the " fittest " at that particular time and 
place, were found to differ in just such characters, and in 



CASES OF ADAPTATION 129 

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 constantly denied on purely theoretical 

| grounds. 

It will perhaps make the subject a little clearer if I here 

I enumerate briefly the exact causes which must have been at 
work in bringing about the changes in the rabbits of Porto 

I 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. 

jit 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 
'abbits from which Darwin thinks they were undoubtedly 
(derived. Their numerous enemies would at first capture 
:he larger, more bulky, and slower-moving individuals, then 
:he white or black specimens, who would be more easily 
;een and pounced upon. This process, continuously acting 
or a few generations, would result in a smaller and more 
lusky-coloured race. The continuous attack persisting, the 
;ize would be again reduced, and the most agile and rapid 
n movement would alone survive. Thereafter, the nocturnal 
labit would be acquired by the day-feeders being almost 
exterminated, and owls would probably alone remain as 

K 



130 THE WORLD OF LIFE chap. 

formidable enemies. Lastly, the extreme wildness, sensitive- 
ness to danger, perhaps to noise or movement of any kind, 
would be developed, while the reduction of the supraorbital 
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 
connected 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 
(i) 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 
North America, the lemming in Scandinavia, 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 I 
geological changes were most actively at work, larger and 
more permanent climatic changes occurred, or when more 
marked diversities of soil and vegetation, with exposure to 
more severe competition, were brought about, those modifica- 
tions of the environment would inevitably result in more 
marked and more varied adaptations of form, structure, or, 
habits, bringing about what we everywhere recognise as 
perfectly distinct species. 

In the present work I do not propose to go farther intc 
this matter, which has been treated with sufficient detail anc J 
with copious illustrations in my Darwinism and other works 
as well as in Darwin's classical volumes, The Origin 
Species and Animals, and Plants under Domestication, 
will therefore now proceed to an account of some of thos 



VIII 



CASES OF ADAPTATION 131 



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 
manifestations, 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 vegetable world for its very existence. It 
is also tolerably clear, though not quite so conclusively 
proved, that it is on the overwhelming variety of plant 
species, to which we have already called attention, that the 
corresponding variety of animal species, 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 vegetables, and 
even the grass on our lawns, are in some seasons destroyed 
by 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 which often swarms in millions. Then there 
are the aphides 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 regards 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 ; 



132 THE WORLD OF LIFE 

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 in large 
quantities the plants the insect-pests feed upon 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 gardens and hedgerows, our orchards, woods, and copses 
are thronged with feathered songsters, resident and migratory, 
engaged 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 millions 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. Almost 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 supply sufficient nourishment 
in a condensed and easily digestible 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 whole days, and the results are extremely 
instructive. The chiff-chaff, for example, feeds its young 
on small grubs extracted 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 



viii CASES OF ADAPTATION 133 

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 
thousand caterpillars to the ravenous young birds, who, 
taking the average at ten (and they sometimes have sixteen), 
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 six- 
teen 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 wing. 
A flycatcher was observed to sit on a dead branch of an ash 
tree near her nest, whence by short flights she caught small 
flies, etc., on the wing, bringing a mouthful to her young 
every two to five minutes. 

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 insect-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 



134 THE WORLD OF LIFE 

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, flies, 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 
larvae 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 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 parental love, enabling them to keep up this high-pressure 
search for food, and of watchfulness of their nests and 
young, on the continuance of which, and its unfailing 
success, the very existence of those young and the continu- 
ance 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 abundant, and as omnipresent as they 
actually are ; and also unless 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 them- 
selves alone as an apparently superfluous and otherwise 
useless part of the great world of life, but are, and must 
always have been throughout long past geological ages,! 



VIII 



CASES OF ADAPTATION 135 



absolutely essential for the origination 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 vegetation, the nightingale 
and the lark, the wren, the redbreast, and the fairy-like tit 
and gold-crests 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 own country and see how birds 
fare in distant lands, we find the key to many of the secrets 
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 larvae 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 abundant in many parts of 
the tropics, yet their fullest development is to be found in 
the icy plains of the Far North, especially within the Arctic 
circle both in the Eastern and Western hemispheres. 

Sir William Butler in his works — The Wild Lone 
Land, and others on Arctic and sub-Arctic North America 
— describes them as often swarming in such abundance as to 
completely obscure the sun like a dense thunder-cloud ; 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 



136 



THE WORLD OF LIFE 



CHAP. 



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 
Seebohm, who spent two seasons there, one in the north- 
east of Russia, at Ust-Zylma, and at the mouth of the 




Fig. 13. 
Shooting Wild Geese 
on the Petchora River at Ust- 
Zylma (May 14, 1875). 



Petchora River, far within the Arctic circle ; and another in 
Northern Siberia, at the mouth of the Yenesay River. He 
tells us, that — 

" 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 
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 

1 Siberia in Europe, p. 296. 



VIII 



CASES OF ADAPTATION 



137 



to breed are two species of wild swans and the bean goose. 
So early as ioth May they began to arrive, passing over 
Ust-Zylma (Lat. 66° N.) in flocks, where, by constructing 
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, when near the mouth of 




Fig. 14. — Geese Moulting 
as they migrate South over the Tundra (July and August). 

the Petchora River, 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 
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 



138 



THE WORLD OF LIFE 



CHAP. 



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 

abundant 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-margins. 

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 Rae, with proboscis infemali veneno mnnita. I foresaw that we 
should have opportunities enough to study the natural history of 
these bloodthirsty 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 the 
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 covered 
the tundra with a mist." 



VIII 



CASES OF ADAPTATION 



139 



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 
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 was protected by 




Fig. 16. — Messrs. Seebohm and Harvie-Brown 
watching Grey Plover through a Cloud of Mosquitoes. 

india-rubber boots and cavalry gauntlets, and a carefully 
constructed cage over his head, without which he never dare 
go out on the tundra (see Fig. 15). 

Now this Arctic country, beyond the limit of forests 
and stretching to the Polar ocean, which 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 abund- 
ance of mosquitoes and their larvae that is the chief 
attraction. In Mr. Seebohm's works, already quoted, and 
in his fine volume on the Geographical Distribution of the 
Plovers and Allied Birds, he gives a most graphic account 
of this country and of the birds flocking to it, which is 



140 THE WORLD OF LIFE chap. 

worth quoting, as few people have any adequate idea of 
what the greater part of the Arctic 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 winter, 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 migratory 
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 Russia, 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 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 summer." 

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 



VIII 



CASES OF ADAPTATION 



141 



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, 
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 




Fig. 17. 

Ice breaking up on the Petchora 

River. 



even the crushing weight of water at Niagara, a force which breaks 
up the ice more than a mile wide, at least three feet thick, and 
weighted with another three feet of snow, at the rate of a hundred 
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 inhabitants 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 
of thousands of song-birds, amidst the waving of green leaves and 
the illumination of gay flowers of every hue. The transformation 



142 



THE WORLD OF LIFE 



CHAP. 



is perfect. In a fortnight the endless waves of monotonous white 
snow have vanished, and between the northern limit of forest growth 
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. 

" It is incredible how rapidly the transformation is completed. 
Twelve hours after the snow had melted the wood-anemone was in 




Fig. 18. — Midsummer on the Tundra, at the Mouth of the 

Petchora River. 



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 other 
lichens, together with the most characteristic flowers of an Alpine 
flora — gentians, saxifrages, forget-me-nots, pinks, monkshoods (both 
blue and yellow), and sheets of the Silene acaulis, 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. 



VIII 



CASES OF ADAPTATION 



143 



" 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 
migration lasted more than a month. Very little migration was 
observable till the last week in May, but during the next fortnight 
the migration was prodigious. In addition to enormous numbers 
of passerine birds, countless flocks of geese, swans, and ducks 
arrived, together with a great many gulls, terns, and birds of prey. 
During the next fortnight, from the 5th to the 19th of June, fresh 




Fig. 19. — Sudden Arrival of Birds in the Arctic Regions 
at the End of May. 



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 picture on the next page shows both nest, 
eggs, and young birds. 

In order to ascertain approximately how many species 



144 



THE WORLD OF LIFE 



CHAP. 



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 




Fig. 20. — Grey Plover's Nest and Young (Sguatarola helvetica). 



and migratory birds which breed in our own country (about 
1 80) ; 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. H. E. Dresser, who also knows these regions personally 
and has made a special study of their birds, has been so 



CASES OF ADAPTATION 145 

good as to make an enumeration of all the birds known to 
breed in the Arctic regions of Europe and Asia, and he finds 
it to be land birds 89 species, waders and aquatics 84 
species, equal to 173 in all. Considering how vast is the 
extent of the country, and how few ornithologists visit it, 
we may put the total number at at least 180, and possibly 
even 200 species. 

The great accumulation of bird-life is, however, vividly 
pictured by Mr. Seebohm, and it is clear from all that he 
says — as well as by what he does not say — that the vast 
hordes of mosquitoes must be the chief support of the 
innumerable millions of young birds which have to be fed 
here, both passerine and wading birds. Of the former, 
more than eighty species are named, including seven 
buntings, four tits, two grosbeaks, six pipits, eleven 
warblers, five wagtails, two sparrows, three woodpeckers, 
the beautiful waxwing, and a host of others, many of which 
are among our common birds. What a delight to them all 
must be this rush northward into a land of perpetual 
daylight, swarming with the most nutritious food, fruits and 
berries for the parents, inexhaustible clouds of mosquitoes — 
which Mr. Seebohm tells us are an especially large kind 
with bodies a third of an inch long — and the equal myriads 
of their larvae in every little pond or water-hole, as well as 
quantities of larger worms and larvae. The extreme dis- 
comforts as well as the cost of a journey to these far 
northern lands are so great that very few bird- or insect- 
collectors visit them, and it is not easy to obtain direct 
and accurate observations as to the actual part played 
by the myriad swarms of mosquitoes in attracting birds from 
almost every part of the northern hemisphere to go and breed 
there. Mr. H. E. Dresser, who has made a special study 
of Palaearctic 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 

L 



146 THE WORLD OF LIFE chap. 

" 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 I 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 
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 consensus 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 



I 



VIII 



CASES OF ADAPTATION 



147 



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 truly love nature will be 
able to witness one of the most wonderful illustrations of the 




Fig. 21. — The Higher Tundra. 
Stanavialachta at mouth of the Petchora River (N. Lat. 69°). 

» myriad forms and complex adaptations which the world of 
life presents to us. 
It is a significant feature of this adaptation, that of all 
the higher forms of life, birds are the most completely 
protected from the blood-sucking and irritation of mosquitoes. 
Every part of the body is protected either with a dense 
mass of plumage, or by a horny integument on the bill and 
feet, so that they are probably quite undisturbed while 
enjoying the superabundant feast nature has spread for 
them in those remote and usually repellent lands. We may 
conclude, therefore, that it is to the two special features of 
these Arctic tundras — their abundant berries preserved 
during the winter in a natural ice-house, and the myriad 



148 THE WORLD OF LIFE 

clouds of mosquitoes and their larvae — that we owe the 
very existence of a considerable 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 
summer somewhat longer ; there can be little doubt that 
the short summer with its perpetual sunshine was equally 
favourable to the production of a superabundance of vege- 
table 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 breed- 
ing 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 number 
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 marvellous 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 pheno- 
mena in the world — that of the small island of Heligoland, 
40 miles off the mouth of the Elbe in about the same 



CASES OF ADAPTATION 149 

latitude as Scarborough. Most of the migratory birds from 
Scandinavia and Arctic 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 Europe), 
is most interesting ; and I refer to it here chiefly for the 
sake of pointing 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 ob- 
served 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 were, 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 Heligo- 
land for half a century ; every resident on the island knows 
it, and Mr. Seebohm declares that there can be no doubt 
whatever about it. The inference from this fact (drawn 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 supporting 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 



150 



THE WORLD OF LIFE 



CHAP. 



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 migratory birds which rest at 
Heligoland always occur at night, and are very intermittent. 
They usually take place on dark nights, sometimes in 
millions ; at other times, a week will sometimes pass with 




Fig. 22. — The 

Lighthouse at 

Heligoland on a 

Migration Night. 



only a few stragglers. Of one such pitch-dark night Mr. 
Seebohm writes : — 

"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 birds coming and going. Nothing else was 
visible in the darkness of the night, but the lanthorn of the light- 
house 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." 



CASES OF ADAPTATION 151 

He also tells us that 15,000 sky-larks have been caught 
on Heligoland in one night ; and all agree that the count- 
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 regular 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 only half a tail, or 
some other defect. These are supposed to be mostly un- 
mated 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. 

Now, the fact of the young birds only appearing on 
Heligoland for the first week or so of the season of each 
species is easily explicable. Remembering that the autumnal 
migration includes most of the parent birds and such of 
their broods as have survived, 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 ac- 
quired the full strength of the adults, and having had little, 
if any, experience in long and continuous flights, a con- 
siderable proportion of them on the occasion of their first 
long flight over the sea, on seeing 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 doing. The 
old birds and the stronger young ones, however, pass high 
overhead, till they reach the north coast of Holland, or, 
in some cases, pass over to our eastern coasts. We must 
also remember that the longer the birds are in making the 
journey overland, the more young birds are lost by the 
attacks of birds of prey and other enemies. Hence the 



152 THE WORLD OF LIFE chap. 

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 down 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 explained 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 
marvellous developments of the vast world of life — birds 
and insects — 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 
which they have developed, suggest some very important 
considerations. 

As we might expect, both birds and insects are com- 
paratively rare in a fossil state, but there are sufficient 
indications that the latter were first developed. A consider- 
able number have been found in the Coal Measures, especi- 
ally numerous cockroaches. Ancestral forms of Neuroptera 
and Hemiptera allied to our may-flies and dragon -flies, 
bugs and aphides, are found in Devonian and Carboniferous 
rocks. The more highly 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 
jaws, the celebrated Archaeopteryx. Diptera (flies) are also 
found here, as well as a wasp, somewhat doubtfully identi- 
fied ; while the most highly developed of all insects in 
structure and metamorphosis, as well as in size and beauty, 
the Lepidoptera, are first found in Tertiary beds, at a time 
when birds allied to living forms also first appeared. 

This general parallelism of development seems clearly 



CASES OF ADAPTATION 153 

to indicate that birds, in the full and varied perfection in 
which we now find them, are dependent on a correspondingly 
widespread 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 succes- 
sively become specialised to capture and feed on them. 
The early birds with toothed jaws were able to feed upon 
the cockroaches and ancestral Neuroptera 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 (Musci- 
capidse) and the totally distinct American fly-catchers or 
tyrant birds (Tyrannidae), 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 
woodpeckers 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 
irger and more varied insect-forms of those countries, so 
lat it may be safely concluded that no group of the vast 
issemblage of insects but what has its more or less dangerous 
enemies among the birds. Even the great rapacious birds, 
the hawks, buzzards, 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 fruits and seeds often 



154 THE WORLD OF LIFE 

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, stone- 
chats, tits, wagtails, 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 varia- 
tions, 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 superior acuteness in any 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 inorganic 
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 difficulty whatever in accepting the " origin of 
species " from other species as a demonstrated fact ; and 
this alone was the hitherto insoluble problem which 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 development, that difficulties 



CASES OF ADAPTATION 155 

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 intermediate 
stages either through the investigations of embryologists, or 
of palaeontologists, so that many of the greatest difficulties 
of Darwin's early opponents have quite disappeared. Some 
of these recent explanations have been referred to already, 
and many others are briefly described in my Darwinism. 
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 
suggestions beyond the scope of Darwin's work, and which, 
I think, have not been sufficiently considered by later writers 
on evolution. 









CHAPTER IX 

THE IMPORTANCE OF RECOGNITION-MARKS 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 incidentally ; 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 inedible 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 attention ; but, after many years' consideration of 
the whole problem of evolution I have come to the con- 
clusion that, of all the causes of distinctive marking 
(among the higher animals 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 abso- 
lutely essential as a factor in the evolution of new species 
that I here devote the larger part of this chapter to their 
consideration. 

156 



RECOGNITION-MARKS 157 

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 
majority of birds while sitting on their nests, the sand- 
coloured desert animals, and the prevalence of green colours 
in the inhabitants of tropical forests, are a few of the best- 
known examples. 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 markings occurred which could not by 
any possibility be interpreted as protective, because they 
seemed to render the creature glaringly conspicuous. Some 
of these, which were most prevalent 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 with 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 possess these protective 
qualities, yet acquired the same colours and often the same 
r orm ; and when my fellow - traveller on the Amazon, 
JH. W. Bates, showed how this peculiar kind of " mimicry " 
vas beautifully explained on the Darwinian hypothesis, not 
3nly was the theory itself greatly strengthened, but a whole 
lost of curious and beautiful colour-phenomena in nature, 
litherto unnoticed, were seen to come under some form of 
he same general principle. As one rather extreme example 
)f mimicry I give the figures of a black wasp with white- 
handed wings, which is closely imitated by a heteromerous 
jeetle. These I captured myself in the forests of Borneo, 
lying together near the ground. They are of nearly the 
ame size. The wing- coverts (elytra) of the beetle are 
educed to pointed scales, allowing the true wings to be 
'.lways extended. This is most unusual in beetles, as is the 



158 THE WORLD OF LIFE 



CHAP. 



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 being mistaken for the wasp. Of course, this 
change is the result of a very long series of slight modifica- 
tions of the beetle, each bringing it a little nearer to the 
wasp, a series extending probably through thousands or even 
millions of generations. 1 

Recogn ition -Marks 

But though the subject of " mimicry " involves problems 
of extreme complexity and interest, and has therefore 
attracted 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 world 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 while determining the species, 
I could not help observing in many of them the varied 
and 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 conspicuousl) 
by white bands, sometimes across the middle of the tail 
sometimes at the end, sometimes with one band, sometime: 
with two or even three, so that the species were easily dis 
tinguished by this one character. But the chief peculiarit) 

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 shouli 
read Professor Poulton's elaborate papers in the Transactions of the Entomologies 
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. R. Shelforc 
on mimetic insects from Borneo, and as these are illustrated by coloured plate 
and deal with cases of the same nature as the one here given, they are ver 
instructive. (See Proceedings of the Zoological Society of London, Nov. 4, 1902 

1 
I 




Wasp. 



Beetle. 



LMycnimia aviculus. 
2.c0l0b0rh0mbus fasciatipennis. 



Fig. 23.— Mimicry of Wasp by a Beetle. 



RECOGNITION-MARKS 159 

to be noticed was, that these bands were only seen during 
flight, the white markings being quite invisible when the 
birds were at rest The importance 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. 

Now that we have learnt how rapid are the powers of 
increase 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 recognise their own species from all others without fail 
and at considerable 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 approaching from behind or from the front ; while the 
separate portions 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 new species by adaptation to change of condi- 
tions, as will be shown later on. 

I first gave a somewhat full account of this class of 
markings, with several characteristic illustrations, in my 
Darwinism, in 1889; but I had briefly treated the subject 
in my 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 think I was the first to claim 
for it a high place among the factors concerned in animal 
svolution. The clearest and most picturesque illustration of 
the subject I 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 
mportant passage : — 

" The common jack-rabbit x when squatting under a sage-bush 



1 This appears to be the common grey hare (Lepus americanus). 



160 THE WORLD OF LIFE 



CHAP. 



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 
difficult 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 jack-rabbit. 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-rabbit, 
and saves it much pains to escape from real or imaginary dangers. 
As soon as it squats again all the directive marks disappear, and the 
protective gray alone is seen. In the bird-world the same general 
rule applies. When sitting, birds are protectively coloured ; when 
flying, directive ly." 

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 scattered 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 markings are usually con- 
fined 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. 1 I have also come to the conclusion 
that the horns of these animals, though primarily developed 

1 The beautiful gazelle figured in my Darwinism (p. 219) shows both these 
kinds of markings very strongly ; while an examination of the numerous figures 
of antelopes in Wood's Natural History (or in any of the more recent illustrated 
works) affords numerous examples of them. 



1 







Fig. 32. 
cobus leche. 




Fig. 34- 

co bus maria. 



Recognition-Marks in African Antelopes 






Fig. 2S. 
Strepsiceros kudu, 



Fig. 29. 
Strepsiceros jmberbis. 








Fig. 30. 

BUBALIS JACKSOXI. 



Fig. 31. 
sEpyceros melampus. 



Recognition-Marks in African Antelopes. 





Fig. 24. 
Tragelaphus stekei. 



Fig. 25. 
boocercus euryceros. 




Fig. 26. 

Gazella GRANTI. 




Fig. 27. 
Gazella walleri. 



Recognition-Marks in African Antelopes. 






RECOGNITION-MARKS 161 

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 modifications 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 recogni- 
tion 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 
guiding 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 
at the top, which, with a general likeness of form, possess 
individuality both in face-marks and in the curvature of the 

I horns ; while the two gazelles at the bottom are still more 
distinct. The second 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. The third 

I group consists of three species of the genus Cobus, in 
which the horns are each so distinct in size and curva- 
ture as to be easily recognisable at considerable distances ; 
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. 

Now, as the antelopes are very closely allied to each 
other, both in structure and external form, it seems im- 
probable that all the diversities in the horns (which are 

M 

I 






162 THE WORLD OF LIFE 

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 especially serviceable while in motion, it 
seems quite natural that the horns should have been modified 
to serve the same purpose while the animals are at rest, or 
when their bodies are wholly and their faces partially con- 
cealed 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 
described in Chambers's Encyclopaedia : 

" 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 
production of a distinctive white patch on a prominent part 
of the body, which patch is concealed when not required and 
when it might be dangerous, and only exhibited in the 
presence of some real or imaginary danger, for the spring- 
bok 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 be seen, than even our 
rabbit's upturned tail when running, which has been termed 
the " signal flag 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 feeding, 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, whuase ranges, 



IX 



RECOGNITION-MARKS 



163 



sometimes overlap, and which are no doubt descended from 
a common ancestor. The head of each exhibits different 




Fig. 36. — CEdicnemus grallarws (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 denned white 
spot on the wing and its more conspicuous markings on the breast. 

markings, by which they can be easily distinguished while 
feeding on the ground ; while the bolder markings on the 




Fig. 37. — CEdicnemus 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 
between those of the other two species. 

wings enable them to keep together during their wanderings 
m migrations (Figs. 36, 37, and 38). 



164 



THE WORLD OF LIFE 



CHAP. 



Markings of this character, though varied almost in- 
finitely, occur in all classes of the higher animals, and very- 
much in proportion as their mode of life requires them. 
When concealment is of more importance, then the recog- 
nition is made effective by differences of shape or of motions 
and attitudes, or by special cries, as in the cuckoo. Among 
the birds of the tropical forests, while the ground colour is 
often protective, as in the green of parrots, the smaller fruit- 




Fig. 38. — QLdicnemus 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. 



pigeons of the Malay Archipelago, many of the barbets, and 
hosts of other birds, yet the different species will be almost 
always characterised by 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 grow upon their branches, the general 
effect is by no means conspicuous. 

Now, 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 endless diversity of colour and marking, when not pro- 
tective, seems difficult to explain. The Duke of Argyll, in 
his interesting work, The Reign of Law, published six years 



RECOGNITION-MARKS 165 

after the Origin of Species, expressed this objection very 
forcibly. After describing 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 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 which 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 organisms." 

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 
recognition or as preventing intercrossing between incipient 
species, a sufficient cause for all such conspicuous indications 
of specific diversity as are found pervading the whole vast 
world of life. It now only remains to point out how these 
markings 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 objection to the whole theory of recognition-marks. 

An Objection to Recognition- Marks answered 

In a book on Darwinism and Lamarckism, the late 
Captain Hutton, a well-known New 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 



166 THE WORLD OF LIFE chap. 

other bird on the same island for which they could possibly 
be mistaken. He then says : 

" Consequently it appears certain that most of these species were 
developed singly, each in its own island. If this be the case, 
the colours which now distinguish the different 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 which are found in all the islands 
around New Guinea and in the Western Pacific. He urged 
that the various peculiarities of colour cannot be useful as 
recognition-marks, because the colour and markings of each 
of the genera 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 two possible suppositions — either the species 
originated in island 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 contem- 
plated, let us see exactly what must have happened. 

We know as a fact that, when any species reaches an 
island 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 New Zealand and Porto 
Santo, the sparrow in the United States, and many others, 
are examples of such rapid increase. But as soon as the 



ix RECOGNITION-MARKS 167 

island is fully stocked, a number equal, or nearly so, to the 
annual increase must die off every year, and these will inevit- 
ably 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 inter- 
crossing 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 variation of colour in those better adapted will be 
advantageous, will lead to more rapid change, and will thus 
come to characterise 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 they 
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, which may have occupied scores 
or hundreds of generations, some outward sign of the 
structural 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 distinc- 
tive 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 interbreeding with the 
less-adapted immigrant. 

Recogtiition by Butterflies 

This case shows how easy it is to make mistakes or 
arrive at wrong conclusions, unless we take account of all the 
details of a problem, and endeavour to follow out the exact 



168 THE WORLD OF LIFE chap. 

processes 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 
erroneous, 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 assumed, 
without going into details, that the theory of " recognition- 
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, 
especially 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 world to care for them- 
selves they are thoroughly acquainted with the difference 
between 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, every- 
thing 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, by sight, which 
are of its own race. It must be remembered that from the 
position of its eyes it cannot see itself except at so oblique 
an angle as to be almost useless ; and when we consider the 
extreme diversity of 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 some- 
thing analogous to it. It is also known that the males of 
many 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 



RECOGNITION-MARKS 169 

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 
i 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 
differentiation 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 utilised for securing the safety of the perfect insect to a 
sufficient extent to provide for the continuance of the race, 
thus keeping up that endless variety of form and colour 
which is, perhaps, one purpose of their existence. 

The first great adaptation here, as throughout nature, is 
to secure concealment 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 insect is at rest. Great numbers are also 
deceptively coloured by eye-marks (ocelli), which resemble 
'he eyes of mammals in such a way as to be very striking in 
:he mingled light and gloom of the forest and in the general 
mrroundings of each species. Large groups in all the 



170 THE WORLD OF LIFE 

tropical regions possess warning 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 insect-eating creatures. 

Those which are protectively or deceptively coloured on 
the exposed portions of their wings often exhibit the most 
brilliant or gaudily contrasted colours elsewhere ; 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 
expanse of the wings is itself an additional protection by 
diverting attention from the body ; and it has thus become 
possible, without 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 New Guinea — the three most productive 
regions in the world for butterflies (and also for birds) of 
resplendent hues and in endless variety. 

A new Argument 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 
insect 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 Fertilisa- 
tion 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 al. 
the commoner butterflies visit a great variety of honey, 
bearing flowers without much regard to colour. Thus 
Argynnis papJiia visited flowers of four different natura 
orders, whose flowers were white or pale red ; the largi 



IX 



RECOGNITION-MARKS 171 



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 insects anything 
more than the power to recognise, after experience, any 
conspicuous flowers that produce pleasant odours and, usually, 
accessible honey. 

A consideration of the whole evidence as to the pur- 
pose served by the excessively varied and brilliant colora- 
tion of butterflies 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 deposition of her eggs, and the 
still shorter period needed for the special functions of the 
more brilliantly coloured male together with his power of 
irregular but rapid flight, render it possible for the colour- 
development to attain a degree of variety and beauty beyond 
that of all other living things. The larvae of Lepidoptera 
I in their countless myriads undoubtedly constitute an im- 
portant factor in supporting the gloriously varied bird-life 
of the tropics, as we have seen that they so largely support 
that of our temperate zones. 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 
I approximately equal supply of larvae 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 primarily a still more important function, that of 
facilitating 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 identification as already described. That this is the 



172 THE WORLD OF LIFE chap. « 

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 now unnecessary though they were of the 
highest importance 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, 
primarily, recognise each other by sight, but by some sense 
analogous to that of smell. This seems now to be almost 
certain, and it affords the explanation of what would other- 
wise be a great difficulty, how the males of polymorphic 
females, as in Papilio p amnion in the East and Papilio teneas 
in the West, numerous American Pieridae and many other 
groups, in which the females are coloured as if with the 
purpose of being as unlike 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 knoivn method of mutual recognition by Lepi- 
doptera is by scent, explains the whole difficulty. The 
colours and markings of these insects have been produced in 
adaptive relation to their enemies almost 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 
afforded (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 EARTH'S SURFACE-CHANGES AS THE CONDITION 
AND MOTIVE-POWER OF 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 
number of examples that these factors are omnipresent 
features of organic life, only varying somewhat in the pro- 
portions of their occurrence in different species, we are now 
prepared to indicate the conditions under which they have 
acted in the production 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 con- 
siderable changes occur in the inorganic world, the effect 
produced by the constant interaction between species and 
species, or between plants and animals, results in changes of 
local distribution 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 be 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 
:hanges in numbers, and by the local distribution of the 
slightly altered numbers. Once such an equilibrium is 
ittained, there seems no reason why it should not be 
permanent. Natural selection would keep up the sufficient 
idaptation of each species, but would not tend to change 
:hem. 

