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Full text of "Natural selection and tropical nature; essays on descriptive and theoretical biology"

Cornell IHniversitis 



OF THE 



Bcw l^orft State College of Hericulture 

J^f.JA.7.¥r. \ ik/./^//0... 

' .-. ": 3514 




Cornell University 
Library 



The original of tliis book is in 
tlie Cornell University Library. 

There are no known copyright restrictions in 
the United States on the use of the text. 



http://www.archive.org/details/cu31924003039660 



NATUEAL SELECTION 

AND 

TKOPICAL NATURE 



NATUEAL sELEcrrcm 



TEOPICAL NATUEE 



ESSAYS ON 



DESCEIPTIVE AND THEORETICAL BIOLOGY 



AtFEED EUSSEL WALLACE 

AUTHOR OF 'the MALAY AEOHIPELAGO,' 'ISLAND LIFE,' 'DARWINISM,' 
ETC. 



NEW EDITION WITH CORRECTIONS AND ADDITIONS 



3Lonl>on 

MACMILLAN AND CO. 

AND NEW YORK 
1895 

All rights reserved 






Natural Selection. First Edition 1870. 
Reprinted 1875 

Tropical Nature. First Edition 1878 
First published together 1891. Reprinted 1895 



PEEFAOE 

The present volume consists mainly of a reprint of two 
volumes of essays — Contributions to the Theory of Natural 
Selection, which appeared in 1870, with a second edition in 
1871, and has now been many years out of print; and, 
Tropical Natwre anS, Other Essays, which appeared in 1878. 

In preparing a new edition of these works to appear as 
a single volume I have thought it advisable to omit two 
essays — that on "The Malayan Papilionidee " as being too 
technical for general readers, and that on " The Distribution 
of Animals as indicating Geographical Changes," which con- 
tains nothing that is not more fuUy treated in my other 
works. Another essay — " By - Paths in the Domain of 
Biology" — has also been partly omitted, one portion of it 
forming a short chapter on " The Antiquity and Origin of 
Man," while another portion has been incorporated in the 
chapter on " The Colours of Animals and Sexual Selection." 
More than compensating for these omissions are two new 
chapters — " The Antiquity of Man in North America " and 
" The Debt of Science to Darwin." 

Many corrections and some important additions have been 
made to the text, the chief of which are indicated in the 
table given below ; and to facilitate reference the two original 
works have separate headings, and form Parts I. and II. of 
the present volume. 



PREFACE 



Alterations in the Second Edition of 
Contributions, etc. 



1st Ed. 


2dBd. 




Present 
Volume. 


221 
223 
228 
229 

261 


221 

223a \ 
223b j" 
228a \ 
228b/ 

261 

372 
372b 


Additional facts as to birds acquiring the 
song of other species .... 

Mr. Spruce's remarks on young birds 
pairing with old .... 

Pouchet's observations on a change in 
the nests of swallows .... 

Passage omitted about nest of Golden 
Crested Warbler, which had been in- 
serted on Rennie's authority, but has 
not been confirmed by any later ob- 
servers. 

Daines Barriugton, on importance of pro- 
tection to the female bird . 

Note A 

Note B 


105 

107 

omitted 

138 
205 
209 



ADDITIONAL MATTER IN THE PRESENT VOLUME. 
Natueal Selection. 

PAGES 

Additional facts by Leroy, Spalding, Lowne, and Dixon on the 

Nest-Building and other Instincts of Birds . . . 108-112 

Dr. Abbott on Nesting of Baltimore Oriole . . .114 

Professor Jeitteles and Mr. Henry Reeks on Alterations in Mode 
of Nest-Building . . . . .115 

Tropical Nature. 
Note on Dr. Shufeldt's Investigations into the Aifinities of 
Swifts and Humming-Birds ..... 337 

The Antiquity of Man in Noeth America. 
(Additional Chapter) .... . 433-449 



The Debt of Science to Darwin. 
(Additional Chapter) .... 



. 450-475 



Pakkstone, Dorset, 
March 1891. 



CONTENTS 



NATURAL SELECTION 

I. On the Law which has Regulated the Introduction of 

New Species 

Geographical Distribution dependent on Geologic Changes — A Law deduced 
from well-known Geographical and Geological facts — The Form of a 
true system of Classification determined by this Law — Geographical 
Distribution of Organisms — Geological Distribution of the Forms of 
Life — High Organisation of very ancient Animals consistent with 
this Law — Objections to Forbes's Theory of Polarity — Eudimentary 
Organs — Conclusion ..... Pages 3-19 

II. On the Tendency or Varieties to Depart Indefinitely 

from the Original Type 

Introductory Note — Instability of Varieties supposed to prove the per- 
manent distinctness of Species — The Struggle for Existence — The 
Law of Population of Species — The Abtmdance or Earity of a Species 
dependent upon its more or less perfect Adaptation to the Conditions 
of Existence — Useful Variations will tend to Increase ; useless or 
hurtful Variations to Diminish — Superior Varieties wiU ultimately 
Extirpate the Original Species — The Partial Keversion of Domesti- 
cated Varieties explained — Lamarck's Hypothesis very different 
from that now advanced — Conclusion .... 20-33 

III. Mimicry, and other Protective Resemblances among 

Animals 

Test of true and false Theories — Importance of the Principle of UtUity 
Popular Theories of Colour in Animals — Importance of Conceal- 
ment as Influencing Colour — Special Modifications of Colour — Theory 



viu CONTENTS 



of Protective Colouring — Objection that Colour, as being dangerous, 
should not exist in Nature — Mimicry — Mimicry among Lepidoptera 
— Lepidoptera mimicking other Insects — Mimicry among Beetles — 
Beetles mimicking other Insects — Insects mimicking Species of other 
Orders — Cases of Mimicry among the Vertebrata — Mimicry among 
Snakes — Mimicry among Birds — Mimicry among Mammals — Objec- 
tions to Mr. Bates's Theory of Mimicry — Mimicry by Female Insects 
only — Cause of the dull Colours of Female Birds — Use of the gaudy 
Colours of many Caterpillars — Summary — General deductions as to 
Colour in Nature — Conclusion .... Pages 34-90 

IV. On Instestot in Man and Animals 

How Instinct may be best Studied — Definition of Instinct — Does Man 
possess Instincts ? — How Indians travel through unknown and track- 
less Forests ...... 91-97 

v. The Philosophy of Birds' Nests 

Instinct or Reason in the Construction of Birds' Nests — Do Men build by 
Keason or by Imitation ? — Why does each Bird build a peculiar kind 
of Nest ? — How do young Birds learn to build their first Nest ? 
Do Birds sing by Instinct or by Imitation ? — How young Birds may 
learn to build Nests — The Skill exhibited in Nest-building Ex- 
aggerated — Man's Works mainly Imitative — Birds do Alter and 
Improve their Nests when altered Conditions require it — Conclusion 

98-117 

VI. A Theory of Birds' Nests 

Changed Conditions and persistent Habits as influencing Nidification — 
Classification of Nests — Sexual differences of Colour in Birds — The 
Law which connects the Colours of Female Birds vrith the mode of 
Nidification — What the Facta Teach us — Colour more variable than 
Structure or Habits, and therefore the Character which has generally 
been Modified — Exceptional cases confirmatory of the above Explana- 
tion — Real or apparent exceptions to the Law stated at page 124 — 
Various modes of Protection of Animals — Females of some groups 
require and obtain more Protection than the Males — Conclusion 

118-140 

VII. Creation by Law 

Laws from which the Origin of Species may be deduced — Mr. Darwin's 
Metaphors liable to Misconception — A case of Orchid-structure ex- 



CONTENTS 



plained by Natural Selection — Adaptation brought about by General 
Laws — Beauty in Nature — How New Forms are produced by Varia- 
tion and Selection — The Objection that there are Limits to Variation 
— Objection to the Argument from Classification — The TiAnes on 
Natural Selection — Intermediate or generalised Forms of Extinct 
Animals an indication of Transmutation or Development — Conclu- 
sion — A Demonstration of the Origin of Species by Natural Selection 

Pages 141-166 



VIII. The Development op Human Races under the Law 
OP Natural Selection 

Vide differences of Opinion as to Man's Origin — Outline of the Theory 
of Natural Selection — Different Effects of Natural Selection on 
Animals and on Man — Influence of External Nature in the develop- 
ment of the Human Mind — Extinction of Lower Races — The Origin 
of the Races of Man — The Bearing of these Views on the Antiquity 
of Man — Their Bearing on the Dignity and Supremacy of Man — 
Their Bearing on the future Development of Man — Summary — Con- 
clusion ....... 167-185 



IX. The Limits op Natural Selection as Applied to Man 

What Natural Selection can Not do — The Brain of the Savage shown 
to be Larger than he Needs it to be — Size of Brain an important 
Element of Mental Power — Comparison of the Brains of Man and of 
Anthropoid Apes — Range of Intellectual Power in Man — Intellect of 
Savages and of Animals compared — The use of the Hairy Covering 
of Mammalia — The Constant Absence of Hair from certain parts of 
Man's body a remarkable Phenomenon — Savage Man feels the want 
of this Hairy Covering — Man's Naked Skin could not have been pro- 
duced by Natural Selection — Feet and Hands of Man considered as 
Difficulties on the Theory of Natural Selection — The Voice of Man — 
—The Origin of some of Man's Mental Faculties, by the preservation 
of Useful Variations, not possible — Difficulty as to the Origin of the 
Moral Sense — Summary of the Argument as to the Insufficiency of 
Natural Selection to account for the Development of Man — The 
Origin of Consciousness — The Nature of Matter — Matter is Force 
^1 Force is probably Will-force— Conclusion . . 186-214 



CONTENTS 



TROPICAL NATURE AND OTHER ESSAYS 

I. The Climate and Phtsioal Aspects of the Equatoeial 

Zone 

The three Climatal Zones of the Earth — Temperature of the Equatorial 
Zone — Causes of the Uniform High Temperature near the Equator — 
Influence of the Heat of the Soil — Influence of the Aqueous Vapour 
of the Atmosphere — Influence of Winds on the Temperature of the 
Equator — Heat due to the Condensation of Atmospheric Vapour — 
General Features of the Equatorial Climate — Uniformity of the 
Equatorial Climate in all Parts of the Globe — Effects of Vegetation 
on Climate — Short Twilight of the Equatorial Zone — The Aspect of 
the Equatorial Heavens — Intensity of Meteorological Phenomena at 
the Equator — Concluding Eemarks . . Pages 217-237 



II. Equatoriai, Vegetation 

The Equatorial Forest-belt and its Causes— General Features of the Equa- 
torial Forests — Characteristics of the Larger Forest- Trees — Flowering 
Trunks and their Probable Cause — Uses of Equatorial Forest-trees — 
The Climbing Plants of the Equatorial Forests — Palms— Uses of Palm- 
trees and their Products — Ferns — Ginger-worts and Wild Bananas — 
Arums— Screw-pines — Orchids— Bamboos— Uses of the Bamboo — Man- 
groves — Sensitive Plants — Comparative Scarcity of Flowers — Con- 
cluding Eemarks on Tropical Vegetation . . . 238-269 



III. Animal Life in the Tropical Forests 

Difficulties of the Subject — General Aspect of the Animal Life of Equa- 
torial Forests — Diurnal Lepidoptera or Butterflies — Peculiar Habits of 
Tropical Butterflies — Ants, Wasps, and Bees — Ants — Special Rela- 
tions between Ants and Vegetation — Wasps and Bees — Orthoptera 
and other Insects — Beetles — Wingless Insects — General Observations 

on Tropical Insects — Birds — Parrots — Pigeons — Pioarise — Cuckoos 

Trogons, Barbets, Toucans, and Hornbills— Passeres — Eeptiles and 
Amphibia: Lizards— Snakes— Frogs and Toads— Mammalia : Mon- 
keys—Bats—Summary of the Aspects of Animal Life in the Tropics 

270-311 



CONTENTS 



IV. HuMMiNO-BiRDs : As Illustrating the Luxuriance of 
Tropical Nature 

Structure — Colours and Ornaments — Descriptive Names — The Motions and 
Hahits of Humming-birds — Display of Ornaments by the Male — Food 
— ^Nests — Geographical Distribution and Variation — Humming-birds 
of Juan Fernandez as illustrating Variation and Natural Selection — 
The Relations and Affinities of Humming-birds — How to Determine 
Doubtful Affinities — Resemblances of Swifts and Humming-birds — 
Differences between Sun-birds and Humming-birds — Conclusion 

Pages 312-337 

V. The Colours or Animals and Sexual Selection 

General Phenomena of Colour in the Organic Worl^— Theory of Heat and 
Light as producing Colour — Changes of Colour in Animals produced 
by Coloured Light — Classification of Organic Colours — Protective 
Colours — Warning Colours — Sexual Colours — Normal Colours — The 
Nature of Colour — How Animal Colours are produced — Colour a 
Normal Product of Organisation — Theory of Protective Colours — 
Theory of Warning Colours— Imitative Warning Colours — The Theory 
of Mimicry — Theory of Sexual Colours — Colour as a means of 
Recognition — Colour proportionate to Integumentary Development — 
Selection by Females not a cause of Colour — Probable use of the 
Horns of Beetles— Cause of the greater Brilliancy of some Female 
Insects — Origin of the -Ornamental Plumage of Male Birds — 
Theory of the Display of Ornaments by Males — Natural Selection 
as neutralising Sexual Selection— Greater Brilliancy of some Female 
Birds — Colour - development as illustrated by Humming-birds — 
—Theory of Normal Colours — Local caus_es of Colour-development — 
The influence of Locality on Colour in Butterflies and birds — Sense- 
perception influenced by Colour of the Integuments— Summary on 
Colour-development in Animals .... 338-394 

VI. The Colours op Plants and the Origin op the 
Colour-Sense 

Source of Colouring Matter in Plants— Protective Coloration and Mimicry 
in Plants — Attractive Colours of Fruits— Protective Colours of Fruits 
Attractive Colours of Flowers— Attractive Odours in Flowers- 
Attractive Grouping of Flowers— Why Alpine Flowers are so Beauti- 
ful Why Allied Species of Flowers differ in Size and Beauty- 
Absence of Colour in Wind-fertilised Flowers— The same Theory of 
Colour applicable to Animals and Plants— Relation of the Colours 



CONTENTS 



of Flowers and their Geographical Distribution — Recent Views as 
to Direct Action of Light on the Colours of Flowers and Fruits — 
Concluding Remarks on the Importance of Colour in the Organic 
World— On the Origin of the Colour-sense : Supposed Increase of 
Colour-perception within the Historical Period — Concluding Remarks 
on the Colour-sense ..... Pages 395-415 



VII. The Antiqttity and Origin of Man 

Indications of Man's extreme Antiquity — Antiquity of Intellectual Man 
— Sculptures on Easter Island — North American Earthworks — The 
Great Pyramid — Conclusion .... 416-432 



VIII. The Antiquity of Man in Noeth America 

Ancient Shell Mounds — Man Coeval with Extinct Mammalia — Man in 
the Glacial Period — Palaeolithic Implements in North America — The 
Auriferous Gravels of California — Fossil Remains under the Ancient 
Lava Beds — Works of Art in the Auriferous Gravels — Human 
Remains in the Auriferous Gravels — Concluding Remarks on the 
Antiquity of Man ...... 433-449 



IX. The Debt of Science to Dabwin 

The Century before Darwin — The "Voyage of the Beagle — 7%e Jowrnal 
of Beseca-ches — Studies of Domestic Animals — Studies of Cultivated 
and Wild Plants — Researches on the Cowslip, Primrose, and Loose- 
strife — The Struggle for Existence — Geographical Distribution and 

Dispersal of Organisms — The Descent of Man and later Works 

Estimate of Darwin's Life-Work .... 450-475 



Index .,....., 476 



ESSAYS ON NATUEAL SELECTION 



ON THE LAW WHICH HAS EEGULATED THE INTRODUCTION 
OF NEW SPECIES^ 

Geographical Distribution dependent on Geologic Changes 
Every naturalist who has directed his attention to the subject 
of the geographical distribution of animals and plants must 
have been interested in the singular facts which it presents. 
Many of these facts are quite different from what would have 
been anticipated, and have hitherto been considered as highly 
curious, but quite inexplicable. None of the explanations 
attempted from the time of Linnaeus are now considered at 
all satisfactory ; none of them have given a cause sufficient 
to account for the facts known at the time, or comprehensive 
enough to include all the new facts which have since been, 
and are daily being, added. Of late years, however, a great 
light has been thrown upon the subject by geological investi- 
gations, which have shown that the present state of the earth 
and of the organisms now inhabiting it is but the last stage 
of a long and uninterrupted series of changes which it has 
undergone, and consequently, that to endeavour to explain 
and account for its present condition without any reference 
to those changes (as has frequently been done) must lead to 
very imperfect and erroneous conclusions. 

The facts proved by geology are briefly these : That 

^ This article, written at Sarawak in February 1855 and published in the 
Annals and Magadne of Natural History, September 1855, was intended to 
show that some form of evolution of one species from another was needed in 
order to explain the various classes of facts here indicated ; but at that time 
no means had been suggested by which the actual change of species could 
have been brought about. 



NATURAL SELECTION 



during an immense but unknown period the surface of the 
earth has undergone successive changes ; land has sunk be- 
neath the ocean, while fresh land has risen up from it ; 
mountain chains have been elevated ; islands have been 
formed into continents, and continents submerged till they 
have become islands ; and these changes have taken place, 
not once merely, but perhaps hundreds, perhaps thousands of 
times. — That all these operations have been more or less 
continuous but unequal in their progress, and dicing the 
whole series the organic life of the earth has undergone a 
corresponding alteration. This alteration also has been 
gradual, but complete ; after a certain interval not a single 
species existing which had lived at the commencement of the 
period. This complete renewal of the forms of life also 
appears to have occurred several times. — That from the last 
of the geological epochs to the present or historical epoch, 
the change of organic life has been gradual : the first appear- 
ance of animals now existing can in many cases be traced, 
their numbers gradually increasing in the more recent forma- 
tions, while other species continually die out and disappear, 
so that the present condition of the organic world is clearly 
derived by a natural process of gradual extinction and crea- 
tion of species from that of the latest geological periods. 
We may therefore safely infer a like gradation and natural 
sequence from one geological epoch to another. 

Now, taking this as a fair statement of the results of 
geological inquiry, we see that the present geographical dis- 
tribution of life upon the earth must be the result of all the 
previous changes, both of the surface of the earth itself and 
of its inhabitants. Many causes, no doubt, have operated of 
which we must ever remain in ignorance, and we may, there- 
fore, expect to find many details very difl&cult of explanation, 
and in attempting to give one, must allow ourselves to call 
into our service geological changes which it is highly probable 
may have occurred, though we have no direct evidence of 
their individual operation. 

The great increase of our knowledge within the last twenty 
years, both of the present and past history of the organic 
world, has accumulated a body of facts which should afford 
a sufficient foundation for a comprehensive law embracing and 



I THE INTRODUCTION OF NEW SPECIES 5 

explaining them all, and giving a direction to new researches. 
It is about ten years since the idea of such a law suggested 
itself to the writer of this essay, and he has since taken every 
opportunity of testing it by all the newly-ascertained facts 
with which he has become acquainted, or has been able to 
observe himself. These have all served to convince him of 
the correctness of his hypothesis. Fully to enter into such a 
subject would occupy much space, and it is only in con- 
sequence of some views having been lately promulgated, he 
believes, in a wrong direction, that he now ventures to present 
his ideas to the public, with only such obvious illustrations of 
the arguments and results as occur to him in a place far 
removed from all means of reference and exact information. 

A Law deduced from well-known Geographical and 
Geological Fads 

The foUovnng propositions in Organic Geography and Geo- 
logy give the main facts on which the hypothesis is founded. 

GBOGRAMT 

1. Large groups, such as classes and orders, are generally 
spread over the whole earth, while smaller ones, such as 
families and genera, are frequently confined to one portion, 
often to a very limited district. 

2. In widely distributed families the genera are often 
limited in range; in widely distributed genera well-marked 
groups of species are peculiar to each geographical district. 

3. When a group is confined to one district, and is rich in 
species, it is almost invariably the case that the most closely 
allied species are found in the same locality or in closely 
adjoining localities, and that therefore the natural sequence 
of the species by affinity is also geographical. 

4. In countries of a similar climate, but separated by a 
wide sea or lofty mountains, the families, genera, and species 
of the one are often represented by closely allied families, 
genera, and species peculiar to the other. 

GEOLOGY 

5. The distribution of the organic world in time is very 
similar to its present distribution in space. 



NATURAL SELECTION 



6. Most of the larger and some small groups extend 
through several geological periods. 

7. In each period, however, there are peculiar groups, 
found nowhere else, and extending through one or several 
formations. 

8. Species of one genus, or genera of one family occurring 
in the same geological time, are more closely allied than those 
separated in time. 

9. As, generally, in geography no species or genus occurs 
in two very distant localities without being also found in 
intermediate places, so in geology the life of a species or 
genus has not been interrupted. In other words, no group 
or species has come into existence twice. 

10. The following law may be deduced from these facts : 
Every species has come into existence coincident loth in space and 
time with a pre-existing closely allied species. 

This law agrees with, explains, and illustrates aU the facts 
connected with the following branches of the subject : 1st, 
The system of natural afiinities. 2d, The distribution of 
animals and plants in space. 3d, The same in time, including 
all the phenomena of representative groups, and those which 
Professor Forbes supposed to manifest polarity. 4th, The 
phenomena of rudimentary organs. We will briefly endeavour 
to show its bearing upon each of these. 

The Form of a true system of Classification determined 
by this Law 

If the law above enunciated be true, it follows that the 
natural series of affinities will also represent the order in 
which the several species came into existence, each one having 
had for its immediate antitype a closely allied species existing 
at the time of its origin. It is evidently possible that two or 
three distinct species may have had a common antitype, and 
that each of these may again have become the antitypes from 
which other closely allied species were created. The effect of 
this would be, that so long as each species has had but one 
new species formed on its model, the line of affinities will be 
simple, and may be represented by placing the several species 
in direct succession in a straight line. But if two or more 
species have been independently formed on the plan of a 



,1 THE INTRODUCTION OF NEW SPECIES 1 

common antitype, then the series of affinities will be com- 
pound, and can only be represented by a forked or many- 
branched line. Now, all attempts at a Natural classification 
and arrangement of organic beings show that both these plans 
have obtained in creation. Sometimes the series of affinities 
can be well represented for a space by a direct progression 
from species to species or from group to group, but it is 
generally found impossible so to continue. There constantly 
occur two or more modifications of an organ or modifications 
of two distinct organs, leading us on to two distinct series of 
species, which at length differ so much from each other as to 
form distinct genera or families. These are the parallel series 
or representative groups of naturalists, and they often occur 
in different countries, or are found fossil in different forma- 
tions. They are said to have an analogy to each other when 
they are so far removed from their common antitype as to 
differ in many important points of structure, while they stiU 
preserve a family resemblance. We thus see how difficult it 
is to determine in every case whether a given relation is an 
analogy or an affinity, for it is evident that as we go back 
along the parallel or divergent series, towards the common 
antitype, the analogy which existed between the two groups 
becomes an affinity. We are also made aware of the diffi- 
culty of arriving at a true classificafion, even in a small and 
perfect group • in the actual state of nature it is almost 
impossible, the species being so numerous and the modifica- 
tions of form and structure so varied, arising probably from 
the immense number of species which have served as anti- 
types for the existing species, and thus produced a compli- 
cated branching of the lines of affinity, as intricate as the 
twigs of a gnarled oak or the vascular system of the human 
body. Again, if we consider that we have only fragments of 
this vast system, the stem and main branches being repre- 
sented by extinct species of which we have no knowledge, 
while a vast mass of limbs and boughs and minute twigs and 
scattered leaves is what we have to place in order, so as to 
determine the true position which each originally occupied 
with regard to the others, the whole difficulty of the true 
Natural System of classification becomes apparent to us. 
We shall thus find ourselves obliged to reject all those 



NATURAL SELECTION 



systems of classification ■which arrange species or groups in 
circles, as well as those which fix a definite number for the 
divisions of each group. The latter class have been very 
generally rejected by naturalists, as contrary to nature, 
notwithstanding the ability with which they have been 
advocated ; but the circular system of affinities seems to have 
obtained a deeper hold, many eminent naturalists having to 
some extent adopted it. We have, however, never been able 
to find a case in which the circle has been closed by a direct 
and close affinity. In most cases a palpable analogy has been 
substituted, in others the affinity is very obscure or altogether 
doubtful. The complicated branching of the lines of affinities 
in extensive groups must also affijrd great facilities for giving 
a show of probability to any such purely artificial arrange- 
ments. Their death-blow was given by the admirable paper 
of the lamented Mr. StricMand, published in the Annals of 
Natwral History, in which he so clearly showed the true 
synthetical method of discovering the Natural System. 

Geographical Distribution of Organisms 
If we now consider the geographical distribution of animals 
and plants upon the earth, we shall find all the facts beautifully 
in accordance with, and readily explained by, the present 
hypothesis. A country having species, genera, and whole 
families peculiar to it, will be the necessary result of its 
having been isolated for a long period, sufficient for many 
series of species to have been created on the type of pre- 
existing ones, which, as well as many of the earlier-formed 
species, have become extinct, and thus made the groups 
appear isolated. If in any case the antitype had an extensive 
range, two or more groups of species might have been formed, 
each varying from it in a different manner, and thus producing 
several representative or analogous groups. The Sylviadte of 
Europe and the Sylvicolidse of North America, the Heliconidse 
of South America and the Euploeas of the East, the group of 
Trogons inhabiting Asia and that peculiar to South America, 
are examples that may be accounted for in this manner. 

Such phenomena as are exhibited by the Galapagos Islands, 
which contain little groups of plants and animals peculiar to 
themselves, but most nearly allied to those of South America, 



THE INTRODUCTION OF NEW SPECIES 



have not hitherto received any, even a conjectural explana- 
tion. The Galapagos are a volcanic group of high antiquity, 
and have probably never been more closely connected with 
the continent than they are at present. They must have 
been first peopled, like other newly-formed islands, by the 
action of winds and currents, and at a period sufficiently 
remote to have had the original species die out, and the modi- 
fied prototypes only remain. In the same way we can account 
for the separate islands having each their peculiar species, 
either on the supposition that the same original emigration 
peopled the whole of the islands with the same species from 
which differently modified prototypes were created, or that the 
islands were successively peopled from each other, but that 
new species have been created in each on the plan of the pre- 
existing ones. St. Helena is a similar case of a very ancient 
island having obtained an entirely peculiar, though limited, 
flora. On the other hand, no example is known of an island 
which can be proved geologically to be of very recent origin 
(late in the Tertiary, for instance), and yet possesses generic 
or family groups, or even many species peculiar to itself. 

When a range of mountains has attained a great eleva- 
tion, and has so remained during a long geological period, 
the species of the two sides at and near their bases will be 
often very different, representative species of some genera 
occurring, and even whole genera being peculiar to one side 
only, as is remarkably seen in the case of the Andes and 
Eocky Mountains. A similar phenomenon occurs when an 
island has been separated from a continent at a very early 
period. The shallow sea between the Peninsula of Malacca, 
Java, Sumatra, and Borneo was probably a continent or large 
island at an early epoch, and may have become submerged as 
the volcanic ranges of Java and Sumatra were elevated ; the 
organic results we see in the very considerable number of 
species of animals common to some or all of these countries, 
while at the same time a number of closely allied repre- 
sentative species exist peculiar to each, showing that a con- 
siderable period has elapsed since their separation. The facts 
of geographical distribution and of geology may thus mutu- 
ally explain each other in doubtful cases, should the prin- 
ciples here advocated be clearly established. 



10 NATURAL SELECTION i 

In all ttose cases in whicli an island has been separated 
from a continent, or raised by volcanic or coralline action 
from the sea, or in which a mountain-chain has been elevated 
in a recent geological epoch, the phenomena of peculiar 
groups or even of single representative species will not exist. 
Our own island is an example of this, its separation from the 
continent being geologically very recent, and we have con- 
sequently scarcely a species which is peculiar to it ; while the 
Alpine range, one of the most recent mountain elevations, 
separates faunas and floras which scarcely differ more than 
may be due to climate and latitude alone. 

The series of facts alluded to in Proposition (3), of closely 
allied species in rich groups being found geographically near 
each other, is most striking and important. Mr. Lovell 
Eeeve has well exemplified it in his able and interesting 
paper on the Distribution of the Bulimi. It is also seen in 
the Humming-birds and Toucans, little groups of two or three 
closely allied species being often found in the same or closely 
adjoining districts, as we have had the good fortune of per- 
sonally verifying. Fishes give evidence of a similar Mnd : 
each great river has its peculiar genera, and in more extensive 
genera its groups of closely allied species. But it is the same 
throughout Nature ; every class and order of animals will 
contribute similar facts. Hitherto no attempt has been 
made to explain these singular phenomena, or to show how 
they have arisen. Why are the genera of Palms and of 
Orchids in almost every case confined to one hemisphere? 
Why are the closely allied species of brown-backed Trogons 
all found in the East, and the green-backed in the West? 
Why are the Macaws and the Cockatoos similarly restricted ? 
Insects furnish a countless number of analogous examples — 
the Goliathi of Africa, the Ornithopterse of the Indian 
Islands, the Heliconidss of South America, the Danaidse of 
the East, and in all the most closely allied species found in 
geographical proximity. The question forces itself upon 
every thinking mind. Why are these things so ? They 
could not be as they are had no law regulated their creation 
and dispersion. The law here enunciated not merely ex- 
plains but necessitates the facts we see to exist, while the 
vast and long - continued geological changes of the earth 



I THE INTRODUCTION OF NEW SPECIES 11 

readily account for the exceptions and apparent discrepancies 
that here and there occur. The writer's object in putting 
forward his views in the present imperfect manner is to 
submit them to the test of other minds, and to be made 
aware of all the facts supposed to be inconsistent with them. 
As his hypothesis is one which claims acceptance solely as 
explaining and connecting facts which exist in nature, he 
expects facts alone to be brought to disprove it, not h priori 
arguments against its probability. 

Geological Distribution of the Forms of Life 

The phenomena of geological distribution are exactly 
analogous to those of geography. Closely aUied species are 
found associated in the same beds, and the change from 
species to species appears to have been as gradual in time as 
in space. Geology, however, furnishes us with positive proof 
of the extinction and production of species, though it does 
not inform us how either has taken place. The extinction of 
species, however, oifers but little difficulty, and the modus 
operandi has been well illustrated by Sir C. Lyell in his ad- 
mirable Principles. Geological changes, however gradual, 
must occasionally have modified external conditions to such 
an extent as to have rendered the existence of certain species 
impossible. The extinction would in most cases be effected 
by a gradual dying-out, but in some instances there might 
have been a sudden destruction of a species of limited range. 
To discover how the extinct species have from time to time 
been replaced by new ones down to the very latest geological 
period, is the most diflScult, and at the same time the most 
interesting problem in the natural history of the earth. The 
present inquiry, which seeks to eliminate from known facts 
a law which has determined, to a certain degree, what species 
could and did appear at a given epoch, may, it is hoped, be 
considered as one step in the right direction towards a com- 
plete solution of it. 

High Organisation of very ancient Animals consistent 
with this Law 
Much discussion has of late years taken place on the 
question whether the succession of life upon the globe has 



12 ' NATURAL SELECTION i 

been from a lower to a higter degree of organisation. The 
admitted facts seem to show that there has been a general, 
but not a detailed progression. MoUusca and Eadiata existed 
before Vertebrata, and the progression from Fishes to Eeptiles 
and Mammalia, and also from the lower mammals to the 
higher, is indisputable. On the other hand, it is said that 
the Mollusca and Eadiata of the very earliest periods were 
more highly organised than the great mass of those now 
existing, and that the very first fishes that have been dis- 
covered are by no means the lowest organised of the class. 
Now it is believed the present hypothesis wiU harmonise with 
all these facts, and in a great measure serve to explain them ; 
for though it may appear to some readers essentially a theory 
of progression, it is in reality only one of gradual change. 
It is, however, by no means difficult to show that a real pro- 
gression in the scale of organisation is perfectly consistent 
with all the appearances, and even with apparent retrogression, 
should such occur. 

Eeturning to the analogy of a branching tree, as the best mode 
of representing the natural arrangement of species and their 
successive creation, let us suppose that at an early geological 
epoch any group (say a class of the Mollusca) has attained to 
a great richness of species and a high organisation. Now let 
this great branch of allied species, by geological mutations, 
be completely or partially destroyed. Subsequently a new 
branch springs from the same trunk — ^that is to say, new 
species are successively created, having for their antitypes the 
same lower organised species which had served as the anti- 
types for the former group, but which have survived the 
modified conditions which destroyed it. This new group 
being subject to these altered conditions, has modifications of 
structure and organisation given to it, and becomes the repre- 
sentative group of the former one in another geological form- 
ation. It may, however, happen, that though later in time, 
the new series of species may never attain to so high a degree 
of organisation as those preceding it, but in its turn become 
extinct, and give place to yet another modification from the 
same root, which may be of higher or lower organisation, 
more or less numerous in species, and more or less varied in 
form and structure, than either of those which preceded it 



1 THE INTRODUCTION OF NEW SPECIES 13 

Again, each of these groups may not have become totally 
extinct, but may have left a few species, the modified proto- 
types of which have existed in each succeeding period, a faint 
memorial of their former grandeur and luxuriance. Thus 
every case of apparent retrogression may be in reality a pro- 
gress, though an interrupted one : when some monarch of the 
forest loses^a limb, it may be replaced by a feeble and sickly 
substitute. The foregoing remarks appear to apply to the 
case of the MoUusca, which, at a very early period, had 
reached a high organisation and a great development of forms 
and species in the testaceous Cephalopoda. In each succeed- 
ing age modified species and genera replaced the former ones 
which had become extinct, and as we approach the present 
era, but few and small representatives of the group remain, 
while the Gasteropods and Bivalves have acquired an immense 
preponderance. In the long series of changes the earth has 
undergone, the process of peopling it with organic beings has 
been continually going on, and whenever any of the higher 
groups have become nearly or quite extinct, the lower forms 
which have better resisted the modified physical conditions 
have served as the antitypes on which to found the new 
races. In this manner alone, it is believed, can the represent- 
ative groups at successive periods, and the risings and fallings 
in the scale of organisation, be in every case explained. 

Objections to Forbes' Theory of Polwrity 
The hypothesis of polarity, recently put forward by Pro- 
fessor Edward Forbes to account for the abundance ,of generic 
forms at a very early period and at present, while in the in- 
termediate epochs there is a gradual diminution and impover- 
ishment, till the minimum occin-red at the confines of the 
Palaeozoic and Secondary epochs, appears to us quite unneces- 
sary, as the facts may be readily accounted for on the principles 
already laid down. Between the Palaeozoic and Neozoic 
periods of Professor Forbes there is scarcely a species in com- 
mon, and the greater parts of the genera and families also 
disappear, to be replaced by new ones. It is almost univer- 
sally admitted that such a change in the organic world must 
have occupied a vast period of time. Of this interval we 
have no record ; probably because the whole area of the early 



14 NATURAL SELECTION I 

formations no-w exposed to our researches was elevated at the 
end of the Palseozoic period, and remained so through the 
interval required for the organic changes which resulted in 
the fauna and flora of the Secondary period. The records of 
this interval are buried beneath the ocean which covers three- 
fourths of the globe. Now it appears highly probable that a 
long period of quiescence or stability in the physical condi- 
tions of a district would be most favourable to the existence 
of organic life in the greatest abundance, both as regards 
individuals and also as to variety of species and generic group, 
just as we now find that the places best adapted to the rapid 
growth and increase of individuals also contain the greatest 
profusion of species and the greatest variety of forms, — ^the 
tropics in comparison with the temperate and arctic regions. 
On the other hand, it seems no less probable that a change in 
the physical conditions of a district, even small in amount if 
rapid, or even gradual if to a great amount, would be highly 
unfavourable to the existence of individuals, might cause the 
extinction of many species, and would probably be equally 
unfavourable to the creation of new ones. In this too we 
may find an analogy with the present state of our earth, for 
it has been shown to be the violent extremes and rapid 
changes of physical conditions, rather than the actual mean 
state in the temperate and frigid zones, which renders them 
less prolific than the tropical regions, as exemplified by the 
great distance beyond the tropics to which tropical forms 
penetrate when the climate is equable, and also by the rich- 
ness in species and forms of tropical mountain regions which 
principally differ from the temperate zone in the uniformity 
of their climate. However this may be, it seems a fair 
assumption that during a period of geological repose the new 
species which we know to have been created would have 
appeared, that the creations would then exceed in number the 
extinctions, and therefore the number of species would increase. 
In a period of geological activity, on the other hand, it seems 
probable that the extinctions might exceed the creations, and 
the number of species consequently diminish. That such 
effects did take place in connection with the causes to which 
we have imputed them, is shown in the case of the Coal 
formation, the faults and contortions of which show a period 



1 THE INTRODUCTION OF NEW SPECIES 15 

of great activity and violent convulsions, and it is in the 
formation immediately succeeding this that the poverty of 
forms of life is most apparent. We have then only to sup; 
pose a long period of somewhat similar action during the vast 
unknown interval at the termination of the Palaeozoic period, 
and then a decreasing violence or rapidity through the 
Secondary period, to allow for the gradual repopulation of 
the earth with varied forms, and the whole of the facts are 
explained.^ We thus have a clue to the increase of the forms 
of life during certain periods, and their decrease during others, 
without recourse to any causes hut those we know to have 
existed, and to effects fairly deducible from them. The pre- 
cise manner in which the geological changes of the early 
formations were effected is so extremely ohscure, that when 
we can explain important facts by a retardation at one time 
and an acceleration at another of a process which we know 
from its nature and from observation to have been unequal, — 
a cause so simple may surely be preferred to one so obscure 
and hypothetical as polarity. 

I would also venture to suggest some reasons against the 
very nature of the theory of Professor Forbes. Our know- 
ledge of the organic world during any geological epoch is 
necessarily very imperfect. Looking at the vast numbers of 
species and groups that have been discovered by geologists, 
this may be doubted ; but we should compare their numbers 
not merely with those that now exist upon the earth, but with 
a far larger amount. We have no reason for believing that 
the number of species on the earth at any former period was 
much less than at present ; at all events the aquatic portion, 
with which geologists have most acquaintance, was probably 
often as great or greater. Now we know that there have 
been many complete changes of species ; new sets of organisms 
have many times been introduced in place of old ones which 
have become extinct, so that the total amount which have 
existed on the earth from the earliest geological period must 
have borne about the same proportion to those now living, as 
the whole human race who have lived and died upon the 

^ Professor Eamsay has since sliown that a glacial epoch prohahly occurred 
at the time of the Permian formation, which will more satisfactorily account 
for the comparative poverty of species. 



16 NATURAL SELECTION I 

eartli to the population at the present time. Again, at each 
epoch, the whole earth was, no doubt, as now, more or less the 
theatre of life, and as the successive generations of each species 
died, their exuviae and preservahle parts would be deposited 
over every portion of the then existing seas and oceans, which 
we have reason for supposing to have been more, rather than 
less, extensive than at present. In order then to understand 
our possible knowledge of the early world and its inhabitants, 
we must compare, not the area of the whole field of our geo- 
logical researches with the earth's surface, but the area of the 
examined portion of each formation separately with the whole 
earth. For example, during the Silurian period all the earth 
was Silurian, and animals were living and dying and deposit 
ing their remains more or less over the whole area of the 
globe, and they were probably (the species at least) nearly as 
varied in different latitudes iind longitudes as at present. 
What proportion do the Silurian districts bear to the whole 
surface of the globe, land and sea (for far more extensive 
Silurian districts probably exist beneath the ocean than above 
it), and what portion of the known Silurian districts has been 
actually examined for fossils? Would the area of rock 
actually laid open to the eye be the thousandth or the ten- 
thousandth part of the earth's surface? Ask the same 
question with regard to the Oolite or the Chalk, or even to 
particular beds of these when they differ considerably in their 
fossils, and you may then get some notion of how small a 
portion of the whole we know. 

But yet more important is the probability, nay, almost the 
certainty, that whole formations containing the records of 
vast geological periods are entirely buried beneath the ocean, 
and for ever beyond our reach. Most of the gaps in the 
geological series may thus be filled up, and vast numbers of 
unknown and unimaginable animals, which might help to 
elucidate the affinities of the numerous isolated groups which 
are a perpetual puzzle to the zoologist, may there be buried, 
till future revolutions may raise them in their turn above the 
waters, to afford materials for the study of whatever race of 
intelligent beings may then have succeeded us. These con- 
siderations must lead us to the conclusion that our knowledge 
of the whole series of the former inhabitants of the earth is 



I THE INTRODUCTION OF NEW SPECIES 17 

necessarily most imperfect and fragmentary, — as much so as 
our knowledge of the present organic world would be, were 
we forced to make our collections and observations only in 
spots equally limited in area and in number with those 
actually laid open for the collection of fossils. Now, the 
hypothesis of Professor Forbes is essentially one that assumes 
to a great extent the completeness of our knowledge of the 
whole series of organic beings which have existed on the 
earth. This appears to be a fatal objection to it, inde- 
pendently of all other considerations. It may be said that 
the same objections exist against every theory on such a sub- 
ject, but this is not necessarily the case. The hypothesis put 
forward in this paper depends in no degree upon the com- 
pleteness of our knowledge of the former condition of the 
organic world, but takes what facts we have as fragments of 
a vast whole, and deduces from them something of the nature 
and proportions of that whole which we can never know in 
detail. It is founded upon isolated groups of facts, recognises 
their isolation, and endeavours to deduce from them the 
nature of the intervening portions. 

Budimeniary Organs 

Another important series of facts, quite in accordance 
with, and even necessary deductions from, the law now 
developed, are those of rudimentary organs. That these 
really do exist, and in most cases have no special function in 
the animal economy, is admitted by the first authorities in 
comparative anatomy. The minute limbs hidden beneath the 
skin in many of the snake-like lizards, the anal hooks of the 
boa constrictor, the complete series of jointed finger-bones in 
the paddle of the Manatus and whale, are a few of the most 
familiar instances. In botany a similar class of facts has been long 
recognised. Abortive stamens, rudimentary floral envelopes 
and undeveloped carpels, are of the most frequent occurrence. 
To every thoughtful naturalist the question must arise. What 
are these for 1 What have they to do with the great laws of 
creation? Do they not teach us something of the system 
of Nature ? If each species has been created independently, 
and without any necessary relations with pre-existing species, 
what do these rudiments, these apparent imperfections mean 1 

G 



18 NATURAL SELECTION i 

There must be a cause for them ; they must be the necessary 
results of some great natural law. Now, if, as it has been 
endeavoured to be shown, the great law which has regulated 
the peopling of the earth with animal and vegetable life is, 
that every change shall be gradual; that no new creature 
shall be formed widely differing from anything before exist- 
ing ; that in this, as in everything else in nature, there shall 
be gradation and harmony, — ^then these rudimentary organs 
are necessary, and are an essential part of the system of 
nature. Ere the higher Vertebrata were formed, for instance, 
many steps were required, and many organs had to undergo 
modifications from the rudimental condition in which only 
they had as yet existed. We still see remaining an antitypal 
sketch of a wing adapted for flight in the scaly flapper of the 
penguin, and limbs first concealed beneath the skin, and then 
weakly protruding from it, were the necessary gradations 
before others should be formed fully adapted for locomotion.^ 
Many more of these modifications should we behold, and more 
complete series of them, had we a view of all the forms which 
have ceased to live. The great gaps that exist between fishes, 
reptiles, birds, and mammals would then, no doubt, be 
softened down by intermediate groups, and the whole organic 
world would be seen to be an unbroken and harmonious 
system. 

Conclusion 

It has now been shown, though most briefly and imper- 
fectly, how the law that " Every species has come info existence 
coincident both in time and space with a pre-existing closely allied 
species," connects together and renders intelligible a vast 
number of independent and hitherto unexplained facts. The 
natural system of arrangement of organic beings, their geo- 
graphical distribution, their geological sequence, the pheno- 
mena of representative and substituted groups in all their 
modifications, and the most singular peculiarities of anatomical 
structure, are all explained and illustrated by it, in perfect 
accordance with the vast mass of facts which the researches of 
modern naturalists have brought together, and, it is believed 

' The theory of Natural Selection has now taught us that these are not the 
steps by which limbs have been formed ; and that most rudimentary organs 
have been produced by abortion, owing to disuse, as explained by Mr. Darwin. 



I THE INTRODUOTION OF NEW SPECIES 19 

not materially opposed to any of them. It also claims a 
superiority over previous hypotteses, on the ground that it 
not merely explains, but necessitates what exists. Granted 
the law, and many of the most important facts in Nature 
could not have been otherwise, but are almost as necessary 
deductions from it as are the elliptic orbits of the planets 
from the law of gravitation. 



INTKODUCTOEY NOTE TO CHAPTER II IN PRESENT EDITION 

As this chapter sets forth the main features of a theory 
identical with that discovered by Mr. Darwin many years 
before but not then published, and as it has thus an historical 
interest, a few words of personal statement may be permissible. 
After writing the preceding paper the question of how changes 
of species could have been brought about was rarely out of 
my mind, but no satisfactory conclusion was reached till 
February 1858. At that time I was suifering from a rather 
severe attack of intermittent fever at Ternate in the Moluccas, 
and one day while lying on my bed during the cold fit, 
wrapped in blankets, though the thermometer was at 88° 
F., the problem again presented itself to me, and something 
led me to think of the "positive checks" described by Malthus 
in his "Essay on Population," a work I had read several 
years before, and which had made a deep and permanent 
impression on my mind. These checks — war, disease, famine 
and the like — must, it occurred to me, act on animals as well 
as on man. Then I thought of the enormously rapid multi- 
plication of animals, causing these checks to be much more 
effective in them than in the case of man ; and while ponder- 
ing vaguely on this fact there suddenly flashed upon me the 
idea of the survival of the fittest — that the individuals removed 
by these checks must be on the whole inferior to those that 
survived. In the two hours that elapsed before my ague fit 
was over I had thought out almost the whole of the theory, 
and the same evening I sketched the draft of my paper, and 
in the two succeeding evenings wrote it out in full, and sent 
it by the next post to Mr. Darwin. Up to this time the only 
letters I had received from him were those printed in the 
second volume of his Life and Letters, (vol. ii. pp. 95 and 108), 



mTRODUCTORY NOTE TO CHAPTER II 21 

in which he speaks of its being the twentieth year since he 
" opened his first note-book on the question how and in what 
way do species and varieties differ from each other," and after 
referring to oceanic islands, the means of distribution of land- 
shells, etc., added : " My work, on which I have now been at 
work more or less for twenty years, mil not Jix or settle any- 
thing; but I hope it will aid by giving a large collection of 
facts, with one definite end." The words I have italicised, 
and the whole tone of his letters, led me to conclude that he 
had arrived at no definite view as to the origin of species, and 
I fully anticipated that my theory would be new to him, 
because it seemed to me to settle a great deal. The imme- 
diate result of my paper Tvas that Darwin was induced at 
once to prepare for publication his book on the Origin of 
Species in the condensed form in which it appeared, instead of 
waiting an indefinite number of years to complete a work On 
a much larger scale which he had partly written, but which 
in all probability would not have carried conviction to so 
many persons in so short a time. I feel much satisfaction in 
having thus aided in bringing about the publication of this 
celebrated book, and with the ample recognition by Darwin 
himself of my independent discovery of " natural selection." 
(See Origin of Species, 6th ed., introduction, p. 1, and lAfe and 
Letters, vol. ii. chap, iv., pp. 115-129 and 145.) 



II 



ON THE TENDENCY OF VARIETIES TO DEPART INDEFINITELY 
FROM THE ORIGINAL TYPE 

Instability of Varieties supposed to prove the permanent 
distinctness of Species 

One of the strongest arguments whicli have been adduced 
to prove the original and permanent distinctness of species is, 
that mrieties produced in a state of domesticity are more or 
less imstable, and often have a tendency, if left to them- 
selves, to return to the normal form of the parent species ; 
and this instability is considered to be a distinctive peculi- 
arity of all varieties, even of those occurring among wild 
animals in a state of nature, and to constitute a provision 
for preserving unchanged the originally created distinct 
species. 

In the absence or scarcity of facts and observations as to 
varieties occurring among wild animals, this argument has had 
great weight with naturalists, and has led to a very general 
and somewhat prejudiced belief in the stability of species. 
Equally general, however, is the belief in what are called 
" permanent or true varieties," — races of animals which con- 
tinually propagate their like, but which differ so slightly 
(although constantly) from some other race, that the one is 
considered to be a variety of the other. Which is the variety 
and which the original species, there is generally no means 
of determining, except in those rare cases in which the 
one race has been known to produce an offspring unlike itself 
and resembling the other. This, however, would seem quite 
incompatible with the "permanent invariability of species," 



II ON THE TENDENCY OF VARIETIES, ETC. 23 

but the difficulty is overcome by assuming that such varieties 
have strict limits, and can never again vary further from the 
original type, although they may return to it, which, from the 
analogy of the domesticated animals, is considered to be highly 
probable, if not certainly proved. 

It will be observed that this argument rests entirely on the 
assumption that varieties occurring in a state of nature are 
in all respects analogous to or even identical with those of 
domestic animals, and are governed by the same laws as 
regards their permanence or further variation. But it is the 
object of the present paper to show that this assumption is 
altogether false, that there is a general principle in nature 
which wiU cause many varieties to survive the parent species, 
and to give rise to successive variations departing further and 
further from the original type, and which also produces, in 
domesticated animals, the tendency of varieties to return to 
the parent form. 

The Struggle for Existence 

The life of wild animals is a struggle for existence. The 
full exertion of all their faculties and all their energies is 
required to preserve their own existence and provide for that 
of their infant offspring. The possibility of procuring food 
during the least favourable seasons, and of escaping the 
attacks of their most dangerous enemies, are the primary 
conditions which determine the existence both of individuals 
and of entire species. These conditions will also determine 
the population of a species ; and by a careful consideration of 
all the circumstances we may be enabled to comprehend, and 
in some degree to explain, what at first sight appears so 
inexplicable — the excessive abundance of some species, whUe 
others closely allied to them are very rare. 

The Law of Population of Species 
The general proportion that must obtain between certain 
groups of ' animals is readily seen. Large animals cannot be 
so abundant as small ones; the carnivora must be less 
numerous than the herbivora ; eagles and lions can never be 
so plentiful as pigeons and antelopes ; and the wild asses of 
the Tartarian deserts cannot equal in numbers the horses of 



24 NATURAL SELECTION n 

i— 

tte more luxuriant prairies and pampas of America. The 
greater or less fecundity of an animal is often considered to 
be one of the chief causes of its abundance or scarcity ; but a 
consideration of the facts will show us that it really has little 
or nothing to do with the matter. Even the least prolific of 
animals would increase rapidly if unchecked, whereas it is 
evident that the animal population of the globe must be 
stationary, or perhaps, through the influence of man, decreasing. 
Fluctuations there may be ; but permanent increase, except in 
restricted localities, is almost impossible. For example, our 
own observation must convince us that birds do not go on 
increasing every year in a geometrical ratio, as they would 
do were there not some powerful check to their natural 
increase. Very few birds produce less than two young ones 
each year, while many have six, eight, or ten ; four will 
certainly be below the average ; and if we suppose that each 
pair produce young only four times in their life, that will 
also be below the average, supposing them not to die either 
by violence or want of food. Yet at this rate how tremendous 
would be the increase in a few years from a single pair ! A 
simple calculation will show that in fifteen years each pair of 
birds would have increased to nearly ten millions ! i whereas 
we have no reason to believe that the number of the birds of 
any country increases at all in fifteen or in one hundred and 
fifty years. With such powers of increase the population 
must have reached its limits, and have become stationary, in 
a very few years after the origin of each species. It is 
evident, therefore, that each year an immense number of 
birds must perish — as many in fact as are born ; and as on 
the lowest calculation the progeny are each year twice as 
numerous as their parents, it follows that, whatever be the 
average number of individuals existing in any given country, 
twke that nurnier .must perish annually, — a striking result, but 
one which seems at least highly probable, and is perhaps 
under rather than over the truth. It would therefore appear 
that, so far as the continuance of the species and the keeping 
up the average number of individuals are concerned, large 
broods are superfluous. On the average all above one become 

^ This is under estimated. The number would really amount to more 
than two thousand millions ! 



II ON THE TENDENCY OF VARIETIES, ETC. 25 

food for hawks and Mtes, wild cats or weasels, or perish of 
cold and hunger as winter comes on. This is strikingly 
proved by the case of particular species ; for we find that 
their abundance in individuals bears no relation whatever to 
their fertility in producing offspring. 

Perhaps the most remarkable instance of an immense bird 
population is that of the passenger pigeon of the United 
States, which lays only one, or at most two eggs, and is said 
to rear generally but one young one. Why is this bird so 
extraordinarily abundant, while others producing two or three 
times as many young are much less plentiful ? The explana- 
tion is not difficult. The food most congenial to this species, 
and on which it thrives best, is abundantly distributed over 
a very extensive region, offering such difierences of soil and 
climate, that in one part or another of the area the supply 
never fails. The bird is capable of a very rapid and long- 
continued flight, so that it can pass without fatigue over the 
whole of the district it inhabits, and as soon as the supply of 
food begins to fail in one place is able to discover a fresh 
feeding-ground. This example strikingly shows us that the 
procuring a constant supply of wholesome food is almost the 
sole condition requisite for ensuring the rapid increase of a 
given species, since neither the limited fecundity nor the un- 
restrained attacks of birds of prey and of man are here 
sufficient to check it. In no other birds are these peculiar 
circumstances so strikingly combined. Either their food is 
more liable to failure, or they have not sufficient power of 
wing to search for it over an extensive area, or during some 
season of the year it becomes very scarce, and less wholesome 
substitutes have to be found ; and thus, though more fertile 
in offspring, they can never increase beyond the supply of 
food in the least favourable seasons. 

Many birds can only exist by migrating, when their food 
becomes scarce, to regions possessing a milder, or at least a 
different climate, though, as these migrating birds are seldom 
excessively abundant, it is evident that the countries they 
visit are still deficient in a constant and abundant supply of 
wholesome food. Those whose organisation does not permit 
them to migrate when their food becomes periodically scarce, 
can never attain a large population. This is probably the 



26 NATURAL SELECTION n 

reason why ■woodpeckers are scarce with us, while in the 
tropics they are among the most abundant of solitary birds. 
Thus the house sparrow is more abundant than the redbreast, 
because its food is more constant and plentiful, — seeds of 
grasses being preserved during the winter, and our farm-yards 
and stubble-fields furnishing an almost inexhaustible supply. 
Why, as a general rule, are aquatic, and especially sea-birds, 
very numerous in individuals J Not because they are more 
prolific than others, generally the contrary ; but because their 
food never fails, the sea-shores and river-banks daily swarm- 
ing with a fresh supply of small moUusca and Crustacea. 
Exactly the same laws will apply to mammals. Wild cats 
are prolific and have few enemies ; why then are they never 
as abundant as rabbits ? The only intelligible answer is, that 
their supply of food is more precarious. It appears evident, 
therefore, that so long as a country remains physically un- 
changed, the numbers of its animal population cannot 
materially increase. If one species does so, some others 
requiring the same kind of food must diminish in proportion. 
The numbers that die annually must be immense ; and as the 
individual existence of each animal depends upon itself, those 
that die must be the weakest — the very young, the aged, and 
the diseased — while those that prolong their existence can 
only be the most perfect in health and vigour — those who are 
best able to obtain food regularly, and avoid their numerous 
enemies. It is, as we commenced by remarking, " a struggle 
for existence," in which the weakest and least perfectly 
organised must always succumb. 

The Abundance or Rarity of a Species dependent upon its more or 
less perfect Adaptation to the Conditions of Existence 

It seems evident that what takes place among the indi- 
viduals of a species must also occur among the several allied 
species of a group, — viz., that those which are best adapted 
to obtain a regular supply of food, and to defend themselves 
against the attacks of their enemies and the vicissitudes of the 
seasons, must necessarily obtain and preserve a superiority in 
population ; while those species which, from some defect of 
power or organisation, are the least capable of counteracting 
the vicissitudes of food-supply, etc., must diminish in numbers, 



ON THE TENDENCY OF VARIETIES, ETC. 27 



and, in extreme cases, become altogether extinct. Between 
these extremes the species will present various degrees of 
capacity for ensuring the means of preserving life ; and it is 
thus we account for the abundance or rarity of species. Our 
ignorance will generally prevent us from accurately tracing 
the effects to their causes; but could we become perfectly 
acquainted with the organisation and habits of the various 
species of animals, and could we measure the capacity of each 
for performing the different acts necessary to its safety and 
existence under all the varying circumstances by which it is 
surrounded, we might be able even to calculate the pro- 
portionate abundance of individuals which is the necessary 
result. 

If now we have succeeded in establishing these two points 
— 1st, that the animal population of a country is generally 
stationary, being kept down by a periodical deficiency of food, and 
other checks J- and, 2d, that the comparative abundance or scarcity 
of the individuals of the several species is entirely due to their 
organisation and resulting habits, which, rendering it more difficidt 
to procure a regular supply of food and to provide for their personal 
safety ^ in some cases than in others, can only be balanced by a 
difference in the population which have to exist in a given area — 
we shaU be in a condition to proceed to the consideration of 
varieties, to which the preceding remarks have a direct and 
very important application. 

Useful Variations will tend to Increase ; useless or hurtful 
Variations to Diminish 

Most or perhaps all the variations from the typical form 
of a species must have some definite effect, however slight, on 
the habits or capacities of the individuals. Even a change of 
colour might, by rendering them more or less distinguishable, 
affect their safety; a greater or less development of hair 
might modify their habits. More important changes, such as 
an increase in the power or dimensions of the Hmbs or any of 
the external organs, would more or less affect their mode of 
procuring food or the range of country which they could in- 

^ " And that of their offspring " should have been added. But it must 
be remembered that the writer had no opportunity of correcting the proofs of 
this paper. 



28 NATURAL SELECTION n 

^abit. It is also evident that most changes would affect, 
either favoiirably or adversely, the powers of prolonging 
existence. An antelope vsdth shorter or weaker legs must 
necessarily suffer more from the attacks of the feline carrd- 
vora ; the passenger pigeon vrith less powerful wings would 
sooner or later be affected in its powers of procuring a regular 
supply of food j and in both cases the result must necessarily 
be a diminution of the population of the modified species. If, 
on the other hand, any species should produce a variety 
having slightly increased powers of preserving existence, that 
variety must inevitably in time acquire a superiority in 
numbers. These results must follow as surely as old age, in- 
temperance, or scarcity of food produce an increased mortality. 
In both cases there may be many individual exceptions : but 
on the average the rule wiU invariably be found to hold good. 
All varieties will therefore fall into two classes — those which 
under the same conditions would never reach the population 
of the parent species, and those which would in time obtain 
and keep a numerical superiority. Now, let some alteration 
of physical conditions occur in the district— a long period of 
drought, a destruction of vegetation by locusts, the irruption 
of some fresh carnivorous animal seeking " pastures new " — 
any change in fact tending to render existence more diflScult 
to the species in question, and tasking its utmost powers to 
avoid complete extermination, — it is evident that, of all the 
individuals composing the species, those forming the least 
numerous and most feebly organised variety would suffer 
first, and, were the pressure severe, must soon become extinct. 
The same causes continuing in action, the parent species would 
next suffer, would gradually diminish in numbers, and with 
a recurrence of similar unfavourable conditions might also 
become extinct. The superior variety would then alone 
remain, and on a return to favourable circumstances would 
rapidly increase in numbers and occupy the place of the 
extinct species and variety. 

Superior Varieties will vltimately Extirpate the original Species 

The variety would now have replaced the species, of which 
it would be a more perfectly developed and more highly 
organised form. It would be in all respects better adaj^tcd 



II ON THE TENDENCY OF VARIETIES, ETC. 29 

to secure its safety, and to prolong its individual existence 
and that of the race. Such a variety could not return to the 
original form; for that form is an inferior one, and could 
never compete Mrith it for existence. Granted, therefore, a 
" tendency " to reproduce the original type of the species, still 
the variety must ever remain preponderant in numbers, and 
under adverse physical conditions again alone swrvive. But 
this new, improved, and populous race might itself, in course 
of time, give rise to new varieties, exhibiting several diverging 
modifications of form, any of which, tending to increase the 
facilities for preserving existence, must, by the same general 
law, in their turn become predominant. Here, then, we have 
progression and continued divergence deduced from the general 
laws which regulate the existence of animals in a state of 
nature, and from the undisputed fact that varieties do fre- 
quently occur. It is not, however, contended that this result 
would be invariable ; a change of physical conditions in the 
district might at times materially modify it, rendering the 
race which had been the most capable of supporting existence 
under the former conditions now the least so, and even 
causing the extinction of the newer and, for a time, superior 
race, while the old or parent species and its first inferior 
varieties continued to flourish. Variations in unimportant 
parts might also occur, having no perceptible efiect on the 
life-preserving powers ; and the varieties so furnished might 
run a course parallel with the parent species, either giving 
rise to further variations or returning to the former type. 
All we argue for is, that certain varieties have a tendency to 
maintain their existence longer than the original species, and 
this tendency must make itself felt ; for though the doctrine 
of chances or averages can never be trusted on a limited scale, 
yet, if applied to high numbers, the results come nearer to 
what theory demands, and, as we approach to an infinity 
of examples, become strictly accurate. Now the scale on 
which nature works is so vast — the numbers of individuals 
and the periods of time with which she deals approach 
so near to infinity — that any cause, however slight, and 
however liable to be veiled and counteracted by accidental 
circumstances, must in the end produce its full legitimate 
results. 



30 NATURAL SELECTION 



The Partial JReversion of Domesticated Varieties explained 

Let us now turn to domesticated animals, and inquire how 
varieties produced among them are affected by the principles 
here enunciated. The essential difference in the condition of 
wild and domestic animals is this, — that among the former, 
their well - being and very existence depend upon the f uU 
exercise and healthy condition of all their senses and physical 
powers, whereas, among the latter, these are only partially 
exercised, and in some cases are absolutely unused. A wild 
animal has to search, and often to labour, for every mouthful 
of food — to exercise sight, hearing, and smell in seeking it, 
and in avoiding dangers, in procuring shelter from the inclem- 
ency of the seasons, and in providing for the subsistence 
and safety of its offspring. There is no muscle of its body 
that is not called into daily and hourly activity j there is no 
sense or faculty that is not strengthened by continual exercise. 
The domestic animal, on the other hand, has food provided 
for it, is sheltered, and often confined, to guard it against 
the vicissitudes of the seasons, is carefully secured from the 
attacks of its natural enemies, and seldom even rears its young 
without human assistance. Half of its senses and faculties 
become quite useless, and the other half are but occasionally 
called into feeble exercise, while even its muscular system is 
only irregularly brought into action. 