Geology proves that the inorganic environment — the 

173 



174 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 there- 
fore 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 j 
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 I 
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 
component 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 distance 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 o 
view is, that almost every mountain-range on the eartl 
presents us examples of such stratified rock-strata, often wit? 
abundant fossils of marine animals, at enormous height; 
above the sea-level. Such are found in the Alps at 8ooc 
feet, in the Andes at 14,000 feet, and in the Himalayas a 
16,000 feet elevation. Innumerable cases of marine fossils a 
lesser heights are to be found in every part of the world, anc 



)■ 



x EARTH-CHANGES & EVOLUTION 175 

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 exceed- 
ingly 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, 1 and is generally accepted by geologists as of great 
value. The surplus 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 measure- 
ments have been very carefully made for a number 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 I foot in 6000 years. 
Ganges 



)) 


VJCXUg^O 


J5 


)» 


H 


^5° 


J) 


Hoang-Ho 


>> 


») 


1 


1464 


)) 


Rhone 


)) 


>) 


» 


I528 


)» 


Danube 


?> 


)) 


I) 


6848 


>> 


Po 


1) 


)") 


>) 


729 



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 pro- 

1 See Phil. Mag., April 1853. 






176 THE WORLD OF LIFE 



CHAP. 



portion of lowland 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 consequence lowers the land perhaps more 
rapidly than any important river on the globe. On the 
whole, we may take these rivers as fairly representative. 
Their mean rate of denudation 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 we can even see and hear the process con- 
tinually going on. Under every precipice there is a more 
or less extensive 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' down- 
pour of rain, innumerable trickles of muddy water course 
down in every direction ; while every streamlet or brook — 
though usually of water as clear as crystal — becomes a rapid 
torrent of mud-laden water. It is by a consideration of 
these every-day phenomena in operation over every square 
yard of thousands of square miles of surface that we are able 
to understand and 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 thousand years ago, we should see that in 
many places the whole contour and appearance of the 
surface was changed. 



i EARTH CHANGES & EVOLUTION 177 

When this mode of estimating the rate of subaerial 
denudation was first applied to well-known regions, geolo- 
gists themselves were surprised at the result. For I foot 
in three thousand years is IOOO feet in three million years, a 
oeriod which has always been considered very small in the 
scale of time indicated by geological changes. When we 
;onsider that the mean height of all Europe (according 
:o a careful estimate by Sir John Murray) is a little under 
tooo feet, we find, to our astonishment, that, at the average 
ate of denudation, the whole would be reduced almost to 
;ea-level in the very short period of three million years, 
vhile all the other great continents would be reduced to 
he condition of " pene-plains " (as the American geologists 
erm it) in about six or eight million years at the utmost. 
t is quite certain, therefore, that there must be some counter- 
cting uplifting agency, either constantly or intermittently at 
/ork, to explain the often-repeated elevations and depressions 
If the surface which the whole structure and mechanical 
•jxture of the vast series of distinct geological formations 
'ith their organic remains, prove to have taken place. 

The exact causes of these alternate elevations and 
epressions, sometimes on a small, sometimes on a gigantic 
rale, have not yet been satisfactorily explained either by 
2ologists or physicists. Two of the suggested causes are 
ndoubtedly real ones, and must be constantly acting ; but 
is alleged by mathematical physicists that they are not 
•lequate to produce the whole of the observed effects. They 
- e both, however, exceedingly interesting, and must be 
Hefty outlined here. We require first, however, to trace 
ut what becomes of the denuded matter that lowers the 
ontinental surfaces at so rapid a rate, and is poured into 
1e sea at various points around their coasts ; and this is the 
iore necessary because recent researches on this matter 
l.ve led to results as surprising as those of the measurement 
c the amount of denudation by rivers. 

During the voyage of the Challenger round the world for 
te purpose of oceanic exploration, not only was the depth 
c the great oceans determined by numerous lines of sound- 
ijs across them in various directions, but, by means of 
ii^enious apparatus, samples of the sea-bottom were brought 

N 



178 THE WORLD OF LIFE 

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 re- 
searches showed that this idea was almost as remote as 
possible from the truth. The actual facts are, that the whole 
of the land debris, with a few special and very minute ex- j 
ceptions, are being deposited on the sea-bottom very near 
the shore, comparatively speaking, and all but the very finest 
material quite close to it. Everything in the nature of 
eravel or sand, of which so much of the rockv 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 ; while 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. Agassi2 
also, has found that the extremely fine mud of the Mississippi 1 
River is never carried to a greater distance than 100 mile.' 
from its mouth. If we take even so much as 50 miles foil 
the average distance to which the denuded matter is carried 
we find the whole area of deposit around South America t<; 
be 60,000 square miles. But the area of that continent i.| 
about six million square miles, so that deposition goes 01 
about a hundred times as fast as denudation : while ove' 
considerable areas where the deposits are of a sandy rathe 
than of a muddy or slaty nature, it may go on a thousand 
times as fast. This is a most important fact which does nc 
appear to have been taken into full consideration by geologisl 
even to-day. 

The correlative fact as to the ocean bed is, that over th 
whole of it, when more than the above-named distances froi; 
land, what are called " deep-sea oozes " are found. The.'! 
are formed almost entirely by the calcareous or silicioi 






x EARTH CHANGES & EVOLUTION 179 

skeletons 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 animals are found, especially the otoliths (or ear bones) 
of whales and the teeth of sharks. And the extreme slow- 
ness of the deposit of these oozes is shown by the fact that 
it is often impossible 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 organic 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 main- 
tained by many rather illogical writers) the epoch of sub- 
mergence would be indicated by some fragments, at least, of 
the consolidated ocean ooze which must once have covered 
the whole continental area. 1 

Thickness of the Earth's Crust 

We now have to consider a quite different set of pheno- 
mena 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 every 47I 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 
:ountries furnish an additional proof of the high temperature 
if the interior. Below the depth above indicated there 
vould probably be some miles of rock in a plastic state, 
vhile irregularities would result from the nature of the rock, 
ome being more easily melted than others. 



11:3 



1 For a full discussion of this question see my Darwinism, chap. xii. ; Island 
ife, chaps, vi. and x. ; and Studies Scientific and Social, vol. i. chap. ii. In 
lis last work the whole argument is summarised and the numerous converging 
nes of evidence pointed out. 



180 THE WORLD OF LIFE 

Now, 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 diminished, not only by the amount due to 
the mass of the mountain itself, but to about double that 
amount. This is so universally 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 support 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 thickness must occur below 
to keep it in equilibrium. 

Thus are explained the very frequent phenomena of i 
horizontal 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 subsidence. Exactly similar phenomena; j; 
occur through the whole series of the geological formations 
to the most ancient ; in some cases strata eight miles ir 
thickness showing proofs that the very lowest beds were nol 
deposited in a deep ocean, but in quite shallow water neai 
shore. 1 

Now, as we have seen that, over many areas not far fron 
shore, deposition may occur 100 or even 1000 times a 
fast as denudation, and that this same area is continuousl; 



:: 



^; : 



1 In chapter iii. of vol. i. of my Studies Scientific and Social I have give 



details of these phenomena on the highest geological authority. 



II 



x EARTH CHANGES & EVOLUTION 181 

lowered by the weight forcing the crust downwards, we have 
a real and efficient cause for continuous subsidence and the 
formation of parallel strata of enormous thicknesses. It 
remains to account for the subsequent upheaval of these 
areas, their tilting up at various angles, and in many cases 
their being fractured, 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 frequent outbursts of red-hot ashes or liquid lavas 
from volcanoes. 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 
temperature determined by solar heat, and also because the 
temperature at which the rocks become liquid is tolerably 
uniform, 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 interior, 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 unequal strength and tenacity, the 
actual results will be exceedingly unequal, and the in- 



182 THE WORLD OF LIFE chap. 

equalities 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. Now, the ocean floors are enormous plains, 
except that they have, here and there, volcanic islands rising 
out of them. The water which covers them preserves uniform 
temperature, which, at the bottom, is not much above the 
freezing point of sea-water. We may conclude, therefore, 
that they are very nearly stable. Pendulum experiments 
show that the crust below these oceans is more dense than 
the subaerial crust, due, probably, to the uniform pressure 
and temperature they have been subject to for geologic 
periods. We may assume, therefore, that they do not be- 
come crumpled or distorted by the contraction of the liquid 
earth beneath them. The great plains of Russia, 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 
upheavals that could be produced by a shrinking crust at 
probable 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 differ- 
ences of height of the land surfaces. But if, as the Rev. O. 
Fisher 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 Darwin 
and accepted by Sir Robert Ball ; and if the whole wrinkling 
effect of contraction is concentrated on a few lines or areas 



x EARTH CHANGES & EVOLUTION 183 

of weakness, always near existing mountains ; and further, 
if this cause of elevation be supplemented by the con- 
tinual subsidence of large areas along the margins of all the 
continents by the weight of new deposits producing a pres- 
sure on the liquid interior, which must result in upward 
pressures elsewhere, then it seems possible that a combina- 
tion of these causes may be sufficient. 

Yet another cause of elevation has recently been demon- 
strated. After many unsuccessful attempts, the actual 
existence of semi - diurnal lunar tides within the earth's 
interior has been proved ; and such tides must, it is said, 
generate a vast amount of heat, culminating at the bi-monthly 
periods of 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 cumulative results would, therefore, add to the 
upward forces produced by contraction along lines of weak- 
ness. 1 

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 sur- 
face is undoubted. The most general phenomenon seems 
to have been the very slow elevation of great beds of strata, 
deposited one above another along the coasts of a con- 
tinental mass, or sometimes along the shores of inland seas ; 
immediately followed by a process of denudation of this 
surface by rain and rivers, which, as the elevation con- 
tinued, carved it out into a complex series of valleys and 
ridges till it ceased to rise farther. The denudation con- 
tinuing, 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 repeated 
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 

1 This sketch of the internal structure of the earth, as affecting elevation and 
depression of its surface, is fully discussed in Mr. O. 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. 



184 THE WORLD OF LIFE 

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 removed by denudation, the folded 
strata were themselves exposed to further denudation, and 
all the strange peaks and ravines and rushing cataracts of 
alpine mountains became revealed to us. 

Thus, in alternate belts or more extended areas, our 
continents have been, step by step, built up throughout the 
ages, with repeated alternations of sea and land, of mountain 
and valley, of upland plateaux 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 eccen- 
tricity of the earth's orbit and the precession of the equinoxes, 
leading 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. 1 

Long Persistence of the Motive Power thus caused 

It is in this 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 uni- . 

1 See my Island Life, chapters vii., viii., and ix., for a full discussion of the 
causes and effects of glacial periods. 



x EARTH CHANGES & EVOLUTION 185 

formly, 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 alternately 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 lowered by denudation towards the sea-level, 
and part by part is always sinking below it, yet ever being 
renewed by elevatory forces, whose nature and amount we 
can only partially determine. 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 completely severed. If, on the other hand, 
the earth's surface had ever reached a condition of per- 
manent 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, wanting 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 
adaptations 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 
s a very different matter. That conclusion seemed to many 
t>f my readers, including some astronomers, geologists, and 
physicists, to be incontestable. The addition of the present 
series of adaptations, whose continuance throughout the 
vhole period of world-life history is necessary as furnishing 
he motive power of organic development and adaptation, 
lot only increases to an enormous extent the probability 
igainst the development of a similar " world of life," cul- 



186 THE WORLD OF LIFE chap. 

minating in man, in any other known or reasonably conjec- 
tured planet, but affords, in my opinion, an exceedingly 
powerful argument for an overruling MlND, which so ordered 
the forces at work in the material universe as to render the 
almost infinitely improbable sequence of events to which I 
have called attention an actual reality. 

Terrestrial Temperature-A 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 only 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 
adjustments, which, during many millions of years, have 
preserved the earth's surface within those restricted ranges of 
temperature which are compatible with an ever-increasing 
development 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 
elevation 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 
by solar radiation and the conservative effect of our moisture- 
laden atmosphere, which again depends for its chief conserva- 
tive effect on the enormous extent of our oceanic areas. 



j 
I 



x EARTH CHANGES & EVOLUTION 187 

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 countless 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. 



CHAPTER XI 

THE PROGRESSIVE DEVELOPMENT 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 
endeavour 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 pre- 
ceding chapter I have endeavoured to indicate the forces 
that have been at work in continually moulding and remould- 
ing the earth's surface ; and have argued that the frequent 
changes of the physical environment 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 necessary 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- 
development, it is necessary to learn how vast, how strange, 
and yet how gradual were those changes ; how they consisted 
of alternate 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 " 

188 






ch.xi THE GEOLOGICAL RECORD 189 

in the geological record which separate the great " eras " and 
"systems" of the geologist. These phenomena are admir- 
ably explained in Professor James Geikie's attractive and 
well -illustrated 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 exhibited 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 geo- 
logists were beginning to obtain some detailed knowledge 
of the earth's crust and its fossils, and arrived at a first rude 
division into primitive, secondary, and tertiary formations. 
The first were supposed to represent the epoch before life 
appeared, 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 
living 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 
nineteenth century, the three divisions were more precisely 
limited — the first or " Primary," as containing the remains of 
Mollusca, 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 Mammalia of all the chief types now existing, with 
others of new and apparently primitive forms, or serving as 
connecting links with living groups. 

It is a very remarkable fact, not sufficiently 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 
extremely scanty as compared with what it is now, should 
still be in universal use among the geologists of the world. 
The exact limits of each of these great divisions have been 



190 THE WORLD OF LIFE chap. 

more accurately determined, but the abrupt change in the 
life-forms, and the world-wide unconformity in the stratifica- 
tion on passing from one division to the other, are as great as 
ever. The Primary or Palaeozoic period is still that of fishes 
and Amphibia ; the Secondary or Mesozoic, that of reptiles, 
in amazing abundance and variety ; and the Tertiary or 
Cainozoic, 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 
reptiles 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 New 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 ornithorhynchus 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 what was known as the 
dirt-bed of the Purbeck (Jurassic) formation at Swanage ; 
others in the Stonesfield Slate of the same formation ; and at 
a later period very similar remains were found in beds of the 
same age (and also in the Cretaceous) in North 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 
geological record, that although they occur through the 
whole range of the Secondary period, from the Trias to the 
Cretaceous, their remains are still exceedingly scanty, and 
they appear to have made hardly any structural progress in 
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. 



THE GEOLOGICAL RECORD 191 

Either there is no record of the missing links in the 
Secondary 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 
dying out of numerous groups of gigantic reptiles and the 
development 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 any 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 
separately, in order to form some conception of the changes 
in the world of life which characterised each of them. 

The Primary or Palceozoic Era 

The Palaeozoic differs from the two later eras of 
geology in having no known beginning. The earliest fossils 
iare 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 already developed into the four great 
classes, lamellibranchs, pteropods, gasteropods, and cephalo- 
pods ; while some groups of the highly organised crustaceans 
were abundant, being represented by water-fleas (ostracods) 
and numerous large and varied trilobites. Besides these, 
:he curious Molluscoidea were fairly abundant, Terebratulae 
low first appear, and, as well as the genus Lingula, have 
:ontinued to persist through all the subsequent ages to the 
oresent time. Great masses of rocks stratified and un- 
ratified exist below the Cambrian, but have mostly been 
netamorphosed by internal heat and pressure, and contain 
10 recognisable organic remains. 

Geologists have been greatly impressed by this sudden 

ppearance of marine life in such varied forms and com- 
paratively high organisation, and have concluded that the 

tratified formations below the Cambrian must probably have 



192 



THE WORLD OF LIFE 



CHAP. 



equalled the whole series which we now know above it. 
Dr. Croll declared, that " whatever the present mean thick- 
ness of all the sedimentary rocks of our globe may be, it 
must be small in comparison with the mean thickness 
of all the sedimentary 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." l This view was 
supported by Sir Andrew Ramsay, 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." 2 

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. 

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 
Cambrian ; 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. They are of strange forms and 
low type, mostly covered with a kind of plate-armour, and 
apparently 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 illustration (Fig. 39) shows one of the simpler 

1 Origin of Species, 6th ed. p. 286. 2 Proc. Roy. Soc, 1874, p. 334. 



XI 



THE GEOLOGICAL RECORD 



193 



forms, the whole surface being covered with small quad- 
rangular flattened tubercles. The tail is somewhat twisted 
to show the bi-forked character. The mouth must have 




Fig. 39. — Thelodus scoticus. 
From Upper Silurian, Lanarkshire. Half nat. size. (B.M. Guide.) 

been an aperture underneath the head. Good specimens of 
these are rarely preserved. 

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.) 

ire united into plates and scales, while the head is covered 
,vith a dorsal shield, often terminating behind in a spine ; 
ind there is often a smaller shield beneath. A separate 
)iece forms a projecting snout. 




Fig. 41. — Cephalaspis murchisoxi. 
From Old Red Sandstone of Herefordshire. About half nat. size. 

(B.M. Guide.) 

The shields of these fishes are often preserved, while the 
Dmplete body is very rare. 

Another group (Fig. 41) has the head shield continuous 

O 



194 



THE WORLD OF LIFE 



CHAP. 



or in two pieces, while the skin-tubercles are united into 
vertical plates on the sides of the body, as in the species 
here shown, 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 representing the four limbs of reptiles and 
mammals. The earliest 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.) 




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 jfc^ 
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- 



THE GEOLOGICAL RECORD 195 

tions prevailed throughout the Palaeozoic and most of the 
Secondary 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 externally, 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 extremely 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 appear- 
ance 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 

numerous forms of arthropods, insects, primeval fishes 

ind amphibians, comprises a thickness of stratified rocks 

somewhat greater than that of the whole of the Secondary 

md Tertiary strata combined. This thickness, which can 

:>e measured with considerable approach to accuracy, is 

generally supposed to afford a fair proportionate indication 

)f the lapse of time. 

There is a popular impression that in these remote ages 
he forces of nature were more violent, and their results 
nore massive and more rapidly produced, than at the 
•resent time ; but this is not the opinion of the best 
eological observers. The nature of the rocks, though often 
hanged by pressure and heat, is in other cases not at all 
ifferent from those of subsequent ages. Many of the deposits 
; ave all the characters of having been laid down in shallow 



196 THE WORLD OF LIFE 

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 Palaeozoic 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 compressed into coal- 
seams, usually of several feet in thickness. 

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 vegetation 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 thickness ; 
while the later coal-fields are never of such world-wide 
distribution. It seems certain, therefore, that at this 
particular epoch there were some specially 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 valleys of the chief great rivers ; and the special 
conditions were, probably, a high and uniform temperature, 
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 
necessary precursor of the subsequent rapid development of 
terrestrial and aerial animal life. A dense and moisture 
laden atmosphere, obscuring the direct rays of the sun, 
together with 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 



c 



THE GEOLOGICAL RECORD 197 

magnificent culmination 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, 
' we must postulate 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. No other view yet suggested affords any 
adequate explanation ; but this vast problem will be more 
fully discussed later on. 

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 because the object here is to show reasons for consider- 
ing it as essentially preparatory for that wonderful and 
apparently sudden burst of higher life-development of which 
we will now endeavour to eive some account. 



t>* 



The Mesozoic or Secondary Formations 

When we pass from the Palaeozoic to the Mesozoic era 
Are find a wonderful change in the forms of life and are 
ransported, as it were, into a new world. The archaic 
ishes wholly disappear, while the early Amphibia (Laby- 
inthodonts) linger on to the Trias, their place being taken by 
rue reptiles, which rapidly develop into creatures of strange 
orms and often of huge dimensions, whose skeletons, to the 
ininstructed eye, might easily be mistaken for those of 



198 THE WORLD OF LIFE chap. 

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 Therio- 
morpha (or " beast-shaped " reptiles), which show some rela- 
tionship to true mammals which so quickly followed them in 
the lowest of the Mesozoic strata. 

These early reptiles already show a large amount of 
specialisation. 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 discovered in the Karoo formation of the Cape Colony, 
but have been found in a few places in India, Europe, and 
North America, always either in the highest Primary 
(Permian) or lowest Secondary formation (Trias). Remains 
of allied forms have been found in the north of England and 
in the Trias of Elgin, Scotland. Their nearest surviving 
relatives are supposed to be the monotremes (echidna and 
platypus) of Australia, yet 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 may have been of subterranean habits. In the same 
formation other allied but much smaller species were found. 

Along with these were 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. 




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XI 



THE GEOLOGICAL RECORD 



199 



The two skulls here figured (Figs. 46 and 47) are of 
very different forms, and must have belonged to animals 
about the 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 




Fig. 46. — Dicykodon lacerticeps (Order — Anomodontia). 
From Karoo formation (Trias), South Africa. One-third nat. size. 

(B.M. Guide.) 

America were equally well supplied with these strange 
reptiles. In Europe till recently only a few isolated bones 




Fig. 47. — sElusaurus fblinus (Order — Anomodontia). 
From Trias (South Africa). Two-thirds nat. size. (B.M. Guide.) 

or fragments of skulls had been discovered, but about five 
or six years ago a rich deposit was found on the banks 
of the river Dwina in Northern Russia. In a large fissure of 
the rocks quantities 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 



200 THE WORLD OF LIFE chap. 

spot, found that each of these nodules contained well-pre- 
served fossils of extinct animals, 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 sometimes 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 exploration by the aid of a grant from the 
Imperial Academy of St. Petersburg. The nodules are 
taken to Warsaw, where they 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 (abundantly preserved in the nodules), upon which 
it doubtless preyed. As the skull is two feet long, and the 
whole head and body about nine feet, it must have far 
exceeded in size the largest lion or tiger, and probably that 
of any carnivorous land mammal that has ever lived. 

In North America these reptiles were also present in 
considerable abundance. Some, forming the sub-order 
Theriodontia, were allied to the Pariasauri, and were 
probably herbivorous ; while the Pariotrichidae were carni- 
vores, as were also a very distinct family, the Clepsydropidae. 
Of this latter group one genus, Dimetrodon, is here figured 
as restored by Sir Ray Lankester (Fig. 49). This is sup- 
posed to be allied to the living Hatteria of New Zealand. 
These strange carnivorous reptiles 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 













Fig. 48. — Skull of the gigantic Theriomorph 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.) 













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Fig. 49. — Probable Appearance of the Theriomorph Reptile 

Di.metrodon. 
rom the Permian of Texas. It was the size of a large dog. (From Sir Ray 
Lankester's Extinct Animals.) 




Fig. 50. — Skeleton of Ornithopodous Dinosaur {Iguanodon bernissartensis). 
From the Wealden of Belgium. Length, 30 feet along spine. (B. M. Guide.) 








<v. 



Fig. 51. — Probable Appearance of the Iguanodon. 
(From Sir Ray Lankester's Extinct Animals.) 



xi THE GEOLOGICAL RECORD 201 

owing to unfavourable circumstances the connecting links 
have rarely been preserved. The singular Chelonia (turtles 
and tortoises) appear 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 Carboni- 
ferous offered highly favourable conditions for the preserva- 
tion of the remains of such land animals had they existed. 
To bring about the modification 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 reptiles, must, with any reason- 
able speed of change, have required an enormous lapse of 
time, yet all these had their origin seemingly during the 
same period. Some account of the strange animals whose 
abundance and variety so especially characterised the 
Secondary period will now be given. 

Or d e r — Dinosau ria 

Some of the best known of these reptiles have been 
bund in our own country, and we will therefore begin with 
he Iguanodon, of which teeth and bones were found near 
aidstone (Kent) by Dr. Mantell in the early part of the 
Jast century, but no complete skeletons have been found, 
p. closely allied species from Belgium of the same age (the 
jWealden) is here figured (Fig. 50). It was about thirty 
r eet long, and is believed to have walked chiefly on its hind 
eet, and to have fed upon the foliage or fruits of good- 
iized trees. As shown in the restoration of the animal in 
ts supposed usual attitude when alive (Fig. 51), it would 
'.tand about fourteen feet high. The fore-limbs are com- 
batively small, terminating in a hand of five fingers, the 
humb being represented by a bony claw. The much longer 
lind legs, however, have feet with only three toes, much 
esembling those of running birds, and numerous impressions 
>f such feet have been found in rocks of the same age, hence 
he group to which it belongs has been named Ornithopoda 
r " bird-footed." From the character of these it seems 



202 



THE WORLD OF LIFE 



CHAP. 



probable that the animal would walk on all fours and leap 
with its hind legs in the manner of a kangaroo. 




Fig. 52. — Skull of Iquanodon bernissartensis. 
From the Wealden of Belgium. Three and a half feet long. (B.M. Guide.) 

The skull, as shown by Fig. 52, is three and a half feet 
long, and the numerous close-set serrated teeth seem well 




Fig. 53. — Skeleton of Armoured Dinosaur (Scelidosaurus karrisoni). 

From the Lower Lias of Charmouth, Dorset. Length along spine, about Ijj 

feet ; height as drawn, 7 feet. (B.M. Guide.) 



XI 



THE GEOLOGICAL RECORD 



203 



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 is named Stegosauria, " plated lizards," 
from their protective armour. The skeleton of one of 
these (Fig. 53) has long bony spines on the shoulders, 
which, if bearing a horny covering, would have been an 
effective protection against beasts of prey ; and this is 
followed by a row 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 enemy from the rear. 




Fig. 54. — Skull of Horned Dinosaur {Sterrolophus flakllatus). 
From the Upper Cretaceous of Wyoming, U.S.A. (B.M. Guide.) 

In another allied species, of which the skull is here 
shown (Fig. 54), there were two enormous horns above the 
eyes and a smaller one upon the nose ; while the margin 
of the bony expansion behind seems to have borne a row of 
spiny plates. 



204 THE WORLD OF LIFE 

As an illustration of how these huge but rather weak 
vegetable feeders were protected, the restoration of one of 
them as shown on the opposite page (Fig. 55), may be 
useful ; especially when we remember that the species 
figured was as bulky as a rhinoceros or elephant. It was 
found in the Upper Jurassic strata of North America. 

We now come to some of the largest land-animals 
which ever lived upon the earth — the Sauropoda, or lizard- 
footed Dinosaurs — and these were more or less amphibious. 
The skeleton of one of these, the Brontosaurus, is shown 
on page 205 (Fig. 56). It is said to have the smallest 
head in proportion to the body of any vertebrate 
animal. Professor 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 localities where the animals had 
evidently become mired." 

A creature nearly as large was the Cetiosanrus 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 American Atlantosaurus immanis, of which only 
fragmentary portions have been obtained ; but a complete 
thigh-bone, 6 feet 2 inches long, is the largest yet dis- 
covered. It was found in the Upper Jurassic strata of 
Colorado, U.S.A. 

The largest complete skeleton is that of the Diplodocus 
camegii, now well known to all who have recently visited 
the British Natural History Museum, where a model of it is 
mounted, as shown in the photograph of it here reproduced 
(Fig. 57) facing page 205. It is 80 feet in length, both 
neck and tail being enormously 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 must have lived 




Fig. 55. — 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.) 



XI 



THE GEOLOGICAL RECORD 



205 



chiefly in the water on juicy water-weeds, which its very weak 
teeth, as shown in the figure of the skull overleaf (Fig. 58) 
would alone have been such as it could graze on. The very 




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moderately deep water. The brain occupied the small 
space between and behind the eyes. 

These huge reptilian herbivora, feeding in marshes, lakes, 



206 



THE WORLD OF LIFE 



CHAP. 



or shallow seas, were preyed upon by the numerous 
crocodiles which lived throughout the same periods and 




Fig 58. — Skull of Sauropodous Dinosaur {Diplodocus). 
From the Upper Jurassic of Colorado, U.S.A. One-sixth nat. size. 

(B.M. Guide.) 

are everywhere found in the same strata. They were of 
varied forms and sizes, but as they did not differ much 




Fig. 59. — Skull of a Theropodous Dinosaur {Ceratosaurus nasicornis). 
From the Upper Jurassic of Colorado, U.S.A. One-sixth nat. size. 

(B.M. Guide.) 







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XI 



THE GEOLOGICAL RECORD 207 



in appearance from the various crocodiles and alligators 
now living in the tropics they need only be mentioned. 
But besides these there were true Dinosaurs of similar 
shape to the Iguanodon, but of rather less massive form 
and with strong teeth curved backward, which with their 
wide-opening jaws evidently adapted them to seize and 
prey upon the larger land-reptiles. These form the Sub- 
order Theropoda, or beast-footed Dinosaurs. The skull of one 
of these here shown (Fig. 59) is more than 2 feet long, but 
no complete skeleton has been yet discovered. The allied 
Megalosaurus was found by Dr. Buckland in the Wealden 
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 which 
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 
aften with a dilated swimming tail. They varied much in 
size, but were often very large. Plesiosaurus cramptoni, from 
the Upper Lias of Whitby, was 22 feet long, but some 
species from the Chalk formation were from 30 to 40 feet 
iong. A skull and jaws of P. grandis, from the Kimmeridge 
:lay, is 6 feet long, which, if the proportions were the same 
is those of the species here represented (Fig. 60), would 
iave belonged to an animal nearly 50 feet long. The 
whole group was extremely varied in form and structure, 
out all were adapted for preying upon such aquatic or 
marsh-frequenting animals as abounded during the same 
period. 

O r d e r — Ich tJiyopterygia 

All the members of the preceding order have the paddles 
supported by a complete bony foot or hand composed of 
ave separate fingers and connecting wrist-bones. But in the 
present 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 



208 



THE WORLD OF LIFE 



CHAP. 



B 



as shown in the drawings here reproduced (Fig. 62 A, B). 
They were also remarkable for their very large and highly 
organised eyes, which, with the lengthened jaws and closely 
set sharp teeth, indicate a perfect adaptation for capturing 
the fishes which the seas of that age no doubt produced in 

the same abundance and 
almost as great variety 
as our own. These crea- 
tures also varied much 
in size and shape, one 
from the Lower Lias of 
Warwickshire being 22 
feet long, but detached 
vertebras sometimes in- 
dicate a much larger 
size. In the older Tri- 
assic beds smaller species 
are found which were less 
completely aquatic ; and 
these seem to show 
an affinity to Amphibia 
rather than to reptiles, 
indicating that the two 
aquatic orders may have 
had independent origins. 
Still later, in the 
Cretaceous formation, 
there were other aquatic 
reptiles quite distinct 
from all the preceding, 
and more allied to our 
living lizards, having 
well - formed swimming 
feet, but snake-like or fish-like bodies. These serve to 
indicate how completely the reptiles of the Secondary epoch 
occupied the place now filled by the Mammalia, 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. 





o 00 



Fig. 62. 
Right Fore (A) and Hind (B) Paddles 

of Ichthyosaurus intermedws. 

From Lower Lias of Lyme Regis. One-third 

nat. size. (B.M. Guide.) 



I 



:i 



THE GEOLOGICAL RECORD 



209 



O rd er — Orn ithosau ria 

We come finally to one of the most remarkable develop- 
ments of reptilian life, the bird-lizards, more commonly 
;mown as Pterodactyls, which accompanied all the other 
trange forms of reptilian life in the Mesozoic period. They 



--•MU r- a &^s 




Fig. 63. — Skeleton of Pterodactylus spectabilis. 
f>m 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. 
1 (B.M. Guide.) 

ae first found a little later than the earliest Dinosaurs, in 
t.& Lower Lias of Bavaria ; but as they are, even then, 
fijly developed, though small, there must have been a long 
s ;ies of intermediate forms which probably reached back 
t'the Triassic if not to the Permian era. 

P 



210 



THE WORLD OF LIFE 



CHAP. 



The illustration of the skeleton of one of these early 
forms on the preceding page is of the natural size (Fig. 63). 
It 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. 




Fig. 64. — Restoration of a Long-Tailed Pterodactyl 

[Rhamphorhynchus phyllurus). 

From the Upper Jurassic of Bavaria. (B.M. Guide.) Expanse of wings mor 

than 2 feet. The long tail has a terminal web, shown in casts in fine lithe 

graphic stone. 

The above restoration (Fig. 64), shows a larger specie; 
from the Jurassic formation, at which period they were more 
varied. This had a very long tail with a dilated membram 
at its tip. Allied species, with a long pointed tail, have beei 
found in the Lias of Lyme Regis, and also at Whitby. 




■ica 



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^\ 



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 Pterodactj 
reached their greatest size, the species figured here havr 
an expanse of eighteen feet ; and these large forms have 
powerful but toothless beak (Fig. 65). 



XI 



THE GEOLOGICAL RECORD 211 



Fragments of bones from the English Chalk indicate an 
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 pro- 
jects a foot back from the head, and which Professor Marsh 
believes had a spread of wing 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 
entirely without teeth. There is an enormous occipital crest (c) projecting far 
behind the occiput, to which the muscles for flight were probably attached ; 
(a) the nares and pre-orbital cavity ; {b) 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 

.lass Reptilia, which had originated apparently during the 

ast stages of the Primary, became developed into many 

pecial types, adapted to the varied modes of life which 

he higher warm-blooded vertebrates have attained in our 

>wn time. The purely terrestrial type had their herbivora 

.nd carnivora corresponding to ours in structure and habits, 

tut surpassing them in size ; the amphibious or marsh 

pecies surpassed our largest existing crocodiles, while the 

rue aquatics almost exactly anticipated the form and habits of 

ur porpoises and smaller whales. The air, too, was peopled 

y the strange Pterodactyls which surpassed the bats in 

owers of flight, in which they almost rivalled the birds, 

'hile they exceeded both in the enormous size they attained. 

'onsidering how rare must have been the circumstances 

'hich led to the preservation in the rocks of these aerial 

reatures, we may conclude, from the large number of 

pecies known to us, that they must have been extremely 

aundant in middle and late Mesozoic times, and that 



212 THE WORLD OF LIFE chap. 

they occupied almost as important a place in nature 
as do the birds now. Yet not one of the varied forms 
either of the terrestrial Dinosaurs, the aerial Pterodactyls, 
or the aquatic Sauropterygia and Ichthyopterygia — all 
abounding down to Cretaceous times — ever survived the 
chasm that intervened between the latest Secondary and 
the earliest Tertiary deposits yet discovered. This is 
perhaps the most striking of all the great geological 
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 
appeared 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 
mammals 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 Phascolo- 
therium (Fig. 67). About forty years later a considerable 
number of similar remains — small mammalian jaws with 



t 



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I 







Jp 




Fig. 67. — Lower Jaw of Phascolotherium bucklakdi. 
From the Stonesfield Slate (Lower Jurassic), Oxfordshire. Outline fig. nat. size 

(B.M. Guide.) 







k 



Jttei 

Fig. 68. — Lower Jaw and Teeth of Spalacotherium tricuspidens. jlV 
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.M. Guide.) 




Fig. 69. — Lower Jaw of Triconodow mordax. 
Purbeck of Swanage. Nat. size. (B.M. Guide.) 



% 



5«no 



THE GEOLOGICAL RECORD 213 

teeth — were found in what is termed the dirt-bed at 
Swanage, in the upper part of the Jurassic formation. Two 
of these — Spalacotherium and Triconodon — are here repre- 
sented, and show how well they are preserved (Figs. 68 and 
69). 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 Wurtemberg. Both these types of jaw have 
been since found in considerable abundance in the Jurassic 
beds of Wyoming, U.S.A. These materials have enabled 
palaeontologists to decide that the former group were really 
l of the marsupial type, while the latter (and earlier in time) 
belong to a distinct sub-class, the Multituberculata, from 
the curiously tubercled teeth, resembling those of the 
Australian ornithorhynchus. Somewhat similar teeth and 
jaws have been found also in the Upper Cretaceous beds of 
North America. 

Now it is quite certain that these small mammals, so 
widely spread over the northern hemisphere, must have been 
developed through a series of earlier forms, thus extending 
back into that unknown gap between the Palaeozoic and 
Mesozoic eras, and being throughout contemporaneous with 
the great Age of Reptiles we have just been considering. 
Yet during the whole of this vast period they apparently 
never increased beyond 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 development for so long a period is 
altogether unexampled in the geological record. 

The Earliest Birds 

Birds present us with a similar problem, but in their 
case it is less extraordinary because their preservation is so 
much more rare an event, even in the Tertiary period, when 
we know they must have been abundant. The very earliest- 
known fossil bird is from the Upper Jurassic of Bavaria, and 
is beautifully preserved in the fine-grained beds of litho- 
graphic stone. The illustration on next page is from an 
exact drawing of this specimen (Fig. 70), in order to render 



214 



THE WORLD OF LIFE 



CHAP. 




Fig. 70. — Drawing of the Fossil Lizard-Tailed Bird 

(Archicopteryx macnira). 

From the lithographic stone beds of Bavaria (Upper Jurassic). About one-fourth 

nat. size. In the Nat. Hist. Museum. (B.M. Guide.) 



XI 



THE GEOLOGICAL RECORD 215 



more distinct the details very faintly shown in the original. 
To the anatomist every bone or fragment of a bone is recog- 
nisable ; while the unmistakable 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, notwith- 
standing 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 formation 
of Kansas, U.S.A., some 
well-preserved aquatic birds 
have been found. One is 
of large size (about 4 feet 
high), something like a 
diver, but with flat breast- 
bone, and therefore prob- 
ably with rudimentary 




much 



Fig. 71. — Skull of Archmopteryx 
siemens/, showing teeth. 



wings ; another, 
smaller, has long wing- 

, j 1 1 1 1 j From the lithographic stone (Upper Jurassic) 

bones and a deeply keeled of Bavaria . 6 fc at . size . original in the 

Sternum. The bony tail Berlin Museum. (B.M. Guide.) 

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 preserved. Those that 
died in or on the margins of rivers or lakes, or which fell 
into the water, would be at once devoured by the fishes or 
the aquatic or aerial reptiles which seem to have swarmed 
everywhere. 

Concluding Remarks on Mesozoic Life-Development 

The remarkable series of facts which have now been 
summarised, and which have been largely due to researches 
in North 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 sug- 
gested to account for the vast development of cryptogamous 
vegetation towards the close of the Palseozoic era The facts 



216 THE WORLD OF LIFE 

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 vertebrates were archaic forms of amphibians. 
Almost immediately after the deposit was completed true 
reptiles appeared all over the earth, and rapidly developed 
into that " Age of Reptiles " which is perhaps the greatest 
marvel of geological history. Birds and Mammalia also 
started into life, apparently branching 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 reptilian life totally dis- 
appeared, with the two exceptions of the crocodiles and 
the tortoises, which have continued to maintain themselves 
till our own day, while 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 
necessary preparation for them), plants underwent a similar 
transformation ; the prominent Cryptogams, Conifers, and 
Cycads of the Secondary era gave way towards its close to 
higher flowering plants, which thenceforth took the first 
place, and now form probably fully 99 per cent of the whole 
mass of vegetation, with a variety of nourishing products, in 
foliage, fruit, and flower, never before available. 

Now here we have a tremendous series of special 
developments of life-forms simultaneous in all parts of the 
earth, affecting both plants and animals, insects and verte- 
brates, whether living on land, in the water, or in the air, all 
contemporaneous in a general sense, and all determining the 
transition 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 oxygenated atmosphere, produced by the locking 
up of so much carbon in the great coal-fields of the world ; 



THE GEOLOGICAL RECORD 217 

so, I think, the next great advance was due to a continua- 
tion of the same process by a different agency. Geologists 
have often remarked on the progressive increase in the 
proportion of limestone in the later than in the earlier 
formations. In our own country we 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 North America. As lime- 
stone is generally a carbonate of lime, it locks up a consider- 
able 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 diminution 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 carbon- 
dioxide than at present, and that a continuous reduction of 
the amount has been going on, mainly through the extrac- 
tion 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 
appeared above the waters ; while its absorption by water 
was equally useful in rendering possible the growth of the 
calcareous 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 atmo- 
spheric 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 character- 
ised the three great geological areas ; but it does not seem 
sufficient to explain the very sudden and complete changes 



218 



THE WORLD OF LIFE 



CHAP. XI 



that occurred, and, more especially, the almost total ex- 
tinction 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 geologists, the 
Cainozoic. 










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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. Not only have the whole of the gigantic 
Dinosaurs and the accompanying swimming and flying 
reptiles totally disappeared, but they are replaced in every 
part of the world by Mammalia, which already exhibit 
indications of being the ancestors of hoofed animals, of 
Carnivora, and of Quadrumana. 

Order — Ungidata 

In the Lower Eocene strata of North America and 
Europe, the sub -order Condylarthra is well represented. 
These were primitive, five-toed, hoofed animals which, Dr. 
A. Smith Woodward tells us, " might serve well for the 
ancestors of all later Ungulata." One of these, Phenacodas 
pi'imczvus, was found in the Lower Eocene of Wyoming, 
U.S.A., and was about 4 feet long exclusive of the tail 
(see Fig. 72). Considering that this is one of the very 
earliest Tertiary mammals yet discovered, 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 modification into several of the 
chief types of the higher mammalia. So perfectly organised 
an animal could only have been one of a long series of forms 
bridging over the great gulf between it and the small rat- 
like mammals of the Mesozoic period. 

Another sub-order is the Amblypoda, of which the 
Coryphodon of Europe and North America is one of the 
best known. This was about 6 feet long, and was first 

219 



220 



THE WORLD OF LIFE 



CHAP. 



obtained from our London Clay. It had a heavy body, 
five -toed stumpy feet, and a complete set of 22 teeth 
in each jaw adapted for a vegetable diet ; but no defensive 
tusks or horns. Other allied species 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 lived upon the earth — the Dinocerata or 




FlG. 73. — UlNTATHERIUM INGENS. 
Eocene of Wyoming, U.S.A. One-thirtieth nat. size. (B.M. Guide.) 

" 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 sometimes protected by a bony flange pro- 
jecting downwards from the lower jaw immediately behind 
it, as well shown in the figure here given of Uintatherium 
ingens. This animal must have been about 1 1 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. The imperfect skull of 
another species (Fig. 74) shows even larger the bony horn- 
cores presenting all the appearance of having carried some 



XII 



LIFE OF TERTIARY PERIOD 221 



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 protective use. 
Figure 75 (on p. 222) represents the skeleton of one of 
the largest species without tusks. From the scale given, it 
must have been 11 or 12 feet long and nearly 8 feet high. 
Professor Marsh informs us that these strange-horned 




FlG. 74. — UlNTATHERWM CORNUTUM. 
From the Middle Eocene of Wyoming, U.S.A. (Nicholson's Palaeontology. ) 

animals have been found only 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 ancient 
tropical lake in which many of them were entombed. This lake- 
basin, now drained by the Green River, 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 
vertical thickness of more than a mile. ... At the present time 
this ancient lake-basin, now 6000 to 8000 feet above the sea, shows 



222 



THE WORLD OF LIFE 



CHAP. 



evidence of a vast erosion, and probably 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 



XII 



LIFE OF TERTIARY PERIOD 223 



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, 
Professor Marsh says : 

"The brain-cavity of Uintatherium is perhaps the most remark- 
able feature in this remarkable genus. It shows us that the brain 




Fig. 76. — Skull of Arsinoitherium zitteli. 
From the Upper Eocene of the Fayoum, Egypt. One-twelfth nat. size. 

(B.M. Guide.) 

was proportionately smaller than in any other known mammal, 
recent or fossil, and even less than in some reptiles. It is, in fact, 
the most reptilian brain in any known mammal. In U. mirabile 
(one of the large - tusked, horned species) it could apparently 
have been drawn through the neural canal of all the presacral 
vertebrae." 



224 THE WORLD OF LIFE 

An equally strange monster has been found in Egypt, 
and forms a new sub-order, Barypoda. It Is known from a 
very complete skull (Fig. 76, p. 223), 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 quantities of detached bones have also 
been obtained, sufficient to show that the creature was an 
ungulate of elephantine dimensions and altogether unique 
in appearance. 

Order — Carnivora 

These can also be traced back to middle or late Eocene 
times both in North America and Europe. They were 
moderate -sized animals, forming a distinct sub-order, 
Creodonta, the skeleton of one of which is shown in 
Fig. 77- They had flesh -eating teeth, but more like 
those of the carnivorous marsupials of Australia than of our 
living carnivores, with a type of skeleton showing consider- 
able lightness and activity. Some of the species were as 
large as lions. 

Some of the older remains in South America, called 
Sparassodonta, are believed to belong to the same or an 
allied sub-order. They occur in beds of Lower Miocene age 
in Patagonia ; and Mr. Lydekker holds them to be " un- 
doubtedly marsupials," allied to the Dasyuridae 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, Microbiotheridae, he also thinks were prob- 
ably " minute polyprodont marsupials of Australian type." x 

1 Geog. Hist, of Mammals, pp. 1 1 i-i 12. From these facts and others referred 
to in my preceding chapter, Mr. Lydekker thinks that "it is difficult to come to 
any other conclusion than that the ancestors of the Santa Crucian polyprotodont 
marsupials reached the country either by way of the Antarctic 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 diffi- 
culties in the way of such a theory in an Appendix to this chapter. The whole 
subject of the "Permanence of Oceanic and Continental Areas" is more fully 
discussed in my volumes on Darwinism and Island Life. 



XL 









XII 



LIFE OF TERTIARY PERIOD 225 



In the later (upper) beds of the Eocene formation and 
the Early or Middle Miocene, ancestral forms of many of our 




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[ammalia have been found both in Europe and North 

imerica ; but these are so numerous, and their affinities in 

iome cases so obscure, that only a few of the prominent 

examples need be given. One of these, whose skeleton is 

Q 



226 



THE WORLD OF LIFE 



CHAP. 



figured below (Fig. 78), belongs to the family Anthracotheridas, 



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which has affinities with the pigs and the hippopotami, of 
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Fig. 79. — Anoplotherium commune. 

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 for its 
continuous set of 44 teeth, there being no gap in the series. No living 
mammal except man has this characteristic. It is supposed to have been a 
highly specialised early type which has left no direct descendants. 







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Fig. 80. — Palmotherium magnum. 
From the Upper Eocene of Paris and the Isle of Wight. 

Palaeontology. ) 



(Nicholson's 



The numerous species of Palaeotherium were three-toed animals having resemblances 
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 considerably longer than here shown. 



j xn LIFE OF TERTIARY PERIOD 227 

I of this group are found in deposits of Middle Tertiary age 
all over the northern hemisphere. They have two, three, 

| or four separate toes, and teeth much like those of swine. 

Another family, the Anoplotheridse, contains a variety of 
animals which seem to be ancestral forms of the ruminants. 
The genus Anoplotherium (Fig. 79) was one of the most 
remarkable of these in having a full and continuous set of 

•■ teeth without any gaps, like that of the Arsinoitherium 
already figured. 

An allied family, Oreodontidee, somewhat nearer to 
ruminants, but with four-toed feet, were very abundant in 

1 North America in Miocene times. They were remotely 
allied to deer and camels, and were called by Dr. Leidy 

{; " ruminating hogs." They seem to have occupied the place 
of all these animals, six genera and over twenty species 
having been described, some of which survived till the early 
Pliocene. 

The family Palaeotheridee was also abundant during the 
same period in Europe, and less so in North 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 by Huxley's figures reproduced 
in my Darwinism. 

The Origin of Elephants 

Till quite recently one of the unsolved problems of 
palaeontology 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 North 
America ; one species, the mammoth, being found ice- 
preserved in Arctic Siberia in great quantities. Some of 
these were 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 



228 



THE WORLD OF LIFE 



CHAP. 



line of descent. But less than ten years ago a number of 
fossils were obtained by Dr. C. W. Andrews 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 primitive form now discovered was about the 
size of a very large dog, and its skull does not differ very 
strikingly from those of other primitive ungulates. It has, 
however, some slight peculiarities which show a connection 
with the Proboscidea. These are that the nasal opening is 
near the end of the snout, indicating, probably, the rudiment 
of a proboscis ; the back of the skull is also thickened 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 support the 
weight of the tusks 
and trunk. The 
teeth showtwo 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 distinguish the 
huge grinding teeth of the elephants. This creature was 
named MceritJicrium lyonsi ; and its remains have been found 
in great abundance along with those of both land and sea 
animals, showing that they were deposited in what was 
then the estuary of the Nile, though now far inland. 

Somewhat later, in the Upper Eocene, another group of 
animals, the Palaeomastodons, have been found, showing a 
considerable advance (see Diagram, Fig. 82). They vary in 
size from a little larger than the preceding to that of a small 
elephant. The skull is very much modified in the direction 




Fig. 81. — Skull of Mceritherium lyonsi. 

From the Middle Eocene of the Fayoum, Egypt 

One-seventh nat. size. (B.M. Guide.) 



- 



XII 



LIFE OF TERTIARY PERIOD 



229 



of some of the later forms. After these come the Tetra- 
belodons from the Miocene beds of France and North 



Recent 
Pleistocene 
Upper Pliocene 



ELEPHAS 
(short chinj 




Lower Pliocene TETRABELODON 

[longirostris stage] 
Upper Miocene (shortening chinj 




Middle Miocene TETRABELODON 

("ANGUSTIDENS STAGE] 
Lower Niocen e ( long chin) 



Upper Oligocene M W"t™nfrom Africa 

into Europe -Asia 




Lower Oligocene: 
UpperEocene 
Middle Eocene 
Lower Eocene 



PALAEOMASTODON 
(lengthening chin) 

MOERITHERIUM 
(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.) 



230 THE WORLD OF LIFE 

America, and the Pliocene of Germany. These were more like 
elephants in their general form, though their greatly elongated 
lower jaws, bearing incisor teeth, seem to be developing 
in another direction. In Tetrabelodon 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 Tetrabelodon angustidens (Fig. 83) shows 
the lower tusks shorter than the uppers, but in the specimen 
mounted in the Paris Museum, and photographed in Sir Ray 
Lankester's Extinct Animals, both are of the same length, 
and the upper pair curve slightly downwards on each side of 
the lower pair ; and they are thus shown in the suggested 
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 
sideways. It is most interesting to see how the difficulty 
was 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 
Mastodons, 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 
(which was originally classed as a Mastodon) ; and there 
are Indian extinct 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 farther, 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 



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Fig. 83. — Skeleton of Tetrabelodon angustidens. 
From the Middle Eocene of Sansaus, France. (B. M. Guide. 










■ § 



■ 



Fig. 84. — Probable Appearanxe of Tetrabelodon angustidens. 
(From Sir Ray Lankester's Extinct Animals.) 



Ion! 



XII 



LIFE OF TERTIARY PERIOD 231 



right direction. But here (owing probably to some excep- 
tionally 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 




Fig. 85. — Skeleton of Mastodon americanus. 
From the Pleistocene of Missouri, U.S.A. Length, 20 feet ; height, 9^ feet. 

(B.M. Guide.) 



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 generalised 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 
Mastodon has been found in the same deposits with stone 
arrow-heads, and was undoubtedly hunted by early man ; 



232 



THE WORLD OF LIFE 



CHAP. 



as was also the huge mammoth whose beautifully curved 
tusks form its chief distinction from the living Indian 
elephant (Fig. 86). This species is abundant in the 




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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 



xii LIFE OF TERTIARY PERIOD 233 

prehistoric man, either upon the tusks themselves or upon 
the flat portions of the horns of reindeer which he hunted 
for food. 

Tertiary Mammals of South America and Australia 

No part of the world has so many distinct groups of 
Mammalia peculiar to it as South America, among which the 
most remarkable are the sloths and the armadillos ; and all 
of them are found fossil in the middle or late Tertiary or 
the Pleistocene, from Brazil to Patagonia, and are often 
represented by strange forms of gigantic size. Some account 
of these will now be given. Darwin was one of the first 
collectors of these fossils on his voyage in the Beagle^ 
and during the last twenty or thirty years numerous 
travellers and residents, especially in Argentina, have more 
thoroughly explored the deposits of the pampas of various 
ages. Their great richness and importance may be indicated 
by the following enumeration of the chief orders of Mammalia 
represented in them. 

Of the Primates (or monkeys), all the remains are of 
the peculiar American families Cebidae and Hapalidae, with 
one extinct genus of the former. Bats (the order Chiroptera) 
are abundant, with several peculiar genera. The Insectivora 
are very rare in South America, but a fossil has been found 
supposed to belong to the peculiar West Indian family 
Solenodontidae. The Carnivora are chiefly represented by 
fossils of the American family Procyonidae (comprising the 
racoons and coati-mundis), of which several extinct genera 
have been obtained. The hoofed animals (Ungulata), which, 
from their 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 are altogether extinct. Among the former the 
most interesting are true horses of the genus Equus, as well 
as two peculiar genera of ancestral Equidae, distinct from 
those so abundant in North America. There are also 
several ancestral forms of the Llama tribe, one of which, 



234 THE WORLD OF LIFE 

Macrauchenia patachonica, was as large as a camel ; and 






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there are others so distinct as to form a separate family) 
Proterotheriidae. 



XII 



LIFE OF TERTIARY PERIOD 235 



Another sub - order, Astrapotheria, were more massive 
animals, some of which equalled the rhinoceros in size. They 
consist of two distinct genera, only found in the Patagonian 
deposits of Mid-Tertiary age. 1 

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 largest species of this sub-order is 
shown in Fig. Sy. 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 guinea-pig, 
are well represented among these fossils, and there are many 
extinct forms. Most of these are of moderate size, but one, 
Megamys, said to be allied to the viscachas, is far larger 
that any living rodent, about equalling an ox in size. 

Perhaps more remarkable than any of the preceding are 
the extinct Edentata 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 families, 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 Glyptodontidae and the 
Megatheriidae, the former being giant armadillos, the latter 
equally gigantic terrestrial 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 

A Geographical History of Mammals, R. Lydekker, F.R.S., etc., 1896, p. 81. 



CHAP. 



236 THE WORLD OF LIFE 

largest species occurred, the shell being often 6 or 8 feet 




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long. The skeleton of one of these is represented by Fig. 
88. One of the most recent (Dsedicurus) was 12 feet long, 




Fig. 89. — Probable Appearance of the Giant Ground-Sloth 

( Megatherium giganteuni). 

As large as an elephant. Found in the Pleistocene gravels of South America. 

(From Sir Ray Lankester's Extinct Animals, p. 172.) 




Fig. 90. — Mylodon robustus. 
From the Pleistocene of South America. (Nicholson's Paleontology. ) 






LIFE OF TERTIARY PERIOD 237 

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 few of them have 
been found in the Pliocene deposits of Texas. 

The extinct ground-sloths are even more remarkable, 
since 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 Megatherium, 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 enormous 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 power- 
ful 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 
survived till a very recent period and that they were contem- 
porary with man. Both human bones and stone implements 
have been found in such close association with the bones or 
skeletons 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. Bones 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 prob- 
ably ranged all over South America, and the two genera 
Megatherium and Mylodon occur also in the most recent 



238 



THE WORLD OF LIFE 



CHAP. 



deposits of the southern United States. The numerous 
skeletons in the pampas of Argentina are usually found on 




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the borders of old lakes and rivers, in the positions in \vhicl ; 
they died. They are supposed to have perished in the muc 
or quagmires while attempting to reach the water for drinl| 



XII 



LIFE OF TERTIARY PERIOD 239 



during dry seasons, great droughts being prevalent in the 
district ; but when these 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 
Naturalist's Voyage round the World (chap. v.). The skeleton 
and outline figure of a Mylodon shown in Fig. 90 was 1 1 
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 constituted the larger and more important portion 
of the mammalian 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 apparently 
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, however, are very productive in animal remains 
which are extremely interesting. 

They consist of many living species, but with them 



240 



THE WORLD OF LIFE 



CHAP. 



numbers of extinct forms, some of gigantic size, but all 
undoubtedly allied to those living in Australia to-day, 
Thus, bones of kangaroos are found ranging in size from 
that of the smallest living species up to that of a donkey, 
and sometimes of very distinct forms and proportions. But 




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.) 

with these have been found a huge wombat, the size of a large 
rhinoceros, of which the skull is here represented (Fig. 92). 
The complete skeleton 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. 




Fig. 93. — Skull of Thylacoleo carnifex. 
From the Pleistocene of Australia. One-fifth nat. size. (B.M. Guide.) 



! U 



\l 






LIFE OF TERTIARY PERIOD 241 

As it has been found in various parts of the continent, it was 
probably abundant. Another smaller animal of somewhat 
similar form was the Nototherium, which was found in Queens- 
land, together with the Diprotodon, about fifty years ago. 
A large phalanger was also found, which Professor Owen 
called the pouched lion {Thylacoleo carnifex), but it is doubtful 
whether it was carnivorous (see Fig. 93). True carnivorous 
marsupials allied to the " Tasmanian wolf" (Thylacinus) and 
the Tasmanian devil {Sarcophilus) are also found. 

How and when the marsupials first entered Australia 
has always been a puzzle to biologists, because the only non- 
Australian family, the opossums, are not closely allied to 
any of the Australian forms, and it is the opossums only 
which have been found in the European Early Tertiaries. 
But recent discoveries in South America have at length 
thrown some light on the question, since the Santa Cruz beds 
of Patagonia (Middle 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 Dasyuridae. There is also, in the 
same beds, another distinct family of small mammals — the 
Microbiotheridae of Dr. Ameghino — which, from a careful 
study of their dentition, are also considered by Mr. Lydekker 
to be " polyprotodont marsupials of an Australian type." l 

But even more important is the discovery of living 
marsupials 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 Ecuador. But in 1895 a larger species of the 
same genus was obtained from Bogota ; and it was then 
seen that they belonged 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 that 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 

1 A Geographical History of Mammals, p. 109. 

R 



242 



THE WORLD OF LIFE 



CHAP. 



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 Caenolestes, while their fossil allies are so 
numerous and varied that they have to be classed in three 
families — Abderitidae, Epanorthidae, 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 North 
America a similar phenomenon occurred. Two extinct lions ; 
a number of racoons and allied forms, including several 
extinct 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, 
and four genera of the wonderful terrestrial sloths, 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 
extraordinary ; 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), North 
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 
monkeys allied to South American forms ; numerous extinct 
Carnivora, including the great sabre-toothed tiger, Machaero- 



XII 



LIFE OF TERTIARY PERIOD 243 



dus ; several ancestral horses, including the European Anchi- 
therium ; several ancestral rhinoceroses, the huge horned 
Brontotheriidae, the Oreodontidae, 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 hemi- 
sphere 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 extraordinary is, that several of 
them were larger than any now living, while some were as 
gigantic as the huge ground-sloths and armadillos of the 
Pampas. There were numerous kangaroos, some much larger 
than any living, including species allied to the tree-kanga- 
roos of New Guinea ; a Phascolomys (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 
phalangers. Equally remarkable was the TJiylacoleo carnifex, 
nearly as large as a lion and with remarkable teeth (Fig. 93, 
p. 240). The very peculiar Nototherium, 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 New Zealand were of various 
sizes, but the largest was 8^- feet high when standing naturally, 
but when raising its body and neck to the fullest extent it 
would have perhaps reached to a height of 1 2 feet. 

In Madagascar also there was a huge bird, the /Epyornis, 



244 



THE WORLD OF LIFE 



CHAP. 



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 Pleistocene Mammalia 

The complete extinction of many of the largest Mam- 
malia, which were abundant in almost all parts of the world 
in Pleistocene times, has not yet received a wholly satis- 
factory 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 epoch, there has been very little modification of the 
earth's surface since the close of the Tertiary era ; and 
in several cases species which undoubtedly survived that 
event have since become extinct. This great climatic catas- 
trophe did undoubtedly produce 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 — Australia 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 
conditions, such as extension of land or water, climate, vege- 
tation, etc., which, combined with the special disabilities of 1 



XII 



LIFE OF TERTIARY PERIOD 245 



very large animals, are sufficient to account for the facts. 
It may be well here to state again the causes which lead 
to the extinction of large 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 important, 
perhaps, is the fact that very large animals always increase slowly 
as compared with small ones — the elephant producing a single young 
one every three years, while a rabbit may have a litter of seven 
or eight young two or three times a year. Now the probability of 
useful variations will be in direct proportion to the population 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 
are 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 
with the remains of such ambitious offshoots, many 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 evolution, 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 hog- 
family (Suidae), than it is in America, under the closely 
allied peccary type (Dicotylidae). 



246 THE WORLD OF LIFE chap. 

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 during a period of such limited duration as is the 
Pleistocene (or Quaternary) age, and under conditions which 
were certainly not very different from those under which 
they had been developed and had lived in many cases down 
to the historical period. 

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. 
When 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- 4- l %)> 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 body 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 
which at the culmination 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 sufficient explanation of the phenomena is, I 
think, due to two circumstances. Ever since the fact of the 
antiquity of man was 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 






LIFE OF TERTIARY PERIOD 247 

Boucher de Perthes in the gravels near Amiens. It has 
been thought necessary to minimise each fresh item of 
evidence, or in many cases to reject it altogether, on the 
plea of imperfect observation. Thus the full weight of the 
ever-accumulating facts has never been adequately recog- 
nised, because each new writer has been 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 evolu- 
tion) 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 North America (in my Natural Selec- 
tion and Tropical Nature) I have given numerous examples 
of both these states of mind. And what makes them so 
specially unreasonable is, that all evolutionists are satisfied 
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 Pleisto- 
cene period, but that they are not also found throughout 
the Pliocene, and also in some Miocene deposits. There is 
not, as often assumed, 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 
extinct Pleistocene Mammalia are sufficiently clear, while 
that the Australians are equally ancient is proved by their 
forming so well-marked and unique a race, the fact that 
man should everywhere have helped to exterminate the 
various huge quadrupeds, whose flesh would be a highly- 
valued food, almost becomes a certainty. The following 
passage from one of our best authorities, Mr. R. Lydekker, 
F.R.S., puts the whole case in a very clear light, though 
he does not definitely accept the conclusion which I hold 
to be now well established. He says : 



248 



THE WORLD OF LIFE 



CHAP. 