Now when a variety of such an animal occurs having 
increased power or capacity in any organ or sense, such 
increase is totally useless, is never called into action, and may 
even exist without the animal ever becoming aware of it. In 
the wild animal, on the contrary, all its faculties and powers 
being brought into full action for the necessities of existence, 
any increase becomes immediately available, is strengthened 
by exercise, and must even slightly modify the food, the habits, 
and the whole economy of the race. It creates as it were a 
new animal, one of superior powers, and which will necessarily 
increase in numbers and outlive those which are inferior to it. 

Again, in the domesticated animal all variations have an 
equal chance of continuance ; and those which would de- 
cidedly render a wild animal unable to compete with its 
fellows and ' continue its existence are no disadvantage what- 



IJ ON THE TENDENCY OF VARIETIES, ETC. 31 

ever in a state of domesticity. "Our quickly fattening pigs, 
short -legged sheep, pouter pigeons, and poodle dogs could 
never have come into existence in a state of nature, because 
the very first steps towards such inferior forms would have 
led to the rapid extinction of the race ; still less could they 
now exist in competition with their wild allies. The great 
speed but slight endurance of the racehorse, the unwieldly 
strength of the ploughman's team, would both be useless in 
a state of nature. If turned wild on the pampas, sach 
animals would probably soon become extinct, or under 
favourable circumstances might each gradually lose those 
extreme qualities which would never be called into action, 
and in a few generations revert to a common type, which 
must be that in which the various powers and faculties are so 
proportioned to each other as to be best adapted to procure 
food and secure safety, — that in which, by the full exercise of 
every part of its organisation, the animal can alone continue 
to live. Domestic varieties, when turned wild, must return 
to something near the type of the original wild stock, or 
become altogether extinct.^ 

We see, then, that no inferences as to the permanence of 
varieties in a state of nature can be deduced from the ob- 
servations of those occurring among domestic animals. The 
two are so much opposed to each other in every circumstance- 
of their existence, that what applies to the one is almost sure 
not to apply to the other. Domestic animals are abnormal, 
irregular, artificial ; they are subject to variations which 
never occur, and never can occur, in a state of nature : their 
very existence depends altogether on human care — so far are 
many of them removed from that just proportion of faculties, 
that true balance of organisation, by means of which alone an 
animal left to its own resources can preserve its existence and 
continue its race. 

Lamarck's Hypothesis very different from that now advanced 
The hj^othesis of Lamarck — that progressive changes in 
species have been produced by the attempts of animals to 

* That is, they will vary, and the variations which tend to adapt them to 
the wild state, and therefore approximate them to wild animals, will be pre- 
served. Those individuals which do not vary sufficiently will perish. 



32 NATURAL SELECTION ii 

increase the development of their own organs, and thus 
modify their structure and habits — has been repeatedly and 
easily refuted by all writers on the subject of varieties and 
species, and it seems to have been considered that when this 
was done the whole question has been finally settled ; but 
the view here developed renders such an hypothesis quite 
unnecessary, by showing that similar results must be pro- 
duced by the action of principles constantly at work in 
nature. The powerful retractile talons of the falcon and 
the cat tribes have not been produced or increased by the 
volition of those animals ; but among the different varieties 
which occurred in the earlier and less highly organised forms 
of these groups, those always survived longest which had the 
greatest facilities for seizing their prey. Neither did the 
giraffe acquire its long neck by desiring to reach the foliage 
of the more lofty shrubs, and constantly stretching its neck 
for the purpose, but because any varieties which occurred 
among its antitypes with a longer neck than usual at once 
secwred a fresh range of pasture over the same ground as their 
shorter-necked companions, and on the fvrst scarcity of food were 
thereby enabled to outlive them. Even the peculiar colours of 
many animals, more especially of insects, so closely resem- 
bling the soil or leaves or bark on which they habitually 
reside, are explained on the same principle ; for though in 
the course of ages varieties of many tints may have occurred, 
yet those races having colowrs best adapted to concealment from their 
enemies would inevitably survive the longest. We have also 
here an acting cause to account for that balance so often 
observed in nature, — a deficiency in one set of organs always 
being compensated by an increased development of some 
others — powerful wings accompanying weak feet, or great 
velocity making up for the absence of defensive weapons ; 
for it has been shown that all varieties in which an un- 
balanced deficiency occurred could not long continue their 
existence. The action of this principle is exactly like that 
of the centrifugal governor of the steam-engine, which checks 
and corrects any irregularities almost before they become 
evident ; and in like manner no unbalanced deficiency in the 
animal kingdom can ever reach any conspicuous magnitude, 
because it would make itself felt at the very first step, by 



II ON THE TENDENCY OF VARIETIES, ETC. 33 

rendering existence difficult and extinction almost sure soon 
to follow. An origin such as is here advocated will also 
agree with the peculiar character of the modifications of form 
and structure which obtain in organised beings — the many 
lines of divergence from a central type, the increasing effici- 
ency and power of a particular organ through a succession of 
aUied species, and the remarkable persistence of unimportant 
parts, such as colour, texture of plumage and hair, form of 
horns or crests, through a series of species differing consider- 
ably in more essential characters. It also furnishes us with 
a reason for that " more speciaKsed structure " which Pro- 
fessor Owen states to be a characteristic of recent compared 
with extinct forms, and which would evidently be the result 
of the progressive modification of any organ applied to a 
special purpose in the animal economy. 

Conclusion 

We believe we have now shown that there is a tendency 
in nature to the continued progression of certain classes of 
varieties further and further from the original type — a pro- 
gression to which there appears no reason to assign any 
definite limits — and that the same principle which produces 
this result in a state of nature will also explain why domestic 
varieties have a tendency, when they become wild, to revert 
to the original type. This progression, by minute steps, in 
various directions, but always checked and balanced by the 
necessary conditions, subject to which alone existence can be 
preserved, may, it is believed, be followed out so as to 
agree with all the phenomena presented by organised 
beings, their extinction and succession in past ages, and all 
the extraordinary modifications of form, instinct, and habits 
which they exhibit. 



HI 

MIMICRY, AND OTHER PROTECTIVE RESEMBLANCES AMONG 
ANIMALS ^ 

There is no more convincing proof of the truth of a com- 
prehensive theory than its povrer of absorbing and finding 
a place for new facts, and its capability of interpreting 
phenomena which had been previously looked upon as un- 
accountable anomalies. It is thus that the law of universal 
gravitation and the undulatory theory of light have become 
established and universally accepted by men of science. 
Fact after fact has been brought forward as being apparently 
inconsistent with them, and one after another these very 
facts have been shown to be the consequences of the laws 
they were at first supposed to disprove. A false theory will 
never stand this test. Advancing knowledge brings to light 
whole groups of facts which it cannot deal with, and its 
advocates steadily decrease in numbers, notwithstanding the 
ability and scientific skill with which it may have been 
supported. The great name of Edward ■ Forbes did not 
prevent his theory of " Polarity in the distribution of Organic 
beings in Time " from dying a natural death ; but the most 
striking illustration of the behaviour of a false theory is to 
be found in the " Circular and Quinarian System " of classi- 
fication propounded by MacLeay, and developed by Swain- 
son, with an amount of knowledge and ingenuity that has 
rarely been surpassed. This theory was eminently attract- 
ive, both from its symmetry and completeness, and from 
the interesting nature of the varied analogies and affinities 

^ First published in the Westminster Review, July 1867 ; reprinted in 
1870 with additions and corrections. 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 35 

which it brought to light and made use of. The series of 
Natural History volumes in Lardnei's Oabimet Cydopcedia, in 
which Mr. Swainson developed it in most departments of the 
animal kingdom, made it widely known ; and in fact for a 
long time these were the best and almost the only popular 
text-books for the rising generation of naturalists. It was 
favourably received too by the older school/ which was per- 
haps rather an indication of its unsoundness. A considerable 
number of well-known naturalists either spoke approvingly of 
it, or advocated similar principles, and for a good many years 
it was decidedly in the ascendant. With such a favourable 
introduction, and with such talented exponents, it must have 
become established if it had had any germ of truth in it ; 
yet it quite died out in a few short years ; its very existence 
is now a matter of history ; and so rapid was its fall that 
its talented creator, Swainson, perhaps lived to be the last 
man who believed in it. , 

Such is the course of a false theory. That of a true one 
is very different, as may be well seen by the progress of 
opinion on the subject of Natural Selection. In less than 
eight years The Origin of Species has produced conviction 
in the minds of a majority of the most eminent living men 
of science. New facts, new problems, new difficulties as they 
arise are accepted, solved, or removed by this theory ; and its 
principles are illustrated by the progress and conclusions of 
every well established branch of human knowledge. It is the 
object of the present chapter to show how it has recently been 
applied to connect together and explain a variety of curious 
facts which had long been considered as inexplicable anomalies. 

Importance of the Principle of Utility 

Perhaps no principle has ever been announced so fertile in 
results as that which Mr. Darwin so earnestly impresses upon 
us, and which is indeed a necessary deduction from the 
theory of Natural Selection, namely — that none of the 
definite facts or organic nature, no special organ, no char- 
acteristic form of marking, no peculiarities of instinct or of 
habit, no relations between species or between groups of 
species — can exist, but which must now be or once have been 
useful to the individuals or the races which possess them. 



36 NATURAL SELECTION ni 

This great principle gives us a clue which we can follow out 
in the study of many recondite phenomena, and leads us to 
seek a meaning and a purpose of some definite character in 
minutiae which we should otherwise be almost sure to pass 
over as insignificant or unimportant. 

Popular Theories of Colour in Animals 
The adaptation of the external colouring of animals to 
their conditions of life has long been recognised, and has been 
imputed either to an originally created specific peculiarity, 
or to the direct action of climate, soil, or food. "Where the 
former explanation has been accepted it has completely 
checked inquiry, since we could never get any further than 
the fact of the adaptation. There was nothing more to be 
known about the matter. The second explanation was soon 
found to be quite inadequate to deal with all the varied 
phases of the phenomena, and to be contradicted by many 
well known facts. For example, wild rabbits are always of 
gray or brown tints well suited for concealment among grass 
and fern. But when these rabbits are domesticated, without 
any change of climate or food, they vary into white or black, 
and these varieties may be multiplied to any extent, forming 
white or black races. Exactly the same thing has occurred 
with pigeons ; and in the case of rats and mice, the white 
variety has not been shown to be at all dependent on altera- 
tion of climate, food, or other external conditions. In many 
cases the wings of an insect not only assume the exact tint of 
the bark or leaf it is accustomed to rest on, but the form and 
veining of the leaf or the exact rugosity of the bark is 
imitated ; and these detailed modifications cannot be reason- 
ably imputed to climate or to food, since in many cases the 
species does not feed on the substance it resembles, and when 
it does, no reasonable connection can be shown to exist 
between the supposed cause and the effect produced. It was 
reserved for the theory of Natural Selection to solve aU these 
problems, and many others which were not at first supposed 
to be directly connected with them. To make these latter 
intelligible, it will be necessary to give a sketch of the whole 
series of phenomena which may be classed under the head of 
useful or protective resemblances. 



in PROTECTIVE RESEMBLANCES AMONG ANIMALS 37 



Importance of Concealment as Influencing Colmr 

Concealment, more or less complete, is useful to many 
animals, and absolutely essential to some. Those which have 
numerous enemies from -which they cannot escape by rapidity 
of motion find safety in concealment. Those which prey 
upon others must also be so constituted as not to alarm them 
by their presence or their approach, or they would soon die 
of hunger. Now it is remarkable in how many cases nature 
gives this boon to the animal, by colouring it with such tints 
as may best serve to enable it to escape from its enemies or 
to entrap its prey. Desert animals as a rule are desert- 
coloured. The lion is a typical example of this, and must be 
almost invisible when crouched upon the sand or among 
desert rocks and stones. Antelopes are all more or less 
sandy-coloured. The camel is pre-eminently so. The 
Egyptian cat and the Pampas cat are sandy or earth-coloiu'ed. 
The Australian kangaroos are of the same tints, and the 
original colour of the wild horse is supposed to have been a 
sandy or clay-colour. 

The desert birds are still more remarkably protected by 
their assimilative hues. The stonechats, the larks, the quails, 
the goatsuckers and the grouse, which abound in the North 
African and Asiatic deserts, are all tinted and mottled so as 
to resemble with wonderful accuracy the average colour and 
aspect of the soU in the district they inhabit. The Eev. H. 
Tristram, in his account of the ornithology of North Africa 
in the first volume of the Ibis, says : " In the desert, where 
neither trees, brushwood, nor even undulation of the surface 
afibrd the slightest protection to its foes, a modification of 
colour which shall be assimilated to that of the surrounding 
country is absolutely necessary. Hence without exception the 
upper plumage of every bird, whether lark, chat, sylvain, or 
sand-grouse, and also the fur of all the smaller mammals, and 
the skin of all the snakes and lizards, is of one uniform isabelline 
or sand colour." After the testimony of so able an observer 
it is unnecessary to adduce further examples of the protective 
colours of desert animals. 

Almost equally striking are the cases of arctic animals 
possessing the white colour that best conceals them upon 



NATURAL SELECTION 



snowfields and icebergs. The polar bear is the only bear 
that is white, and it lives constantly among snow and ice. 
The arctic fox, the ermine, and the alpine hare change to 
white in winter only, because in summer white would be 
more conspicuous than any other colour, and therefore a 
danger rather than a protection; but the American polar 
hare, inhabiting regions of almost perpetual snow, is white all 
the year round. Other animals inhabiting the same Northern 
regions do not, however, change colour. The sable is a good 
example, for throughout the severity of a Siberian winter it 
retains its rich brown fur. But its habits are such that it 
does not need the protection of colour, for it is said to be able 
to subsist on fruits and berries in winter, and to be so active 
upon the trees as to catch small birds among the branches. 
So also the woodchuck of Canada has a dark-brown fur ; but 
then it lives in burrows and frequents river banks, catching 
fish and small animals that live in or near the water. 

Among birds, the ptarmigan is a fine example of protective 
colouring. Its summer plumage so exactly harmonises with 
the lichen-coloured stones among which it delights to sit, that 
a person may walk through a flock of them without seeing a 
single bird ; while in winter its white plumage is an almost 
equal protection. The snow-bunting, the jer-falcon, and the 
snowy owl are also white-coloured birds inhabiting the arctic 
regions, and there can be little doubt but that their colouring 
is to some extent protective. 

Nocturnal animals supply us with equally good illustrations. 
Mice, rats, bats and moles possess the least conspicuous of 
hues, and must be quite invisible at times when any light 
colour would be instantly seen. Owls and goatsuckers are of 
those dark mottled tints that will assimilate with bark and 
lichen, and thus protect them during the day, and at the 
same time be inconspicuous in the dusk. 

It is only in the tropics, among forests which never lose 
their foliage, that we find whole groups of birds whose chief 
colour is green. The parrots are the most striking example, 
but we have also a group of green pigeons in the East ; and 
the barbets, leaf-thrushes, bee-eaters, white-eyes, turacos, and 
several smaller groups, have so much green in their plumage 
as to tend greatly to conceal them among the foliage. 



ni PROTECTIVE RESEMBLANCES AMONG ANIMALS 39 



Special Modifications of Colowr 

The conformity of tint which has been so far shown to 
exist between animals and their habitations is of a somewhat 
general character; we will now consider the cases of more 
special adaptation. If the lion is enabled by his sandy 
colour readily to conceal himself by merely crouching down 
upon the desert, how, it may be asked, do the elegant markings 
of the tiger, the jaguar, and the other large cats, agree 
with this theory 1 We reply that these are generally cases 
of more or less special adaptation. The tiger is a jungle 
animal, and hides himself among tufts of grass or of bamboos, 
and in these positions the vertical stripes with which his 
body is adorned must so assimilate with the vertical stems of 
the bamboo as to assist greatly in concealing him from his 
approaching prey.^ How remarkable it is that besides the 
lion and tiger, almost all the other large cats are arboreal in 
their habits, and almost all have ocellated or spotted skins, 
which must certainly tend to blend them with the background 
of foliage; while the one exception, the puma, has an ashy 
brown uniform fur, and has the habit of clinging so closely 
to a limb of a tree while waiting for his prey to pass beneath 
as to be hardly distinguishable from the bark. 

Among birds, the ptarmigan, already mentioned, must be 
considered a remarkable case of special adaptation. Another 
is a South American goatsucker (Caprimulgus rupestris), which 
rests in the bright sunshine on little bare rocky islets in the 
Upper Eio Negro, where its unusually light colours so closely 
resemble those of the rock and sand that it can scarcely be 
detected till trodden upon. 

The Duke of Argyll, in his Beign of Law, has pointed out 
the admirable adaptation of the colours of the woodcock to 
its protection. The various browns and yellows and pale 
ash-colour that occur in fallen leaves are all reproduced in its 
plumage, so that when, according to its habit, it rests upon 
the ground under trees, it is almost impossible to detect it. 
In snipes the colours are modified so as to be equally in 
harmony with the prevalent forms and colours of marshy 
vegetation. Mr. J. M. Lester, in a paper read before the 

' This suggestion has been since confirmed. See Darwinism, p. 199. 



40 NATURAL SELECTION iti 

Rugby School Natural History Society, observes : " The 
wood-dove, when perched amongst the branches of its favour- 
ite fir, is scarcely discernible ; whereas, were it among some 
lighter foliage, the blue and purple tints in its plumage would 
far sooner betray it. The robin redbreast too, although it 
might be thought that the red on its breast made it much 
easier to be seen, is in reality not at all endangered by it, 
since it generally contrives to get among some russet or 
yellow fading leaves, where the red matches very well with 
the autumn tints, and the brown of the rest of the body with 
the bare branches." 

Reptiles offer us many similar examples. The most 
arboreal lizards, the iguanas, are as green as the leaves they 
feed upon, and the slender whip-snakes are rendered almost 
invisible as they glide among the foliage by a similar color- 
ation. How diflScult it is sometimes to catch sight of the 
little green tree-frogs sitting on the leaves of a small plant 
enclosed in a glass case in the Zoological Gardens ; yet how 
much better concealed must they be among the fresh green 
damp foliage of a marshy forest. There is a North American 
frog found on lichen -covered rocks and walls, which is so 
coloured as exactly to resemble them, and as long as it 
remains quiet would certainly escape detection. Some of the 
geckos which cling motionless on the trunks of trees in the 
tropics are of such curiously marbled colours as to match 
exactly with the bark they rest upon. 

In every part of the tropics there are tree-snakes that 
twist among boughs and shrubs, or lie coiled up on the dense 
masses of foliage. These are of many distinct groups, and 
comprise both venomous and harmless genera ; but almost all 
of them are of a beautiful green colour, sometimes more or 
less adorned with white or dusky bands and spots. There 
can be little doubt that this colour is doubly useful to them, 
since it will tend to conceal them from their enemies, and 
will lead their prey to approach them unconscious of danger. 
Dr. Gunther informs me that there is only one genus of true 
arboreal snakes (Dipsas) whose colours are rarely green, but 
are of various shades of black, brown, and olive, and these 
are all nocturnal reptiles, and there can be little doubt 
conceal themselves during the day in holes, so that the green 



in PROTECTIVE RESEMBLANCES AMONG ANIMALS 41 

protective tint would be useless to them, and they accordingly 
retain the more usual reptilian hues. 

Fishes present similar instances. Many flat fish, as for 
example the flounder and the skate, are exactly the colour of 
the gravel or sand on which they habitually rest. Among 
the marine flower gardens of an Eastern coral reef the fishes 
present every variety of gorgeous colour, while the river fish 
even of the tropics rarely if ever have gay or conspicuous 
markings. A very curious case of this kind of adaptation 
occurs in the sea-horses (Hippocampus) of Australia, some of 
which bear long foliaceous appendages resembling seaweed, 
and are of a brilliant red colour ; and they are known to live 
among seaweed of the same hue, so that when at rest they 
must be quite invisible. There are now in the aquarium of 
the Zoological Society some slender green pipe-fish which 
fasten themselves to any object at the bottom by their 
prehensile tails, and float about with the current, looking 
exactly Hke some simple cylindrical algse. 

It is, however, in the insect world that this principle of 
the adaptation of animals to their environment is most fully 
and strikingly developed. In order to understand how 
general this is, it is necessary to enter somewhat into details, 
as we shall thereby be better able to appreciate the signifi- 
cance of the still more remarkable phenomena we shall 
presently have to discuss. It seems to be in proportion to 
their sluggish motions or the absence of other means of 
defence, that insects possess the protective colouring. In the 
tropics there are thousands of species of insects which rest 
during the day clinging to the bark of dead or fallen trees ; 
and the greater portion of these are delicately mottled with 
gray and brown tints, which, though symmetrically disposed 
and infinitely varied, yet blend so completely with the usual 
colours of the bark, that at two or three feet distance^ they 
are quite undistinguishable. In some cases a species is 
known to frequent only one species of tree. This is the case 
with the common South American long -horned beetle 
(Onychocerus scorpio), which, Mr. Bates informed me, is 
found only on a rough-barked tree, called Tapiribd, on the 
Amazon. It is very abundant, but so exactly does it resemble 
the bark in colour and rugosity, and so closely does it cling 



42 NATURAL SELECTION in 

to tlie branches, that until it moves it is absolutely invisible ! 
An allied species (0. concentricus) is found only at Pari, on a 
distinct species of tree, the bark of which it resembles with 
equal accuracy. Both these insects are abundant, and we 
may fairly conclude that the protection they derive from this 
strange concealment is at least one of the causes that enable 
the race to flourish. 

Many of the species of Cicindela, or tiger beetle, will 
illustrate this mode of protection. Our common Cicindela 
campestris frequents grassy banks, and is of a beautiful green 
colour, while C. maritima, which is found only on sandy sea- 
shores, is of a pale bronzy yellow, so as to be almost invisible. 
A great number of the species found by myself in the Malay 
islands are similarly protected. The beautiful Cicindela 
gloriosa, of a very deep velvety green colour, was only taken 
upon wet mossy stones in the bed of a mountain stream, where 
it was with the greatest difficulty detected. A large brown 
species (0. heros) was found chiefly on dead leaves in forest 
paths ; and one which was never seen except on the wet mud 
of salt marshes was of a glossy olive so exactly the colour of the 
mud as only to be distinguished, when the sun shone, by its 
shadow ! Where the sandy beach was coralline and nearly 
white, I found a very pale Cicindela ; wherever it was volcanic 
and black, a dark species of the same genus was sure to be 
met with. 

There are in the East small beetles of the family Bupres- 
tidae which generally rest on the midrib of a leaf, and the 
naturalist often hesitates before picking them off, so closely 
do they resemble pieces of bird's dung. Kirby and Spence 
mention the small beetle Onthophilus sulcatus as being like 
the seed of an umbelliferous plant; and another, a small 
weevil, which is much persecuted by predatory beetles of the 
genus Harpalus, is of the exact colour of loamy soil, and was 
found to be particularly abundant in loam pits. Mr. Bates 
mentions a small beetle (Chlamys pilula) which was undis- 
tinguishable by the eye from the dung of caterpillars, while 
some of the Cassidse, from their hemispherical forms and pearly 
gold colour, resemble glittering dew-drops upon the leaves. 

A number of our small brown and speckled weevils at the 
approach of any object roll off the leaf they are sitting on, at 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 43 



the same time drawing in their legs and antennae, which fit so 
perfectly into cavities for their reception that the insect 
becomes a mere oval brownish lump, which it is hopeless to 
look for among the similarly coloured little stones and earth 
pellets among which it Hes motionless. 

The distribution of colour in butterflies and moths re- 
spectively is very instructive from this point of view. The 
former have all their brilliant colouring on the upper surface 
of all four wings, while the under surface is almost always 
soberly coloured, and often very dark and obscure. The 
moths on the contrary have generally their chief colour on 
the hind wings only, the upper wings being of dull, sombre, 
and often imitative tints, and these generally conceal the 
hind wings when the insects are in repose. This arrange- 
ment of the colours is therefore eminently protective, because 
the butterfly always rests with his wings raised so as to con- 
ceal the dangerous brilliancy of his upper surface. It is 
probable that if we watched their habits sufficiently we should 
find the under surface of the wings of butterflies very fre- 
quently imitative and protective. Mr. T. W. Wood has 
pointed out that the little orange-tip butterfly often rests in 
the evening on the green and white flower heads of an 
umbelliferous plant, the wild chervil,^ and that when observed 
in this position the beautiful green and white mottling of the 
under surface completely assimilates with the flower heads 
and renders the creature very difficult to be seen. It is 
probable that the rich dark colouring of the under side of our 
peacock, tortoiseshell, and red-admiral butterflies answers a 
similar purpose. 

Two curious South American butterflies that always settle 
on the trunks of trees (Gynecia dirce and CalUzona acesta) 
have the under surface curiously striped and mottled, and 
when viewed obliquely must closely assimilate with the appear- 
ance of the furrowed bark of many kinds of trees. But the most 
wonderful and undoubted case of protective resemblance in a 
butterfly which I have ever seen, is that of the common Indian 
Kallima inachis, and its Malayan ally, Kallima paralekta. 
The upper surface of these insects is very striking and showy, 
as they are of a large size, and are adorned with a broad band 
^ Anthriscus sylvestris. 



44 NATURAL SELECTION in 

of rich orange on a deep-bluish ground. The under side is 
very variable in colour, so that out of fifty specimens no two 
can be found exactly alike, but every one of them will be of 
some shade of ash or brown or ochre, such as are found 
among dead; dry, or decaying leaves. The apex of the upper 
wings is produced into an acute point, a very common form 
in the leaves of tropical shrubs and trees, and the lower 
wings are also produced into a short narrow tail. Between 
these two points runs a dark curved line exactly representing 
the midrib of a leaf, and from this radiate on each side a few 
oblique lines, which serve to indicate the lateral veins of a 
leaf. These marks are more clearly seen on the outer por- 
tion of the base of the wings, and on the inner side towards 
the middle and apex, and it is very curious to observe how 
the usual marginal and transverse striae of the group are here 
modified and strengthened so as to become adapted for an 
imitation of the venation of a leaf. We come now to a still more 
extraordinary part of the imitation, for we find representations 
of leaves in every stage of decay, variously blotched and mil- 
dewed and pierced with holes, and in many cases irregularly 
covered with powdery black dots gathered into patches andspots, 
so closely resembling the various kinds of minute fungi that 
grow on dead leaves that it is impossible to avoid thinking at 
first sight that the butterflies themselves have been attacked 
by real fungi. 

But this resemblance, close as it is, would be of little use 
if the habits of the insect did not accord with it. If the 
butterfly sat upon leaves or upon flowers, or opened its wings 
so as to expose the upper surface, or exposed and moved its 
head and antennse as many other butterflies do, its disguise 
would be of little avail. We might be sure, however, from 
the analogy of many other cases, that the habits of the insect 
are such as still further to aid its deceptive garb ; but we are 
not obliged to make any such supposition, since I myself had 
the good fortune to observe scores of Kallima paralekta, in 
Sumatra, and to capture many of them, and can vouch for the 
accuracy of the following details. The?e butterflies frequent 
dry forests and fly very swiftly. They were never seen to 
settle on a flower or a green leaf, but were many times lost 
sight of in a bush or tree of dead leaves. On such occasions 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 45 

they were generally searched for in vain, for while gazing 
intently at the very spot where one had disappeared, it would 
often suddenly dart out, and again vanish twenty or fifty 
yards farther on. On one or two occasions the insect was 
detected reposing, and it could then be seen how completely 
it assimilates itself to the surrounding leaves. It sits on a 
nearly upright twig, the wings fitting closely back to back, 
concealing the antennae and head, which are drawn up between 
their bases. The little tails of the hind wing touch the 
branch, and form a perfect stalk to the leaf, which is sup- 
ported in its place by the claws of the middle pair of feet, 
which are slender and inconspicuous. The irregular outline of 
the wings gives exactly the perspective efiect of a shrivelled 
leaf. We thus have size, colour, form, markings, and habits 
all combining together to produce a disguise which may be 
said to be absolutely perfect ; and the protection which it 
affords is sufiiciently indicated by the abundance of the in- 
dividuals that possess it. 

The Eev. Joseph Greene has called attention to the strik- 
ing harmony between the colours of those British moths 
which are on the wing in autumn and winter, and the prevail- 
ing tints of nature at those seasons. In autumn various 
shades of yellow and brown prevail, and he shows that out of 
fifty-two species that fly at this season, no less than forty-two 
are of corresponding colours. Orgyia antiqua, 0. gonostigma, 
the genera Xanthia, Glsea, and Ennomos are examples. In 
winter, gray and silvery tints prevail, and the genus Chematobia 
and several species of Hybernia which fly during this season 
are of corresponding hues. No doubt if the habits of moths 
in a state of nature were more closely observed, we should 
find many cases of special protective resemblance. A few 
such have already been noticed. Agriopis aprilina, Acronycta 
psi, and many other moths which rest during the day on the 
north side of the trunks of trees, can with difficulty be dis- 
tinguished from the gray and green lichens that cover them. 
The lappet moth (Gastropacha querci) closely resembles both 
in shape and colour a brown dry leaf ; and the well-known 
buff-tip moth, when at rest, is Hke the broken end of a lichen- 
covered branch. There are some of the small moths which 
exactly resemble the dung of birds dropped on leaves, and on 



46 NATURAL SELECTION in 

this point Mr. A. Sidgwick, in a paper read before the Eugby 
School Natural History Society, gives the following original 
observation : "I myself have more than once mistaken Cilix 
compressa, a little white and gray moth, for a piece of bird's 
dung dropped upon a leaf, and vice versd the dung for the moth. 
Bryophila Glandifera and Perla are the very image of the 
mortar walls on which they rest ; and only this summer, in 
Switzerland, I amused myself for some time in watching a 
moth, probably Larentia tripunctaria, fluttering about quite 
close to me, and then alighting on a wall of the stone of the 
district which it so exactly matched as to be quite invisible a 
couple of yards off." There are probably hosts of these re- 
semblances which have not been observed, owing to the diffi- 
culty of finding many of the species in their stations of natural 
repose. Caterpillars are also similarly protected. Many 
exactly resemble in tint the leaves they feed upon ; others are 
like little brown twigs, and many are so strangely marked or 
humped, that when motionless they can hardly be taken to be 
living creatures at all. Mr. Andrew Murray has remarked 
how closely the larva of the peacock moth (Saturnia pavonia- 
minor) harmonises in its ground colour with that of the young 
buds of heather on which it feeds, and that the pink spots 
with which it is decorated correspond with the flowers and 
flower-buds of the same plant. 

The whole order of Orthoptera, grasshoppers, locusts, 
crickets, etc., are protected by their colours harmonising with 
that of the vegetation or the soil on which they Uve, and in 
no other group have we such striking examples of special 
resemblance. Most of the tropical Mantidse and Locustidse 
are of the exact tint of the leaves on which they habitually 
repose, and many of them in addition have the veinings of 
their wings modified so as exactly to imitate that of a leaf. 
This is carried to the furthest possible extent in the wonder- 
ful genus, Phyllium, the " walking leaf," in which not only 
are the wings perfect imitations of leaves in every detail, but 
the thorax and legs are flat, dilated, and leaf-like ; so that 
when the living insect is resting among the foliage on which 
it feeds, the closest observation is often unable to distinguish 
between the animal and the vegetable. 

The whole family of the Phasmidae, or spectres, to which 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 47 

this insect belongs, is more or less imitative, and a great 
number of tbe species are called " walking-stick insects," from 
their singular resemblance to twigs and branches. Some of 
these are a foot long and as thick as one's finger, and their 
whole colouring, form, rugosity, and the arrangement of the 
head, legs, and antennae are such as to render them absolutely 
identical in appearance with dead sticks. They hang loosely 
about shrubs in the forest, and have the extraordinary habit 
of stretching out their legs unsymmetrically, so as to render 
the deception more complete. One of these creatures ob- 
tained by myself in Borneo (Ceroxylus laceratus) was covered 
over with foHaceous excrescences of a clear olive green colour, 
so as exactly to resemble a stick grown over by a creeping 
moss or jungermannia. The Dyak who brought it me 
assured me it was grown over with moss although alive, and 
it was only after a most minute examination that I could 
convince myself it was not so. 

We need not adduce any more examples to show how 
important are the details of form and of colouring in animals, 
and that their very existence may often depend upon their 
being by these means concealed from their enemies. This 
kind of protection is found apparently in every class and 
order, for it has been noticed wherever we can obtain suffi- 
cient knowledge of the details of an animal's life-history. It 
varies in degree, from the mere absence of conspicuous colour 
or a general harmony with the prevailing tints of nature, up 
to such a minute and detailed resemblance to inorganic or 
vegetable structures as to realise the talisman of the fairy 
tale, and to give its possessor the power of rendering itself 
invisible. 

Theory of Protective Golowring 

We will now endeavour to show how these wonderful 
resemblances have most probably been brought about. Re- 
tui'ning to the higher animals, let us consider the remarkable 
fact of the rarity of white colouring in the mammalia or birds 
of the temperate or tropical zones in a state of nature. There 
is not a single white land-bird or quadruped in Europe, except 
the few arctic or alpine species, to which white is a protective 
colour. Yet in many of these creatures there seems to be no 



48 NATURAL SELECTION in 

inherent tendency to avoid white, for directly they are 
domesticated white varieties arise, and appear to thrive as 
well as others. We have white mice and rats, white cats, 
horses, dogs and cattle, white poultry, pigeons, turkeys and 
ducks, and white rabbits. Some of these animals have been 
domesticated for a long period, others only for a few centuries; 
but in almost every case in which an animal has been 
thoroughly domesticated, parti-coloured and white varieties 
are produced and become permanent. 

It is also well known that animals in a state of nature 
produce white varieties occasionally. Blackbirds, starlings, 
and crows are occasionally seen white, as well as elephants, 
deer, tigers, hares, moles, and many other animals ; but in 
no case is a permanent white race produced. Now there are 
no statistics to show that the normal-coloured parents produce 
white offspring oftener under domestication than in a state of 
nature, and we have no right to make such an assumption if 
the facts can be accounted for without it. But if the colours 
of animals do really, in the various instances already adduced, 
serve for their concealment and preservation, then white or 
any other conspicuous colour must be hurtful, and must in 
most cases shorten an animal's life. A white rabbit would' 
be more surely the prey of hawk or buzzard, and the white 
mole, or field mouse, could not long escape from the vigilant 
owl. So, also, any deviation from those tints best adapted 
to conceal a carnivorous animal would render the pursuit of 
its prey much more difiicult, would place it at a disadvantage 
among its fellows, and in a time of scarcity would probably 
cause it to starve to death. On the other hand, if an animal 
spreads from a temperate into an arctic district, the conditions 
are changed. During a large portion of the year, and just 
when the struggle for existence is most severe, white is the 
prevailing tint of nature, and dark colours vnll be the most 
conspicuous. The white varieties will now have an advan- 
tage ; they will escape from their enemies or will secure food, 
while their brown companions will be devoured or will starve; 
and as " like produces like " is the established rule in nature, 
the white race will become permanently established, and dark 
varieties, when they occasionally appear, will soon die out 
from their want of adaptation to their environment. In each 



iti PROTECTIVE RESEMBLANCilS AMONG ANIMALS 49 

case the fittest will survive, and a race will be eventually 
produced adapted to the conditions in which it lives. 

We have here an illustration of the simple and effectual 
means by which animals are brought into harmony vdth the 
rest of nature. That slight amount of variability in every 
species, which we often look upon as something accidental or 
abnormal, or so insignificant as to be hardly worthy of notice, 
is yet the foundation of all those wonderful and harmonious 
resemblances which play such an important part in the 
economy of nature. Variation is generally very small in 
amount,! but it is all that is required, because the change in 
the external conditions to which an animal is subject is 
generally very slow and intermittent. When these changes 
have taken place too rapidly, the result has often been the 
extinction of species ; but the general rule is, that climatal 
and geological changes go on slowly, and the slight but con- 
tinual variations in the colour, form, and structure of all 
animals have furnished individuals adapted to these changes, 
and who have become the progenitors of modified races. 
Eapid multiplication, incessant slight variation, and survival 
of the fittest — these are the laws which ever keep the organic 
world in harmony with the inorganic, and with itself. These 
are the laws which we believe have produced all the cases of 
protective resemblance already adduced, as well as those still 
more ciurious examples we have yet to bring before oiu- 
readers. 

It must always be borne in mind that the more wonderful 
examples, in which there is not only a general but a special 
resemblance — as in the walking leaf, the mossy phasma, and 
the leaf -winged butterfly — represent those few instances in 
which the process of modification has been going on during 
an immense series of generations. They all occur in the 
tropics, where the conditions of existence are the most 
favourable, and where climatic changes have for long periods 
been hardly perceptible. In most of them favourable varia- 
tions both of colour, form, structure, and instinct or habit, 
must have occurred to produce the perfect adaptation we now 
behold. All these are known to vary, and favourable varia- 

1 Later research has shown that variation is more frequent and of greater 
amount than at first supposed. See Darwinism, chap. iii. 

B 



So NATURAL SELECTIOlf til 

tions, when not accompanied by others that were unfavourable, 
would certainly survive. At one time a little step might be 
made in this direction, at .another time in that — a change of 
conditions might sometimes render useless that which it had 
taken ages to produce — great and sudden physical modifica- 
tions might often produce the extinction of a race just as it 
was approaching perfection, and a hundred checks of which 
we can know nothing may have retarded the progress towards 
perfect adaptation ; so that we can hardly wonder at there 
being so few cases in which a completely successful result has 
been attained as shown by the abundance and wide diffusion 
of the creatures so protected. 

Objection that Colour, as being dangerous, should not exist in 
Nature 

It is as well here to reply to an objection that will no 
doubt occur to many readers — that if concealment is so useful 
to all animals, and so easily brought about by variation and 
survival of the fittest, there ought to be no conspicuously- 
coloured creatures ; and they will perhaps ask how we 
account for the brilliant birds, and painted snakes, and 
gorgeous insects that occur abundantly all over the world. 
It will be advisable to answer this question rather fully, in 
order that we may be prepared to understand the phenomena 
of " mimicry," which it is the special object of this chapter to 
illustrate and explain. 

The slightest observation of the life of animals will show 
us that they escape from their enemies and obtain their food 
in an infinite number of ways, and that their varied habits 
and in.stincts are in every case adapted to the conditions of 
their existence. The porcupine and the hedgehog have a 
defensive armour that saves them from the attacks of most 
animals. The tortoise is not injured by the conspicuous 
colours of his shell, because that shell is in most cases an 
effectual protection to him. The skunks of North America 
find safety in their power of emitting an unbearably offensive 
odour ; the beaver in its aquatic habits and solidly constructed 
abode. In some cases the chief danger to an animal occurs 
at one particular period of its existence, and if that is guarded 
against its numbers can easily be maintained. This is the 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 51 



case with many birds, the eggs and young of which are 
especially obnoxious to danger, and we find accordingly a 
variety of curious contrivances to protect them. We have 
nests carefully concealed, hung from the slender extremities 
of grass or boughs over water, or placed in the hollow of a 
tree with a very small opening. When these precautions are 
successful, so many more individuals will be reared than can 
possibly find food during the least favourable seasons, that 
there will always be a number of weakly and inexperienced 
young birds who wOl fall a prey to the enemies of the race, 
and thus render necessary for the stronger and healthier 
individuals no other safeguard than their strength and activity. 
The instincts most favourable to the production and rearing 
of offspring will in these cases be most important, and the 
survival of the fittest will act so as to keep up and advance 
those instincts, while other causes which tend to modify 
colour and marking may continue their action almost un- 
checked. 

It is perhaps in insects that we may best study the varied 
means by which animals are defended or concealed. One of 
the uses of the phosphorescence with which many insects are 
furnished is probably to frighten away their enemies; for 
Kirby and Spence state that a ground-beetle (Carabus) has 
been observed running round and round a luminous centipede 
as if afraid to attack it. An immense number of insects have 
stings, and some stingless ants of the genus Polyrachis are 
armed with strong and sharp spines on the back, which must 
render them unpalatable to many of the smaller insectivorous 
birds. Many beetles of the family CurcuHonidae have the 
wing cases and other external parts so excessively hard, that 
they cannot be pinned without first drilling a hole to receive 
the pin, and it is probable that all such find a protection in 
this excessive hardness. Great numbers of insects hide them- 
selves among the petals of flowers, or in the cracks of bark 
and timber; and finally, extensive groups and even whole 
orders have a more or less powerful and disgusting smell and 
taste, which they either possess permanently, or can emit at 
pleasure. The attitudes of some insects may also protect 
them, as the habit of turning up the tail by the harmless 
rove-beetles (Staphylindidse) no doubt leads other animals 



52 NATURAL SELECTION 



besides children to the belief that they can sting. The 
curious attitude assumed by sphinx caterpillars is probably a 
safeguard, as well as the blood -red tentacles which can 
suddenly be thrown out from the neck by the caterpillars of 
all the true swallow-tailed butterflies. 

It is among the groups that possess some of these varied 
kinds of protection in a high degree that we find the greatest 
amount of conspicuous colour, or at least the most complete 
absence of protective imitation. The stinging Hymenoptera, 
wasps, bees, and hornets are, as a rule, very showy and 
brilliant insects, and there is not a single instance recorded 
in which any one of them is coloured so as to resemble a 
vegetable or inanimate substance. The Chrysididse, or golden 
wasps, which do not sting, possess as a substitute the power 
of rolling themselves up into a ball, which is almost as hard 
and polished as if really made of metal, — and they are all 
adorned with the most gorgeous colours.^ The whole order 
Hemiptera (comprising the bugs) emit a powerful odour, and 
they present a very large proportion of gay-coloured and con 
spicuous insects. The lady -birds (Coccinellidse) and their 
aUies the Eumorphidse, are often brightly spotted, as if to 
attract attention; but they can both emit fluids of a very 
disagreeable nature; they are certainly rejected by some birds 
and are probably never eaten by any. 

The great family of ground-beetles (Carabidse) almost all 
possess a disagreeable and some a very pungent smell, and a 
few, called bombardier beetles, have the peculiar faculty of 
emitting a jet of very volatile liquid, which appears like a 
puff of smoke, and is accompanied by a distinct crepitating 
explosion. It is probably because these insects are mostly 
nocturnal and predacious that they do not present more vivid 
hues. They are chiefly remarkable for brilliant metallic tints 
or dull red patches when they are not wholly black, and are 
therefore very conspicuous by day, when insect-eaters are 
kept off by their bad odour and taste, but are sufficiently 
invisible at night, when it is of importance that their prey 
should not become aware of their proximity. 

It seems probable that, in some cases, that which would 

^ These colours may, however, he protectire by causing the roUed-up insect 
to look like a piece of shining stone or mineral. 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 53 

appear at first to be a source of danger to its possessor may 
really be a means of protection. Many showy and weak- 
flying butterflies have a very broad expanse of wing, as in the 
brilliant blue Morphos of Brazilian forests, and the large 
Eastern Papilios ; yet these groups are tolerably plentiful. 
Now, specimens of these butterflies are often captured with 
pierced and broken wings, as if they had been seized by birds 
from whom they had escaped; but if the wings had been 
much smaller in proportion to the body, it seems probable 
that the insect would be more frequently struck or pierced in 
a vital part, and thus the increased expanse of the wings may 
have been indirectly beneficial. 

In other cases the capacity of increase in a species is so 
great that however many of the perfect insect may be de- 
stroyed, there is always ample means for the continuance of 
the race. Many of the flesh-flies, gnats, ants, palm-tree 
weevils, and locusts are in this category. The whole family 
of Cetoniadse or rose chafers, so full of gaily-coloured species, 
are probably saved from attack by a combination of char- 
acters. They fly very rapidly with a zigzag or waving 
course ; they hide themselves the moment they alight, either 
in the corolla of flowers, or in rotten wood, or in cracks and 
hollows of trees, and they are generally encased in a very 
hard and polished coat of maU, which may render them un- 
satisfactory food to such birds as would be able to capture 
them. The causes which lead to the development of colour 
have been here able to act unchecked, and we see the result 
in a large variety of the most gorgeously-coloured insects. 

Here, then, with our very imperfect knowledge of the 
life-history of animals, we are able to see that there are 
widely varied modes by which they may obtain protection 
from their enemies or concealment from their prey. Some of 
these seem to be so complete and effectual as to answer all the 
wants of the race, and lead to the maintenance of the largest 
possible population. When this is the case, we can well under- 
stand that no further protection derived from a modification 
of colour can be of the slightest use, and the most brilliant 
hues may be developed without any prejudicial eff'ect upon 
the species. On some of the laws that determine the de- 
velopment of colour something may be said presently. It is 



54 NATURAL SELECTION m 

now merely necessary to show that concealment by obscure 
or imitative tints is only one out of very many ways by which 
animals maintain their existence ; and having done this we 
are prepared to consider the phenomena of what has been 
termed "mimicry." It is to be particularly observed, how- 
ever, that the word is not here used in the sense of voluntary 
imitation, but to imply a particular kind of resemblance — 
a resemblance not in internal structure but in external 
appearance — a resemblance in those parts only that catch 
the eye — a resemblance that deceives. As this kind of 
resemblance has the same effect as voluntary imitation or 
mimicry, and as we have no word that expresses the required 
meaning, " mimicry " was adopted by Mr. Bates (who was the 
first to explain the facts), and has led to some misunder- 
standing; but there need be none, if it is remembered 
that both " mimicry " and " imitation " are used in a meta- 
phorical sense, as implying that close external likeness which 
causes things unlike in structure to be mistaken for each 
other. 

Mimicry 

It has been long known to entomologists that certain 
insects bear a strange external resemblance to others belong- 
ing to distinct genera, families, or even orders, and with 
which they have no real affinity whatever. The fact, how- 
ever, appears to have been generally considered as dependent 
upon some unknown law of "analogy" — some "system of 
nature," or " general plan," which had guided the Creator in 
designing the myriads of insect forms, and which we could 
never hope to understand. In only one case does it appear 
that the resemblance was thought to be useful, and to have 
been designed as a means to a definite and intelligible pur- 
pose. The flies of the genus Volucella enter the nests of bees 
to deposit their eggs, so that their larvae may feed upon the 
larvse of the bees, and these flies are each wonderfully like 
the bee on which it is parasitic. Kirby and Spence believed 
that this resemblance or " mimicry " was for the express pur- 
pose of protecting the flies from the attacks of the bees, and 
the connection is so evident that it was hardly possible to 
avoid this conclusion. The resemblance, however, of moths 



Ill PEOTECTIVE RESEMBLANCES AMONG ANIMALS 55 

to butterflies or to bees, of beetles to wasps, and of locusts to 
beetles, has been many times noticed by eminent writers ; 
but scarcely ever till within the last few years does it appear 
to have been considered that these resemblances had any 
special purpose, or were of any direct benefit to the insects 
themselves. In this respect they were looked upon as 
accidental, as instances of the " curious analogies " in nature 
which must be wondered at but which could not be explained. 
Recently, however, these instances have been greatly multi- 
plied ; the nature of the resemblances has been more carefully 
studied, and it has been found that they are often carried out 
into such details as almost to imply a purpose of deceiving 
the observer. The phenomena, moreover, have been shown 
to follow certain definite laws, which again all indicate their 
dependence on the more general law of the " survival of the 
fittest," or, " the preservation of favoured races in the struggle 
for life." It will, perhaps, be as well here to state what these 
laws or general conclusions are, and then to give some account 
of the facts which support them. 

The first law is, that in an overwhelming majority of cases 
of mimicry, the animals (or the groups) which resemble each 
other inhabit the same country, the same district, and in 
most cases are to be found together on the very same spot. 

The second law is, that these resemblances are not indis- 
criminate, but are limited to certain groups, which in every 
case are abundant in species and individuals, and can often 
be ascertained to have some special protection. 

The third law is, that the species which resemble or 
" mimic " these dominant groups are comparatively less 
abundant in individuals, and are often very rare. 

These laws wQl be found to hold good in aU the cases of 
true mimicry among various classes of animals to which we 
have now to call the attention of our readers. 

Mimicry among Lepidoptera 

As it is among butterflies that instances of mimicry are 
most numerous and most striking, an account of some of the 
more prominent examples in this group will first be given. 
There is in South America an extensive family of these 
insects, the Heliconidse, which are in many respects very 



56 NATURAL SELECTION in 

remarkable. They are so abundant and characteristic in 
all the woody portions of the American tropics, that in 
almost every locality they will be seen more frequently than 
any other butterflies. They are distinguished by very elon- 
gate wings, body, and antennae, and are exceedingly beautiful 
and varied in their colours ; spots and patches of yeUow, red, 
or pure white upon a black, blue, or brown ground being 
most general. They frequent the forests chiefly, and all fly 
slowly and weakly ; yet although they are so conspicuous, 
and could certainly be caught by insectivorous birds more 
easily than almost any other insects, their great abundance 
all over the wide region they inhabit shows that they are not 
so persecuted. It is to be especially remarked also, that they 
possess no adaptive colouring to protect them during repose, 
for the under side of their wings presents the same, or at least 
an equally conspicuous colouring as the upper side ; and they 
may be observed after sunset suspended at the end of twigs 
and leaves, where they have taken up their station for the 
night, fully exposed to the attacks of enemies if they have 
any. These beautiful insects possess, however, a strong 
pungent semi-aromatic or medicinal odour, which seems to 
pervade all the juices of their system. When the entomolo- 
gist squeezes the breast of one of them between his fingers to 
kill it, a yellow liquid exudes which stains the skin, and the 
smell of which can only be got rid of by time and repeated 
washings. Here we have probably the cause of their im- 
munity from attack, since there is a great deal of evidence to 
show that certain insects are so disgusting to birds that they 
will under no circumstances touch them. Mr. Stainton has 
observed that a brood of young turkeys greedily devoured all 
the worthless moths he had amassed in a night's " sugaring," 
yet one after another seized and rejected a single white moth 
which happened to be among them. Young pheasants and 
partridges which eat many kinds of caterpillars seem to have 
an absolute dread of that of the common currant moth, which 
they will never touch, and tomtits as well as other small birds 
appear never to eat the same species. In the case of the 
Heliconidae, however, we have some direct evidence to the 
same effect. In the Brazilian forests there are great numbers 
of insectivorous birds — as jacamars, trogons, and puff birds — 



in PROTECTIVE RESEMBLANCES AMONG ANIMALS 57 

which catch insects on the wing, and that they destroy many 
butterflies is indicated by the fact that the wings of these 
insects are often found on the ground where their bodies 
have been devoured. But among these there are no wings of 
Heliconidse, while those of the large showy Nymphalidse, 
which have a much swifter flight, are often met with. Again, 
a gentleman who had recently returned from Brazil stated at 
a meeting of the Entomological Society that he once observed 
a pair of puffbirds catching butterflies, which they brought to 
their nest to feed their young ; yet during half an hour they 
never brought one of the HeliconidEe, which were flying lazily 
about in great numbers, and which they could have captured 
more easily than any others. It was this circumstance that 
led Mr. Belt to observe them so long, as he could not under- 
stand why the most common insects should be altogether 
passed by. Mr. Bates also tells us that he never saw them 
molested by lizards or predacious flies, which often pounce on 
other butterflies. 

If, therefore, we accept it as highly probable (if not proved) 
that the Heliconidse are very greatly protected from attack by 
their peciiliar odour and taste, we find it much more easy to 
understand their chief characteristics — their great abundance, 
their slow flight, their gaudy colours, and the entire absence 
of protective tints on their under surfaces. This property 
places them somewhat in the position of those curious wingless 
birds of oceanic islands, the dodo, the apteryx, and the moas, 
which are with great reason supposed to have lost the power 
of flight on account of the absence of carnivorous quadrupeds. 
Our butterflies have been protected in a difierent way, but 
quite as eff'ectually; and the result has been that as there has 
been nothing to escape from, there has been no weeding out 
of slow flyers, and as there has been nothing to hide from, 
there has been no extermination of the bright-coloured varieties, 
and no preservation of such as tended to assimilate with sur- 
rounding objects. 

Now let us consider how this kind of protection must act. 
Tropical insectivorous birds very frequently sit on dead 
branches of a lofty tree, or on those which overhang forest 
paths, gazing intently around, and darting off at intervals to 
seize an insect at a considerable distance, which they generally 



58 NATURAL SELECTION in 

return to their station to devour. If a bird began by capturing 
the slow-flying conspicuous Heliconidse, and found them always 
so disagreeable that it could not eat them, it would after a 
very few trials leave oif catching them at all ; and their whole 
appearance, form, colouring, and mode of flight are so peculiar 
that there can be little doubt birds would soon learn to dis- 
tinguish them at a long distance, and never waste any time in 
pursuit of them. Under these circumstances, it is evident 
that any other butterfly of a group which birds were accus- 
tomed to devour would be almost equally well protected by 
closely resembling a Heliconian externally, as if it acquired 
also the disagreeable odour ; always supposing that there 
were only a few of them among a great number of the Heli- 
conias. If the birds could not distinguish the two kinds 
externally, and there were on the average only one eatable 
among fifty uneatable, they would soon give up seeking for 
the eatable ones, even if they knew them to exist. If, on the 
other hand, any particular butterfly of an eatable group 
acquired the disagreeable taste of the HeUconias while it 
retained the characteristic form and colouring of its own 
group, this would be really of no use to it whatever ; for the 
birds would go on catching it among its eatable allies (com- 
pared with which it would rarely occur), it would be wounded 
and disabled, even if rejected, and its increase would thus be 
as efiectually checked as if it were devoured. It is important, 
therefore, to understand that if any one genus of an extensive 
family of eatable butterflies were in danger of extermination 
from insect-eating birds, and if two kinds of variation were 
going on among them, some individuals possessing a slightly 
disagreeable taste, others a slight resemblance to the Heli- 
conidae, this latter quality would be much more valuable than 
the former. The change in flavour would not at all prevent 
the variety from being captured as before, and it would 
almost certainly be thoroughly disabled before being rejected. 
The approach in colour and form to the Heliconidse, however, 
would be at the very first a positive, though perhaps a slight 
advantage ; for although at short distances this variety would 
be easily distinguished and devoured, yet at a longer distance 
it might be mistaken for one of the uneatable group, and so 
be passed by and gain another day's life, which might in 



in PROTECTIVE RESEMBLANCES AMONG ANIMALS 69 

many cases be sufficient for it to lay a quantity of eggs and 
leave a numerous progeny, many of whicli would inherit 
the peculiarity which had been the safeguard of their parent. 

Now, this hypothetical case is exactly realised in South 
America. Among the white butterflies forming the family 
Pieridae (many of which do not greatly differ in appearance 
from our own cabbage butterflies) is a genus of rather small 
size (Leptalis), some species of which are white like their 
allies, while the larger number exactly resemble the Heli- 
conidse in the form and colouring of the wings. It must 
always be remembered that these two families are as absolutely 
distinguished from each other by structural characters as are 
the carnivora and the ruminants among quadrupeds, and that 
an entomologist can always distinguish the one from the 
other by the structure of the feet, just as certainly as a 
zoologist can tell a bear from a buffalo by the skull or by a 
tooth. Yet the resemblance of a species of the one family to 
another species in the other family was often so great, that 
both Mr. Bates and myself were many times deceived at the 
time of capture, and did not discover the distinctness of the 
two insects till a closer examination detected their essential 
differences. During his residence of eleven years in the 
Amazon valley, Mr. Bates found a number of species or 
varieties of Leptalis, each of which was a more or less exact 
copy of one of the Heliconidse of the district it inhabited ; 
and the results of his observations are embodied in a paper 
published in the Linncean Transactions, in which he first ex- 
plained the phenomena of " mimicry " as the result of natural 
selection, and showed its identity in cause and purpose with 
protective resemblance to vegetable or inorganic forms. 

The imitation of the Heliconidse by the Leptalides is 
carried out to a wonderful degree in form as well as in 
colouring. The wings have become elongated to the same 
extent, and the antennae and abdomen have both become 
lengthened, to correspond with the unusual condition in 
which they exist in the former family. In coloration there 
are several types in the different genera of Heliconidae. The 
genus Mechanitis is generally of a rich semi-transparent 
brown, banded with black and yellow ; Methona is of large 
size, the wings transparent like horn, and with black trans- 



60 NATURAL SELECTION iii 

verse bands ; while the delicate Ithomias are all more or less 
transparent, with black veins and borders, and often with 
marginal and transverse bands of orange red. These different 
forms are all copied by the various species of Leptalis, every 
band and spot and tint of colour, and the various degrees of 
transparency, being exactly reproduced. As if to derive all 
the benefit possible from this protective mimicry, the habits 
have become so modified that the Leptalides generally 
frequent the very same spots as their models, and have the 
same mode of flight; and as they are always very scarce 
(Mr. Bates estimating their numbers at about one to a 
thousand of the group they resemble), there is hardly a 
possibility of their being found out by their enemies. It is 
also very remarkable that in almost every case the particular 
Ithomias and other species of Heliconidse which they resemble 
are noted as being very common species, swarming in indi- 
viduals, and found over a wide range of country. This 
indicates antiquity and permanence in the species, and is 
exactly the condition most essential both to aid in the 
development of the resemblance and to increase its utility. 

But the Leptalides are not the only insects who have 
prolonged their existence by imitating the great protected 
group of Heliconidse ; — a genus of quite another family of 
most lovely small American butterflies, the Erycinidse, and 
three genera of diurnal moths, also present species which 
often mimic the same dominant forms, so that some, as 
Ithomia ilerdina of St. Paulo, for instance, have flying with 
them a few individuals of three widely different insects, 
which are yet disguised with exactly the same form, colour, 
and markings, so as to be quite undistinguishable when upon 
the wing. Again, the HeUconidae are not the only group 
that are imitated, although they are the most frequent models. 
The black and red group of South American Papilios, and 
the handsome Erycinian genus Stalachtis, have also a few 
who copy them ; but this fact offers no difficulty, since these 
two groups are almost as dominant as the Heliconidse. They 
both fly very slowly, they are both conspicuously coloured, 
and they both abound in individuals ; so that there is every 
reason to believe that they possess a protection of a similar 
kind to the Heliconidse, and that it is therefore equally an 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 61 

advantage to other insects to be mistaken for them. There 
is also another extraordinary fact that we are not yet in a 
position clearly to comprehend: some groups of the Heli- 
conidse themselves mimic other groups. Species of Heliconia 
mimic Mechanitis, and every species of Napeogenes mimics 
some other Hehconideous butterfly.^ This would seem to 
indicate that the distasteful secretion is not produced alike 
by all members of the family, and that where it is deficient 
protective imitation comes into play. It is this, perhaps, 
that has caused such a general resemblance among the HeU- 
conidse, such a uniformity of type with great diversity of 
colouring, since any aberration causing an insect to cease to 
look like one of the family would inevitably lead to its being 
attacked, wounded, and exterminated, even although it was 
not eatable. 

In other parts of the world an exactly parallel series of 
facts have been observed. The Danaidae and the Acrseidse of 
the Old World tropics form in fact one great group with the 
Heliconidae. They have the same general form, structure, 
and habits ; they possess the same protective odour, and are 
equally abundant in individuals, although not so varied in 
colour, blue and white spots on a black ground being the 
most general pattern. The insects which mimic these are 
chiefly PapiUos and Diadema, a genus allied to our peacock 
and tortoisesheU butterflies. In tropical Africa there is a 
peculiar group of the genus Danais, characterised by dark- 
brown and bluish-white colours, arranged in bands or stripes. 
One of these, Danais niavius, is exactly imitated both by 
Papilio hippocoon and by Diadema anthedon; another, Danais 
echeria, by Papilio cenea ; and in Natal a variety of the 
Danais is found having a white spot at the tip of wings, 
accompanied by a variety of the Papilio bearing a correspond- 
ing white spot. Acraea gea is copied in its very peculiar 
style of coloration by the female of Papilio cynorta, by 
Panopsea hirce, and by the female of Elymnias phegea. Acrsea 
euryta of Calabar has a female variety of Panopea hirce from 
the same place which exactly copies it ; and Mr. Trimen, in 
his paper on " Mimetic Analogies among African Butterflies," 

1 A satisfactory explanation of tliis phenomenon has now been found. See 
Darwinism, p. 252. 



62 ITATURAL SELECTION "i 

published in the Transactions of the Linnxan Society for 1868, 
gives a list of no less than sixteen species and varieties of 
Diadema and its allies, and ten of Papilio, which in their 
colour and markings are perfect mimics of species or varieties 
of Danais or Acrsea which inhabit the same districts. 

Passing on to India, we have Danais tytia, a butterfly 
with semi-transparent bluish wings and a border of rich 
reddish brown. This remarkable style of colouring is exactly 
reproduced in Papilio agestor and in Diadema nama, and all 
three insects not unfrequently come together in collections 
made at Darjeeling. In the Philippine Islands the large and 
curious Idea leuconoe, with its semi-transparent white wings, 
veined and spotted with black, is copied by the rare Papilio 
idseoides from the same islands. 

In the Malay archipelago the very common and beautiful 
Euplaea midamus is so exactly mimicked by two rare Papilios 
(P. paradoxa and P. senigma) that I generally caught them 
under the impression that they were the more common 
species ; and the equally common and even more beautiful 
Euplsea rhadamanthus, with its pure white bands and spots 
on a ground of glossy blue and black, is reproduced in the 
Papilio caunus. Here also there are species of Diadema 
imitating the same group in two or three instances ; but we 
shall have to adduce these further on in connection with 
another branch of the subject. 

It has been already mentioned that in South America 
there is a group of Papilios which have all the characteristics 
of a protected race, and whose peculiar colours and markings 
are imitated by other butterflies not so protected. There is 
just such a group also in the East, having very similar 
colours and the same habits, and these also are mimicked by 
other species in the same genus not closely allied to them, 
and also by a few of other families. Papilio hector, a 
common Indian butterfly of a rich black colour spotted with 
crimson, is so closely copied by Papilio romulus that the 
latter insect has been thought to be its female. A close 
examination shows, however, that it is essentially different, 
and belongs to another section of the genus. Papilio 
antiphus and P. diphilus, black swallow-tailed butterflies with 
cream-coloured spots, are so well imitated by varieties of P. 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 63 

tteseus, that several writers have classed them as the same 
species. Papilio liris, found only in the island of Timor, is 
accompanied there by P. senomaus, the female of which so 
exactly resembles it that they can hardly be separated in the 
cabinet, and on the wing are quite undistinguishable. But 
one of the most curious cases is the fine yellow -spotted 
Papilio coon, which is unmistakably imitated by the female 
tailed form of Papilio memnon. These are both from 
Sumatra ] but in North India P. coon is replaced by another 
species, which has been named P. doubledajd, having red 
spots instead of yellow ; and in the same district the corre- 
sponding female tailed form of Papilio androgeus, sometimes 
considered a variety of P. memnon, is similarly red-spotted. 
Mr. Westwood has described some curious day-fiying moths 
(Epicopeia) from North India, which have the form and colour 
of Papilios of this section, and two of these are very good 
imitations of Papilio polydorus and Papilio varuna, also from 
North India. 

Almost all these cases of mimicry are from the tropics, 
where the forms of life are more abundant, and where insect 
development especially is of unchecked luxuriance ; but there 
are also one or two instances in temperate regions. In North 
America, the large and handsome red and black butterfly 
Danais Archippus is very common ; and the same country is 
inhabited by Limenitis Misippus, which closely resembles the 
Danais, while it differs entirely from every species of its own 
genus. 