" From the northern half of the Old World have disappeared the 
mammoth, the elasmothere (a very peculiar, huge rhinoceros, whose 
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 glypto- 
donts, 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 
European mastodons and the southern elephant (Elephas meridion- 
alis) 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 
northern 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." l 

It is sometimes thought that early man, with only the 
rudest weapons, would be powerless against large and often 
well-armed mammals. But this, I think, is quite a mistake. 
No weapon is more effective for this purpose than the spear, 
of various kinds, when large numbers of hunters attack a 
single animal ; and when made of tough wood, with the 
point hardened by fire and well sharpened, it is as effective 

1 Lydekker's Geographical History of Mammals, p. iS. 



LIFE OF TERTIARY PERIOD 249 

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 Malay 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 
combination would have rendered him fully able to kill or 
capture 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, 
especially 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 serving to explain, 
if only partially, the successive dying out of numbers of 
large animals involving a complete change in the pre- 
ponderant types of organic life at certain epochs ; and to 
this question and some others allied to it a separate chapter 
must be devoted. 

APPENDIX 

THE THEORY OF CONTINENTAL EXTENSIONS 

Most writers consider that the facts given on p. 224 go to prove 
the existence of a direct land-connection between South America 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 



250 THE WORLD OF LIFE chap. 

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 4 
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 
numerous than the marsupials ; they were more varied in structure 
and mode of life; and it is almost incredible that not one; 
representative of these somewhat higher forms should 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 J 
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 
numerous 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 thei 
ocean ; that it should have become sufficiently stocked with life tc| 
serve as a bridge (7000 miles long!), and that a few very smal: 
marsupials only should have crossed it ; that it then sank asj 
rapidly as it had been formed ; with the one result of stocking 
Australia with marsupials, while its other forms of life — plants, birds j; 
insects, molluscs — show an unmistakable derivation from the If 
Asiatic continent and islands. A careful examination of a large! 
globe or South Polar map, with a consideration of the diagram of thel 
proportionate height of land and depth of ocean at p. 345 of m; ; 
Darwinism, together with the argument founded upon it, will 
I think, convince my readers that difficulties in geographical! 
distribution cannot be satisfactorily explained by such wildly 
improbable hypotheses. If the facts are carefully examined, it wilj 
be found, as I have shown for the supposed " Atlantis " an< 
" Lemuria," that such hypothetical changes of sea and land alway 
create more serious difficulties than those which they are suppose^ 
to explain. People never seem to consider what such an explans 
tion really means. They never follow out in imagination, step b 



' 



LIFE OF TERTIARY PERIOD 251 

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 iooo miles farther than from Southampton 
to the Cape. This alone should surely give us pause. But 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 New 
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 change of 
climate in Mid-Tertiary times as would be required to render such 
a route possible. But the mere physical difficulties 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 movements appear to be slow creeping undulations passing 
over continental plateaux and their immediately adjacent sub- 
marine extensions. Sometimes the depressions seem to have taken 
the form of basins ; but we cannot conceive of any elevation 
of continental dimensions, or depression of oceanic character as 
to depth and area, without the complementary movement to 
complete the undulation. 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 
adduced 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 
interchanges 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 
forth, it has been subject to more than the usual amount of 
objection 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 
difficulties to the acceptance of natural selection as a sufficient 
explanation 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 
following : — 

i. 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 
importance. The first is, in my opinion, wholly speculative 
and of no value, inasmuch as it applies to what happened in 
the earlier stages of evolution, of which we have a minimum 
of knowledge. The second is of somewhat more importance ; 
for, though in the great majority of cases of adaptation the 
ordinary well-known facts of variation and survival would 

252 



ch.xiii EXTENSIONS OF DARWINISM 253 

amply suffice, yet there are conceivable cases in which 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, 
endeavour to explain in as simple a manner as possible how 
these three objections have been overcome. 

( I ) 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, which will apply not only to certain 
individual cases, but to all. The most general and therefore 
the best answer 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 
beginning further and further back, and find that a single origin 
accounts 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, 
for burrowing, for swimming, or for flying, and that their 
first appearance goes back to Palaeozoic times in the paired 
fins of early fishes, while their actual origin must have been 
much farther back, in creatures whose skeleton was not 
sufficiently solidified to be preserved. 



254 THE AVORLD OF LIFE 



CHAP. 



There is, however, a more general explanation even than 
this, and one that applies to what has always been held to 
be the most difficult of all — that of the origin of the organs 
of sense. 

The various sensations by which we 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 papillae of the tongue ; and we see by the impact 
of ether-vibrations on the retina ; and as other ether-vibra- 
tions 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 fundamentally connected if not identical, 
seems not unreasonable. 

Now, 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 organisation, so have special parts of their bodies become 
adapted to receive, and their nervous system to respond to, 
the various contacts with the outer world which produce 
what we term sensations. There is therefore, probably, no 
point in the whole enormous length of the chain of being, 
from ourselves back to the simple one-celled Amoeba, in which 
the rudiments of our five senses did not exist, although no 
separate organs may be detected. Just as its whole body 
serves alternately as outside or inside, as skin or as stomach, 
as limbs or as lips, so may every part of it receive a slightly 
different sensation from a touch outside or a touch inside,; 
from an air-vibration or from an ether-vibration, from those 
emanations which affect 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 



xin EXTENSIONS OF DARWINISM 255 

marvellous substance, protoplasm, and they were rendered 
possible when that substance was endowed with the mysterious 
organising 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, numerous 
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 under 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 
modifications of its external covering are needed. Hence 
the infinite variety in nature — a variety which, were it not so 
familiar, would be beyond the wildest flights of imagination 
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 
unsupported by what is known of the progressive develop- 
ment of all structures through slight modification of those 
which preceded them. The objection as to the beginnings 
of new organs is a purely imaginary one, which entirely falls 
to pieces in view of the whole 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. 



256 



THE WORLD OF LIFE 



CHAP. f 



(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 different parts of the body, and these, it is said, cannot be 
left to chance. Herbert Spencer discussed this point at 
great length in his Factors of Organic Evolution ; and, as 
one of the illustrative cases, he takes the giraffe, whose 
enormously long neck and forelegs, he thinks, would have 
required so many concurrent variations that we cannot 
suppose them to have occurred through ordinary variation. 
He therefore argues that the inherited effects of use and 
disuse are the only causes which could have brought it 
about ; and Darwin himself appears to have thought that 
such inheritance did actually occur. 

The points which Spencer mainly dwells upon are as 
follows : 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 forelegs 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 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 forelegs 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 require modifications exactly adapted to 
the change in the other parts ; and he urges that any in- 
dividuals in which all these necessary variations did not take 
place simultaneously, would be at a disadvantage and would 
not survive. To do his argument 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 carrying on the nutrition of the two. The entire 



xiii EXTENSIONS OF DARWINISM 257 

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." 

Now, 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 
small. But I have shown in the early chapters of this book 
(and much more fully in my Darwinism) that all these 
assumptions 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 halves 
— those which possess the special quality required above or 
below the average — it may be said that 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 
individuals are compared ; but nature deals with thousands 
and millions 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 

S 



258 THE WORLD OF LIFE 

structures, would be considerably modified in a hundred or 
a thousand generations, and we have no absolute know- 
ledge that any great change would be required in less time 
than this. 1 

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 which 
have occurred during the thousands or millions of years of 
its existence as a species. This implies that, for all ordinary 
conditions and all such adverse changes as occur but once in 
a century or 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 millions, 
which they were 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 
effected in a thousand or even a million of centuries. This 
happened because the changes were different in kind, as well 

1 A 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 response of all the muscles concerned in the 
operations each has to perform. If all the special variations required to produce 
such individuals were set 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. 
Yet they certainly do so arise. And just as cricketers are chosen, not by ex- .' 
temal 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 
creature lives. The species thus becomes adapted, first to 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. 




EXTENSIONS OF DARWINISM 259 

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 
dominant species to a normally 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 existence 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 Car- 
nivora into another continent or extensive area (as appears 
to have occurred with Africa in Tertiary times), in which 
case it is quite possible that such an animal as the American 
bison might have been first reduced in numbers, and, for 
want of any sufficiently 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 principle 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 
explained, to a degree which might sometimes make all the 
difference between life and death to a certain number of 
species. It depends upon the well-known fact that the use 
of any limb or organ strengthens 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 in- 
creased powers of running, or jumping, or tree-climbing, or 
swimming, then, during the process of eliminating those 
individuals who were the worst in these respects, 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 considerable number would 
become capable of surviving, year after year, to a normal 
old age, and during this whole period would, year by year, 



260 THE WORLD OF LIFE chap. 

have fresh descendants, and of these only the very best, the 
most gifted naturally, would survive. The increased adapta- 
tion during the life of the individual would not be trans- 
mitted, but the quality of being improvable during life would 
be transmitted, and thus additional time and a considerably 
increased population would give more materials for natural 
selection to act upon. With this help the species 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 under 
the new conditions. 1 

Now, while it must be admitted, that under certain 
conditions, 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 mimicry of protected groups. Here the use 
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 

1 As many readers are ignorant of the extreme adaptability of many parts of i 
the body, not only during an individual life, but in a much shorter period, I will ; «;e 
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, j 
Suddenly the man sprang up and struck a violent blow at the doctor's neck with 
a large sharpened nail, and almost completely severed the carotid artery. The \ 
warder seized the man, the assistant gave the alarm, while my friend sat down j . . 
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 i •<'. 
applied proper pressure, 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 speaking he was quite as wellj 
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. 256. 



xiii EXTENSIONS OF DARWINISM 261 

of the teeth, which are wonderfully varied throughout the 
whole of the vertebrate sub-kingdom. Yet the more or less 
use of the teeth cannot be shown to have any tendency to 
change their form 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 mammals, have never been shown to have 
their special textures, shapes, 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. Neither 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 Selection, an Important Extension 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 develop- 
ment of ornamental colour or appendages in the males, yet, 
when he had adduced 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 
effects imputed to it so amazingly improbable, that I felt 
certain that some other cause was at work. In 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 plumes of 
the males were not in themselves attractive, but served 
merely as signs of sexual maturity and vigour. In the case 
of insects, especially in butterflies, where the phenomena of 
colour, and to some 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, 



262 THE WORLD OF LIFE 

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 breeding 
season." 1 

Now the idea here suggested, of all these strange and 
beautiful developments of plumage, of ornaments, or o 
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 have most offspring who were equally 
or even more highly gifted ; and thus there would arise al 
continually increasing vitality which would be partly ex- 
pended in the further development of those ornaments and 
plumes which are its result and outward manifestation 
The varying conditions of existence would determine the 
particular part of the body at which such accessory orna 

1 Natural Selection and Tropical Nature (new ed., 1895), pp. 391-392 
For full details see Darwinism, chap. x. (1901). 



I 



IB 



EXTENSIONS OF DARWINISM 263 

ments might arise, usually, no doubt, directed by utility to 
the species. Thus the glorious train of the peacock might 
have begun in mere density of plumage covering a vital 
part and one specially subject to attack by birds 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 lower branches of 
large trees. In the Argus -pheasant it is the secondary 
wing-feathers that are exceedingly long and broad, so as to 
be almost as much a hindrance to strong or rapid flight as 
is the train of the peacock ; and in both birds these orna- 
mental plumes have evidently reached the utmost dimensions 
compatible with the safety of the species. 

There can also be little doubt that in many of the birds- 
of-paradise and of the humming-birds, in the enormous crest 
of the umbrella-bird, in the huge beaks of the hornbills and 
the toucans, in the lengthy neck and legs of the flamingos 
and the herons, these various ornamental or useful append- 
ages have reached or even overpassed the maximum of 
utility. In another class of animals we have the same 
phenomenon. The expansion of the wings in butterflies 
and moths reaches a maximum in several distinct families — 
the Papilionidse, the Morphidae,the Bombyces, and theNoctuae, 
in all of which it 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 overpassed the line of permanent safety, and under 
the first adverse conditions have led to extinction. Both 



264 THE WORLD OF LIFE chap. 

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 apparently 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 developed 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 dimen- 
sions ever reached by a flying creature, and then the whole 
group became extinct at a time when a higher type, the 
birds, were rapidly developing. 

With mammals the case is even more striking, all the 
earliest forms of the Secondary age being quite small ; while 
in the Tertiary period they began to increase in size and to 
develop 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 extinct. Others of a lower and more generalised : 
type, but equally bulky, had successively disappeared at the 
termination 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 ; the latter passing from a 
hornless state to one of simple horns, gradually increasing in 
size and complexity of branching, till they culminated in the 
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 phenomenon in his presi-, ^ 
dential address to the Geological Section of the British 
Association 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 
emphasised by Darwin), that the higher form of one group 
never developed from similar forms of a preceding lowei 



:• 



EXTENSIONS OF DARWINISM 265 

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 
discussing : 

" Still more significant, however, is the discovery, that towards 
the end of their career through geological time, totally different 
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 period, 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 extinct. 

" Another frequent mark of old age in races was first discussed 
and clearly pointed out by Professor C. E. Beecher 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 as 
soon as the race they represent has reached its prime and begins to be 
on the down grade. Among familiar instances may be mentioned 
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 continual 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 acquired 
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. The 
excessive enlargement of the upper canine teeth in the sabre-toothed 
tigers (Machserodus and its allies) must also eventually have hindered 
rather than aided the capture and eating of prey." x 

1 The species Macharodus neogceus, the skull of which is shewn in Fig. 94, 
appears to have had the largest canines of any species of the genus ; and we are 



266 THE WORLD OF LIFE chap. 

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 survived 
only those members of the group in which the attenuated mandibles 
became shortened, leaving the modified face to act as a proboscis. 
The elephants thus arose as a kind of afterthought from a group of 
quadrupeds that were rapidly approaching their doom." (See 
figures in last chapter, p. 229.) 

This last is a specially interesting case, because it is the 
only one in which, without change of general environment, 
or apparently of habits, a highly developed animal has 
retraced its latest steps, and then advanced in a new line 
of development, leading to the wonderful trunk and the 
enormous tusks of the modern elephant, as explained in 
Chapter XII. That these have now attained the maximum 
of useful growth is indicated by the fact that among the 
extinct forms are those in which they are developed to an 
unwieldy size, as in Elephas ganesa of North-West India, 
whose slightly curved tusks, sometimes 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 Palaeozoic rocks, in 
their last stages " developed strange knobs and spikes on 
their shells, so that they seemed to be trying experiments in 
excessive variation." 

told by Messrs. Nicholson and Lydekker (Manual of Paleontology, 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. 







Fig. 94. — Machmrodus neogmus (Sabre-Toothed Tiger). 
From the Pleistocene of Buenos Ayres. One-eighth nat. size. (Nicholson's 

Palaeontology. ) 




Fig. 95.— Skeleton of Giant Deer [Cervus giganfeus). (B.M. Guide.) 

From a peat-bog in Ireland. One-thirtieth nat. size. 

The antlers were often 9 feet across from tip to tip, sometimes 1 1 feet. 



IB 



!»0 

it 

■■:; 

tali 

sin 

L 



XIII 



EXTENSIONS OF DARWINISM 267 



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. 





Fig. 96. — Coxocoryphe sultzeri. 
Upper Cambrian. 



Fig. 97. — Paradoxides bohemicus. 
Upper Cambrian. 



Eccentric forms of Ammonites 

At a later period the won- 
derfully rich and varied Ammo- 
nites show still more curious 
changes. Beginning in the 
Devonian formation they in- 
creased in variety of form and 
structure all through the succeed- 
ing formations, till they finally 
died out in the Cretaceous. The 
two species figured overleaf from 
the Trias (Figs. 99, 100) may be 
taken as typical ; but the varia- 
tions in surface pattern are almost 
infinite. Visitors to Weymouth 
or Lyme Regis may find such in 
abundance under Lias cliffs, or 
in the former place along the shores of the backwater. 

As time went on Ammonites increased in size, till in 
the Chalk formation specimens two or three feet diameter are 




Fig. 98. — Acwaspis dufreskoyi. 
Silurian (Bohemia). 



268 



THE WORLD OF LIFE 



CHAP. 



not uncommon. One of the largest English specimens in 
the British Museum (Natural History) was found at Rotting- 
dean, near Brighton, and is 3 feet 8 inches across ; but the 








Fig. 99. — Ceratites nodosus. Trias. Fig. 100. — Trachyceras aon. Trias. 

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 





Fig. i ox. — Crioceras emerici. 
Cretaceous. 



Fig. 102. — Heteroceras emerici. 
Cretaceous. 



were straight, and gradually became closely coiled. This 
form was maintained almost constant throughout the vast 
periods of the Mesozoic age, till towards the 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 (Fig. 



1 



ts 




XIII 



EXTENSIONS OF DARWINISM 269 



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. 103. — Macroscaphites ivanii. Cretaceous. 




Fig. 104. — Hamites rotundus. Cretaceous. 




Fig. 105. — Ptychoceras emericianum. Cretaceous. 





Fig. 106. — Ancyloceras matheronianum. Gault. 
Late Ammonites. (From Nicholson's Palaeontology.) 

shapes, in the last throes of dissolution." These strange 
forms (Figs. 96-106) are reproduced from Nicholson's 
Palaeontology, and there are many others. 



270 THE WORLD OF LIFE chap. 

Special Features in the Development of Vertebj'ates 

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 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 mammals, the Creodonta and Sparas- 
sodonta of the Early Tertiaries both of the eastern and 
western hemispheres. These were sometimes as large as 
lions or bears, and had equally well developed canine teeth, 
but very small brains ; and they all died out in Eocene or 
Early Miocene times, giving way to small ancestral 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 of 
incisors 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 — which 
is stored up in the paunch for rumination when at rest ; 
and the absence 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 by 
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 
destructive as the smaller members of the cat-tribe. This 
partial or total disappearance of the teeth has no doubt been 
helped on by the same principle which led to the persistent 
increase of useless appendages till checked by natural selec- 
tion or till it led to the extinction of the entire race. 






EXTENSIONS OF DARWINISM 271 

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 
explaining 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 
discoveries have been made in what may be termed the 
mechanism of growth and reproduction ; each successive 
advance in microscopic power and methods of observation 
have brought to light whole worlds of complex structure 
and purposive transformations in what 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 necessary to show briefly how 
Weismann's new theory helps us to understand the facts of 
Hfe-development we have been dealing with. For this 
purpose I cannot do better than quote Professor Lloyd 
Morgan's very clear statement of the theory. He says : 1 

"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 dwindle 
and eventually disappear. The suggestion is interesting, but one 
wellnigh impossible to test by observation. If accepted as a factor, 
it would serve to account for the inordinate growth of certain 
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 
1 Habit and Instinct, p. 310. 



272 THE WORLD OF LIFE 



CHAP. 



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, they 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.' " 1 

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 
reappear at the same place for several generations ; it is difficult to 
interpret such facts of particulate inheritance except on the theory 
that the germ-plasm is built up of a large number of different 
determinants. 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 
thoroughly acquainted, not only with all Weismann's works, I 
having himself translated some of them, but also with the \ 
work of other European and American writers on this very 
difficult problem ; 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 wonderfully 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 

1 The Evolution Theory, 1904, vol. i. p. 355. 



EXTENSIONS OF DARWINISM 273 

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 increasing, 
generation after generation, by the survival of more and 
more vigorous determinants. 

There is therefore both an internal and an external 
struggle for existence affecting all the special parts — organs, 
ornaments, etc. — of every living thing. With regard to the 
more important structures, such as the limbs, the organs of 
vision and hearing, the teeth, stomach, heart, lungs, etc., on 
which 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 
determinants to increase the growth and vigour of its special 
determinates, by elimination of the individuals which exhibit 
such unbalanced growth. But in the case of appendages, 
ornaments, or brilliant colours, which may begin as a mere 
outlet 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 will not be the same danger to the very existence of 
the adult animal. It will, however, often happen that the 
increase through germinal selection will continue beyond 
the point of absolute utility to the individual ; between 
which and the point of effective hurtfulness there may be a 
considerable margin. In this way we have a quite intelligible 
explanation of the enormous development of feathers or 
decorative plumes in so many birds, enormous horns in deer 
and antelopes, huge tusks in elephants, and huge canine 
teeth in other quadrupeds. This 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 abundant, 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 
:>f some useless organs, which mere disuse is hardly sufficient 

T 



274 THE WORLD OF LIFE chap. 

to explain ; such are the lost hind limbs of whales, the , 
rudimentary wings of the Apteryx, the toothless beak of I 
birds, etc. 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 determinants to be crowded out by the competition i 
of those of adjacent parts, the increased development of i 
which was advantageous. 

By this very ingenious, but, though speculative, highly 
probable hypothesis, extending the sphere of competition for 
nourishment and survival of the fittest from the organism as; 
a whole to some of its elementary vital units, Professor 
Weismann has, I think, overcome the one real difficulty in the 
interpretation of the external forms of living things, in all their 
marvellous details, in terms of normal variation and survival 
of the fittest. We have here that " mysterious impetus " to 
increase beyond the useful limit which Dr. Woodward has 
referred to in his address already quoted, and which is alsc 
a cause of the extinction of species to which Mr. Lydekkei 
referred us, as quoted towards the end of the preceding chapter 

Illustrative Cases of Extreme Development 

Two examples of this extreme development have not 
I think, yet been noticed in this connection. The wonderfu 
long and perfectly straight spirally twisted tusk of tfr 
strange Cetaceous mammal, the narwhal, is formed by ai 
extreme development, in the male only, of one of a pair c 
teeth in the upper jaw. All other teeth are rudimentary, a, . c 
is the right tooth of the pair of which the left forms tb 
tusk, often 7 or 8 feet long, and formed of a very fidwft: 
heavy ivory. The use of this is completely unknown, fc 
though two males have been seen playing together, apparently 
with their tusks, they do not fight, and their food, being sma 
Crustacea and other marine animals, can have no relatic 
to this weapon. We may, however, suppose that the tu< 
was originally developed as a defence against some enem 
when the narwhal itself was smaller, and had a wider ran£ 
beyond the Arctic seas which it now inhabits ; and wh< 
the enemy had become extinct this strange weapon went « 






EXTENSIONS OF DARWINISM 275 

increasing through the law of germinal selection, and has 
thus become useless to the existing animal. 

The other case is that of the equally remarkable 
Babirusa of the islands of Celebes and Buru, 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 having been long isolated in a 




Fig. 107. — Head of Babirusa (Babirusa aljurus). 
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 
piercing the skin of the face, resemble horns rather than teeth, and curve 
backwards and downwards. (Flower, Study of Mammals.) 

country where there were no enemies of importance, 
natural selection ceased to preserve them 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 individuals 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 
variety of form, that strange luxuriance of outgrowths, and 
that exquisite beauty of marking and brilliancy of colour, 



276 THE WORLD OF LIFE chap. 

that render 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 Batchian I obtained a bird in which 
from the bend of the wing (corresponding to our wrist) there 
spring two slender and flexible white feathers on each side! 
standing out from the wing during flight, whence it has 
been termed the standard-winged bird-of-paradise. Again. 
a few years ago, there was discovered in the mountains ol 
German New Guinea another quite new type, in which 
from the corner of each eye, a long plume arises more thar 
twice the length of the bird's body, and having, on one side 
only of the midrib, a series of leaf-shaped thin horny plate.' 
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-paradisi, 
now known, we have a series of strange ornamental plume, 
which in their shape, their size, their colours, and their poinj 
of origin on the bird, exhibit more variety than is found i; 
any other family of birds, or perhaps in all other know:; 
birds ; and' we can now better explain this by the assistanc 
of Weismann's law in a highly dominant group inhabiting 
a region which is strikingly deficient in animals which ar 
inimical to bird-life in a densely forest-clad country. 

To this same principle we must, I think, impute the 
superfluity of dazzling colour in many birds, but more espec 
ally in many insects, in which it so often seems to go f< 
beyond usefulness for purposes of recognition, or as a warnin, 
or a distracting dazzle to an attacking enemy. 

Even in the vegetable kingdom this same law may ha^; 
acted in the production of enormous masses of flowers or 
fruits, far beyond the needful purpose of perpetuating tl 



XIII 



EXTENSIONS OF DARWINISM 277 



species ; and probably also of those examples of excessive 
brilliancy 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 vegetable world. 

We may also owe to it the superabundant production of 
sap which enabled the early colonists of America to make 
almost unlimited 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 will yield this quantity for forty years without being 
at all injured ; and large quantities of such sugar are still 
made for home consumption, the molasses produced from it 
being said to be superior in flavour to that from the sugar- 
cane. Here surely is a very remarkable case of an excessive 
surplus product which is of great use to man, and, so far as 
we can see, to man only. The same phenomenon of a 
surplus product is presented by the Para rubber - trees 
(Siphonia, many species), from which, at the proper season, 
large quantities of the precious sap can be withdrawn annu- 
ally for very long periods, without injuring the trees or 
producing a diminution of the supply. There are also many 
other useful vegetable products, among those referred to in 
our fifteenth chapter, to which the same remark will apply ; 
and it seems probable 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 well 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 



278 THE WORLD OF LIFE chap. 

ultimate purpose is (so far as we can discern) the develop- 
ment of mankind for an enduring spiritual existence. With 
this object in view it would be important to supply all 
possible aids that a material world can give for the training 
and education of man's higher intellectual, moral, and aesthetic 
nature. If this view is the true one, we may look upon our 
Universe, in all its parts and during its whole existence, as 
slowly but surely marching onwards to a predestined end ; 
and this involves the further conception, that now that man 
has been developed, that he is in full possession of this earth, 
and that upon his proper use of it his adequate preparation 
for the future life depends, then 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. 

All 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 calcu- 
lated to bring about this result. And if the best for its 
special purpose, 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 contemporaries 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 endeavoured to learn the lesson they are intended 
to teach us, we 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 own 
uses, as indicating a development for the service of man. 
This variety and beauty, even the strangeness, the ugliness, 
and the unexpectedness we find everywhere in nature, are, and 
therefore were intended to be, an important factor in our 
mental development ; for they excite in us admiration 
wonder, and curiosity — the three emotions which stimulate 






xiii EXTENSIONS OF DARWINISM 279 

first our attention, then our determination to learn the how 
and the why, which are the basis of observation and experi- 
ment and therefore 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 defaced. To pollute a spring or a 
river, to exterminate a bird 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 they 
so loudly and persistently prate and preach. 

Yet during the past century, which has seen those great 
advances in the knowledge of Nature of which we are so 
proud, there has been no corresponding development of a 
love or reverence 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 manufactories and of cities ; and this has been done 
by all the greatest nations claiming the first place for civili- 
sation and religion ! And what is worse, the greater part of 
this waste and devastation 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 almost every case easily preventable. 
Yet they are not prevented, solely because to do so would 
somewhat diminish the profits of the capitalists and legis- 
lators who are directly responsible for this almost world-wide 



280 THE WORLD OF LIFE 

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 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 employers ; that no one shall be allowed to 
accumulate wealth by the labour of others unless and until 
every labourer shall have received 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 community. 

The Teachi7ig of the Geological Record 

But this is a digression. Let us now return to a 
consideration of the main features of the course of life- 
development. 

The first point to which 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 great 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 Amphibia 






EXTENSIONS OF DARWINISM 281 

and archaic reptiles. There were, however, a considerable 
number of primitive centipedes, spiders, Crustacea, and 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 
developed ; and this was 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 different 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 low 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 
everywhere subject to the attacks of large plant-devouring 
reptiles, and under this new environment it must necessarily 
have started on new lines of evolution tending towards those 
higher flowering plants which, throughout the Tertiary 
period, became the dominant type of vegetation. It seems 
probable that throughout the ages animal and vegetable 
life acted and reacted on each other. The earliest luxuriant 
land-vegetation, that which formed the great coal-fields of 
the earth, was probably adapted to the physical environ- 
ment 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 vegetation and to survive in the heavy 
carbonated atmosphere. This in turn became more varied and 



282 THE WORLD OF LIFE chap. 

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 Carnivora 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 directions, occupy- 
ing the many places in nature left vacant by these animals, 
and thus initiated that wonderfully varied mammalian life 
which throughout the whole Tertiary period occupied the 
earth's surface as completely, and almost as exclusively, as 
the reptiles had done during the middle ages of geological 
time. 

The reactions of insects and flowers are universally 
admitted, 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 puzzling 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 
latter epoch, is most startling. Such a change was, however, 
absolutely 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 
potentialities 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 
delicacies, and the refinements of his existence — almost all 



EXTENSIONS OF DARWINISM 283 

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, which 
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 he became able to profit by them must surely be 
accepted as additional evidence 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 development of man's spiritual nature. 

In furtherance of this object 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 Mesozoic 
reptiles by endowing them with such a limited amount of 
intelligent vitality as 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 



284 THE WORLD OF LIFE 

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 
assumed 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 essenti- 
ally 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 
different 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 drawn 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 organise a brain such as is required for the 
manifestation of that limited amount of mind and no more. 

Thus and thus only, as it seems to me, can we under- 
stand the raison d'etre of these small-brained animals. They 
were outgrowths of the great tree of life for a temporary 
purpose, to keep down 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 sufficient 
amount of varied form and structure, from which they 
could, when better conditions prevailed, at once start on 
those wonderful diverging lines of advance which have 
resulted in the perfected and glorious life-world in the midst 
of which we live, or ought to live. 