The only case of probable mimicry in our own country 
is that of the common white moth (Spilosoma menthastri), 
referred to at p. 56 as being rejected by young turkeys 
among hundreds of other moths on which they greedily 
fed. Each bird in succession took hold of this moth and 
threw it down again, as if too nasty to eat. Mr. Jenner 
"Weir also found that this moth was refused by the Bullfinch, 
Chaffinch, Yellow Hammer, and Red Bunting, but eaten after 
much hesitation by the Eobin. We may therefore fairly con- 
clude that this species would be disagreeable to many other 
birds, and would thus have an immunity from attack, which 
may be the cause of its great abundance and of its conspicu- 
ous white colour. Now it is a curious thing that there is 



64 NATURAL SELECTION itl 

another moth, Diaphora mendica, which appears about the 
same time, and whose female only is white. It is about the 
same size as Spilosoma menthastri, and sufficiently resembles 
it in the dusk, and this moth is much less common. It seems 
very probable, therefore, that these species stand in the same 
relation to each other as the mimicking butterflies of various 
families do to the HeHconidse and Danaidse. It would be very 
interesting to experiment on aU white moths, to ascertain if 
those which are most common are generally rejected by birds. 
It may be anticipated that they would be so, because white 
is the most conspicuous of aU colours for nocturnal insects, 
and had they not some other protection would certainly be 
very injurious to them. 

Lepidoptera mimicking other Insects 

In the preceding cases we have found Lepidoptera imitat- 
ing other species of the same order, and such species only as 
we have good reason to believe were free from the attacks of 
many insectivorous creatures ; but there are other instances 
in which they altogether lose the external appearance of the 
order to which they belong, and take on the dress of bees or 
wasps — insects which have an undeniable protection in their 
stings. The Sesiidae and ^geriidse, two families of day-flying 
moths, are particularly remarkable in this respect, and a mere 
inspection of the names given to the various species shows 
how the resemblance has struck every one. We have api- 
formis, vespiforme, ichneumoniforme, scoHseforme, sphegi- 
forme (bee-Hke, wasp-Uke, ichneumon-Hke, etc.), and many 
others, all indicating a resemblance to stinging Hymenoptera. 
In Britain we may particularly notice Sesia bombiHformis, 
which very closely resembles the male of the large and 
common humble bee, Bombus hortorum; Sphecia craboni- 
forme, which is coloured like a hornet, and is (on the 
authority of Mr. Jenner Weir) much more like it when aUve 
than when in the cabinet, from the way in which it carries its 
wings ; and the currant clear-wing, Trochilium tipuliforme, 
which resembles a small black wasp (Odynerus sinuatus) very 
abundant in gardens at the same season. It has been so 
much the practice to look upon these resemblances as mere 
curious analogies playing no part in the economy of nature, 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 65 



that we have scarcely any observations of the habits and 
appearance when alive of the hundreds of species of these 
groups in various parts of the world, or how far they are 
accompanied by Hymenoptera, which they specifically re- 
semble. There are many species in India (like those figured 
by Professor Westwood in his Oriental Entomology) which 
have the hind legs very broad and densely hairy, so as 
exactly to imitate the brush-legged bees (Scopulipedes) which 
abound in the same country. In this case we have more 
than mere resemblance of colour, for that which is an import- 
ant functional structure in the one group is imitated in 
another whose habits render it perfectly useless. 

Mimicry among Beetles 

It may fairly be expected that if these imitations of one 
creature by another really serve as a protection to weak and 
decaying species, instances of the same kind will be found 
among other groups than the Lepidoptera; and such is the case, 
although they are seldom so prominent and so easily recognised 
as those already pointed out as occurring in that order. A few 
very interesting examples may, however, be pointed out in most 
of the other orders of insects. The Coleoptera or beetles that 
imitate other Coleoptera of distinct groups are very numerous in 
tropical countries, and they generally follow the laws already 
laid down as regulating these phenomena. The insects which 
others imitate always have a special protection, which leads 
them to be avoided as dangerous or uneatable by small 
insectivorous animals; some have a disgusting taste (analogous 
to that of the Heliconidse) ; others have such a hard and 
stony covering that they cannot be crushed or digested; 
while a third set are very active, and armed with powerful 
jaws, as well as having some disagreeable secretion. Some 
species of Eumorphidse and Hispidee, small flat or hemispher- 
ical beetles which are exceedingly abundant, and have a dis- 
agreeable secretion, are imitated by others of the very 
distinct group of Longicornes (of which our common musk- 
beetle may be taken as an example). The extraordinary 
little Cyclopeplus batesii belongs to the same sub-family of 
this group as the Onychocerus scorpio and 0. concentricus, 
which have already been adduced as imitating with such 

F 



66 NATURAL SELECTION 



wonderful accuracy the bark of the trees they habitually fre- 
quent; but it differs totally in outward appearance from 
every one of its allies, having taken upon itself the exact 
shape and colouring of a globular Oorynomalus, a little stink- 
ing beetle with clubbed antennae. It is curious to see how 
these clubbed antennae are imitated by an insect belonging to 
a group with long slender antennae. The sub-family Aniso- 
cerinse, to which Cyclopeplus belongs, is characterised by all 
its members possessing a little knob or dilatation about the 
middle of the antennae. This knob is considerably enlarged 
in C. batesii, and the terminal portion of the antennae beyond 
it is so small and slender as to be scarcely visible, and thus 
an excellent substitute is obtained for the short clubbed 
antennae of the Oorynomalus. Erythroplatis corallifer is 
another curious broad flat beetle, that no one would take for 
a Longicorn, since it almost exactly resembles Cephalodonta 
spinipes, one of the commonest of the South American 
Hispidae ; and what is still more remarkable, another Longi- 
corn of a distinct group, Streptolabis hispoides, was found 
by Mr. Bates, which resembles the same insect with equal 
minuteness, — a case exactly parallel to that among butterflies, 
where species of two or three distinct groups mimicked the 
same Heliconia. Many of the soft-winged beetles (Malaco- 
derms) are excessively abundant in individuals, and it is 
probable that they have some similar protection, more 
especially as other species often strikingly resemble them. A 
Longicorn beetle, Paeciloderma terminale, found in Jamaica, is 
coloured exactly in the same way as a Lycus (one of the 
Malacoderms) from the same island. Eroschema poweri, a 
Longicorn from Australia, might certainly be taken for one of 
the same group, and several species from the Malay Islands 
are equally deceptive. In the Island of Celebes I found one 
of this group, having the whole body and elytra of a rich 
deep blue colour, with the head only orange ; and in company 
with it an insect of a totally difierent family (Eucnemidae) 
with identically the same coloration, and of so nearly the 
same size and form as to completely puzzle the collector on 
every fresh occasion of capturing them. I have been recently 
informed by Mr. Jenner Weir, who keeps a variety of small 
birds, that none of them will touch our common "soldiers 



m PROTECTIVE RESEMBLANCES AMONG ANIMALS 67 

and sailors" (species of Malacoderms), thus confirming my 
belief that they were a protected group, founded on the fact 
of their being at once very abundant, of conspicuous colours, 
and the objects of mimicry. 

There are a number of the larger tropical -weevils which 
have the elytra and the whole covering of the body so hard 
as to be a great annoyance to the entomologist, because in 
attempting to transfix them the points of his pins are con- 
stantly turned. I have found it necessary in these cases to 
drill a hole very carefully with the point of a sharp penknife 
before attempting to insert a pin. Many of the fine long- 
antennsed Anthribidse (an allied group) have to be treated in 
the same way. We can easily understand that after small 
birds have in vain attempted to eat these insects, they should 
get to know them by sight, and ever after leave them alone, 
and it will then be an advantage for other insects which are 
comparatively soft and eatable to be mistaken for them. We 
need not be surprised, therefore, to find that there are many 
Longicorns which strikingly resemble the " hard beetles " of 
their own district. In South Brazil, Acanthotritus dorsalis is 
strikingly Uke a Curculio of the hard genus Heiliplus, and 
Mr. Bates assures me that he found Gymnocerus cratoso- 
moides (a Longicorn) on the same tree with a hard Crato- 
somus (a weevil), which it exactly mimics. Again, the pretty 
Longicorn, Phacellocera batesii, mimics one of the hard 
Anthribidse of the genus Ptychoderes, having long slender 
antennse. In the Moluccas we find Cacia anthriboides, a 
small Longicorn which might be easily mistaken for a very 
common species of Anthribidse found in the same districts ; 
and the very rare Capnolymma stygium closely imitates the 
common Mecocerus gazella, which abounded where it was 
taken. DoUops curcuUonoides and other allied Longicorns 
from the Philippine Islands most curiously resemble, both in 
form and colouring, the brilliant Pachyrhynchi, — Curculi- 
onidse, which are almost peculiar to that group of islands. The 
remaining family of Coleoptera most frequently imitated is 
the CicindeHdffi. The rare and curious Longicorn, CoUyrodes 
lacordairei, has exactly the form and colouring of the genus 
Collyris, while an undescribed species of Heteromera is 
exactly like a Therates, and was taken running on the trunks 



NATURAL SELECTION 



of trees, as is the habit of that group. There is one curious 
example of a Longicorn mimicking a Longicorn, like the 
Papilios and Heliconidas which mimic their own allies. Agnia 
fasciata, belonging to the sub-family Hypselominse, and 
Nemophas grayi, belonging to the Lanuinse, were taken in 
Amboyna on the same fallen tree at the same time, and were 
supposed to be the same species till they were more carefully 
examined, and found to be structurally quite different. The 
colouring of these insects is very remarkable, being rich steel- 
blue black, crossed by broad hairy bands of orange buff, and 
out of the many thousands of known species of Longicorns 
they are probably the only two which are so coloured. The 
Nemophas grayi is the larger, stronger, and better armed 
insect, and belongs to a more widely spread and dominant 
group, very rich in species and individuals, and is therefore 
most probably the subject of mimicry by the other species. 

Beetles mimicking other Insects 

We will now adduce a few cases in which beetles imitate 
other insects, and insects of other orders imitate beetles. 

Charis melipona, a South American Longicorn of the 
family Necydalidee, has been so named from its resemblance 
to a small bee of the genus Melipona. It is one of the most 
remarkable cases of mimicry, since the beetle has the thorax 
and body densely hairy like the bee, and the legs are tufted 
in a manner most unusual in the order Coleoptera. Another 
Longicorn, Odontocera odyneroides, has the abdomen banded 
with yellow, and constricted at the base, and is altogether so 
exactly like a small common wasp of the genus Odynerus, 
that Mr. Bates informs us he was afraid to take it out 
of his net with his fingers for fear of being stung. Had 
Mr. Bates' taste for insects been less omnivorous than it 
was, the beetle's disguise might have saved it from his pin, as 
it had no doubt often done from the beak of hungry birds. 
A larger insect, Sphecomorpha chalybea, is exactly like one 
of the large metallic blue wasps, and like them has the 
abdomen connected with the thorax by a pedicel, rendering 
the deception most complete and striking. Many Eastern 
species of Longicorns of the genus Oberea, when on the wing, 
exactly resemble Tenthredinidse, and many of the small 



Ill Protective resemblances among animals 69 

species of Hesthesis run about on timber, and cannot be dis- 
tinguislied from ants. There is one genus of South American 
Longicorns that appears to mimic the shielded bugs of the 
genus Scutellera. The Gymnocerus capucinus is one of 
these, and is very like Pachyotris fabricii, one of the 
Scutelleridse. The beautiful Gymnocerus dulcissimus is also 
very like the same group of insects, though there is no 
known species that exactly corresponds to it ; but this is not 
to be wondered at, as the tropical Hemiptera have been com- 
paratively so little cared for by collectors. 

Insects mimicking Species of other Orders 

The most remarkable case of ap insect of another order 
mimicking a beetle is that of the Condylodera tricondyloides, 
one of the cricket family from the Philippine Islands, which 
is so exactly like a Tricondyla (one of the tiger beetles) that 
such an experienced entomologist as Professor Westwood 
placed it among them in his cabinet, and retained it there 
a long time before he discovered his mistake ! Both insects 
run along the trunks of trees, and whereas Tricondylas are 
very plentiful, the insect that mimics it is, as in all other 
cases, very rare. Mr. Bates also informs us that he found at 
Santarem, on the Amazon, a species of locust which mimicked 
one of the tiger beetles of the genus OdontocheUa, and was 
found on the same trees which they frequented. 

There are a considerable number of Diptera, or two-winged 
flies, that closely resemble wasps and bees, and no doubt 
derive much benefit from the wholesome dread which those 
insects excite. The Midas dives, and other species of large 
Brazilian flies, have dark wings and metallic blue elongate 
bodies, resembling the large stinging Sphegidse of the same 
country ; and a very large fly of the genus Asilus has black- 
banded wings and the abdomen tipped with rich orange, so as 
exactly to resemble the fine bee Euglossa dimidiata, and both 
are found in the same parts of South America. We have 
also in our own country species of Bombylius which are 
almost exactly like bees. In these cases the end gained by 
the mimicry is no doubt freedom from attack, but it has some- 
times an altogether different purpose. There are a number of 
parasitic flies whose larvse feed upon the larvae of bees, such 



70 NATURAL SELECTION m 

as the British genus Volucella and many of the tropical 
Bombylii, and most of these are exactly Hke the particular 
species of bee they prey upon, so that they can enter their 
nests unsuspected to deposit their eggs. There are also bees 
that mimic bees. The cuckoo bees of the genus Nomada are 
parasitic on the Andrenidse, and they resemble either wasps 
or species of Andrena ; and the parasitic humble bees of the 
genus Apathus almost exactly resemble the species of humble 
bees in ■whose nests they are reared. Mr. Bates informs us 
that he found numbers of these " cuckoo " bees and flies on 
the Amazon, which all wore the livery of working bees 
peculiar to the same country. 

There is a genus of small spiders in the tropics which feed 
on ants, and they are exactly like ants themselves, which no 
doubt gives them more opportunity of seizing their prey ; and 
Mr. Bates found on the Amazon a species of Mantis which 
exactly resembled the white ants which it fed upon, as well 
as several species of crickets (Scaphura), which resembled in 
a wonderful manner different sand-wasps of large size, which 
are constantly on the search for crickets with which to 
provision their nests. 

Perhaps the most wonderful case of all is the large cater- 
pillar mentioned by Mr. Bates, which startled him by its 
close resemblance to a small snake. The first three segments 
behind the head were dilatable at the wiU of the insect, and 
had on each side a large black pupillated spot, which re- 
sembled the eye of the reptile. Moreover, it resembled a 
poisonous viper, not a harmless species of snake, as was 
proved by the imitation of keeled scales on the crown produced 
by the recumbent feet, as the caterpillar threw itself backward ! 

The attitudes of many of the tropical spiders are most 
extraordinary and deceptive, but little attention has been 
paid to them. They often- mimic other insects, and some, 
Mr. Bates assures us, are exactly like flower buds, and take 
their station in the axils of leaves, where they remain motion- 
less waiting for their prey. 

Cases of Mimicry among the Fertehrafa 

Having thus shown how varied and extraordinary are the 
modes in which mimicry occurs among insects, we have now 



nt PROTECTIVE RESEMBLANCES AMONG ANIMALS 71 

to inquire if anything of tte same kind is to be observed 
among vertebrated animals. When we consider all the 
conditions necessary to produce a good deceptive imitation, 
we shall see at once that such can very rarely occur in the 
higher animals, since they possess none of those facilities for 
the almost infinite modifications of external form which exist 
in the very nature of insect organisation. The outer covering 
of insects being more or less solid and horny, they are capable 
of almost any amount of change of form and appearance with- 
out any essential modification internally. In many groups 
the wings give much of the character, and these organs may 
be much modified both in form and colour without interfering 
with their special functions. Again, the number of species of 
insects is so great, and there is such diversity of form and 
proportion in every group, that the chances of an accidental 
approximation in size, form, and colour of one insect to 
another of a different group are very considerable ; and it is 
these chance approximations that furnish the basis of mimicry, 
to be continually advanced and perfected by the survival of 
those varieties only which tend in the right direction. 

In the Vertebrata, on the contrary, the skeleton being 
internal, the external form depends almost entirely on the 
proportions and arrangement of that skeleton, which again is 
strictly adapted to the functions necessary for the well-being 
of the animal. The form cannot, therefore, be rapidly modified 
by variation, and the thin and flexible integument wiU not 
admit of the development of such strange protuberances as 
occur continually in insects. The number of species of each 
group in the same country is also comparatively smaU, and 
thus the chances of that first accidental resemblance which 
is necessary for natural selection to work upon are much 
diminished. We can hardly see the possibility of a mimicry 
by which the elk could escape from the wolf, or the bufialo 
from the tiger. There is, however, in one group of Verte- 
brata such a general similarity of form, that a very slight 
modification, if accompanied by identity of colour, would 
produce the necessary amount of resemblance ; and at the 
same time there exist a number of species which it would be 
advantageous for others to resemble, since they are armed 
with the most fatal weapons of offence. We accordingly find 



72 NATURAL SELECTION ni 

that reptiles furnish us with a very remarkable and instructive 
case of true mimicry. 

Mimicry among Snakes 

There are in tropical America a number of venomous 
snakes of the genus Elaps, which are ornamented with brilliant 
colours disposed in a peculiar manner. The ground colour is 
generally bright red, on which are black bands of various 
widths and sometimes divided into two or three by yeUow 
rings. Now, in the same country are found several genera of 
harmless snakes, having no affinity whatever with the above, 
but coloured exactly the same. For example, the poisonous 
Elaps fulvius often occurs in Guatemala with simple black 
bands on a coral-red ground; and in the same country is 
found the harmless snake Pliocerus equalis, coloured and 
banded in identically the same manner. A variety of Elaps 
corallinus has the black bands narrowly bordered with yellow 
on the same red ground colour, and a harmless snake, Homa- 
locranium semi-cinctum (Colubridse), has exactly the same 
markings, and both are found in Mexico. The deadly Elaps 
lemniscatus has the black bands very broad, and each of them 
divided into three by narrow yellow rings ; and this again is 
exactly copied by a harmless snake, Pliocerus elapoides, which 
is found along with its model in Mexico. 

But, more remarkable still, there is in South America a 
third group of snakes, the genus Oxyrhopus (Scytalidse), 
doubtfully venomous, and having no immediate affinity with 
either of the preceding, which has also the same curious 
distribution of colours, namely, variously disposed rings of 
red, yellow, and black; and there are some cases in which 
species of all three of these groups similarly marked inhabit 
the same district. For example, Elaps mipartitus has single 
black rings very close together. It inhabits the west side of 
the Andes, and in the same districts occur Pliocerus eury- 
zonus and Oxyrhopus petolarius, which exactly copy its 
pattern. In Brazil Elaps lemniscatus is copied by Oxyrhopus 
trigeminus, both having black rings disposed in threes. In 
Elaps hemiprichii the ground colour appears to be black, with 
alternations of two narrow yellow bands and a broader red 
one ; and of this pattern again we have an exact double in 



in PHOTECTIVE RESEMBLANCES AMOKG ANIMALS 73 

Oxyrhopus formosus, both being found in many localities of 
tropical South America. 

What adds much to the extraordinary character of these 
resemblances is the fact, that nowhere in the -world but in 
America are there any snakes which have this style of 
colouring. Dr. Gunther, of the British Museum, who has 
kindly furnished some of the details here referred to, assures 
me that this is the case ; and that red, black, and yellow rings 
occur together on no other snakes in the world but on Elaps 
and the species which so closely resemble it. In aU these 
cases, the size and form as well as the coloration are so 
much alike, that none but a naturalist would distinguish the 
harmless from the poisonous species. 

Many of the small tree-frogs are no doubt also mimickers. 
When seen in their natural attitudes, I have been often unable 
to distinguish them from beetles or other insects sitting upon 
leaves, but regret to say I neglected to observe what species 
or groups they most resembled, and the subject does not yet 
seem to have attracted the attention of naturalists abroad. 

Mimicry cmwng Birds 

In the class of birds there are a number of cases that make 
some approach to mimicry, such as the resemblance of the 
cuckoos, a weak and defenceless group of birds, to hawks and 
Gallinacese. There is, however, one example which goes much 
further than this, and seems to be of exactly the same nature 
as the many cases of insect mimicry which have been already 
given. In Australia and the Moluccas there is a genus of 
honeysuckers called Tropidorhynchus, good sized birds, very 
strong and active, having powerful grasping claws and long, 
curved, sharp beaks. They assemble together in groups and 
small flocks, and they have a very loud bawling note, which 
can be heard at a great distance, and serves to collect a 
number together in time of danger. They are very plentiful 
and very pugnacious, frequently driving away crows, and 
even hawks, which perch on a tree where a few of them are 
assembled. They are aU of rather dull and obscure colours. 
Now in the same countries there is a group of orioles, forming 
the sub-genus Mimeta, much weaker birds, which have lost 
the gay colouring of their allies, the golden orioles, being 



74 NATURAL SELECTION ni 

usually olive-green or brown ; and in several cases these most 
curiously resemble the Tropidorhynchus of the same island. 
For example, in the island of Bouru is found the Tropido- 
rhynchus bouruensis, of a dull earthy colour, and the Mimeta 
bouruensis, which resembles it in the following particulars : 
The upper and under surfaces of the two birds are exactly of 
the same tints of dark and light brown ; the Tropidorhynchus 
has a large, bare black patch round the eyes ; this is copied 
in the Mimeta by a patch of black feathers. The top of 
the head of the Tropidorhynchus has a scaly appearance, from 
the narrow scale-formed feathers, which are imitated by the 
broader feathers of the Mimeta having a dusky line down 
each. The Tropidorhynchus has a pale ruff formed of curious 
recurved feathers on the nape (which has given the whole genus 
the name of Friar birds) ; this is represented in the Mimeta 
by a pale band in the same position. Lastly, the bill of the 
Tropidorhynchus is raised into a protuberant keel at the base, 
and the Mimeta has the same character, although it is not a 
common one in the genus. The result is, that on a super- 
ficial examination the birds are identical, although they have 
important structural differences, and cannot be placed near 
each other in any natural arrangement. As a proof that the 
resemblance is really deceptive, it may be mentioned that the 
Mimeta is figured and described as a honeysucker in the costly 
Voyage de V Astrolabe, under the name of Philedon bouruensis ! 
Passing to the island of Ceram, we find allied species of 
both genera. The Tropidorhynchus subcornutus is of an earthy 
brown colour washed with yellow ochre, with bare orbits, 
dusky cheeks, and the usual pale recurved nape-ruff. The 
Mimeta forsteni is absolutely identical in the tints of every 
part of the body, the details of which are imitated in the 
same manner as in the Bouru birds already described. In 
two other islands there is an approximation towards mimicry, 
although it is not so perfect as in the two preceding cases. 
In Timor the Tropidorhynchus timoriensis is of the usual 
earthy brown above, with the nape-ruff very prominent, the 
cheeks black, the throat nearly white, and the whole under 
surface pale whitish brown. These various tints are all well 
reproduced in Mimeta virescens, the chief want of exact imita- 
tion being that the throat and breast of the Tropidorhynchus 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 75 

has a very scaly appearance, being covered with rigid pointed 
feathers which are not imitated in the Mimeta, although there 
are signs of faint dusky spots which may easily furnish the 
groundwork of a more exact imitation by the continued 
survival of favourable variations in the same direction. 
There is also a large knob at the base of the bill of the 
Tropidorhynchus which is not at all imitated by the Mimeta. 
In the island of Morty (north of Gilolo) there exists the 
Tropidorhynchus fuscicapillus, of a dark sooty brown colour, 
especially on the head, while the under parts are rather 
lighter, and the characteristic ruff of the nape is wanting. 
Now it is curious that in the adjacent island of Gilolo should 
be found the Mimeta phseochromus, the upper surface of 
which is of exactly the same dark sooty tint as the Tropido- 
rhynchus, and is the only known species that is of such a dark 
colour. The under side is not quite light enough, but it is a 
good approximation. This Mimeta is a rare bird, and may 
very probably exist in Morty, though not yet found there ; 
or, on the other hand, recent changes in physical geography 
may have led to the restriction of the Tropidorhynchus to 
that island, where it is very common. 

Here, then, we have two cases of perfect mimicry and two 
others of good approximation, occurring between species of 
the same two genera of birds ; and in three of these cases the 
pairs that resemble each other are found together in the same 
island, and to which they are peculiar. In all these cases the 
Tropidorhynchus is rather larger than the Mimeta, but the 
difference is not beyond the limits of variation in species, and 
the two genera are somewhat alike in form and proportion. 
There are, no doubt, some special enemies by which many 
small birds are attacked, but which are afraid of the Tropido- 
rhynchus (probably some of the hawks), and thus it becomes 
advantageous for the weak Mimeta to resemble the strong, 
pugnacious, noisy, and very abundant Tropidorhynchus. 

My friend, Mr. Osbert Salvin, has given me another in- 
teresting case of bird mimicry. In the neighbourhood of Eio 
Janeiro is found an insect-eating hawk (Harpagus diodon), 
and in the same district a bird-eating hawk (Accipiter pileatus) 
which closely resembles it. Both are of the same ashy tint 
beneath, with the thighs and under wing- coverts reddish 



76 Natural sELECfioU "i 

brown, so that when on the wing and seen from below they 
are undistinguishable. The curious point, however, is that 
the Acoipiter has a much wider range than the Harpagus, 
and in the regions where the insect-eating species is not found 
it no longer resembles it, the under wing-coverts varying to 
white ; thus indicating that the red-brown colour is kept true 
by its being useful to the Accipiter to be mistaken for the 
insect-eating species, which birds have learnt not to be afraid of. 

Mimicry among Mammals 

Among the Mammalia the only case which may be true 
mimicry is that of the insectivorous genus Oladobates, found 
in the Malay countries, several species of which very closely 
resemble squirrels. The size is about the same, the long 
bushy tail is carried in the same way, and the colours are 
very similar. In this case the use of the resemblance must 
be to enable the Oladobates to approach the insects or small 
birds on which it feeds under the disguise of the harmless 
fruit-eating squirrel. 

Objectims. to Mr. Bcde^ Theory of Mimicry 

Having now completed our survey of the most prominent 
and remarkable cases of mimicry that have yet been noticed, 
we must say something of the objections that have been made 
to the theory of their production given by Mr. Bates, and 
which we have endeavoured to illustrate and enforce in the 
preceding pages. Three counter explanations have been pro- 
posed. Professor Westwood admits the fact of the mimicry 
and its probable use to the insect, but maintains that each 
species was created a mimic for the purpose of the protection 
thus afforded it. Mr. Andrew Murray, in his paper on the 
" Disguises of Nature," inclines to the opinion that similar 
conditions of food and of surrounding circumstances have 
acted in some unknown way to produce the resemblances ; 
and when the subject was discussed before the Entomological 
Society of London, a third objection was added — that heredity 
or the reversion to ancestral types of form and coloration 
might have produced many of the cases of mimicry. 

Against the special creation of mimicking species there are 
all the objections and difficulties in the way of special creation 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 77 

in other cases, with the addition of a few that are peculiar to 
it. The most obvious is, that we have gradations of mimicry 
and of protective resemblance — a fact which is strongly 
suggestive of a natural process having been at work. Another 
very serious objection is, that as mimicry has been shown to 
be useful only to those species and groups whixjh are rare and 
probably dying out, and would cease to have any effect should 
the proportionate abundance of the two species be reversed, 
it follows that on the special-creation theory the one species 
must have been created plentiful, the other rare ; and, not- 
withstanding the many causes that continually tend to alter 
the proportions of species, these two species must have always 
been specially maintained at their respective proportions, or 
the very purpose for which they each received their peculiar 
characteristics would have completely failed. A third diffi- 
culty is, that although it is very easy to understand how 
mimicry may be brought about by variation and the survival 
of the fittest, it seems a very strange thing for a Creator to 
protect an animal by making it imitate another, when the 
very assumption of a Creator implies his power to create it 
so as to require no such circuitous protection. These appear 
to be fatal objections to the application of the special-creation 
theory to this particular case. 

The other two supposed explanations, which may be 
shortly expressed as the theories of " similar conditions " and 
of "heredity," agree in maldng mimicry, where it exists, an 
adventitious circumstance not necessarily connected with the 
well-being of the mimicking species. But several of the most 
striking and most constant facts which have been adduced 
directly contradict both these hypotheses. The law that 
mimicry is confined to a few groups only is one of these, for 
" similar conditions " must act more or less on all groups in a 
limited region, and "heredity" must influence all groups 
related to each other in an equal degree. Again, the general 
fact that those species which mimic others are rare, while 
those which are imitated are abundant, is in no way explained 
by either of these theories, any more than is the frequent 
occurrence of some papable mode of protection in the imitated 
species. " Keversion to an ancestral type " no way explains 
why the imitator and the imitated always inhabit the very 



78 NATURAL SELECTION m 

same district, whereas allied forms of every degree of nearness 
and remoteness generally inhabit different countries, and 
often different quarters of the globe ; and neither it nor 
"similar conditions" wiQ account for the likeness between 
species of distinct groups being superficial only — a disguise, 
not a true resemblance ; for the imitation of bark, of leaves, 
of sticks, of dung; for the resemblance between species in 
different orders, and even different classes and sub-kingdoms ; 
and finally, for the graduated series of the phenomena, 
beginning with a general harmony and adaptation of tint in 
autumn and winter moths and in arctic and desert animals, 
and ending with those complete cases of detailed mimicry 
which not only deceive predacious animals, but puzzle the 
most experienced insect collectors and the most learned 
entomologists. 

Mimicry by Female Insects only 

But there is yet another series of phenomena connected 
with this subject, which considerably strengthens the view 
here adopted, while it seems quite incompatible with either 
of the other hypotheses; namely, the relation of protective 
colouring and mimicry to the sexual differences of animals. 
It will be clear to every one that if two animals, which as 
regards " external conditions " and " hereditary descent " are 
exactly alike, yet differ remarkably in coloration, one 
resembling a protected species and the other not, the resem- 
blance that exists in one only can hardly be imputed to the 
influence of external conditions or as the effect of heredity. 
And if, further, it can be proved that the one requires 
protection more than the other, and that in, several cases it is 
that one which mimics the protected species, while the one 
that least requires protection never does so, it will afford 
very strong corroborative evidence that there is a real con- 
nection between the necessity for protection and the pheno- 
menon of mimicry. Now the sexes of insects offer us a test 
of the nature here indicated, and appear to furnish one of 
the most conclusive arguments in favour of the theory that 
the phenomena termed "mimicry'' are produced by natural 
selection. 

The comparative importance of the sexes varies much in 



in PROTECTIVE RESEMBLANCES AMONG ANIMALS 79 

different classes of animals. In the higher vertebrates, where 
the number of young produced at a birth is small and the 
same individuals breed many years in succession, the preserva- 
tion of both sexes is almost equally important. In all the 
numerous cases in which the male protects the female and 
her offspring, or helps to supply them with food, his im- 
portance in the economy of nature is proportionately increased, 
though it is never perhaps quite equal to that of the female. 
In insects the case is very different ; they pair but once in 
their Kves, and the prolonged existence of the male is in most 
cases quite unnecessary for the continuance of the race. The 
female, however, must continue to exist long enough to 
deposit her eggs in a place adapted for the development and 
growth of the progeny. Hence there is a mde difference in 
the need for protection in the two sexes; and we should, 
therefore, expect to find that in some cases the special 
protection given to the female was in the male less in amount 
or altogether wanting. The facts entirely confirm this 
expectation. In the spectre insects (Phasmidse) it is often 
the females alone that so strikingly resemble leaves, while 
the males show only a rude approximation. The male 
Diadema misippus is a very handsome and conspicuous 
butterfly, without a sign of protective or imitative colouring, 
while the female is entirely unlike her partner, and is one of 
the most wonderful cases of mimicry on record, resembling 
most accurately the common Danais chrysippus, in whose 
company it is often found. So in several species of South 
American Pieris, the males are white and black, of a similar 
type of colouring to our own " cabbage " butterflies, while the 
females are rich yeUow and buff, spotted and marked so as 
exactly to resemble species of Heliconidse, with which they 
associate in the forest. In the Malay archipelago is foimd 
a Diadema which had always been considered a male insect on 
account of its glossy metallic-blue tints, while its companion 
of sober brown was looked upon as the female. I discovered, 
however, that the reverse is the case, and that the rich and 
glossy colours of the female are imitative and protective, 
since they cause her exactly to resenible the common Euploea 
midamus of the same regions, a species which has been 
already mentioned in this essay as mimicked by another 



80 NATURAL SELECTION lii 

butterfly, Papilio paradoxa. I have since named this 
interesting species Diadema anomala (see the Transactions of 
the Entomological Society, 1869, p. 285). In this case, and 
in that of Diadema misippus, there is no difference in the 
habits of the two sexes, which fly in similar localities ; so that 
the influence of " external conditions " cannot be invoked 
here as it has been in the case of the South American Pieris 
pyrrha and allies, where the white males frequent open 
sunny places, while the Heliconia-like females haunt the 
shades of the forest. 

We may impute to the same general cause (the greater 
need of protection for the female, owing to her weaker flight, 
greater exposure to attack, and supreme importance) — the 
fact of the colours of female insects being so very generally 
duller and less conspicuous than those of the other sex. And 
that it is chiefly due to this cause rather than to what Mr. 
Darwin terms " sexual selection " appears to be shown by the 
otherwise inexplicable fact, that in the groups which have a 
protection of any kind independent of concealment, sexual 
differences of colour are either quite wanting or slightly 
developed. The Heliconidae and Danaidae, protected by a 
disagreeable flavour, have the females as bright and con- 
spicuous as the males, and very rarely differing at all from 
them. The stinging Hymenoptera have the two sexes equally 
well coloured. The Carabidse, the Coccinellidse, Ohrysomelidse, 
and the Telephori have both sexes equally conspicuous, and 
seldom diff'ering in colours. The brilliant Curculios, which 
are protected by their hardness, are brilliant in both sexes. 
Lastly, the glittering Cetoniadse and Buprestidse, which seem 
to be protected by their hard and polished coats, their rapid 
motions and peculiar habits, present few sexual diff'erences 
of colour, while sexual selection has often manifested itself 
by structural differences, such as horns, spines, or other 
processes. 

Cause of the dull Colours of Female Birds 

The same law manifests itself in Birds. The female while 
sitting on her eggs requires protection by concealment to a 
much greater extent than the male ; and we accordingly find 
that in a large majority of the cases in which the male birds 



ni PROTECTIVE RESEMBLANCES AMONG ANIMALS 81 



are distinguished by unusual brilliancy of plumage, the 
females are much more obscure, and often remarkably plain- 
coloured. The exceptions are such as eminently to prove the 
rule, for in most cases we can see a very good reason for 
them. In particular, there are a few instances among wading 
and gallinaceous birds in which the female has decidedly 
more brilliant colours than the male ; but it is a most curious 
and interesting fact that in most if not aU these cases the 
males sit upon the eggs ; so that this exception to the usual 
rule almost demonstrates that it is because the process of 
incubation is at once very important and very dangerous, 
that the protection of obscure colouring is developed. The 
most striking example is that of the gray phalarope (Phala- 
ropus fulicarius). When in winter plumage, the sexes of this 
bird are aHke in coloration, but in summer the female is 
much the most conspicuous, having a black head, dark wings, 
and reddish-brown back, while the male is nearly uniform 
brown, with dusky spots. Mr. Gould in his Birds of Great 
Britain figures the two sexes in both winter and summer 
plumage, and remarks on the strange peculiarity of the usual 
colours of the two sexes being reversed, and also on the still 
more curious fact that the "male alone sits on the eggs," 
which are deposited on the bare ground. In another British 
bird, the dotterell, the female is also larger and more brightly 
coloured than the male ; and it seems to be proved that the 
males assist in incubation even if they do not perform it 
entirely, for Mr. Gould teUs us "that they have been shot 
with the breast bare of feathers, caused by sitting on the 
eggs." The small quail-like birds forming the genus Turnix 
have also generally large and bright-coloured females, and we 
are told by Mr. Jerdon in his Birds of India that " the natives 
report that during the breeding season the females desert 
their eggs and associate in flocks while the males are employed 
in hatching the- eggs." It is also an ascertained fact that the 
females are more bold and pugnacious than the males. A 
further confirmation of this view is to be found in the fact 
(not hitherto noticed) that in a large majority of the cases in 
which bright colours exist in both sexes incubation takes 
place in a dark hole or in a dome -shaped nest. Female 
kingfishers are often equally brilliant with the male, and they 

G 



82 NATURAL gELteCTIOit itt 

build in holes in banks. Bee-eaters, trogons, motmots, and 
toucans all build in holes, and in none is there any difference 
in the sexes, although they are, -without exception, showy 
birds. Parrots build in holes in trees, and in the majority of 
cases they present no marked sexual difference tending to 
concealment of the female. Woodpeckers are in the same 
category, since, though the sexes often differ in colour, the 
female is not generally less conspicuous than the male. 
Wagtails and titmice build concealed nests, and the females 
are nearly as gay as their mates. The female of the pretty 
Australian bird, Pardalotus punctatus, is very conspicuously 
spotted on the upper surface, and it builds in a hole in the 
ground. The gay -coloured hang -nests (Icterinse) and the 
equally brilliant tanagers may be well contrasted; for the 
former, concealed in their covered nests, present little or no 
sexual difference of colour — while the open-nested tanagers 
have the females dull-coloured and sometimes with almost 
protective tints. No doubt there are many individual 
exceptions to the rule here indicated, because many and 
various causes have combined to determine both the colora- 
tion and the habits of birds. These have no doubt acted and 
reacted on each other; and when conditions have changed 
one of these characters may often have become modified, 
while the other, though useless, may continue by hereditary 
descent an apparent exception to what otherwise seems a 
very general rule. The facts presented by the sexual differ- 
ences of colour in birds and their mode of nesting are on 
the whole in perfect harmony with that law of protective 
adaptation of colour and form, which appears to have checked 
to some extent the powerful action of sexual selection, and to 
have materially influenced the colouring of female birds, as it 
has undoubtedly done that of female insects. 

Use of the gaudy Colows of many Caterpillars 
Since this essay was first published a very curious diflJculty 
has been cleared up by the application of the general principle 
of protective colouring. Great numbers of caterpillars are so 
brilliantly marked and coloured as to be very conspicuous even 
at a considerable distance, and it has been noticed that such 
caterpillars seldom hide themselves. Other species, however, 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 83 

are green or brown, closely resembling the colours of the 
substances on which they feed, while others again imita;te 
sticks, and stretch themselves out motionless from a twig so 
as to look like one of its branches. Now, as caterpillars form 
so large a part of the food of birds, it was not easy to under- 
stand why any of them should have such bright colours and 
markings as to make them specially visible. Mr. Darwin 
had put the case to me as a difficulty from another point of 
view, for he had arrived at the conclusion that brilliant 
coloration in the animal kingdom is mainly due to sexual 
selection, and this could not have acted in the case of sexless 
larvae. Applying here the analogy of other insects, I reasoned 
that since some caterpillars were evidently protected by their 
imitative colouring, and others by their spiny or hairy bodies, 
the bright colours of the rest must also be in some way useful 
to them. I further thought that as some butterflies and 
moths were greedily eaten by birds, while others were dis- 
tasteful to them, and these latter were mostly of conspicuous 
colours, so probably these brilliantly coloured caterpillars were 
distasteful, and therefore never eaten by birds. Distasteful- 
ness alone would, however, be of little service to caterpillars, 
because their soft and juicy bodies are so delicate that if 
seized and afterwards rejected by a bird, they would almost 
certainly be killed. Some constant and easily perceived 
signal was therefore necessary to serve as a warning to birds 
never to touch these uneatable kinds, and a very gaudy 
and conspicuous colouring with the habit of fully exposing 
themselves to view becomes such a signal, being in strong 
contrast with the green or brown tints and retiring habits 
of the eatable kinds. The subject was brought by me 
before the Entomological Society (see Proceedings, 4th March 
1867), in order that those members having opportunities 
for making observations might do so in the following 
summer; and I also wrote a letter to the Field news- 
paper, begging that some of its readers would co-operate 
in making observations on what insects were rejected by 
birds, at the same time fully explaining the great interest 
and scientific importance of the problem. It is a curious 
example of how few of the country readers of that paper are 
at all interested in questions of simple natural history, that I 



84 NATURAL SELECTION m 

only obtained one answer from a gentleman in Cumberland, 
who gave me some interesting observations on the general 
dislike and abhorrence of all birds to the "Gooseberry 
Caterpillar," probably that of the Magpie moth (Abraxas 
grossulariata). Neither young pheasants, partridges, nor wild 
ducks could be induced to eat it, sparrows and finches never 
touched it, and all birds to whom he offered it rejected it 
with evident dread and abhorrence. It will be seen that these 
observations are confirmed by those of two members of the 
Entomological Society, to whom we are indebted for more 
detailed information. 

In March 1869 Mr. J. Jenner Weir communicated a 
valuable series of observations made during many years, but 
more especially in the two preceding summers, in his aviary, 
containing the following birds of more or less insectivorous 
habits : — Robin, Yellow - hammer, Eeed - bunting, Bullfinch, 
Chaffinch, Crossbill, Thrush, Tree-pipit, Siskin, and EedpoU. 
He found that hairy caterpillars were uniformly rejected; 
five distinct species were quite unnoticed by all his birds, and 
were allowed to crawl about the aviary for days with impunity. 
The spiny caterpillars of the TortoisesheU and Peacock but- 
terflies were equally rejected; but in both these cases Mr. 
Weir thinks it is the taste, not the hairs or spines, that 
is disagreeable, because some very young caterpillars of a 
hairy species were rejected although no hairs were developed, 
and the smooth pupse of the above:-named butterflies were 
refused as persistently as the spined larvae. In these cases, 
then, both hairs and spines would seem to be mere signs of* 
uneatableness. 

His next experiments were with those smooth gaily- 
coloured caterpillars which never conceal themselves, but on 
the contrary appear to court observation. Such are those of 
the Magpie moth (Abraxas grossulariata), whose caterpillar is 
conspicuously white and black spotted — the Diloba cseruleo- 
cephala, whose larva is pale yellow with a broad blue or 
green lateral band — the Cucullia verbasci, whose larva is 
greenish white with yellow bands and black spots, and 
Anthrocera filipendulae (the six spot Burnet moth), whose 
caterpillar is yellow with black spots. These were given to 
the birds at various times, sometimes mixed with other kinds 



in PROTECTIVE RESEMBLANCES AMONG ANIMALS 85 

of larvae which were greedily eaten, but they were in every 
case rejected apparently unnoticed, and were left to crawl 
about till they died. 

The next set of observations were on the dull-coloured 
and protected larvse, and the results of numerous experiments 
are thus summarised by Mr. Weir. " All caterpillars whose 
habits are nocturnal, which are dull- coloured, with fleshy 
bodies and smooth skins, are eaten with the greatest avidity. 
Every species of green caterpillar is also much relished. All 
Geometrae, whose larvae resemble twigs as they stand out 
from the plant on their anal prolegs, are invariably eaten." 

At the same meeting Mr. A. Gr. Butler, of the British 
Museum, communicated the results of his observations with 
lizards, frogs, and spiders, which striMngly corroborate those 
of Mr. Weir. Three green lizards (Lacerta viridis), which he 
kept for several years, were very voracious, eating all kinds 
of food, from a lemon cheesecake to a spider, and devouring 
flies, caterpillars, and humble bees; yet there were some 
caterpillars and moths which they woidd ■seize only to drop 
immediately. Among these the principal were the caterpillar 
of the Magpie moth (Abraxas grossulariata) and the perfect 
six spot Burnet moth (Anthrocera filipendulse). These would 
be first seized but invariably dropped in disgust, and after- 
wards left unmolested. Subsequently frogs were kept and 
fed with caterpillars from the garden, but two of these — that 
of the before-mentioned Magpie moth, and that of the V. 
moth (HaUa wavaria), which is green with conspicuous white 
or yellow stripes and black spots — ^were constantly rejected. 
When these species were fii'st offered, the frogs sprang at 
them eagerly and licked them into their mouths ; no sooner, 
however, had they done so than they seemed to be aware of 
the mistake that they had made, and sat with gaping mouths, 
rolling their tongues about until they had got quit of the 
nauseous morsels. 

With spiders the same thing occurred. These two cater- 
pillars were repeatedly put into the webs both of the 
geometrical and himting spiders (Epeira diadema and Lycosa 
sp.), but in the former case they were cut out and allowed to 
drop ; in the latter, after disappearing in the jaws of their 
captor down his dark silken funnel, they invariably reappeared, 



86 NATURAL SELECTION iii 

either from below or else taking long strides up the funnel 
again. Mr. Butler has observed lizards fight with and finally 
devour humble bees, and a frog sitting on a bed of stone-crop 
leap up and catch the bees which flew over his head, and 
swallow them, in utter disregard of their stings. It is 
evident, therefore, that the possession of a disagreeable taste 
or odour is a more effectual protection to certain conspicuous 
caterpillars and moths than would be even the possession of 
a sting. 

The observations of these two gentlemen supply a very 
remarkable confirmation of the hypothetical solution of the diffi- 
culty which I had given two years before. And as it is generally 
acknowledged that the best test of the truth and complete- 
ness of a theory is the power which it gives us of prevision, 
we may, I thmk, fairly claim this as a case in which the 
power of prevision has been successfully exerted, and therefore 
as furnishing a very powerful argument in favour of the 
truth of the theory of Natural Selection. 

Summary 

I have now completed a brief, and necessarily very im- 
perfect, survey of the various ways in which the external form 
and colouring of animals is adapted to be useful to them, 
either by concealing them from their enemies or from the 
creatures they prey upon. It has, I hope, been shown that 
the subject is one of much interest, both as regards a true com- 
prehension of the place each animal fiUs in the economy of 
nature, and the means by which it is enabled to maintain that 
place ; and also as teaching us how important a part is played 
by the minutest details in the structure of animals, and how 
complicated and delicate is the equilibrium of the organic 
world. 

My exposition of the subject having been necessarily 
somewhat lengthy and fuU of details, it wiU be as well to 
recapitulate its main points. 

There is a general harmony in nature between the colours 
of an animal and those of its habitation. Arctic animals are 
white, desert animals are sand -coloured; dwellers among 
leaves and grass are green; nocturnal animals are dusky. 
These colours are not universal, but are very general, and are 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 87 

seldom reversed. Going on a little further, we find birds, 
reptiles, and insects so tinted and mottled as exactly to 
match the rock, or bark, or leaf, or flower, they are accustomed 
to rest upon, — and thereby effectually concealed. Another 
step in advance, and we have insects which are formed as 
well as coloured so as exactly to resemble particular leaves, 
or sticks, or mossy twigs, or flowers ; and in these cases very 
peculiar habits and instincts come into play to aid in the 
deception and render the concealment more complete. We 
now enter upon a new phase of the phenomena, and come to 
creatures whose colours neither conceal them nor make them 
like vegetable or mineral substances ; on the contrary, they 
are conspicuous enough, but they completely resemble some 
other creature of a quite different group, while they difier 
much in outward appearance from those with which all 
essential parts of their organisation show them to be really 
closely allied. They appear like actors or masqueraders 
dressed up and painted for amusement, or like swindlers 
endeavouring to pass themselves oif for well-known and 
respectable members of society. What is the meaning of 
this strange travesty ? Does Nature descend to impostiure or 
masquerade 1 We answer, she does not. Her principles are 
too severe. There is a use in every detail of her handiwork. 
The resemblance of one animal to another is of exactly the 
same essential nature as the resemblance to a leaf, or to bark, 
or to desert sand, and answers exactly the same purpose. In 
the one case the enemy wiU not attack the leaf or the bark, 
and so the disguise is a safeguard; in the other case it is 
found that for various reasons the creature resembled is 
passed over, and not attacked by the usual enemies of its 
order, and thus the creature that resembles it has an equally 
efiectual safeguard. We are plainly shown that the disguise 
is of the same nature in the two cases, by the occurrence in the 
same group of one species resembling a vegetable substance, 
while another resembles a living animal of another group; 
and we know that the creatures resembled possess an im- 
munity from attack, by their being always very abundant, 
by their being conspicuous and not concealing themselves, 
and by their having generally no visible means of escape from 
their enemies ; while, at the same time, the particular quality 



NATURAL SELECTION 



that makes them disliked is often very clear, such as a nasty 
taste or an indigestible hardness. Further examination 
reveals the fact that, in several cases of both kinds of dis- 
guise, it is the female only that is thus disguised ; and as it 
can be shown that the female needs protection much more 
than the male, and that her preservation for a much longer 
period is absolutely necessary for the continuance of the race, 
we have an additional indication that the resemblance is in 
all cases subservient to a great purpose — the preservation of 
the species. 

In endeavouring to explain these phenomena as having 
been brought about by variation and natural selection, we 
start with the fact that white varieties frequently occur, 
and when protected from enemies show no incapacity for 
continued existence and increase. We know, further, that 
varieties of many other tints occasionally occur ; and as " the 
survival of the fittest" must inevitably weed out those 
whose colours are prejudicial and preserve those whose 
colours are a safeguard, we require no other mode of account- 
ing for the protective tints of arctic and desert animals. 
But this being granted, there is such a perfectly continuous 
and graduated series of examples of every kind of protective 
imitation, up to the most wonderful cases of what is termed 
" mimicry," that we can find no place at which to draw the 
line, and -say: So far variation and natural selection will 
account for the phenomena, but for all the rest we require a 
more potent cause. The counter theories that have been 
proposed, that of the "special creation" of each imitative 
form, that of the action of " similar conditions of existence " 
for some of the cases, and of the laws of " hereditary descent 
and the reversion to ancestral forms " for others, — have all 
been shown to be beset with difiiculties, and the two latter 
to be directly contradicted by some of the most constant and 
most remarkable of the facts to be accounted for. 

General deductions as to Colour in Nature 

The important part that "protective resemblance" has 
played in determining the colours and markings of many 
groups of animals, will enable us to understand the meaning 
of one of the most striking facts in natiu-e, the uniformity in 



Ill PROTECTIVE RESEMBLANCES AMONG ANIMALS 89 



the colours of the vegetable as compared with the wonderful 
diversity of the animal world. There appears no good reason 
why trees and shrubs should not have been adorned with as 
many varied hues and as strikingly designed patterns as birds 
and butterflies, since the gay colours of flowers show that 
there is no incapacity in vegetable tissues to exhibit them. 
But even flowers themselves present us with none of those 
wonderful designs, those complicated arrangements of stripes 
and dots and patches of colour, that harmonious blending of 
hues in lines and bands and shaded spots, which are so 
general a feature in insects. It is the opinion of Mr. Darwin 
that we owe much of the beauty of flowers to the necessity 
of attracting insects to aid in their fertilisation, and that 
much of the development of colour in the animal world is 
due to " sexual selection," colour being universally attractive, 
and thus leading to its propagation and increase ; but while 
fully admitting this, it will be evident, from the facts and 
arguments here brought forward, that very much of the 
variety both of colour and markings among animals is due to 
the supreme importance of concealment, and thus the various 
tints of minerals and vegetables have been directly repro- 
duced in the animal kingdom, and again and again modified 
as more special protection became necessary. We shall thus 
have two causes for the development of colour in the animal 
world, and shall be better enabled to understand how, by 
their combined and separate action, the immense variety we 
now behold has been produced. Both causes, however, will 
come under the general law of "Utility," the advocacy of 
which, in its broadest sense, we owe almost entirely to Mr. 
Darwin. A more accurate knowledge of the varied pheno- 
mena connected with this subject may not improbably give 
us some information both as to the senses and the mental 
faculties of the lower animals. For it is evident that if 
colours which please us also attract them, and if the various 
disguises which have been here enumerated are equally 
deceptive to them as to ourselves, then both their powers of 
vision and their faculties of perception and emotion must be 
essentially of the same nature as our own — a fact of high 
philosophical importance in the study of oxu- own nature and 
our true relations to the lower animals. 



90 NATURAL SELECTION 



Conclusion 

Although such a store of interesting facts has been already 
accumulated, the subject we have been discussing is one of 
which comparatively little is really known. The natural 
history of the tropics has never yet been studied on the spot 
with a full appreciation of " what to observe " in this matter. 
The varied ways in which the colouring and form of animals 
serve for their protection, their strange disguises as vegetable 
or mineral substances, their wonderful mimicry of other 
beings, offer an almost unworked and inexhaustible field of 
discovery for the zoologist, and will assuredly throw much 
light on the laws and conditions which have resulted in the 
wonderful variety of coloiu:, shade, and marking which con- 
stitutes one of the most pleasing characteristics of the animal 
world, but the immediate causes of which it has hitherto 
been most difficult to explain. 

If I have succeeded in showing that in this wide and 
picturesque domain of nature, results which have hitherto 
been supposed to depend either upon those incalculable com- 
binations of laws which we term chance or upon the direct 
volition of the Creator, are really due to the action of 
comparatively well-known and simple causes, I shall have 
attained my present purpose, which has been to extend the 
interest so generally felt in the more striking facts of natural 
history to a large class of curious but much neglected details ; 
and to further, in however slight a degree, our knowledge of 
the subjection of the phenomena of life to the Beign of Law. 



IV 

ON INSTINCT IN MAN AND ANIMALS 

The most perfect and most striking examples of what is 
termed instinct — those in which reason or observation appear 
to have the least influence, and which seem to imply the 
possession of faculties farthest removed from our own — are to 
be found among insects. The marvellous constructive powers 
of bees and wasps, the social economy of ants, the careful 
provision for the safety of a progeny they are never to see 
manifested by many beetles and flies, and the curious pre- 
parations for the pupa state by the larvas of butterflies and 
moths, are typical examples of this faculty, and are supposed 
to be conclusive as to the existence of some power or intelli- 
gence very different from that which we derive from our 
senses or from our reason. 

How Instinct may be best Studied 

Whatever we may define instinct to be, it is evidently some 
form of mental manifestation, and as we can only judge of mind 
by the analogy of our own mental functions and by observa- 
tion of the results of mental action in other men and in 
animals, it is incumbent on us, first, to study and endeavour 
to comprehend the minds of infants, of savage men, and of 
animals not very far removed from ourselves, before we 
pronounce positively as to the nature of the mental operations 
in creatures so radically difi'erent from us as insects. We have 
not yet even been able to ascertain what are the senses they 
possess, or what relation their powers of seeing, hearing, and 
feeling have to ours. Their sight may far exceed ours both 
in delicacy and in range, and may possibly give them know 



92 NATURAL SELECTION iv 

ledge of the internal constitution of bodies analogous to that 
which we obtain by the spectroscope j and that their visual 
organs do possess some powers which ours do not, is indicated 
by the extraordinary crystalline rods radiating from the optic 
ganglion to the facets of the compound eye, which rods vary 
in form and thickness in different parts of their length, and 
possess distinctive characters in each group of insects. This 
complex apparatus, so different from anything in the eyes of 
vertebrates, may subserve some function quite inconceivable 
by us, as well as that which we know as vision. There is 
reason to believe that insects appreciate sounds of extreme 
delicacy, and it is supposed that certain, minute organs, plenti- 
fully supplied with nerves, and situated in the subcostal vein 
of the wing in most insects, are the organs of hearing. But 
besides these, the Orthoptera (such as grasshoppers, etc.) have 
what are supposed to be ears on their fore legs, and Mr. 
Lowne believes that the little stalked balls, which are the 
sole remnants of the hind wings in flies, are also organs of 
hearing or of some analogous sense. In flies, too, the third 
joint of the antennae contains thousands of nerve-fibres, which 
terminate in small open cells, and this Mr. Lowne believes to 
be the organ of smell, or of some other, perhaps new, sense. 
It is quite evident, therefore, that insects may possess senses 
which give them a knowledge of that which we can never 
perceive, and enable them to perform acts which to us are 
incomprehensible. In the midst of this complete ignorance 
of their faculties and inner nature, is it wise for us to judge 
so boldly of their powers by a comparison with our own? 
How can we pretend to fathom the profound mystery of their 
mental nature, and decide what, and how much, they can 
perceive or remember, reason or reflect ! To leap at one 
bound from our own consciousness to that of an insect's is as 
unreasonable and absurd as if, with a pretty good knowledge 
of the multiplication table, we were to go straight to the 
study of the calculus of functions, or as if our comparative 
anatomists should pass from the study of man's bony structure 
to that of the fish, and, without any knowledge of the 
numerous intermediate forms, were to attempt to determine 
the homologies between these distant types of vertebrata. 
In such a case would not error be inevitable, and would not 



ON INSTINCT IN MAN AND ANIMALS 



continued study in the same direction only render the 
erroneous conclusions more ingrained and more irremovable. 

Definition of Instinct 

Before going further into this subject we must determine 
what we mean by the term instinct. It has been variously 
defined as — " disposition operating without the aid of instruc- 
tion or experience," " a mental power totally independent of 
organisation," or "a power enabling an animal to do that 
which, in those things man can do, results from a chain of 
reasoning, and in things which man cannot do, is not to be 
explained by any efforts of the intellectual faculties." "We 
find, too, that the word instinct is very frequently applied to 
acts which are evidently the result either of organisation or 
of habit. The colt or calf is said to walk instinctively, almost 
as soon as it is born ; but this is solely due to its organisation, 
which renders walking both possible and pleasurable to it. 
So we are said instinctively to hold out our hands to save 
ourselves from falling, but this is an acquired habit, which 
the infant does not possess. It appears to me that instinct 
should be defined as — "the performance by an animal of 
complex acts, absolutely without instruction or previously 
acquired knowledge." Thus, acts are said to be performed 
by birds in building their nests, by bees in constructing their 
cells, and by many insects in providing for the future wants 
of themselves or their progeny, without ever having seen such 
acts performed by others, and without any knowledge of why 
they perform them themselves. This is expressed by the 
very common term "blind instinct." But we have here a 
number of assertions of matters of fact, which, strange to say, 
have never been proved to be facts at all. They are thought 
to be so self-evident that they may be taken for granted. 
No one has ever yet obtained the eggs of some bird which 
builds an elaborate nest, hatched these eggs by steam or 
under a quite distinct parent, placed them afterwards in an 
extensive aviary or covered garden, where the situation and 
the materials of a nest similar to that of the parent birds may 
be found, and then seen what kind of nest these birds would 
build. If under these rigorous conditions they choose the 
same materials, the same situation, and construct the nest in 



94 ISTATlTKAL SELECTION iv 

the same way and as perfectly as their parents did, instinct 
would he proved in their case ; now it is only assumed, and 
assumed, as I shall show further on, without any sufficient 
reason. So, no one has ever carefully taken the pupae of a 
hive of bees out of the comb, removed them from the presence 
of other bees, and loosed them in a large conservatory with 
plenty of flowers and food, and observed what kind of cells 
they would construct. But tiQ this is done, no one can say 
that bees build without instruction, no one can say that with 
every new swarm there are no bees older than those of the 
last brood, who may be the teachers in forming the new 
comb. Now, in a scientific inquiry, a point which can be 
proved should not be assumed, and a totally unknown power 
should not be brought in to explain facts, when known 
powers may be sufficient. For both these reasons I decline to 
accept the theory of instinct in any case where aU other 
possible modes of explanation have not been exhausted. 

Does Man possess Instincts 

Many of the upholders of the instinctive theory maintain 
that man has instincts exactly of the same native as those of 
animals, but more or less liable to be obscured by his reason- 
ing powers ; and as this is a case more open to our observation 
than any other, I will devote a few pages to its consideration. 
Infants are said to suck by instinct, and afterwards to walk 
by the same power, while in adult man the most prominent 
case of instinct is supposed to be the powers possessed by 
savage races to find their way across a trackless and previously 
unknown wilderness. Let us take first the case of the infant's 
sucking. It is sometimes absurdly stated that the new-born 
infant " seeks the breast," and this is held to be a wonderful 
proof of instinct. No doubt it would be if true, but unfortu- 
nately for the theory it is totally false, as every nurse and 
medical man can testify. Still, the child undoubtedly sucks 
without teaching, but this is one of those simple acts depend- 
ent upon organisation, which cannot properly be termed 
instinct, any more than breathing or muscular motion. Any 
object of suitable size in the mouth of an infant excites the 
nerves and muscles so as to produce the act of suction, and 
when, at a little later period, the will comes into play, the 



iV OiT INSTINCT lisr MAN AND ANIMALS 95 

pleasurable sensations consequent on the act lead to its con- 
tinuance. So walking is evidently dependent on the arrange- 
ment of the bones and joints, and the pleasurable exertion of 
the muscles, which lead to the vertical posture becoming 
gradually the most agreeable one ; and there can be little 
doubt that an infant would learn of itself to walk, even if 
suckled by a wild beast. 

Row Indians travel through unknown and trackless Forests 

Let us now consider the fact of Indians finding their way 
through forests they have never traversed before. This is 
much misunderstood, for I believe it is only performed under 
such special conditions as at once to show that instinct has 
nothing to do with it. A savage, it is true, can find his way 
through his native forests in a direction in which he has never 
traversed them before ; but this is because from infancy he 
has been used to wander in them, and to find his way by 
indications which he has observed himself or learnt from 
others. Savages make long journeys in many directions, and, 
their whole faculties being directed to the subject, they gain 
a wide and accurate knowledge of the topography, not only of 
their own district, but of all the regions round about. Every 
one who has travelled in a new direction communicates his 
knowledge to those who have travelled less, and descriptions 
of routes and localities, and minute incidents of travel, form 
one of the main staples of conversation roUnd the evening fire. 
Every wanderer or captive from another tribe adds to the 
store of information, and as the very existence of individuals 
and of whole families and tribes depends upon the complete- 
ness of this knowledge, all the acute perceptive faculties of 
the adult savage are devoted to acquiring and perfecting it. 
The good hunter or warrior thus comes to know the bearing 
of every hill and mountain range, the directions and junctions 
of all the streams, the situation of each tract characterised by 
peculiar vegetation, not only within the area he has himself 
traversed, but for perhaps a hundred miles around it. His 
acute observation enables him to detect the slightest undula- 
tions of the surface, the various changes of subsoil and altera- 
tions in the character of the vegetation, that would be 
imperceptible or meaningless to a stranger. His eye is always 



96 NATURAL SELECTION iv 

open to the direction in which he is going ; the mossy side 
of trees, the presence of certain plants under the shade of 
rocks, the morning and evening flight of birds, are to him 
indications of direction almost as sure as the sun in the 
heavens. Now, if such a savage is required to find his way 
across this country in a direction in which he has never been 
before, he is quite equal to the task. By however circuitous 
a route he has come to the point he is to start from, he has 
observed all the bearings and distances so well, that he knows 
pretty nearly where he is, the direction of his own home and 
that of the place he is required to go to. He starts towards 
it, and knows that by a certain time he must cross an upland 
or a river, that the streams should flow in a certain direction, 
and that he should cross some of them at a certain distance 
from their sources. The nature of the soil throughout the 
whole region is known to him, as well as all the great features 
of the vegetation. As he approaches any tract of country he 
has been in or near before, many minute indications guide 
him, but he observes them so cautiously that his white 
companions cannot perceive by what he has directed his course. 
Every now and then he slightly changes his direction, but he 
is never confused, never loses himself, for he always feels at 
home; till at last he arrives at a well-known country, and 
directs his course so as to reach the exact spot desired. To 
the Europeans whom he guides he seems to have come with- 
out trouble, without any special observation, and in a nearly 
straight unchanging course. They are astonished, and ask if 
he has ever been the same route before, and when he answers 
"No," conclude that some unerring instinct could alone 
have guided him. But take this same man into another 
country very similar to his own, but with other streams and 
hiUs, another kind of soil, with a somewhat difiierent vegeta- 
tion and animal life ; and after bringing him by a circuitous 
route to a given point, ask him to return to his starting-place, 
by a straight line of fifty miles through the forest, and he will 
certainly decline to attempt it, or, attempting it, wiU more or 
less completely fail. His supposed instinct does not act out 
of his own country. 

A savage, even in a new country, has, however, undoubted 
advantages from his familiarity with forest life, his entire 



IV ON INSTINCT IN MAN AND ANIMALS 97 

fearlessness of being lost, Ms accurate perception of direction 
and of distance, and he is thus able very soon to acquire a 
knovirledge of the district that seems marvellous to a civilised 
man ; but my own observation of savages in forest countries 
has convinced me that they find their way by the use of no 
other faculties than those which we ourselves possess. It 
appears to me, therefore, that to call in the aid of a new and 
mysterious power to account for savages being able to do that 
which, under similar conditions, we could almost all of us 
perform, although perhaps less perfectly, is almost ludicrously 
unnecessary. 

In the next essay I shall attempt to show that much of 
what has been attributed to instinct in birds can be also 
very well explained by crediting them with those faculties of 
observation, memory, and imitation, and with that limited 
amount of reason, which they undoubtedly exhibit. 



T 

THE PHILOSOPHY OF BIRDS' NESTS ^ 

Instinct or Reason in the Gonstmction of Birds' Nests 

Birds, we are told, build their nests by instinct, while man 
constructs his dwelling by the exercise of reason. Birds 
never change, but continue to build for ever on the self-same 
plan; man alters and improves his houses continually. 
Reason advances ; instinct is stationary. 

This doctrine is so very general that it may almost be 
said to be universally adopted. Men who agree on nothing 
else accept this as a good explanation of the facts. Philo- 
sophers and poets, metaphysicians and divines, naturalists 
and the general public, not only agree in believing this to be 
probable, but even adopt it as a sort of axiom that is so self- 
evident as to need no proof, and use it as the very foundation 
of their speculations on instinct and reason. A belief so 
general, one would think, must rest on indisputable facts, 
and be a logical deduction from them. Yet I have come to ' 
the conclusion that not only is it very doubtful, but absolutely 
erroneous ; that it not only deviates widely from the truth, 
but is in almost every particular exactly opposed to it. I 
believe, in short, that birds do not build their nests by 
instinct ; that man does not construct his dwelling by reason ; 
that birds do change and improve when affected by the same 
causes that make men do so ; and that mankind neither alter 
nor improve when they exist under conditions similar to 
those which are almost universal among birds. 

' First published in tlie Intellectual Observer, July 1867 ; reprinted in 
Contributions, etc., with considerahle alterations and additions ; and with 
further additions in the present volume. 



THE PHILOSOPHY OF BIRDS' NESTS 99 



Do Men huild by Beason or by Imitation ? 

Let us first consider the theory of reason, as alone deter- 
mining the domestic architectxire of the human race. Man, 
as a reasonable animal, it is said, continually alters and 
improves his dwelling. This I entirely deny. As a rule, he 
neither alters nor improves, any more than the birds do. What 
have the houses of most savage tribes improved from, each as 
invariable as the nest of a species of bird t The tents of the 
Arab are the same now as they were two or three thousand 
years ago, and the mud villages of Egypt can scarcely have 
improved since the time of the Pharaohs. The palm-leaf huts 
and hovels of the various tribes of South America and the 
Malay Archipelago, what have they improved from since 
those regions were first inhabited? The Patagonian's rude 
shelter of leaves, the hollowed bank of the South African 
Earthmen, we cannot even conceive to have been ever 
inferior to what they now are. Even nearer home, the Irish 
tiirf cabin and the Highland stone shelty can hardly have 
advanced much during the last two thousand years. Now, 
no one imputes this stationary condition of domestic archi- 
tecture among these savage tribes to instinct, but to simple 
imitation from one generation to another, and the absence of 
any sufficiently powerful stimulus to change or improvement. 
No one imagines that if an infant Arab could be transferred 
to Patagonia or to the Highlands, it would, when it grew up, 
astonish its foster-parents by constructing a tent of skins. On 
the other hand, it is quite clear that physical conditions, 
combined with the degree of civilisation arrived at, almost 
necessitate certain types of structure. The turf, or stones, 
or snow — the palm-leaves, bamboo, or branched — which are 
the materials of houses in various countries, are used because 
nothing else is so readily to be obtained. The Egyptian 
peasant has none of these, not even wood. What, then, can 
he use but mud ? In tropical forest-countries, the bamboo 
and the broad palm -leaves are the natural material for houses, 
and the form and mode of structure will be decided in part 
by the nature of the country, whether hot or cool, whether 
swampy or dry, whether rocky or plain, whether frequented 
by wild beasts, or whether subject to the attacks of enemies. 



100 NATURAL SELECTION v 

When once a particular mode of building has been adopted, 
and has become confirmed by habit and by hereditary custom, 
it wiU be long retained, even when its utility has been lost 
through changed conditions, or through migration into a very 
different region. As a general rule, throughout the whole 
continent of America, native houses, when permanent, are 
built directly upon the ground — strength and security being 
given by thickening the low walls and the roof. In almost 
the whole of the Malay Islands, on the contrary, the houses 
are raised on posts, often to a great height, with an open 
bamboo floor ; and the whole structure is exceedingly slight 
and thin. Now, what can be the reason of this remarkable 
difference between countries, many parts of which are 
strikingly similar in physical conditions, natural productions, 
and the state of civilisation of their inhabitants ? We appear 
to have some clue to it in the supposed origin and migrations 
of their respective populations. The indigenes of tropical 
America are believed to have immigrated from the north — 
from a country where the winters are severe, and raised 
houses with open floors would be hardly habitable. They 
moved southwards by land along the mountain ranges and 
uplands, and in an altered climate continued the mode of 
construction of their forefathers, modified only by the new 
materials they met with. By minute observations of the 
Indians of the Amazon VaUey, Mr. Bates arrived at the 
conclusion that they were comparatively recent immigrants 
from a colder climate. He says : " No one could live long 
among the Indians of the Upper Amazon without being 
struck with their constitutional dislike to the heat. . . . Their 
skin is hot to the touch, and they perspire little. . . . They 
are restless and discontented in hot, dry weather, but cheerful 
on cool days, when the rain is pouring down their naked 
backs." Arid, after giving many other details, he concludes, 
" How different all this is with the Negro, the true child of 
tropical climes ! The impression gradually forced itself on 
my mind that the Red Indian lives as an immigrant or 
stranger in these hot regions, and that his constitution was 
not originally adapted, and has not since become perfectly 
adapted, to the climate." 

The Malay races, on the other hand, are no doubt very 



V THE PHILOSOPHY OF BIRDS' NESTS 101 

ancient inhabitants of the hottest regions, and are par- 
ticularly addicted to forming their first settlements at the 
mouths of rivers or creeks, or in land-locked hays and inlets. 
They are a pre-eminently maritime or semi-aquatic people, 
to whom a canoe is a necessary of life, and who will never 
travel by land if they can do so by water. In accordance 
with these tastes, they have built their houses on posts in 
the water, after the manner of the lake-dwellers of ancient 
Europe ; and this mode of construction has become so con- 
firmed, that even those tribes which have spread far into the 
interior, on dry plains and rocky mountains, continue to buUd 
in exactly the same manner, and find safety in the height to 
which they elevate their dwellings above the ground. 

Why does each Bird build a peaidiar kind of Nest ? 

These general characteristics of the abode of savage man 
wUl be found to be exactly paralleled by the nests of birds. 
Each species uses the materials it can most readily obtain, 
and buUds in situations most congenial to its habits. The 
wren, for example, frequenting hedgerows and low thickets, 
builds its nest generally of moss, a material always found 
where it lives, and among which it probably obtains much of 
its insect food ; but it varies sometimes, using hay or feathers 
when these are at hand. Rooks dig in pastures and ploughed 
fields for grubs, and in doing so must continually encounter 
roots and fibres. These are used to line its nest. What more 
natural ! The crow feeding on carrion, dead rabbits, and 
lambs, and frequenting sheep-walks and warrens, chooses fur 
and wool to Une its nest. The lark frequents cultivated 
fields, and makes its nest, on the ground, of dry grass-stems 
lined with finer grass and rootlets — materials the most easy 
to meet with, and the best adapted to its needs. The king- 
fisher makes its nest of the bones of the fish which it has 
eaten. Swallows use clay and mud from the margins of the 
ponds and rivers over which they find their insect food. The 
materials of birds' nests, like those used by savage man for 
his house, are, then, those which come first to hand ; and it 
certainly requires no more special instinct to select them in 
one case than in the other. 

But, it will be said, it is not so much the materials as the 



102 NATURAL SELECTION v 

form and structure of nests, that vary so much, and are so 
wonderfully adapted to the wants and habits of each species ; 
how are these to be accounted for except by instinct? I 
reply : They may be in a great measure explained by the 
general habits of the species, the nature of the tools they 
have to work with, and the materials they can most easily 
obtain, with the very simplest adaptations of means to an 
end, quite within the mental capacities of birds. The delicacy 
and perfection of the nest will bear a direct relation to the 
size of the bird, its structure and habits. That of the wren 
or the humming-bird is perhaps not finer or more beautiful in 
proportion than that of the blackbird, the magpie, or the 
crow. The wren, having a slender beak, long legs, and great 
activity, is able with great ease to form a weU-woven nest of 
the finest materials, and places it in thickets and hedgerows 
which it frequents in its search for food. The titmouse, 
haunting fruit-trees and walls, and searching in cracks and 
crannies for insects, is naturally led to build in holes where it 
has shelter and security; while its great activity, and the 
perfection of its tools (bill and feet) enable it readily to form 
a beautiful receptacle for its eggs and young. Pigeons 
having heavy bodies and weak feet and bills (imperfect tools 
for forming a delicate structure) build rude, flat nests of 
sticks, laid across strong branches, which will bear their 
weight and that of their bulky young. They can do no 
better. The Caprimulgidse have the most imperfect tools of 
all, feet that wiU not support them except on a flat surface 
(for they cannot truly perch) and a bill excessively broad, 
short, and weak, and almost hidden by feathers and bristles. 
They cannot build a nest of twigs or fibres, hair or moss, like 
other birds, and they therefore generally dispense with one 
altogether, laying their eggs on the bare ground, or on the 
stump or flat limb of a tree. The clumsy hooked bills, short 
necks and feet, and heavy bodies of parrots, render them 
quite incapable of building a nest like most other birds. 
They cannot climb up a branch without using both bill and 
feet ; they cannot even turn round on a perch without holding 
on with their bill. How, then, could they inlay, or weave, 
or twist the materials of a nest ? Consequently they all lay 
in holes of trees, the tops of rotten stumps, or in deserted 



V THE PHILOSOPHY OF BIRDS' NESTS 103 

ants' nests, the soft materials of which they can easily hollow 
out. 

Many terns and sandpipers lay their eggs on the bare 
sand of the sea-shore, and no doubt the Duke of Argyll is 
correct when he says that the cause of this habit is not that 
they are unable to form a nest, but that, in such situations, 
any nest would be conspicuous and lead to the discovery 
of the eggs. The choice of place is, however, evidently 
determined by the habits of the birds, who, in their daily 
search for food, are continually roaming over extensive tide- 
washed flats. Gulls vary considerably in their mode of 
nesting, but it is always in accordance with their structure 
and habits. The situation is either on a bare rock or on 
ledges of sea-cliffs, in marshes or on weedy shores. The 
materials are sea-weed, tufts of grass or rushes, or the dihris 
of the shore, heaped together with as little order and con- 
structive art as might be expected from the webbed feet and 
clumsy bill of these birds, the latter better adapted for seizing 
fish than for forming a delicate nest. The long-legged broad- 
billed flamingo, who is continually stalking over muddy flats 
in search of food, heaps up the mud into a conical stool, on 
the top of which it lays its eggs. The bird can thus sit 
upon them conveniently, and they are kept dry, out of reach 
of the tides. 

Now I believe that throughout the whole class of birds 
the same general principles will be found to hold good, 
sometimes distinctly, sometimes more obscurely apparent, 
according as the habits of the species are more marked, or 
their structure more peculiar. It is true that, among birds 
differing but little in structure or habits, we see considerable 
diversity in the mode of nesting, but we are now so well 
assured that important changes of climate and of the earth's 
surface have occurred within the period of existing species, 
that it is by no means difficult to see how such differences 
have arisen. Simple habits are known to be hereditary, and 
as the area now occupied by each species is different from 
that of every other, we may be sure that such changes would 
act differently upon each, and would often bring together 
species which had acquired their peculiar habits in distinct 
regions and under different conditions. 



104 NATURAL SELECTION v 

How do Young Birds learn to Build their first Nest ? 

But it is objected, birds do not learn to make their nest as 
man does to bmld, for all birds will make exactly the same 
nest as the rest of their species, even if they have never seen 
one, and it is instinct alone that can enable them to do this. 
No doubt this would be instinct if it were true, and I simply 
ask for proof of the fact. This point, although so important 
to the question at issue, is always assumed without proof, 
and even against proof, for what facts there are, are opposed 
to it. Birds brought up from the egg in cages do not make 
the characteristic nest of their species, even though the 
proper materials are supplied them, and often make no nest 
at all, but rudely heap together a quantity of materials ; and 
the experiment has never been fairly tried of turning out a 
pair of birds so brought up into an enclosure covered with 
netting, and watching the result of their untaught attempts at 
nest-making. With regard to the songs of birds, however, 
which is thought to be equally instinctive, the experiment 
has been tried, and it is found that young birds never have 
the song peculiar to their species if they have not heard it, 
whereas they acquire very easily the song of almost any 
other bird with which they are associated. 

Bo Birds sing by Instinct or by Imitation ? 

The Hon. Daines Barrington was of opinion that " notes 
in birds are no more innate than language is in man, and 
depend entirely on the master under which they are bred, as 
far as their organs will enable them to imitate the sounds which 
they have frequent opportunities of hearing." He has given 
an account of his experiments in the Philosophical Tramsactions 
for 1773 (vol. Ixiii.) He says ; "I have educated nestling linnets 
under the three best singing larks — the skylark, woodlark, and 
titlark, every one of which, instead of the linnet's song, 
adhered entirely to that of their respective instructors. 
When the note of the titlark linnet was thoroughly fixed, I 
hung the bird in a room with two common linnets for a 
qua,rter of a year, which were full in song; the titlark 
linnet, however, did not borrow any passage from the 
linnet's song, but adhered steadfastly to that of the titlark." 



V THE PHILOSOPHY OF BIRDS' NESTS 105 

He then goes on to say that birds taken from the nest at two 
or three weeks old have already learnt the call-note of their 
species. To prevent this the birds must be taken from the 
nest when a day or two old, and he gives an account of a 
goldfinch which he saw at Knighton in Eadnorshire, and 
which sang exactly like a wren, without any portion of the 
proper note of its species. This bird had been taken from 
the nest at two or three days old, and had been hung at a 
window opposite a small garden, where it had undoubtedly 
acquired the notes of the wren without having any oppor- 
tunity of learning even the call of the goldfinch. 

He also saw a linnet, which had been taken from the 
nest when only two or three days old, and which, not having 
any other sounds to imitate, had learnt almost to articulate, 
and could repeat the words, " Pretty Boy," and some other short 
sentences. 

Another linnet was educated by himself under a vengolina 
(a small African finch, which he says sings better than any 
foreign bird but the American mocking bird), and it imitated 
its African master so exactly that it was impossible to dis- 
tinguish the one from the other. 

Still more extraordinary was the case of a common house 
sparrow, which only chirps in a wild state, but which learnt 
the song of the linnet and goldfinch by being brought up 
near those birds. 

The Rev. W. H. Herbert made similar observations, and 
states that the young whinchat and wheatear, which have 
naturally little variety of song, are ready in confinement to 
learn from other species, and become much better songsters. 
The bullfinch, whose natural notes are weak, harsh, and 
insignificant, has nevertheless a wonderful musical faculty, 
since it can be taught to whistle complete tunes. The night- 
ingale, on the other hand, whose natural song is so beautiful, 
is exceedingly apt in confinement to learn that of other birds 
instead. Bechstein gives an account of a redstart which had 
built under the eaves of his house, which imitated the song 
of a caged chaffinch in a window underneath, while another 
in his neighbour's garden repeated some of the notes of a 
blackcap, which had a nest close by. 

These facts, and many others which might be quoted. 



106 NATURAL SELECTION v 

render it certain that the peculiar notes of birds are acquired 
by imitation, as surely as a chUd learns English, or French, 
not by instinct, but by hearing the language spoken by its 
parents. 

It is especially worthy of remark that, for young birds to 
acquire a new song correctly, they must be taken out of 
hearing of their parents very soon, for in the first three or 
four days they hare already acquired some knowledge of the 
parent notes, which they will afterwards imitate. This shows 
that very young birds can both hear and remember, and it 
would be very extraordinary if, after they could see, they 
could neither observe nor recollect, and could live for days 
and weeks in a nest and know nothing of its materials and 
the manner of its construction. During the time they are 
learning to fly and return often to the nest, they must be able 
to examine it inside and out in every detail, and as we have 
seen that their daily search for food invariably leads them 
among the materials of which it is constructed, and among 
places similar to that in which it is placed, is it so very 
wonderful that when they want one themselves they should 
make one like it ? How else, in fact, should they make it ? 
Would it not be much more remarkable if they went out of 
their way to get materials quite different from those used in 
the parent nest, if they arranged them in a way they had seen 
no example of, and formed the whole structure differently 
from that in which they themselves were reared, and which 
we may fairly presume is that which their whole organisation 
is best adapted to put together with celerity and ease ? It 
has, however, been objected that observation, imitation, or 
memory can have nothing to do with a bird's architectural 
powers, because the young birds, which in England are born 
in May or June, will proceed in the following April or May 
to build a nest as perfect and as beautiful as that in which it 
was hatched, although it could never have seen one built. 
But surely the young birds lefore they left the nest had 
ample opportunities of observing its form, its size, its position, 
the materials of which it was constructed, and the manner in 
which those materials were arranged. Memory would retain 
these observations till the following spring, when the materials 
would come in their way during their daily search for food, 



V THE PHILOSOPHY OF BIRDS' NESTS 107 

and it seems highly probable that the older birds -would begin 
building first, and that those born the preceding summer would 
follow their example, learning from them how the foundations 
of the nest are laid and the material put together.^ 

Again, we have no right to assume that young birds gene- 
rally pair together. It seems probable that in each pair there 
is most frequently only one bird born the preceding summer, 
who would be guided, to some extent, by its partner. 

My friend. Dr. Richard Spruce, the well-known traveller 
and botanist, thinks this is the case, and has kindly allowed 
me to publish the following observations, which he sent me 
after reading my book. 

How young Birds may learn to build Nests 

" Among the Indians of Peru and Ecuador, many of whose 
customs are relics of the semi-civilisation that prevailed before 
the Spanish conquest, it is usual for the young men to marry 
old women, and the young women old men. A young man, 
they say, accustomed to be tended by his mother, would fare 
ill if he had only an ignorant young girl to take care of him ; 
and the girl herself would be better off with a man of mature 
years, capable of supplying the place of a father to her. 

" Something like this custom prevails among many animals. 
A stout old buck can generally fight his way to the doe of his 
choice, and indeed of as many does as he can manage ; but a 
young buck ' of his first horns ' must either content himself 
with celibacy, or with some dame well-stricken in years. 

" Compare the nearly parallel case of the domestic cock 
and of many other birds. Then consider the consequences 
amongst birds that pair, if an old cock sorts with a young 
hen and an old hen with a young cock, as I think is certainly 
the case with blackbirds and others that are known to fight 
for the youngest and handsomest females. One of each pair 

' It has been very pertinently remarked by a friend that, if young birds 
did observe the nest they were reared in, they would consider it to be a 
natural production, like the leaves and branches and matted twigs that sur- 
rounded it, and could not possibly conclude that their parents had constructed 
the one and not the other. This may be a valid objection, and if so, we shall 
have to depend on the mode of instruction described in the succeeding para- 
graphs, but the question can only be finally decided by a careful set of 
experiments. 



108 NATURAL SELECTION v 

being already an ' old bird,' will be competent to instruct its 
younger partner (not only in the futility of ' chaff,' but) in the 
selection of a site for a nest and how to build it ; then, how 
eggs are hatched and young birds reared. 

" Such, in brief, is my idea of how a bird on its first 
espousals may be taught the Whole Duty of the married 
state." 

On this difficult point I have sought for information from 
some of our best field ornithologists, but without success, as it 
is in most cases impossible to distinguish old from young 
birds after the first year. I am informed, however, that the 
males of blackbirds, sparrows, and many other kinds fight 
furiously, and the conqueror of course has the choice of a 
mate. Dr. Spruce's view is at least as probable as the 
contrary one (that young birds, as a rule, pair together), and 
it is to some extent supported by the celebrated American 
observer, Wilson, who strongly insists on the variety in the 
nests of birds of the same species, some being so much better 
finished than others ; and he believes that the less perfect nests 
are built by the yownger, the more perfect by the older, birds. 

Nearly a century ago the Swiss naturalist, Leroy, made a 
similar observation. He maintained that there is a distinctly 
perceptible inferiority in the nests built by young birds ; and 
he further remarks that the best constructed nests are made 
by birds whose young remain a long time in them, and thus 
have more opportunity of learning how they are made. He 
says that the nests of young birds are ill made and badly 
situated, and that these defects are remedied in time, when 
their builders have been instructed by a sense of the incon- 
veniences they have endured. He maintains that nests of the 
same species of bird differ as much as human dwellings, and 
that of a hundred swallows' nests no two are exactly alike ; 
and he imputes to want of long -continued observation our 
failure to discover improvement in them.^ 

At all events, till the crucial experiment is made, and a 
pair of wild birds, raised from the egg without ever seeing a 
nest, are shown to be capable of making one exactly of the 
parental type, I do not think we are justified in calling in the 

' The Intelligence and Perfectibility of Animals from a Philosophic Point 
of View. By Charles Georges Leroy. 



THE PHILOSOPHY OF BIRDS' NESTS 109 



aid of an unknown and mysterious faculty to do that which 
is so strictly analogous to the house-building of savage man. 

The observations and experiments of the late Mr. Spalding 
may seem opposed to this view, as they undoubtedly prove 
some very remarkable instinctive actions on the part of young 
chickens hatched in an incubator. These birds appear to 
recognise the call of a hen; and one chick walked or ran 
straight towards her, leaping over or running round small 
obstacles ; and this only twenty minutes after its eyes had 
been allowed to see the light and the first time it had ever 
moved its legs. A young chicken, ten minutes after its eyes 
had been unveiled for the first time, seized and swallowed 
a fly at the first stroke.^ 

In subsequent papers Mr. Spalding showed that young 
swallows could fly well and avoid obstacles on the first 
attempt ; that young pigs a few minutes old could hear and 
run to their mother, though out of sight ; and that most young 
animals give indications of fear at the voice or presence of 
their natural enemies. 

But in aU these cases we have comparatively simple motions 
or acts induced by feelings of liking or disliking ; and we can 
see that they may be due to definite nervous and muscular 
co-ordinations which are essential to the existence of the 
species. That a chicken should feel pleasure at the sound of a 
hen's voice and pain or fear at that of a hawk, and should 
move towards the one and away from the other, is a fact of 
the same nature as the liking of an infant for milk and its 
dislike of beer with the motion of the head towards the one 
and away from the other when ofiered to it. But when, at a 
much later period, with all its senses and powers of motion 
fully developed by use and exercise, and with the results of 
the experiences of a year's eventful life, the bird proceeds to 
perform the highly complex operation of building a nest, we 
have no right to assume without direct proof that it will 
be guided throughout by instinct alone ; and we have seen 
that not only is there no evidence to support this theory, but 
that all the facts we possess are directly opposed to it. 

Since this essay was published, however, some amoimt of 

1 " On Instinct." Paper read at British Association, sect. D., 1872 ; Nature, 
vol. vi. p. 486. 



110 NATURAL SELECTION v 

experiment to illustrate the question at issue has become 
available. Mr. B. T. Lowne, F.E.C.S., had three of the small 
ring-doves (Turtur risoria) which had been hatched in the 
breeding box of an ordinary dove's cage. They were kept at 
first in a similar cage, with some hay, on which the two 
hen birds laid eggs and hatched some young. In the follow- 
ing April these birds were put into an aviary in the open air, 
in which was a large branch of a tree with numerous twigs 
and buds, and there was also a breeding box with hay and 
straw. Noticing that the older birds perched on the branch 
with small pieces of stick in their bills, Mr. Lowne supplied 
them with a quantity of twigs and small sticks, and the 
very curious and interesting result was that they built a nest 
on the branch and laid their eggs in it. But this was not 
effected without much difficulty, and only after they had 
received assistance. They first seemed to try to fix the twigs 
against the waU of the aviary or its roof, and waved them 
about above their heads tiU they dropped them. Mr. Lowne 
then fixed some perches for them lower down, and wove some 
small branches together to afibrd an additional resting-place. 
They took possession of this and again carried up twigs and 
dropped them, and Mr. Lowne then observed that while the 
straight smooth twigs fell to the ground those that were forked 
often lodged in the branches. He therefore supplied them with 
plenty of forked or branched twigs, and by carrying these up 
and dropping them (and I presume standing on them, or other- 
wise rendering them compact, though this is not mentioned) 
they at length (in three days) formed a nest " exactly like 
that of a wood-pigeon." This " they lined neatly with straw," 
and each dove laid two eggs in it.^ 

This experiment, though very interesting, is by no means 
satisfactory or conclusive. In the first place, pigeons are the 
very rudest of nest-builders, and vsdll sometimes lay their eggs 
on a dense flat bough without any nest at all. Then it is clear 
that these birds had no notion how to begin to build ; they 
required to be assisted, and, as Mr. Lowne says, " as soon as 
a few branches had lodged below them, they finished the nest 
which accident had commenced for them." Then they lined it with 
straw, which is not their habit in a state of nature, but appears 

^ Popular Science Review, New Series, vol. iii. p. .274 



V THE PHILOSOPHY OF BIKDS' NESTS 111 

to have been the result of their having been used to such a 
nest. The one thing that remains, and which Mr. Lowne 
thinks proves instinct, is their not forming their nest in the 
box they had been accustomed to, and their using sticks and 
twigs instead of straw only. But they evidently preferred 
the light and air and movement of the branch. That was all 
in harmony with their special organisation, and was a return to 
the habits which were at once the result and the cause of that 
organisation. They preferred to make the nest in this pleasant 
place, but they did not know how to begin. As soon as the 
sticks, lodged by accident, furnished a sufficient base, they car- 
ried up more sticks and soon obtained a rude nest. They saw 
that smooth straight twigs dropped to the ground, whereas 
branched twigs kept in the branches, and they had quite 
sense and observation enough to choose the branched twigs 
for the purpose. In all this there seems to me to be no proof 
of the operation of instinct as usually understood, and the 
experiment yet requires trying with some of our native birds 
that build elaborate and very distinctive nests, such as the 
song-thrush, the gold-crest, the wren or the long-tailed tit. If 
several of these could be brought up in strange nests, and 
then be turned out into a large wired enclosure containing 
shrubs and bushes, and if under these circumstances each built 
an unmistakable nest of its own species, the nest-building 
instinct would have to be admitted. 

The nearest approach to such a test experiment has been 
recently furnished by Mr. Charles Dixon. He states that 
some young chaffinches (Fringilla Coelebs) were taken to New 
Zealand and there turned out. They throve well, and a nest 
built by a pair of them was photographed, and from this photo- 
graph the nest is thus described by Mr. Dixon : " It is evidently 
built in the fork of a branch, and shows very little of that neat- 
ness of fabrication for which this bird is noted in England. The 
cup of the nest is small, loosely put together, apparently lined 
with feathers, and the walls of the structure are prolonged 
about eighteen inches and hang loosely down the side of the 
supporting branch. The whole structure bears some resem- 
blance to the nests of the hangnests, with the exception that 
the cavity containing the eggs is situated on the top. Clearly 
these New Zealand chaffinches were at a loss for a design 



112 NATURAL SELECTION v 

when fabricating their nest. They had no standard to work 
by, no nests of their own kind to copy, no older birds to give 
them any instruction, and the result is the abnormal structure 
I have just described. Perhaps these chaffinches imitated in 
some degree the nest of some New Zealand species ; or it 
may be that the few resemblances to the typical nest of the 
Palsearctic chaffinch are the results of memory — the dim 
remembrance of the nest in which they had been reared, but 
which had almost been effaced by novel surroundings and 
changed conditions of life. Any way we have here, at least, 
a most interesting and convincing proof that birds do nor 
make their nests by blind instinct, but by imitating the nest 
in which they were reared, aided largely by rudimentary 
reason and by memory." ^ 

This experiment also leaves much to be desired, but it 
undoubtedly shows that instinct alone does not determine 
the form and structure of a bird's nest, or we should not see 
so great a departure from the type in the case of the New 
Zealand chaffinches. 

The Skill exhibited in Nest-huilding Exaggerated 

We are too apt to assume that because a nest appears to 
us delicately and artfully built, it therefore requires much 
special knowledge and acquired skill (or their substitute, 
instinct) in the bird who builds it. We forget that it is 
formed twig by twig and fibre by fibre, rudely enough at first, 
but crevices and irregularities, which must seem huge gaps 
and chasms in the eyes of the little builders, are filled up by 
twigs and stalks pushed in by slender beak and active foot, 
and that the wool, feathers, or horsehair are laid thread by 
thread, so that the result seems a marvel of ingenuity to us, 
just as would the rudest Indian hut to a native of Brobdignag. 

Levaillant has given an account of the process of nest- 
building by a little African warbler, which sufficiently shows 
that a very beautiful structure may be produced with very 
little art. The foundation was laid of moss and flax inter- 
woven with grass and tufts of cotton, and presented a rude 
mass, five or six inches in diameter, and four inches thick. 
This was pressed and trampled down repeatedly, so as at last 
1 Natwre, vol. xxxi. p. 533 (April 1885). 



V THE PHILOSOPHY OF BIRDS' NESTS 113 

to make it into a kind of felt. The birds pressed it with 
their bodies, turning round upon them in every direction, so 
as to get it quite firm and smooth before raising the sides. 
These were added bit by bit, trimmed and beaten with the 
wings and feet, so as to felt the whole together, projecting 
fibres being now and then worked in with the bill. By these 
simple and apparently inefficient means, the inner surface of 
the nest was rendered almost as smooth and compact as a 
piece of cloth. 

Man's Works mainly Imitative 

But look at civilised man ! it is said ; look at Grecian, and 
Egyptian, and Roman, and G-othic, and modern architecture ! 
What advance ! what improvement ! what refinements ! This 
is what reason leads to, whereas birds remain for ever 
stationary. If, however, such advances as these are required 
to prove the effects of reason as contrasted with instinct, then 
all savage and many half-civilised tribes have no reason, but 
build instinctively quite as much as birds do. 

Man ranges over the whole earth, and exists under the 
most varied conditions, leading necessarily to equally varied 
habits. He migrates — he makes wars and conquests — one 
race mingles with another — different customs are brought 
into contact — the habits of a migrating or conquering race 
are modified by the different circumstances of a new country. 
The civilised race which conquered Egypt must have de- 
veloped its mode of building in a forest country where timber 
was abundant, for it is not probable that the idea of cylin- 
drical columns originated in a country destitute of trees. The 
pyramids might have been built by an indigenous race, but 
not the temples of Luxor and Karnak. In Grecian archi- 
tecture almost every characteristic feature can be traced to an 
origin in wooden buildings. The columns, the architrave, the 
frieze, the fillets, the cantilevers, the form of the roof, all 
point to an origin in some southern forest-clad country, and 
strikingly corroborate the view derived from philology, that 
Greece was colonised from north-western India. But to erect 
columns and span them with huge blocks of stone, or marble, 
is not an act of reason, but one of pure unreasoning imita- 
tion. The arch is the only true and reasonable mode of 
covering over wide spaces with stone, and, therefore, Grecian 

I 



114 NATURAL SELECTION \ 

architecture, however exquisitely beautiful, is false in prin- 
ciple, and is by no means a good example of the application 
of reason to the art of building. And what do most of us 
do at the present day but imitate the buildings of those that 
have gone before us 1 We have not even been able to dis- 
cover or develop any definite style of building best suited for 
us. We have no characteristic national style of architecture, 
and to that extent are even below the birds, who have each 
their characteristic form of nest, exactly adapted to their 
wants and habits. 

Birds do Alter and Improve their Nests when altered Con- 
ditions require it 

The great uniformity in the architecture of each species of 
bird which has been supposed to prove a nest-building instinct, 
may, therefore, fairly be imputed to the uniformity of the 
conditions under which each species lives. Their range is 
often limited, and they very seldom permanently change 
their country, so as to be placed in new conditions. When, 
however, new conditions do occur, they take advantage of 
them just as freely and wisely as man could do. The 
chimney and house - swallows are a standing proof of a 
change of habit since chimneys and houses were built, and 
in America this change has taken place within about three 
hundred years. Thread and worsted are now used in many 
nests instead of wool and horsehair, and the jackdaw shows 
an affection for the church steeple, which can hardly be 
explained by instinct. In the more thickly populated parts 
of the United States the Baltimore Oriole uses all sorts of 
pieces of string, skeins of silk, or the gardener's bass, to weave 
into its fine pensile nest, instead of the single hairs and vege- 
table fibres it has painfully to seek in wilder regions ; and, 
as already stated, WUson, a most careful observer, believes 
that it improves in nest-building by practice — the older birds 
making the best nests. More recently. Dr. Abbott, the well- 
known American naturalist, has studied the nests of the 
Baltimore Oriole. He found that, away from the habitations 
of man, the orioles built concealing nests ; but in villages 
and cities, on the other hand, where they were in no special 
danger from predatory hawks (or more probably from snakest 



V THE PHILOSOPHY OF BIRDS' NESTS 115 

the nests were built comparatively open, so that the bird 
within was not concealed.^ The purple martin takes posses- 
sion of empty gourds or small boxes, stuck up for its reception 
in almost every village and farm in America ; and several 
of the American wrens will also build in cigar boxes, with a 
small hole cut in them, if placed in a suitable situation. The 
orchard oriole of the United States offers us an excellent 
example of a bird which modifies its nest according to circum- 
stances. When built among firm and stiff branches the nest 
is very shallow, but if, as is often the case, it is suspended 
from the slender twigs of the weeping willow, it is made 
much deeper, so that when swayed about violently by the 
wind the young may not tumble out. It has been observed 
also that the nests built in the warm Southern States are 
much slighter and more open in texture than those in the 
colder regions of the north. Our own house-sparrow equally 
well adapts himself to circumstances. When he builds in 
trees, as- he, no doubt, always did originally, he constructs a 
well-made domed nest, perfectly fitted to protect his young 
ones ; but when he can find a convenient hole in a building or 
among thatch, or in any well-sheltered place, he takes much 
less trouble, and forms a very loosely-built nest. 

Professor Jeitteles of Vienna has described various forms of 
nests of Hirundo urbica adapted to different situations, some 
having the form of a semi-ellipsoid placed vertically, with the 
entrance at one side, others being three-quarters of a sphere, 
with the entrance in the centre. A nest of Hirundo rustica 
was also observed supported on an iron hook in a wall, but 
not itself touching the wall. It was quite hemispherical, like 
that of a blackbird, a form common in England, whereas the 
usual form on the Continent is that of a quarter of a 
sphere.^ 

The following case of a recent change of habit in nest- 
building was communicated to me by Mr. Henry Reeks in 
1870 : "Thirty years ago, and perhaps less, the herring-gulls 
used to breed on some inland rocks in a large lake called 

1 Popular Science Monthly, vol. vi. p. 481. Quoted by Vice-President 
E. S. Morse, in Address to American Association for Advancement of Science 
at Buffalo, N.Y., August 1876. 

2 Omithologischer Verein in Wien. Mitthelungen des Ausschusses, No. 3, 
12 Juli 1876. See also Seebohm's British Bi/rds, vol. ii. p. 174. 



116 NATURAL SELECTION v 

'Parsons Pond,' in Newfoundland, which is separated from 
the sea only by a high pebbly beach. Within the period 
above stated high tides and heavy seas have shifted the course 
of the brook flowing from the lake into the sea, and caused a 
greater, and consequently a more rapid fall of fresh water, 
which has so shallowed that part of the lake where the gulls 
were in the habit of breeding that it was no longer safe to 
build on rocks easily accessible to their common enemy, the 
fox. They therefore betook themselves to some neighbouring 
spruce and balsam firs not much over a hundred yards distant 
from their old breeding station." Audubon also notes a 
similar change of habit, some herring-gulls building their nests 
in spruce-trees on an island in the Bay of Fundy, where they 
had formerly built on the ground. 

A curious example of a recent change of habits has oc- 
curred in Jamaica. Previous to 1854 the palm swift 
(Tachornis phoenicobea) inhabited exclusively the palm trees 
in a few districts in the island. A colony then established 
themselves in two cocoa-nut palms in Spanish Town, and 
remained there till 1857, when one tree was blown down and 
the other stripped of its foliage. Instead of now seeking out 
other palm trees the swifts drove out the swallows who built 
in the piazza of the House of Assembly, and took possession 
of it, building their nests on the tops of the end walls and at 
the angles formed by the beams and joists, a place which they 
continue to occupy in considerable numbers. It is remarked 
that here they form their nest with much less elaboration than 
when built in the palms, probably from being less exposed. 

But perfection of structure and adaptation to purpose are 
not universal characteristics of birds' nests, since there are 
decided imperfections in the nesting of many birds which are 
quite compatible with our present theory, but are hardly so 
with that of instinct, which is supposed' to be infallible.. The 
passenger pigeon of America often crowds the branches with 
its nests till they break, and the ground is strewn with 
shattered nests, eggs, and young birds. Eooks' nests are 
often so imperfect that during high winds the eggs fall out ; 
but the window-swallow is the most unfortunate in this re- 
spect, for White, of Selborne, informs us that he has seen them 
build, year after year, in places where their nests are liable 



V THE PHILOSOPHY OF BIRDS' NESTS 117 

to be washed away by a heavy rain and their young ones 
destroyed. 

Conclusion 
A fair consideration of all these facts will, I think, fully 
support the statement with which I commenced, and show 
that the chief mental faculties exhibited by birds in the con- 
struction of their nests are the same in kind as those mani- 
fested by mankind in the formation of their dwellings. These 
are, essentially, imitation, and a slow and partial adaptation 
to new conditions. To compare the work of birds with the 
highest manifestations of human art and science is totally 
beside the question. I do not maintain that birds are gifted 
with reasoning faculties at all approaching in variety and 
extent to those of man. I simply hold that the phenomena 
presented by their mode of building their nests, when fairly 
compared with those exhibited by the great mass of mankind 
in building their houses, indicate no essential difference in the 
kind or nature of the mental faculties employed. If instinct 
means anything, it means the capacity to perform some com- 
plex act without teaching or experience. It implies, not only 
innate ideas but innate knowledge of a very definite kind, and, 
if established, would overthrow Mr. Mill's sensationalism and 
all the modern philosophy of experience. That the existence 
of true instinct may be established in other cases is not 
impossible ; but in the particular instance of birds' nests, which 
is usually considered one of its strongholds, I cannot find a 
particle of evidence to show the existence of anything beyond 
those lower reasoning and imitative powers which animals 
are universally admitted to possess. 



VI 



A THEORY OF BIRDS NESTS, SHOWING THE RELATION OF 

CERTAIN DIFFERENCES OF COLOUR IN FEMALE BIRDS 

TO THEIR MODE OF NIDIFICATION ^ 

The habit of forming a more or less elaborate structure for 
the reception of their eggs and young must undoubtedly be 
looked upon as one of the most remarkable and interesting 
characteristics of the class of birds. In other classes of verte- 
brate animals, such structures are few and exceptional, and 
never attain to the same degree of completeness and beauty. 
Birds' nests have, accordingly, attracted much attention, and 
have furnished one of the stock arguments to prove the exist- 
ence of a blind but unerring instinct in the lower animals. 
The very general belief that every bird is enabled to build its 
nest, not by the ordinary faculties of observation, memory, 
and imitation, but by means of some innate and mysterious im- 
pulse, has had the bad effect of withdrawing attention from the 
very evident relation that exists between the structure, habits, 
and intelligence of birds, and the kind of nests they construct. 

In the preceding essay I have detailed several of these 
relations, and they teach us that a consideration of the 
structure, the food, and other specialities of a bird's existence 
will give a clue, and sometimes a very complete one, to the 
reason why it builds its nest of certain materials, in a definite 
situation, and in a more or less elaborate manner. 

I now propose to consider the question from a more general 
point of view, and to discuss its application to some important 
problems in the natural history of birds. 

' Published in tlie Jowrnal of Tromel and Naiwal History, No. 2 ; 
reprinted in Contributions, etc., with considerable additions and corrections. 



VI A THEORY OF BIRDS' NESTS 119 

Ghcmged Conditions and persistent Habits as influencing 
Nidification 

Besides the causes above alluded to, there are tvro other 
factors whose effect in any particular case we can only vaguely 
guess at, but which must have had an important influence in 
determining the existing details of nidification. These are — 
changed conditions of existence, whether internal or external, 
and the influence of hereditary or imitative habit ; the first 
inducing alterations in accordance with changes of organic 
structure, of climate, or of the surrounding fauna and flora ; 
the other preserving the peculiarities so produced, even when 
changed conditions render them no longer necessary. Many 
facts have been already given which show that birds do adapt 
their nests to the situations in which they place them, and the 
adoption of eaves, chimneys, and boxes by swallows, wrens, 
and many other birds, shows that they are always ready to 
take advantage of changed conditions. It is probable, there- 
fore, that a permanent change of climate would cause many 
birds to modify the form or materials of their abodes, so as 
better to protect their young. The introduction of new 
enemies to eggs or young birds might introduce many alter- 
ations tending to their better concealment. A change in the 
vegetation of a country would often necessitate the use of 
new materials. So, also, we may be sure, that as a species 
slowly became modified in any external or internal characters, 
it would necessarily change in some degree its mode of build- 
ing. This effect would be produced by modifications of the 
most varied nature ; such as the power and rapidity of flight, 
which must often determine the distance to which a bird will 
go to obtain materials for its nest ; the capacity of sustaining 
itself almost motionless in the air, which must sometimes 
determine the position in which a nest can be built; the 
strength and grasping power of the foot in relation to the 
weight of the bird, a power absolutely essential to the con- 
structor of a delicately -woven and well-finished nest; the 
length and fineness of the beak, which has to be used like 
a needle in building the best textile nests ; the length and 
mobility of the neck, which is needful for the same purpose ; 
the possession of a salivary secretion like that used in the 



120 NATURAL SELECTION vi 

nests of many of the swifts and swallows, as well as that of 
the song-thrush— peculiarities of habits which ultimately 
depend on structure, and which often determine the material 
most frequently met with or most easily to be obtained. 
Modifications in any of these characters would necessarily 
lead either to a change in the materials of the nest, or in the 
mode of combining them in the finished structure, or in the 
form or position of that structure. 

During all these changes, however, certain specialities of 
nest-building would continue for a shorter or a longer time 
after the causes which had necessitated them had passed 
away. Such records of a vanished past meet us everywhere, 
even in man's works, notwithstanding his boasted reason. 
Not only are the main features of Greek architecture mere 
reproductions in stone of what were originally parts of a 
wooden building, but our modern copyists of Gothic archi- 
tecture often build solid buttresses capped with weighty 
pinnacles to support a wooden roof which has no outward 
thrust to render them necessary; and even think they 
ornament their buildings by adding sham spouts of carved 
stone, while modern waterpipes, stuck on without any attempt 
at harmony, do the real duty. So, when railways superseded 
coaches, it was thought necessary to build the first-class 
carriages to imitate a number of coach-bodies joined together; 
and the arm-loops for each passenger to hold on by, which 
were useful when bad roads made every journey a succession 
of jolts and lurches, were continued on our smooth macadam- 
ised mail-routes, and, still more absurdly, remain to this day ^ 
in our railway carriages, the relic of a kind of locomotion we 
can now hardly realise. Another good example is to be seen 
in our boots. When elastic sides came into fashion we had 
been so long used to fasten them with buttons or laces, that 
a boot without either looked bare and unfinished, and accord- 
ingly the makers often put on a row of useless buttons or 
imitation laces, because habit rendered the appearance of 
them necessary to us. It is universally admitted that the 
habits of children and of savages give us the best clue to the 
habits and mode of thought of animals ; and every one must 
have observed how children at first imitate the actions of 

^ Siace this was written tliey have generally been disused. 



VI A THEORY OF BIRDS' NESTS 121 

their elders, without any regard to the use or applicability of 
the particular acts. So, in savages, many customs peculiar to 
each tribe are handed down from father to son merely by the 
force of habit, and are continued long after the purpose which 
they originally served has ceased to exist. With these and a 
hundred similar facts everywhere around us, we may fairly 
impute much of what we cannot understand in the details of 
Bird-Architecture to an analogous cause. If we do not do so, 
we must assume either that birds are guided in every action 
by pure reason to a far greater extent than men are, or that 
an infallible instinct leads them to the same result by a 
different road. The first theory has never, that I am aware 
of, been maintained by any author, and I have already shown 
that the second, although constantly assumed, has never been 
proved, and that a large body of facts is entirely opposed to 
it. One of my critics has, indeed, maintained that I admit 
"instinct" under the term "hereditary habit"; but the 
whole course of my argument shows that I do not do so. 
Hereditary habit is, indeed, the same as instinct when the 
term is applied to some simple action dependent upon a 
peculiarity of structure which is hereditary; as when the 
descendants of tumbler pigeons tumble, and the descendants 
of pouter pigeons pout. In the present case, however, I 
compare it strictly to the hereditary, or more properly, per- 
sistent or imitative, habits of savages, in building their 
houses as their fathers did. Imitation is a lower faculty 
than invention. Children and savages imitate before 
they originate; birds, as well as all other animals, do the 
same. 

The preceding observations are intended to show that the 
exact mode of nidification of each species of bird is probably 
the result of a variety of causes, which have been continually 
inducing changes in accordance with changed organic or 
physical conditions. The most important of these causes 
seem to be, in the first place, the structure of the species, 
and, in the second, its environment or conditions of existence. 
Now, we know that every one of the characters or conditions 
included under these two heads is variable. We have seen 
that,- on the large scale, the main features of the nest built by 
each group of birds bears a relation to the organic structure 



122 NATURAL SELECTIOST vi 

of that group, and we have, therefore, a right to infer that as 
structure varies, the nest vnll vary also in some particular 
corresponding to the changes of structure. We have seen 
also that birds change the position, the form, and the con- 
struction of their nest whenever the available materials or 
the available situations vary natui'ally or have been altered 
by man ; and we have, therefore, a right to infer that similar 
changes have taken place when, by a natural process, external 
conditions have become in any way permanently altered. We 
must remember, however, that all these factors are very stable 
during many generations, and only change at a rate com- 
mensurate with those of the great physical features of the 
earth as revealed to us by geology ; and we may, therefore, 
infer that the form and construction of nests, wluch we have 
shown to be dependent on them, are equally stable. If, 
therefore, we find less important and more easily modified 
characters than these so correlated with pecidiarities of 
nidification as to indicate that one is probably the cause of 
the other, we shall be justified in concluding that these 
variable characters are dependent on the mode of nidification, 
and not that the form of the nest has been determined by 
these variable characters. Such a correlation I am now 
about to point out. 

Classification of Nests 

For the purpose of this inquiry it is necessary to group 
nests into two great classes, without any regard to their most 
obvious difi'erences or resemblances, but solely looking to the 
fact of whether the contents (eggs, young, or sitting bird) are 
hidden or exposed to view. In the first class we place all 
those in which the eggs and young are completely hidden, 
no matter whether this is effected by an elaborate covered 
structure, or by depositing the eggs in some hollow tree or 
burrow underground. In the second, we group all in which 
the eggs, young, and sitting bird are exposed to view, no 
matter whether there is the most beautifully formed nest or 
none at all. Kingfishers, which build almost invariably in 
holes in banks; woodpeckers and parrots, which build in 
hollow trees; the Icteridse of America, which all make 
beautiful covered and suspended nests ; and our own wren, 
which builds a domed nest — are examples of the former ; 



Vt A THEORY OF BIRDS' NESTS 123 

while our thrushes, warblers, and finches, as well as the crow- 
shrikes, chatterers, and tanagers of the tropics, together with all 
raptorial birds and pigeons, and a vast number of others in 
every part of the world, aU adopt the latter mode of building. 

It will be seen that this division of birds, according to 
their nidification, bears little relation to the character of the 
nest itself. It is a functional not a structural classification. 
The most rude and the most perfect specimens of bird- 
architecture are to be found in both sections. It has, how- 
ever, a certain relation to natural afiinities, for large groups of 
birds, undoubtedly allied, fall into one or the other division 
exclusively. The species of a genus or of a family are rarely 
divided between the two primary classes, although they are 
frequently divided between the two very distinct modes of 
nidification that exist in the first of them. 

All the Scansorial or climbing, and most of the Fissirostral 
or wide-gaped birds, for example, build concealed nests ; and 
in the latter group the two families which build open nests, 
the swifts and the goatsuckers, are undoubtedly very widely 
separated from the other families with which they are asso- 
ciated in our classifications.^ The tits vary much in their 
mode of nesting, some making open nests concealed in a hole, 
whUe others build domed or even pendulous covered nests, 
but they all come under the same class. Starlings vary in a 
similar way. The talking mynahs, like our own starlings, 
build in holes, the glossy starlings of the East (of the genus 
Calornis) form a hanging covered nest, while the genus 
Sturnopastor builds in a hollow tree. One of the most 
striking cases in which one family of birds is divided between 
the two classes is that of the finches ; for while most of the 
European species build exposed nests, many of the Australian 
finches make them dome-shaped. 

Sexual differences of Colom in Birds 
Turning now from the nests to the creatures who make 
them, let us consider birds themselves from a somewhat 
unusual point of view, and form them into separate groups, 

1 Eecent research places the goatsuckers nearest to (though still far 
from) the owls, while swifts are again brought nearer to the swallows. 
Dr. E. W. Shufeldt in Joum. of the Lmn. Soc, vol. xx. Zoology, p. 383. 



124 NATURAL SELECTION vi 

according as both sexes, or the males only, are adorned with 
conspicuous colours. 

The sexual differences of colour and plumage in birds are 
very remarkable, and have attracted much attention ; and, in 
the case of polygamous birds, have been explained by Mr. 
Darwin's principle of sexual selection. We may, perhaps, 
understand how male pheasants and grouse have acquired 
their more brilliant plumage and greater size by the continual 
rivalry of the males both in strength and beauty ; but this 
theory does not throw any light on the causes which have 
made the female toucan, bee -eater, parroquet, macaw, and 
tit in almost every case as gay and brilliant as the male, 
while the gorgeous chatterers, manakins, tanagers, and birds 
of paradise, as well as our own blackbird, have mates so duU 
and inconspicuous that they can hardly be recognised as 
belonging to the same species. 

The Law which connects the Colours of Female Birds 
with the mode of Nidification 

The above-stated anomaly can, however, now be explained 
by the influence of the mode of nidification, since, with very 
few exceptions, I find it to be the rule — that when both 
sexes are of strikingly gay and conspicuous colov/rs the nest is of the 
first class, or such as to conceal the sitting birds ; while, whenever 
the male is gay and conspicuous and the nest is open so as to expose 
the sitting bird to view, the female is of dull or obscwe colov/rs. I 
will now proceed to indicate the chief facts that support this 
statement, and will afterwards explain the manner in which I 
conceive the relation has been brought about. 

We will first consider those groups of birds in which the 
female is gaily or at least conspicuously coloured, and is in 
most cases exactly like the male. 

1. Kingfishers (Alcedinidse). In some of the most brilliant 
species of this family the female exactly resembles the male ; 
in others there is a sexual difierence, but it rarely tends to 
make the female less conspicuous. In some the female has a 
coloured band across the breast, which is wanting in the male, 
as in the beautiful blue and white Halcyon diops of Ternate. 
In others the band is rufous in the female, as in several of the 
American species ; while in Dacelo gaudichaudii, and others of 



VI A THEORY OF BIRDS' NESTS 125 

the same genus, the tail of the female is rufous, while that of 
the male is blue. In most kingfishers the nest is in a deep 
hole in the ground; in Tanysiptera it is said to be a hole 
in the nests of termites, or sometimes in crevices under over- 
hanging rocks. 

2. Motmots (Momotidss). In these showy birds the sexes 
are exactly alike, and the nest in a hole under ground. 

3. Puff-birds (Bucconidse). These birds are often gaily 
coloured; some have coral- red bills; the sexes are exactly 
alike, and the nest is in a hole in sloping ground. 

4. Trogons (Trogonidse). In these magnificent birds the 
females are generally less brightly coloured than the males, but 
are yet often gay and conspicuous. The nest is in a hole of a tree. 

5. Hoopoes (Upupidse). The barred plumage and long 
crests of these birds render them conspicuous. The sexes are 
exactly alike, and the nest is in a hollow tree. 

6. Hornbills (Bucerotidse). These large birds have enor- 
mous coloured bills, which are generally quite as well coloured 
and conspicuous in the females. Their nests are always in 
hollow trees, where the female is entirely concealed. 

7. Barbets (Capitonidse). These birds are all very gaily- 
coloured, and, what is remarkable, the most brilliant patches 
of colour are disposed about the head and neck, and are very 
conspicuous. The sexes are exactly alike, and the nest is in 
a hole of a tree. 

8. Toucans (Ehamphastidse). These fine birds are coloured 
in the most conspicuous parts of their body, especially on the 
large bill, and on the upper and lower tail coverts, which are 
crimson, white, or yellow. The sexes are exactly alike, and 
they always build in a hollow tree. 

9. Plaintain-eaters (Musophagidse). Here again the head 
and bill are most brilliantly coloured in both sexes, and the 
nest is in a hole of a tree. 

10. Ground cuckoos (Centropus). These birds are often 
of conspicuous colours, and are alike in both sexes. They 
build a domed nest. 

11. Woodpeckers (Picidse). In this family the females 
often differ from the males in having a yellow or white, 
instead of a crimson crest, but are almost as conspicuous. 
They all nest in holes in trees. 



126 NATURAL SELECTION vi 

12. Parrots (Psittaci). In this great tribe, adorned with 
the most brilliant and varied colours, the rule is that the 
sexes are precisely alike, and this is the case in the most 
gorgeous families, the lories, the cockatoos, and the macaws ; 
but in some there is a sexual difference of colour to a 
slight extent. All build in holes, mostly in trees, but some- 
times in the ground, or in white ants' nests. In the single 
case in which the nest is exposed, that of the Australian 
ground parrot, Pezoporus formosus, the bird has lost the gay 
colouring of its allies, and is clothed in sombre and completely 
protective tints of dusky green and black. 

13. Gapers (Eurylaemidse). In these beautiful Eastern 
birds, somewhat allied to the American chatterers, the sexes 
are exactly alike, and are adorned with the most gay and con- 
spicuous markings. The nest is a woven structure, covered over, 
and suspended from the extremities of branches over water. 

14. Pardalotus (Ampelidse). In these Australian birds 
the females differ from the males, but are often very con- 
spicuous, having brightly -spotted heads. Their nests are 
sometimes dome shaped, sometimes in holes of trees, or in 
burrows in the ground. 

15. Tits (Paridse). These little birds are always pretty, and 
many (especially among the Indian species) are very conspicuous. 
They always have the sexes alike, a circumstance very unusual 
among the smaller gaily-coloured birds of our own country. 
The nest is always covered over or concealed in a hole. 

16. Nuthatches (Sitta). Often very pretty birds, the 
sexes alike, and the nest in a hole. 

17. (Sittella). The female of these Australian nut- 
hatches is often the most conspicuous, being white and black 
marked. The nest is, according to Gould, " completely con- 
cealed among upright twigs connected together." 

18. Creepers (Climacteris). In these Australian creepers 
the sexes are alike, or the female most conspicuous, and the 
nest is in a hole of a tree. 

19. Estrelda, Amadina. In these genera of Eastern and 
Australian finches the females, although more or less different 
from the males, are still very conspicuous, having a red rump, 
or being white spotted. They differ from most others of the 
family in building domed nests. 



VI A THEORY OF BIRDS' NESTS 127 

20. Certhiola. In these pretty little American creepers 
the sexes are alite, and they build a domed nest. 

21. Mynahs (Sturnidse). These showy Eastern starlings 
have the sexes exactly alike. They build in holes of trees. 

22. Calornis (Sturnidse). These brilliant metallic starlings 
have no sexual differences. They build a pensile covered nest. 

23. Hangnests (Icteridse). The red or yellow and black 
plumage of most of these birds is very conspicuous, and is 
exactly alike in both sexes. . They are celebrated for their 
fine purse-shaped pensile nests. 

It will be seen that this list comprehends six important 
families of Fissirostres, four of Scansores, the Psittaci, and 
several genera, with three entire families of Passeres, com- 
prising about twelve hundred species, or about one-seventh of 
all known birds. 

The cases in which, whenever the male is gaily coloured, 
the female is much less gay or quite inconspicuous are ex- 
ceedingly numerous, comprising, in fact, almost all the bright- 
coloured Passeres, except those enumerated in the preceding 
class. The following are the most remarkable : — 

1. Chatterers (Cotingidae). These comprise some of the 
most gorgeous birds in the world, vivid blues, rich purples, 
and bright reds being the most characteristic colours. The 
females are always obscurely tinted, and are often of a 
greenish hue, not easily visible among the foliage. 

2. Manakins (Pipridse). These elegant birds, whose caps 
or crests are of the most brilliant colours, are usually of a 
sombre green in the female sex. 

3. Tanagers (Tanagridae). These rival the chatterers in 
the brilliancy of their colours, and are even more varied. The 
females are generally of plain and sombre hues, and always 
less conspicuous than the males. 

4. Sugar-birds (Coerebidse). The males are a beautiful 
blue ; the females green. 

5. Pheasants (Phasianidse). These include some of the 
most brilliant and gorgeously coloured birds in the world, 
such as the peacock, gold and silver pheasants, fire-backed 
pheasants, and many others ; but the females are always com- 
paratively dull coloured, and generally of highly protective tints. 



128 NATURAL SELECTION vi 

In the extensive families of the warblers (Sylviadse), 
thrushes (Turdidae), flycatchers (Muscicapidse), and shrikes 
(Laniadse), a considerable proportion of the species are beauti- 
fully marked with gay and conspicuous tints, but in every 
case the females are less gay, and are most frequently of the 
very plainest and least conspicuous hues. Now, throughout 
the whole of these families the nest is open, and I am not aware of 
a single instance in which any one of these birds builds a 
domed nest, or places it in a hole of a tree, or under ground, or in 
any place where it is effectually concealed. 

In considering the question we are now investigating, it is 
not necessary to take into account the larger and more power- 
ful birds, because they seldom depend much on concealment 
to secure their safety. In the raptorial birds bright colours 
are as a rule absent ; and their structure and habits are such 
as not to require any special protection for the female. The 
larger waders are sometimes very brightly coloured in both 
sexes ; but they are probably little subject to the attacks of 
enemies, since the scarlet ibis, the most conspicuous of birds, 
exist in immense quantities in South America. In game birds 
and water-fowl, however, the females are often very plainly 
coloured, when the males are adorned with brilliant hues ; 
and the abnormal family of the Megapodidse offers us the in- 
teresting fact of an identity in the colours of the sexes (which 
in Megacephalon and Talegalla are somewhat conspicuous), in 
conjunction with the habit of not sitting on the eggs at all. 

What the Facts Teach us * 

Taking the whole body of evidence here brought forward, 
embracing as it does almost every group of bright-coloured 
birds, it will, I think, be admitted that the relation between 
the two series of facts in the colouring and nidification of 
birds has been sufficiently established. There are, it is true, 
a few apparent and some real exceptions, which I shall con- 
sider presently ; but they are too few and unimportant to 
weigh much against the mass of evidence on the other side, 
and may for the present be neglected. Let us then consider 
what we are to do with this unexpected set of correspondences 
between groups of phenomena which, at first sight, appear so 
disconnected. Do they fall in with any other groups of 



VI A THEORY OF BIRDS' NESTS 129 

natural phenomena ? Do they teach us anything of the way 
in which nature works, and give us any insight into the 
causes which have brought about the marvellous variety, and 
beauty, and harmony of living things? I believe we can 
answer these questions in the afifirmative ; and I may mention, 
as a sufficient proof that these are not isolated facts, that I 
was first led to see their relation to each other by the study 
of an analogous though distinct set of phenomena among in- 
sects, that of protective resemblance and " mimicry." 

On considering this remarkable series of corresponding 
facts, the first thing we are taught by them seems to be, that 
there is no incapacity in the female sex among birds to receive 
the same bright hues and strongly contrasted tints with which 
their partners are so often decorated, since whenever they are 
protected and concealed during the period of incubation they 
are similarly adorned. The fair inference is, that it is chiefly 
due to the absence of protection or concealment during this 
important epoch, that gay and conspicuous tints are withheld 
or left undeveloped. The mode in which this has been effected 
is very intelligible, if we admit the action of natural and 
sexual selection. It would appear from the numerous cases 
in which both sexes are adorned with equally brilliant colours 
(while both sexes are rarely armed with equally developed 
offensive and defensive weapons when not required for indi- 
vidual safety), that the normal action of " sexual selection " or 
of other unknown causes, is to develop colour and beauty in 
both sexes, by the preservation and multiplication of all 
varieties of colour in either sex which are pleasing to the 
other. Several very close observers of the habits of animals 
have assured me that male birds and quadrupeds do often 
take very strong likes and dislikes to individual females, and 
we can hardly believe that the one sex (the female) can have 
a general taste for colour while the other ha,s no such taste. 
However this may be, the fact remains, that in a vast number 
of cases the female acquires as brilliant and as varied colours 
as the male, and therefore most probably acquires them in the 
same way as the male does — that is, either because the 
colour is useful to it, or is correlated with some useful varia- 
tion, or is pleasing to the other sex. The only remaining 
supposition is that it is transmitted from the other sex, with- 

K 



130 NATURAL SELECTION vi 

out being of any use. From the number of examples above 
adduced of bright colours in the female, this would imply that 
colour-characters acquired by one sex are generally (but not 
necessarily) transmitted to the other. If this be the case it 
will, I think, enable us to explain the phenomena, even if we 
do not admit that the male bird is ever influenced in the 
choice of a mate by her more gay or perfect plumage. 