XIII 



EXTENSIONS OF DARWINISM 285 



This view of the purport, the meaning, and the higher 
function of the great and varied life-world brings us by a 
different 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 comparative rural and urban death-rates. Yet we 
have no legislator, 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, there- 
fore, take this opportunity of showing kow 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 supply 
the increased population. But where is the necessity ? Why 
provide for a population which need never have existed, and 
whose coming into existence will be an evil and of no 
possible use to any human beings except the landowners and 
speculators who will make money by the certain injury of 
their fellow-citizens ? If the House of Commons and the 
London County Council are not the bond-slaves of the land- 
owners and speculators, they have only to refuse to allow 
any further water-supply to be provided for London except 
what now exists, 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 ques- 
tion of your further growth." By that time, probably, there 
will be no public demand for enlarging our " wens " and a 
very strong and stern one for their cure or their abolition. 



CHAPTER XIV 

BIRDS AND INSECTS : AS PROOFS OF AN ORGANISING 
AND DIRECTIVE LIFE-PRINCIPLE 

If we strip a bird of its feathers so that we can see its body- 
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 mammals, but in the wing and tail-feathers 
form an essential part of the structure of each species, 
without which it is not a complete 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 mammal 
which t has lost its limbs, tail, and teeth. 

Although birds are so highly organised as to rival 
mammals 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 complete loss of the teeth, while the digits of the 
fore limb are reduced to three, the bones of which are more 
or less united, and, though slightly movable, are almost 
entirely hidden under the skin. 

286 



ch. xiv PROOFS OF ORGANISING MIND 287 

The earliest fossil bird, the Archaeopteryx, had three 
apparently free and movable digits on the fore limbs, each 
ending in a distinct claw ; while the two bones forming the 
forearm 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 vertebrae, 
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 
retained 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 
membranous-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, 
that which most clearly implies the working out of a pre- 
conceived design in a new and apparently most complex 



288 THE WORLD OF LIFE chap. 

and difficult manner, yet so as to produce a marvellously 
successful result. 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 such 
a manner as to combine great strength with extreme lightness 
and the most perfect flexibility. In order to produce this 
more perfect instrument for flight the plan of a continuous 
membrane, as in the flying reptiles (whose origin was 
probably contemporaneous with that of the earliest birds) 
and flying mammals, to be developed at a much later period, 
was rejected, and its place 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 outgrowths so 
wonderfully attached and interlocked as to form a self- 
supporting, highly elastic structure of almost inconceivable 
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 growth, or by any adhesive 
exudation, but by the mechanical structure of the delicate 
hooked lamellae of which they are composed. 

The two illustrations here given (Figs. 108, 109) 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. The slender barbs or j 
ribs of which the web of the feather is made up can be 
best understood by stripping off a portion of the web and 
separating two of the barbs 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 easily seen as in the view 
and section here given. The barbs (B, B in the figures) are 



:■ 



XIV 



PROOFS OF ORGANISING MIND 289 



elastic, horny 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 

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. 








Wnmrr 



b>. 



B 



Fig. 109. — Oblique Section through the Proximal Barbules in a plane parallel 
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.) 

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 of such slight motions 
as may be required during use, while remaining interlocked 
with the barbules of the adjoining barb in the manner just 
described. They are the essential elements of the feather, 
on which its value both for flight and as a protective clothing 

U 



290 THE WORLD OF LIFE 

depends. Even in the smallest wing-feathers they are 
probably a hundred 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 completely impervious 
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 developed 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 unable to obtain any shelter from violent 
storms or blizzards. Yet, as every single feather is movable 
and erectile, the whole body 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 during the rapid down-stroke the combined feathers 
constitute a perfectly air-tight, exceedingly strong, yet highly 
elastic instrument for flight ; while the moment the upward 
motion begins 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 automatic- 
ally as air-tight as before. Thus the effective down-strokes 
follow each other so 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! 



xiv PROOFS OF ORGANISING MIND 291 

instrument which the organism has built up, and which then 
ceases to form an integral portion of it — is, in fact, dead matter. 
Hence, in no part of the fully grown feather is there any 
blood circulation or muscular attachment, except as regards 
the base, which is firmly held by the muscles and tendons 
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 
anything 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 conceal- 
ment ; 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 import- 
ant 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 
well 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 the size and shape characteristic of the species, 
while each of the often very diverse feathers grows in its 
right place, and reproduces 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 accurately 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 
complex form, closely resembling one or other of its parents, 



292 THE WORLD OF LIFE 

is so universal a fact that, with most people, it ceases to 
excite wonder or curiosity. Yet it is to this day absolutely 
inexplicable. No doubt an immense deal has been discovered 
of the mechanism 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 con- 
jectures. 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 — carbon, 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 protoplasm. These are silicon, 
fluorine, bromine, iodine, aluminium, and manganese. 1 

Protoplasm is so complex a substance, not only in the 
number 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 three groups 
of chemical substances — proteids, carbohydrates, and fats. 
The 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, consist 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, caffeine, and many others, have 
been produced in the laboratory, 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 
wonderfully complex as to be almost impossible of deter- 

1 Verworn's General Physiology, p. ioo. 









acies, 

S tier 

i 



XIV 



PROOFS OF ORGANISING MIND 293 



mination. As examples of recent results, haemoglobin, the 
red colouring matter of the blood, was found by Preyer in 
1866 to be as follows — 

^600^960'^154^ e i^3^'l79' 

showing a total of 1894 atoms, while Zinoffsky in 1855 
found the same substance from horse's blood to be — 

C H N O Fe S 

^-'712 xa 1130 i>l 214 w 245 r c l°2> 

showing a total of 2304 atoms. Considering the very small 
number of atoms in inorganic compounds, and in the simpler 
vegetable and animal products, caffeine containing only 23 
(C 7 H 7 (CH 3 )N 4 2 ), the complexity of the proteids will be 
more appreciated. 

Professor Max Verworn, from whose great 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 dead and the living cell, and admits that our 
knowledge of the latter is extremely imperfect. He enu- 
merates many differences between them, and declares that 
" substances exist in living 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 still preserving the highly complex cell in its integrity 
for indefinite periods ; its resistance 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 his highly elaborate volume of 600 closely printed 
pages, dealing with every aspect of cell-structure and physio- 
logy 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 genera- 



294 THE WORLD OF LIFE 

tion 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 perfection of structure and co-ordination 
of parts, such as characterises every living thing ! 

Let us now recur to the subject that has led to this 
digression — the feathers of a bird. We have seen that a 
full-grown wing-feather may consist of more than a million I 
distinct parts — the barbules, which give the feather its | 
essential character, whether as an organ of flight or a mere 
covering and heat-preserver 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 produce 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 

■■k 



& 



m 
k 
rcre 






Mra 



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, what is the constructive power which 
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, 
what is the nature of the power which determines that every 
separate feather shall always " grow " into its exact shape 






n 



r 



XIV 



PROOFS OF ORGANISING MIND 295 



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 agency determines the distribution of the colouring 
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 ? 

Now, in none of the volumes on the physiology of 
animals that I have consulted can I find any attempt what- 
ever to grapple with this fundamental question of the 
directive power that, in every case, first secretes, or as it 
were creates, out of the protoplasm of the blood, special 
molecules adapted for the production of each material — 
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 build up with great 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 wholly external, and of being familiar to 
every one. It is also easily accessible for examination 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, 
helps us to realise to a slight extent the nature and laws of 
heredity, but leaves the great problem of the nature of the 
forces at work in growth and reproduction as mysterious as 






296 THE WORLD OF LIFE 







RS 



ever. Modern physiologists have given us a vast body of 
information on the structure of the cell, on the extreme 
complexity of the processes 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 enlightenment. They will not even admit 
that any such constructive guidance is required ! 

A Physiological Allegory 

For an imaginary parallel to this state of things, let us 
suppose some race of intelligent beings who have the power 
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 would 
appear to move spontaneously ; 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 them- 
selves 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 separate 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 



rate] 



tea 
IT 



xiv PROOFS OF ORGANISING MIND 297 

earth ; and to those who pointed to the result of all this 
" motion 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 
same size as ourselves, can only be seen by microscopes, and 
that with improved instruments the various tools we use, as 
well as our articles of furniture, our food, and our table- 
fittings (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 disappear ; and when all this is observed to recur 
at certain definite intervals every day, there would be great 
jubilation over the discovery, and it would be loudly pro- 
claimed 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 
physiology 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 Insecta, or insects, 
which may be briefly defined as ringed or jointed (annulose) 
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 
supply 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 meta- 
morphosis, that is, which in their larval state are the most 



298 THE WORLD OF LIFE 

completely unlike their perfect condition. They comprise 
the great orders Lepidoptera (butterflies and moths), 
Coleoptera (beetles), Hymenoptera (bees, ants, etc.), and 
Diptera (two-winged flies), the first and last being those 
which are perhaps the most important as bird-food. In all 
these orders the eggs produce a minute grub, maggot, or 
caterpillar, as they are variously called, the first having a 
distinct head but no legs, the second 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 former has simple 
eyes, biting jaws, and no sign of wings ; the latter, large 
compound eyes, a spiral suctorial mouth, and usually four 
large and beautifully coloured wings. 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 perfect 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 observers, 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 mysterious 
as before. Years of continuous research have been devoted 
to the subject, and volumes have been written upon it. One 
of the most recent English writers is Mr. B. Thompson 
Lowne, F.R.C.S., who has devoted about a quarter of aj 
century to the study of one insect — the common blow-fly — 



XIV 



PROOFS OF ORGANISING MIND 299 



on the anatomy, physiology, and development of which 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 and Lepidoptera, he believes 
them to be the most numerous in species of all the orders of 
insects. I will now endeavour to state in the fewest words 
possible the 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 complete meta- 
morphosis — the cockroaches — the young emerge from the 
egg with the same general form as the adult, but with 
rudimentary wings, the perfect wings 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 formation. 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 somewhat resembling 
the cockroach, but even lower in the scale of organisation, 
the earlier stages of life have become more simplified, 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 ; while 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 earliest stage of life 
towards a simple feeding machine took place at the period 



300 THE WORLD OF LIFE chap. 






of the successive moults, but it being more advantageous to 
have the larva stage wholly in the form best adapted for the 
storing up of living protoplasm, the retrogressive variations 
became step by step earlier, and at length occurred within 
the egg. At this early period certain rudiments of wings 
and other organs are represented by small groups of minute 
cells termed by Weismann imagined discs, which were 
determined by him to be the rudiments of the perfect 
insect. These persist unchanged 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 i 
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 thenceforth 
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 
decomposition of the cells, but not apparently of the proto- 
plasmic molecules — to be found elsewhere in the whole 
course of organic evolution ; and it introduced new and 
tremendous difficulties 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 rapidly 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 develop- 
mental growth. This growth has been followed, step by step 
through all its complicated details, by Mr. Lowne and many 






■ 






XIV 



PROOFS OF ORGANISING MIND 301 



other enthusiastic workers ; but I will call attention here 
only to the special case of the Lepidoptera, because these 
are far more popularly known, and the special feature which 
distinguishes them from most other insects is familiar to 
every one, and can be examined by means of a good pocket 
lens or microscope of moderate power. I allude, of course, 
to the wonderful scales which clothe the wings of most 
butterflies and moths, and which produce the brilliant 
colours and infinitely varied patterns with which they are 
adorned. Of course, the still more extensive order of the 
Coleoptera (beetles) present a similar phenomenon in the 
colours 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 expand 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 or 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 to be formed as 

minute bag-like sacs filled with protoplasm ; the succeeding 

whiteness is caused by the protoplasm being withdrawn and 

the sacs 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 brilliant colours 

seem to be produced from the dull yellow pigment by 

chemical changes which occur within the scales. A few 

days before emergence the scales become fully grown, as 

highly complex structures formed of parallel rows of minute 

cells, each scale with a basal stem which enters a pocket of 

the skin or membrane, which pockets send out roots which 

seem to penetrate through the skin. 1 Another complication 

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 very condensed abstract. 



302 THE WORLD OF LIFE 

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 proto- 
plasm. Its limbs, its motions, its senses, its internal 
structure, are all adapted to this one end. When fully 
grown it ceases to feed, prepares itself for the great change 
by various modes of concealment — 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 — become 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 compar- 
able 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 construction than those 
of the bird, but apparently quite as well adapted to its 
needs, develop a more or less complete covering of minute 
scales, whose chief or only function appears to be to paint 
them with all the colours and all the 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 
themselves. The butterflies, or diurnal Lepidoptera alone, 
not only present us with a range of colour and pattern and 



xiv PROOFS OF ORGANISING MIND 303 

of metallic brilliancy fully equal (probably superior) to that 
of birds, 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, the special organs upon which these colours and 
patterns are displayed 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 exquisite plumage of birds. It is true 
that in some cases, these scales have been modified into 
scent-glands 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 Chapter 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 that 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 almost always 
their 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 enemies from attacking a vital part, or, 



304 



THE WORLD OF LIFE 



CHAP. XIV 



in the smaller species may alarm the enemy by its sudden 
flash with change of position. But while the colours are 
undoubtedly useful, the mode of producing them seems 
unnecessarily elaborate, and adds a fresh complication and 
a still greater difficulty in the way of any mechanical or 
chemical conception of their production. 



CHAPTER XV 

GENERAL ADAPTATIONS OF PLANTS, ANIMALS, 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 
Lubbock (now Lord Avebury), Hermann Miiller, and many 
other writers. I have also myself given a general account 
of the whole subject both in my Tropical Nature, and my 
Darwinism ; but as there are some points of importance 
which, I believe, have not yet been discussed, and as the 
readers of this volume may not be acquainted with the vast 
extent of the evidence, 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 
evidence is that those whose 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 : " I have come to this conclusion (that flowers 
are coloured to attract insects) from finding it an invariable 
rule that when a flower is fertilised by the wind it never has 
a gaily-coloured corolla." Then a few lines farther on he 
adverts to beautifully coloured fruits and says : " But the 
beauty serves merely as a guide to birds and beasts, in order 
that the fruit may be devoured and the matured seed 

305 X 



306 THE WORLD OF LIFE chap. 

disseminated ; I infer that this is the case 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." x 

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 primrose, 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 careful experiments made by himself 
during many years, serving as the justification for the few 
general observations as regards flowers and insects, which 
form the only reference to the subject 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 
beneficial 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 — Papilionaceae, Labiates, Schrophu-'i 
lariaceae, Orchideae, and others — have become thus shaped to 
facilitate 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 wonder- 
ful variety in form and structure, and the beauty or con- 
spicuousness 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 adaptations in flowers to secure 
them from injurious insects or from the effects of rain or wind 

1 Origin of Species, 6th edition, p. 161. 



xv GENERAL ADAPTATIONS 307 

in damaging the pollen or the stigmas, as beautifully shown 
in Kerner's very interesting volume on Flowers and their 
Unbidden Guests — a book that forms an admirable sequel 
to Darwin's works, and is equally instructive and interesting. 

Of late years writers who are very imperfectly acquainted 
with 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 may be 
here noticed as illustrative of the kind of opposition to which 
Darwinism is exposed. The bee - orchis of our chalky 
downs, though conspicuously coloured and with a fully- 
developed labellum, like the majority of its allies which 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, but they rarely produce so many seed-capsules as 
ours ; but, strange to say, an allied species {Ophrys scolopax) 
is in one district fertilised by insects only, while in another 
it is self-fertilised. Again, in Portugal, where many species 
of Ophrys are found, very few of the flowers are fertilised 
and very few ripe seed-capsules are produced. But owing 
to the great number of seeds in a capsule, and their easy 
dispersal by wind, the plants are abundant. These and 
many other facts show that for some unknown cause, orchises 
which are exclusively insect-fertilised, are liable to remain 
unfertilised, and when that is the case it becomes advantageous 
to the species to be able to fertilise itself, and this has 
occurred, partially in many species, and completely in our 
bee-orchis. 

I may remark here that the name " bee-orchis " is mis- 
leading, as the flower does not resemble any of our bees. But 
the very closely allied " spider orchises " resemble spiders 
much 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 whom 
even spiders on their noses or lips would be disagreeable. 



308 THE WORLD OF LIFE chap. 

Mr. Henry O. Forbes observed, in Sumatra, that many 
tropical orchids with showy flowers, which 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, however, there is any danger of extinction the great 
variability of orchids, which at first enabled them to become 
so highly specialised 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 insects 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 eating 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 wholly 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 (Ranunculus acris, R. repens, and R. bulbosus) are 
so constructed that they can be cross-fertilised by a great 
variety of insects, and as a matter of fact are so fertilised. 
H. Muller grouped these three species together, as the same 
insects visit them all, and he found that they were attractive 
to no less than sixty different species, including 23 flies, 11 
beetles, 24 bees, wasps, etc., and 5 butterflies. 

Any readers who are not satisfied with Darwin's own 
statements on this subject should examine M tiller's Fertilisa- 
tion of Flowers (translated by D'Arcy W. Thompson), in 






xv GENERAL ADAPTATIONS 309 

which details are given of the fertilisation of about 400 
species of alpine plants by insects, while a General 
Retrospect gives a most valuable summary of the con- 
clusions and teachings on the whole subject. As regards 
the general question of the uses and purposes of colour in 
nature, the late Grant Allen's interesting and philosophical 
work on The Colour Sense should be 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 fascinating style of the book I will quote the 
following paragraph comparing insect-agency with that of 
man in modifying and beautifying 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 compared 
with the immense revolution wrought in the features of nature by 
the unobtrusive insect. Half the flora of the earth has taken the 
imprint of his likes and his necessities. While man has only tilled 
a few level plains, a few great river-valleys, a few peninsular mountain 
slopes, leaving the vast mass of earth untouched by his hand, the 
insect has spread himself over every land in a thousand shapes, and 
has made the whole flowering creation subservient to his daily wants. 
His buttercup, his dandelion, and his meadow-sweet grow thick in 
every English field. His thyme clothes the hill-side ; his heather 
purples the bleak grey moorland. High up among the Alpine 
heights his gentian spreads itself 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 earth into a bound- 
less 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 
attributing the origin and development of flowers to the 
visits of insects, and the consequent advantage of rendering 
many species 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 explained. 

In my book on Tropical Nature I devoted two chapters 



310 THE WORLD OF LIFE chap. 

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 colours. 
The heavenly blue of the firmament, the glowing tints of sunset, 
the exquisite purity of the snowy mountains, and the endless 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 ornamented 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 nature is 
indisputable. The child and the savage alike admire the gay 
tints of flower, bird, and insect ; while to many of us their con- 
templation brings a solace and enjoyment which is wholly beneficial. 
It can then hardly excite surprise that this relation was long thought 
to afford a sufficient explanation of the phenomena of colour in 
nature, and this received great support from the difficulty 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 raiment, and the prickly cactus be 
adorned with crimson bells ? Why should 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 emotions 
may not be another, and more important use which they subserve 
in the great system of the universe ? " 

The above passage was written more than forty years 






XV 



GENERAL ADAPTATIONS 311 



ago, and I now feel more deeply than ever that the con- 
cluding 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 substantially correct. 

The first thing to be noticed is, that the insects whose 
perceptions 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 same 
as our own, or even at all closely resembling it, is highly 
improbable. Still more improbable is it that their percep- 
tion of colour is the same as ours, their organ of sight and 
their whole nervous system being so very different, and 
the exact nature of their senses being unknown. 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 otherwise alike and which have no perfume. 
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 normally 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, 



312 THE WORLD OF LIFE 

of indescribable charm, which nature's forms and colouring 
so often gives us, is still farther 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 with some of our 
higher intellectual achievements, that the total absence of 
perception of colour would have checked, or perhaps wholly 
prevented, all those recent discoveries in spectroscopy which 
now form so powerful a means of acquiring an extended 
knowledge of the almost illimitable universe. 

I venture to think, therefore, that we have good reason 
to believe that our colour-perceptions have not been developed 
in us solely by their survival -value in the struggle for 
existence ; which is all we could have acquired if the views 
of such thinkers as Grant Allen and Professor Haeckel 
represent the whole 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 flowers 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 
order that they may attach themselves to the fur of quad- 
rupeds or the feathers of birds, and thus obtain extensive 



X v GENERAL ADAPTATIONS 313 

dissemination. All this was clearly seen and briefly stated 
by Darwin, and has been somewhat fully developed by 
myself in the work already quoted : but there is one point 
on which I wish to make 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 unripe and brown when they fall upon the 
ground among the decaying foliage. Moreover, their outer- 
coverings are often prickly, as in the sweet-chestnut, or 
bitter as in the walnut, while their 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, I 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 interest and exhibits one of the curious and 
indirect ways in which nature works for the preservation of 
species, both in the vegetable 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 
between 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 



314 THE WORLD OF LIFE chap. 

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 
herbivorous mammals. For most of these go in herds, 
such as swine, peccaries, deer, cattle, horses, etc., and when 
such animals are startled while feeding and scamper away, 
two results, useful to the species whose fruit they are feeding 
upon, follow. As the acorns, chestnuts, etc., usually lie thickly 
on the ground, some will be driven or kicked along with 
the herd ; and this being repeated many times during a 
season and year after year, a number of seeds are scattered 
beyond the limits of the parent 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 coming to maturity. 

Now 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 Brazil-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 be broken open with an axe by the seed-collectors, : f 
is another example. This is said 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 ; , . 



tv 



GENERAL ADAPTATIONS 315 



scattered to a considerable distance by the feet of tapirs, deer, 
>r peccaries, and when at last the seeds fell out, perhaps 
lided by the teeth or feet of these animals, some of them 
vould almost certainly be trodden into the ground, and this 
vould be facilitated by their sub-angular shape. If this is 
he mode of dispersal it has proved very successful, for the 
ipecies is widely scattered in moderate-sized groves over a 
:onsiderable portion of the Amazonian forests. The main 
acts and probabilities clearly point to the conclusion that 
he extensive group of nut-like fruits or seeds are intended 
o be eaten, not by birds while on the trees, but by ground- 
eeding animals — to be devoured wholesale, in order to dis- 
>erse and save a few which may germinate and produce 
mother generation of trees. 

The Colours of Plants and Animals in relation to Man 

The views of Haeckel and of the whole school of 
VIonists, as well as of most of the followers of Spencer and 
3arwin, are strongly antagonistic to the idea that in the 
various groups of phenomena we have so far touched upon 
here has been in any real sense a preparation of the earth 
or man ; and those who advocate such a theory are usually 
reated with scorn as being unscientific, or with contempt as 
)eing priest-ridden. Darwin himself was quite distressed at 
ny rejection of his own conclusion — that even man's highest 
qualities and powers had been developed out of those of the 
ower animals by natural or sexual selection. Several critics 
iccused me of " appealing to first causes " in order to get 
)ver difficulties ; of maintaining that " our brains are made 
>y God and our lungs by natural selection " ; and that, in 
Joint of fact, " man is God's domestic animal." This was 
vhen I published my Contributions to the Theory of Natural 
selection, in 1870, its last chapter on The Limits of 
Natural Selection as applied to Man, being the special 
)bject of animadversion, because I pointed out that some of 
nan's physical characters and many of his mental and moral 
acuities could not have been produced and developed to 
heir actual perfection by the law of natural selection alone, 
because they are not of survival value in the struggle for 
xistence. 



316 



THE WORLD OF LIFE 



CHAP. 



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, 
we require to postulate the continuous action and guidance 
of higher intelligences ; and further, that these have probably 
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 growth in the animal world, and especially as manifested 
in the feathers of birds and the transformations of the 
higher insects, are absolutely unintelligible and unthinkable 
in the absence of such intelligence, we must go a step 
farther and assume, as in the highest degree probable, a 
purpose 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 appearance, plants and animals in many diverging 
lines had approached their highest development ; 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 seem to be so carefully adapted to 
our wants during our growing civilisation were really 
prepared for us. If this be so, it follows that the much- 
despised anthropomorphic view of the whole development 
of the earth and of organic nature was, after all, the 
true one. 

But if the view now advocated is not so wholly un- 



XV 



GENERAL ADAPTATIONS 317 



scientific, so utterly contemptible as it has hitherto been 
declared to be by many of our great authorities, it is 
certainly advisable to show how various facts in nature 
bear upon it and are explained by it. I will therefore 
now add a few more considerations 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 they do perceive what are to us broad 
differences of colour, but we have no means whatever of 
knowing what 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 
between 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 sugges- 
tive that the orang-utan of Borneo feeds on the large, green, 
spiny Durian fruit ; and I have also seen them feeding 



? 



318 THE WORLD OF LIFE 

on a green fruit which was repulsively bitter to myself. 
Our nearest relatives among existing quadrupeds do not 
therefore seem to have any need of a refined colour-sense. 
Why then should it have been so highly developed in us ? 
It was one of the fundamental maxims of Darwin that 
natural selection could not produce absolute, but only 
relative perfection ; and again, that no species could acquire 
any faculty beyond its needs. 

The same arguments will apply even more strongly in 
the case of insects. They appear to recognise the colours, 
the forms, and the scents of flowers, but we can only 
vaguely 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 improbable that there is any identity even in their 
lower mental faculties with those of birds. For the colour- 
sense is mental, not physical ; it depends partly on the 
organ of vision, but more fundamentally on the nature 
of the nervous tissues which transform the effects of light- 
vibrations into the visual impressions which we recognise 
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 may 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 nearly the same 
range of the colour-scheme, and a very similar intensity, 
brilliancy, and purity of colour in particular cases ; which 
is highly remarkable if their respective needs were the 
only efficient causes in the production of these colours. 
Looking first at flowers, how very common and conspicuous 
are those of a yellow colour, yet far beyond the average 
are the rich orange petals of the Escholtzia and the glisten- 
ing splendour of some of our buttercups ; reds and purples 
are innumerable, yet in the Lobelia fulgens and some other 
flowers we reach an intensity of hue which seem to us 
unsurpassably beautiful ; blues of the type of the cam- 
panulas or the various blue liliaceae are all in their way 
charming, but in the blue salvia (Salvia patens) the spring 






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GENERAL ADAPTATIONS 319 

gentian {Gentiana verna), and a few others, we perceive a depth 
and a purity of hue 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 
infinity 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 locality and flower at the 
same time. 

Special Cases of Bird Coloration 

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 farther in modifica- 
tions 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, 
appearing 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 
refinements 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 feathery dome of the umbrella-bird, to the large richly 
coloured crest of the royal fly-catcher of Brazil, and the 
marvellous blue plumes from the head of the fern-bearing 
bird of paradise (P teridophora A/derti), with a thousand others 
hardly inferior, and we shall more than ever feel the want of 
some general and fundamental cause of so much beauty. 

All this wealth of colour, delicacy of texture and exuber- 
ance of ornament, has been explained hitherto as being utili- 
tarian in two ways only : (i) that they are recognition-marks 
of use to each species, more especially during its differentiation 
as a species ; and (2) as influencing female choice of the 
most ornamental males, and therefore of use to each species 



320 THE WORLD OF LIFE 

in the struggle for existence. The former I have, I think, 
proved to be a true cause ; the latter I reject for reasons 
given in my Darwinism. I there give an alternative solution 
of the problem which I still think to be fundamentally- 
correct and which has been arrived at by Weismann and 
others from theoretical considerations to which I may advert 
later on. 



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Coloration of Insects 

Passing now to the order of insects which perhaps ex- 
hibits the greatest range of colour-display in the whole of 
the organic world — especially in the order Lepidoptera, we 
find the difficulties in the way of a purely utilitarian solution 
still greater. Any one who is acquainted with this order of 
insects in its fullest development in the equatorial zone of 
the great continents, will recognise how impossible it is to 
give any adequate conception of its wealth of colour-decoration 
by a mere verbal description. Yet the attempt must be 
made in order to complete the argument I am founding 
upon a consideration of the whole of the facts of organic . 
coloration. 

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 Chaaxes Jason, 
and many others. But these are absolutely as nothing i 
compared to the wealth of colour displayed in the eastern 
and western tropics, where the average size is from two to j 
three times ours, and the numbers, both in species and i 
individuals at least ten times as great. Not only is there 
every tint of red, yellow, blue and green, on ground-colours 
of black or white and various shades of brown or buff, but 
we find the most vivid metallic blues or silky yellows 
covering a large portion of the wing-surface or displayed 
in a variety of patterns that is almost bewildering in its 
diversity and beauty. 

As a few examples, the Callithea sapphira of the Amazon 
is of a soft, celestial blue that the finest lobelia or gentian 
cannot surpass. The grand Omithoptera Amphrisius and its 



■*■:■■ 



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XV 



GENERAL ADAPTATIONS 321 



allies have the hind wings of an intense yellow with a silky- 
lustre, while O. Priamus and many allied species are richly 
adorned 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 Epimachidae of New 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 Lycaenidae 
and Erycinidae 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 Heliconidae and Danaidae, 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 displayed elsewhere. These are to be found in a 
few species only in both hemispheres, and are therefore the 
more remarkable. The largest butterfly to exhibit this 
form of colour is the Ornithoptera magellanus, from the Philip- 
pines, whose golden-yellow wings, when viewed obliquely 
acquire the changing 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 (the Bismarck Archipelago) there is 
a day-flying moth (Burgena chalybeatd), one of the Agaristidae, 
whose wings change from black to blue and a fiery opalescent 
red. In tropical America there is a group of butterflies of 
the genus Papilio, which are very abundant both in species 
and individuals, whose velvet-black wings have a few bands 

Y 






322 THE WORLD OF LIFE 

or spots of blue or green on the upper pair, while the lower 
have a band of spots near the posterior margin of a brilliant 
crimson. Among perhaps a hundred species with this 1 
general style of coloration, there are a few (perhaps a | 
dozen) in which the red of the hind wings, when viewed very | 
obliquely from behind, changes into opalescent and then! 
into a curious bluish phosphorescence of intense brilliancy. 

I am informed by Dr. K. Jordan (of the Tring Zoological 
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 Mr. Bates gave to one of the 
new species he described, the name of Papilio phosphorus, 
One of the small Erycinidae {Euselasia prceclard) found in the 
Upper Amazon valley, is of a yellow buff colour, with al 
wonderful opalescent reflection which is said to be the mos 
intense and brilliant in the whole order of Lepidoptera an 
probably the most brilliant colour known. 