The female bird, while sitting on her eggs in an uncovered 
nest, is much exposed to the attacks of enemies, and any 
modification of colour which rendered her more conspicuous 
would often lead to her destruction and that of her offspring. 
All variations of colour in this direction in the female would 
therefore sooner or later be eliminated, while such modifications 
as rendered her inconspicuous, by assimilating her to sur- 
rounding objects, as the earth or the foliage, would, on the 
whole, survive the longest, and thus lead to the attainment 
of those brown or green and inconspicuous tints, which form 
the colouring (of the upper surface at least) of the vast 
majority of female birds which sit upon open nests. 

This does not imply, as some have thought, that all female 
birds were once as brilliant as the males. The change has 
been a very gradual one, generally dating from the origin of 
genera or of larger groups, but there can be no doubt that 
the remote ancestry of birds having great sexual differences 
of colour were nearly or quite alike, sometimes (perhaps in 
most cases) more nearly resembling the female, but occasion- 
ally perhaps being nearer what the male is now. The young 
birds (which usually resemble the females) will probably give 
some idea of this ancestral type, and it is well known that 
the young of allied species and of different sexes are often 
undistinguishable. 

Colour more variable than Strudwre or Habits, and therefore the 
Character which has generally been Modified 

At the commencement of this essay I have endeavoured 
to prove that the characteristic differences and the essentia] 
features of birds' nests are dependent on the structure of the 
species and upon the present and past conditions of their 
existence. Both these factors are more important and less 
variable than colour ; and we must therefore conclude that in 



VI A THEORY OF BIRDS' NESTS 131 

most cases the mode of nidification (dependent on structure 
and environment) has been the cause, and not the eflfect, of 
the similarity or differences of the sexes as regards colour. 
When the confirmed habit of a group of birds was to build 
their nests in holes of trees like the toucans, or in holes in 
the ground like the kingfishers, the protection the female thus 
obtained, during the important and dangerous time of incuba- 
tion, placed the two sexes on an equality as regards exposure 
to attack, and allowed " sexual selection," or any other cause, 
to act unchecked in the development of gay colours and con- 
spicuous markings in both sexes. 

When, on the other hand (as in the tanagers and flycatchers), 
the habit of the whole group was to build open cup-shaped 
nests in more or less exposed situations, the production of 
colour and marking in the female, by whatever cause, was 
continually checked by its rendering her too conspicuous, while 
in the male it had free play, and developed in him the most 
gorgeous hues. This, however, was not perhaps universally 
the case ; for where there was more than usual intelligence 
and capacity for change of habits, the danger the female was 
exposed to by a partial brightness of colour or marking might 
lead to the construction of a concealed or covered nest, as in 
the case of the tits and hangnests. When this occurred, a 
special protection to the female would be no longer necessary; 
so that the acquisition of colour and the modification of the 
nest might in some cases act and react on each other and 
attain their full development together. 

Exceptional Cases confirmatory of the above Explanation 
There exist a few very curious and anomalous facts in the 
natural history of birds, which fortunately serve as crucial 
tests of the truth of this mode of explaining the inequalities 
of sexual coloration. It has been long known that in some 
species the males either assisted in, or wholly performed, the 
act of incubation. It has also been often noticed that in 
certain birds the usual sexual differences were reversed, the 
male being the more plainly coloured, the female more gay 
and often larger. I am not, however, aware that these two 
anomalies had ever been supposed to stand to each other in 
the relation of cause and effect, till I adduced them in support 



132 NATURAL SELECTION vi 

of my views of the general theory of protective adaptation. 
Yet it is undoubtedly the fact that in the best known cases 
in which the female bird is more conspicuously coloured than 
the male, it is either positively ascertained that the latter 
performs the duties of incubation, or there are good reasons 
for believing such to be the case. The most satisfactory 
example is that of the Gray Phalarope (Phalaropus f ulicarius), 
the sexes of which are alike in winter, while ip summer the 
female instead of the male takes on a gay and conspicuous 
nuptial plumage ; but the male performs the duties of incubation, 
sitting upon the eggs, which are laid upon the bare ground. 

In the dotterell (Eudromias morinellus) the female is 
larger and more brightly coloured than the male ; and here, 
also, it is almost certain that the latter sits upon the eggs. 
The turnices of India also have the female larger and often 
more brightly coloured ; and Mr. Jerdon states, in his Birds 
of India, that the natives report that, during the breeding 
season, the females desert their eggs and associate in flocks, 
while the males are employed in hatching the eggs. In the 
few other cases in which the females are more brightly 
coloured, the habits are not accurately known. The case of 
the ostriches and emeus will occur to many as a difficulty, 
for here the male incubates, but is not less conspicuous than 
the female ; but there are two reasons why the case does not 
apply : the birds are too large to derive any safety from 
concealment; from enemies which would devour the eggs 
they can defend themselves by force, while to escape from 
their personal foes they trust to speed. 

We find, therefore, that a very large mass of facts relating 
to the sexual coloration and the mode of nidification of birds, 
including some of the most extraordinary anomalies to be 
found in their natural history, can be shown to have an inter- 
dependent relation to each other, on the simple principle of 
the need of greater protection to that parent which performs 
the duties of incubation. Considering the very imperfect 
knowledge we possess of the habits of most extra-European 
birds, the exceptions to the prevalent rule are few, and gene- 
rally occur in isolated species or in small groups ; while several 
apparent exceptions can be shown to be really confirmations 
of the law. 



VI A THEORY OF BIRDS' NESTS 133 

Eeal or apparent Exceptions to the Law stated at page 124 

The only marked exceptions I have been able to discover 
are the following — 

1. King crows (Dicrourus). These birds are of a glossy 
black colour, with long forked tails. The sexes present no 
difference, and they build open nests. This apparent excep- 
tion may probably be accounted for by the fact that these 
birds do not need the protection of a less conspicuous colour. 
They are very pugnacious, and often attack and drive away 
crows, hawks, and kites ; and as they are semi-gregarious in 
their habits, the females are not likely to be attacked while 
incubating. 

2. Orioles (OrioUdae). The true orioles are very gay birds ; 
the sexes are, in many Eastern species, either nearly or quite 
alike, and the nests are open. This is one of the most serious 
exceptions, but it is one that to some extent proves the rule ; 
for in this case it has been noticed that the parent birds 
display excessive care and solicitude in concealing the nest 
among thick foliage, and in protecting their offspring by in- 
cessant and anxious watching. This indicates that the want 
of protection consequent on the bright colour of the female 
makes itself felt, and is obviated by an increased development 
of the mental faculties. 

3. Ground thrushes (Pittidse). These elegant and briUiantly- 
coloured birds are generally alike in both sexes, and buUd an 
open nest. It is curious, however, that this is only an ap- 
parent exception, for almost all the bright colours are on the 
under surface, the back being usually olive-green or brown, 
and the head black, with brown or whitish stripes, all which 
colours would harmonise with the foliage, sticks, and roots 
which surround the nest, built on or near the ground, and 
thus serve as a protection to the female bird. 

4. Grallina AustraHs. This Australian bird is of strongly 
contrasted black and white colours. The sexes are exactly 
alike, and it builds an open clay nest in an exposed situation 
on a tree. This appears to be a most striking exception, but 
I am by no means sure that it is so. We require to know 
what tree it usually builds on, the colour of the bark or of 
the lichens that grow upon it, the tints of the ground, or of 



134 NATURAL SELECTION vl 

other surrounding objects, before we can say that the bird, 
when sitting on its nest, is really conspicuous. It has been 
remarked that small patches of white and black blend at a 
short distance to form gray, one of the commonest tints of 
natural objects. 

5. Sunbirds (Nectariniidse). In these beautiful little birds 
the males only are adorned with brilliant colours, the females 
being quite plain, yet they build covered nests in all the cases 
in which the nidification is known. This is a negative rather 
than a positive exception to the rule, since there may be other 
causes besides the need for protection which prevent the 
female acquiring the gay colours of her mate, and there is one 
curious circumstance which tends to elucidate it. The male 
of Leptocoma zeylanica is said to assist in incubation. It is 
possible, therefore, that the group may originally have used 
open nests, and some change of conditions, leading the male 
bird to sit, may have been followed by the adoption of a domed 
nest. This is, however, the most serious exception I have yet 
found to the general rule. 

6. Superb warblers (Maluridse). The males of these little 
birds are adorned with the most gorgeous colours, while the 
females are very plain, yet they make domed nests. It is to 
be observed, however, that the male plumage is nuptial 
merely, and is retained for a very short time ; the rest of 
the year both sexes are plain alike. It is probable, there- 
fore, that the domed nest is for the protection of these 
delicate little birds against the rain, and that there is some 
unknown cause which has led to the development of colour 
in the males only. 

There is one other case which at first sight looks like an 
exception, but which is far from being one in reality, and 
deserves to be mentioned. In the beautiful waxwing (Bom- 
bycilla garrula) the sexes are very nearly alike, and the 
elegant red wax tips to the wing-feathers are nearly, and 
sometimes quite, as conspicuous in the female as in the male. 
Yet it builds an open nest, and a person looking at the bird 
would say it ought, according to my theory, to cover its nest. 
But it is, in reality, as completely protected by its coloration 
as the most plainly coloured bird that flies. It breeds only 
in very high latitudes, and the nest, placed in fir-trees, is 



A THEORY OF BIRDS' NESTS 135 



formed chiefly of fir-twigs and lichens. Now the delicate 
gray and ashy and puiplish hues of the head and back, to- 
gether with the yellow of the wings and tail, are tints that 
exactly harmonise with the colours of fir leaves, bark, and 
lichens, while the brilliant red wax tips exactly represent the 
crimson fructification of the common lichen, Cladonia cocci- 
fera. When sitting on its nest, therefore, the female bird 
mil exhibit no colours that are not common to the materials 
by which it is surrounded ; and the several tints are distri- 
buted in about the same proportions as they occur in nature. 
At a short distance the bird would be undistinguishable from 
the nest it is sitting on, or from a natural clump of lichens, 
and will thus be completely protected. 

I think I have now noticed all exceptions of any import- 
ance to the law of dependence of sexual colour on nidification. 
It will be seen that they are very few in number, compared 
with those which support the generalisation ; and in several 
cases there are circumstances in the habits or structure of the 
species that sufficiently explain them. It is remarkable also 
that I have found scarcely any positive exceptions — that is, 
cases of very brilliant or conspicuous female birds in which 
the nest was not concealed. Much less can there be shown 
any group of birds in which the females are all of decidedly 
conspicuous colours on the upper surface, and yet sit in open 
nests. The many cases in which birds of dull colours in both 
sexes make domed or concealed nests do not, of course, affect 
this theory one way or the other ; since its purpose is only 
to account for the fact that brilliant females of brilliant 
males are always found to have covered or hidden nests, while 
obscure females of brilliant males almost always have open and 
exposed nests. The fact that all classes of nests occur with 
birds which are dull coloured in both sexes merely shows 
that these dull colours serve to protect the parents at other 
times than when sitting on the nest, the structure of which is 
determined by the requirements of the ofispring. 

If the views here advocated are correct, as to the various 
influences that have determined the specialities of every bird's 
nest, and the general coloration of female birds, with their 
action and reaction on each other, we can hardly expect to 
find evidence more complete than that here set forth. Nature 



136 NATURAL SELECTION vi 

is such a tangled web of complex relations, that a series of 
correspondences running through hundreds of species, genera, 
and families, in every part of the system, can hardly fail to 
indicate a true casual connection ; and when, of the two 
factors in the problem, one can be shown to be dependent on 
the most deeply seated and the most stable facts of structure 
and conditions of life, while the other is a character univer- 
sally admitted to be superficial and easily modified, there can 
be little doubt as to which is cause and which effect. 

Various modes of Protection of Animals 

But the explanation of the phenomenon here attempted 
does not rest alone on the facts I have been able now to 
adduce. In the essay on "Mimicry" it is shown how im- 
portant a part the necessity for protection has played, in 
determining the external form and coloration, and sometimes 
even the internal structure of animals. 

As illustrating this latter point, I may refer to the remark- 
able hooked, branched, or star-like spiculse in many sponges, 
which are believed to have the function chiefly of rendering 
them unpalatable to other creatures. The Holothuridse or 
sea- cucumbers possess a similar protection, many of them 
having anchor-shaped spicules embedded in their skin, as the 
Synapta ; while others (Cuviera squamata) are covered with a 
hard calcareous pavement. Many of these are of a bright red 
or purple colour, and are very conspicuous, while the allied 
Trepang, or Beche-de-mer (Holothuria edulis), which is not 
armed with any such defensive weapons, is of a dull sand or 
mud colour, so as hardly to be distinguished from the sea-bed 
on which it reposes. Many of the smaller marine animals are 
protected by their almost invisible transparency, while those 
that are most brightly coloured will be often found to have a 
special protection, either in stinging tentacles like Physalia, 
or in a hard calcareous crust, as in the star-fishes. 

Females of some Groups require and obtain more Protection 
than the Males 

In the struggle for existence incessantly going on, pro- 
tection or concealment is one of the most general and most 
effectual means of maintaining life ; and it is by modifications 



VI A THEORY OF BIRDS' NESTS 137 

of colour that this protection can be most readily obtained, 
since no other character is subject to such numerous and 
rapid variations. The case I have now endeavoured to illus- 
trate is exactly analogous to what occurs among butterflies. 
As a general rule, the female butterfly is of dull and incon- 
spicuous colours, even when the male is most gorgeously 
arrayed ; but when the species is protected from attack by a 
disagreeable odour and taste, as in the Heliconidse, Danaidae 
and Acrseidse, both sexes display the same or equally brilliant 
hues. Among the species which gain a protection by imitat- 
ing these, the very weak and slow-flying Leptalides resemble 
them in both sexes, because both sexes alike require pro- 
tection, while in the more active and strong-winged genera — 
Papilio, Pieris, and Diadema — it is generally the females only 
that mimic the protected groups, and in doing so often become 
actually more gay and more conspicuous than the males, thus 
reversing the usual and in fact almost universal characters of 
the sexes. So, in the wonderful Eastern leaf-insects of the 
genus PhylUum, it is the female only that so marvellously 
imitates a green leaf ; and in all these cases the difierence can 
be traced to the greater need of protection for the female, on 
whose continued existence, while depositing her eggs, the 
safety of the race depends. In Mammalia and in reptiles, 
however brilliant the colour may be, there is rarely any differ- 
ence between that of the sexes, because the female is not 
necessarily more exposed to attack than the male. It may, I 
think, be looked upon as a confirmation of this view, that no 
single case is known either in the above-named genera — 
Papilio, Pieris, and Diadema — or in any other butterfly, of a 
male alone mimicking one of the Danaidse or Heliconidse. 
Yet the necessary colour is far more abundant in the males, 
and variations always seem ready for any useful purpose. 
This seems to depend on the general law that each species 
and each sex can only be modified just as far as is absolutely 
necessary for it to maintain itself in the struggle for existence, 
not a step further. A male insect by its structure and habits 
is less exposed to danger, and also requires less protection, 
than the female. It cannot, therefore, alone acquire any 
further protection through the agency of natural selection. 
But the female requires some extra protection, to balance the 



138 NATURAL SELECTION vi 

greater danger to which she is exposed and her greater im- 
portance to the existence of the species ; and this she always 
acquires, in one way or another, through the action of natural 
selection. 

In his Origin of Species, fourth edition, p. 241, Mr. Darwin 
recognises the necessity for protection as sometimes being a 
cause of the obscure colours of female birds ; ^ but he does not 
seem to consider it so very important an agent in modifying 
colour as I am disposed to do. In the same paragraph (p. 
240) he alludes to the fact of female birds and butterflies 
being sometimes very plain, sometimes as gay as the males ; 
but, apparently, considers this mainly due to peculiar laws of 
inheritance, which sometimes continue acquired colour in the 
line of one sex only, sometimes in both. Without denying 
the action of such a law (which Mr. Darwin informs me he 
has facts to support), I impute the difference, in the great 
majority of cases, to the greater or less need of protection in 
the female sex in these groups of animals. 

This need was seen to exist a century ago by the Hon. 
Daines Harrington, who, in the article already quoted (see p. 
104), after alluding to the fact that singing birds are all small, 
and suggesting (but I think erroneously) that this may have 
arisen from the difficulty larger birds would have in conceal- 
ing themselves if they called the attention of their enemies by 
loud notes, goes on thus : " I should rather conceive it is for 
the same reason no hen bird sings, because this talent would 
be still more dangerous during incubation, which may possibly 
also accoimt for the inferiority in point of plumage.'' This is a 
curious anticipation of the main idea on which this essay is 
founded. It has been unnoticed for near a century, and my 
attention was only recently called to it by Mr. Darwin himself. 

Conclusion 

To some persons it will perhaps appear that the causes to 
which I impute so much of the external aspect of nature are 
too simple, too insignificant, and too unimportant for such a 
mighty work. But I would ask them to consider that the 
great object of all the peculiarities of animal structure is to 
preserve the life of the individual, and to maintain the exist- 

^ This passage is omitted in the sixth edition. 



vt A THEORY OF BIRDS' NESTS 139 

ence of tte species. Colour has hitherto been too often looked 
upon as something adventitious and superficial, something 
given to an animal not to be useful to itself, but solely to 
gratify man or even superior beings — to add to the beauty 
and ideal harmony of nature. If this were the case, then, it 
is evident that the colours of organised beings would be an 
exception to most other natural phenomena. They would not 
be the product of general laws, or determined by ever-chang- 
ing external conditions ; and we must give up all inquiry into 
their origin and causes, since (by the hypothesis) they are 
dependent on a Will whose motives must ever be unknown to 
us. But, strange to say, no sooner do we begin to examine 
and classify the colours of natural objects, than we find that 
they are intimately related to a variety of other phenomena, 
and are, like them, strictly subordinated to general laws. I 
have here attempted to elucidate some of these laws in the 
case of birds, and have shown how the mode of nidification 
has affected the colouring of the female sex in this group. I 
have before shown to how great an extent, and in how many 
ways, the need of protection has determined the colours of 
insects, and of some groups of reptUes and mammalia, and I 
would now call particular attention to the fact that the gay 
tints of flowers, so long supposed to be a convincing proof that 
coloiu- has been bestowed for other purposes than the good of 
its possessor, have been shown by Mr. Darwin to follow the 
same great law of utility. Flowers do not often need pro- 
tection, but very often require the aid of insects to fertilise 
them, and maintain their reproductive powers in the greatest 
vigour. Their gay colours attract insects, as do also their 
sweet odours and honeyed secretions ; and that this is the 
main function of colour in flowers is shown by the striking 
fact that those flowers which can be perfectly fertilised by 
the wind, and do not need the aid of insects, rarely or never 
have gaily-colowed flowers. 

This wide extension of the general principle of utility to 
the colours of such varied groups, both in the animal and 
vegetable kingdoms, compels us to acknowledge that the 
"reign of law" has been fairly traced into this stronghold of 
the advocates of special creation. And to those who oppose 
the explanation now given of the various facts bearing upon 



140 NATURAL SELECTION vi 

this subject, I would again respectfully urge that they must 
grapple with the whole of the facts, not one or two of them 
only. It wiU be admitted that, on the theory of evolution 
and natural selection, a wide range of facts with regard to 
colour in nature have been co-ordinated and explained. Until 
at least an equally wide range of facts can be shown to be in 
harmony with any other theory, we can hardly be expected 
to abandon that which has already done such good service, 
and which has led to the discovery of so many interesting 
and unexpected harmonies among the most common (but 
hitherto most neglected and least understood) of the phe- 
nomena presented by organised beings. 



YII 

CREATION BY LAW^ 

Among the various criticisms that have appeared on Mr. 
Darwin's celebrated Origin of Species, there is, perhaps, 
none that will appeal to so large a number of well educated 
and intelligent persons as that contained in the Duke of 
Argyll's Beigii of Law. The noble author represents the feel- 
ings and expresses the ideas of that large class of persons who 
take a keen interest in the progress of science in general, 
and especially that of Natural History, but have never them- 
selves studied nature in detail, or acquired that personal 
knowledge of the structure of closely allied forms, — the 
wonderful gradations from species to species and from group 
to group, and the infinite variety of the phenomena of " varia- 
tion" in organic beings, — which is absolutely necessary for 
a full appreciation of the facts and reasonings contained in 
Mr. Darwin's great work. 

Nearly half of the Duke's book is devoted to an exposition 
of his idea of " Creation by Law," and he expresses so clearly 
what are his difficulties and objections as regards the theory 
of " Natural Selection," that I think it advisable that they 
should be fairly answered, and that his own views should be 
shown to lead to conclusions as hard to accept as any which 
he imputes to Mr. Darwin. 

The point on which the Duke of Argyll lays most stress 
is, that proofs of Mind everywhere meet us in Nature, and 
are more especially manifest wherever we find " contrivance " 
or "beauty." He maintains that this indicates the constant 

^ First published in the Quarterly Jowmal of /Science, October 1868 ; 
reprinted in Contributions, etc., with a few alterations and additions. 



142 NATURAL SELECTIOK vii 

supervision and direct interference of the Creator, and 
cannot possibly be explained by the unassisted action of any 
combination of laws. Now, Mr. Darwin's work has for its 
main object to show that all the phenomena of living things, 
— aU their wonderful organs and complicated structures, their 
infinite variety of form, size, and colour, their intricate and 
involved relations to each other, — may have been produced 
by the action of a few general laws of the simplest kind, laws 
which are in most cases mere statements of admitted facts. 
The chief of these laws or facts are the following : — 

1. The Law of Multiplication in Geometrical Progression. — 
AU organised beings have enormous powers of multiplication. 
Even man, who increases slower than aU other animals, could 
under the most favourable circumstances double his numbers 
every fifteen years, or a hundredfold in a century. Many 
animals and plants could increase their numbers from ten to 
a thousandfold every year. 

2. The Law of Limited Populations. — The number of living 
individuals of each species in any country, or in the whole 
globe, is practically stationary; whence it follows that the 
whole of this enormous increase must die off almost as fast 
as produced, except only those individuals for whom room is 
made by the death of parents. As a simple but striking 
example, take an oak forest. Every oak will drop annually 
many thousands of acorns, but till an old tree falls not one 
of the millions of acorns produced can grow up into an oak. 
They must die at various stages of growth. 

3. The Law of Heredity, or Likeness of Offspring to their 
Parents. — This is a universal, but not an absolute law. All 
creatures resemble their parents in a high degree, and in the 
majority of cases very accurately; so that even individual 
peculiarities, of whatever kind, in the parents, are almost 
always transmitted to some of the offspring. 

4. The Law of Variation. — This is fully expressed by the 

lines : — 

" No being on this earthly ball, 
Is like another, all in all." 

Offspring resemble their parents very much, but not wholly 
— each being possesses its individuality. This "variation" 
itself varies in amount, but it is always present, not only in 



VII CREATION BY LAW 143 

the whole organism, but in every part of each organism. 
Every organ, every character, every feeling, is individual; 
that is to say, varies from the same organ, character, or feeling 
in every other individual. 

5. ITie Law of unceasing Change of Physical Conditions wpon 
the Surface of the Emth. — Geology shovi^s us that this change 
has always gone on in times past, and we also know that it 
is now everywhere going on. 

6. The Equilibrium or Harmony of Nature. — When a species 
is well adapted to the conditions which environ it, it flourishes ; 
when imperfectly adapted it decays ; when ill -adapted it 
becomes extinct. If all the conditions which determine an 
organism's wellbeing are taken into consideration, this state- 
ment can hardly be disputed. 

This series of facts or laws are mere statements of what 
is the condition of nature. They are facts or inferences which 
are generally known, generally admitted — but, in discussing 
the subject of the "Origin of Species," as generally for- 
gotten. It is from these universally admitted facts that the 
origin of all the varied forms of nature may be deduced by 
a logical chain of reasoning, which, however, is at every step 
verified and shown to be in strict accord with facts ; and, at 
the same time, many curious phenomena which can by no 
other means be understood are explained and accounted for. 
It is probable that these primary facts or laws are but results 
of the very nature of Ufe, and of the essential properties of 
organised and unorganised matter. Mr. Herbert Spencer, in 
his First Principles and his Biology, has, I think, made us able 
to understand how this may be ; but at present we may 
accept these simple laws without going further back, and the 
question then is — whether the variety, the harmony, the 
contrivance, and the beauty we perceive in organic beings 
can have been produced by the action of these laws alone, or 
whether we are required to believe in the incessant interfer- 
ence and direct action of the mind and will of the Creator. 
It is simply a question of how the Creator has worked. The 
Duke (and I quote him as having well expressed the views 
of the more intelligent of Mr. Darwin's opponents) maintains 
that He has personally applied general laws to produce effects 



144 NATURAL SELECTION vn 

which those laws are not in themselves capable of producing ; 
that the universe alone, with all its laws intact, would be 
a sort of chaos, without variety, without harmony, without 
design, without beauty; that there is not (and therefore we 
may presume that there could not be) any self- developing 
power in the universe. I believe, on the contrary, that the 
universe is so constituted as to be self-regulating; that as 
long as it contains Life, the. forms under which that life is 
manifested have an inherent power of adjustment to each 
other and to surrounding nature ; and that this adjustment 
necessarily leads to the greatest amount of variety and beauty 
and enjoyment, because it does depend on general laws, and 
not on a continual supervision and rearrangement of details. 
As a matter of feeling and religion, I hold this to be a far 
higher conception of the Creator and of the Universe than 
that which may be called the " continual interference " 
hypothesis ; but it is not a question to be decided by our 
feelings or convictions — it is a question of facts and of reason. 
Could the change which geology shows us has continually 
taken place in the forms of life, have been produced by general 
laws, or does it imperatively require the incessant supervision 
of a creative mind ! This is the question for us to consider, 
and our opponents have the difficult task of proving a nega- 
tive, if we show that there are both facts and analogies in 
our favour.^ 

Mr. Darmn's Metaphors liable to Misconception 

Mr. Darwin has laid himself open to much misconception, 
and has given to his opponents a powerful weapon against 
himself, by his continual use of metaphor in describing the 
wonderful co-adaptations of organic beings. 

" It is curious," says the Duke of Argyll, " to observe the 
language which this most advanced disciple of pure naturalism 
instinctively uses, when he has to describe the complicated 
structure of this curious order of plants (the Orchids). 
' Caution in ascribing intentions to nature ' does not seem to 

' In addition to the laws referred to above, there are of course the funda- 
mental laws and properties of organised matter and the mysterious powers of 
Life, which we shall probably never be able to explain, but which must be 
taken as the basis of all attempts to account for the details of form and 
structure in organised beings. 



CREATION BY LAW 145 



occur to him as possible. Intention is the one thing which 
he does see, and which, when he does not see, he seeks for 
diligently until he finds it. He exhausts every form of words 
and of illustration, by which intention or mental purpose can 
be described. ' Contrivance ' — 'curious contrivance,' — 'beauti- 
ful contrivance,' — these are expressions which occur over and 
over again. Here is one sentence describing the parts of a 
particular species: 'The labellum is developed into a long 
nectary, in order to attract Lepidoptera, and we shall presently 
give reason for suspecting that the nectar is purposely so 
lodged that it can be sucked only slowly in order to give time 
for the curious chemical quaKty of the viscid matter setting 
hard and dry.' " Many other examples of similar expressions 
are quoted by the Duke, who maintains that no explanation 
of these " contrivances " has been or can be given, except on 
the supposition of a personal contriver, specially arranging 
the details of each case, although causing them to be produced 
by the ordinary processes of growth and reproduction. 

Now there is a difficulty in this view of the origin of the 
structure of Orchids which the Duke does not allude to. The 
majority of ilowering plants are fertilised, either without the 
agency of insects or, when insects are required, without any 
very important modification of the structure of the flower. 
It is evident, therefore, that flowers might have been formed 
as varied, fantastic, and beautiful as the orchids, and yet have 
been fertilised without more complexity of structure than is 
found in violets, or clover, or primroses, or a thousand other 
flowers. The strange springs and traps and pitfalls found in 
the flowers of orchids cannot be necessary per se, since exactly 
the same end is gained in ten thousand other flowers which 
do not possess them. Is it not then an extraordinary idea, to 
imagine the Creator of the universe contriving the various 
complicated parts of these flowers, as a mechanic might con- 
trive an ingenious toy or a difficult puzzle ? Is it not a more 
worthy conception that they are some of the results of those 
general laws which were so co-ordinated at the first intro- 
duction of life upon the earth as to result necessarily in the 
utmost possible development of varied forms ? 

But let us take one of the simpler cases adduced and see 
if our general laws are unable to account for it. 

L 



146 NATURAL SELECTION Vii 



A Case of Orchid-structure explained by Natural Selection 

There is a Madagasca^orcliid — the Angrsecum sesquipedale 
— with an immensely long and deep nectary. How did such 
an extraordinary organ come to be developed ? Mr. Darwin's 
explanation is this. The pollen of this flower can only be 
removed by the base of the proboscis of some very large 
moths, when trying to get at the nectar at the bottom of the 
vessel. The moths with the longest probosces would do this 
most effectually; they would be rewarded for their long 
tongues by getting the most nectar ; whilst on the other hand, 
the flowers with the deepest nectaries would be the best 
fertilised by the largest moths preferring them. Conse- 
quently, the deepest nectaried orchids and the longest tongued 
moths would each confer on the other an advantage in the 
battle of life. This would tend to their respective perpetua- 
tion, and to the constant lengthening of nectaries and pro- 
bosces. Now let it be remembered that what we have to 
account for is only the unusual length of this organ. A nec- 
tary is found in many orders of plants and is especially 
common in the orchids, but in this one case only is it some- 
times more than a foot long. How did this arise ? We begin 
with the fact, proved experimentally by Mr. Darwin, that 
moths do visit orchids, do thrust their spiral trunks into the 
nectaries, and do fertilise them by carrying the poUinia of one 
flower to the stigma of another. He has further explained 
the exact mechanism by which this is effected, and the Duke 
of Argyll admits the accuracy of his observations. In our 
British species, such as Orchis pyramidalis, it is not necessary 
that there should be any exact adjustment between the length 
of the nectary and that of the proboscis of the insect ; and 
thus a number of insects of various sizes are found to carry 
away the poUinia and aid in the fertilisation. In the 
Angrsecum sesquipedale, however, it is necessary that the 
proboscis should be forced into a particular part of the flower, 
and this would only be done by a large moth burying its pro- 
boscis to the very base, and straining to drain the nectar from 
the bottom of the long tube, in which it occupies a depth of 
one or two inches only. Now let us start from the time when 
the nectary was only half its present length or about six 



CREATION BY LAW 147 



inches, and was chiefly fertilised by a species of moth which 
appeared at the time of the plant's flowering, and whose pro- 
boscis was of the same length. Among the millions of flowers 
of the Angraecum produced every year, some would always be 
shorter than the average, some longer. The former, owing 
to the structure of the flower, would not get fertilised, be- 
cause the moths could get all the nectar without forcing their 
trunks down to the very base. The latter would be well 
fertilised, and the longest would on the average be the best 
fertilised of all. By this process alone the average length 
of the nectary would annually increase, because, the short- 
nectaried flowers being sterile and the long ones having 
abundant offspring, exactly the same effect would be produced 
as if a gardener destroyed the short ones and sowed the seed 
of the long ones only ; and this we know by experience 
would produce a regular increase of length, since it is this 
very process which has increased the size and changed the 
form of our cultivated fruits and flowers. 

But this would lead in time to such an increased length 
of the nectary that many of the moths could only just reach 
the surface of the nectar, and only the few with exceptionally 
long trunks be able to suck up a considerable portion. 

This would cause many moths to neglect these flowers 
because they could not get a satisfying supply of nectar, and 
if these were the only moths in the country the flowers would 
undoubtedly suffer, and the further growth of the nectary be 
checked by exactly the same process which had led to its 
increase. But there are an immense variety of moths, of 
various lengths of proboscis, and as the nectary became longer, 
other and larger species would become the fertilisers, and 
would carry on the process till the largest moths became the 
sole agents. Now, if not before, the moth would also be 
affected, for those with the longest probosces would get most 
food, would be the strongest and most vigorous, would visit 
and fertilise the greatest number of flowers, and would leave 
the largest number of descendants. The flowers most com- 
pletely fertilised by these moths being those which had the 
longest nectaries, there would in each generation be on the 
average an increase in the length of the nectaries, and also 
an average increase in the length of the probosces of the 



148 NATURAL SELECTION vii 

moths ; and this would be a necessary result from the fact that 
nature ever fluctuates ahout a mean, or that in every genera- 
tion there would be flowers with longer and shorter nectaries, 
and moths with longer and shorter probosces than the average. 
No doubt there are a hundred causes that might have checked 
this process before it had reached the point of development 
at which we find it. If, for instance, the variation in the 
quantity of nectar had been at any stage greater than the 
variation in the length of the nectary, then smaller moths 
could have reached it and have effected the fertilisation. Or 
if the growth of the probosces of the moths had from other 
causes increased quicker than that of the nectary, or if the 
increased length of proboscis had been injurious to them in 
any way, or if the species of moth with the longest proboscis 
had become much diminished by some enemy or other un- 
favourable conditions, then, in any of these cases, the shorter 
nectaried flowers, which would have attracted and could have 
been fertilised by the smaller kinds of moths, would have had 
the advantage. And checks of a similar nature to these no 
doubt have acted in other parts of the world, and have pre- 
vented such an extraordinary development of nectary as has 
been produced by favourable conditions in Madagascar only, 
and in one single species of orchid. I may here mention that 
some of the large Sphinx moths of the tropics have probosces 
nearly as long as the nectary of Angrsecum sesquipedale. I 
have carefully measured the proboscis of a specimen of Macro- 
sila cluentius from South Ajnerica, in the collection of the British 
Museum, and find it to be nine inches and a quarter long ! 
One from tropical Africa (Macrosila morganii) is seven inches 
and a half. A species having a proboscis two or three inches 
longer could reach the nectar in the largest flowers of Angrse- 
cum sesquipedale, whose nectaries vary in length from ten 
to fourteen inches. That such a moth exists in Madagascar 
may be safely predicted ; and naturalists who visit that island 
should search for it with as much confidence as astronomers 
searched for the planet Neptune, — and I venture to predict 
they will be equally successful ! 

Now, instead of this beautiful self-acting adjustment, the 
opposing theory is, that the Creator of the universe, by a 
direct act of His will, so disposed the natural forces influencing 



CREATION BY LAW 149 



the growth of this one species of plant as to cause its nectary 
to increase to this enormous length ; and at the same time, 
by an equally special act, determined the flow of nourishment 
in the organisation of the moth, so as to cause its proboscis to 
increase in exactly the same proportion, having previously so 
constructed the Angrsecum that it could only be maintained 
in existence by the agency of this moth. But what proof is 
given or suggested that this was the mode by which the ad- 
justment took place ? None whatever, except a feeling that 
there is an adjustment of a delicate kind, and an inability to 
see how known causes could have produced such an adjust- 
ment. I believe I have sho^vn, however, that such an 
adjustment is not only possible but inevitable, unless at some 
point or other we deny the action of those simple laws which 
we have already admitted to be but the expressions of exist- 
ing facts. 

Adaptation brought about by General Laws 

It is difficult to find anything like parallel cases in inorganic 
nature, but that of a river may perhaps illustrate the subject 
in some degree. Let us suppose a person totally ignorant of 
modern geology to study carefully a great river system. He 
finds in its lower part a deep broad channel filled to the 
brim, flowing slowly through a flat country and carrying out 
to the sea a quantity of fine sediment. Higher up it branches 
into a number of smaller channels, flowing alternately through 
flat valleys and between high banks ; sometimes he finds a 
deep rocky bed with perpendicular walls, carrying the water 
through a chain of hills ; where the stream is narrow he finds 
it deep, where wide shallow. Farther up still, he comes to a 
mountainous region, with hundreds of streams and rivulets, 
each with its tributary rills and gullies, collecting the water 
from every square mile of surface, and every channel adapted 
to the water that it has to carry. He finds that the bed of 
every branch and stream and rivulet has a steeper and 
steeper slope as it approaches its sources, and is thus enabled 
to carry off the water from heavy rains, and to bear away 
the stones and pebbles and gravel that would otherwise block 
up its course. In every part of this system he would see 
exact adaptation of means to an end. He would say that 
this system of channels must have been designed, it answers 



150 NATURAL SELECTION vn 

its purpose so effectually. Nothing but a mind could have so 
exactly adapted the slopes of the channels, their capacity, and 
frequency, to the nature of the soil and the quantity of the 
rainfall. Again, he would see special adaptation to the wants 
of man, in broad, quiet, navigable rivers flowing through fertile 
plains that support a large population, while the rocky streams 
and mountain torrents were confined to those sterile regions 
suitable only for a small population of shepherds and herds- 
men. He would listen with incredulity to the geologist who 
assured him that the adaptation and adjustment he so admired 
was an inevitable result of the action of general laws ; that 
the rains and rivers,' aided by subterranean forces, had 
modelled the country, had formed the hiUs and valleys, had 
scooped out the river beds and levelled the plains ; and it 
would only be after much patient observation and study, 
after having watched the minute changes produced year by 
year, and multiplying them by thousands and ten thousands, 
— after visiting the various regions of the earth and seeing the 
changes everywhere going on, and the unmistakable signs of 
greater changes in past times, — that he could be made to 
understand that the surface of the earth, however beautiful 
and harmonious it may appear, is strictly due in every detail 
to the action of forces which are demonstrably self-adjusting. 
Moreover, when he had sufficiently extended his inquiries, 
he would find that every evil effect which he would imagine 
must be the result of non-adjustment does somewhere or other 
occur, only it is not always evil. Looking on a fertile valley, 
he would perhaps say : " If the channel of this river were not 
well adjusted — if for a few miles it sloped the wrong way — 
the water could not escape, and all this luxuriant valley, full of 
human beings, would become a waste of waters." Well, there 
are hundreds of such cases. Every lake is a valley " wasted 
by water," and in some cases (as the Dead Sea) it is a positive 
evil, a blot upon the harmony and adaptation of the surface 
of the earth. Again, he might say — "If rain did not fall 
here, but the clouds passed over us to some other regions, 
this verdant and highly cultivated plain would become a 
desert." And there are such deserts over large portions of 
the earth, which abundant rains would convert into pleasant 
dwelling-places for man. Or he might observe some great 



CREATION BY LAW 151 



navigable river, and reflect how easily rocks, or a steeper 
channel in places, might render it useless to manj — and a 
little inquiry would show him hundreds of rivers in every 
part of the world, which are thus rendered useless for 
navigation. 

Exactly the same thing occurs in organic nature. We see 
some one wonderful case of adjustment, some unusual develop- 
ment of an organ, but we pass over the hundreds of cases in 
which that adjustment and development do not occur. No 
doubt when one adjustment is absent another takes its place, 
because no organism can continue to exist that is not adjusted 
to its environment ; and unceasing variation, with unlimited 
powers of multiplication, in most cases, furnishes the means 
of self-adjustment. The world is so constituted that by the 
action of general laws there is produced the greatest possible 
variety of surface and of climate ; and by the action of laws 
equally general, the greatest possible variety of organisms has 
been produced, adapted to the varied conditions of every part of 
the earth. The objector would probably himself admit that 
the varied surface of the earth — the plains and valleys, the 
hiUs and mountains, the deserts and volcanoes, the viands and 
currents, the seas and lakes and rivers, and the various 
climates of the earth — are all the results of general laws 
acting and reacting during countless ages; and that the 
Creator does not appear to guide and control the action of 
these laws — here determining the height of a mountain, there 
altering the channel of a river — here making the rains more 
abundant, there changing the direction of a current. He 
would probably admit that the forces of inorganic nature are 
self-adjusting, and that the result necessarily fluctuates about 
a given mean condition (which is itself slowly changing), while 
vnthin certain limits the greatest possible amount of variety 
is produced. If then a " contriving mind " is not necessary 
at every step of the process of change eternally going on in 
the inorganic world, why are we required to believe in the con- 
tinual action of such a mind in the region of organic nature 1 
True, the laws at work are more complex, the adjustments 
more delicate, the appearance of special adaptation more 
remarkable ; but why should we measure the creative mind 
by our own? Why should we suppose the machine too 



152 NATURAL SELECTION vii 

complicated to have been designed by the Creator so com- 
plete that it would necessarily work out harmonious results ? 
The theory of " continual interference " is a limitation of the 
Creator's power. It assumes that He could not work by pure 
law in the organic, as He has done in the inorganic world ; it 
assumes that He could not foresee the consequences of the laws 
of matter and mind combined — that results would continually 
arise which are contrary to what is best — and that He has to 
change what would otherwise be the course of nature in order 
to produce that beauty, and variety, and harmony which even 
we, with our limited intellects, can conceive to be the result 
of self-adjustment in a universe governed by unvarying law. 
If we could not conceive the world of nature to be self-adjust- 
ing and capable of endless development, it would even then 
be an unworthy idea of a Creator to impute the incapacity of 
our minds to Him; but when many human minds can conceive, 
and can even trace out in detail, some of the adaptations in 
nature as the necessary results of unvarying law, it seems 
strange that, in the interests of religion, any one should seek 
to prove that the System of Nature, instead of being above, 
is far below our highest conceptions of it. I, for one, cannot 
believe that the world would come to chaos if left to law 
alone. I cannot believe that there is in it no inherent power 
of developing beauty or variety, and that the direct action of 
the Deity is required to produce each spot or streak on every 
insect, each detail of structure in every one of the millions of 
organisms that live or have lived upon the earth. For it is 
impossible to draw a line. If any modiiications of structure 
could be the result of law, why not all ? If some self-adapta- 
tions could arise, why not others ? If any varieties of colour, 
why not all the varieties we see? No attempt is made to 
explain this, except by reference to the fact that " purpose " 
and " contrivance " are everywhere visible, and by the illo- 
gical deduction that they could only have arisen from the 
direct action of some mind, because the direct action of our 
minds produces similar " contrivances " ; but it is forgotten 
that adaptation, however produced, must have the appearance 
of design. The channel of a river looks as if made fvr the 
river, although it is made hy it ; the fine layers and beds in a 
deposit of sand often look as if they had been sorted, and 



CREATION BY LAW 163 



sifted, and levelled designedly; the sides and angles of a 
crystal exactly resemble similar forms designed by man ; but 
we do not therefore conclude that these effects have, in each 
individual case, required the directing action of a creative 
mind, or see any difl&culty in their being produced by natural 
law. 

Beauty in Nature 

Let us, however, leave this general argument for a while, 
and turn to another special case, which has been appealed to 
as conclusive against Mr. Darwin's views. "Beauty" is, to 
some persons, as great a stumbling-block as "contrivance." 
They cannot conceive a system of the universe so perfect as 
necessarily to develop every form of beauty, but suppose that 
when anything specially beautiful occurs, it is a step beyond 
what that system could have produced — something which the 
Creator has added for his own delectation. 

Speaking of the humming birds, the Duke of Argyll says : 
" In the first place it is to be observed of the whole group, 
that there is no connection which can be traced or conceived, 
between the splendour of the humining birds and any function 
essential to their Ufe. If there were any such connection, 
that splendour could not be confined, as it almost exclusively 
is, to only one sex. The female birds are, of course, not 
placed at any disadvantage in the struggle for existence by 
their more sombre colouring." And after describing the 
various ornaments of these 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 pur- 
poses 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 attain- 
ment of them. There seems to be no conceivable reason why 
we should doubt or question that these are ends and aims 



154 NATURAL SELECTION vn 

also in the forms given to living organisms " {Beign of Law, 
p. 248). 

Here the statement that " no connection can be conceived 
between the splendour of the humming birds and any function 
essential to their life," is met by the fact that Mr. Darwin 
has not only conceived but has shown, both by observation 
and reasoning, how beauty of colour and form may have a 
direct influence on the most important of all the functions of 
life, that of reproduction. In the variations to which birds 
are subject, any more brilliant colour than usual is believed 
to be attractive to the females, and would therefore lead to 
the individuals so adorned leaving more than the average 
number of oifspring. There are some indications that this kind 
of sexual selection does actually take place, and the laws of 
inheritance would necessarily lead to the further development 
of any individual peculiarity that was attractive, and thus the 
splendour of the humming birds is directly connected with 
their very existence. It is true that " a crest of topaz may 
be no better than a crest of sapphire," but either of these may 
be much better than no crest at all ; and the different condi- 
tions under which the parent form must have existed in 
different parts of its range will have determined different 
variations of tint, either of which were advantageous. ■■■ The 
reason why female birds are not adorned with equally brilliant 
plumes is sufficiently clear ; they would be injurious by ren- 
dering their possessors too conspicuous during incubation. 
Survival of the fittest has therefore favoured the development 
of those dark green tints on the upper surface of so many 
female humming birds, which are most conducive to their 
protection while the important functions of hatching and 
rearing the young are being carried on. Keeping in mind 
the laws of multiplication, variation, and survival of the 
fittest, which are for ever in action, these varied develop- 

^ Since ■writing this essay I have come to the conclusion that mere 
diversity of colouring hetween species is an important factor in their differ- 
entiation, serving as a means of recognition, and thus preventing cross- 
unions. See Danmnism, p. 217. I have also heen led to doubt the reality 
of the fact of female selection of slight differences of colour on which Mr. 
Darwin relied, hut it has not been thought advisable to alter the passages 
which seem to admit it, as they represent my belief at the time they were 
written. 



CREATION BY LAW 155 



ments of beauty and harmonious adjustments to conditions 
are not only conceivable but demonstrable results. 

The objection I am now combating is solely founded on 
the supposed analogy of the Creator's mind to ours as regards 
the love of beauty for its own sake ; but if this analogy is to 
be trusted, then there ought to be no natural objects which 
are disagreeable or ungraceful in our eyes. And yet it is 
undoubtedly the fact that there are many such. Just as 
surely as the horse and deer are beautiful and graceful, the 
elephant, rhinoceros, hippopotamus, and camel are the reverse. 
The majority of monkeys and apes are not beautiful ; the 
majority of birds have no beauty of colour ; a vast number of 
insects and reptiles are positively ugly. Now, if the Creator's 
mind is like ours, whence this ugliness ? It is useless to say 
" that is a mystery we cannot explain," because we have 
attempted to explain one-half of creation by a method that 
will not apply to the other half. We know that a man with 
the highest taste and with unlimited wealth practically does 
abolish aU ungraceful and disagreeable forms and colours from 
his own domains. If the beauty of creation is to be explained 
by the Creator's love of beauty, we are bound to ask why He 
has not banished deformity from the earth, as the wealthy and 
enlightened man does from his estate and from his dwelling ; 
and if we can get no satisfactory answer, we shall do well to 
reject the explanation offered. Again, in the case of flowers, 
which are always especially referred to as the surest evidence 
of beauty being an end of itself in creation, the whole of the 
facts are never fairly met. At least half the plants in the 
world have not bright-coloured or beautiful flowers ; and Mr. 
Darwin has lately arrived at the wonderful generalisation 
that flowers have become beautiful solely to attract insects to 
assist in their fertilisation. He adds, "I have come to this 
conclusion from finding it an invariable rule, that when a 
flower is fertilised by the wind it never has a gaily-coloured 
corolla." Here is a most wonderful case of beauty being 
useful, when it might be least expected. But much more is 
proved ; for when beauty is of no use to the plant it is not 
given. It cannot be imagined to do any harm. It is simply 
not necessary, and is therefore withheld ! We ought surely 
to have been told how this fact is consistent with beauty 



156 NATURAL SELECTION vii 

being " an end in itself," and with the statement of its being 
given to natural objects " for its own sake." 

How New Forms are produced by Variation and Selection 

Let us now consider another of the popular objections 
which the Duke of Argyll' thus sets forth : — 

"Mr. Darwin does not pretend to have discovered any 
law or rule, according to which new forms have been born 
from old forms. He does not hold that outward conditions, 
however changed, are sufficient to account for them. . . . His 
theory seems to be far better than a mere theory — to be an 
established scientific truth — in so far as it accounts, in part at 
least, for the success and establishment and spread of new 
forms when they have arisen. But it does not even suggest the 
law under which, or by or according to which, such new forms 
are introduced. Natural Selection can do nothing, except 
with the materials presented to its hands. It cannot select 
except among the things open to selection. . . . Strictly 
speaking, therefore, Mr. Darwin's theory is not a theory on 
the Origin of Species at all, but only a theory on the causes 
which lead to the relative success or failure of such new forms 
as may be born into the world" {Reign of Law, p. 230). 

In this and many other passages in his work the Duke 
of Argyll sets forth his idea of creation as a " creation by 
birth," but maintains that each birth of a new form from 
parents differing from itself has been produced by a special 
interference of the Creator, in order to direct the process of 
development into certain channels ; that each new species is 
in fact a " special creation," although brought into existence 
through the ordinary laws of reproduction. He maintains, 
therefore, that the laws of multiplication and variation cannot 
furnish the right kinds of materials at the right times for 
natural selection to work on. I believe, on the contrary, 
that it can be logically ^tow(^ from the six axiomatic laws 
before laid down, that such materials would be furnished ; but 
I prefer to show there are abundance of facts which demon- 
strate that they are furnished. 

The experience of all cultivators of plants and breeders of 
animals shows that, when a sufficient number of individuals 
are examined, variations of any required kind can always be 



CREATION BY LAW 157 



met with. On this depends the possibility of obtaining 
breeds, races, and fixed varieties of animals and plants ; and it 
is found that any one form of variation may be accumulated 
by selection, without materially affecting the other characters 
of the species ; each seems to vary in the one required direction 
only. For example, in turnips, radishes, potatoes, and carrots 
the root or tuber varies in size, colour, form, and flavour, while 
the foliage and flowers seem to remain almost stationary ; ia 
the cabbage and lettuce, on the contrary, the foliage can be 
modified into various forms and modes of growth, the root, 
flower, and fruit remaining little altered ; in the cauliflower 
and broccoli the flower heads vary ; in the garden pea the pod 
only changes. We get innumerable forms of fruit in the 
apple and pear, while the leaves and flowers remain almost 
undistinguishable ; the same occurs in the gooseberry and 
garden currant. Directly, however (in the very same genus), 
we want the flower to vary in the Eibes sanguineum, it does 
so, although mere cultivation for hundreds of years has not 
produced marked differences in the flowers of Eibes grossu- 
laria. When fashion demands any particular change in the 
form, or size, or colour of a flower, sufiicient variation always 
occurs in the right direction, as is shown by our roses, auri- 
culas, and geraniums ; when, as recently, ornamental leaves 
come into fashion, sufficient variation is foimd to meet the 
demand, and we have zoned pelargoniums and variegated 
ivy, and it is discovered that a host of our commonest shrubs 
and herbaceous plants have taken to vary in this direction 
just when we want them to do so ! This rapid variation is 
not confined to old and well-known plants subjected for a long 
series of generations to cultivation, but the Sikkim rhodo- 
dendrons, the fuchsias, and calceolarias from the Andes, and 
the pelargoniums from the Cape, are equally accommodating, 
and vary just when and where and how we require them. 

Turning to animals we find equally striking examples. 
If we want any special quality in any animal we have only to 
breed it ia sufficient quantities and watch carefully, and the 
required variety is always found, and can be increased to 
almost any desired extent. In sheep, we get flesh, fat, and 
wool; in cows, milk; in horses, colour, strength, size, and 
speed ; in poultry, we have got almost any variety of colour, 



158 NATURAL SELECTION vii 

curious modifications of plumage, and the capacity of per- 
petual egg-laying. In pigeons we have a still more remark- 
able proof of the universality of variation, for it has been at 
one time or another the fancy of breeders to change the form 
of every part of these birds, and they have never found the 
required variations absent. The form, size, and shape of bill 
and feet have been changed to such a degree as is found only 
in distinct genera of wild birds ; the number of tail feathers 
has been increased, a character which is generally one of the 
most permanent nature, and is of high importance in the 
classification of birds ; and the size, the colour, and the habits 
have been also changed to a marvellous extent. In dogs, 
the degree of modification and the facility with which it is 
effected is almost equally apparent. Look at the constant 
amount of variation in opposite directions that must have 
been going on to develop the poodle and the greyhound from 
the same original stock ! Instincts, habits, intelligence, size, 
speed, form, and colour have always varied, so as to produce 
the very races which the wants or fancies or passions of 
men may have led them to desire. Whether they wanted a 
bull-dog to torture another animal, a greyhound to catch a 
hare, or a bloodhound to hunt down their oppressed fellow- 
creatures, the required variations have always appeared. 

Now this great mass of facts, of which a mere sketch has 
been here given, are fully accounted for by the "Law of 
Variation " as laid down at the commencement of this paper. 
Universal variability — small in amount, but in every direction, 
ever fluctuating about a mean condition until made to advance 
in a given direction by " selection," natural or artificial — is 
the simple basis for the indefinite modification of the forms 
of life ; partial, unbalanced, and consequently unstable modi- 
fications being produced by man, while those developed under 
the unrestrained action of natural laws are at every step self- 
adjusted to external conditions by the dying out of all 
unadjusted forms, and are therefore stable and comparatively 
permanent.^ To be consistent in their views, our opponents 
must maintain that every one of the variations that have 
rendered possible the changes produced by man have been 

^ That the variations ooourring among wild animals are ample both in num- 
ber and amount is proved in Dimnnism, chap. iii. 



CREATION BY LAW 159 



determined at tte right time and place by the will of the 
Creator. Every race produced by the florist or the breeder, 
the dog or the pigeon fancier, the ratcatcher, the sporting man, 
or the slave-hunter, must have been provided for by varieties 
occurring when wanted ; and as these variations were never 
withheld, it would prove that the sanction of an all -wise 
and all-powerful Being has been given to that which the 
highest human minds consider to be trivial, mean, or debasing. 
This appears to be a complete answer to the theory that 
variation sufficient in amount to be accumulated in a given 
direction must be the direct act of the creative mind, but it is 
also sufficiently condemned by being so entirely unnecessary. 
The facility with which man obtains new races depends chiefly 
upon the number of individuals he can procure to select from. 
When hundreds of florists or breeders are all aiming at the 
same object, the work of change goes on rapidly. But a 
common species in nature contains a thousand or a million- 
fold moje individuals than any domestic race ; and survival 
of the fittest must unerringly preserve all that vary in the 
right direction, not only in obvious characters but in minute 
details — not only in external but in internal organs ; so that if 
the materials are sufficient for the needs of man, there can be 
no want of them to fulfil the grand purpose of keeping up a 
supply of modified organisms, exactly adapted to the changed 
conditions that are always occurring in the inorganic world. 

The Objection that there are Limits to Variation 

Having now, I believe, fairly answered the chief objections 
of the Duke of Argyll, I proceed to notice one or two of those 
adduced in an able and argumentative essay on the " Origin 
of Species" in the North British Review for July 1867. The 
writer first attempts to prove that there are strict limits to 
variation. When we begin to select variations in any one 
direction, the process is comparatively rapid, but after a con- 
siderable amount of change has been efi'ected it becomes 
slower and slower, till at length its limits are reached and no 
care in breeding and selection can produce any further advance. 
The racehorse is chosen as an example. It is admitted that, 
with any ordinary lot of horses to begin with, careful selection 
would in a few years make a great improvement, and in a 



160 NATURAL SELECTION vii 

comparatively short time the standard of our best racers might 
be reached. But that standard has not for many years been 
materially raised, although unlimited wealth and energy are 
expended in the attempt. This is held to prove that there 
are definite limits to variation in any special direction, and 
that we have no reason to suppose that mere time, and the 
selective process being carried on by natural law, could make 
any material difference. But the writer does not perceive 
that this argument fails to meet the real question, which is, 
not whether indefinite and unlimited change in any or all 
directions is possible, but whether such differences as do occur 
in nature could have been produced by the accumulation of 
variations by selection. In the matter of speed, a limit of a 
definite kind as regards land animals does exist in nature. 
All the swiftest animals — deer, antelopes, hares, foxes, lions, 
leopards, horses, zebras, and many others — have reacheci very 
nearly the same degree of speed. Although the swiftest of 
each must have been for ages preserved, and the slowest must 
have perished, we have no reason to believe there is any 
advance of speed. The possible limit under existing con- 
ditions, and perhaps under possible terrestrial conditions, has 
been long ago reached. In cases, however, where this limit had 
not been so nearly reached as in the horse, we have been 
enabled to make a more marked advance and to produce a 
greater difference of form. The wild dog is an animal that 
hunts much in company, and trusts more to endurance than 
to speed. Man has produced the greyhound, which differs 
much more from the wolf or the dingo than the racer does 
from the wild Arabian. Domestic dogs, again, have varied 
more in size and in form than the whole family of Canidse in 
a state of nature. No wild dog, fox, or wolf is either so 
small as some of the smallest terriers and spaniels, or so large 
as the largest varieties of hound or Newfoundland dog. And, 
certainly, no two wild animals of the family differ so widely 
in form and proportions as the Chinese pug and the Italian 
greyhound, or the bulldog and the common greyhound. The 
known range of variation is, therefore, more than enough for 
the derivation of all the forms of dogs, wolves, and foxes 
from a common ancestor. 

Again, it is objected that the pouter or the fan-tail pigeon 



CREATION BY LAW 161 



cannot be further developed in the same direction. ' Variation 
seems to have reached its limits in these birds. But so it has 
in nature. The fantaU has not only more tail feathers than 
any of the three hundred and sixty existing species of pigeons, 
but more than any of the ten thousand known species of birds. 
There is, of course, some limit to the number of feathers of 
which a tail usefid for flight can consist, and in the fantail we 
have probably reached that limit. Many birds have the 
oesophagus or the skin of the neck more or less dilatable, but 
in no known bird is it so dilatable as in the pouter pigeon. 
Here again the possible Hmit, compatible- with a healthy 
existence, has probably been reached. In Hke manner the 
differences in the size and form of the beak in the various 
breeds of the domestic pigeon is greater than that between 
the extreme forms of beak in the various genera and sub- 
families of the whole pigeon tribe. From these facts, and many 
others of the same nature, we may fairly infer that if rigid 
selection were applied to any organ, we could in a comparatively 
short time produce a much greater amount of change than 
that which occurs between species and species in a state of 
nature, since the differences which we do produce are often 
comparable with those which exist between distinct genera or 
distinct families. The facts adduced by the writer of the 
article referred to, of the definite limits to variability in certain 
directions in domesticated animals, are, therefore, no objection 
whatever to the view that all the modifications which exist in 
nature have been produced by the accumulation, by natural 
selection, of small and useful variations, since those very 
modifications have equally definite and very similar limits. 

Objection to the Argumevi from, Classification 

To another of this writer's objections — ^that by Professor 
Thomson's calculations the sun can only have existed in a 
solid state 500,000,000 of years, and that therefore time 
would not suffice for the slow process of development of all 
living organisms — it is hardly necessary to reply, as it cannot 
be seriously contended, even if this calculation has claims to 
approximate accuracy, that the process of change and develop- 
ment may not have been sufficiently rapid to have occurred 
within that period. His objection to the classification argu 



162 NATURAL SELECTION vii 

ment is, however, more plausible. The uncertainty of opinion 
among naturalists as to which are species and which varieties, 
is one of Mr. Darwin's very strong arguments that these two 
names cannot belong to things quite distinct in nature and 
origin. The reviewer says that this argument is of no weight, 
because the works of man present exactly the same phenomena ; 
and he instances patent inventions, and the excessive difficulty 
of determining whether they are new or old. I accept the 
analogy, though it is a very imperfect one, and maintain that, 
such as it is, it is all in favour of Mr. Darwin's views. For 
are not all inventions of the same kind directly affiliated to a 
common ancestor ? Are not improved steam-engines or clocks 
the lineal descendants of some existing steam-engine or clock 1 
Is there ever a new creation in art or science any more than 
in nature? Did ever patentee absolutely originate any 
complete and entire invention, no portion of which was 
derived from anything that had been made or described 
before ? It is therefore clear that the difficulty of distin- 
guishing the various classes of inventions which claim to be 
new, is of the same nature as the difficulty of distinguish- 
ing varieties and species, because neither are absolutely new 
creations, but both are alike descendants of pre-existing forms, 
from which and from each other they differ by varying and 
often imperceptible degrees. It appears, then, that however 
plausible this writer's objections may seem, whenever he 
descends from generalities to any specific statement, his 
supposed difficulties turn out to be in reality strongly con- 
firmatory of Mr. Darwin's view. 

The Times on Natural Selection 

The extraordinary misconception of the whole subject by 
popular writers and reviewers is well shown by an article 
which appeared in the Times newspaper on "The Eeign of 
Law." Alluding to the supposed economy of nature, in the 
adaptation of each species to its own place and its special use, 
the reviewer remarks : "To this universal law of the greatest 
economy, the law of natural selection stands in direct 
antagonism as the law of ' greatest possible waste ' of time 
and of creative power. To conceive a duck with webbed feet 
and a spoon-shaped bill, living by suction, to pass naturally 



CREATION BY LAW 168 



into a gull witk webbed feet and a knife-like bill, living on 
ilesh, in the longest possible time and in the most laborious 
possible way, we may conceive it to pass from the one to the 
other state by natural selection. The battle of life the ducks 
will have to fight will increase in peril continually as they 
cease (with the change of their biU) to be ducks, and attain a 
maximum of danger in the condition in which they begin to 
be gulls ; and ages must elapse and whole generations must 
perish, and countless generations of the one species be created 
and sacrificed, to arrive at one single pair of the other." 

In this passage the theory of natural selection is so absurdly 
misrepresented that it would be amusing, did we not consider 
the misleading efiect likely to be produced by this kind of 
teaching in so popular a journal. It is assumed that the duck 
and the gull are essential parts of nature, each well fitted for its 
place, and that if one had been produced from the other by 
a gradual metamorphosis, the intermediate forms would have 
been useless, unmeaning, and unfitted for any place in the 
system of the universe. Now, this idea can only exist in a 
mind ignorant of the very foundation and essence of the 
theory of natural selection, which is, the preservation of useful 
variations only, or, as has been well expressed, in other words, 
the " survival of the fittest." Every intermediate form which 
could possibly have arisen during the transition from the duck 
to the guU, so far from having an unusually severe battle to 
fight for existence, or incurring any "maximum of danger," 
would necessarily have been as accurately adjusted to the rest 
of nature, and as well fitted to maintain and to enjoy its 
existence, as the duck or the gull actually are. If it were not 
so, it never could have been produced under th^ law of natural 
selection. 

Intermediate or generalised Forms of extinct Animals, an 
indication of Transmutation or Demloprrient 

The misconception of this writer illustrates another point 
very frequently overlooked. It is an essential part of Mr. 
Darwin's theory that one existing animal has not been 
derived from any other existing animal, but that both are the 
descendants of a common ancestor, which was at once difierent 
from either, but, in essential characters, to some extent inter- 



164 NATURAL SELECTION va 

mediate between them both. The illustration of the duck 
and the gull is therefore misleading ; one of these birds has 
not been derived from the other, but both from a common 
ancestor. This is not a mere supposition invented to support 
the theory of natural selection, but is founded on a variety of 
indisputable facts. As we go back into past time, and meet 
with the fossil remains of more and more ancient races of 
extinct animals, we find that many of them actually are 
intermediate between distinct groups of existing animals. 
Professor Owen continually dwells on this fact : he says in 
his Palceontdogy, p. 284 : "A more generalised vertebrate 
structure is illustrated, in the extinct reptiles, by the affinities 
to ganoid fishes, shown by Ganocephala, Labyrinthodontia, and 
Ichthyopterygia ; by the afiSnities of the Pterosauria to birds, 
and \)j the approximation of the Dinosauria to mammals. 
(These have been recently shown by Professor Huxley to 
have more affinity to birds.) It is manifested by the combina- 
tion of modern crocodilian, chelonian, and lacertian characters 
in the Cryptodontia and the Dicynodontia, and by the com- 
bined lacertian and crocodilian characters in the Thecodontia 
and Sauropterygia." In the same work he tells us that " the 
Anoplotherium, in several important characters, resembled 
the embryo Euminant, but retained throughout life those 
marks of adhesion to a generalised mammalian type ; " and 
assures us that he has " never omitted a proper opportunity 
for impressing the results of observations showing the more 
generalised structures of extinct as compared with the more 
specialised forms of recent animals." Modern palaeontologists 
have discovered hundreds of examples of these more generalised 
or ancestral types. In the time of Cuvier, the Ruminants 
and the Pachyderms were looked upon as two of the most 
distinct orders of animals ; but it is now demonstrated that 
there once existed a variety of genera and species, connecting 
by almost imperceptible grades such widely different animals 
as the pig and the camel. Among living quadrupeds we can 
scarcely find a more isolated group than the genus Equus, 
comprising the horses, asses, and zebras ; but through many 
species of Paloplotherium, Hippotherium, and Hipparion, and 
numbers of extinct forms of Equus found in Europe, India, 
and America, an almost complete transition is established with 



CREATION BY LAW 165 



the Eocene Anoplotherium and Paleotherium, which are also 
generalised or ancestral types of the tapir and rhinoceros. 
The recent researches of M. Gaudry in Greece have furnished 
much new evidence of the same character. In the Miocene 
(or Pliocene) beds of Pikermi he has discovered the group of 
the Simocyonidaa intermediate between bears and wolves ; the 
genus Hysenictis which connects the hyaenas with the civets ; 
the Ancylotherium, which is allied both to the extinct mas- 
todon and to the living pangolin or scaly ant-eater; and 
the Helladotherium, which connects the now isolated giraffe 
with the deer and antelops. 

Between reptiles and fishes an intermediate type has been 
found in the Archegosaurus of the Coal formation ; while the 
Labyrinthodon of the Trias combined characters of the 
Batrachia with those of crocodiles, lizards, and ganoid fishes. 
Even birds, the most apparently isolated of all living forms, 
and the most rarely preserved in a fossil state, have been 
shown to possess undoubted aflSnities with reptiles; and in 
the Oolitic Archaeopteryx, with its lengthened tail, feathered 
on each side, we have one of the connecting links from the 
side of birds ; while Professor Huxley has recently shown 
that the entire order of Dinosaurians have remarkable aflBnities 
to birds, and that one of them, the Compsognathus, makes a 
nearer approach to bird organisation than does Archaeopteryx 
to that of reptiles. 

Analogous facts to these occur in other classes of animals, 
as an example of which we have the authority of a distin- 
guished paleontologist, M. Barande, quoted by Mr. Darwin, for 
the statement that although the Palaeozoic Invertebrata can 
certainly be classed under existing groups, yet at this ancient 
period the groups were not so distinctly separated from each 
other as they are now; while Mr. Scudder tells us that 
some of the fossil insects discovered in the Coal formation 
of America offer characters intermediate between those of 
existing orders. Agassiz, again, insists strongly that the 
more ancient animals resemble the embryonic forms of 
existing species ; but as the embryos of distinct groups are 
known to resemble each other more than the adult animals 
(and in fact to be undistinguishable at a very early age), this 
is the same as saying that the ancient animals are exactly 



166 



NATURAL SELECTION 



vil 



what, on Darwin's theory, the ancestors of existing animals 
ought to he ; and this, it must be remembered, is the evidence 
of one of the strongest opponents of the theory of natural 
selection. 

Oondusion 

I have thus endeavoured to meet fairly, and to answer 
plainly, a few of the most common objections to the theory of 
natural selection, and I have done so in every case by refer- 
ring to admitted facts and to logical deductions from those 
facts. 

As an indication and general summary of the line of 
argument I have adopted, I here give a brief demonstration 
in a tabular form of the Origin of Species by means of Natural 
Selection, referring for the facts to Mr. Darwin's works, and 
to the pages in this volume, where they are more or less fully 
treated. 



A Demmstration of the Origin of Species by Natwral Selection 



proved facts 

Rapid Inoeease oe Orqauisms, 
pp. 23, 142 (Origin of Species, 
p. 75, 5th ed.) 

Total Number of Inditidttals 
Stationaet, p. 23. 

Stkuggle foe Existence. 

Heredity with Variation, or 
general likeness with individual 
differences of parents and off- 
springs, pp. 142, 156, 179 {Origin 
of Species, chaps, i. ii. v.) 



Survival of the Fittest. 

Change of External Conditions, 
universal and unceasing. — See 
Lyell's Principles of Geology. 



NECESSARY CONSEQUENCES 
(afterwards taken as Proved Facts) 

Struggle for Existence, the 
deaths equalling the births on 
the average, p. 24 {Origin of 
Spedes, chap. iii. ) 

Survival of the Fittest, or 
Natural .Selection ; meaning, 
simply, that on the whole those 
die who are least fitted to main- 
tain their existence {Origin of 
Species, chap, iv.) 

Changes of Organic Forms, to 
keep them in harmony with the 
Changed Conditions ; and as the 
changes of conditions are perman- 
ent changes, in the sense of not 
reverting back to identical pre- 
vious conditions, the changes of 
organic forms must be in the 
same sense permanent, and thus 
originate Species. 



VIII 

THE DEVELOPMENT OF HUMAN RACES UNDER THE LAW OF 
NATURAL SELECTION^ 

Among the most advanced students of man there exists a 
wide diflference of opinion on some of the most vital questions 
respecting his nature and origin. Anthropologists are now, 
indeed, pretty well agreed that man is not a recent introduc- 
tion into the earth. AU who have studied the question now 
admit that his antiquity is very great ; and that, though 
we have to some extent ascertained the minimum of time 
during which he must have existed, we have made no approxi- 
mation towards determining that far greater period during which 
he may have, and probably has existed. We can with toler- 
able certainty aflBrm that man must have inhabited the earth a 
thousand centuries ago, but we cannot assert that he positively 
did not exist, or that there is any good evidence against his 
having existed, for a period of ten thousand centuries. We 
know positively that he was contemporaneous with many now 
extinct animals, and has survived changes of the earth's 
surface fifty or a hundred times greater than any that have 
occurred during the historical period; but we cannot place 
any definite Hmit to the number of species he may have 
outlived, or to the amount of terrestrial change he may 
have witnessed. 

Wide differences of opinion as to Man's Origin 
But while on this question of man's antiquity there is a 
very general agreement, — and all are waiting eagerly for 

' First puUished in the Anthropological Review, May 1864 ; reprinted in 
Contributions, etc., with some alterations and additions. 



168 NATURAL SELECTION viii 

fresh evidence to clear up those points which all admit to be 
full of doubt, — on other and not less obscure and difficult 
questions a considerable amount of dogmatism is exhibited ; 
doctrines are put forward as established truths, no doubt or 
hesitation is admitted, and it seems to be supposed that no 
further evidence is required, or that any new facts can 
modify our convictions. This is especially the case when we 
inquire, — Are the various forms under which man now 
exists primitive, or derived from pre-existing forms; in 
other words, is man of one or many species ? To this ques- 
tion we immediately obtain distinct answers diametrically 
opposed to each other : the one party positively maintaining 
that man is a species and is essentially one — that aU differences 
are but local and temporary variations, produced by the 
diflferent physical and moral conditions by which he is 
surrounded; the other party maintaining with equal con- 
fidence that man is a genus of many species, each of which 
is practically unchangeable, and has ever been as distinct, or 
even more distinct, than we now behold them. This differ- 
ence of opinion is somewhat remarkable, when we consider 
that both parties are well acquainted vnth the subject ; both 
use the same vast accumulation of facts ; both reject those 
early traditions of mankind which profess to give an account 
of his origin ; and both declare that they are seeking fear- 
lessly after truth alone ; yet each will persist in looking only 
at the portion of truth on his own side of the question, and at 
the error which is mingled with his opponent's doctrine. It 
is my wish to show how the two opposing views can be com- 
bined, so as to eliminate the error and retain the truth in 
each, and it is by means of Mr. Darwin's celebrated theory 
of Natural Selection that I hope to do this, and thus to har- 
monise the conflicting theories of modern anthropologists. 

Let us first see what each party has to say for itself. In 
favour of the unity of mankind it is argued that there are 
no races vrithout transitions to others; that every race 
exhibits vnthin itself variations of colour, of hair, of feature, 
and of form, to such a degree as to bridge over, to a large 
extent, the gap that separates it from other races. It is 
asserted that no race is homogeneous ; that there is a tend- 
ency to vary; that climate, food, and habits produce, and 



VIII THE DEVKLOPMENT OF HUMAN RACES 169 

render permanent, physical peculiarities, which, though slight 
in the limited periods allowed to our observation, would, in 
the long ages during which the human race has existed, have 
sufficed to produce all the diiferences that now appear. It is 
•further asserted that the advocates of the opposite theory do 
not agree among themselves ; that some would make three, 
some five, some fifty or a hundred and fifty species of man ; 
some would have had each species created in pairs, while 
others require nations to have at once sprung into existence, 
and that there is no stability or consistency in any doctrine 
but that of one primitive stock. 

The advocates of the original diversity of man, on the 
other hand, have much to say for themselves. They argue 
that proofs of change in man have never been brought for- 
ward except to the most trifling amount, while evidence of 
his permanence meets us everywhere. The Portuguese and 
Spaniards, settled for two or three centuries in South 
America, retain their chief physical, mental, and moral 
characteristics ; the Dutch boers at the Cape, and the de- 
scendants of the early Dutch settlers in the Moluccas, have 
not lost the features or the coloui- of the Germanic races ; 
the Jews, scattered over the world in the most diverse 
climates, retain the same characteristic lineaments every- 
where ; the Egyptian sculptures and paintings show us that, 
for at least 4000 or 5000 years, the strongly contrasted 
features of the Negro and the Semitic races have remained 
altogether unchanged; while more recent discoveries prove 
that the mound-builders of the Mississippi valley, and the 
dwellers on Brazilian mountains, had, even in the very infancy 
of the human race, some traces of the same peculiar and 
characteristic type of cranial formation that now distinguishes 
them. 

If we endeavour to decide impartially on the merits of 
this difficult controversy, judging solely by the evidence that 
each party has brought forward, it certainly seems that the 
best of the argument is on the side of those who maintain 
the primitive diversity of man. Their opponents have not 
been able to refute the permanence of existing races as far 
back as we can trace them, and have failed to show, in a 
single case, that at any former epoch the well marked varie- 



170 NATURAL SELECTION viit 

ties of mankind approximated more closely than they do at 
the present day. At the same time this is but negative 
evidence. A condition of immobility for four or five thou- 
sand years does not preclude an advance at an earlier epoch, 
and — if we can show that there are causes in nature ■which 
would check any further physical change when certain con- 
ditions were fulfilled — does not even render such an advance 
improbable, if there are any general arguments to be adduced 
in its favour. Such a cause, I believe, does exist ; and I 
shall now endeavour to point out its nature and its mode of 
operation. 

Outline of the Theory of Natwral Selection 

In order to make my argument intelligible, it is necessary 
for me to explain very briefly the theory of natural selec- 
tion promulgated by Mr. Darwin, and the power which it 
possesses of modifying the forms of animals and plants. The 
grand feature in the multiplication of organic life is, that 
close general resemblance is combined with more or less 
individual variation. The child resembles its parents or 
ancestors more or less closely in all its peculiarities, deformi- 
ties, or beauties ; it resembles them in general more than it 
does any other individuals ; yet children of the same parents 
are not all alike, and it often happens that they difier very 
considerably from their parents and from each other. This 
is equally true of man, of all animals, and of all plants. 
Moreover, it is found that individuals do not differ from their 
parents in certain particulars only, while in all others they 
are exact duplicates of them. They differ from them and 
from each other in every particular : in form, in size, in 
colour ; in the structure of internal as well as of external 
organs ; in those subtle peculiarities which produce difierences 
of constitution, as well as in those still more subtle ones 
which lead to modifications of mind and character. In other 
words, in every possible way, in every organ, and in every 
function, individuals of the same stock vary. 

Now, health, strength, and long life are the results of a 
harmony between the individual and the universe that sur- 
rounds it. Let us suppose that at any given moment this 
harmony is perfect. A certain animal is exactly fitted to 



THE DEVELOPMENT OF HUMAN RACES 171 



secure its prey, to escape from its enemies, to resist the 
inclemencies of the seasons, and to rear a numerous and 
healthy oifspring. But a change now takes place. A series 
of cold winters, for instance, come on, making food scarce, 
and bringing an immigration of some other animals to com- 
pete with the former inhabitants of the district. The new 
immigrant is swift of foot, and surpasses its rivals in the 
pursuit of game ; the winter nights are colder, and require a 
thicker fur as a protection, and more nourishing food to keep 
up the heat of the system. Our supposed perfect animal is 
no longer in harmony with its universe ; it is in danger of 
dying of cold or of starvation. But the animal varies in its 
offspring. Some of these are swifter than others — they still 
manage to catch food enough; some are hardier and more 
thickly furred — they manage in the cold nights to keep warm 
enough; the slow, the weak, and the thinly clad soon die 
off. Again and again, in each succeeding generation, the 
same thing takes place. By this natural process, which is so 
inevitable that it cannot be conceived not to act, those best 
adapted to Hve, live ; those least adapted, die. It is some- 
times said that we have no direct evidence of the action of 
this selecting power in nature. But it seems to me we have 
better evidence than even direct observation would be, 
because it is more universal, viz., the evidence of necessity. 
It must be so ; for, as all wild animals increase in a geomet- 
rical ratio, while their actual numbers remain on the 
average stationary, it follows that as many die annually as 
are born. If, therefore, we deny natural selection, it can 
only be by asserting that, in such a case as I have supposed, 
the strong, the healthy, the swift, the well clad, the well 
organised animals in every respect, have no advantage over 
— do not on the average live longer than — the weak, the 
unhealthy, the slow, the ill-clad, and the imperfectly organised 
individuals ; and this no sane man has yet been found hardy 
enough to assert. But this is not all ; for the offspring on 
the average resemble their parents, and the selected portion 
of each succeeding generation will therefore be stronger, 
swifter, and more thickly furred than the last ; and if this 
process goes on for thousands of generations, our animal will 
have again become thoroughly in harmony with the new con- 



172 NATURAL SELECTION vin 

ditions in 'which it is placed. But it will now be a different 
creature. It will be not only swifter and stronger, and more 
furry — it will also probably have changed in colour, in form, 
perhaps have acquired a longer tail, or differently shaped 
ears ; for it is an ascertained faot that when one part of an 
animal is modified, some other parts almost always change, 
as it were in sympathy with it. Mr. Darwin calls this 
" correlation of growth," and gives as instances that hairless 
dogs have imperfect teeth ; white cats, when blue-eyed, are 
deaf ; small feet accompany short beaks in pigeons ; and other 
equally interesting cases. 

Grant, therefore, the premises: 1st, That peculiarities of 
every kind are more or less hereditary; 2d, That the ofi'- 
spring of every animal vary more or less in all parts of their 
organisation ; 3d, That the universe in which these animals 
Live is not absolutely invariable; — none of which proposi- 
tions can be denied ; and then consider that the animals in 
any country (those at least which are not dying out) must at 
each successive period be brought into harmony with the 
surrounding conditions ; and we have aU the elements for a 
change of form and structure in the animals, keeping exact 
pace with changes of whatever nature in the surrounding 
universe. Such changes must be slow, for the changes in the 
universe are very slow ; but just as these slow changes be- 
come important, when we look at results after long periods 
of action, — as we do when we perceive the alterations of the 
earth's surface during geological epochs, — so the parallel 
changes in animal form become more and more striking, in 
proportion as the time they have been going on is great ; as 
we see when we compare our living animals with those 
which we disentomb from each successively older geological 
formation. 

This is, briefly, the theory of natural selection, which 
explains the changes in the organic world as being parallel 
with, and in part dependent on, those in the inorganic. What 
we now have to inquire is, Can this theory be appUed in 
any way to the question of the origin of the races of man ? or 
is there anything in human nature that takes him out of the 
category of those organic existences over whose successive 
mutations it has had such powerful sway ? 



THE DEVELOPMENT OF HUMAN RACES 173 



Different Effects of Natural Selection on Animals and on Ma/n 

In order to answer these questions, we must consider why 
it is that natural selection acts so powerfully upon animals, 
and we shall, I believe, find that its effect depends mainly 
upon their self-dependence and individual isolation. A slight 
injury, a temporary illness, will often end in death, because 
it leaves the individual powerless against its enemies. If an 
herbivorous animal is a little sick and has not fed well for a 
day or two, and the herd is then pursued by a beast of prey, 
our poor invalid inevitably falls a victim. So, in a carnivor- 
ous animal, the least deficiency of vigour prevents its captur- 
ing food, and it soon dies of starvation. There is, as a 
general rule, no mutual assistance between adults, which 
enables them to tide over a period of sickness. Neither is 
there any division of labour; each must fulfil ail the con- 
ditions of its existence, and, therefore, natural selection 
keeps all up to a pretty uniform standard. 

But in man, as we now behold him, this is different. He 
is social and sympathetic. In the rudest tribes the sick are 
assisted, at least with food; less robust health and vigour 
than the average does not entail death. Neither does the 
want of perfect limbs or other organs produce the same effects 
as among animals. Some division of labour takes place ; the 
swiftest hunt, the less active fish, or gather fruits ; food is, to 
some extent, exchanged or divided. The action of natural 
selection is therefore checked ; the weaker, the dwarfish, those 
of less active limbs, or less piercing eyesight, do not suffer the 
extreme penalty which falls upon animals so defective. 

In proportion as these physical characteristics become of 
less importance, mental and moral qualities will have increas- 
ing influence on the well-being of the race. Capacity for 
acting in concert for protection, and for the acquisition of 
food and shelter ; sympathy, which leads aU in turn to assist 
each other; the sense of right, which checks depredations 
upon our fellows ; the smaller development of the combative 
and destructive propensities ; self-restraint in present appe- 
tites, and that intelligent foresight which prepares for the 
future, are all qualities that from their earliest appearance 
must have been for the benefit of each community, and would, 



174 NATURAL SELECTION vm 

therefore, have become the subjects of natural selection. 
For it is evident that such qualities would be for the well- 
being of man, would guard him against external enemies, 
against internal dissensions, and against the effects of incle- 
ment seasons and impending famine, more surely than could 
any merely physical modification. Tribes in which such 
mental and moral qualities were predominant would there- 
fore have an - advantage in the struggle for existence over 
other tribes in which they were less developed — would live 
and maintain their numbers, while the others would decrease 
and finally succumb. 

Again, when any slow changes of physical geography or 
of climate make it necessary for an animal to alter its food, 
its clothing, or its weapons, it can only do so by the occur- 
rence of a corresponding change in its own bodily structure 
and internal organisation. If a larger or more powerful 
beast is to be captured and devoured, as when a carnivorous 
animal which has hitherto preyed on antelopes is obliged from 
their decreasing numbers to attack buffaloes, it is only the 
strongest who can hold, — those with most powerful claws 
and formidable canine teeth that can struggle with and over- 
come such an animal. Natural selection immediately comes 
into play, and by its action these organs gradually become 
adapted to their new requirements. But man, under similar 
circumstances, does not require longer nails or teeth, greater 
bodily strength or swiftness. He makes sharper spears, or a 
better bow, or he constructs a cunning pitfall, or combines in 
a hunting party to circumvent his new prey. The capacities 
which enable him to do this are what he requires to be 
strengthened, and these will, therefore, be gradually modified 
by natural selection, while the form and structure of his 
body will remain unchanged. So, when a glacial epoch comes 
on, some animals must acquire warmer fur, or a covering of 
fat, or else die of cold. Those best clothed by nature are, 
therefore, preserved by natural selection. Man, under the 
same circumstances, will make himself warmer clothing, and 
build better houses, and the necessity of doing this will react 
upon his mental organisation and social condition — will ad- 
vance them while his natural body remains naked as before. 

When the accustomed food of some animal becomes scarce 



VIII THE DEVELOPMENT OF HUMAN RACES 175 

or totally fails, it can only exist by becoming adapted to a new 
kind of food, a food perhaps less nourishing and less digestible. 
Natural selection will now act upon the stomach and intes- 
tines, and all their individual variations will be taken advan- 
tage of, to modify the race into harmony with its new food. 
In many cases, however, it is probable that this cannot be 
done. The internal organs may not vary quick enough, and 
then the animal will decrease in numbers and finally become 
extinct. But man guards himself from such accidents by 
superintending and guiding the operations of nature. He 
plants the seed of his most agreeable food, and thus procures 
a supply, independent of the accidents of varying seasons or 
natural extinction. He domesticates animals, which serve him 
either to capture food or for food itself, and thus changes of 
any great extent in his teeth or digestive organs are rendered 
unnecessary. Man, too, has everywhere the use of fire, and 
by its means can render palatable a variety of animal and 
vegetable substances, which he could hardly otherwise make 
use of, and thus obtains for himself a supply of food far 
more varied and abundant than that which any animal can 
command. 

Thus man, by the mere capacity of clothing himself, and 
making weapons and tools, has taken away from nature that 
power of slowly but permanently changing the external form 
and structure in accordance with changes in the external 
world, which she exercises over all other animals. As the 
competing races by which they are surrounded — the climate, 
the vegetation, or the animals which serve them for food — are 
slowly changing, they must undergo a corresponding change 
in their structure, habits, and constitution to keep them in 
harmony with the new conditions — to enable them to live 
and maintain their numbers. But man does this by means 
of his intellect alone, the variations of which enable him, with 
an unchanged body, still to keep in harmony with the changing 
universe. 

There is one point, however, in which nature will still act 
upon him as it does on animals, and, to some extent, modify 
his external characters. Mr. Darwin has shown that the colour 
of the skin is correlated with constitutional peculiarities both 
in vegetables and animals, so that liability to certain diseases 



176 NATURAL SELECTION vrti 

or freedom froia ttem is often accompanied by marked external 
characters. Now, there is every reason to believe that this 
has acted, and, to some extent, may still continue to act on 
man. In localities where certain diseases are prevalent, those 
individuals of savage races which were subject to them would 
rapidly die off, while those who were constitutionally free 
from the disease would survive, and become the progenitors 
of a new race. These favoured individuals would probably 
be distinguished by peculiarities of colour, with which again 
peculiarities in the texture or the abundance of hair seem to 
be correlated, and thus may have been brought about those 
racial differences of colour which seem to have little relation 
to mere temperature or other obvious peculiarities of climate. 
From the time, therefore, when the social and sympathetic 
feelings came into active operation, and the intellectual and 
moral faculties became fairly developed, man would cease to 
be influenced by natural selection in his physical form and 
structure. As an animal he would remain almost stationary, 
the changes of the surrounding universe ceasing to produce in 
him that powerful modifying effect which they exercise over 
other parts of the organic world. But from the moment that 
the form of his body became stationary, his mind would 
become subject to those very influences from which his body 
had escaped ; every slight variation in his mental and moral 
nature which should enable him better to guard against 
adverse circumstances, and combine for mutual comfort and 
protection, would be preserved and accumulated ; the better 
and higher specimens of our race would therefore increase and 
spread, the lower and more brutal would give way and suc- 
cessively die out, and that rapid advancement of mental 
organisation would occur which has raised the very lowest 
races of man so far above the brutes (although differing so 
little from some of them in physical structure), and, in con- 
junction with scarcely perceptible modifications of form, has 
developed the wonderful intellect of the European races. 

Influence of external Nature in the development of the 
Human Mind 

But from the time when this mental and moral advance 
commenced, and man's physical character became fixed and 



VIII THE DEVELOPMENT OF HUMAN RACES 177 

almost immutaWe, a new series of causes would come into 
action and take part in Ms mental growth. The diverse aspects 
of nature would now make themselves felt, and profoundly 
influence the character of the primitive man. 

When the power that had hitherto modified the body had 
its action transferred to the mind, then races would advance 
and become improved, merely by the harsh discipline of a 
sterile soil and inclement seasons. Under their influence a 
hardier, a more provident, and a more social race would be 
developed than in those regions where the earth produces a 
perennial supply of vegetable food, and where neither fore- 
sight nor ingenuity are required to prepare for the rigours of 
winter. And is it not the fact that in all ages, and in every 
quarter of the globe, the inhabitants of temperate have been 
superior to those of hotter countries ? All the great invasions 
and displacements of races have been from North to South, 
rather than the reverse ; and we have no record of there ever 
having existed, any more than there exists to-day, a solitary 
instance of an indigenous inter-tropical civilisation. The 
Mexican civUisation and government came from the North, 
and, as weU as the Peruvian, was established, not in the rich 
tropical plains, but on the lofty and sterile plateaux of the 
Andes. The religion and civilisation of Ceylon were intro- 
duced from North India ; the successive conquerors of the 
Indian peninsula came from the North-west ; the northern 
Mongols conquered the more Southern Chinese ; and it was 
the bold and adventurous tribes of the North that overran 
and infused new life into Southern Europe. 

Extinction of Lower Eaces 

It is the same great law of " the preservation of favoured 
races in the struggle for life," which leads to the inevitable 
extinction of all those low and mentally undeveloped popula- 
tions with which Europeans come in contact. The red Indian 
in North America and in Brazil ; the Tasmanian, Australian, 
and New Zealander in the southern hemisphere, die out, not 
from any one special cause, but from the inevitable effects 
of an unequal mental and physical struggle. The intellectual 
and moral, as well as the physical, qualities of the European 
are superior ; the same powers and capacities which have 

N 



178 NATURAL SELECTION Vitl 

made him rise in a few centuries from the condition of the 
wandering savage, with a scanty and stationary population, to 
his present state of culture and advancement, with a greater 
average longevity, a greater average strength, and a capacity 
of more rapid increase, — enable him when in contact with the 
savage man to conquer in the struggle for existence, and to 
increase at his expense, just as the better adapted increase at 
the expense of the less adapted varieties in the animal and 
vegetable kingdoms — just as the weeds of Europe overrun 
North America and Australia, extinguishing native produc- 
tions by the inherent vigour of their organisation, and by 
their greater capacity for existence and multiplication. 

The Origin of the Races of Man 

If these views are correct, — if in proportion as man's social, 
moral, and intellectual faculties became developed, his physical 
structure would cease to be aifected by the operation of 
natural selection, — we have a most important clue to the 
origin of races. For it will follow that those great modifica- 
tions of structure and of external form, which resulted in the 
development of man out of some lower type of animal, must 
have occurred before his intellect had raised him above the 
condition of the brutes, at a period when he was gregarious, 
but scarcely social, with a mind perceptive but not reflective, 
ere any sense of right or feelings of sympathy had been 
developed in him. He would be still subject, like the rest of 
the organic world, to the action of natural selection, which 
would retain his physical form and constitution in harmony 
with the surrounding universe. He was probably at a very 
early period a dominant race, spreading widely over the 
warmer regions of the earth as it then existed, and in agree- 
ment with what we see in the case of other dominant species, 
gradually becoming modified in accordance with local con- 
ditions. As he ranged farther from his original home, and 
became exposed to greater extremes of climate, to greater 
changes of food, and had to contend with new enemies, organic 
and inorganic, slight useful variations in his constitution 
would be selected and rendered permanent, and would, on 
the principle of " correlation of growth," be accompanied by 
corresponding external physical changes. Thus might have 



Vili THE DEVELOPMENT OF HUMAN RACES 179 

arisen those striking characteristics and special modifications 
which still distinguish the chief races of mankind. The red, 
black, yellow, or blushing white skin ; the straight, the curly, 
the woolly hair ; the scanty or abundant beard ; the straight 
or oblique eyes ; the various forms of the pelvis, the cranium, 
and other parts of the skeleton. 

But while these changes had been going on, his mental 
development had, from some unknown cause, greatly advanced, 
and had now reached that condition in which it began power- 
fully to influence his whole existence, and would therefore 
become subject to the irresistible action of natural selection. 
This action would quickly give the ascendency to mind : 
speech would probably now be first developed, leading to a 
still further advance of the mental faculties ; and from that 
moment man, as regards the form and structure of most parts 
of his body, would remain almost stationary. The art of 
making weapons, division of labour, anticipation of the future, 
restraint of the appetites, moral, social, and sympathetic feel- 
ings, would now have a preponderating influence on his well- 
being, and would therefore be that part of his nature on 
which natural selection would most powerfully act; and 
we should thus have explained that wonderful persistence of 
mere physical characteristics which is the stumbling-block of 
those who advocate the unity of mankind. 

We are now, therefore, enabled to harmonise the conflict- 
ing views of anthropologists on this subject. Man may have 
been — ^indeed I believe must have been — once a homogeneous 
race ; but it was at a period of which we have as yet dis- 
covered no remains — at a period so remote in his history that 
he had not yet acquired that wonderfully developed brain, 
the organ of the mind, which now, even in his lowest examples, 
raises him far above the highest brutes — at a period when 
he had the form but hardly the nature of man, when he 
neither possessed human speech, nor those sympathetic and 
moral feelings which in a greater or less degree everywhere 
now distinguish the race. Just in proportion as these truly 
human faculties became developed in him would his physical 
features become fixed and permanent, because the latter would 
be of less importance to Hs well-being ; he would be kept in 
harmony with the slowly changing universe around him, by 



180 NATURAL SELECTION viii 

an advance in mind rather than by a change in body. If, 
therefore, we are of opinion that he was not really man till 
these higher faculties were fully developed, we may fairly 
assert that there were many originally distinct races of men ; 
while, if we think that a being closely resembling us in form 
and structure, but with mental faculties scarcely raised above 
the brute, must still be considered to have been human, we 
are fully entitled to maintain the common origin of all man- 
kind. 

The Bearing of these Views on the Antiquity of Man 

These considerations, it will be seen, enable us to place the 
origin of man at a much more remote geological epoch than 
has yet been thought possible. He may even have lived in 
the Miocene or Eocene period, when not a single other 
mammal was identical in form with any existing species. 
For, in the long series of ages during which these primeval 
animals were being slowly changed into the species which now 
inhabit the earth, the power which acted to modify them 
would only affect the mental organisation of man. His brain 
alone would have increased in size and complexity, and his 
cranium have undergone corresponding changes of form, while 
the whole structure of lower animals was being changed. 
This will enable us to understand how the fossil crania of 
Deiiise and Engis agree so closely vnth existing forms, al- 
though they undoubtedly existed in company with large 
mammalia now extinct. The Neanderthal skull may be a 
specimen of one of the lowest races then existing, just as the 
Australians are the lowest of our modern epoch. We have 
no reason to suppose that mind and brain and skull modifica- 
tion could go on quicker than that of the other parts of the 
organisation ; and we must therefore look back very far in 
the past to find man in that early condition in which his 
mind was not sufficiently developed, to remove his body from 
the modifying influence of external conditions and the cumu- 
lative action of natural selection. I believe, therefore, that 
there is no d, priori reason against our finding the remains of 
man or his works in the tertiary deposits. The absence of 
all such remains in the European beds of this age has little 
weight, because, as we go farther back in time, it is natural 



viTi THE DEVELOPMENT OF HUMAN RACES 181 

to suppose that man's distribution over the surface of the 
earth was less universal than at present. 

Besides, Europe was in a great measure submerged during 
the tertiary epoch ; and though its scattered islands may have 
been uninhabited by man, it by no means follows that he did 
not at the same time exist in warm or tropical continents. If 
geologists can point out to us the most extensive land in the 
warmer regions of the earth, which has not been submerged 
since Eocene or Miocene times, it is there that we may expect 
to find some traces of the very early progenitors of man. It 
is there that we may trace back the gradually decreasing 
brain of former races, tiU we come to a time when the body 
also begins materially to differ. Then we shall have reached 
the starting-point of the human family. Before that period 
he had not mind enough to preserve his body from change, 
and would, therefore, have been subject to the same com- 
paratively rapid modifications of form as the other mammalia. 

Thdr Bearing on the Dignity and SupreTTMoy of Man 

If the views I have here endeavoured to sustain have any 
foundation, they give us a new argument for placing man 
apart, as not only the head and culminating point of the grand 
series of organic nature, but as in some degree a new and dis- 
tinct order of being. From those infinitely remote ages, when 
the first rudiments of organic life appeared upon the earth, 
every plant and every animal has been subject to one great 
law of physical change. As the earth has gone through its 
grand cycles of geological, climatal, and organic progress, 
every form of life has been subject to its irresistible action, 
and has been continually but imperceptibly moulded into 
such new shapes as would preserve their harmony with the 
ever-changing universe. No living thing could escape this 
law of its being ; none (except, perhaps, the simplest and most 
rudimentary organisms) could remain unchanged and live, 
amid the universal change around it. 

At length, however, there came into existence a being in 
whom that subtle force we term mivd, became of greater 
importance than his mere bodily structure. Though with a 
naked and unprotected body, this gave him clothing against 
the varying inclemencies of the seasons. Though unable to 



182 NATURAL SELECTION viii 

compete with the deer in swiftness, or with the wild bull in 
strength, this gave him weapons with which to capture or 
overcome both. Though less capable than most other animals 
of living on the herbs and the fruits that unaided nature sup- 
plies, this wonderful faculty taught him to govern and direct 
nature to his own benefit, and make her produce food for him, 
when and where he pleased. From the moment when the 
first skin was used as a covering, when the first rude spear 
was formed to assist in the chase, when fire was first used to 
cook his food, when the first seed was sown or shoot planted, 
a grand revolution was effected in nature — a revolution which 
in all the previous ages of the earth's history had had no 
parallel, for a being had arisen who was no longer necessarily 
subject to change with the changing universe — a being who 
was in some degree superior to nature, inasmuch as he knew 
how to control and regulate her action, and could keep him- 
self in harmony with her, not by a change in body, but by an 
advance of mind. 

Here, then, we see the true grandeur and dignity of man. 
On this view of his special attributes, we may admit that 
even those who claim for him a position as an order, a class, 
or a sub-kingdom by himself, have some show of reason on 
their side. He is, indeed, a being apart, since he is not in- 
fluenced by the great laws which irresistibly modify all other 
organic beings. Nay more : this victory which he has gained 
for himself, gives him a directing influence over other exist- 
ences. Man has not only escaped natural selection him- 
self, but he is actually able to take away some of that power 
from nature which before his appearance she universally 
exercised. We can anticipate the time when the earth will 
produce only cultivated plants and domestic animals ; when 
man's selection shall have supplanted natural selection; 
and when the ocean will be the only domain in which that 
power can be exerted, which for countless cycles of ages has 
ruled supreme over aU the earth. 

Their Bearing on the future Bevelopmeni of Mem 

We now find ourselves enabled to answer those who main- 
tain that if Mr. Darwin's theory of the Origin of Species is 
true, man too must change in form, and become developed 



vm THE DEVELOPMENT OF HUMAN RACES 183 

into some other animal as different from his present self as he 
is from the gorilla or the chimpanzee ; and who speculate on 
what this form is likely to be. But it is evident that such 
will not be the case ; for no change of conditions is con- 
ceivable which will render any important alteration of his 
form and organisation so universally useful and necessary to 
him, as to give those possessing it always the best chance of 
surviving, and thus lead to the development of a new species, 
genus, or higher group of man. On the other hand, we 
know that far greater changes of conditions and of his entire 
environment have been undergone by man than any other 
highly organised animal could survive unchanged, and have 
been met by mental, not corporeal adaptation. The difference 
of habits, of food, clothing, weapons, and enemies between 
savage and civilised man is enormous. Difference in bodily 
form and structure there is practically none, except a slightly 
increased size of brain, corresponding to his higher mental 
development. 

We have every reason to believe, then, that man may 
have existed, and may continue to exist, through a series of 
geological periods which shall see all other forms of animal 
life again and again changed ; while he himself remains un- 
changed, except in the two particulars already specified — the 
head and face, as immediately connected with the organ of 
the mind and as being the medium of expressing the most 
refined emotions of his nature, — and to a slight extent in 
colour, hair, and proportions, so far as they are correlated 
with constitutional resistance to disease. 

Summary 

Briefly to recapitulate the argument; — in two distinct 
ways has man escaped the influence of those laws which have 
produced unceasing change in the animal world. 1. By his 
superior intellect he is enabled to provide himself with cloth- 
ing and weapons, and by cultivating the soil to obtain a con- 
stant supply of congenial food. This renders it unnecessary 
for his body to be modifled in accordance with changing con- 
ditions — to gain a warmer natural covering, to acquire more 
powerful teeth or claws, or to become adapted to obtain and 
digest new kinds of food, as circumstances may require. 2. 



184 NATURAL SELECTION viii 

By his superior sympathetic and moral feelings he becomes 
fitted for the social state ; he ceases to plunder the weak and 
helpless of his tribe ; he shares the game which he has caught 
with less active or less fortunate hunters, or exchanges it for 
weapons which even the weak or the deformed can fashion ; 
he saves the sick and wounded from death ; and thus the 
power which leads to the rigid destruction of all animals who 
cannot in every respect help themselves, is prevented from 
acting on him. 

This power is natural selection ; and, as by no other 
means can it be shown that individual variations can ever 
become accumulated and rendered permanent, so as to form 
well-marked races, it follows that the differences which now 
separate mankind from other animals must have been pro- 
duced before he became possessed of a human intellect or 
human sympathies. This view also renders possible, or even 
requires, the existence of man at a comparatively remote 
geological epoch. For, during the long periods in which other 
animals have been undergoing modification in their whole 
structure, to such an amount as to constitute distinct genera 
and families, man's body will have remained generically, or even 
specifically, the same, while his head and brain alone will have 
undergone modification equal to theirs. We can thus under- 
stand how it is that, judging from the head and brain, Pro- 
fessor Owen places man in a distinct sub-class of mammalia, 
while as regards the bony structure of his body, there is the 
closest anatomical resemblance to the anthropoid apes, " every 
tooth, every bone, strictly homologous — which makes the 
determination of the difference between Homo and Pithems 
the anatomist's difficulty." The present theory fully recog- 
nises and accounts for these facts ; and we may perhaps 
claim as corroborative of its truth that it neither requires us 
to depreciate the intellectual chasm which separates man from 
the apes, nor refuses full recognition of the striking resem- 
blances to them, which exist in other parts of his structure. 

Conclusion 

In concluding this brief sketch of a great subject, I would 
point out its bearing upon the future of the human race. If my 
conclusions are just, it must inevitably follow that the higher 



viii THE DEVELOPMENT OF HUMAN RACES 185 

— the more intellectual and moral — must displace the lower 
and more degraded races ; and the power of " natural selec- 
tion," still acting on his mental organisation, must ever lead 
to the more perfect adaptation of man's higher faculties to 
the conditions of surrounding nature, and to the. exigencies 
of the social state. While his external form will probably 
ever remain unchanged, except in the development of that 
perfect beauty which results from a healthy and well organised 
body, refined and ennobled by the highest intellectual faculties 
and sympathetic emotions, his mental constitution may con- 
tinue to advance and improve, till the world is again inhabited 
by a single nearly homogeneous race, no individual of which 
will be inferior to the noblest specimens of existing humanity. 
Our progress towards such a result is very slow, but it 
still seems to be a progress. We are just now living at an 
abnormal period of the world's history, owing to the marvel- 
lous developments and vast practical results of science having 
been given to societies too low morally and intellectually to 
know how to make the best use of them, and to whom they 
have consequently been curses as well as blessings. Among 
civilised nations at the present day it does not seem possible 
for natural selection to act in any way, so as to secure the 
permanent advancement of morality and intelligence j for it is 
indisputably the mediocre, if not the low, both as regards 
morality and intelligence, who succeed best in life and multiply 
fastest. Yet there is undoubtedly an advance — on the whole 
a steady and a permanent one — both in the influence on public 
opinion of a high morality, and in the general desire for in- 
tellectual elevation ; and as I cannot impute this in any way 
to " survival of the fittest," I am forced to conclude that it 
is due to the inherent progressive power of those glorious 
qualities which raise us so immeasui-ably above our fellow 
animals, and at the same time afford us the surest proof that 
there are other and higher existences than ourselves, from 
whom these qualities may have been derived, and towards 
whom we may be ever tending. 



IX 

THE LIMITS OF NATURAL SELECTION AS APPLIED TO MAN 

Throughout this volume I have endeavoured to show that 
the known laws of variation, multiplication, and heredity, 
resulting in a " struggle for existence " and the " survival of 
the fittest," have probably sufficed to produce all the varieties 
of structure, all the wonderful adaptations, all the beauty of 
form and of colour, that we see in the animal and vegetable 
kingdoms. To the best of my ability I have answered the 
most obvious and the most often repeated objections to this 
theory, and have, I hope, added to its general strength, 
by showing how colour — one of the strongholds of the ad- 
vocates of special creation — may be, in almost all its modifi- 
cations, accounted for by the combined influence of sexual 
selection and the need of protection.^ I have also endeavoured 
to show how the same power which has modified animals has 
acted on man ; and have, I believe, proved that, as soon as 
the human intellect became developed above a certain low 
stage, man's body would cease to be materially afiected by 
natural selection, because the development of his mental 
faculties would render important modifications of its form 
and structure unnecessary. It will, therefore, probably ex- 
cite some surprise among my readers to find that I do not 
consider that all nature can be explained on the principles of 
which I am so ardent an advocate ; and that I am now myself 
going to state objections, and to place limits, to the power of 
natural selection. I believe, however, tbat there are such 

' Since ■writing this in 1870 I have come to the conclusion that sexual 
selection has had little, if any, influence on colour. See chap. v. of " Tropi- 
cal Nature " in this volume, and Oarwimsm, chap, x, 



IX LIMITS OF NATURAL SELECTION IN MAN 187 

limits ; and that just as surely as we can trace the action of 
natural laws in tie development of organic forms, and can 
clearly conceive that fuller knowledge would enable us to 
follow step by step the whole process of that development, so 
surely can we trace the action of some unknown higher law, 
beyond and independent of all those laws of which we have 
any knowledge. We can trace this action more or less dis- 
tinctly in many phenomena, the two most important of which 
are — the origin of sensation or consciousness, and the develop- 
ment of man from the lower animals. I shall first consider 
the latter difficulty as more immediately connected with the 
subjects discussed in this volume. 

WTiat Natural Selection can Not do 

In considering the question of the development of man by 
known natural laws, we must ever bear in mind the first prin- 
ciple of natural selection, no less than of the general theory 
of evolution, that all changes of form or structure, all increase 
in the size of an organ or in its complexity, all greater special- 
isation or physiological division of labour, can only be brought 
about in as much as it is for the good of the being so modi- 
fied. Mr. Darwin himself has taken care to impress upon us 
that natural selection has no power to produce absolute 
perfection, but only relative perfection, — no power to advance 
any being much beyond his fellow beings, but only just so 
much beyond them as to enable it to survive them in the 
struggle for existence. Still less has it any power to produce 
mo(Mfications which are in any degree injurious to its pos- 
sessor, and Mr. Darwin frequently uses the strong expression, 
that a single case of this kind would be fatal to his theory. 
If, therefore, we find in man any characters, which all tie 
evidence we can obtain goes to show would have been actually 
injurious to him on their first appearance, they could not 
possibly have been produced by natural selection. Neither 
could any specially developed organ have been so produced 
if it had been merely useless to bim, or if its use were not 
proportionate to its degree of development. Such cases as 
these would prove that some other law, or some other power, 
than natural selection had been at work. But if, further, 
we could see that these very modifications, though hurtful or 



188 NATURAL SELECTION ix 

useless at the time when they first appeared, became in the 
highest degree useful at a much later period, and are now 
essential to the full moral and intellectual development of 
human nature, we should then infer the action of mind, 
foreseeing the future and preparing for it, just as surely as 
we do, when we see the breeder set himself to work with the 
determination to produce a definite improvement in some culti- 
vated plant or domestic animal. I would further remark that 
this inquiry is as thoroughly scientific and legitimate as that 
into the origin of species itself. It is an attempt to solve 
the inverse problem, to deduce the existence of a new power 
of a definite character, in order to account for facts which, 
according to the theory of natural selection, ought not to 
happen. Such problems are well known to science, and the 
search after their solution has often led to the most brilliant 
results. In the case of man, there are facts of the nature 
above alluded to, and in calling attention to them, and in 
inferring a cause for them, I believe that I am as strictly 
within the bounds of scientific investigation as I have been 
in any other portion of my work. 

The Brain of the Savage shovm to he Larger tJum he Needs it to he 

Size of Brain an important Blement of Mental Power. — The 
brain is universally admitted to be the organ of the mind ; 
and it is almost as universally admitted that size of brain is 
one of the most important of the elements which determine 
mental power or capacity. There seems to be no doubt that 
brains differ considerably in quality, as indicated by greater 
or less complexity of the convolutions, quantity of gray 
matter, and perhaps unknown peculiarities of organisation; 
but this difference of quality seems merely to increase or 
diminish the influence of quantity, not to neutralise it. 
Thus, all the most eminent modern writers see an intimate 
connection between the diminished size of the brain in the 
lower races of mankind, and their intellectual inferiority. 
The collections of Dr. J. B. Davis and Dr. Morton give the 
following as the average internal capacity of the cranium in 
the chief races : Teutonic family, 94 cubic inches ; Esquimaux, 
91 cubic inches; Negroes, 85 cubic inches; Australians and Tas- 
manians, 82 cubic inches; Bushmen, 77 cubic inches. These 



IX LIMITS OF NATURAL SELECTION IN MAN 189 

last numbers, however, are deduced from comparatively few speci- 
mens, and may be below the average, just as a small number of 
Finns and Cossacks give 98 cubic inches, or considerably more 
than that of the German races. It is evident, therefore, that the 
absolute bulk of the brain is not necessarily much less in savage 
than in civilised man, for Esquimaux skulls are known with a 
capacity of 11 3 inches, or hardly less than the largest among 
Europeans. But what is stiU more extraordinary, the few 
remains yet known of prehistoric man do not indicate any 
material diminution in the size of the brain case. A Swiss 
skull of the stone age, found iu the lake dwelling of MeUen, 
corresponded exactly to that of a Swiss youth of the present 
day. The celebrated Neanderthal skuU had a larger circum- 
ference than the average, and its capacity, indicating actual 
mass of brain, is estimated to have been not less than 75 
cubic inches, or nearly the average of existing Australian 
crania. The Engis skull, perhaps the oldest known, and 
which, according to Sir John Lubbock, " there seems no doubt 
was reaUy contemporary with the mammoth and the cave 
bear," is yet, according to Professor Huxley, " a fair average 
skull, which might have belonged to a philosopher, or might 
have contained the thoughtless brains of a savage." Of the 
cave men of Les Eyzies, who were undoubtedly contemporary 
with the reindeer in the south of France, Professor Paul 
Broca says (ia a paper read before the Congress of Pre- 
historic Archaeology in 1868): "The great capacity of the 
brain, the development of the frontal region, the fine elliptical 
form of the anterior part of the profile of the skull, are incon- 
testible characteristics of superiority, such as we are accus- 
tomed to meet with in civilised races ; " yet the great breadth 
of the face, the enormous development of the ascending ramus 
of the lower jaw, the extent and roughness of the surfaces for 
the attachment of the muscles, especially of the masticators, 
and the extraordinary development of the ridge of the femur, 
indicate great muscular power, and the habits of a savage and 
brutal race. 

These facts might almost make us doubt whether the size 
of the brain is in any direct way an index of mental power, 
had we not the most conclusive evidence that it is so, in the 
fact that, whenever an adult male European has a skull less 



190 NATURAL SELECTION ix 

than 19 inclies in circumference, or has less than 65 cubic inches 
of brain, he is invariably idiotic. When we join with this the 
equally undisputed fact that great men, — those who combine 
acute perception with great reflective power, strong passions, 
and general energy of character, such as Napoleon, Ouvier, and 
O'Connell, — have always heads far above the average size, we 
must feel satisfied that volume of brain is one, and perhaps the 
most important, measure of intellect ; and this being the case, 
we cannot fail to be struck with the apparent anomaly that 
many of the lowest savages should have as much brains as 
average Europeans. The idea is suggested of a surplusage of 
power — of an instrument beyond the needs of its possessor. 

Gompa/rison of the Brains of Man and of Anthropoid Apes. — 
In order to discover if there is any foundation for this notion, 
let us compare the brain of man with that of animals. The 
adult male orang-utan is quite as bulky as a small sized man, 
while the gorilla is considerably above the average size of 
man, as estimated by bulk and weight ; yet the former has a 
brain of only 28 cubic inches, the latter, one of 30, or, in the 
largest specimen yet known, of 34^ cubic inches. We have 
seen that the average cranial capacity of the lowest savages is 
probably not less than five-sixths of that of the highest civilised 
races, while the brain of the anthropoid apes scarcely amounts 
to one-third of that of man, in both cases taking the average ; 
or the proportions may be more clearly represented by the 
following figures : Anthropoid apes, 1 ; savages, 26; civilised 
man, 32. But do these figures at all approximately represent 
the relative intellect of the three groups ? Is the savage really 
no further removed from the philosopher, and so much removed 
from the ape, as these figures would indicate 1 In considering 
this question, we must not forget that the heads of savages vary 
in size almost as much as those of civilised Europeans. Thus, 
while the largest Teutonic skull in Dr. Davis's collection is 11 2 -4 
cubic inches, there is an Araucanian of 11 5 -5, an Esquimaux of 
113-1, a Marquesan of 110-6, a Negro of 105-8, and even an 
Australian of 104-5 cubic inches. We may, therefore, fairly 
compare the savage with the highest European on the one side, 
and with the orang, chimpanzee, or gorilla, on the other, 
and see whether there is any relative proportion between 
brain and intellect 



tie LIMITS OP NATURAL SELECTION IN MAN 191 

Range of Intellectual Power in Man. — First, let us consider 
what this wonderful instrument, the hrain, is capable of in 
its higher developments. In Mr. Galton's interesting work 
on Hereditary Genius, he remarks on the enormous differ- 
ence between the intellectual power and grasp of the well- 
trained mathematician or man of science, and the average 
Englishman. The number of marks obtained by high 
wranglers is often more than thirty times as great as that 
of the men at the bottom of the honour list, who are still 
of fair mathematical ability ; and it is the opinion of skilled 
examiners that even this does not represent the full difference 
of intellectual power. If, now, we descend to those savage 
tribes who only count to three or five, and who find it im- 
possible to comprehend the addition of two and three without 
having the objects actually before them, we feel that the 
chasm between them and the good mathematician is so vast 
that a thousand to one will probably not fully express it. 
Yet we know that ' the mass of brain might be nearly the 
same in both, or might not differ in a greater proportion than 
as 5 to 6 ; whence we may fairly infer that the savage pos- 
sesses a brain capable, if cultivated and developed, of per- 
forming work of a kind and degree far beyond what he ever 
requires it to do. 

Again, let us consider the power of the higher or even the 
average civilised man, of forming abstract ideas, and carrying 
on more or less complex trains of reasoning. Our languages 
are full of terms to express abstract conceptions. Our busi- 
ness and our pleasures involve the continual foresight of many 
contingencies. Our law, our government, and our science 
continually require us to reason through a variety of compli- 
cated phenomena to the expected result. Even our games, 
such as chess, compel us to exercise all these faculties in a 
remarkable degree. Compare this with the savage languages, 
which contain no words for abstract conceptions ; the utter 
want of foresight of the savage man beyond his simplest 
necessities j his inability to combine, or to compare, or to 
reason on any general subject that does not immediately 
appeal to his senses. So, in his moral and aesthetic faculties, 
the savage has none of those wide sympathies with all nature, 
those conceptions of the infinite, of the good, of the sublime 



192 NATURAL SELECTION ix 

and beautiful, -wliich are so largely developed in civilised 
man. Any considerable development of these would, in fact, 
be useless or even hurtful to him, since they would to some 
extent interfere with the supremacy of those perceptive and 
apimal faculties on which his very existence often depends, in 
the severe struggle he has to carry on against nature and his 
fellow-man. Yet the rudiments of all these powers and feel- 
ings undoubtedly exist in him, since one or other of them 
frequently manifest themselves in exceptional cases, or when 
some special circumstances call them forth. Some tribes, 
such as the Santals, are remarkable for as pure a love of 
truth as the most moral among civilised men. The Hindoo 
and the Polynesian have a high artistic feeling, the first traces 
of which are clearly visible in the rude drawings of the 
palaeolithic men who were the contemporaries in France of 
the reindeer and the mammoth. Instances of unselfish love, 
of true gratitude, and of deep religious feeling, sometimes 
occur among most savage races. 

On the whole, then, we may conclude that the general, 
moral, and intellectual development of the savage is not less 
removed from that of civilised man than has been shown to 
be the case in the one department of mathematics ; and from 
the fact that all the moral and intellectual faculties do occa- 
sionally manifest themselves, we may fairly conclude that they 
are always latent, and that the large brain of the savage man 
is much beyond his actual requirements in the savage state. 

Intellect of Savages and of Anvmals cmrvpa/red. — Let us 
now compare the intellectual wants of the savage, and the 
actual amount of intellect he exhibits, with those of the 
higher animals. Such races as the Andaman Islanders,, 
the Australians, and the Tasmanians, the Digger Indians of 
North America, or the natives of Fuegia, pass their lives so 
as to require the exercise of few faculties not possessed in an 
equal degree by many animals. In the mode of capture of 
game or fish they by no means surpass the ingenuity or fore- 
thought of the jaguar, who drops saliva into the water, and 
seizes the fish as they come to eat it ; or of wolves and 
jackals, who hunt in packs; or of the fox, who buries his 
surplus food till he requires it. The sentinels placed by 
antelopes and by monkeys, and the various modes of building 



IX LIMITS OF NATURAL SELECTION IN MAN 193 

adopted by field mice and beavers, as well as the sleeping- 
place of the orang-utan, and the tree-shelter of some of the 
African anthropoid apes, may well be compared with the 
amount of care and forethought bestowed by many savages 
in similar circumstances. His possession of free and perfect 
hands, not required for locomotion, enables man to form and 
use weapons and implements which are beyond the physical 
powers of brutes ; but having done this, he certainly does not 
exhibit more mind in using them than do many lower animals. 
What is there in the life of the savage but the satisfying of 
the cravings of appetite in the simplest and easiest way? 
What thoughts, ideas, or actions are there that raise him 
many grades above the elephant or the ape ? Yet he pos- 
sesses, as we have seen, a brain vastly superior to theirs in 
size and complexity ; and this brain gives him, in an unde- 
veloped state, faculties which he never requires to use. And 
if this is true of existing savages, how much more true must 
it have been of the men whose sole weapons were rudely 
chipped flints, and some of whom, we may fairly conclude, 
were lower than any existing race ; while the only evidence 
yet in our possession shows them to have had brains fully 
as capacious as those of the average of the lower savage 
races. 

We see, then, that whether we compare the savage with 
the higher developments of man, or with the brutes around 
him, we are alike driven to the conclusion that in his large and 
well-developed brain he possesses an organ quite dispropor- 
tionate to his actual requirements — an organ that seems pre- 
pared in advance, only to be fully utilised as he progresses in 
civilisation. A brain one-half larger than that of the gorilla 
would, according to the evidence before us, fully have sufficed 
for the limited mental development of the savage ; and we 
must therefore admit that the large brain he actually pos- 
sesses could never have been solely developed by any of those 
laws of evolution, whose essence is, that they lead to a degree 
of organisation exactly proportionate to the wants of each 
species, never beyond those wants — ^that no preparation can 
be made for the future development of the race — that one 
part of the body can never increase in size or complexity, ex- 
cept in strict co-ordination to the pressing wants of the whole. 





194 NATURAL SELECTION ix 

The brain of preHstoric and of savage man seems to me to 
prove the existence of some power distinct from that which 
has guided the development of the lower animals through 
their ever-varying forms of being. 

The Use of the Hairy Covering of Mammalia 

Let us now consider another point in man's organisation, 
the bearing of which has been almost entirely overlooked by 
writers on both sides of this question. One of the most 
general external characters of the terrestrial mammalia is 
the hairy covering of the body, which, whenever the skin is 
flexible, soft, and sensitive, forms a natural protection against 
the severities of climate, and particularly against rain. That 
this is its most important function is well shown by the 
manner in which the hairs are disposed so as to carry ofif the 
water, by being invariably directed downwards from the most 
elevated parts of the body. Thus, on the under surface the 
hair is always less plentiful, and, in many cases, the belly is 
almost bare. The hair lies downwards, on the limbs of all 
walking mammals, from the shoulder to the toes ; but in the 
orang-utan it is directed from the shoulder to the elbow, and 
again from the wrist to the elbow, in a reverse direction. 
This corresponds to the habits of the animal, which, when 
resting, holds its long arms upwards over its head, or clasping 
a branch above it, so that the rain would flow down both the 
arm and forearm to the long hair which meets at the elbow. 
In accordance with this principle, the hair is always longer 
or more dense along the spine or middle of the back 
from the nape to the tail, often rising into a crest of hair 
or bristles on the ridge of the back. This character prevails 
through the entire series of the mammalia, from the mar- 
supials to the quadrumana, and by this long persistence it 
must have acquired such a powerful hereditary tendency 
that we should expect it to reappear continually even 
after it had been abolished by ages of the most rigid 
selection; and we may feel sure that it never could have 
been completely abolished under the law of natural selec- 
tion, unless it had become so positively injurious as to 
lead to the almost invariable extinction of individuals 
possessing it. 



LIMITS OF NATURAL SELECTION IN MAN 195 



The constant Absence of Hair from certain pa/rts of Man's 
Body a remarkable Phenomenon 

In man the hairy covering of the body has almost totally 
disappeared, and, what is very remarkable, it has disappeared 
more completely from the back than from any other part of 
the body. Bearded and beardless races alike have the back 
smooth, and even when a considerable quantity of hair 
appears on the limbs and breast, the back, and especially the 
spinal region, is absolutely free, thus completely reversing 
the characteristics of all other mammaKa. The Ainos of the 
KurUe Islands and Japan are said to be a hairy race ; but 
Mr. Bickmore, who saw some of them, and described them in 
a paper read before the Ethnological Society, gives no details 
as to where the hair was most abundant, merely stating gene- 
rally that "their chief peculiarity is their great abundance 
of hair, not only on the head and face, but over the whole 
body." This might very well be said of any man who had 
hairy limbs and breast, unless it was specially stated that his 
back was hairy, which is not done in this case. The hairy 
family in Birmah have, indeed, hair on the back rather longer 
than on the breast, thus reproducing the true mammalian 
character, but they have still longer hair on the face, fore- 
head, and inside the ears, which is quite abnormal ; and the 
fact that their teeth are all very imperfect shows that this is 
a case of monstrosity rather than one of true reversion to the 
ancestral type of man before he lost his hairy covering. 

Savage Man feels the Want of this Hairy Covering 
We must now inquire if we have any evidence to show, 
or any reason to believe, that a hairy covering to the back 
would be in any degree hurtful to savage man, or to man in 
any stage of his progress from his lower animal form ; and 
if it were merely useless, could it have been so entirely 
and completely removed as not to be continually reappearing 
in mixed races ? Let us look to savage man for some light 
on these points. One of the most common habits of savages 
is to use some covering for the back and shoulders, even when 
they have none on any other part of the body. The early 
voyagers observed with surprise that the Tasmanians, both 



196 NATURAL SELECTION ix 

men and women, wore the kangaroo- skin, which was their 
only covering, not from any feeling of modesty, but over the 
shoulders to keep the back dry and warm. A cloth over the 
shoulders was also the national dress of the Maories. The 
Patagonians wear a cloak or mantle over the shoulders, and 
the Fuegians often wear a small piece of skin on the back, 
laced on, and shifted from side to side as the wind blows. 
The Hottentots also wore a somevhat similar skin over the 
back, which they never removed, and in which they were 
buried. Even in the tropics most savages take precautions 
to keep their backs dry. The natives of Timor use the leaf 
of a fan palm, carefully stitched up and folded, which they 
always carry with them, and which, held over the back, forms 
an admirable protection from the rain. Almost all the Malay 
races, as well as the Indians of South America, make great 
palm-leaf hats, four feet of more across, which they use during 
their canoe voyages to protect their bodies from heavy showers 
of rain ; and they use smaller hats of the same kind when 
travelling by land. 

"We iind, then, that so far from there being any reason to 
believe that a hairy covering to the back could have been 
hurtful or even useless to prehistoric man, the habits of 
modern savages indicate exactly the opposite view, as they 
evidently feel the want of it, and are obliged to provide 
substitutes of various kinds. The perfectly erect posture of 
man may be supposed to have something to do with the dis- 
appearance of the hair from his body while it remains on his 
head ; but when walking, exposed to rain and wind, a man 
naturally stoops forwards and thus exposes his back ; and the 
undoubted fact that most savages feel the effects of cold and 
wet most severely in that part of the body, sufficiently demon- 
strates that the hair could not have ceased to grow there merely 
because it was useless, even if it were likely that a character 
so long persistent in the entire order of mammalia could have 
so completely disappeared under the influence of so weak a 
selective power as a diminished usefulness. 

Mom's Naked Skin could not have been produced by Natural Selection 

It seems to me, then, to be absolutely certain that natural 

selection could not have produced man's hairless body by 



IX LIMITS OF NATURAL SELECTION IN MAN 197 

the accumulation of variations from a hairy ancestor. The 
evidence all goes to show that such variations could not have 
been useful, but must, on the contrary, have been to some 
extent hurtful. If even, owing to an unknown correlation 
with other hurtful qualities, it had been abolished in the 
ancestral tropical man, we cannot conceive that, as man 
spread into colder climates, it should not have returned under 
the powerful influence of reversion to such a long persistent 
ancestral type. But the very foundation of such a supposi- 
tion as this is untenable, for we cannot suppose that a 
character which, like hairiness, exists throughout the whole 
of the mammalia, can have become, in one form only, so 
constantly correlated with an injurious character as to lead to 
its permanent suppression — a suppression so complete and 
effectual that it never, or scarcely ever, reappears in mongrels 
of the most widely different races of man. 

Two characters could hardly be wider apart than the size 
and development of man's brain and the distribution of hair 
upon the surface of his body, yet they both lead us to the 
same conclusion — that some other power than natural selec- 
tion has been engaged in his production. 