All metallic reflections in the animal world are what ar> 
called interference-colours, and are produced by excessively 
fine lines or rugosities on polished surfaces, or by equally 
thin transparent laminae. It is probable that in the remark-, 
able changing glows now described, both these causes may 
come into play, producing, when viewed at certain angles, 
an intensity of hue resembling those of the finest opalsf 
or sometimes imitating the most brilliant glow - worms 
or fire-flies by means of reflected light. It seems probable 
that these rare hues may be of a protective nature, since <; 
pursuing bird might be startled by the sudden flashing out o| 
so brilliant a light and thus allow the insect to escape ; bu'i 
that does not render it more likely that the infinitel} 
complex arrangements by which such structures are produce^ 
and transmitted unfailingly to offspring, should have beer; 
brought about for this purpose alone, when thousands o 
other species arrive at the same end by simpler means. 

Now if there was a difficulty in the view that all th< 
wealth of colour and beauty in birds has been developec 
solely on account of its utility to themselves, that difficult} 
becomes greatly increased in the case of these insects. Th( 
described butterflies alone are already far more numeroui 



IB) k 



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XV 



GENERAL ADAPTATIONS 323 



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 possibilities 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 perhaps 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 flower, 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 wave-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 we really know is, that they appear to perceive differences 
where we perceive colour, but it has not been proved how 
far this perception extends, since in the most intelligent of 
these, dogs 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 the theory of the develop- 
ment of the colour-sense through its utility, receives least 
support from those animals which are nearest to us, and 
from which we have been corporeally developed — the 
mammals ; rather more support from those which have had 
a widely different origin — the birds ; and apparently most 
from those farthest removed from us — the insects, for whom 
it has been claimed that we owe them all the floral beauty 
of the vegetable kingdom, through their refined perception of 



324 



THE WORLD OF LIFE 



CHAP. XV 



! 



differences of form and colour. This seems to me to be a 
kind of reductio ad absurdum, 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 enjoyment of colour we 
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 regard to his 
enjoyment of scenery and of music, " gratuitous gifts," and 
as such are powerful arguments for " a benevolent Author 
of the Universe." 1 

1 See Darwinism (3rd ed. 1901), p. 478, Appendix. 



CHAPTER XVI 

THE VEGETABLE KINGDOM IN ITS SPECIAL RELATION 

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 
benefiting the animal. This harmonious co- adaptation 
cannot therefore 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 sustenance 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 considerable range in their hardness, in their 
durability when exposed to the action of water or of the 
soil, in their weight and in their elasticity, render them 

325 



326 THE WORLD OF LIFE 

serviceable to him in a thousand ways which are totally j|M netl 

til 



removed from any use made of them by the lower animals. 

Few of these qualities seem essential to themselves as 
vegetable 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 be dangerous ; or subject to rapid decay by the action 
of air, or of water, or of sunshine, so as to be suitable for 
temporary purposes only. With any of these defects they 
might have served the purposes of the animal world quite 
as well as they do now ; and their actual properties, all 
varying about a mean value, which serves the infinitely 
varied purposes to which we daily and hourly apply them, 
may certainly be adduced as an indication that they were 
endowed with such properties in view of the coming race 
which 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 
timber as above indicated might mean let us remember that 
from before the dawn of history down to about the middle 
of the last century every ship in the world was built of 
wood. Had no wood existed suitable for sea-going vessels, 
the whole course of history, and perhaps of civilisation, 
would have been different. Without ships the Mediterranean 
would have been almost as impassable as was the Atlantic. 
America would be still unknown, as well as Australia and 
possibly South Africa ; and the whole world would be for 
us smaller than in the days before Columbus. And all this 
might have happened had the nature of vegetable growth, 
while differing little in external form and equally well 
adapted for unintelligent animal life, not possessed those 
special qualities which fitted it for ministering to the varied 
needs of intellectual, inventive, and ever advancing man. 

But, even with the whole vegetable world in its outward 
aspect and mechanical properties exactly as it is now, there 
are still a thousand ways in which it ministers to the needs 
of our ever-growing civilisation, which have little or no 
relation to the animal world which grew up in dependence 
on it. Leaving out of consideration the vast number of 
fruits, and cereals, and vegetables which supply him with 



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XVI 



PLANTS IN RELATION TO MAN 327 



varieties of food, which may be of more importance to man 
in the future than they 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 pharmacopoeias 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 altogether imaginary, very large numbers 
still hold their place as of real and often of inestimable 
value. To name only 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, podophyllin, quinine, rhubarb, sarsaparilla, 
and a host of others. 

To these we may 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, 
tragacanth, asafoetida, gamboge, etc. 

Among the numerous dyes are arnotto, 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, 
peppermint, orris-root, sandalwood, sassafras, tonquin- 
beans, vanilla, and the many essential oils from highly 
perfumed fruits and flowers. 

Of foods and drinks not used by the lower animals, are 
irrowroot, tapioca, sago, sugar, wine, beer, tea, coffee, and 
:ocoa, the last six, when used in moderation, being among 
:he choicest gifts of nature. 

There remain a number of vegetable products invaluable 
For arts and manufactures — cotton and flax for clothing, 



328 THE WORLD OF LIFE 

hemp for cordage, rattan and bamboo for tropical furniture, 
boxwood for wood -engraving, gutta-percha for machine | 
belts and a great variety of economic uses, and lastly 
india-rubber, one of the greatest essentials of our chemical 
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 remain 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 significance. 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 by-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 quantity 
during the whole life of the plant, but are transformed into 
such as are of unmistakable value to civilised man. It is 
almost inconceivable that the exquisite fragrance developed 
only by roasting the seed of the coffee shrub 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 only of the thousands of species having a protective 
milky sap. 

Indications of a Directive Mind 

Before leaving this branch of my subject, I must say a 
few words on the indications afforded by these varied pro- 
ducts 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 



xvi PLANTS IN RELATION TO MAN 329 

insect's transformations, 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 what 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 
employ 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 constituents of living organisms remain far beyond his 
powers of synthesis. 

The conditions under which nature works in the vegetable 
kingdom are the very opposite of all this. Starting from 
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 are 
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 



330 THE WORLD OF LIFE 

a hundred feet or more above the surface, by means of forces 
whose nature and exact mode of operation is still a mystery ; 
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 briefly 
referred to. 

The living plant not only builds up its own marvellous 
structure out of a few elements supplied to it either in a 
gaseous or liquid state, but it also manufactures all the 
appliances — cells, vessels, fibres, etc. — needful for its com- 
plex laboratory-work in producing the innumerable by- 
products 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 
describe the minute structure of the organs of plants or 
animals, and to trace out as far as possible the changes that 
occur during growth, without any reference to the unknown 
and unintelligible forces at work. As Weismann has stated, 
the fundamental question — " the causes and mechanism by 
which it comes about that they (the gemmules or physio- 
logical units) are always in the right place and develop into 
cells at the right time " — is rarely or never touched upon. 1 
Modern theories of heredity take for granted the essential 
phenomena of life — nutrition, assimilation, and growth. 

I find, however, that Professor Anton Kerner, in his 
great work on The Natural History of Plants, fully recog- 
nises 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 distinct 
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 success- 

1 The Germ-Plasm, \>. 4. 



xvi PLANTS IN RELATION TO MAN 331 

fully 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 under 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 energy. 
Therefore, I do not hesitate again to designate as ' vital force ' this 
natural agency, not to be identified with any other, whose immediate 
instrument is the protoplasm, and whose peculiar effects we call life. 
The atoms and molecules of protoplasm only fulfil the functions 
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 in- 
consistent with the fact that living bodies may at the same time be 
subject to other natural forces" (vol. i. p. 52). 

And again, after discussing the various effects produced 
by that wonderful substance chlorophyll, he says : 

"We see the effective apparatus, we recognise the food-gases 
and food-salts collected for working up, we know that the sun's rays 
act as the motive force, and we also identify the products which 
appear completed in the chlorophyll granules. By careful com- 
parison of various cells containing chlorophyll, having found by 
experience that under certain external conditions the whole apparatus 
becomes disintegrated and destroyed, it is indeed permissible 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 material 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 that displacement of the 
atoms called decomposition, but of that process which is known as 
combination or synthesis'''' (vol. i. p. 377). 

I have made these quotations from one of the greatest 
German writers 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 



332 THE WORLD OF LIFE 

reached from a consideration of some of the broader pheno- 
mena of animal life and organisation. In the last paragraph 
quoted he even shows that phenomena occur during the 
growth of the plant, which are, as I suggested from other 
facts, comparable in complexity with those of the meta- 
morphosis of the higher insects, and, therefore, equally 
requiring the agency of some high directive power for an 
adequate rational explanation of them. 

I am quite aware that this view, of the earth and organic 
nature having been designed for the development of the 
human race ; and further, that it has been so designed that 
in the course of its entire evolution its detailed features and 
organisation have been such as not only to serve the 
purposes of the 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 bestow 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 enthusiastic 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. Now, 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 



i 









XVI 



PLANTS IN RELATION TO MAN 333 



I am as fully imbued with the teachings of evolution as 
they can be ; and I still uphold, as I have always done, the 
essential teachings of Darwinism. 

Darwin always admitted, and even urged, that " Natural 
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 
Variability," 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 explanation or even comprehension. He elaborated 
his theory of Panagenesis for the purpose of rendering the 
many strange facts of inheritance more unintelligible, but 
even if it were proved to be an exact representation of the 
facts it would not be an explanation, because, as Weismann, 
Kerner, and many others admit, it would not account for 
the forces, the directive agency, and the organising power 
which are essential features of growth. This is felt so 
strongly by all the great workers in physiology, that even 
Haeckel has been driven to postulate " mind, soul, or 
volition," not only in every cell but in each organic molecule 
or physiological unit. And then, to save himself from the 
slur of being " unscientific," and of introducing the very 
organising power he had derided when suggested by others, 
he loudly proclaims that his " soul-atom," though it has 
" will," is yet wholly " unconscious." 2 

I again urge, therefore, that our greatest authorities 
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 rudimentary 
mind in cell or atom. Such vague and petty suppositions, 
however, do not meet the necessities of the problem. I 
admit that such forces and such rudimentary mind-power 
may and probably do exist, but I maintain that they are 
wholly inadequate, and that some vast intelligence, some 
pervading spirit is required to guide these lower forces in 
accordance with a pre-ordained system of evolution of the 
organic world. 

If, however, we go as far as this, we must go farther. 
1 The Riddle of the Universe, p. 64. 



334 THE WORLD OF LIFE chap, xvi 

If there is a ruling and creative power to which the existence 
of our cosmos is due, and if we are its one and unique 
highest outcome, able to understand and to make use of the 
forces and products of nature in a way that no other animal 
has been able to do ; and if, further, there is any reasonable 
probability of a continuous life for us, in which we may still 
further develop that higher spiritual nature which we possess, 
then we have a perfect right, on logical and scientific grounds, 
to see in the infinitely varied products of the animal and 
vegetable kingdoms, which 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 beings. 






CHAPTER XVII 

THE MYSTERY OF THE CELL 

I HAVE already (at page 292) given a short account of the 
chemical composition of protoplasm — the highly complex 
substance now held to be the physical basis of life, and by 
one school of biologists alleged to explain, as a result of 
that complexity, all the wondrous phenomena of growth 
and development. I 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 under- 
goes during the growth or reproduction 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 described 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 expansion ; this is termed the 
" contractile vacuole," which, when it has reached its full size, 
perhaps a quarter or a fifth of the whole diameter, suddenly 
disappears, and after a little while reappears and gradually 
grows again to its maximum size. The shape of the 
Amoeba varies greatly. Sometimes it is globular and 
immovable, but most frequently it is very irregular with 
arm-like processes jutting out in various directions. By 

335 



336 THE WORLD OF LIFE 

careful watching, these are seen to increase or diminish so as 
to change the whole shape in an hour or two. But more 
curious is its power of absorbing any particles of organic 
matter that come in contact with it by gradually enclosing 
them in its substance, where after a time they disappear. 
The Amoebae are found in stagnant water full of organic 
matter, and if they are transferred to pure water 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 modified 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 Amoebae, but 
the beautiful 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 Nummulites 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 skeleton, and often living in 
colonies. Another class, the Mastigophora, 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 increase either by 
division or by giving off buds, which rapidly grow into the 
perfect form. 



XVII 



MYSTERY OF THE CELL 337 



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 in 
Chambers's Encyclopaedia says : " The absence of a circulating 
fluid, of digestive glands, nerves, sense-organs, lungs, kidneys, 
and the like, does not in any way restrict the vital functions 
of a unicellular organism. All goes on as usual, only with 
greater chemical complexity, since all the different processes 
have but a unit-mass of protoplasm in which they occur. 
The physiology 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 globular 
quiescent cell, they change in form, put forth growths of 
various kinds, then become quiescent again and give rise to 
new cells by subdivision 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 
I 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 unconscious, 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 them 
suppose more than some " force," and force is a cause of 
motion in matter, not a cause of organisation. What we 
must assume in this case is not merely a force, but some 
agency which can and does so apply, and direct, and guide, 
and co-ordinate a great variety of forces — mechanical, 
chemical, and vital — so as to build up that infinitely com- 

z 



338 



THE WORLD OF LIFE 



CHAP. 



■ 



plex machine, the living organism, which is not only self- 
repairing during the normal period of existence, but self- 
renewing, self-multiplying, self-adapting to its ever-changing 
environment, so as to be, potentially, everlasting. To do 
all this, I submit, neither " life " nor " vital force " nor the 
* unconscious " cell-soul " are adequate explanations. What 
we absolutely require and must postulate is, a Mind far 
higher, greater, more powerful than any of the fragmentary 
minds we see around us — a Mind not only adequate to 
direct and regulate all the forces at work in living 
organisms, but which is itself the source of all those forces 
and energies, as well as of the more fundamental forces 
of the whole material universe. 

The necessity for some such far-reaching power and 
directive agency will be even more apparent when we con- 
sider the beautiful series of changes which occur in every 
germ-cell of the higher animals (Metazoa) at the commence- 
ment of growth into the perfect form, as detected by means 
of a long series of observations by many embryologists, with 
all the modern appliances of microscopic research, and 
summarised in Professor A. Weismann's interesting volume 
on The Germ-Plasm. 

I will first quote a general description of such a cell 
from Professor Lloyd Morgan's Animal Life and Intelligence, 
and then give the further details as shown in the plate of 
diagrams from Weismann's book. (Fig. 110.) 

" The external surface of a cell is (usually) bounded by a film or 
membrane. Within this membrane the substance of the cell is 
made up of a network of very delicate fibres (the plasmogen), en- 
closing a more fluid material (the plasm) ; and this network seems 
to be the essential living substance. In the midst of the cell is a 
small round or oval body, called the nucleus, which is surrounded 
by a very delicate membrane. In this nucleus there is also a 
network of delicate plasmogen fibres enclosing a more fluid plasm 
material. At certain times the network takes the form of a coiled 
filament or set of filaments, and these arrange themselves in the 
form of rosettes and stars. In the meshwork of the net, as in the 
coils of the filament, there may be one or more small bodies 
(nucleoli), which probably have some special significance in the 
life of the cell." 1 

1 Animal Life and Intelligence, p. 10. 



pa 



I 









xvn MYSTERY OF THE CELL 339 

The accompanying series of diagrams from Professor 
Weismann's book already referred to are intended to show 
the essential features of what takes place in a cell previous 
to division, the detailed fibrous structure of the plasma 
being omitted for the sake of clearness. It must be under- 
stood, however, that much of what is described in the cells 
is quite invisible even in the highest powers of the best 
microscopes, owing to the fact that almost all the parts — the 
fibrous network and granules in the plasma, as well as the 
network in the nucleus — are transparent, and only become 
visible by the use of various chemical reagents and dyes, 
which stain some parts more than others and thus render 
them visible. The parts of the nucleus which are thus 
coloured and rendered visible are termed chromosomes or 
chromatin. I will now quote Weismann's description of 
what happens in such a cell. (Fig. i 10, p. 343.) 

" When the nucleus is going to divide, the chromatin granules, 
which till then were scattered, become arranged in a line and form 
a long thread which extends through the nucleus in an irregular 
spiral (Fig. no A), and then divides into portions of fairly equal 
length (the chro?noso?7ies). These have at first the form of long 
bands or loops, but afterwards become shortened, thus giving rise 
to short loops (B), or else to straight rods or rounded granules. With 
certain exceptions the number of chromosomes which arise in this 
way is constant for each species of plant or animal, and also for 
successive series of cells. 

" By the time the process has reached this stage a special 
mechanism appears, which has till now remained concealed in the 
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 



340 THE WORLD OF LIFE chap. 

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 consider 
as a spherical body." 

Now 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 chromatin- 
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 farther 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 obscurity of the cell-substance, only to become 
active again at the next cell-division. Each separated half of the 
nucleus now constitutes a daughter - nucleus, in which it (the 
chromatin) immediately breaks up, and becomes scattered in the 
form of minute granules in the 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 Roux 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 respect of the different qualities which must be contained 
in it. So complicated an apparatus would have been unnecessary 
for the quantitative division only. If, 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 hypo- 
thesis any longer." ] 

1 The Germ- Plasm, p. 29. 



MYSTERY OF THE CELL 341 

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 develop- 
ment, which is effected by 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 passage : 

" Even the two first daughter-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 conclusion 
is inevitable that the chromatin determining these hereditary tend- 
encies 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 which the male and female elements are com- 
bined, 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 pro- 
duction, in all -future generations, of males and females in 
nearly equal proportions. He also shows that there is a 
special provision for the production 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 fertilisa- 
tion and cell-division. 1 

1 The reader will see that the diagrams referred to in Weismann's statements, 
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 



342 THE WORLD OF LIFE 

In Professor J. Arthur Thomson's most valuable and 
illuminating work on Heredity, in which he impartially 
expounds the theories and discoveries of all the great 
physiological 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 Professor Thomson's very short summary 
of it, giving an explanation of Weismann's special ter- 
minology. Weismann's statement 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 and different kinds of primary constituents, that is, 
of groups of vital units equipped with the forces of life, and capable 
of interposing actively and in a specific manner, but also capable 
of remaining latent in a passive state until they are affected by a 
liberating stimulus, and on this account able to interpose success- 
fully 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." l 

And Professor J. A. Thomson's Summary of Weis- 
mann'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- i 
somes or idants (Fig. no, 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 biophors, 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 

development of cells up to the first cell-division. The small letters (jd) are not I 
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 summary of Weismann's theory at p. 20. 

1 The Evolution Theory, trans, by J. A. Thomson, 1904, vol. i. p. 402. 






XVII 



MYSTERY OF THE CELL 



343 



dkr. 






-Jd> 



S Fig. iio. 

Diagram of Nuclear Division. 

A. Cell with nucleus («) and centro- 
somes (cs) preparatory to division. 
The chromatin hasbecome thickened 
so as to form a spiral thread (chr). 

B. The nuclear membrane has dis- 
appeared. Delicate threads radiate 
from the chromosomes, and form the 
"nuclear spindle," in the equator 
of which eight chromosomes or 
nuclear loops (ckr=Jd) are ar- 
ranged ; 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 chromosomes 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.) 




344 THE WORLD OF LIFE 

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 without taking for granted the essential 
phenomena of life — nutrition, assimilation, and growth ; and 
these are admitted to be to this day quite unexplainable. 

But the very first step of this process of growth — the 
division of the germ-cells, as described by Weismann himself 
and illustrated by his diagrams — is, as he himself almost 
admits, 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 adaptation 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 works, in 
those of Professor Thomson, of Max Verworn, or in such 
general works as Parker and Haswell's Text-Book of Zoology, 
the more hopelessly inadequate do we find the claims of 
Haeckel, Verworn, and their school to having made any 
approach whatever to a solution of " the riddle of the uni- 
verse," 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 
phenomena 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 Natural History of Plants, already- 
quoted, he gives the following short description of cell- 
division : 

" When 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. These 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 the 



MYSTERY OF THE CELL 345 

nucleus — a partition wall of cellulose is interposed in the gap, and 
from a single cell we have now produced a pair of cells " (vol. i. 
p. 43). 

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 vege- 
table 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. Kerner'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 
structures 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 different 
operations in the same protoplasm without any change in the 
external stimuli ; the thorough use made of external advantages ; 
the resistance to injurious influences ; the avoidance or encompass- 
ing of insuperable obstacles; the punctuality with which all the 



346 THE WORLD OF LIFE 

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 operations 
requisite for growth, nutrition, renovation, and multiplication is 
liable to be lost. We call the loss of this power the death of the 
protoplasm" (vol. i. p. 51). 

Growth by 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, which are the 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 
unintelligible to some of my readers, I will now give- a very 
short statement of the process with a few illustrations, and 
remarks as to what 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 budding, where the flower-bud 
which contains a germ-cell, when inserted in the bark of a 
different variety, and sometimes a different species of plant, 
reproduces 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 
nourishment. 

Again, Professor Boveri deprived an egg of a species of 
sea-urchin (Echinus microtuberculatus) of its nucleus, and then 
fertilised the egg with the spermatozoa of another species 
(SphcErcchinus granularis). The egg so treated developed 
larvae 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 its parental 
characters. A similar illustration, at a later period of life, is 
that of an infant which 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 the seat of heredity and 
development. What is it that gives it this power? What 



MYSTERY OF THE CELL 347 

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 
millionfold complex substance called protoplasm. It is 
also mainly living protoplasm. What power gave it life ? 
It is also (in its essential part, the nucleus) already highly 
differentiated — it is organised protoplasm. What power 
organised it ? It is a liquid or semi-liquid substance with 
slight cohesion ; it gradually forms a cell, which divides and 
subdivides, 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 immense 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 combinations chemically, and new structures 
mechanically ? — combinations 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 diverging 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," " deter- 
minants," etc., which actually do build up the living body 
of each organism in a prescribed and unchangeable sequence 
of events. But this orderly process is quite unintelligible 
without some directive organising power constantly at work 
in or upon every chemical atom or physical molecule 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 the fabric of the living, moving, and, in the case of 
animals, sensitive creation. 

I will conclude this short sketch of cell-life and its 



348 THE WORLD OF LIFE chap. 

mystery, with a picturesque account of one striking example 
in the animal world, from Professor Lloyd Morgan's illumin- 
ating volume. 

"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, fine, thick-set hair, and technically termed 
1 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 busy living cells is at work beneath that velvet 
surface, building the bony antlers, preparing for the battles of 
autumn. Each minute cell knows its work, and does it for the 
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 its 
work, having added its special morsel to the fabric of the antler, it 
remains imbedded and immured, buried beneath the bone products 
of its successors or descendants. No hive of bees is busier or more 
replete with active life than the antler of a stag as it grows beneath 
the soft warm velvet. And thus are built up in the course of a 
few weeks those splendid ' beams ' with their • tynes ' and ' snags,' 
which, in the case of the wapiti, even in the confinement of the 
Zoological Gardens, may reach a weight of thirty-two pounds, and 
which, in the freedom of the Rocky Mountains, may reach such a 
size that a man may walk without stooping through the archway 
made by setting up upon their points the shed antlers." 

In the eastern European forests the horns of the red 
deer reach a weight of 74 pounds, while in the recently 
extinct Irish elk the large, broadly palmated horns some- 
times reached an expanse of 1 1 feet. These remarkable 
weapons were developed both for combats between the males 
and as a means of protecting the females and young from 
enemies. As organic outgrowths 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 carry 
out the work with such wonderful precision every year, they 
are equally striking. The blood, we know, furnishes the 
materials for every tissue in the body ; but here a large 



hvii 



lie 

x 

\ 



MYSTERY OF THE CELL 349 

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-Problem 

The very short account I have now given of what is 
known of the essential nature, the complex structure, and 
the altogether 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, convince the reader that the persistent 
attempts made by Haeckel and Verworn to minimise their 
marvellous powers as mere results of their complex chemical 
constitution, are wholly unavailing. They are mere verbal 
assertions which prove nothing ; while they afford no 
enlightenment whatever 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 strange phenomena of cell-life in the Protozoa, and of 
cell-division in the higher animals and plants, seem to think 
anything about the hidden causes and forces at work. They 
are so intensely interested in their discoveries, and in 
following out the various changes in all their ramifications, 
that they have no time and little inclination to do more than 
add continually to their knowledge of the facts. And if 
one attempts to read through any good text-book such as 
Parker and Haswell'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 structure of more than a 
very small number of the known forms. Hence very few of 
the writers of such books express any opinion on those 
fundamental problems which Haeckel and his followers 
declare to have been solved by them. All questions of 
antecedent purpose, of design in the course of development, 



350 THE WORLD OF LIFE 

or of any organising, directive, or creative mind as the 
fundamental cause of life and organisation, are altogether 
ignored, or, if referred to, are usually discussed as altogether 
unscientific 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 comprehensive view of the vast world of life as it is 
spread out before us, and also of that earlier world which goes 
back, and ever farther back, into the dim past among the 
relics of preceding forms of life, tracing all living things to 
more generalised 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 or 
are represented only by rudimentary forms, often of types 
quite unknown to us ; we meet with ever greater and greater 
difficulties in dispensing with a guiding purpose and an 
immanent creative power. 

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 expense, — 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 better adapted to the wants, 
the material progress, the higher enjoyments of mankind. 



XVII 



MYSTERY OF THE CELL 351 



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 con- 
sidering ; and every single individual of the myriads of 
millions which have ever lived upon the earth have each 
begun to be developed from a similar but not identical 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 these cells and all 
their marvellous 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 " ! 

T//e 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 idea that you can get over 
the difficulty of requiring any supreme mind, any author of 
the cosmos, by assuming that it had no beginning — that it 
has existed, with all its forces, energies, and laws, from all 
eternity, and that it will continue to exist for all eternity. 

I have already quoted Haeckel 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 
Universe, in The Academy (March 25, 1905), after discussing 
the theory of dissipation of energy, the infinity of the 
universe, 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 " universe " 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 " universe " is taken by Haeckel and his school 
to mean the material universe, and to definitely exclude 
spirit and God. 

A great modern physicist, Professor Svante Arrhenius, 



352 THE WORLD OF LIFE 

in the preface to his recent work, Worlds in the Making, 
concludes thus : 

" My guiding principles in this exposition of cosmogonic 
problems has been the conviction that the Universe in its essence 
has always been what it is now. Matter, energy, and life have only 
varied as to shape and position in space." 

This will be taken to mean, and I presume does mean, 
" matter " and " life " as we know them on the earth, and to 
exclude, as Haeckel does definitely, spirit and deity. The 
general conception of all these writers seems to be, that it is 
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 
intelligent power beyond what we see. 

Now the idea, that positing eternity for matter and for 
organised life, and for all the forces of nature, overcomes 
difficulties 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 when 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 conditions 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 



tot 



MYSTERY OF THE CELL 353 

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 would be gods. And as you 
cannot diminish eternity, then long ages before the first 
rudiment of life appeared upon the earth, long before all the 
suns we see had become suns, the infinite development had 
been at work and must have produced gods of infinite 
degrees of power, any one of whom would presumably 
be quite capable of starting such a solar system as ours, 
or one immensely larger and better, and of so determining 
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, now, 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 infinite 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 ? 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 directive 
agencies which they imply, and without which none of them 
could for a moment exist, all are to be accounted for and 

2 A 



354 THE WORLD OF LIFE chap, xvn 

explained by the one illogical assumption, their eternity ; 
the one complete misnomer, monism ; the one alleged funda- 
mental law which explains nothing, the " law of substance." 
It will be seen that this alleged explanation — the 
eternal material universe — does not touch the necessity, 
becoming 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 I have 
sufficiently shown that without this, life, as we know it, is 
altogether unthinkable. No " eternal " existence of matter 
will make this in the remotest degree imaginable. It is this 
difficulty which the " monists " and the " eternalists " of the 
Haeckel and Verworn type absolutely shirk, putting us off 
with the wildest and most contradictory 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 with 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 subject 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 the greatchemical complex- 
ity 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 thousand 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 con- 
stituents 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, ten 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 
n alcohol ; while starch is only soluble in warm water. 
These differences are supposed to be due to the different 

355 



356 THE WORLD OF LIFE 

arrangement of the atoms, and to their being combined and 
recombined in different ways ; and as the more atoms are 
used the possible complexity of these arrangements becomes 
greater, the vast numbers and marvellous diversity of the 
organic compounds becomes to some extent intelligible. 
Professor Kerner, referring to the three substances just 
mentioned, 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 
together 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 

I I 

C N 

I I 

c c 

H— C (\ C— H H— C /\ C— H 

H— C I I C— H H— C I I C— H 

c c 

H. 4 

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." 

Here only three elements are combined, and in identical 



ilaminj 



t 



xvni THE ELEMENTS AND LIFE 357 

proportions. We can imagine, therefore, what endless 
diversities arise when to these are added any of nine other 
elements, and these in varying proportions, as well as being 
grouped 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 
comparatively little attention, yet it is really a marvel and a 
mystery 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 believed 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 mechanical, 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 farther 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 building 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 small 
number of these (less than one-fourth) seem to play any 
important part either in the structure of the earth as a planet, 
or in the constitution of the organised beings 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 
which are essential to their continued 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 



358 



THE WORLD OF LIFE 



CHAP. 



respectively of the earth -mass. Then follow calcium, 
magnesium, sodium, and potassium, 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 atmo- 
sphere and the oceans of the globe, which by their purely 
physical action on climate, and in causing perpetual changes 
on the earth's surface, have rendered the development of the 
organic world possible. 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 specific gravity, 
and thus existing (perhaps exclusively) near the earth's 
surface, comparatively little of them was needed. 



List of the More Important Elements 



Elements in Protoplasm in Order of 
their Abundance [approximately). 


Elements in the Earth in Order 0/ their 
Quantity {approximately). 

Per cent. 


i. Hydrogen 
2 . Carbon 






I. 

2. 


Oxygen 

Silicon 


• 47 

• 25 


3. Oxygen 

4. Nitrogen 

5. Sulphur 

6. Iron 

7 . Phosphorus 

8. Chlorine 






3- 
4- 

5- 
6. 

7- 
8. 