Feet and Hands of Man, considered as Difficulties on 
the Themy of Natwal Selection 
There are a few other physical characteristics of man that 
may just be mentioned as offering similar difficulties, though 
I do not attach the same importance to them as to those I 
have already dwelt on. The specialisation and perfection of 
the hands and feet of man seems difficult to account for. 
Throughout the whole of the quadrumana the foot is pre- 
hensile, and a very rigid selection must therefore have been 
needed to bring about that arrangement of the bones and 
muscles which has converted the thumb into a great toe, so 
completely, that the power of opposabiUty is totally lost in 
every race, whatever some travellers may vaguely assert to 
the contrary. It is difficult to see why the prehensile power 
should have been taken away. It must certainly have been 
useful in climbing, and the case of the baboons shows that it 
is quite compatible with terrestrial locomotion. It may not 
be compatible with perfectly easy erect locomotion ; but, then, 



NATURAL SELECTION 



how can we conceive that early man, as an animal, gained 
anything by purely erect locomotion? Again, the hand of 
man contains latent capacities and powers which are unused 
by savages, and must have been even less used by palaeolithic 
man and his still ruder predecessors. It has all the appear- 
ance of an organ prepared for the use of civilised man, and 
one which was required to render civilisation possible. Apes 
make little use of their separate fingers and opposable thumbs. 
They grasp objects rudely and clumsily, and look as if a much 
less specialised extremity would have served their piu'pose as 
well. I do not lay much stress on this, but, if it be proved 
that some intelligent power has guided or determined the 
development of man, then we may see indications of that 
power in facts which, by themselves, would not serve to 
prove its existence. — 

The Voice of Man. — The same remark will apply to another 
peculiarly human character, the wonderful power, range, 
flexibility, and sweetness of the musical sounds producible 
by the human larynx, especially in the female sex. The 
habits of savages give no indication of how this faculty could 
have been developed by natural selection, because it is never 
required or used by them. The singing of savages is a more 
or less monotonous howling, and the females seldom sing at 
all. Savages certainly never choose their wives for fine voices, 
but for rude health, and strength, and physical beauty. 
Sexual selection could not therefore have developed this 
wonderful power, which only comes into play among civilised 
people. It seems as if the organ had been prepared in anti- 
cipation of the future progress of man, since it contains latent 
capacities which are useless to him in his earlier condition. 
The delicate correlations of structure that give it such mar- 
vellous powers could not therefore have been acquired by 
means of natural selection. 

The Origin of some of Man's Mental Faculties, hy the pre- 
servation of Useful Variations, not possiUe 

Turning to the mind of man, we meet with many difficulties 
in attempting to understand how those mental faculties, 
which are especially human, could have been acquired by the 
preservation of useful variations. At first sight, it would 



IX LIMITS OF NATURAL SELECTION IN MAN 199 

seem that such feelings as those of abstract justice and bene- 
volence could never have been so acquired, because they are 
incompatible with the law of the strongest, which is the 
essence of natural selection. But this is, I think, an errone- 
ous view, because we must look, not to individuals, but to 
societies ; and justice and benevolence exercised towards mem- 
bers of the same tribe would certainly tend to strengthen 
that tribe and give it a superiority over another in which the 
right of the strongest prevailed, and where, consequently, the 
weak and the sickly were left to perish, and the few strong 
ruthlessly destroyed the many who were weaker. 

But there is another class of human faculties that do not 
regard our fellow-men, and which cannot, therefore, be thus 
accounted for. Such are the capacity to form ideal concep- 
tions of space and time, of eternity and iafinity — the capacity 
for intense artistic feelings of pleasure, in form, colour, and 
composition, and for those abstract notions of form and 
number which render geometry and arithmetic possible. 
How were all or any of these faculties first developed, when 
they could have been of no possible use to man in his 
early stages of barbarism ? How could natural selection, or 
survival of the fittest in the struggle for existence, at all 
favour the development of mental powers so entirely removed 
from the material necessities of savage men, and which even 
now, with our comparatively high civilisation, are, in their 
farthest developments, in advance of the age, and appear to 
have relation rather to the future of the race than to its 
actual status ? ^ 

Difficulty as to the Origin of the Moral Sense 
Exactly the same difficulty arises when we endeavour to 
account for the development of the moral sense or conscience 
in savage man; for although the p-actice of benevolence, 
honesty, or truth may have been useful to the tribe possess- 
ing these virtues, that does not at all account for the peculiar 
sanctity attached to actions which each tribe considers right 
and moral, as contrasted with the very different feelings with 
which they regard what is merely useful. The utUitaiian 

1 This argument is extended and some new illustrations given in Darwin- 
ism, pp. 461-471 



200 NATURAL SELECTION ix 

hypothesis (which is the theory of natural selection applied to 
the mind) seems inadequate to account for the development 
of the moral sense. This subject has been recently much 
discussed, and I will here only give one example to illustrate 
my argument. The utilitarian sanction for truthfulness is by 
no means very powerful or universal. Few laws enforce it. 
No very severe reprobation follows untruthfulness. In all 
ages and countries falsehood has been thought allowable in 
love, and laudable in war ; while, at the present day, it is 
held to be venial by the majority of mankind in trade, com- 
merce, and speculation. A certain amount of untruthfulness 
is a necessary part of politeness in the East and West alike, 
while even severe moralists have held a lie justifiable to elude 
an enemy or prevent a crime. Such being the difficulties with 
which this virtue has had to struggle, with so many excep- 
tions to its practice, with so many instances in which it 
brought ruin or death to its too ardent devotee, how can we 
believe that considerations of utility could ever invest it with 
the mysterious sanctity of the highest virtue, — could ever 
induce men to value truth for its own sake, and practise it 
regardless of consequences ? 

Yet it is a fact that such a mystical sense of wrong does 
attach to untruthfulness, not only among the higher classes of 
civilised people, but among whole tribes of utter savages. 
Sir Walter Elliott tells us (in his paper " On the Character- 
istics of the Population of Central and Southern India," 
published in the Journal of the Ethnological Society of 
London, vol. i. p. 107) that the Kurubars and Santals, , 
barbarous hill-tribes of Central India, are noted for veracity. 
It is a common saying that "a Kurubar always speaks the 
truth ; " and Major Jervis says, " the Santals are the most 
truthful men I ever met with." As a remarkable instance 
of this quality the following fact is given. A number of 
prisoners, taken dming the Santal insurrection, were allowed 
to go free on parole, to work at a certain spot for wages. 
After some time cholera attacked them and they were obliged 
to leave, but every man of them returned and gave up his 
earnings to the guard. Two hundred savages, with money in 
their girdles, walked thirty miles back to prison rather than 
break their word ! My own experience among savages has 



IX LIMITS OF NATURAL SELECTION IN MAN 201 

furnished me with similar, although lest severely tested, 
instances ; and we cannot avoid asking. How is it that in 
these few cases "experiences of utility" have left such an 
overwhelming impression, while in so many others they have 
left none ? The experiences of savage men as regards the 
utility of truth must, in the long run, be pretty nearly equal. 
How is it, then, that in some cases the resiilt is a sanctity 
which overrides all considerations of personal advantage, while 
in others there is hardly a rudiment of such a feeling ? 

The intuitional theory, which I am now advocating, ex- 
plains this by the supposition that there is a feeling — a sense 
of right and wrong — in our nature, antecedent to and inde- 
pendent of experiences of utUity. Where free play is 
allowed to the relations between man and man, this feeling 
attaches itself to those acts of universal utility or self- 
sacrifice which are the products of oiu" afiections and sym- 
pathies, and which we term moral ; while it may be, and 
often is, perverted, to give the same sanction to acts of narrow 
and conventional utility which are really immoral, — as when 
the Hindoo will tell a lie, but will sooner starve than eat 
unclean food, and looks upon the marriage of adult females 
as gross immorality. 

The strength of the moral feeling will depend upon 
individual or racial constitution, and on education and 
habit ; — the acts to which its sanctions are applied will 
depend upon how far the simple feelings and aifections of 
our nature have been modified by custom, by law, or by 
religion. 

It is difficult to conceive that such an intense and mystical 
feeHng of right and wrong (so intense as to overcome all ideas 
of personal advantage or utility), could have been developed 
out of accumulated ancestral experiences of utility; and 
still more difficult to understand how feelings developed by 
one set of utilities could be transferred to acts of which the 
utility was partial, imaginary, or altogether absent. But if a 
moral sense is an essential part of our nature, it is easy to 
see that its sanction may often be given to acts which are 
useless or immoral; just as the natural appetite for drink 
is perverted by the drunkard into the means of his de- 
struction. 



202 NATURAL SELECTION . ix 

Summary of the Argument as to the Insufficiency of Natural 
Selection to accownt for the Development of Man 

Briefly to resume my argument — ^I have shown that the 
brain of the lowest savages, and, as far as we yet know, of 
the prehistoric races, is little inferior in size to that of the 
highest types of man, and immensely superior to that of the 
higher animals ; while it is universally admitted that quantity 
of brain is one of the most important, and probably the most 
essential, of the elements which determine mental power. 
Yet the mental requirements of savages, and the faculties 
actually exercised by them, are very little above those of 
animals. The higher feelings of .pure morality and refined 
emotion, and the power of abstract reasoning and ideal con- 
ception, are useless to them, are rarely if ever manifested, and 
have no important relations to their habits, wants, desires, 
or well-being. They possess a mental organ beyond their 
needs. Natural selection ^pvdd only have endowed savage 
man with a brain a-JajtdfigE&s- superior to that of an ape, 
whereas he actually possesses one very Kttle inferior to that 
of a philosopher. 

The soft, naked, sensitive skin of man, entirely free from 
that hairy covering which is so imiversal among other mam- 
malia, cannot be explained on the theory of natural selection. 
The habits of savages show that they feel the want of this 
covering, which is most completely absent in man exactly 
where it is thickest in other animals. We have no reason 
whatever to believe that it could have been hurtful or even 
useless to primitive man ; and, under these circumstances, its 
complete abolition, shown by its never reverting in mixed 
breeds, is a demonstration of the agency of some other power 
than the law of the survival of the fittest, in the development 
of man from the lower animals. 

Other characters show difficulties of a similar kind, though 
not perhaps in an equal degree. The structure of the human 
foot and hand seem unnecessarily perfect for the needs of 
savage man, in whom they are as completely and as humanly 
developed as in the highest races. The structure of the 
human larynx, giving the power of speech and of producing 
musical sounds, and especially its extreme development in 



IX LIMITS OF NATURAL SELECTION IN MAN 203 

the female sex, are shown to be beyond the needs of 
savages, and, from their known habits, impossible to have 
been acquired either by sexual selection or by survival of 
the fittest. 

The mind of man offers arguments in the same direction, 
hardly less strong than those derived from his bodily struc- 
ture. A number of his mental faculties have no relation to 
his fellow-men, or to his material progress. The power of 
conceiving eternity and infinity, and aU those purely abstract 
notions of form, number, and harmony, which play so large 
a part in the life of civilised races, are entirely outside of 
the world of thought of the savage, and have no influence 
on his individual existence or on that of his tribe. They 
could not, therefore, have been developed by any preserva- 
tion of useful forms of thought ; yet we find occasional 
traces of them amidst a low civilisation, and at a time when 
they could have had no practical efiect on the success of the 
individual, the family, or the race ; and the development of 
a moral sense or conscience by similar means is equally 
inconceivable. 

But, on the other hand, we find that every one of these 
characteristics is necessary for the full development of human 
nature. The rapid progress of civilisation under favourable 
conditions would not be possible, were not the organ of the 
mind of man prepared in advance, fully developed as regards 
size, structure, and proportions, and only needing a few 
generations of use and habit to co-ordinate its complex func- 
tions. The naked and sensitive sMn, by necessitating clothing 
and houses, would lead to the more rapid development of 
man's inventive and constructive faculties ; and, by leading 
to a more refined feeling of personal modesty, may have 
influenced, to a considerable extent, his moral nature. The 
erect form of man, by freeing the hands from all locomotive 
uses, has been necessary for his intellectual advancement ; 
and the extreme perfection of his hands has alone rendered 
possible that excellence in all the arts of civilisation which 
raises him so far above the savage, and is perhaps but the 
forerunner of a higher intellectual and moral advancement. 
The perfection of his vocal organs has flrst led to the forma- 
tion of articulate speech, and then to the development of 



Wi NATUKAL SELECTION ix 

those exquisitely toned sounds, wMch are only appreciated 
by the higher races, and which are probably destined for 
more elevated uses and more refined enjoyment in a higher 
condition than we have yet attained to. So, those faculties 
which enable us to transcend time and space, and to realise 
the wonderful conceptions of mathematics and philosophy, or 
which give us an intense yearning for abstract truth (aU of 
which were occasionally manifested at such an early period 
of human history as to be far in advance of any of the few 
practical applications which have since grown out of them), 
are evidently essential to the perfect development of man as 
a spiritual being, but are utterly inconceivable as having been 
produced through the action of a law which looks only, and 
can look only, to the immediate material welfare of the indi- 
vidual or the race. 

The inference I would draw from this class of phenomena 
is, that a superior intelligence has guided the development 
of man in a definite direction, and for a special purpose, just 
as man guides the development of many animal and vegetable 
forms. The laws of evolution alone would, perhaps, never 
have produced a grain so well adapted to man's use as wheat 
and maize ; such fruits as the seedless banana and bread- 
fruit ; or such animals as the Guernsey milch cow, or the 
London dray-horse. Yet these so closely resemble the un- 
aided productions of nature, that we may well imagine a 
being who had mastered the laws of development of organic 
forms through past ages, refusing to believe that any new 
power had been concerned in their production, and scornfully 
rejecting the theory (as my theory will be rejected by 
many who agree with me on other points) that in these few 
cases a controlling intelligence had directed the action of the 
laws of variation, multiplication, and survival, for his own 
purposes. We know, however, that this has been done ; and 
we must therefore admit the possibility that, if we are not 
the highest intelligences in the universe, some higher intelli- 
gence may have directed the process by which the human 
race was developed, by means of more subtle agencies than 
we are acquainted with. At the same time I must confess 
that this theory has the disadvantage of requiring the inter- 
vention of some distinct individual intelligence, to aid in the 



IX LIMITS OF NATURAL SELECTION IN MAN 205 

production of what we can hardly avoid considering as the 
ultimate aim and outcome of all organised existence — intel- 
lectual, ever-advancing, spiritual man. It therefore implies 
that the great laws which govern the material universe were 
insufficient for his production, unless we consider (as we may 
fairly do) that the controlling action of such higher intelli- 
gences is a necessary part of those laws, just as the action of 
all sittrounding organisms is one of the agencies in organic 
development. But even if my particular view should not be 
the true one, the difficulties I have put forward remain, and, 
I think, prove that some more general and more funda- 
mental law underlies that of natiu-al selection. The law of 
" unconscious intelligence " pervading all organic nature, put 
forth by Dr. Laycock and adopted by Mr. Murphy, is such 
a law ; ' but to my mind it has the double disadvantage of 
being both unintelligible and incapable of any kind of proof. 
It is more probable that the true law lies too deep for us to 
discover it ; but there seems to me to be ample indications 
that such a law does exist, and is probably connected with the 
absolute origin of life and organisation.^ 

1 Some of my critics seem quite to have misunderstood my meaning in this 
part of the argument. They have accused me of unnecessarily and unphiloso- 
phically appealing to "first causes" in order to get over a diflSculty — of 
believing that " our brains are made by God and our lungs by natural selec- 
tion;" and that, in point of fact, "man is God's domestic animal." An 
eminent French critic, M. ClapaxMe, makes me continually call in the aid of 
— " une Force supSrieure," the capital P meaning, I imagine, that this 
" higher Force " is the Deity. I can only explain this misconception by the 
incapacity of the modem cultivated mind to realise the existence of any 
higher intelligence between itself and Deity. Angels and archangels, spirits 
and demons, have been so long banished from our belief as to have become 
actually untiinkable as actual existences, and nothing in modem philosophy 
takes their place. Yet the grand law of " continuity," the last outcome of 
modern science, which seems absolute throughout the realms of matter, force, 
and mind, so far as we can explore them, cannot surely fail to be true beyond 
the narrow sphere of our vision, and leave an infinite chasm between man 
and the Great Mind of the universe. Such a supposition seems to me in 
the highest degree improbable. 

Now, in referring to the origin of man, and its possible determining 
causes, I have used the words "some other power" — "some intelligent 
power" — " a superior intelligence " — "a controlling intelligence," and only 
in reference to the origin of universal forces and laws have I spoken of the 
will or power of " one Supreme Intelligence." These are the only expres- 
sions I have used in alluding to the power which I believe has acted in the 
case of man, and they were purposely chosen to show that I reject the 
hypothesis of " first causes " for any and every fecial eSeat in the universe, 



206 NATURAL SELECTION 



The Origin of Consciousness 

The question of the origin of sensation and of thought 
can be but briefly discussed in this pkce, since it is a subject 
-wi&B enough to require a separate volume for its proper 
treatment. No physiologist or philosopher has yet ventured 
to propound an intelligible theory of how sensation may 
possibly be a product of organisation ; while many have 
declared the passage from matter to mind to be inconceiv- 
able. In his presidental address to the Physical Section of 
the British Association at Norwich, in 1868, Professor Tyndall 
expressed himself as follows : — 

" The passage from the physics of the brain to the corre- 
sponding facts of consciousness is unthinkable. Granted that 
a definite thought and a definite molecular action in the brain 
occur simultaneously, we do not possess the intellectual organ, 
nor apparently any rudiment of the organ, which would 
enable us to pass by a process of reasoning from the one 
phenomenon to the other. They appear together, but we do 
not know why. Were our minds and senses so expanded, 
strengthened, and illuminated as to enable us to see and feel 
the very molecules of the brain, — were we capable of following 
all their motions, all their groupings, all their electric dis- 
charges, if such there be, and were we intimately acquainted 
with the corresponding states of thought and feeling, — we 
should be as far as ever from the solution of the problem, 
' How are these physical processes connected with the facts of 
consciousness 1 ' The chasm between the two classes of 
phenomena would still remain intellectually impassable." 

In his latest work (An Introduction to the Classification of 
Animals), published in 1869, Professor Huxley unhesitatingly 

except in the same sense tliat the action of man or of any other intelligent 
being is a first cause. In using such terms I wished to show plainly that I 
contemplated the possibility that the development of the essentially human 
portions of man's structure and intellect may have been determined by the 
directing influence of some higher intelligent beings, acting through natural 
and universal laws. A belief of this nature may or may not have a founda- 
tion, but it is an intelligible theory, and is not, in its nature, incapable of 
proof ; and it rests on facts and arguments of an exactly similar kind to 
those which would enable a sufficiently powerful Intellect to deduce, 
from the existence on the earth of cultivated plants and domestic animals 
the presence of some intelligent being of a higher nature than themselves. 



IX LIMITS OF NATURAL SELECTION IN MAN 207 

adopts the " well founded doctrine that Hfe is the cause and 
not the consequence of organisation." In his celebrated 
article " On the Physical Basis of Life," however, he maintains 
that life is a property of protoplasm, and that protoplasm 
owes its properties to the nature and disposition of its 
molecules. Hence he terms it "the matter of life," and 
believes that aU the physical properties of organised beings 
are due to the physical properties of protoplasm. So far we 
might, perhaps, follow him, but he does not stop here. He 
proceeds to bridge over that chasm which Professor TyndaU 
has declared to be " intellectually impassable," and, by means 
which he states to be logical, arrives at the conclusion that 
our "thoiights a/re the expression of molecular changes in that 
matter of life which is the source of our other vital phenomena." 
Not having been able to find any clue in Professor Huxley's 
writings to the steps by which he passes from those vital 
phenomena, which consists only, in their last analysis, of 
movements of particles of matter, to those other phenomena 
which we term thought, sensation, or consciousness, but 
knowing that so positive an expression of opinion from him 
will have great weight with many persons, I shall endeavour 
to show, with as much brevity as is compatible with clearness, 
that this theory is not only incapable of proof, but is also, as 
it appears to me, inconsistent with accurate conceptions of 
molecular physics. To do this, and in order further to 
develop my views, I shall have to give a brief sketch of the 
most recent speculations and discoveries as to the ultimate 
nature and constitution of matter. 

The Natwe of Matter 
It has been long seen by the deepest thinkers on the 
subject, that atoms, — considered as minute soHd bodies from 
which emanate the attractive and repulsive forces which give 
what we term matter its properties, — could serve no purpose 
whatever ; since it is universally admitted that the supposed 
atoms never touch each other, and it cannot be conceived that 
these homogeneous, indivisible, solid units are themselves the 
ultimate cause of the forces that emanate from their centres. 
As, therefore, none of the properties of matter can be due to 
the atoms themselves, but only to the forces which emanate 



208 NATURAL SELECTION ix 

from tte points in space indicated by the atomic centres, it 
is logical continually to diminish their size till they vanish, 
leaving only localised centres of force to represent them. Of 
the various attempts that have been made to show how the 
properties of matter may be due to such modified atoms 
(considered as mere centres of force), the most successful, 
because the simplest and the most logical, is that of Mr. 
Bayma, who, in his Molecular Mechanics, has demonstrated 
how, from the simple assumption of such centres having 
attractive and repulsive forces (both varying according to 
the same law of the inverse squares as gravitation), and by 
grouping them in symmetrical figures, consisting of a repulsive 
centre, an attractive nucleus, and one or more repulsive 
envelopes, we may explain all the general properties of matter ; 
and, by more and more complex arrangements, even the 
special chemical, electrical, and magnetic properties of special 
forms of matter.^ Each chemical element will thus consist of 
a molecule formed of simple atoms (or as Mr. Bayma terms 
them, to avoid confusion, " material elements ") in greater or 
less number and of more or less complex arrangement ; which 
molecule is in stable equilibrium, but liable to be changed in 
form by the attractive or repulsive influences of difi'erently 
constituted molecules, constituting the phenomena of chemical 
combination, and resulting in new forms of molecule of greater 
complexity and more or less stability. 

Those organic compounds of which organised beings are 
built up consist, as is well known, of matter of an extreme 
complexity and great instability ; whence result the changes 
of form to which it is continually subject. This view en- 
ables us to comprehend the possibility of the phenomena of 
vegetative life being due to an almost infinite complexity of 

1 Mr. Bayma's work, entitled The Elements of MoXecukur Mechanics, was 
putlislied in 1866, and has received less attention than it deserves. It is 
characterised hy great lucidity, ty logical arrangement, and hy comparatively 
simple geometrical and algehraical demonstrations, so that it may be under- 
stood and appreciated with a very moderate knowledge of mathematics. It 
consists of a series of Propositions, deduced from the known properties of 
matter ; from these are derived a number of Theorems, by whose help the 
more complicated Problems are solved. Nothing is taken for granted through- 
out the work, and the only valid mode of escaping from its conclusions is, by 
either disproving the fundamental Propositions, or by detecting fallacies in the 
subsequent reasoning. 



tx LIMITS OF NATURAL SELECTION IN MAN 209 



molecular combinations, subject to definite changes under the 
stimuli of heat, moisture, light, electricity, and probably some 
unknown forces. But this greater and greater complexity, 
even if carried to an infinite extent, cannot, of itself, have the 
slightest tendency to originate consciousness in such molecules 
or groups of molecules. If a material element, or a combina- 
tion of a thousand material elements in a molecule, are alike 
unconscious, it is impossible for us to believe that the mere 
addition of one, two, or a thousand other material elements to 
form a more complex molecule, could in any way tend to 
produce a seK-conscious existence. The things are radically 
unlike, exclusive, and incommensurable. To say that mind is a 
product or function of protoplasm, or of its molecular changes, 
is to use words to which we can attach no clear conception ; 
and those who argue thus should put forth a precise definition 
of matter with clearly enunciated properties, and show that 
the necessary result of a certain complex arrangement of the 
elements or atoms of that matter wiU be the production of self- 
consciousness. There is no escape from this dilemma, — either 
all matter is conscious, or consciousness is, or pertains to, some- 
thing distinct from matter, and in the latter case its presence 
in material forms is a proof of the existence of conscious beings, 
outside of, and independent of, what we term matter.^ 

'■ A friend has suggested that I have not here explained myself sufficiently, 
and objects that life does not exist in matter any more than consciousness, 
and if the one can be produced by the laws of matter, why may not the other ? 
I reply that there is a radical difference between the two. Organic or 
vegetative life consists essentially in chemical transformations and molecular 
motions, occurring tinder certain conditions and in a certain order. The 
matter and the forces which act upon it are for the most part known ; and 
if there are any forces engaged in the manifestation of vegetative life yet 
undiscovered (which is a moot question), we can conceive them as analogous 
to such forces as heat, electricity, or chemical afiSnity, with which we are 
already acquainted. We can thus clearly conceive of the transition from dead 
matter to living matter. A complex mass which suffers decomposition or 
decay is dead, but if this mass has the power of attracting to itself from the 
surrounding medium, matter like that of which it is composed, we have the 
first rudiment of vegetative life. If the mass can do this for a considerable 
time and it its absorption of new matter more than replaces that lost by 
decomposition, and if it is of such a nature as to resist the mechanical or 
chemical forces to which it is usually exposed, and to retain a tolerably 
constant form, we term it a living organism. We can conceive an organism to 
be so constituted, and we can further conceive that any fragments, which may 
be accidentally broken from it, or which may fall away when its bulk has 
become too great for the cohesion of all its parts, may begin to increase anew 

P 



210 ISTATUKAL SELECTION ix 

Matter is Force 

The foregoing considerations lead us to the very 
important conclusion that matter is essentially force, and 
nothing but force; that matter, as popularly understood, 
does not exist, and is, in fact, philosophically inconceivable. 
When we touch matter, we only really experience sensations 
of resistance, implying repulsive force ; and no other sense 
can give us such apparently solid proofs of the reality of 
matter as touch does. This conclusion, if kept constantly 
present in the mind, will be found to have a most important 
bearing on almost every high scientific and philosophical 
problem, and especially on such as relate to our own conscious 
existence. 

and run the same course as the parent mass. This is growth and reproduction 
in their simplest forms ; and from such a simple beginning it is possihle to 
conceive a series of slight modifications of composition, and of internal and 
external forces, which should ultimately lead to the development of more 
complex organisms. The life of such an organism may, perhaps, be nothing 
added to it, but merely the name we give to the result of a balance of internal 
and external forces in maintaining the permanence of the form and structure of 
the individual. The simplest conceivable form of such life would be the dew- 
drop, which owes its existence to the balance between the condensation of 
aqueous vapour in the atmosphere and the evaporation of its substance. If 
either is in excess, it soon ceases to maintain an individual existence. I do 
not maintain that vegetative life is wholly due to such a complex balance of 
forces, hut only that it is conceivable as such. 

With C0N30I0TISNESS the case is very different. Its phenomena are not 
comparable with those of any kind of matter subjected to any of the known 
or conceivable forces of nature ; and we cannot conceive a gradual transition 
from absolute unconsciousness to consciousness, from an unsentient organism 
to a sentient being. The merest rudiment of sensation or self-consciousness 
is infinitely removed from absolutely non- sentient or unconscious matter. 
We can conceive of no physical addition to, or modification of, an unconscious 
mass which should create consciousness ; no step iu the series of changes 
organised matter may undergo, which should bring in sensation where there 
was no sensation or power of sensation at the preceding step. It is because 
the things are utterly incomparable and incommensurable that we can only 
conceive of sensation coming to matter from without, while life may be con- 
ceived as merely a specific combination and co-ordination of the matter and 
the forces that compose the universe, and with which we are separately 
acquainted. We may admit with Professor Huxley that protoplasm is the 
"matter of life" and the cause of organisation, but we cannot admit or con- 
ceive that protoplasm is the primary source of sensation and consciousness, or 
that it can ever of itself become conscious in the same way as we may perhaps 
conceive that it may become alive. 



LIMITS OP NATURAL SELECTION IN MAN 211 



All Force is probably Will-Force 
If we are satisfied that force or forces are all that exist 
in the material universe, we are next led to inqiiire 
what is force 1 We are acquainted with two radically 
distinct or apparently distinct kinds of force — the first 
consists of the primary forces of nature, such as gravitation, 
cohesion, repulsion, heat, electricity, etc. ; the second is 
our own will-force. Many persons will at once deny that 
the latter exists. It will be said that it is a mere trans- 
formation of the primary forces before alluded to ; that the 
correlation of forces includes those of animal life, and that 
mil itself is but the result of molecular change in the brain. 
I think, however, that it can be shown that this latter asser- 
tion has neither been proved, nor even been proved to be 
possible ; and that in making it, a great leap in the dark has 
been taken from the known to the unknown. It may be at 
once admitted that the jnuscular force of animals and men is 
merely the transformed energy derived from the primary 
forces of nature. So much has been, if not rigidly proved, 
yet rendered highly probable, and it is in perfect accordance 
with all our knowledge of natural forces and natural laws. 
But it cannot be contended that the physiological balance- 
sheet has ever been so accurately struck, that we are entitled 
to say, not one-thousandth part of a grain more of force has 
been exerted by any organised body, or in any part of it, than 
has been derived from the known primary forces of the 
material world. If that were so, it would absolutely negative 
the existence of will ; for if wiU is anything, it is a power that 
directs the action of the forces stored up in the body, and it is 
not conceivable that this direction can take place, without the 
exercise of some force in some part of the organism. How- 
ever delicately a machine may be constructed, with the most 
exquisitely contrived detents to release a weight or spring by 
the exertion of the smallest possible amount of force, some 
external force will always be required; so, in the animal 
machine, however minute may be the changes required in 
the cells or fibres of the brain, to set in motion the nerve 
currents which loosen or excite the pent-up forces of certain 
muscles, some fffrce must be required to ejQfect those changes. 



212 NATURAL SELECTION ix 

If it is said, "those changes are automatic, and are set in 
motion by external causes," then one essential part of our 
consciousness, a certain amount of freedom in willing, is 
annihilated ; and it is inconceivable how or why there should 
have arisen any consciousness or any apparent will, in such 
purely automatic organisms. If this were so, our apparent 
WILL would be a delusion, and Professor Huxley's beUef 
" that our volition counts for something as a condition of the 
coiu"se of events," would be fallacious, since our volition would 
then be but one link in the chain of events, counting for 
neither more nor less than any other link whatever. 

If, therefore, we have traced one force, however minute, 
to an origin in our own "will, while we have no knowledge of 
any other primary cause of force, it does not seem an improb- 
able conclusion that all force may be wiU-f orce ; and thus, 
that the whole universe is not merely dependent on, but actu- 
ally is, the WILL of higher intelligences or of one Supreme In- 
telligence. It has been often said that the true poet is a seer ; 
and in the noble verse of an American poetess we find ex- 
pressed what may prove to be the highest fact of science, the 
noblest truth of philosophy : 

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. 
It leaps to life in grass and flowers, 

Through every grade of heing runs, 
While from Creation's radiant towers 

Its glory flames in Stars and Suns. 

Coiiclusion 

These speculations are usually held to be far beyond the 
bounds of science ; but they appear to me to be more legiti- 
mate deductions from the facts of science than those which 
consist in reducing the whole universe, not merely to matter, 
but to matter conceived and defined so as to be philosophically 
inconceivable. It is surely a great step in advance, to get 
rid of the notion that matter is a thing of itself, which can 
exist per se, and must have been eternal, since it is supposed 
to be indestructible and ^uncreated, — that force, or the forces 



rx LIMITS OF NATURAL SELECTION IN MAN 213 

of nature, are another thing, given or added to matter, or else 
its necessary properties, — and that mind is yet another thing, 
either a product of this matter and its supposed inherent 
forces, or distinct from and co -existent with it; — and to be 
able to substitute for this complicated theory, which leads to 
endless dilemmas and contradictions, the far simpler and 
more consistent belief, that matter, as an entity distinct from 
force, does not exist ; and that force is a product of MIND. 
Philosophy had long demonstrated our incapacity to prove 
the existence of matter, as usufl,Ily conceived ; while it ad- 
mitted the demonstration to each of us of our own self-con- 
scious,-spiritual existence. Science has now worked its way 
up to the same result, and this agreement between them 
should give us some confidence in their combined teaching. 

The view we have now arrived at seems to me more grand 
and sublime, as well as far simpler, than any other. It ex- 
hibits the universe as a universe of intelligence and will- 
power ; and by enabling us to rid ourselves of the impossi- 
bility of thinking of mind, but as connected with our old 
notions of matter, opens up infinite possibilities of existence, 
connected with infinitely varied manifestations of force, totally 
distinct from, yet as real as, what we term matter. 

The grand law of continuity which we see pervading our 
universe would lead us to infer infinite gradations of existence, 
and to people all space with intelligence and wiU-power ; and, 
if so, we shaU have no difficulty in believing that for so noble 
a purpose as the progressive development of higher and higher 
intelligences, those primal and general will-forces, which have 
sufficed for the production of the lower animals, should have 
been guided into new channels and made to converge in 
definite directions. And if, as seems to me probable, this 
has been done, I cannot admit that it in any degree affects 
the truth or generality of Mr. Darwin's great discovery. It 
merely shows that the laws of organic development have 
been occasionaUy used for a special end, just as man uses 
them for his special endsj and I do not see that the law 
of natural selection can be said to be disproved, if it can 
be shown that man does not owe his entire physical and 
mental development to its unaided action, any more than 
it is disproved by the existence of *tl^ poodle or the pouter 



214 NATURAL SELECTION ix 

pigeon, the production of which are equally beyond its 
undirected power. 

The objections which in this essay I have taken to the 
view that the same law which appears to have sufficed for 
the development of animals has been alone the cause of man's 
superior physical and mental nature, will, I have no doubt, 
be overruled and explained away. But I venture to think 
they will nevertheless maintain their ground, and that they 
can only be met by the discovery of new facts or new laws, 
of a nature very different from any yet known to us. I can 
only hope that my treatment of the subject, though neces- 
sarily very meagre, has been clear and intelligible ; and that 
it may prove suggestive both to the opponents and to the 
upholders of the theory of natural selection. 



TROPICAL NATUEE AND OTHER ESSAYS 



THE CLIMATE AND PHYSICAL ASPECTS OF THE EQTJATOEIA.L 

ZONE 

The three Climatal Zones of the Earth — Temperature of the Equatorial 
Zone — Cavises of the Uniform High Temperature near the Equator — 
Influence of the Heat of the Soil — Influence of the Aqueous Vapour 
of the Atmosphere — Influence of Winds on the Temperature of the 
Equator — Heat due to the Condensation of Atmospheric Vapour — 
General features of the Equatorial Climate — Uniformity of the Equa- 
torial Climate in all parts of the Globe — Eff'eots of Vegetation on 
Climate — Short TwUight of the Equatorial Zone — The aspect of the 
Equatorial Heavens — Intensity of Meteorological Phenomena at the 
Equator — Concluding Remarks. 

It is difficult for an inliabitant of our temperate land to 
realise either the sudden and violent contrasts of the arctic 
seasons or the wonderful uniformity of the equatorial climate. 
The lengthening or the shortening days, the ever -changing 
tints of spring, summer, and autumn, succeeded by the leafless 
boughs of winter, are constantly recurring phenomena which 
represent to us the established course of nature. At the 
equator none of these changes occur ; there is a perpetual 
equinox and a perpetual summer, and were it not for variations 
in the quantity of rain, in the direction and strength of the 
winds, and in the amount of sunshine, accompanied by corre- 
sponding slight changes in the development of vegetable and 
animal life, the monotony of nature would be extreme. 

In the present chapter it is proposed to describe the chief 
peculiarities which distinguish the equatorial from the tem- 
perate climate, and to explain the causes of the difierence 
between them, — causes which are by no means of so simple a 
natiire as are usually imagined. 



218 TROPICAL NATURE i 

The Three Glimatal Zones of the Earth 

The three great divisions of the earth — the tropical, the 
temperate, and the frigid zones — may be brieily defined as 
the regions of uniform, of variable, and of extreme physical 
conditions respectively. They are primarily determined by 
the circumstance of the earth's axis not being perpendicular 
to the plane in which it moves roxuid the sun ; whence it 
follows that during one half of its revolution the north pole, 
and during the other half the south pole, is turned at a con- 
siderable angle towards the source of light and heat. This 
inclination of the axis on which the earth rotates is usually 
defined by the inclination of the equator to the plane of the 
orbit, termed the obliquity of the ecliptic. The amount of 
this obliquity is 23|^ degrees, and this measures the extent on 
each side of the equator of what are called the tropics, because 
within these limits the sun becomes vertical at noon twice a 
year, and at the extreme limit once a year, while beyond this 
distance it is never vertical. It will be evident, however, 
from the nature of the case, that the two lines which mark 
the limits of the geographical " tropics " vrill not define any 
abrupt change of climate or physical conditions, such as 
characterise the tropical and temperate zones in their full 
development. There vrill be a gradual transition from one to 
the other, and in order to study them separately and contrast 
their special features we must only take into account the 
portion of each in which these are most fully exhibited. For 
the temperate zone we may take all countries situated be- 
tween 35° and 60° of latitude, which in Europe will include 
every place between Christiana and Algiers, the districts 
farther south forming a transitional belt in which temperate 
and tropical features are combined. In order to study the 
special features of tropical nature, on the other hand, it will 
be advisable to confine our attention mainly to that portion 
of the globe which extends for about twelve degrees on each 
side of the equator, in which all the chief tropical phenomena 
dependent on astronomical causes are most fully manifested, 
and which we may distinguish as the " equatorial zone." In 
the debatable ground between these two well-contrasted belts 
local causes have a preponderating influence ; and it would 



I CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 219 

not be difficult to point out localities witHn the temperate 
zone of our maps, which exhibit all the chief characteristics of 
tropical nature to a greater degree than other localities which 
are, as regards geographical position, tropical. 

Temperature of the Equatorial Zone 

The most characteristic, as it is the most important feature 
in the physical conditions of the great equatorial zone, 
is the wonderful uniformity of its temperature, alike 
throughout the changes of day and night, and from one 
part of the year to another. As a general rule, the 
greatest heat of the day does not exceed 90° or 91° Fahr., 
while it seldom falls during the night below 74° Fahr. It 
has been found by hourly observations carried on for three 
years at the meteorological observatory established by the 
Dutch government at Batavia, that the extreme range of 
temperature in that period was only 27° Fahr., the maximum 
being 95° and the minimum 68°. But this is, of course, very 
much beyond the usual daily range of the thermometer, which 
is, on the average, only a little more than 11° Fahr. ; being 
12"6° in September, when it is greatest, and only 8'1° in 
January, when it is least. 

Batavia, being situated between six and seven degrees 
south of the equator, may be taken as affijrding a fair example 
of the climate of the equatorial zone ; though, being in an 
island, it is somewhat less extreme than many continental 
localities. Observations made at Para, which is on the South 
American Continent, and close to the equator, agree, however, 
very closely with those at Batavia ; but at the latter place all 
the observations were made with extreme care and with the 
best instruments, and are therefore preferred as being 
thoroughly trustworthy.^ The accompanying diagram, show- 
ing by curves the monthly means of the highest and lowest 
daily temperatures at Batavia and London, is very instructive ; 
more especially when we consider that the maximum of tem- 
perature is by no means remarkably different in the two 

1 " Observations made at the Magnetical and Meteorological Observatory 
at Batavia. Published by order of the Government of Netherlands, India. 
Vol. I. Meteorological, from Jan. 1866 to Dec. 1868 ; and Magnetical, from 
July 1867 to June 1870. By Dr. P. A. Bergsma, Batavia, 1871." This 
fine work is entirely in English. 



220 



TKOPICAL NATURE 



MmOify Mexm. Tempemtare at Bcdavicu &Iondo7i. 




1 CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 221 

places, 90° Fahr. being sometimes reached with us and not 
being often very much exceeded at Batavia. 

Causes of the uniform High Temperature near the Eguatm- 

It is popularly supposed that the uniform high temperature 
of the tropics is sufficiently explained by the greater altitude, 
and therefore greater heating-power of the midday sun ; but 
a little consideration will show that this alone by no means 
accounts for the phenomenon. The island of Java is situated 
in from six and a half to eight and a half degrees of south 
latitude, and in the month of June the sun's altitude at noon 
will not be more than from 58° to 60°. In the same month 
at London, which is fifty -one and a half degrees of north 
latitude, the sun's noonday altitude is 62°. But besides this 
difference of altitude in favour of London there is a stUl more 
important difference, for in Java the day is only about eleven 
and a half hours long in the month of June, while at London 
it is sixteen hours long, so that the total amount of sun-heat 
received by the earth must be then very much greater at 
London than at Batavia. Yet at the former place the mean 
temperature of the day and night is under 60° Fahr., while 
in the latter place it is 80° Fahr., the daily maximum being 
on the average in the one case about 68° and in the other 
about 89°. 

Neither does the temperature at the same place depend 
upon the height of the sun at noon ; for at Batavia it is nearly 
vertical during October and February, but these are far from 
being the hottest months, which are May, June, and Sep- 
tember, while December, January, and February are the 
coldest months, although then the sun attains nearly its 
greatest altitude. It is evident, therefore, that a difference of 
30° in the altitude of the sun at noon, at different times of 
the year, has no apparent influence in raising the temperature 
of a place near the equator, and hence we conclude that other 
agencies are at work which often completely neutralise the 
effect which increased altitude must undoubtedly exert. 

There is another important difference between the tem- 
perate and tropical zones, in the direct heating effect of the 
sun's rays independently of altitude. In England the noon- 
day sun in the month of June rarely inconveniences us or 



222 TEOPIOAL NATUEE 



produces any burning of the skin, while in the tropics at 
almost any hour of the day, and when the sun has an eleva- 
tion of only 40° or 50°, exposure to it for a few minutes will 
scorch a European so that the skin turns red, becomes painful, 
and often blisters or peels off. Almost every visitor to the 
tropics suffers from incautious exposure of the neck, the leg, 
or some other part of the body to the sun's rays, which there 
possess a power as new as it is at first sight inexplicable, for 
it is not accompanied by any extraordinary increase in the 
temperature of the air. 

These very different effects, produced by the same amount 
of sun-heat poured upon the earth in different latitudes, is 
due to a combination of causes. The most important of these 
are, probably, — the constant high temperature of the soil and 
of the surface-waters of the ocean, — the great amount of 
aqueous vapour in the atmosphere, — the great extent of the 
intertropical regions which cause the winds that reach the 
equatorial zone to be always warm, — and the latent heat 
given out during the formation of rain and dew. We will 
briefly consider the manner in which each of these causes 
contributes to the high degree and great uniformity of the 
equatorial temperature. 

Influence of the Heat of the Soil 

It is well known that at a very moderate depth the soil 
maintains a uniform temperature during the twenty -four 
hours, while at a greater depth even the annual inequalities 
disappear, and a uniform temperature, which is almost exactly 
the mean temperature of the air in the same locality, is con- 
stantly maintained throughout the year. The depth at which 
this uniform temperature is reached is greater as the annual 
range of temperature is greater, so that it is least near the 
equator, and greatest in localities near the arctic circle, where 
the greatest difference between summer and winter tempera- 
ture prevails. In the vicinity of the equator, where the 
annual range of the thermometer is so small as we have seen 
it to be at Batavia, the mean temperature of about 80° Fahr. 
is reached at a depth of four or five feet. The surplus heat 
received during the day is therefore conducted downwards 
very slowly, the surface soil becomes greatly super-heated. 



I CLIMATE AND ASPECTS OF THfi EQUATORIAL ZONE 223 

and a large portion of this heat is given out at night and thus 
keeps up the high temperature of the air when the sun has 
ceased to warm the earth. In the temperate zones, on the 
other hand, the stratum of uniform earth -temperature lies 
very deep. At Geneva it is not less than from thirty to 
forty feet, and with us it is probably fifty or sixty feet, and 
the temperature found there is nearly forty degrees lower 
than at the equator. This great body of cool earth absorbs 
a large portion of the surface heat during the summer, and 
conducts it downwards with comparative rapidity, and it is 
only late in the year (in Jidy and August), when the upper 
layers of the soil have accumulated a surplus store of solar 
heat, that a sufficient quantity is radiated at night to keep up 
a rather high temperatiure in the absence of the sun. At the 
equator, on the other hand, this radiation is always going on, 
and earth-heat is one of the most important of the agencies 
which tend to equalise the equatorial climate. 

Influence of the Aqueous Vapour of the Atmosphere 

The aqueous vapour which is always present in consider- 
able quantities in the atmosphere, exhibits a singular and 
very important relation to solar and terrestrial heat. The 
rays of the sun pass through it unobstructed to the earth ; 
but the warmth given off by the heated earth is very largely 
absorbed by it, thus raising the temperature of the air ; and 
as it is the lower strata of air which contain most vapour, 
these act as a blanket to the earth, preventing it from losing 
heat at night by radiation into space. During a large part 
of the year the air in the equatorial zone is nearly saturated 
with vapour, so that, notwithstanding the heat, salt and 
sugar become liquid, and all articles of iron get thickly coated 
with rust. Complete saturation being represented by 100, 
the daily average of greatest humidity at Batavia reaches 96 
in January and 92 in December. In January, which is the 
dampest month, the range of humidity is small (77 to 96), 
and at this time the range of temperature is also least ; while 
in September, with a greater daily range of humidity (62 to 
92) the range of temperature is the greatest, and the lowest 
temperatures are recorded in this and the preceding month. 
It is a curious fact that in many parts of England the degree 



224 1:ropical nature 



of humidity, as measured by the comparative saturation of the 
air, is as great as that of Batavia or even greater. A register 
kept at Clifton during the years 1853-1862 shows a mean 
humidity in January of 90, while the highest monthly mean 
for. the four years at Batavia was 88 ; and while the lowest 
of the monthly means at Clifton was 79 '1, the lowest at 
Batavia was 78 "9. These figures, however, represent an 
immense difi"erence in the guantity of vapour in every cubic 
foot of air. In January at Clifton, with a temperature of 35° 
to 40° Fahr., there would be only about 4 to 4^ grains of 
vapour per cubic foot of air, while at Batavia, with a tem- 
perature from 80° to 90° Fahr., there would be about 20 
grains in the same quantity of air. The most important fact, 
however, is, that the capacity of air for holding vapour in 
suspension increases more rapidly than temperature increases, 
so that a fall of ten degrees at 50° Fahr. will lead to the con- 
densation of about 1 J grain of vapour per cubic foot, while a 
similar fall at 90° Fahr. will set free 6| grains. We can thus 
understand how it is that the very moderate fall of the ther- 
mometer during a tropical night causes heavier dews and a 
greater amount of sensible moisture than are ever experienced 
during much greater variations of temperature in the tem- 
perate zone. It is this large quantity of vapour in the 
equatorial atmosphere that keeps up a genial warmth 
throughout the night by preventing the radiation into space 
of the heat absorbed by the surface soil during the day. 
That this is really the case is strikingly proved by what occurs 
in the plains of Northern India, where the daily maximum of 
heat is far beyond anything experienced near the equator, 
yet, owing to the extreme dryness of the atmosphere, the clear 
nights are very cold, radiation being sometimes so rapid that 
water placed in shallow pans becomes frozen over. 

As the heated earth, and everything upon its surface, does 
not cool so fast when surrounded by moist as by dry air, it 
follows that even if the quantity and intensity of the solar 
rays falling upon two given portions of the earth's surface are 
exactly equal, yet the sensible and effective heat produced in 
the two localities may be very different according as the 
atmosphere contains much or little vapour. In the one case 
the heat is absorbed more rapidly than it can escape by radia- 



I CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 225 

tion ; in the other case it radiates away into space, and is lost, 
more rapidly than it is being absorbed. In both cases an 
equilibriuni will be arrived at, but in the one case the result- 
ing mean temperature will be much higher than in the other. 
Thus we can understand the burning effects of the sun's rays 
in the tropics, since it results from the inability of the sMn 
to part with the heat, either by radiation, evaporation, or 
absorption, as fast as it is received, and thus a temperature is 
quickly reached which disorganises the delicate structures of 
the epidermis. 

Influence of Winds on the Temperatwe of the Equator 
The distance from the northern to the southern tropics 
being considerably more than three thousand miles, and the 
area of the intertropical zone more than one-third the whole 
area of the globe, it becomes hardly possible for any currents 
of air to reach the equatorial belt without being previously 
warmed by contact with the earth or ocean, or by mixture 
with the heated surface-air which is found in all intertropical 
and sub-tropical lands. This warming of the air is rendered 
more certain and more effective by the circumstance that all 
currents of air coming from the north or south have their 
direction changed owing to the increasing rapidity of the 
earth's rotational velocity, so that they reach the equator as 
easterly winds, and thus pass obliquely over a great extent of 
the heated surface of the globe. The causes that produce the 
westerly monsoons act in a similar manner, so that on the 
equator direct north or south winds, except as local land and 
sea-breezes, are almost unknown. The Batavia observations 
show that for ten months in the year the average direction 
of the wind varies only between 5° and 30° from due east or 
west, and these are also the strongest winds. In the two 
months — March and October — when the winds are northerly, 
they are very light, and are probably in great part local 
sea-breezes, which, from the position of Batavia, must 
come from the north over about two thousand miles of warm 
land and sea. As a rule, therefore, every current of air at 
or near the equator has passed obliquely over an immense 
extent of tropical surface and is thus necessarily a warm 
wind. 

Q 



226 TROPICAL NATURE 1 

In the north temperate zone, on the other hand, the winds 
are always cool, and often of very low temperature even in 
the height of summer, due probably to their coming from 
colder northern regions as easterly winds, or from the upper 
parts of the atmosphere as westerly winds ; and this constant 
supply of cool air, combined with quick radiation through a 
dryer atmosphere, carries off the solar heat so rapidly that an 
equilibrium is only reached at a comparatively low tempera- 
ture. In the equatorial zone, on the contrary, the heat 
accumulates, on account of the absence of any medium of 
sufficiently low temperature to carry it off rapidly, and it thus 
soon reaches a point high enough to produce those scorching 
effects which are so puzzling when the altitude of the sun or 
the indications of the thermometer are alone considered. 
Whenever, as is sometimes the case, exceptional cold occurs 
near the equator, it can almost always be traced to the in- 
fluence of currents of air of unusually low temperature. Thus 
in July near the Aru islands, the writer experienced a strong 
south-east wind which almost neutralised the usual effects of 
tropical heat, although the weather was bright and sunny. 
But the wind, coming direct from the southern ocean during 
its winter without acquiring heat by passing over land, was 
necessarily of a low temperature. Again, Mr. Bates informs 
us that in the Upper Amazon in the month of May there is a 
regularly recurring south wind which produces a remarkable 
lowering of the usual equatorial temperature. But owing to 
the increased velocity of the earth's surface at the equator a 
south wind there must have been a south-west wind at it» 
origin, and this would bring it directly from the high chain 
of the Peruvian Andes during the winter of the southern 
hemisphere. It is therefore probably a cold mountain wind, 
and blowing as it does over a continuous forest, it has been 
unable to acquire the usual tropical warmth. 

The cause of the striking contrast between the climates of 
equatorial and temperate lands at times when both are 
receiving an approximately equal amount of solar heat may 
perhaps be made clearer by an illustration. Let us suppose 
there to be two reservoirs of water, each supplied by a pipe 
which pours into it a thousand gallons a day, but which runs 
only during the daytime, being cut off at night. The reser- 



I CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 227 



voirs are both leaky, but while the one loses at the rate of 
nine hundred gallons in the twenty-four hours, the other loses 
at the rate of eleven hundred gallons in the same time, sup- 
posing that both are kept exactly half full and thus subjected 
to the same uniform water-pressure. If now both are left to 
be supplied by the above-mentioned pipes the result will be, 
that in the one which loses by leakage less than it receives 
the water will rise day by day till the increased pressure 
causes the leakage to increase to such an extent as exactly to 
balance the supply ; wMle in the other the water will sink till 
the decreasing pressure causes the leakage to decrease tiU it 
also just balances the supply, when both will remain stationary, 
the one at a high the other at a low average level, each rising 
during the day and sinking again at night. Just the same 
thing occurs with that great heat-reservoir the earth, whose 
actual temperature at any spot will depend, not alone upon 
the quantity of heat it receives, but on the balance between 
its constantly varying waste and supply. We can thus under- 
stand how it is that, although in the months of June and 
July, Scotland in latitude 57° north receives as much sun- 
heat as Angola or Timor in latitude 10° south, and for a much 
greater number of hours daily, yet in the latter countries 
the mean temperature will be about 80° Fahr., with a daily 
maximum of 90° to 95°, while in the former the mean will be 
about 60° Fahr., with a daily maximum of 70° or 75° ; and, 
while in Scotland exposure to the fuU noon-day sun produces 
no unpleasant heat-sensations, a similar exposure in Timor at 
any time between 9 A.M. and 3 P.M. would blister the skin in a 
few minutes almost as effectually as the application of scalding 
water. 

Heat due to the Condensation of Atmospheric Vapour 

Another cause which tends to keep up a uniform high tem- 
perature in the equatorial, as compared with the variable 
temperatures of the extra-tropical zones, is the large amount 
of heat liberated during the condensation of the aqueous 
vapour of the atmosphere in the form of rain and dew. 
Owing to the frequent near approach of the equatorial atmos- 
phere to the saturation point, and the great amount of vapour 
its high temperature enables it to hold in suspension, a very 



228 



TROPICAL NATURE 



slight fall of the thermometer is accompanied by the conden- 
sation of a large absolute quantity of atmospheric vapour, so 



M>n3ify BcdnfalL cub Londorv ccnABaMvia . 




that copious- dews and heavy showers of rain are produced at 
comparatively high temperatures, and even at the sea level. 



I CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 229 

The drops of rain rapidly increase in size while falling through 
the saturated atmosphere ; and during this process as well as 
by the formation of dew, the heat which retained the water 
in the gaseous form, and was insensible while doing so, is 
liberated, and thus helps to keep up the high temperature of 
the air. This production of heat is almost always going on. 
In fine weather the nights are always dewy, and the diagram 
on the precediag page, showing the mean monthly rainfall at 
Batavia and Greenwich, proves that this source of increased 
temperature is present during every month in the year, since 
the lowest monthly fall at the former place is almost equal to 
the highest monthly fall at the latter. 

It may perhaps be objected that evaporation must absorb 
as much heat as is afterwards liberated by condensation, and 
this is true ; but as evaporation and condensation occur usually 
at different times and in different places, the equalising effect 
is still very important. Evaporation occurs chiefly during 
the hottest sunshine, when it tends to moderate the extreme 
heat, while condensation takes place chiefly at night in the 
form of dew and rain, when the liberated heat helps to make 
up for the loss of the direct rays of the sun. Again the most 
copious condensation both of dew and rain is greatly influ- 
enced by vegetation and especially by forests, and also by the 
presence of hiUs and mountains, and is therefore greater on 
land than on the ocean, while evaporation is much greater on 
the ocean, both on account of the less amount of cloudy 
weather and because the air is more constantly in motion. 
This is particularly the case throughout that large portion of 
the tropical and subtropical zones where the trade-winds con- 
stantly blow, as the evaporation must there be enormous 
while the quantity of rain is very small. It follows, then, 
that on the equatorial land-surface there will be a consider- 
able balance of condensation over evaporation, which must 
tend to the general raising of the temperature, and, owing to 
the condensation being principally at night, not less power- 
fully to its equalisation. 

General Features of the Egvatorial Climate 

The various causes now enumerated are sufficient to enable 
us to understand how the great characteristic features of the 



230 TROPICAL NATURE 



climate of the equatorial zone are brought about, how it is 
that so high a temperature is maintained during the absence 
of the sun at night, and why so little effect is produced by 
the sun's varying altitude during its passage from the northern 
to the southern tropic. In this favoured zone the heat is 
never oppressive, as it so often becomes on the borders of the 
tropics ; and the large absolute amount of moisture always 
present in the air is almost as congenial to the health of man 
as it is favourable to the growth and development of vegeta- 
tion. ^ Again, the lowering of the temperature at night is so 
regular and yet so strictly Umited in amount, that, although 
never cold enough to be unpleasant, the nights are never so 
oppressively hot as to prevent sleep. During the wettest 
months of the year, it is rare to have many days in succession 
without some hours of sunshine, while even in the driest 
months there are occasional showers to cool and refresh the 
overheated earth. As a result of this condition of the earth 
and atmosphere, there is no check to vegetation, and little if 
any demarcation of the seasons. Plants are all evergreen; 
flowers and fruits, although more abundant at certain seasons, 
are never altogether absent ; while many annual food-plants 
as well as some fruit-trees produce two crops a year. In 
other cases, more than one complete year is required to 
mature the large and massive fruits, so that it is not uncom- 
mon for fruit to be ripe at the same time that the tree is 
covered with flowers in preparation for the succeeding crop. 
This is the case with the Brazil nut tree in the forests of the 
Amazon, and with many other tropical as with a few tern- ' 
perate fruits. 

Uniformity of the Equatorial Climate in all Pa/rts of the Globe 
The description of the climatal phenomena of the equatorial 
zone here given has been in great part drawn from long 
personal experience in South America and in the Malay 
Archipelago. Over a large portion of these countries the 
same general features prevail, only modified by varying local 

1 Where the inhabitants adapt their mode of life to the peculiarities of 
the climate, aa la the case with the Dutch in the Malay Archipelago, they 
enjoy as rohust health as in Europe both in the case of persons bom in 
Europe and of those who for generations have lived under a vertical sun. 



I CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 231 

conditions. Whether we are at Singapore or Batavia, in the 
Moluccas or New Guinea, at Para, at the sources of the 
Rio Negro, or on the Upper Amazon, the equatorial climate 
is essentially the same, and we have no reason to believe that 
it materially differs in Guinea or the Congo. In certain 
localities, however, a more contrasted wet and dry season 
prevails, with a somewhat greater range of the thermometer. 
This is generally associated with a sandy soil, and a less dense 
forest, or with an open and more cultivated country. The 
open sandy country with scattered trees and shrubs or occa- 
sional thickets, which is found at Santarem and Monte-Alegre 
on the lower Amazon, are examples, as weU as the open 
cultivated plains of Southern Celebes ; but in both cases the 
forest country in adjacent districts has a moister and more 
uniform climate, so that it seems probable that the nature of 
the soil or the artificial clearing away of the forests, are 
important agents in producing the departure from the typical 
equatorial climate observed in such districts. 

Effects of Vegetation on Climate 

The almost rainless district of Ceara on the north-east coast 
of Brazil, and only a few degrees south of the equator, is a strik- 
ing example of the need of vegetation to react on the rainfall. 
We have here no apparent cause but the sandy soil and bare 
hills, which, when heated by the equatorial sun, produce ascend- 
ing currents of warm air and thus prevent the condensation of 
the atmospheric vapour, to account for such an anomaly ; and 
there is probably no district where judicious planting would 
produce such striking and beneficial effects. In Central India 
the scanty and intermittent rainfall, with its fearful accom- 
paniment of famine, is perhaps in great part due to the 
absence of a sufficient proportion of forest -covering to the 
earth's surface ; and it is by a systematic planting of all the 
hill- tops, elevated ridges, and higher slopes that we shall 
probably cure the evil. This would almost certainly induce 
an increased rainfall; but even more important and more 
certain is the action of forests in checking evaporation from 
the soil and causing perennial springs to flow, which may be 
collected in vast storage tanks and serve to fertilise a great 
extent of country ; whereas tanks without regular rainfall or 



232 TROPICAL NATURE 



permanent springs to supply them are worthless. In the 
colder parts of the temperate zones the absence of forests is 
not so much felt, because the hills and uplands are naturally 
clothed with a thick coating of turf or peat which absorbs 
moisture and does not become overheated by the sun's rays, 
and the rains are seldom violent enough to strip this protect- 
ive covering from the surface. In tropical and even in 
warm-temperate countries, on the other hand, the rains are 
periodical and often of excessive violence for a short period ; 
and when the forests are cleared away the torrents of rain 
soon strip off the vegetable soil, and thus destroy in a few 
years the fertility which has been the growth of many cen- 
turies. The bare subsoil becoming heated by the sun, every 
particle of moisture which does not flow ofi' is evaporated, and 
this again reacts on the climate, producing long-continued 
droughts only relieved by sudden and violent storms, which 
add to the destruction and render all attempts at cultivation 
unavailing. Wide tracts of fertile land in the south of Europe 
have been devastated in this manner, and have become abso- 
lutely uninhabitable. Knowingly to produce such disastrous 
results would be a far more serious off'ence than any destruc- 
tion of property which human labour has produced and can 
replace ; yet we have ignorantly allowed such extensive clear- 
ings for cofiee cultivation in India and Ceylon as to cause 
the destruction of much fertile soil, which human labour 
cannot replace, and which will surely, if not checked in time, 
lead to the deterioration of the climate and the permanent 
impoverishment of the country.'- 

Short Twilight of the Equatorial Zone 

One of the phenomena which markedly distinguish the 
equatorial from the temperate and polar zones is the 
shortness of the twilight and consequent rapid transition 
from day to night and from night to day. As this depends 
only on the fact of the sun descending vertically instead 
of obliquely below the horizon, the difference is most 
marked when we compare our midsummer twilight with 

' For a terrible picture of the irreparable devastation caused by the reckless 
clearing of forests, see the third chapter of Mr. Marsh's work, The Earth as 
Modified hy Human Action. 



r CLIMATE AND ASPECTS OE THE EQUATOEIAL ZONE 283 



that of the tropics. Even with us the duration of twilight 
is very much shorter at the time of the equinoxes, and 
it is probably not much more than a third shorter than this 
at the equator. Travellers usually exaggerate the short- 
ness of the tropical twilight, it being sometimes said that if 
we turn a page of the book we are reading when the 
sun disappears, by the time we turn over the next page 
it will be too dark to see to read. With an average book 
and an average reader this is certainly not true, and it 
wUl be well to describe as correctly as we can what really 
happens. 

In fine weather the air appears to be somewhat more 
transparent near the equator than with us, and the intensity 
of sunlight is usually very great up to the moment when the 
solar orb touches the horizon. As soon as it has disappeared 
the apparent gloom is proportionally great, but this hardly in- 
creases perceptibly during the first ten minutes. During the 
next ten minutes, however, it becomes rapidly darker, and at 
the end of about half an hour from sunset the complete darkness 
of night is almost reached. In the morning the changes are 
perhaps even more striking. Up to about a quarter past five 
o'clock the darkness is complete ; but about that time a few 
cries of birds begin to break the silence of night, perhaps 
indicating that signs of davni are perceptible in the eastern 
horizon. A little later the melancholy voices of the goat- 
suckers are heard, varied croaMngs of frogs, the plaintive 
whistle of mountain thrushes, and strange cries of birds or 
mammals peculiar to each locality. About half-past five the 
first glimmer of light becomes perceptible ; it slowly becomes 
lighter, and then increases so rapidly that at about a quarter 
to six it seems full daylight. For the next quarter of an 
hour this changes very little in character ; when, suddenly, the 
sun's rim appears above the horizon decking the dew-laden 
foliage with glittering gems, sending gleams of golden light 
far into the woods, and waking up all nature to life and 
activity. Birds chirp and flutter about, parrots scream, 
monkeys chatter, bees hum among the flowers, and gorgeous 
butterflies flutter lazily along or sit with fully expanded 
wings exposed to the warm and invigorating rays. The first 
hour of morning in the equatorial regions possesses a charm 



234 TROPICAL NATURE t 

and a beauty that can never be forgotten. All nature seems 
refreshed and strengthened by the coolness and moisture of 
the past night ; new leaves and buds unfold almost before the 
eye, and fresh shoots may often be observed to have grown 
many inches since the preceding day. The temperature is the 
most delicious conceivable. The slight chill of early dawn, 
which was itself agreeable, is succeeded by an invigorating 
warmth; and the intense sunshine lights up the glorious 
vegetation of the tropics, and realises all that the magic art of 
the painter or the glowing words of the poet have pictured as 
their ideals of terrestrial beauty. 