Aluminium 
Iron 

Calcium . 
Magnesium 
Sodium . 
Potassium 


8 
7 
4 
3 

• 2-5 

• 2-5 


9. Sodium 

10. Potassium 

11. Calcium 






9- 
10. 


Hydrogen 
Nitrogen . 
All others 


.(?)CVI 

• (?)o-i 
. (?) o-8 


12. Magnesium 










100 


The two elements 


in 


italics — 


Silicon and Aluminium- 


—although 



forming a large proportion of the earth's substance, are not essential 
constituents of protoplasm, 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 



xviii THE ELEMENTS AND LIFE 359 

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 italicised 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 bring about all the 
essential features of our earth as we 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 mercury. 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 the vegetable or animal kingdoms, they 
have yet been of very great 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 commerce ; while the 
facility with which they could be worked and polished called 
forth the highest powers of the artist and craftsman in the 
making of ornaments, coins, drinking-vessels, etc., many of 
which have come down to us 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. 



360 THE WORLD OF LIFE 



CHAP. 



Each of the seven metals (and a few others now in 
common use) has very special qualities which renders it use- 
ful 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 totally 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 existed on the earth for so many 
millions of years for no apparent or possible use ; but 
becoming so supremely useful when Man appeared and 
began to rise towards civilisation ? 

But an even more striking case is that of the substances 
which in certain combinations produce glass. Sir Henry 
Roscoe states that silicates of the alkali metals, sodium and 
potassium, 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 not soluble either in water or acids, and 
which, when fused forms glass, a perfectly transparent 
solid, not crystallised but easily cut and polished, 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 change- 
able climates cannot be over-estimated. Without its use in 
bottles, tubes, etc., chemistry could hardly exist ; while 
astronomy could not have advanced beyond the stage to 
which it had been brought by Copernicus, Tycho Brahe, 
and Kepler. It rendered possible the microscope, the 
telescope, and the spectroscope, three instruments without 
which neither the starry heavens 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 



xviii THE ELEMENTS AND LIFE 361 

rarest substances in nature — radium — and its extraordinary- 
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 develop- 
ment of life upon it ; but the most obvious result of its 
discovery seems to be the new light it throws on the nature 
of matter, on the constitution 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 
useless substances in the earth's crust ; the existence in toler- 
able 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 specially combined, produce a substance without 
which modern science in almost all its branches would have 
been impossible, we are brought 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 forms a part) 
was constituted 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 adequate 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 diffi- 
culties. A beginning in time for all finite things is thus 
demonstrable ; but a beginning implies an antecedent cause, 
and it is impossible to conceive of that cause as other than 
an all-pervading mind. 

1 While this chapter is being written I see it announced that two of the 
rarest of the elements, lanthanium and neodynium, have been found to pro- 
vide (through some of their compounds) light-filters, which increase the effici- 
ency of the spectroscope in the study of the planetary atmospheres, and may thus 
be the means of still further extending our knowledge of the universe. 






362 THE WORLD OF LIFE chap. 

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 uncombined on the earth except as a product of vege- 
tation. 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 meteorites, 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 
which it exists in the sun and comets, whether as carbon- 
vapour or a hydrocarbon. But the most interesting point 
for us is that it exists as a constituent of our atmosphere, 
of which carbon-dioxide forms about 25 1 00 th part, equal to 
about 7o*oo th part 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 extract the carbon from 
the gas, and there is no other means known by which this 
can be done at ordinary temperatures. The chemist has to 
use the electric spark, or very high temperatures, to perform 
what is done by the green leaves at the ordinary tem- 
peratures in which we live. 

The reverse operation of combining carbon with other 
elements 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 which 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 follow in order of difficulty of com- 
bustion coke, anthracite, black-lead, and the diamond." The 



xviii THE ELEMENTS AND LIFE 363 

two latter withstand all temperatures, 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-conductor. 

Carbon unites chemically with almost all the other 
elements, either directly or by the intervention of some of 
the gases. It also possesses, as Sir Henry Roscoe says : " A 
fundamental and distinctive quality. This consists in the 
power which this element possesses, in a much higher degree 
than any of the others, of uniting with itself to form com- 
plicated compounds, containing an aggregation of carbon- 
atoms united with either oxygen, hydrogen, nitrogen, or 
several of these, bound together to form a distinct chemical 
whole." 

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 
hydrogen, nitrogen, and oxygen, together with a small 
quantity (about I per cent) of sulphur, it forms the whole 
group of 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 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 decomposition of the most elaborate albuminoid 
compounds of carbon — are the sole and the mechanical 
causes of the specific phenomena of movement, which dis- 
tinguish organic from inorganic 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 
quantity exists in the various limestone rocks, consisting of 



364 THE WORLD OF LIFE chap. 

carbonate of lime (CaC0 3 ). 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 lime- 
stone are, therefore, 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 altogether remarkable and exceptional properties 
of carbon are fully recognised by modern chemists, as well 
shown by Professor H. E. Armstrong's statements in his 
Presidential Address to the British Association in 1 909 : 

"The central luminary of our system, let me insist, is the 
element 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 farther on he says : 

" Our present conception is, that the carbon atom has tetrahedral 
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 altogether 
astounding." 

And again : 






xviii THE ELEMENTS AND LIFE 365 

" It would seem that carbon has properties which are altogether 
special ; the influence which it exerts upon other elements in 
depriving 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 substances adapted for man's use and enjoyment, 
and especially to serve the purposes of his ever-advancing 
research into the secrets of the universe. 

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 qualities are singularly unlike those of its com- 
ponents, oxygen 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 civilised 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 
becomes 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 problems." One of the facts that seem to be 
now generally accepted is, that water is not the simple 
compound, H 2 0, it is usually held to be, but is really a 
compound of three hydrols, H 2 being gaseous water, 



366 THE WORLD OF LIFE 



CHAP. 



iiin 



(H.,0) 3 being ice, while liquid water is a mixture of these or 
(H 2 0) 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." 

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 sought in its own special and peculiar 
properties." 

Here again we find that the most common and familiar 
of the objects around us, and which we are accustomed to 
look 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 freezing-point. If this curious anomaly did not 
exist the coldest water would always be at the bottom, and 
would freeze there ; and thus many lakes and rivers during 
a hard winter would become solid ice, which the succeeding 
summer might not be able to melt. Sir Henry Roscoe 
says : 

" If it were not for this apparently unimportant property our 
climate would be perfectly Arctic, and Europe would in all 
probability be as uninhabitable as Melville Island." 1 

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 Universe. I will only mention here, that in those 
chapters I have pointed out the probable origin of the great 

1 Elementary Chemistry, p. 38. 






xviii THE ELEMENTS AND LIFE 367 

oceanic basins ; the proofs of their permanence throughout 
all geological time ; the probable causes of that permanence ; 
the necessity of such permanence to preserve the continuity 
of life-development, not only on the earth as a whole, but on 
each of the great continents ; and, lastly, how all these 
phenomena have combined to secure that general uniformity 
of climatic conditions throughout the whole period of the 
existence of terrestrial life which was essential to its full 
and continuous development. There is, I believe, no more 
curious and important series of phenomena connected 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 yet some further relations of water to life 
which may be here briefly noticed. Among the various 
agencies 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 work 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 overlap, as it were, 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 
decomposed by rain, then fractured by the irresistible force 
of ice-formation. On a large scale in polar regions, and 






368 THE WORLD OF LIFE chap, xvm 

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 miles in thickness, grind out deep 
valleys and lake-basins before 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 
infinite variety of contour of the land surface — level plains, 
gentle slopes, beautifully rounded downs, wave-like undula- 
tions, valleys 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 constantly varying scene of beauty — a 
very garden 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 might thus have been in a state not very 
dissimilar from that in which the moon appears to be ; not 
perhaps without a considerable amount of life, but with little 
of its variety, and with hardly any of that exquisite charm 
of contour and vegetation which we are now only beginning 
to appreciate and to enjoy. 









CHAPTER 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 
contemplation 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 when 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 de- 
liberate killing of a fellow-man the greatest of all crimes. 
The idea, therefore, that the whole system of nature from 
the remotest eons of the past — from the very first appear- 
ance of life upon the earth — has been founded upon 
destruction of life, on the daily and hourly slaughter of 
myriads of innocent and often beautiful living things, in 
order to support the lives of other creatures, which others 
are specially adapted to destroy them, and are endowed 
with all kinds of weapons in order that they may the more 
certainly capture and devour their victims, — all this is so 
utterly abhorrent to us that we cannot reconcile it with an 

369 2 B 



370 THE WORLD OF LIFE chap. 

author of the universe who is at once all-wise, all-powerful, 
and all-good. The consideration of these facts has been a 
mystery to the religious, and has undoubtedly aided in the 
production of that widespread pessimism which exists 
to-day ; while it has confirmed the materialist, and great 
numbers of students of science, in the rejection of any 
supreme intelligence as having created or designed a 
universe which, being founded on cruelty and destruction, 
they believe to be immoral. 

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 production 
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 healthy, 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. Be- 
fore dealing with the whole subject from the standpoint of 
evolution, I will quote the opinions of two eminent biologists, 
as showing how the matter has impressed even thoughtful 
and instructed writers. Professor J. Arthur Thomson (of 
Aberdeen University), when reviewing my Darwinism in The 
Theological Review, said : 

"Tone it down as you will, the fact remains that Darwinism 
regards animals as going upstairs, in a struggle for individual ends, 
often on the corpses cf their fellows, often by a blood-and-iron com- 
petition, often by a strange mixture of blood and cunning, in which 
each looks out for himself and extinction besets the hindmost. We 
are not interested in any philosophical justification of this natural 
or unnatural method until we are sure that it is a fact." 



xix IS NATURE CRUEL? 371 

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 devoured by 
carnivores " ; of the carnivores and herbivores alike as 
being " subject to all the miseries incidental 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 thousands of times 
a minute, were our ears sharp 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 what we call 
benevolence. 1 Such a strong opinion, from such an authority, 
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 with 
the principles 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 re- 
peated 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 result whatever, than by 
another belief, which admits the same amount of pain into 
one world only, and for a limited period, while whatever 
pain there is only exists for the grand purpose of developing 
a race of spiritual beings, who may thereafter live without 
physical pain — also for all eternity ! To put it shortly — 

1 The Nineteenth Century, February 1888, pp. 162-163. 



372 THE WORLD OF LIFE chap. 

they prefer the conception of a universe in which pain exists 
perpetually and uselessly, to one in which the pain is strictly 
limited, while its beneficial results are eternal \ 

None of these writers, however, nor, so far as I know, 
any evolutionist, has ever gone to the root of the problem, 
by considering 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 sub- 
ordinated to the law of utility ; and therefore never developed 
beyond what was actually 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 con- 
sider 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 
insignificant when compared with those of the lowest forms 
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 -j-ho mcn l° n g) anc * lis 
being very easily procured. This species multiplies by 
division about twice in three days, and has been kept under 
observation thus multiplying for more than ioo generations. 
Now it is not very difficult to calculate what quantity of 
Paramecia would be produced in any given number of 
generations, and what space they would occupy. No non- . 
mathematical person can imagine or will believe the result. 
It is, that if the conditions were such (as regards space, 
food, etc.) that the Paramecium could go on increasing for 
350 generations, that is to say, for about two years, the 
produce would be sufficient in bulk to occupy a sphere 
larger than the known universe ! 

Now 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 



xix IS NATURE CRUEL? 373 

vast world of life ; and we also see the absolute necessity — 
if it was to continue 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 condi- 
tions in the primeval ocean, the development of new forms 
of life would then proceed more slowly than now. But a 
consideration 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 development of the life of the 
Cambrian period from the earliest one-celled animals. 

We find, then, that the whole system of life-development 
is that of the lower providing food for the higher in ever- 
expanding circles of organic existence. That system has 
succeeded marvellously, even gloriously, inasmuch as it has 
produced, as its final outcome, Man, the one being who can 
appreciate 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, 



374 THE WORLD OF LIFE chap. 

and of mind, this successful outcome is a proof that it is the 
only practicable method, the only method that could succeed. 
For if we assume (with the monists) that it has been through- 
out the outcome of the blind forces of nature — of " the rush 
of atoms and the clash of worlds " — then, as they themselves 
admit, being the outcome of a past eternity of trial and error, 
it could not have been otherwise. If, on the other hand, it is, 
as I urge, the foreordained method of a supreme mind, then 
it must with equal certainty be the best, and almost certainly 
the only 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 knowledge of 
the vastness and mystery of the universe in which he lives ; 
and how any student of any part of that universe can declare, 
as so many do, that there is only a difference of degree 
between himself and the rest of the animal-world, — that, in 
Haeckel's forcible words, " Our own human nature 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," — 
is altogether beyond my comprehension l 

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 conclusions necessarily follow 
from it. And, first, we see that the whole cosmic process is 
based upon fundamental 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 development, 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 

1 See the Riddle of the Universe, chap. xiii. (p. 87, col. 1). 



xix IS NATURE CRUEL? 375 

required for the purposes of their short existence ; that 
anything approaching to what we term " pain " was unknown 
to them. They 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 
provide food for other somewhat higher forms — in fact, to be 
eaten — there was no reason whatever why 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 repro- 
duced their kind. 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 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 devoured ; their enormous powers of increase are 
for this end ; they are subject to no dangerous 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 animals, I think we 
may place almost all aquatic animals up to fishes, all the vast 
hordes of insects, probably all Mollusca and worms ; thus re- 
ducing 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 birds 
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 afterwards ; and as no 



376 THE WORLD OF LIFE chap. 

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 wonderfully adjusted 
to their environments, that, in a state of nature, they can 
hardly suffer at all from what we term accidents. Birds, 
mice, squirrels, and the like, do not get limbs broken by 
falls, as we do. They learn so quickly and certainly not to 
go beyond their powers in climbing, jumping, or flying, that 
they are probably never injured except by rare natural 
causes, such as lightning, hail, forest-fires, etc., or by fighting 
among themselves ; and those who are injured without being 
killed by these 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 rapidity 
with which such wounds heal in a state of nature shows that 
whatever pain exists is not long-continued. 

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 safeguarding 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 dangers which most wild animals have to be 
guarded against ; and no very extreme amount of pain would 
be needed for this purpose, and therefore would 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 contrivances for shedding blood or causing pain 
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 






IS NATURE CRUEL? 377 

weapons exist for the purpose of shedding blood or giving 
pain is wholly illusory. As a matter of fact, their effect is 
wholly beneficent even to the sufferers, inasmuch as they 
tend to the diminution of pain. Their actual purpose is 
always to prevent the escape of captured food — of a wounded 
animal, which would then, indeed, suffer useless pain, since 
it would certainly very soon be captured again and be 
devoured. The canine teeth and retractile claws hold the 
prey securely ; the serpent's fangs paralyse it ; and the wasp'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 wild cat, suffer very little, is, I think, conclusive. 
The suddenness and violence of the seizure, the blow of 
the paw, the 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. 1 

Our whole tendency to transfer otir 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 

1 See a brief discussion of this subject in my Darwinism, pp. 36-40. 



378 THE WORLD OF LIFE 

the solution of a problem which has long puzzled me — why 
man lost his hairy covering, especially from his back, where 
it would be so useful in carrying off rain. He may have 
lost it, gradually, from the time when he first became Man 
— the spiritual being, the " living soul " in a corporeal body, 
in order to render him more sensitive. 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 hourly 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 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. 

His tools continually becoming more and more dangerous, 
and his weapons becoming more and more destructive, were 
alike a danger to him. The scythe and the sickle caused 
accidental wounds, 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 danger, impelling him to the avoidance of wounds 
by skill and dexterity, by the use of padded clothing or of 
flexible armour ; while nature's remedies were sought out 
to heal the less deadly injuries, and thus avoid long suffering 
or permanent disablement. And ever as civilisation went 
on, such dangers increased. 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 machinery 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 



xix IS NATURE CRUEL? 379 

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 
sensibility that we, most illogically, transfer to the animal- 
world in our wholly exaggerated and often quite mistaken 
views as to the cruelty of nature ! 

As a proof of the increased sensibility of the civilised as 
compared with the more savage races, we have the well- 
known 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 away 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. 
He 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 average 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 
insisted 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, 



380 THE WORLD OF LIFE 

and must therefore be proportionate in each species to its 
needs, not beyond those needs. In the lowest animals, whose 
numbers are enormous, whose powers of increase are 
excessive, whose individual lives are measured by hours or 
days, and which exist to be devoured, pain would be almost 
or quite useless, and would therefore not exist. Only as the 
organism increased in complexity, in duration of life, and in 
exposure to danger which might 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 painless ; 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 necessarily 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 argu- 
ment 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-preserv- 
ing variations, qualities, or faculties that have survival value : 
pain is one of the most important of these for us, but it is 



IS NATURE CRUEL? 381 

by no means so important to any other animal. No other 
animal needs the pain -sensations that we need; it is there- 
fore absolutely certain that no other possesses such sensations 
in more than a fractional degree of ours. What that fraction 
is we can only roughly estimate by carefully considering 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 probably 
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 be 
taken as an argument in favour of vivisection. No doubt it 
will ; but that does 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 
suffer 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 pro- 
duce a callousness 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 argument of the uselessness of a large pro- 
portion of the experiments, 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 physio- 
logical students in hundreds of colleges and schools all over 
the world, remains. I myself am thankful to be able to 
believe that even the highest animals below ourselves do 
not feel so acutely as we do ; but that fact does not in any 
way remove my fundamental disgust at vivisection as being ? 
brutalising and immoral. 



382 THE WORLD OF LIFE chap. 

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 pro- 
perty 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 injury even to the patients for whose 
benefit it has been applied. It seems probable, therefore, 
that if these rays had been associated in any perceptible 
degree with the heat and light we receive 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 in- 
cidence of these rays on the body, because living organisms 
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 parasites, by the application of the more ex- 
tended views of evolution I have advocated in the present 
volume. The medical profession appear 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 every 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, because 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 of 
health is the one and only protection we require against all 
kinds of disease ; and that to put any product of disease 



xix IS NATURE CRUEL? 383 

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 argument there 
can be nothing in nature which is not useful, and, in a broad 
sense, essential to the whole scheme of the life -world. On 
this principle the purpose and use of all parasitic diseases, 
including those caused by pathogenic germs, is 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 requiring food and occupying space needed 
by the more fit. Their life is thus shortened, and a linger- 
ing and unenjoyable existence 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." x 

But in this interesting article the writer elsewhere uses 
language implying that even the healthy require rendering 
"immune" against all zymotic diseases. It is that 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 with vivisection itself. 

It will be said that quite healthy persons die of these 
diseases, 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 suffer 
most from these diseases is strongly against the truth of the 
statement. No doubt savage races often suffer dreadfully 
from these diseases ; but savages are no more universally 
healthy than the more civilised, 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 safe- 
guards against disease ; and that securing the conditions for 

1 Parasitism and Natural Selection, by R. G. Eccles, M.D., Brooklyn, N.Y., 
U.S.A. 



384 THE WORLD OF LIFE chap, xix 

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 unnecessary weight to those appear- 
ances 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 ?iecessity 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 much 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 problem has 
never been considered from this point of view, the only 
one for the evolutionist to adopt. Hence the ludicrously 
exaggerated view adopted by men of such eminence and 
usually of such calm judgment as Huxley — a view almost as 
far removed from fact or science as the purely imaginary 
and humanitarian dogma of the poet : 

" The poor beetle, that we tread upon, 
In corporal sufferance finds 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 had 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 relation to man as an intellec- 
tual and moral being, thus summarising 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-Form. 

Modern research shows us that the immense diversity of 
life-forms we now find upon the earth is due to two 
kinds of causes, the one immediate, the other remote. The 

385 2 C 



386 THE WORLD OF LIFE chap. 

immediate cause is (as I have endeavoured to show here), 
the slow but continuous changes of the earth's surface as 
regards contour, altitude, climate, and distribution of land 
and water, which successively 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 process has worked 
throughout the geological ages, the world's surface ever 
becoming more complex through the action of the lowering 
and elevating causes on a crust which at each successive 
epoch has itself become more complex. This has always 
resulted in a more varied and generally higher type of 
vegetation, 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 marvellous living, moving, self-supporting, and 
self - reproducing structures, must be many million times 
greater than those which conceived and executed the modern 
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 complexity of structure 
during the last century. But if we take account of the 



THE PURPOSE OF DIVERSITY 387 

advance of chemical science, the knowledge that has been 
obtained of the inner nature of the best-known older 
elements, the wonderfully complex laws of their combinations, 
and the immense variety of their known compounds, our 
ever-increasing knowledge of the complexity of matter will 
be very much greater. 

During the early part of the nineteenth century, the 
old idea of atoms as being indivisible, incompressible, and 
indestructible particles, almost universally prevailed. They 
were usually supposed to be spherical in form, and to be 
the seat 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 in 
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 electric and magnetic forces 
seemed capable of explaining much. 

But, decade after decade, fresh discoveries were made ; 
chemical 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 intelligible than it had ever seemed to us 
before. 1 

1 The progress of modern chemistry well shows this increasing complexity 
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. But it is found that many 
other elements have similar properties, especially silicon, phosphorus, arsenic, 
antimony, sulphur, oxygen, and several others. This curious property is termed 
allotropy ; and it seems somewhat analogous to that property of many compound 
substances termed isomerism, of which two striking examples were given at the 
beginning of the last chapter. Another modern branch of chemistry is the study 
of the relation of crystallised substances to polarised light, which reveals many 
new and strange properties of identical compounds, and is termed Stereo- 
chemistry. 

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 



388 THE WORLD OF LIFE 

Returning 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 them- 
selves, the various salts, alkalis, earths, metallic ores, 
precious stones, and crystals, which have a definite 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 the surface by volcanoes and hot springs, renders 
it probable that very few either of the elements or com- 
pounds remain unknown. 

The skill of the chemist, however, has led to the pro- 
duction of a much greater number of stable chemical 
compounds than occur in nature. These are used in 

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 complexity 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 Froc. 
Roy. Soc, series A, vol. 84, p. 84), the author says : "By the kindness of Dr. 
Silberrad, I have had an opportunity of experimenting with octamethyltetramino- 
dihydroxyparadixunthylbezonetetracarboxilic acid." 

He then adds : " Previous experiments would lead one to expect the scandium 
salt of this acid to have the composition C 44 H 40 O 14 N 4 Sc 2 . The only scandium 
salt I could form with this acid has the composition C g8 H 7i) 29 N 8 Sc 5 . 



THE PURPOSE OF DIVERSITY 389 

medicine or in the various arts, and their numbers are 
very great. They are usually divided into two classes, the 
inorganic and the organic ; the former being of the same 
nature as those of the great bulk of the mineral species, 
while the latter, called also carbon -compounds, resemble 
the products of living organisms of which carbon is an 
essential part. 

A recent estimate of the known inorganic compounds, 
natural and artificial, by a French chemist is 8000 ; but 
Mr. L. Fletcher, of the British Museum, informs me that 
this number must only be taken as an " irreducible minimum." 
As to organic compounds, I am told by Professor H. E. 
Armstrong, that they have recently been estimated at about 
100,000 ; but he states that the possibilities of forming such 
compounds are infinite, that chemists can make them by the 
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 
possibilities of the elements (or rather of about one-fifth of 
them) to produce the almost endless variety of natural 
products in the vegetable and animal kingdoms. These 
possibilities must depend upon the "properties" of the 
elements ; not only their actual properties as elements, but 
their latent properties through which they not only com- 
bine with each other in a great variety of ways, but, 
by each combination create, as it were, a new substance, 
possessing properties and powers different 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 superficial 



390 THE WORLD OF LIFE chap. 

view of the marvels of " growth " and cell-division in living 
organisms. In the Address already quoted, Prof. H. E. Arm- 
strong 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 
grow ; of the protoplasm which is the substance of the cells ; 
of the elements of which protoplasm consists ; of the mole- 
cules of those elements ; and finally of the atoms whose 
combination forms the separate and totally distinct ele- 
mentary molecules. And at each step farther back we are 
as far off as ever from comprehending 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 revolving electrons or corpuscles, held 
together by tremendous forces — the mystery becomes deeper 
still, and we find it quite hopeless to realise what is the 
nature of the controlling power and mind, which out of such 
unimaginable entities has built up the vast material universe 
of suns and systems of which our earth forms a fractional 
part, together with that even more complex world of life of 
which we ourselves are the outcome. 



! 



THE PURPOSE OF DIVERSITY 391 

The overwhelming complexity and diversity 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 nebulae, of light and 
motion, are as they are, firstly, for the development of life 
culminating in man ; secondly, as a vast school-house for 
the higher education of the human race in preparation 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 served the purpose of aiding the gradual 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 unknown worlds with 
which he was encompassed — those of the almost infinitely 
great and of the almost infinitely little ; but both alike 
attractive and grand in their revelations ; both offering ever- 
fresh vistas of unfathomed 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 
beliefs of bygone ages. 



392 



THE WORLD OF LIFE 



CHAP. 



A Suggestion as to the Origin of Life 

As it may be expected that I should state what is my own 
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 Darwin'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 without studying or com- 
prehending the steps by 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 readers 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 only my further 
argument will be directed. 

My first point is, that the organising mind which actually 
carries out the development of the life-world need not be 
infinite 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, omni- 
potent God on the other. The apparently gratuitous creation 



THE PURPOSE OF DIVERSITY 393 

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 assumption 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 infinite series 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 
universe {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 inorganic and organic worlds through 
which they have been developed ; and if we further suppose 
(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 which, I quite admit, seem 
to be essential coadjutors in the process of life-development. 

Now 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 
obedience ; I can imagine the supreme, the Infinite being, 
foreseeing and determining the broad outlines of a universe 
which would, 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 primal 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, 



394 THE WORLD OF LIFE 



CHAP. 



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 
Amoeba to Man, with a surplus of a few hundred 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 qualitative 
conditions which such a world must possess ; and the next 
step in the process of what may be well 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 
organisation, 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, with 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 we 
may term organising spirits, who would be charged with 
the duty of so influencing the myriads of cell-souls as to 



xx THE PURPOSE OF DIVERSITY 395 

carry out their part of the work with accuracy and certainty. 
In the power of " thought-transference " or mental impression, 
now generally 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 the cells are rapidly increasing. 

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 worked 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 work (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 variety, beauty, and use for man, when 
the time came for his appearance ; 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 harmony with 
the universal teaching of nature — everywhere 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 
constitution of the universe. The vast whole is therefore 
a manifestation of his power — perhaps of his very self — 



396 THE WORLD OF LIFE 



CHAP. 



but by the agency of his ministering angels through many 
descending grades of intelligence and power. 

Diversity of Human Character 

Many people are disturbed by the now well-established 
fact that the effects of use, of training, or of education, are 
not inherited ; and that though innate mental as well as 
bodily characters vary much through inheritance, these can 
only be developed in special directions by some form of 
selection. There being very little if any effective selection 
of character among civilised people, they therefore fear that 
there can be no continued advance of the race. Quite 
recently I have discussed this question from two points of 
view. By a general glance over the early history of 
civilised man I have shown that there is little if any 
evidence of advance in character or in intellect from the 
earliest times of which we have any record. 1 I had already, 
twenty years ago, shown in some detail 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 necessarily arise 
through elimination of the worst and most degraded 
by an effective and truly natural selection. 2 The following 
passage towards the end of the former article will briefly 
indicate 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 possible when 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, very briefly, how the views 
here sketched out are in perfect harmony with the entire 

1 "Evolution and Character," Fortnightly Review, January i, 1908. 

2 "Human Selection," Fortnightly Review, September 1890. Reprinted 
in Studies, Scientific and Social, 1900, vol. i. p. 509. 



THE PURPOSE OF DIVERSITY 397 

scheme of the life-world. That scheme is shown to be the 
production of an almost infinite diversity in forms of life, 
beautifully co-ordinated for the common good, and for the 
ultimate development and education of an almost equally 
varied humanity. That variety has been assured and 
increased by the rapid development of man — from the 
epoch when he became a living 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 unchecked 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 Retz, 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 
education should be inherited, then men would have been 
continually moulded to certain patterns ; originality would 
have been bred out by the widespread influences of medi- 
ocrity 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 influences 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, we 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 temptations to which they 
were, and still are, so unnecessarily exposed. 

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 



398 THE WORLD OF LIFE chap. 

every spirit has been derived from the Deity, only limited 
by the time at the disposal of each of us. In the spirit- 
world death will not cut short the period of educational 
advancement. The best conditions and opportunities will be 
afforded 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. 1 
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 Royal Arch ! 
Come and join the Past Grand Masters, in the Soul's progressive 

march, 
O thou neophyte of Wisdom ! Come up to the Royal Arch ! ' " 



1 Of the more serious books dealing with the ethics and philosophy of 
spiritualism, I will only direct the reader's attention to two : Spirit Teachings, 
by W. Stainton Moses, M.A. ; and Psychic Philosophy, as the Foundation of a 
Religion of Natural Law, by V. C. Desertes. To such of my readers who wish 
to obtain some knowledge of the higher aspects of modern spiritualism, I strongly 
recommend these two works. As an example of its highest literary achieve- 
ments are many of inspirational poems in Miss Doten's Poems of the Inner Life ; 
while a still higher standard is reached in A Lyric of the Golden Age, by Thomas 
Lake Harris. This is a poem of 400 pages, which for a sustained high level of 
beauty, grandeur, and moral teaching has few if any equals in our language. 



xx THE PURPOSE OF DIVERSITY 399 

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 : 

" 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 
evidences in plant and animal life indicating a prevision and 
definite 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 con- 
ditioned 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 Matter." 
I have here expressed the same views in a more concrete and 
intelligible manner. This " Unknown Reality " is necessarily 
infinite and eternal as well as all-knowing, but not necessarily 
what we may ignorantly mean by " omnipotent " or " benevo- 
lent " in our misinterpretation of what we see around us. I 
have, I hope, cleared away one of these misinterpretations 
and misjudgments in my chapter, Is Nature Cruel ? 



400 THE WORLD OF LIFE chap, xx 

But to claim the Infinite and Eternal Being as the one 
and only direct agent in every detail of the universe 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 higher 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 continuous 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 approximation 
we are now able to formulate as to the deeper, the more 
fundamental causes of matter and force, of life and con- 
sciousness, and of Man himself ; at his best, already " a little 
lower than the angels," and, like them, destined to a per- 
manent progressive existence in a World of Spirit. 



INDEX 



ACIDASPIS 
Acidaspis dujresnoyi, 267 
Adaptation, some aspects of, 131 
Adaptations to drought, 67 ; birds 

and insects, 132; not effected by 

use, 260 ; of plants, animals, and 

man, 305 
sElusaitrus felintis, early reptile, 199 
Agassiz, A., on deposition by 

Mississippi, 178 
Allegory, a physiological, 296 
Allotropy of elements, 387 
Alpine floras not exceptionally rich, 

35. 37, 80 
Amblypoda, a sub-order of Ungulata, 

219 
America, flora of tropical, 55 
American bison, former enormous 

population of, 115 
Ammonites, eccentric forms of, 267 
Amceba, description of, 335 
Amphibia, earliest forms of, 195 
Ancyloceras matkeronianum, 269 
Andrews, Dr. C. W., discovers 

ancestral forms of elephants in 

Egypt, 228 
Animals, numerical distribution of, 83 ; 

much less sensitive than man, 376 
Anoplotherid.e, ancestral ruminants, 

227 
Anoplotkeriiim commune, skeleton of, 

227 
Antelopes, recognition-marks of, 160 
Archaopteryx macntra, 214; siemensi, 

skull of, 215 
Arctic lands a birds' paradise, 140 
Argyll, Duke of, on humming-birds, 

165 
Armstrong, Professor H. E., on 

importance of carbon, 364 ; on 

directive influences in growth, 390 
Arrhenitjs, Professor, on an eternal 

universe, 352 



birds 
Arsinoitheri it7)i zitteli, skull of, 223 
Astropotheria, extinct ungulates, 

235 

Atlantosaurtis immanis, a huge dino- 
saur, 204 

Atoms, early ideas of, 387 

Australia, extinct mammals of, 239 

Babirusa, tusks of, 275 
Ballota nigra, local distribution of, 14 
Balsams, dyes, oils, etc., variety of, 327 
Bate-Hardy, Mr. W., on arrange- 
ment of identical atoms in carbon 

compounds, 356 
Beccari, Dr., on forest flora of 

Borneo, 47 ; on first and second 

grade species, 96 
Beetle mimicking wasp, 157 
Beetles, number known, 85 ; peculiar 

British, 125 
Being, grades of between us and 

Deity, 393 
Bird, earliest known, 287 
Bird and insect co- adaptation, 132 ; 

teachings of, 152 
Bird's wing, the ideal aimed at in, 

288 ; a feather, detailed structure of, 

289 ; its annual regrowth, 291 
BiRD-CpLOUR, extreme diversity not of 

survival value to them, 319 
Bird-migration, origin of, 148 
Birds, of New Guinea and Borneo, 49 ; 
species of, 86 ; of six geographical 
regions, 89 ; peculiar to Britain, 
125, 126; arrival of, in Arctic 
regions, 140, 142 ; number of species 
in Arctic regions, 145 ; recognition- 
marks of, 162 ; the earliest, 213 ; 
recently extinct, 243 ; loss of teetli 
in modern, 270 
Birds and insects, proofs of organising 
mind, 286 

101 2 D 






402 



BIRDS OF PARADISE 



INDEX 



DARWIN 



Birds of Paradise, new types of, 276 
Bison, former great population of in 

America, 1 1 5 
Bolus, Mr. H., on flora of Cape 

peninsula, 37 ; on orchids of Cape 

peninsula, 38 
Borneo, rich forest flora of, 47 ; birds 

of, 49 
Botanical reserves, advantages of 

small, 75 
Boveri's experiments on echini, 346 
Brain -cavity of Dinocerata very 

small, 223 
Brains of early vertebrates, small, 270 
Brazil, richness of flora of, 70 
Britain, peculiar animals and plants 

of, 125 
British India, flora of, 43 ; chief 

natural orders of, 44 
British plants, numerical distribution 

of, 22, 25 ; of limited range, 24 
Brittan, Mr. L. N., on flora of 

Jamaica, 63 
Brontosaurus excelstts, skeleton of, 205 
Butler, Sir W., on mosquito-swarms, 

135 

Butterflies, recognition by, 167, 

172 

Butterfly, stages of development of, 
301 ; scales on wings of, 301 

Butterfly and caterpillar, diverse 
structure of, 298 

Caltha palustris, wide range of, 1 7 
Cambrian age, first known life of, 192 
Campanula isophylla, small range, 18 
Cape Colony, flora of, 70 
Cape peninsula, rich flora of, 37 
Cape Region, rich flora of, 32, 72 
Carbon, the mystery of, 362 ; proper- 
ties of, 363 ; in the ocean, 364 
Carnivora, early forms of, 224 ; 

extinct South American, 233 
Cavies, numerous extinct, 235 
Celebes, flora of, 51, 79 
Cell, the mystery of, 335 ; character- 
istics of, 337 ; implies an organising 
mind, 338 ; described by Professor 
Lloyd-Morgan, 338; Weismann's 
description of a dividing, 339 ; 
Weismann's statement of its powers, 

342 
Cell-problem, concluding remarks 

on, 349 
Ceratites nodosus, 268 
Ceralosaurus nasuornis, skull of, 206 
Cetiosaurus letdsi from Oxford clay, 204 



Challenger voyage defines area of 
deposition, 177 

Chemical problems of water, 365 ; 
nomenclature, illustration of com- 
plexity of, 388 ;;. 

China and Corea, flora of, 31 

Christianity, gradual rise of a purer, 
280 

Cities, the " wens " of civilisation, 285 

Coal, wide distribution of palaeozoic, 
196 ; prepared atmosphere for higher 
life, 197 

Cobbett, William, on "wens," 285 

Cockerell, on tropical species as com- 
pared with temperate, 97 

Coleoptera, number of British, 84 ; 
number known, 85 

Colour, for concealment, 157 ; ex- 
tremes of, 276 ; of flowers supposed 
to show inedibility, 308 ; purpose of 
in nature, 310; of plants and animals 
in relation to man, 315 ; our sensa- 
tions of, an argument for design, 
322-4 

Colour-sense not identical in birds, 
mammals, and man, 311-12, 317 

Colours of butterflies, uses of, 169 

Colours and ornaments of males, 
how caused, 262 

Compounds, inorganic, number of, 
389 ; number of organic (artificial), 
389 

CONDYLARTHRA, 219 

Conocoiyphe suitzeri, 267 
Continental extensions, appendix 

on, 249 ; great difficulties of, 250-51 
Continents, how built up, 182, 184 
Coryphodon, an early ungulate, 219 
Creators of matter and life not 

necessarily omnipotent, 393 
Creodonta, early carnivores, 224 
Crioceras emerici, 268 
Crookes, Sir W., gives an example 

of complex chemical nomenclature, 

388 
Cruelty of nature, supposed, 369 
Crustacea, early appearance of, 195 

D^dicurus, giant extinct armadillo, 

236 
Darwin on flora of a very small area, 

81 ; on increase of elephant, 114; 

on Porto Santo rabbits, 127 ; on the 

uses of colour to plants, 305 ; on 

cross -fertilisation of flowers, 306 ; 

on war of nature, 370 ; on intelligent 

cause of the universe, 392 



DARWINISM 



INDEX 



FLORAS 



403 



Darwinism, extensions of, 252 
Deane, Mr. H., on flora of Sydney, 

New South Wales, 38 
De Candolle, A., on botanical geo- 
graphy, 17, 21 ; botanical regions 
of, 18 
Definition of life, 3 
Denudation, rate of, measured, 175 
Deposition, area of, 177 
Determinants, meaning of, 272 
Development, reversal of, 230 ; cases 

of extreme, 274 

Diagram of human stature, 108 ; of 

variation of rice -bird, 110; of 

nuclear division, 343; of isomerism, 

356 

Dicynodon lacerticeps, early reptile, 199 

Dimetrodon, extinct reptile from 

Permian of Texas, 200 
Di nocerata, ' ' terrible horned beasts, " 

220 
Dinosauria, 201 
Diplodocus, skull of, 206 
Diplodocus carnegii, skeleton of, 205 
Diprotodon australis, skull of, 240 
Dipterocarps, abundance of in 

Borneo, 47 
Directive agency not explained by 
Darwin's " pan-genesis" nor any other 
theory, 295, 333 ; indications of, 
328 ; at work, 346-7 
Distribution of species result of con- 
tinuous adaptation, 96 
Domestic animals, uses of, 283 
Dresser, Mr. H. E., on birds breed- 
ing in Arctic regions, 144 ; on mos- 
quitoes as food for birds, 146 
Drosera rotiuidifolia, wide range of, 1 7 
Drought, adaptations of plants to, 67 
Dwina river, rich deposits with early 
reptiles, 199 

Earth's surface changes a cause of 
evolution, 173 ; thickness of crust 
of, 179 ; crust floats on melted in- 
terior, 180; effect of cooling and 
contracting, 181 ; surface-motions, 
long persistence of, 184 ; rendered 
habitable by water, 367 
Eccentricity in nature, 276 
Eccles, Dr. R. G., on uses of 

parasites, 383 
Echiims microtiiberculatus , egg of, 346 
Edentata, extinct S. American, 235 
Educational effects, unlimited in the 

spirit-world, 398 
Elements in relation to the life-world, 



355 ; important and unimportant, 

357 ; list of important, 358 ; in 

relation to man, 359 
Elephants, rate of increase of, 114; 

the origin of, 227 ; diagram of 

development of, 229 
Elephas ganesa, enormous tusks of, 

266 ; primigenins, skeleton of, 232 
Eternity as explaining evolution 

fallacious, 351 
European floras in different latitudes, 

29 ; compared, 34 
Evolution, motive power of organic, 

173 

Extensions of Darwinism, 252 
Extinction of pleistocene mammals, 
cause of, 244 

Feathers, marvel and mystery of, 

287 
Female choice, new argument against, 

170 
P'erns, extreme abundance of, in the 

Philippines, 50 
Fishes, peculiar British, 125 ; the 

earliest known, 193 ; types of tails 

of, 194 
Fletcher, Mr. L., on inorganic 

compounds, 389 
Flight of birds and insects compared, 

87 
" Flora Orientalis," species in, 31 

Flora of China, 31 ; of Chile, 32 ; of 
Cape region, 32 ; of tropical Asia, 
42 ; of British India, 43 ; of Malay 
Peninsula, 45 ; of Borneo, 47 ; of 
Indo-China, 48 ; of Malay Islands, 
48 ; of New Guinea, 52 ; of Philip- 
pines, 50; of Celebes, 51, 79; of 
Queensland, 54 ; of tropical Africa, 
54; of Madagascar, 55; of tropical 
America, 54, 55, 59 ; of Brazil, 57 ; 
of Mexico and Central America, 60 ; 
of Jamaica, 63 ; of Trinidad, 63 ; of 
Galapagos Islands, 63 ; of Lagoa 
Santa, 63, 70 ; of Penang, 72 ; of 
Kambangan Islands, 73 ; of Pan- 
gerango, 74 ; of mountains in Japan, 
80 ; of very small areas, 81 

Floras of different regions compared, 
21 ; of counties compared, 25 ; of 
some parishes, 26 ; of small areas, 
26, 71 ; of temperate zones com- 
pared, 28 ; cause of richness of some; 
32 ; warm temperate compared, 33, 
of European small areas, 34 ; of 
mountains and plains compared, 35, 



404 



FLOWERING 



INDEX 



JORDAN 



37, 80 ; extra-European temperate, 
36 

Flowering plants, peculiar British, 
125 

Flowers, abundance of, within Arctic 
circle, 142 

Food of young birds, 132 

Forbes, Mr. H. O., on self-fertilisa- 
tion of orchids, 308 

Forest reserves, advantages of small 
botanical, 75 

Fruits, colour of, 312 

Galapagos, flora of, 63 
Galton's law of heredity, 102 
Gamble, Mr. J. T., on flora of Malay 

Peninsula, 45 
Gardner, on flora of Brazil, 70 ; 

on supposed greater richness of 

mountain floras, 80 
Gatke, Herr, on bird-migration at 

Heligoland, 149 
Geese moulting in Arctic regions, 137 
Gentiana verna, one locality in Britain, 

24 
Geological record, account of, 188 ; 

its three well-marked periods, 189 ; 

the teaching of, 280 
Geology, as influencing evolution, 174 
Germinal selection, 261, 271, 275 
Glass essential for science, 360 
Glyptodon clavipes, skeleton of, 236 
Glyptodontid^e, extinct armadillos, 

235 

Grant Allen on insects and colour of 
flowers, 309 

Grey plover's nest in Arctic regions, 
144 

Griesbach, on Mediterranean flora, 
31 ; on Brazilian flora, 70 

Growth, the nature of, 291 ; by cell- 
division, 292 ; admitted to be in- 
explicable, 344; by cell -division, 
what it implies, 346 

Gunther, Dr., on species of birds, 88 

Haeckel on consciousness, 5 ; on 
human nature, 6 ; matter and ether, 
7,8; on soul-atom unconscious, 333 ; 
his carbon-theory of life, 363 

Hamites rotundas, 269 

Hardy, Mr. W. B., on complexity of 
proteid molecule, 355 

IIartert, Dr., on peculiar British 
birds, 126 

Hayati, Mr., on floras of Japanese 
mountains, 36, 37 



Heat, rate of increase in deep borings, 

179 
Heligoland and migrating birds, 

149 
Hemsley, W. B., on flora of Central 

America, 60 
Heredity a universal fact, 101 ; 

Galton's law of, 102 
Heteroceras emeriti, 268 
Hooker, Sir Joseph, on flora of British 

India, 43 ; on primary floras, 61 ; 

on rich flora of Penang, 72 ; on 

floras of very small areas, 81 
Horns as recognition-marks, 160 
Horses, extinct South American, 233 
Hudson, W. H., on field mice in 

Argentina, 122 
Human character, diversity of, 396 
Hutton, Capt., on recognition-marks, 

165 
Huxley, Professor, on nature and 

origin of life, 8 ; on matter and 

spirit, 9 ; on cruelty of nature, 371 
Hycenodon ententes, skeleton of, 225 
ffyofiotamus brachyrhynchus, skeleton 

of, 226 

Ichthyopterygia, 207 
Ichthyosaurus, paddles of, 20S 
Ichthyosaurus communis, skeleton of, 

207 
Iguanodon bernissartensis, skeleton of, 

201 ; skull of, 202 
Increase in plants and animals, 113 
Indo-China, estimate of flora of, 48 
Inheritance of educational results 

would have checked diversity, 397 
Inorganic substances, variety of, 386 
Inostransevia, huge carnivorous 

reptile, skull of, 200 
Insect life of secondary period, 212 
Insect pests, uses of, 131 
Insects, known species of, 85 ; 
peculiar to Britain, 125; earliest 
known, 195 ; and their metamor- 
phosis, 297 
Insects and birds, co-adaptation of, 

132 
Irish deer, skeleton of, 266 
Isomerism explained, 357 

Jack-rabbit, E. S. Thompson on, 159 
Jamaica, flora of, 63 
Japan, mountain floras of, 36, 37 
Java, rich flora of, 73 
Jordan, Dr. K., on phosphorescent 
colours in lepidoptera, 322 



JUDD 



INDEX 



MIND 



405 



Judd, Professor, on strange forms of 
ammonites, 269 

Kambangan island, rich flora of, 73 
Karoo formation, reptiles of, 198 
Kearton on increase of rabbits, 114 
Kerner, Dr. A., on power of increase 
of plants, 113 ; on the insect enemies 
of flowers, 307 ; on " vital force," 
330 ; on arrangement of atoms in the 
carbon-compounds, 356 
Koorders, Dr., on the flora of 
Celebes, 51, 79 ; on rich floras of 
small areas in Java, 74 

Lagoa Santa, flora of, 63, 70 
Land-shells, peculiar British, 125 
Latitude as influencing floras, 29 
Lemming, periodical migrations of, 

119-22 
Lepidoptera, number of British, 83 ; 
number known, 85 ; peculiar 
British, 125 ; wealth of colour in, 
320-24 
Life, definition of, 3 ; Haeckel on, 
4, 7 ; the cause of organisation, 8 ; 
reactions of animal and plant, 282 ; 
the sole cause of life, 284 ; a sugges- 
tion as to origin of, 392 
Life-development of mesozoic era, 

215 ; conclusion on, 277 
Life-forms, causes of diversity of, 

385 
Life- world, progressive development 

of, 188 
Limestone, progressive increase of, 

217 
Lithospermtun gastoni, narrow range 

of, 18 
Llamas, extinct S. American, 233 
Lloyd-Morgan, statement of theory 

of germinal selection, 271 ; on rapid 

cell-growth, 348 
Lydekker, Mr., on Patagonian mar- 
supials, 224; on affinities of American 

and Australian marsupials, 241 
Lyell, Sir C, on causes of extinction, 

246 
London, how to stop growth of, 285 
Lovvne, Mr. B. T. , on development 

of blow-fly, 299 

Macharodus neogaus, skull of, 266 
Macrauchenia patachonica^ 234 
Macroscaphites ivanii, 269 
Madagascar, flora of, 55 
Maritheriwn lyonsi, skull of, 228 



Malay Islands, flora of, 48 ; insects 

of, 86 
Malay Peninsula, table of chief 

orders of plants, 45 ; characteristic 

plants of, 46 
Mammalia, teachings of pleistocene, 

242 
Mammals, extinct Australian, 239 
Man, the cause of extinction of pleisto- 
cene mammals, 246-9 ; the glory 

and distinction of, 373-4 ; the most 

sensitive of organisms, 377 
Mantell, Dr., discovered extinct 

reptiles in Kent, 201 
Marsh, Professor O. C, on Bronto- 

saurus, 204; on Dinocerata, 221; 

on small brains of early mammals, 

223 ; causes of extinction of mam- 
mals, 245 

Marsupials in IV.lagonian miocene, 

224 ; of the Australian type still 
living in the Ancles, 241 

Martius's flora of Brazil, 57 
Mastigophora, 336 
Mastodon in S. America, 235 
Mastodon americanus, skeleton of, 231 
Mastodons, less developed elephants, 

230 
Max Verworn on chemistry of proto- 
plasm, 292 ; on vital force, 293 
Mediocrity, recession towards, 103 
Mediterranean flora, species in, 31 
Megatherium, extinct ground sloth, 

237 
Megatherium giganteiun, restoration 

of, 237 

Mendelism and mutation inefficient 
as substitutes for Darwinian evolu- 
tion, 123 

Merrill, Mr. E. D., on flora of the 
Philippines, 50 

Mesozoic era, 197 ; mammalia of, 
212; insects of, 212; life-develop- 
ment of, 215 

Metals, the seven ancient, 359 ; 
essential for civilisation, 360 

Metamorphosis of insects, 297 

Mexico and Central America, flora of, 
60 

Microbes, use of in nature, 382 

Migration, origin of bird, 148 ; facts 
and inferences, 149-52 

Mimicry, 157 

Minahassa, N. Celebes, flora of, 5 1, 79 

Mind and purpose in life-development, 
277 ; and life, different degrees of, 
284 ; produces brain, 284 



400 



MINERALS 



INDEX 



QUEENSLAND 



Minerals, number of species of, 388 
Mivart, St. George, on recognition- 
marks, 166 
Morgan, Professor L., on germinal 

selection, 271 ; on rapid cell-growth, 

348 
Mosquitoes, uses of, 135 ; description 

of Arctic, 138 ; food for most young 

birds, 146 
Mosses and hepaticae, peculiar British, 

125 
Mountain floras, in Japan, 37 ; not 

richest, 80 
Muller on insect -fertilisation of 

flowers, 308 
Mylodon, contemporary of man, 237 
Mylodon robustus, skeleton of, 237 

Narwhal's tusk an extreme develop- 
ment, 274 
Natural selection, illustrative cases 

of, 124; of sparrows at Rhode 

Island, 128; process of at Porto 

Santo, 129 
Nature, the sanctity of, 279 ; our 

defacement of, 279 ; is it cruel ? 369 
New Guinea, biologically unique, 49 ; 

flora of, 52 ; richness of its bird 

fauna, 89, 91 
Newton, Professor A., on passenger 

pigeon, 119 
North American floras in various 

latitudes, 30 
Nototherium, extinct Australian 

wombat, 243 
Nuclear division, diagram of, 343 
Nucleus, importance of, 346 
Nummulites, 336 
Nuts, why intended to be eaten, 313 

Ocean, carbon in, 364 

Orchids, abundance of in Cape 
Peninsula and New South Wales, 
38 ; in British India, 44 

Oreodontid^, early American rumi- 
nants, 227 

Organising spirit the cause of life- 
production and control, 395 

Organs, beginnings of new, 253 

Ornithosauria, 209 

Pain, its purpose and limitations, 369; 
a product of evolution, 374 ; bene- 
ficent purpose of, 375 ; where use- 
less does not exist, 376 ; in nature, 
Huxley's exaggerated view of, 371, 
384 



PaL/EOMAStodons, early elephants, 

228-9 
Palveotherium magnum, restoration of 

227 
Paleozoic era described, 191 
Palms, abundance of in the Malay 

Peninsula, 45 ; in the Philippines, 50 
Pangerango, Mount, rich flora of, 74 
Paradoxides bohemicus, 267 
Pariasatirus bainii, skeleton of, 198 
Passenger pigeon now extinct, 116; 

enormous population of less than a 

century ago, 1 16 
Penang, rich flora of, 72 
Phascolotherium, 213 
Phenacodus prit/itevus, early ungulate, 

219 
Philippines, rich flora of, 50 
Physiological allegory on growth, 

296 
Plant-cell, Kerner on, 344 ; identity 

with animal cell, 345 
Plants of wide distribution, 19; 

abundance of compared, 2 1 ; of very 

small areas, numbers of, 81 
Pleistocene mammalia, teachings of, 

242 
Plesiosaurus macroceplialus, skeleton of, 

207 
Poe, extracts from supposed impres- 

sional poem by, 398 
Porto Santo rabbits, newly formed 

species, 127 
Potentilla rupestris, one locality in 

Britain, 24 
Poulton, Prof. E. B., on beginnings 

of new organs, 253 
Primates, fossil species of South 

America, 233 
Primula imperialis, small range, 18 
Proteid molecule, complexity of, 

355 

Prothylacinus, a Patagonian mar- 
supial, 224 

Protoplasm, its chemical nature, 292 

Pteranodon occidentalis, skeleton of, 
2IO; longiceps, skull of, 21 1 

Pterodactyl, restoration of long- 
tailed, 210 

Pterodactylus spectabilis, skeleton of, 
209 

Ptychoceras emericianum, 269 

Purpose of our universe to produce 
variety of human character, 277, 393 

Pyrotheria, 235 

Queensland, flora of, 54 



RABBITS 



INDEX 



TABLE 



407 



Rabbits, increase of in Australia, 1 14 
Radiolaria, 336 
Radium, its rarity and uses, 361 
Ramsay, Sir A. , on life of the Cambrian 

age, 192 
Recognition by butterflies, 167 
Recognition-marks important for 

evolution, 156; explained, 15S ; 

objection to answered, 165 ; general 

conclusions on, 171 
Religion, gradual rise of a true, 280 
Reptiles, earliest, 19S 
Reptilian life of secondary period. 

21 1 
Retrogressive development in birds, 

286 
Rhizopoda, 336 

Rice-bird, diagram of variation of, 110 
Ridley, Mr., on flora of Singapore, 73 
River-basins, rate of denudation of, 

175 
Roscoe, Sir H., on properties of 
carbon, 363 ; on water in relation 
to life, 366 

Saleeby, Dr., on eternity as an ex- 
planation, 351 
Sap, extreme production of, 277 
Sauropterygia, 207 
Scales on wings of butterflies, 301 ; 

apparent purpose of, 303 
Scelidosaurus harrisoni, skeleton of, 

202 
Sceloditherkan Icptocephalum, skeleton 

of, 238 
Sclater, Dr. P. L., on species of 

birds, 88 
Seebohm, H., on food of birds in 

Arctic regions, 136 
Seton -Thompson on recognition- 
marks, 159 
Sharpe, Dr. B. , on species of birds, 88 
Shipley, A. E., table of described 

animals, 92 
Simethis bicolor, one locality of in 

Britain, 24 
Singapore, flora of, 72 ; destruction 

of forest in, 77 
Sisymbrium sophia, power of increase 

of, 113 
Small-brained animals, purpose of, 

284 
South Africa, Cape Region, flora 

of, 72 
South America, tertiary mammals of, 

233 
Spalacotherium, 213 



Sparrows at Rhode Island, work of 
natural selection on, 128 

Species defined, 1 1 ; distribution of, 
12 ; uncertainty of limits of, 23 ; 
rarity of precedes extinction, 24 ; 
number of, in relation to evolution, 
93; variation of, 104; extremely 
common, 105 ; to be seen every- 
where, 106 

Spencer, H., on co-ordination of 
variations, 256 ; reply to, 257-60 ; 
his "unknown reality" more con- 
cretely expressed, 399 

Spirit-life described (inspirationally) 
by Poe, 398 

Springbok, curious recognition-mark 
on, 162 

Spruce, Dr., on rich flora of Amazon, 

57 
Stei-rolophus flabellalus, skull of, 203 
Stone - curlews, recognition - marks 

of, 163 
Sydney, extreme abundance of orchids 

near, 38 

Table of De Candolle's botanical 
regions, 18 ; of chief natural orders 
in various floras, 21 : of number of 
species in large and small areas, 26 ; 
of number of species in different 
latitudes, 29 ; of floras of European 
countries according to latitude, 29 ; 
of floras of North American areas, 
30 ; of warm temperature floras, 33 ; 
of European floras of small areas, 
34; of extra -European temperate 
floras, 36 ; of large tropical floras, 
42 ; of chief orders of flora of British 
India, 44 ; of chief orders of tropical 
Sikkim, 45 ; of chief orders of Malay 
peninsula, 45 ; of chief orders of the 
Philippines, 50 ; of chief orders of 
Celebes, 52 ; of chief orders of 
Madagascar, 55 ; of chief orders in 
tropical American floras, 59 ; of 
chief orders of Mexico and Central 
America, 60 ; of chief orders of 
Nicaragua to Panama, 62 ; of chief 
orders of Lagoa Santa, 67 ; of 
number of species in tropical floras 
of small area, 71 ; of number of 
species in temperate floras of small 
area, 7 1 ; of distribution of lepidop- 
tera in Britain, 83 ; of distribution 
of coleoptera, 84 ; of described 
species of orders of insects, 85 ; of 
species of birds in Europe, 88 ; of 



408 



TEETH 



INDEX 



ZOOLOGICAL 



species of birds in zoological regions, 
89 ; of described species of living 
animals, 92 ; of percentage of mean 
error of variation, 112; of peculiar 
sub-species of British birds, 126 ; of 
rate of lowering of river-basins, 175 

Teeth, gradual loss of during develop- 
ment, 270 

Temperate floras compared, 28, 33, 
36 ; floras, small areas, 71 

TEMPERATURE-ADJUSTMENTSof earth's 

surface, 186 

Tertiary period, life of, 219 

Tetrabelodon, restoration of, 230 

Tctrabelodon angustidens, skeleton of, 
230 

Theriomorpha, beast-like reptiles of 
Karoo formation, S. Africa, 198 

Thompson, E. Seton, on recognition- 
marks, 159 

Thomson, Prof. J. A., on deter- 
minants, 272 ; on mechanics of the 
germ-plasm, 342 ; on nature's stern 
methods, 370 

Thought-transference the agent 
in life - production and guidance, 

394 
Thylacoleo carnifex, skull of, 240 
Titanotherium robiistum, skeleton of, 

222 
Toxodon platensis, skeleton of, 234 
TOXODONTIA, 235 
Trachycerasaon, 268 
Triconodon, 213 
Trilobites, early and late forms of, 

267 
Trinidad, flora of, 63 
Tropical floras of the world, 40 ; of 

large areas compared, 42 ; small 

areas, 71 
Tropical and temperate vegetation 

compared, 98 
Tropical vegetation, causes of rich- 
ness of, 99 
Tylor, A., on rate of denudation, 

175 

Uintatherium ingens, skeleton of, 220 ; 

cornutitm, skull of, 221 
Ungulata, early forms of, 219; 

extinct South American, 233 
Universe, purpose of the stellar, 278 



Upheaval produced by contraction, 
182 

Variation of mind as great as of 
body, 106 ; as shown in curve of 
stature, 108 ; of the various parts of 
a bird, 1 10 

Variation of species, 104 

Variations, co-ordination of, 256 

Variety in nature, purpose of, 27S ; 
the law of the universe, 385 ; cause 
and purpose of, 390 

Vegetable products in relation to 
man, 325 

Vegetation, differences of tropical 
and temperate, 98 ; early, 195 

Vernon, Dr. H. M., on variation, 
in; on parts of human body vary- 
ing independently, 112 

Vertebrates, special features in 
development of, 270 

Vital force, Max Verworn on, 293 ; 
Dr. A. Kerner on, 330 

Warming, Professor Eug., on flora of 
Lagoa Santa, 63-70 

Water in relation to life, 365 ; com- 
plex problems of, 365 ; as preparing 
earth for man, 367 

Weismann's theory of germinal selec- 
tion, 271 

Weymouth, abundance of ammonites 
at, 267 

Wilson, Alexander, on numbers of 
passenger pigeons, 11 6- 18 

Winter transformed into summer, 
142 

Wood, various qualities of, 326 

Woodruffe - Peacock on detailed 
floras, 14 ; on meadow and pasture 
plants, 16 

Woodward, Dr. A. S., on progres- 
sive developments of some charac- 
ters, 265 ; on small brains of early 
vertebrates, 270 

Wulfeiiia carinthiaca, small range of, 
18 

X-RAYS prove use of pain, 382 

Zoological regions, species of birds 
in, 89 



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366 The world of life 

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1911 






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