The Aspect of the Equatorial Heavens 

Within the limits of the equatorial zone the noonday sun is 
truly vertical twice every year, and for several months it passes 
so near the zenith that the difference can hardly be detected 
without careful observation of the very short shadows of vertical 
objects. The absence of distinct horizontal shadows at noon, 
which thus characterises a considerable part of the year, is 
itself a striking phenomenon to an inhabitant of the temperate 
zones ; and equally striking is the changed aspect of the starry 
heavens. The grand constellation Orion passes vertically 
overhead, while the Great Bear is only to be seen low down 
in the northern heavens, and the Pole star either appears close 
to the horizon or has altogether disappeared, according as we 
are north or south of the equator. Towards the south the 
Southern Cross, the Magellanic clouds, and the jet-black 
" coal sacks " are the most conspicuous objects invisible in our 
northern latitudes. The same cause that brings the sun 
overhead in its daily march equally affects the planets, which 
appear high up towards the zenith far more frequently than 
with us, thus affording splendid opportunities for telescopic 
observation. 

Intensity of Meteorological Fhenomena at the Equator 

The excessive violence of meteorological phenomena gene- 
rally supposed to be characteristic of the tropics is not by any 
means remarkable in the equatorial zone. Electrical disturb- 
ances are much more frequent, but not generally more violent 
than in the temperate regions. The wind-storms are rarely 



I CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 23S 

of excessive violence, as might in fact be inferred from the 
extreme steadiness of the barometer, whose daily range at 
Batavia rarely exceeds one -eighth of an inch, while the 
extreme range during three years was less than one-third of 
an inch ! The amount of the rainfall is very great, seventy 
or eighty inches in a year being a probable average ; and as 
the larger part of this occurs during three or four months, 
individual rainfalls are often exceedingly heavy. The greatest 
faU recorded at Batavia during three years was three inches 
and eight-tenths in one hour,^ but this was quite exceptional, 
and even half this quantity is very unusual. The greatest 
rainfall recorded in twenty-four hours is seven inches and a 
quarter ; but more than four inches in one day occurs only on 
two or three occasions in a year. The blue colour of the 
sky is probably not so intense as in many parts of the 
temperate zone, while the brilliancy of the moon and stars is 
not perceptibly greater than on our clearest frosty nights, and 
is imdoubtedly much inferior to what is witnessed in many 
desert regions, and even in Southern Europe. 

On the whole, then, we must decide that uniformity and 
abundance, rather than any excessive manifestations, are the 
prevailing characteristic of all the climatal phenomena of the 
equatorial zone. 

Gonduding Bemarks 

We cannot better conclude our account of the equatorial 
climate than by quoting the following vivid description 
of the physical phenomena which occur during the early 
part of the dry season at Para. It is taken from Mr. Bates' 
Natwalist on the Amazons, and clearly exhibits some of 
the more characteristic features of a typical equatorial 
day. 

"At that early period of the day (the first two hours 
after sunrise) the sky was invariably cloudless, the thermometer 
marking 72° or 73° Fahr.; the heavy dew or the previous 
night's rain, which lay on the moist foliage, becoming quickly 
dissipated by the glowing sun, which, rising straight out of the 
east, mounted rapidly towards the zenith. All nature was 
fresh, new leaf and flower-buds expanding rapidly. . . . The 

1 On 10th January 1867, from 1 to 2 a.m. 



236 TROPICAL NATUEE 



heat increased hourly, and towards two o'clock reached 92° to 
93° Fahr., by which time every voice of bird and mammal 
was hushed. The leaves, which were so moist and fresh in 
early morning, now became lax and drooping, and flowers shed 
their petals. On most days in June and July a heavy shower 
would fall some time in the afternoon, producing a most 
welcome coolness. The approach of the rain-clouds was after 
a uniform fashion very interesting to observe. First, the cool 
sea-breeze which had commenced to blow about ten o'clock, 
and which had increased in force with the increasing power 
of the sun, would flag, and finally die away. The heat and 
electric tension of the atmosphere would then become almost 
insupportable. Languor and uneasiness would seize on every 
one, even the denizens of the forest betraying it by their 
motions. White clouds would appear in the east and gather 
into cumuli, with an increasing blackness along their lower 
portions. The whole eastern horizon would become almost 
suddenly black, and this would spread upwards, the sun at 
length becoming obscured. Then the rush of a mighty wind 
is heard through the forest, swaying the tree-tops j a vivid 
flash of lightning bursts forth, then a crash of thunder, and 
down streams the deluging rain. Such storms soon cease, 
leaving bluish-black motionless clouds in the sky until night. 
Meantime all nature is refreshed ; but heaps of flower-petals 
and fallen leaves are seen under the trees. Towards evening 
life revives again, and the ringing uproar is resumed from 
bush and tree. The following morning the sun again rises 
in a cloudless sky; and so the cycle is completed; spring, 
summer, and autumn, as it were in one tropical day. The 
days are more or less like this throughout the year. A 
little difference exists between the dry and wet seasons ; but 
generally the dry season, which lasts from July to December, 
is varied with showers, and the wet, from January to June, 
with sunny days. It results from this, that the periodical 
phenomena of plants and animals do not take place at about 
the same time in all species, or in the individuals of any given 
species, as they do in temperate countries. In Europe a 
woodland scene has its spring, its summer, its autumnal, and 
its winter aspects. In the equatorial forests the aspect is the 
same or nearly so every day in the year ; budding, flowering, 



I CLIMATE AND ASPECTS OP THE EQUATORIAL ZONE 237 

fniiting, and leaf-shedding are always going on in one species 
or other. It is never either spring, summer, or autumn, but 
each day is a combination of all three. With the day and 
night always of equal length, the atmospheric disturbances of 
each day neutralising themselves before each succeeding morn ; 
with the sun in its course proceeding midway across the sky, 
and the daily temperature almost the same throughout the 
year — ^how grand in its perfect equilibrium and simplicity is 
the march of Nature under the equator ! " 



II 



EQUATOEIAti VEGETATION 

The Equatorial Forest-Belt and its causes — General features of the Equa- 
torial Forests — Characteristics of the Larger Forest-trees — Flowering 
Trunks and their probable cause — Uses of Equatorial Forest-trees — • 
The Climbing Plants of the Equatorial Forests — Palms — Uses of Palm- 
trees and their Products — Ferns — Ginger-worts and wild Bananas — ■ 
Arums — Screw-pines — Orchids — Bamboos — Uses of the Bamboo — 
Mangroves — Sensitive-plants — Comparative Scarcity of Flowers — 
Concluding Remarks on Tropical Vegetation. 

In the following sketch of the characteristics of vegetable life 
in the equatorial zone, it is not intended to enter into any 
scientific details or to treat the subject in the slightest degree 
from a botanical point of view ; but merely to describe those 
general features of vegetation which are almost or quite 
peculiar to this region of the globe, and which are so general 
as to be characteristic of the greater part of it rather than of 
any particular country or continent within its limits. 

The Equatorial Forest-Belt and Us Ca/ases 

With but few and unimportant exceptions a great forest 
band from a thousand to fifteen hundred miles in width girdles 
the earth at the equator, clothing hill, plain, and mountain 
with an evergreen mantle. Lofty peaks and precipitous 
ridges are sometimes bare, but often the woody covering con- 
tinues to a height of eight or ten thousand feet, as in some of 
the volcanic mountains of Java and on portions of the Eastern 
Andes. Beyond the forests both to the north and south, we 
meet first with woody and then open country, soon changing 
into arid plains or even deserts which form an almost con- 



ti EQUATORIAL VEGETATION 239 

tinuous band in the vicinity of the two tropics. On the line 
of the tropic of Cancer we have, in America, the deserts and 
dry plains of New Mexico; in Africa the Sahara; and in 
Asia, the Arabian deserts, those of Beloochistan and Western 
India, and farther east the dry plains of North China and 
Mongolia. On the tropic of Capricorn we have, in America, 
the Grand Chaco desert and the Pampas; in Africa, the 
Kalahari desert and the dry plains north of the Limpopo ; 
while the deserts and waterless plains of Central Australia 
complete the arid zone. These great contrasts of verdure and 
barrenness occurring in parallel bands all round the globe, 
must evidently depend on the general laws which determine 
the distribution of moisture over the earth, more or less 
modified by local causes. "Without going into meteorological 
details, some of which have been given in the preceding 
chapter, the main facts may be explained by the mode in 
which the great aerial currents are distributed. The trade 
winds passing over the ocean from north-east to south-west, 
and from south-east to north-west, with an oblique tendency 
towards the equator, become saturated with vapour, and are 
ready to give out moisture whenever they are forced upwards 
or in any other way have their temperature lowered. The 
entire equatorial zone becomes thus charged with vapour- 
laden air, which is the primary necessity of a luxuriant 
vegetation. The surplus air (produced by the meeting of the 
two trade winds) which is ever rising in the equatorial belt 
and giving up its store of vapour, flows off north and south as 
dry, cool air, and descends to the earth in the vicinity of the 
tropics. Here it sucks up whatever moisture it meets with 
and thus tends to keep this zone in an arid condition. The 
trades themselves are believed to be supplied by descending 
currents from the temperate zones, and these are at first 
equally dry and only become vapour-laden when they have 
passed over some extent of moist surface. At the solstices 
the sun passes vertically over the vicinity of the tropics for 
several weeks, and this further aggravates the aridity ; and 
wherever the soil is sandy and there are no lofty mountain 
chains to supply ample irrigation, the result is a more or less 
perfect desert. Analogous causes, which a study of aerial 
currents will render intelligible, have produced other great 



240 TROPICAL NATURE 



forest-belts in the norttern and southern parts of the tem- 
perate zones ; but owing to the paucity of land in the 
southern hemisphere these are best seen in North America 
and Northern Euro-Asia, where they form the great northern 
forests of deciduous trees and of Coniferas. These being com- 
paratively well known to us, will form the standard by a 
reference to which we shall endeavour to point out and render 
intelligible the distinctive characteristics of the equatorial 
forest vegetation. 

General Featwes of the Eguatorial Forests 

It is not easy to fix upon the most distinctive features of 
these virgin forests, which nevertheless impress themselves 
upon the beholder as something quite unlike those of temper- 
ate lands, and as possessing a grandeur and sublimity altogether 
their own. Amid the countless modifications in detail which 
these forests present, we shall endeavour to point out the 
chief peculiarities as well as the more interesting phenomena 
which generally characterise them. 

The observer new to the scene would perhaps be first 
struck by the varied yet symmetrical trunks, which rise up 
with perfect straightness to a great height vrithout a branch, 
and which, being placed at a considerable average distance apart, 
give an impression similar to that produced by the columns 
of some enormous building. Overhead, at a height, perhaps, 
of a hundred and fifty feet, is an almost unbroken canopy of 
foliage formed by the meeting together of these great trees 
and their interlacing branches ; and this canopy is usually so 
dense that but an indistinct glimmer of the sky is to be seen, 
and even the intense tropical sunlight only penetrates to the 
ground subdued and broken up into scattered fragments. 
There is a weird gloom and a solemn silence, which combine 
to produce a sense of the vast — the primeval — almost of the 
infinite. It is a world in which man seems an intruder, and 
where he feels overwhelmed by the contemplation of the 
ever-acting forces which, from the simple elements of the 
atmosphere, bmld up the great mass of vegetation which 
overshadows and almost seems to oppress the earth. 



EQUATORIAL VEGETATION 241 



Characteristics of the Larger Forest Trees 

Passing from the general impression to the elements of 
which the scene is composed, the observer is struck by the 
great diversity of the details amid the general uniformity. 
Instead of endless repetitions of the same forms of tr\ink 
such as are to be seen in our pine, or oak, or beechwoods, 
the eye wanders from one tree to another and rarely detects 
two together of the same species. All are tall and upright 
columns, but they differ from each other more than do the 
columns of Gothic, Greek, and Egyptian temples. Some are 
almost cylindrical, rising up out of the ground as if their 
bases were concealed by accumulations of the soil ; others get 
much thicker near the ground like our spreading oaks ; others 
again, and these are very characteristic, send out towards the 
base flat and wing-Uke projections. These projections are 
thin slabs radiating from the main trunk, from which they 
stand out like the buttresses of a Gothic cathedral. They 
rise to various heighlis on the tree, from five or six to twenty 
or thirty feet ; they often divide as they approach the ground, 
and sometimes twist and curve along the surface for a con- 
siderable distance, forming elevated and greatly compressed 
roots. These buttresses are sometimes so large that the 
spaces between them if roofed over would form huts capable 
of containing several persons. Their use is evidently to give 
the tree an extended base, and so assist the subterranean 
roots in maintaining in an erect position so lofty a column 
crowned by a broad and massive head of branches and foliage. 
The buttressed trees belong to a variety of distinct groups. 
Thus, many of the Bombacese or sUk-cotton trees, several of 
the Leguminosae, and perhaps many trees belonging to other 
natural orders, possess these appendages. 

There is another form of tree, hardly less curious, in 
which the trunk, though generally straight and cylindrical, is 
deeply furrowed and indented, appearing as if made up of a 
number of small trees grown together at the centre. Some- 
times the junction of what seem to be the component parts 
is so imperfect that gaps or holes are left by which you can 
see through the trunk in various places. At first one is dis- 

B 



242 



TROPICAL NATURE 



posed to think this is caused by accident or decay, but re- 
peated examination shows it to be due to the natural growth 
of the tree. The accompanying outline sections of one of these 
trees that was cut down exhibits its character. It was a 
noble forest tree, more than two hundred feet high, but rather 
slender in proportion, and it was by no means an extreme ex- 
ample of its class. This peculiar form is probably produced 
by the downward growth of aerial roots, like some New 
Zealand trees whose growth has been traced, and of whose 
different stages drawings may be seen at the Library of the Lin- 
nsean Society. These commence their existence as parasitical 




Seutions or Tktjnk or a Boknean Fobest-Tbee. 
1. Section at seven feet from tlie ground. 2. 3. Sections much higher up. 



climbers, which take root in the fork of some forest tree and 
send down aerial roots which clasp round the stem that up- 
holds them. As these roots increase in size and grow 
together laterally they cause the death of their foster-parent. 
The climber then grows rapidly, sending out large branches 
above and spreading roots below, and as the supporting tree 
decays away the aerial roots grow together and form a new 
trunk, more or less furrowed and buttressed, but exhibiting 
no other marks of its exceptional origin. Aerial-rooted forest 
trees — like that figured in my Malay Archipelago (vol. i. p. 
131) — and the equally remarkable fig-trees of various species, 



n EQUATORIAL VEGETATION 243 

whose trunks are formed by a miniature forest of aerial roots, 
sometimes separate, sometimes matted together, are charac- 
teristic of the Eastern tropics, but appear to be rare or alto- 
gether unknown in America, and can therefore hardly be 
included among the general characteristics of the equatorial 
zone. 

Besides the varieties of form, however, the tree-trunks of 
these forests present many peculiarities of colour and texture. 
The majority are rather smooth -barked, and many are of 
peculiar whitish, green, yellowish, or brown colours, or occa- 
sionally nearly black. Some are perfectly smooth, others 
deeply cracked and furrowed, while in a considerable number 
the bark splits off in flakes or hangs down in long fibrous 
ribands. Spined or prickly trunks (except of pahns) are rare 
in the damp equatorial forests. Turning our gaze upwards 
from the stems to the foliage, we find two types of leaf not 
common in the temperate zone, although the great mass of 
the trees ofier nothing very remarkable in this respect. 
First, we have many trees with large, thick, and glossy leaves, 
like those of the cherry -laurel or the magnolia, but even 
larger, smoother, and more symmetrical. The leaves of the 
Asiatic caoutchouc tree (Ficus elastica), so often cultivated in 
houses, is a type of this class, which has a very fine efiect 
among the more ordinary-looking foliage. Contrasted with 
this is the fine pinnate foliage of some of the largest forest 
trees, which, seen far aloft against the sky, looks as delicate as 
that of the sensitive mimosa. 

Forest Trees of Low Growth 
The great trees we have hitherto been describing form, 
however, but a portion of the forest. Beneath their lofty 
canopy there often exists a second forest of moderate -sized 
trees, whose crowns, perhaps forty or fifty feet high, do not 
touch the lowermost branches of those above them. These 
are of course shade-loving trees, and their presence efiiectuaUy 
prevents the growth of any young trees of the larger kinds, 
until, overcome by age and storms, some monarch of the 
forest falls down, and, carrying destruction in its fall, opens 
up a considerable space into which sun and air can penetrate. 
Then comes a race for existence among the seedlings of the 



244 TROPICAL NATURE 



surrounding trees, in which a few ultimately prevail and fill 
up the space vacated by their predecessor. Yet beneath this 
second set of medium-sized forest trees there is often a third 
undergrowth of small trees, from six to ten feet high, of dwarf 
palms, of tree-ferns, and of gigantic herbaceous ferns. Yet 
lower, on the surface of the ground itself, we find much variety. 
Sometimes the earth is completely bare, a mass of decaying 
leaves and twigs and fallen fruts. More frequently it is 
covered with a dense carpet of selaginella or other lycopodi- 
acese, and these sometimes give place to a variety of herba- 
ceous plants, sometimes with pretty, but rarely with very 
conspicuous flowers. 

Flowering Trunks and their Probable Cause 

Among the minor but not unimportant peculiarities that 
characterise these lofty forests is the curious way in which 
many of the smaller trees have their flowers situated on the 
main trunk or larger branches instead of on the upper part 
of the tree. The cacao-tree is a well-known example of this 
peculiarity, which is not uncommon in tropical forests ; and 
some of the snialler trunks are occasionally almost hidden by 
the quantity of fruit produced on them. One of the most 
beautiful examples of this mode of flowering is a small tree 
of the genus Polyalthea, belonging to the family of the 
custard-apples, not uncommon in the forests of north-western 
Borneo. Its slender trunk, about fifteen or twenty feet high, 
was completely covered with star-shaped flowers, three inches 
across and of a rich orange-red colour, making the trees look 
as if they had been artificially decorated with brilliant gar- 
lands. The recent discoveries as to the important part played 
by msects in the fertilisation of flowers ofi'ers a very probable 
explanation of this peculiarity. Bees and butterflies are the 
greatest flower -haunters. The former love the sun and fre- 
quent open grounds or the flowery tops of the lofty forest 
trees fully exposed to the sun and air. The forest shades are 
frequented by thousands of butterflies, but these mostly keep 
near the ground, where they have a free passage among the 
tree-trunks and visit the flowering shrubs and herbaceous 
plants. To attract these it is necessary that flowers should 
be low down and conspicuous. If they grew in the usual 



II EQUATORIAL VEGETATION 245 

way on the tops of these smaller trees overshadowed by the 
dense canopy above them they would be out of sight of both 
groups of insects ; but being placed openly on the stems, and 
in the greatest profusion, they cannot fail to attract the atten- 
tion of the wandering butterflies. 

Uses of Equatorial Forest Trees 

Amid this immense variety of trees, the natives have found 
out such as are best adapted to certain purposes. The wood 
of some is light and soft, and is used for floats or for carving 
rude images, stools, and ornaments for boats and houses. The 
flat slabs of the buttresses are often used to make paddles. 
Some of the trees with furrowed stems are exceedingly strong 
and durable, serving as posts for houses or as piles on which 
the water -villages are built. Canoes, formed from a trunk 
hollowed out and spread open under the action of heat require 
one kind of wood, those built up with planks another ; and as 
the species of trees in these forests are so much more numer- 
ous than the wants of a semi-civilised population, there are 
probably a large number of kinds of timber which vrill some 
day be found to be well adapted to the special requirements 
of the arts and sciences. The products of the trees of the 
equatorial forests, notwithstanding our imperfect knowledge 
of them, are already more useful to civilised man than to the 
indigenous inhabitants. To mention only a few of those whose 
names are tolerably familiar to us, we have such valuable 
woods as mahogany, teak, ebony, lignum-vitse, purple -heart, 
iron-wood, sandal-wood, and satin-wood ; such useful gums as 
india-rubber, gutta-percha, tragacanth, copal, lac, and dammar ; 
such dyes as are yielded by log-wood, brazil-wood, and sappan- 
wood ; such drugs as the balsams of Capivi and Tolu, camphor, 
benzoin, catechu or terra-japonica, cajuput oil, gamboge, quin- 
ine, Angostura bark, quassia, and the urari and upas poisons ; 
of spices we have cloves, cinnamon, and nutmegs ; and of 
fruits, brazil-nuts, tamarinds, guavas, and the valuable cacao ; 
while residents in our tropical colonies enjoy the bread-fruit, 
avocado-pear, custard-apple, durian, mango, mangosteen, sour- 
sop, papaw, and many others. This list of useful products 
from the exogenous trees alone of the equatorial forests, 
excluding those from the palms, shrubs, herbs, and creepers. 



246 TROPICAL NATURE 



might have been multiplied many times over by the introduc- 
tion of articles whose names would be known only to those 
interested in special arts or sciences ; but imperfect as it is, it 
will serve to aflford a notion of the value of this vast treasure- 
house, which is as yet but very partially explored. 

The Climbing Plants of the Equatorial Forests 
Next to the trees themselves the most conspicuous and 
remarkable feature of the tropical forests is the profusion of 
woody creepers and climbers that everywhere meet the eye. 
They twist around the slenderer stems, they drop down 
pendent from the branches, they stretch tightly from tree 
to tree, they hang looped in huge festoons from bough to 
bough, they twist in great serpentine coils or lie in entangled 
masses on the ground. Some are slender, smooth, and root- 
like ; others are rugged or knotted ; often they are twined 
together into veritable cables ; some are flat like ribands, 
others are curiously waved and indented. Where they spring 
from or how they grow is at first a complete puzzle. They 
pass overhead from tree to tree, they stretch in tight cordage 
like the rigging of a ship from the top of one tree to the base 
of another, and the upper regions of the forest often seem 
full of them without our being able to detect any earth- 
growing stem from which they arise. The conclusion is at 
length forced upon us that these woody climbers must possess 
the two qualities of very long life and almost indefinite longi- 
tudinal growth, for by these suppositions alone can we explain 
their characteristic features. The growth of climbers, even, 
more than all other plants, is upward towards the light. In 
the shade of the forest they rarely or never flower, and seldom 
even produce foliage, but when they have reached the summit 
of the tree that supports them, they expand under the genial 
influence of light and air, and often cover their foster-parent 
with blossoms not its own. Here, as a rule, the climber's 
growth would cease ; but the time comes when the supporting 
tree rots and falls, and the creeper comes with it in torn and 
tangled masses to the ground. But though its foster-parent 
is dead it has itself received no permanent injury, but shoots 
out again till it finds a fresh support, mounts another tree, 
and again puts forth its leaves and flowers. In time the old 



n EQUATORIAL VEGETATION 247 

tree rots entirely away and the creeper remains tangled on 
the ground. Sometimes branches only fall and carry a por- 
tion of the creeper tightly stretched to an adjoining tree ; at 
other times the whole tree is arrested by a neighbour, to 
which the creeper soon transfers itself in order to reach the 
upper Ught. When by the fall of a branch the creepers are 
left hanging in the air, they may be blown about by the 
wind and catch hold of trees growing lip beneath them, and 
thus become festooned from one tree to another. When 
these accidents and changes have been again and again 
repeated the climber may have travelled very far from its 
parent stem, and may have mounted to the tree tops and 
descended again to the earth several times over. Only in 
this way does it seem possible to explain the wonderfully 
complex manner in which these climbing plants wander up 
and down the forest as if guided by the strangest caprices, or 
how they become so crossed and tangled together in the 
wildest confusion. 

The variety in the length, thickness, strength, and tough- 
ness of these climbers enables the natives of tropical countries 
to put them to various uses. Almost every kmd of cordage 
is supplied by them. Some wiU stand iu water without rot- 
ting, and are used for cables, for lines to which are attached 
fish-traps, and to bind and strengthen the wooden anchors 
used generally in the East. Boats and even large saiHng 
vessels are built, whose planks are entirely fastened together 
by this ktad of cordage skilfully applied to internal ribs. For 
the better kinds of houses, smooth and uniform varieties are 
chosen, so that the beams and rafters can be bound together 
with neatness, strength, and uniformity, as is especially observ- 
able among the indigenes of the Amazonian forests. When 
baskets of great strength are required special kinds of creepers 
are used ; and to serve ahnost every purpose for which we 
should need a rope or a chain, the tropical savage adopts some 
one of the numerous forest-ropes which long experience has 
shown to have qualities best adapted for it. Some are smooth 
and supple ; some are tough and wiU bear twisting or tying ; 
some wiU last longest in salt water, others in fresh ; one is 
uninjured by the heat and smoke of fires, while another is 
bitter or otherwise prejudicial to insect enemies. 



248 TROPICAL NATURE 



Besides these various kinds of trees and climbers, which 
form the great mass of the equatorial forests and determine 
their general aspect, there are a number of forms of plants 
which are always more or less present, though in some parts 
scarce and in others in great profusion, and which largely aid 
in giving a special character to tropical as distinguished from 
temperate vegetation. Such are the various groups of palms, 
ferns, ginger-worts, and wild plantains, arums, orchids, and 
bamboos ; and under these heads we shall give a short account 
of the part they take in giving a distinctive aspect to the 
equatorial forests. 

Palms 

Although these are found throughout the tropics, and a 
few species even extend into the warmer parts of the tem- 
perate regions, they are yet so much more abundant and 
varied within the limits of the region we are discussing that 
they may be considered as among the most characteristic 
forms of vegetation of the equatorial zone. They are, how- 
ever, by no means generally present, and we may pass 
through miles of forest without even seeing a palm. In other 
parts they abound ; either forming a lower growth in the 
lofty forest, or in swamps and on hillsides sometimes rising 
up above the other trees. On river-banks they are especially 
conspicuous and elegant, bending gracefully over the stream, 
their fine foliage waving in the breeze, and their stems often 
draped with hanging creepers. 

The chief feature of the palm tribe consists in the 
cylindrical trunk crowned by a mass of large and somewhat 
rigid leaves. They vary in height from a few feet to that of 
the' loftiest forest trees. Some are stemless, consisting only 
of a spreading crown of large pinnate leaves ; but the great 
majority have a trunk slender in proportion to its height. 
Some of the smaller species have stems no thicker than 
a lead pencil, and foiu- or five feet high ; while the great 
Mauritia of the Amazon has a trunk full two feet in dia- 
meter, and more than one hundred feet high. Some 
species probably reach a height of two hundred feet, for 
Humboldt states that in South America he measured a 
palm, which was one hundred and ninety-two English feet 



II EQUATORIAL VEGETATION 249 

high. The leaves of palms are often of immense size. 
Those of the Manicaria saccifera of Para are thirty feet long 
and four or five feet wide, and are not pinnate but entire 
and very rigid. Some of the pinnate leaves are much larger, 
those of the Eaphia tsedigera and Maximiliana regia being 
both sometimes more than fifty feet long. The fan-shaped 
leaves of other species are ten or twelve feet in diameter. 
The trunks of palms are sometimes smooth and more or less 
regularly ringed, but they are frequently armed with dense 
prickles which are sometimes eight inches long. In some 
species the leaves fall to the ground as they decay, leaving a 
clean scar, but in most cases they are persistent, rotting 
slowly away, and leaving a mass of fibrous stumps attached 
to the upper part of the stem. This rotting mass forms an 
excellent soil for ferns, orchids, and other semi -parasitical 
plants, which form an attractive feature on what would 
otherwise be an unsightly object. The sheathing margins of 
the leaves often break up into a fibrous material, sometimes 
resembling a coarse cloth, and in other cases more like horse- 
hair. The fiowers are not individually large, but form large 
spikes or racemes, and the fruits are often beautifully scaled 
and hang in huge bunches, which are sometimes more than a 
load for a strong man. The climbing palms are very remark- 
able, their tough, slender, prickly stems mounting up by means 
of the hooked midribs of the leaves to the tops of the 
loftiest forest trees, above which they send up an elegant 
spike of foliage and flowers. The most important are the 
American Desmoncus and the Eastern Calamus, the latter 
being the well-known rattan or cane of which chair-seats are 
made, from the Malay name " rotang." The rattan-pahns 
are the largest and most remarkable of the climbing group. 
They are very abundant in the drier equatorial forests, and 
more than sixty species are known from the Malay Archi- 
pelago. The stems (when cleaned from the sheathing leaves 
and prickles) vary in size, from the thickness of a quill to 
that of the wrist; and where abundant they render the 
forest almost impassable. They lie about the ground coiled 
and twisted and looped in the most fantastic manner. They 
hang in festoons from trees and branches, they rise suddenly 
through mid air up to the top of the forest, or coil loosely 



250 TROPICAL NATURE 



over shrubs and in thickets like endless serpents. They must 
attain an immense age, and apparently have almost unlimited 
powers of growth, for some are said to have been found 
which were six hundred or even one thousand feet long, and 
if so they are probably the longest of all vegetable growths. 
The mode in which such great lengths and tangled convolu- 
tions have been attained has already been explained in the 
general account of woody climbers. From the immense 
strength of these canes and the facility with which they can 
be split, they are universally used for cordage in the countries 
where they grow in preference to any other climbers, and 
immense quantities are annually exported to all parts of the 
world. 

Uses of Palm-trees and their Products 

To the natives of the equatorial zone the uses of palms 
are both great and various. The fruits of several species 
— more especially the cocoa-nut of the East and the peach- 
nut (Guilielma speciosa) of America — furnish abundance of 
wholesome food, and the whole interior of the trunk of the 
sago palm is converted into an edible starch — our sago. 
Many other palm -fruits yield a thin pulp, too small in 
quantity to be directly eaten, but which, when rubbed oiT 
and mixed with a proper quantity of water, forms an exceed- 
ingly nutritious and agreeable article of food. The most 
celebrated of these is the assai of the Amazon, made from the 
fruit of Euterpe oleracea, and which, as a refreshing, nourish- 
ing, and slightly stimulating beverage for a tropical country, 
takes the place of our chocolate and coffee. A number of 
other palms yield a similar product, and many that are not 
eaten by man are greedily devoured by a variety of animals, 
so that the amount of food produced by this tribe of plants 
is much larger than is generally supposed. 

The sap which pours out of the cut flower-stalk of several 
species of palm, when slightly fermented, forms palm-wine or 
toddy, a very agreeable drink ; and when mixed with various 
bitter herbs or roots which check fermentation, a fair imita- 
tion of beer is produced. If the same fluid is at once boiled 
and evaporated it produces a quantity of excellent sugar. 
The Arenga saccharifera, or sugar-palm of the Malay coun- 
tries, is perhaps the most productive of sugar. A single tree 



11 EQUATORIAL VEGETATION 251 

will continue to pour out several quarts of sap daily for 
weeks together, and where the trees are abundant this forms 
the chief drink and most esteemed luxury of the natives. A 
Dutch chemist, Mr. De Vry, who has studied the subject in 
Java, believes that great advantages would accrue from the 
cultivation of this tree in place of the sugar-cane. According 
to his experiments it would produce an equal quantity of 
sugar of good quality with far less labour and expense, be- 
cause no manure and no cultivation would be required, and 
the land will never be impoverished, as it so rapidly becomes 
by the growth of sugar-cane. The reason of this difference 
is, that the whole produce of a cane -field is taken off the 
ground, the crushed canes being burnt; and the soil thus 
becomes exhausted of the various salts and minerals which 
form part of the woody fibre and foliage. These must be 
restored by the application of manure, and this, together 
with the planting, weeding, and necessary cultivation, is very 
expensive. With the sugar-palm, however, nothing whatever 
is taken away but the juice itself ; the foliage falls on the 
ground and rots, giving back to it what it had taken ; and 
the water and sugar in the juice being almost wholly derived 
from the carbonic acid and aqueous vapour of the atmos- 
phere, there is no impoverishment ; and a plantation of these 
palms may be kept up on the same ground for an indefinite 
period. Another most important consideration is, that these 
trees will grow on poor rocky soil and on the steep slopes of 
ravines and hillsides, where any ordinary cultivation is im- 
possible, and a great extent of fertile land would thus be set 
free for other purposes. Yet further, the labour required for 
such sugar plantations as these would be of a light and inter- 
mittent kind, exactly suited to a semi - civilised people, to 
whom severe and long-continued labour is never congenial. 
This combination of advantages appears to be so great that it 
seems possible that the sugar of the world may in the future 
be produced from what would otherwise be almost waste 
ground ; and it is to be hoped that the experiment will soon 
be tried in some of our tropical colonies, more especially as 
an Indian palm. Phoenix sylvestris, also produces abundance 
of sugar, and might be tried in its native country. 

Other articles of food produced from palms are, cooking- 



252 TROPICAL NATURE 



oil from the cocoa-nut and baccaba palm, salt from the fruit 
of a South American palm (Leopoldinia major), while the 
terminal bud or " cabbage " of many species is an excellent 
and nutritious vegetable ; so that palms may be said to supply 
bread, oil, sugar, salt, fruit, and vegetables. Oils for various 
other purposes are made from several distinct palms, especially 
from the celebrated oil palm of West Africa, while wax is 
secreted from the leaves of some South American species ; 
the resin called Dragon's blood is the product of one of the 
rattan palms. The fruit of the Areca palm is the " betel-nut " 
so universally chewed by the Malays as a gentle stimulant, 
and is their substitute for the opium of the Chinese, the 
tobacco of Europeans, and the coca-leaf of South America. 

For thatching purposes the leaves of palms are invaluable, 
and are universally used wherever they are abundant ; and 
the petioles or leaf stalks, often fifteen or twenty feet long, 
are used as rafters, or when fastened together with pegs form 
doors, shutters, partitions, or even the walls of entire houses. 
They are wonderfully light and strong, being formed of a 
dense pith covered with a hard rind or bark, and when split 
up and pegged together serve to make many kinds of boxes, 
which, when covered with the broad leaves of a species of screw- 
pine and painted or stained of various colours, are very strong 
and serviceable as well as very ornamental. Eopes and cables 
are woven from the black fibrous matter that fringes the 
leaves of the sugar-palm and some other species, while fine 
strings of excellent quality, used even for bow-strings, fishing- 
lines, and hammocks, are made of fibres obtained from the 
unopened leaves of some American species. The fibrous 
sheath at the base of the leaves of the cocoa-nut palm is so 
compact and cloth-like that it is used for a variety of purposes, 
as for strainers, for wrappers, and to make very good hats. 
The great woody spathes of the larger palms serve as natural 
baskets, as cradles, or even as cooking-vessels in which water 
may be safely boiled. The trunks form excellent posts and 
fencing, and when split make good flooring. Some species 
are used for bows, others for blow-pipes ; the smaller palm- 
spines are sometimes used as needles or to make fish-hooks, 
and the larger as arrows. To describe in detail all the uses 
to which palm-trees and their products are applied in various 



n EQUATORIAL VEGETATION 253 

parts of the world might occupy a volume ; but the preceding 
sketch will serve to give an idea of how important a part is 
filled by this noble family of plants, whether we regard them 
as a portion of the beautiful vegetation of the tropics, or in 
relation to the manners and customs, the lives and the well- 
being, of the indigenous inhabitants. 

Ferns 

The type of plants which, next to palms, most attracts 
attention in the equatorial zone is perhaps that of the 
ferns, which here display themselves in vast profusion and 
variety. They grow abundantly on rocks and on decaying 
trees; they clothe the sides of ravines and the margins of 
streams ; they climb up the trees and over bushes ; they form 
tufts and hanging festoons among the highest branches. 
Some are as small as mosses, others have huge fronds eight or 
ten feet long, while in mountainous districts the most elegant 
of the group, the tree-ferns, bear their graceful crowns on 
slender stems twenty to thirty, or even fifty feet high. It is 
this immense variety rather than any special features that 
characterises the fern -vegetation of the tropics. We have 
here almost every conceivable modification of size, form of 
fronds, position of spores, and habit of growth, in plants that 
still remain unmistakably ferns. Many climb over shrubs 
and bushes in a most elegant manner; others cling closely 
to the bark of trees like ivy. The great birds'-nest fern 
(Platycerium) attaches its shell-like fronds high up on the 
trunks of lofty trees. Many small terrestrial species have 
digitate, or ovate, or ivy -shaped, or even whorled fronds, 
resembling at first sight those of some herbaceous flowering 
plants. Their numbers may be judged from the fact that in 
the vicinity of Tarrapoto, in Peru, Dr. Spruce gathered two 
hundred and fifty species of ferns, while the single volcanic 
mountains of Pangerango in Java (ten thousand feet high) is 
said to have produced three hundred species. 

Ginger-worts and wild Bananas 

These plants, forming the families Zingiberacese and 
Musacese of botanists, are very conspicuous ornaments of the 
equatorial forests, on account of their large size, fine foliage. 



254 TROPICAL NATURE 



and handsome flowers. The bananas and plantains are well 
known as among the most luxuriant and beautiful productions 
of the tropics. Many species occur wild in the forests ; all 
have majestic foliage and handsome flowers, while some pro- 
duce edible fruit. Of the ginger-worts (Zingiberacese and 
Marantacese), the well-known cannas of our sub -tropical 
gardens may be taken as representatives, but the equatorial 
species are very numerous and varied, often forming dense 
thickets in damp places, and adorning the forest shades with 
their elegant and curious or showy flowers. The maranths 
produce "arrowroot," while the ginger-worts are highly 
aromatic, producing ginger, cardamums, grains of paradise, 
turmeric, and several medicinal drugs. The Musacese pro- 
duce the most valuable of tropical fruits and foods. The 
banana is the variety which is always eaten as a fruit, having 
a delicate aromatic flavour ; the plantain is a larger variety, 
which is best cooked. Eoasted in the green state it is an 
excellent vegetable, resembling roasted chestnuts ; when ripe 
it is sometimes pulped and boiled with water, making a very 
agreeable sweet soup ; or it is roasted, or cut into slices and 
fried, in either form being a delicious tropical substitute for 
fruit pudding. These plants are annuals, producing one im- 
mense bunch of fruit. This bunch is sometimes four or five feet 
long, containing near two hundred plantains, and often weighs 
about a hundredweight. They grow very close together, and 
Humboldt calculated that an acre of plantains would supply 
more food than could be obtained from the same extent of 
ground by any other known plant. Well may it be said that 
the plantain is the glory of the tropics, and well was the 
species named by Linnseus — Musa paradisiaca ! 

Arums 

Another very characteristic and remarkable group of 
tropical plants are the epiphytal and climbing arums. 
These are known by their large, arrow-shaped, dark green 
and glossy leaves, often curiously lobed or incised, and 
sometimes reticulated with large open spaces, as if pieces had 
been regularly eaten out of them by some voracious insects. 
Sometimes they form clusters of foliage on living or dead 
trees, to which they cling by their aerial roots. Others climb 



II EQUATORIAL VEGETATION 255 

up the smooth bark of large trees, sending out roots as they 
ascend which clasp around the trunk. Some mount straight 
up, others wind round the supporting trunks, and their large, 
handsome, and often highly remarkable leaves, which spread 
out profusely all along the stem, render them one of the most 
striking forms of vegetation which adorn the damper and more 
luxuriant parts of the tropical forests of both hemispheres. 

Screvi-pines 

These singular plants, constituting the family Pandanaceae 
of botanists, are very abundant in many parts of the Eastern 
tropics, while they are comparatively scarce in America. 
They somewhat resemble Yuccas, but have larger leaves, 
which grow in a close spiral screw on the stem. Some are 
large and palm-like, and it is a curious sight to stand under 
these and look up at the huge vegetable screw formed by 
the bases of the long, drooping leaves. Some have slender 
branched trunks, which send out aerial roots; others are 
stemless, consisting of an immense- spiral cluster of stiff leaves 
ten or twelve feet long and only two or three inches wide. 
They abound most in sandy islands, while the larger species 
grow in swampy forests. Their large-clustered fruits, some- 
thing Hke pine-apples, are often of a red colour ; and their 
long, stiff leaves are of great use for covering boxes and for 
many other domestic uses. 

Orchids 

These interesting plants, so well known from the ardour 
with which they are cidtivated on account of their beautiful 
and singular flowers, are pre-eminently tropical, and are 
probably more abundant in the moimtains of the equatorial 
zone than in any other region. Here they are almost omni- 
present in some of their countless forms. They grow on the 
stems, in the forks or on the branches of trees ; they abound 
on fallen trunks ; they spread over rocks, or hang down the 
face of precipices ; while some, Hke our northern species, 
grow on the ground among grass and herbage. Some trees 
whose bark is especially well adapted for their support are 
crowded with them, and these form natural orchid-gardens. 
Some orchids are particularly fond of the decaying leaf-stalks 



256 TROPICAL NATURE 



of palms or of tree-ferns. Some grow best over water, others 
must be elevated on lofty trees and well exposed to sun and 
air. The wonderful variety in the form, structure, and colour 
of the flowers of orchids is well known ; but even our finest 
collections give an inadequate idea of the numbers of these 
plants that exist in the tropics, because a large proportion of 
them have quite inconspicuous flowers and are not worth 
cultivation. More than thirty years ago the number of known 
orchids was estimated by Dr. Lindley at three thousand species, 
in Bentham and Hooker's Genera Plantarwm at five thousand, 
and it is not improbable that they may be now nearly six 
thousand. But whatever may be the numbers of the collected 
and described orchids, those that still remain to be discovered 
must be enormous. Unlike ferns, the species have a very 
limited range, and it would require the systematic work of a 
good botanical collector during several years to exhaust any 
productive district — say such an island as Java — of its orchids. 
It is not therefore at all improbable that this remarkable 
group may ultimately prove to be the most numerous in 
species of all the families of flowering plants. 

Although there is a peculiarity of habit that enables one 
soon to detect an orchidaceous plant even when not in flower, 
yet they vary greatly in size and aspect. Some of the small 
creeping species are hardly larger than mosses, while the larger 
Grammatophyllums of Borneo, which grow in the forks of trees, 
form a mass of leafy stems ten feet long, and some of the 
terrestrial species — as the American Sobralias — grow erect to 
an equal height. The fleshy aerial roots of most species give 
them a very peculiar aspect, as they often grow to a great 
length in the open air, spread over the surface of rocks, or 
attach themselves loosely to the bark of trees, extracting 
nourishment from the rain and from the aqueous vapour of 
the atmosphere. Yet notwithstanding the abundance and 
variety of orchids in the equatorial forests, they seldom 
produce much effect by their flowers. This is due partly to 
the very large proportion of the species having quite incon- 
spicuous flowers ; and partly to the fact that the flowering 
season for each kind lasts but a few weeks, while different 
species flower almost every month in the year. It is also 
due to the manner of growth of orchids, generally in single 



11 EQUATORIAL VEGETATION 257 

plants or clumps, whicli are seldom large or conspicuous 
as compared with the great mass of vegetation around them. 
It is only at long intervals that the traveller meets with any- 
thing which recalls the splendour of our orchid-houses and 
flower shows. The slender-stalked golden Oncidiums of the 
flooded forests of the Upper Amazon ; the grand Cattleyas of 
the drier forests ; the Cselogynes of the swamps, and the re- 
markable Vanda lowii of the hill forests of Borneo, — are the 
chief examples of orchid beauty that have impressed them- 
selves on the memory of the present writer during twelve 
years' wandering in tropical forests. The last-named plant is 
unique among orchids, its comparatively smaU cluster of leaves 
sending out numerous flower-stems, which hang down like 
cords to a length of eight feet, and are covered with numbers 
of large star-like crimson-spotted flowers. 

Bamboos 

The gigantic grasses called bamboos can hardly be classed 
as typical plants of the tropical zone, because they appear to 
be rare in the entire African continent and are comparatively 
scarce in South America. They also extend beyond the 
geographical tropics in China and Japan as well as in Northern 
India. It is, however, within the tropics and towards the 
equator that they attain their full size and beauty, and it is 
here that the species are most numerous and offer that variety 
of form, size, and quality which renders them so admirable a 
boon to man. A fine clump of large bamboos is perhaps the 
most graceful of all vegetable forms, resembling the light and 
airy plumes of the bird of paradise copied on a gigantic scale 
in living foliage. Such clumps are often eighty or a hundred 
feet high, the glossy stems, perhaps six inches thick at the 
base, springing up at first straight as an arrow, tapering 
gradually to a slender point, and bending over in elegant 
curves with the weight of the slender branches and grassy 
leaves. The various species differ greatly in size and propor- 
tions, in the comparative length of the joints, in the thickness 
and strength of the stem-walls, in their straightness, smooth- 
ness, hardness, and durability. Some are spiny, others are 
unarmed ; some have simple stems, others are thickly set with 
branches ; while some species even grow in such an irregular, 



258 TROPICAL NATURE 



zigzag, branched manner as to form veritable climbing bam- 
boos. They generally prefer dry and upland stations, though 
some grow near the banks of rivers, and a few in the thick 
forests, and, in South America, in flooded tracts. They often 
form dense thickets where the forests have been cleared away, 
and owing to their great utility they are cultivated or pre- 
served near native houses and villages, and in such situations 
often give a finishing charm to the landscape. 

Uses of the Bamboo 

Perhaps more than any other single type of vegetation, the 
bamboo seems specially adapted for the use of half-civilised 
man in a wild tropical country ; and the purposes to which it 
is applied are almost endless. It is a natural column or 
cylinder, very straight, uniform in thickness, of a compact and 
solid texture, and with a smooth, flinty, naturally-polished, 
external skin. It is divided into ringed joints at regular 
intervals which correspond to septa or partitions within, so 
that each joint forms a perfectly closed and water-tight vessel. 
Owing to its hoUowness, the hardness of the external skin, 
and the existence of the joints and partitions, it is wonder- 
fully strong in proportion to its weight. It can be found of 
many distinct sizes and proportions, light or heavy, long or 
short-jointed, and varying from the size of a reed to that of a 
tall and slender palm-tree. It can be split with great facility 
and accuracy, and, owing to its being hollow, it can be easily 
cut across or notched with a sharp knife or hatchet. It is 
excessively strong and highly elastic, and whether green or 
dry is almost entirely free from any peculiar taste or smell. 
The way in which these various qualities of the bamboo 
render it so valuable will be best shown by giving a brief 
account of some of the uses to which it is applied in the 
Malay Archipelago. 

Several effective weapons are easily made from bamboo. 
By cutting off the end very obliquely just beyond a joint, a 
very sharp cutting point is produced suitable for a spear, 
dagger, or arrow-head, and capable of penetrating an animal's 
body as readily as iron. Such spears are constantly used by 
many of the Malay tribes. In the eastern half of the Archi- 
pelago, where bows and arrows are used, these weapons are 



II EQUATORIAL VEGETATION 259 

often formed entirely of bamboo. The harder and thicker 
sorts, split and formed with tapering ends, make a very 
strong and elastic bow, while a narrow strip of the outer sMn 
of the same is used for the string, and the slender reed-like 
kinds make excellent arrows. One of the few agricultural 
tools used by the Papuans — a spud or hoe for planting or 
weeding — is made of a stout bamboo cut somewhat Kke the 
spear. 

For various domestic purposes the uses of bamboo are 
endless. Ladders are rapidly made from two bamboo poles 
of the required length, by cutting small notches just above 
each ring, forming holes to receive the rungs or steps formed 
of a slenderer bamboo. For climbing lofty trees to get bees- 
wax, a temporary ladder reaching to any height is ingeniously 
formed of bamboo. One of the hardest and thickest sorts is 
chosen, and from this a number of pegs about a foot long are 
made. These are sharpened at one end and then driven into 
the tree in a vertical line about three feet apart. A tall and 
slender bamboo is then placed upright on the ground and 
securely tied with rattan or other cords to the heads of these 
pegs, which thus with the tree itself form a ladder. A man 
mounts these steps and builds up the ladder as he goes, 
driving in fresh pegs and splicing on fresh bamboos till he 
reaches the lower branches of the tree, which is sometimes 
eighty or a hundred feet from the ground. As the weight of 
the climber is thrown on several of the pegs which are bound 
together and supported by the upright bamboo, this ladder is 
much safer than it looks at first sight, and it is made with 
wonderful rapidity. When a path goes up a steep hill over 
smooth ground, bamboo steps are often laid down to prevent 
slipping while carrying heavy loads. These are made with 
uniform lengths of stout bamboo in which opposite notches 
are cut at each end just within a joint. These notches allow 
strong bamboo pegs to be driven through into the ground, 
thus keeping the steps securely in place. The masts and 
yards of native vessels are almost always formed of bamboo, 
as it combines lightness, strength, and elasticity in an 
unequalled degree. Two or three large bamboos also form 
the best outriggers to canoes on account of their great buoy- 
ancy. They also serve to form rafts; and in the city of 



260 TROPICAL NATURE 



Palembang, in Sumatra, there is a complete street of floating 
houses supported on rafts formed of huge bundles of bamboos. 
Bridges across streams or to carry footpaths along the face of 
precipices are constructed by the Dyaks of Borneo whoUy of 
bamboos, and some of these are very ingeniously hung from 
overhanging trees by diagonal rods of bamboo, so as to form 
true suspension bridges. The flooring of Malay houses is 
almost always of bamboo, but is constructed in a variety, of 
ways. Generally large bamboos are used, split lengthways 
twice and the pieces tied down with rattan. This forms a 
grated floor, slightly elastic, and very pleasant to the bare- 
footed natives. A superior floor is sometimes formed of slabs, 
which are made from very stout bamboos cut into lengths of 
about three or four feet and split down one side. The joints 
are then deeply and closely notched all round with a sharp 
chopping-knife, so that the piece can be unrolled as it were 
and pressed flat, when it forms a hard board with a natural 
surface, which, with a little wear, becomes beautifully smooth 
and polished. Blinds, screens, and mats are formed of bam- 
boos in a variety of ways, — sometimes of thin kinds crushed 
flat and plaited, but more frequently of narrow strips con- 
nected together with cords of bamboo-bark or rattan. Strips 
of bamboo supported on cross-pieces form an excellent bed, 
which from its elasticity supplies the purpose of a mattress as 
well, and only requires a mat laid over it to insure a comfort- 
able night's repose. Every kind of basket, too, is made of 
bamboo,' from the coarsest heavy kinds to such as are fine and 
ornamental. In such countries as Lombock and Macassar, 
where the land is much cultivated and timber scarce, entire 
houses are built of bamboo, — posts, walls, floors, and roofs all 
being constructed of this one material; and perhaps in no 
other way can so elegant and well-finished a house be built so 
quickly and so cheaply. Almost every kind of furniture is 
also made of the same material, excellent bamboo chairs, sofas, 
and bedsteads being made in the Moluccas, which, for appear- 
ance, combined with cheapness, are probably unsurpassed in 
the world. A chair costs sixpence, and a sofa two shillings. 

Among simpler uses bamboos are admirably adapted for 
water-vessels. Some of the lighter sorts are cut into lengths 
of about five feet, a small hole being knocked through the 



II EQUATORIAL VEGETATION 261 

septa of the joints. This prevents the water from running 
out too quickly, and facilitates its being poured out in a 
regulated stream to the last drop. Three or four of these 
water-vessels are tied together and carried on the back, and 
they stand very conveniently in a corner of the hut. Water- 
pipes and aqueducts are also readily made from bamboo tubes 
supported at intervals on two smaller pieces tied crosswise. 
In this way a stream of water is often conveyed from some 
distance to the middle of a village. Measures for rice or 
palm-wine, drinking-vessels, and water-dippers, are to be found 
almost ready-made in a joint of bamboo; and when fitted 
with a cap or lid they form tobacco or tinder-boxes. Perches 
for parrots, with food and water vessels, are easily made out 
of a single piece of bamboo, while with a little more labour 
elegant bird-cages are constructed. In Timor a musical 
instrument is formed from a single joint of a large bamboo 
by carefully raising seven strips of the hard skin to form 
strings, which remain attached at both ends and are elevated 
by small pegs wedged underneath, the strings being prevented 
from splitting off by a strongly-plaited ring of a similar mate- 
rial bound round each end. An opening cut on one side 
allows the bamboo to vibrate in musical notes when the harp- 
like strings are sharply puUed with the fingers. In Java 
strips of bamboo supported on stretched strings and struck 
with a small stick produce the higher notes in the "game- 
lung " or native band, which consists mainly of sets of gongs 
and metallic plates of various sizes. Almost all the common 
Chinese paper is made from the foliage and stems of some 
species of bamboo, while the young shoots, as they first spring 
out of the ground, are an excellent vegetable, quite equal to 
artichokes. Single joints of bamboo make excellent cooking- 
vessels while on a journey. Rice can be boiled in them to 
perfection, as well as fish and vegetables. They serve too for 
jars in which to preserve sugar, salt, fruit, molasses, and 
cooked provisions ; and for the smoker, excellent pipes and 
hookahs can be formed in a few minutes out of properly 
chosen joints of bamboo. 

These are only a sample of the endless purposes to which 
the bamboo is applied in the countries of which it is a 
native, its chief characteristic being that in a few minutes it 



262 TROPICAL NATURE 



can be put to uses which, if ordinary wood were used, would 
require hours or even days of labour. There is also a regu- 
larity and a finish about it which is found in hardly any other 
woody plant; and its smooth and symmetrically ringed 
surface gives an appearance of fitness and beauty to its 
varied applications. On the whole, we may perhaps consider 
it as the greatest boon which nature gives to the natives of 
the eastern tropics. 

Mangroves 

Among the forms of plants which are sure to attract 
attention in the tropics are the mangroves, which grow 
between tide-marks on coasts and estuaries. These are low 
trees with widely-spreading branches and a network of aerial 
roots a few feet above the ground ; but their most remarkable 
peculiarity is, that their fruits germinate on the tree, sending 
out roots and branches before falling into the muddy soil — 
a completely formed plant. In some cases the root reaches 
the ground before the seed above falls off. These trees 
greatly aid the formation of new land, as the mass of aerial 
roots which arch out from the stem to a considerable distance 
collects mud and floating refuse, and so raises and consoli- 
dates the shore ; while the young plants, often dropping from 
the farthest extremity of the branches, rapidly extend the 
domain of vegetation to the farthest possible limits. The 
branches, too, send down slender roots like those of the 
banyan, and become independent trees. Thus a complete 
woody labyrinth is formed ; and the network of tough roots 
and stems resists the action of the tides, and enables the 
mud brought down by great tropical rivers to be converted 
into solid land far more rapidly than it could be without 
this aid. 

Sensitive Plants 

Among the more humble forms of vegetation that attract 
the traveller's notice none are more interesting than the 
sensitive species of Mimosa. These are almost all natives of 
South America, but one species, Mimosa pudica, has spread 
to Africa and Asia, so that sensitive plants now abound as 
wayside weeds in many parts both of the eastern and west- 
ern tropics, sometimes completely carpeting the ground with 



u 8QUAT0KIAL VEGETATION 263 

their delicate foliage. Where a large surface of ground is 
thus covered the effect of walking over it is most peculiar. 
At each step the plants for some distance round suddenly 
droop, as if struck with paralysis, and a broad track of 
prostrate herbage, several feet wide, is distinctly marked out 
by the different colour of the closed leaflets. The explana- 
tion of this phenomenon given by botanists is not very 
satisfactory ; ' while the purpose or use of the peculiarity is 
stiU more mysterious, seeing that out of more than two 
hundred species belonging to this same genus Mimosa, only 
a small number are sensitive in any remarkable degree, and 
in the whole vegetable kingdom there are but few other 
plants which possess more than the rudiments of a similar 
property. The true sensitive plants are all low-growing herbs 
or shrubs with delicate foliage, which might possibly be liable 
to destruction by herbivorous animals, a fate which they may 
perhaps escape by their singular power of suddenly collapsing 
before the jaws opened to devour them. The fact that one 
species has been naturalised as a weed over so wide an area 
in the tropics, seems to show that it possesses some ad- 
vantage over the generality of tropical weeds. It is, however, 
curious that, as the most sensitive species of Mimosa are 
somewhat prickly, so easy and common a mode of protec- 
tion as the development of stronger spines should here 
have failed ; and that its place should be supplied by so 
singular a power as that of simulating death in a manner 
which suggests the possession of both sensation and volun- 
tary motion. 

Comparative Scarcity of Flowers 

It is a very general opinion among inhabitants of our 
temperate climes that amid the luxuriant vegetation of the 
tropics there must be a grand display of floral beauty, and 
this idea is supported by the number of large and showy 
flowers cultivated in our hothouses. The fact is, however, 
that in proportion as the general vegetation becomes more 
luxuriant, flowers form a less and less prominent feature; 
and this rule applies not only to the tropics but to the tem- 

1 See Nature, vol. xvi. p. 349, where the German botanist Pfeffer's theoiy 
us given. 



264 TROPICAL NATURE 



perate and frigid zones. It is amid the scanty vegetation of 
the higher mountains and towards the limits of perpetual 
snow that the alpine flowers are most brilliant and conspicu- 
ous. Our own meadows and pastures and hillsides produce 
more gay flowers than our woods and forests ; and, in the 
tropics, it is in the parts where vegetation is less dense and 
luxuriant that flowers most abound. In the damp and 
uniform climate of the equatorial zone the mass of vegeta- 
tion is greater and more varied than in any other part of the 
globe, but in the great virgin forests themselves flowers are 
rarely seen. After describing the forests of the Lower 
Amazon, Mr. Bates asks : " But where were the flowers 1 
To our great disappointment we saw none, or only such as 
were insignificant in appearance. Orchids are rare in the 
dense forests of the lowlands, and I believe it is now tolerably 
well ascertained that the majority of the forest trees in 
equatorial Brazil have small and inconspicuous flowers." ^ 
My friend Dr. Richard Spruce assured me that by far the 
greater part of the plants gathered by him in equatorial 
America had inconspicuous green or white flowers. My own 
observations in the Aru Islands for six months, and in Borneo 
for more than a year, while living almost wholly in the 
forests, are quite in accordance with this view. Cpnspicuous 
masses of showy flowers are so rare that weeks and months 
may be passed without observing a single flowering plant 
worthy of special admiration. Occasionally some tree or 
shrub will be seen covered with magnificent yellow or 
crimson or purple flowers, but it is usually an oasis of colour 
in a desert of verdure, and therefore hardly afiects the 
general aspect of the vegetation. The equatorial forest is too 
gloomy for flowers or generally even for much foliage, except 
of ferns and other shade-loving plants ; and were it not that 
the forests are broken up by rivers and streams, by mountain 
ranges, by precipitous rocks and by deep ravines, there would 
be far fewer flowers visible than there are. Some of the 
great forest trees have showy blossoms, and when these are 
seen from an elevated point looking over an expanse of tree- 
tops the effect is very grand ; but nothing is more erroneous 
than the statement sometimes made that tropical forest trees 

^ The Naturalist on the River Amazons, 2d ed. , p. 38. 



II EQUATORIAL VEGETATION 265 

generally have showy flowers, for it is doubtful whether the 
proportion is at all greater in tropical than in temperate 
zones. On such natural exposures as steep mountain sides, 
the banks of rivers, or ledges of precipices, and on the 
margins of such artificial openings as roads and forest clear- 
ings, whatever floral beauty is to be found in the more 
luxuriant parts of the tropics is exhibited. But even in such 
favoui'able situations it is not the abundance and beayty of 
the flowers but the luxuriance and the freshness of the foKage, 
and the grace and infinite variety of the forms of vegetation, 
that will most attract the attention and extort the admiration 
of the traveller. Occasionally indeed you will come upon 
shrubs gay with blossoms or trees festooned with flowering 
creepers ; but, on the other hand, you may travel for a 
hundred miles and see nothing but the varied greens of the 
forest foliage and the deep gloom of its tangled recesses. In 
Mr. Belt's Naturalist in Nicaragua, he thus describes the 
great virgin forests of that country which, being in a mount- 
ainous region and on the margin of the equatorial zone, are 
among the most favourable examples. " On each side of the 
road great trees towered up, carrying their crowns out of 
sight amongst a canopy of foliage, and with lianas hanging 
from nearly every bough, and passing from tree to tree, 
entangling the giants in a great network of coiling cables. 
Sometimes a tree appears covered with beautiful flowers 
which do not belong to it but to one of the lianas that twines 
through its branches and sends down great rope-Hke stems to 
the ground. Climbing ferns and vanilla cling to the trunks, 
and a thousand epiphytes perch themselves on the branches. 
Amongst these are large arums that send down long aerial 
roots, tough and strong, and universally used instead of 
cordage by the natives. Amongst the undergrowth several 
small species of palms, varying in height from two to fifteen 
feet, are common ; and now and then magnificent tree ferns 
sending off" their feathery crowns twenty feet from the ground 
delight the sight by their graceful elegance. Great broad- 
leaved heliconias, leathery melastomse, and succulent-stemmed, 
lop-sided, leaved, and flesh-coloured begonias are abundant, 
and typical of tropical American forests ; but not less so are 
the cecropia trees, with their white stems and large palmated 



266 TROPICAL NATURE 



leaves standing up like great candelabra. Sometimes the 
ground is carpeted with large flowers, yellow, pink, or white, 
that have fallen from some invisible tree-top above ; or the air 
is filled with a delicious perfume, the source of which one seeks 
around in vain, for the flowers that cause it are far overhead 
out of sight, lost in the great overshadowing crown of verdure." 

Although, as has been shown elsewhere, it may be 
doubted whether light directly produces floral colour, there 
can b*e no doubt that it is essential to the growth of vegeta- 
tion and to the full development of foliage and of flowers. 
In the forests all trees, and shrubs, and creepers struggle 
upwards to the light, there to expand their blossoms and 
ripen their fruit. Hence, perhaps, the abundance of climbers 
which make use of their more sturdy companions to reach 
this necessary of vegetable life. Yet even on the upper 
surface of the forest, fully exposed to the light and heat of 
the tropical sun, there is no special development of coloured 
flowers. When from some elevated point you can gaze down 
upon an unbroken expanse of woody vegetation, it often 
happens that not a single patch of bright colour can be dis- 
cerned. At other times, and especially at the beginning of 
the dry season, you may behold scattered at wide intervals 
over the mottled-green surface a few masses of yellow, white, 
pink, or more rarely of blue colour, indicating the position of 
handsome flowering trees. 

The well-established relation between coloured flowers 
and the need of insects to fertilise them may perhaps be con- 
nected with the comparative scarcity of the former in the 
equatorial forests. The various forms of life are linked to- 
gether in such mutual dependence that no one can inordi- 
nately increase without bringing about a corresponding increase 
or diminution of other forms. The insects which are best 
adapted to fertilise flowers cannot probably increase much 
beyond definite limits, because in doing so they would lead to 
a corresponding increase of insectivorous birds and other 
animals which would keep them down. The chief fertilisers 
— ^bees and butterflies — have enemies at every stage of their 
growth, from the egg to the perfect insect, and their numbers 
are, therefore, limited by causes quite independent of the 
supply of vegetable food. It may, therefore, be the case that 



« EQUATORIAL YEGETATlON 267 

the numbers of suitable insects are totally inadequate to the 
fertilisation of the countless millions of forest trees over such 
vast areas as the equatorial zone presents, and that, in con- 
sequence, a large proportion of the species have become 
adapted either for self-fertilisation, or for cross-fertilisation by 
the agency of the wind. Were there not some such limita- 
tion as this, we should expect that the continued struggle for 
existence among the plants of the tropical forests would have 
led to the acquisition, by a much larger proportion of them, 
of so valuable a character as bright- coloured flowers, this 
being almost a necessary preliminary to a participation in the 
benefits which have been proved to arise from cross-fertilisa- 
tion by insect agency. 

Condvding Eemarks on Tropical Vegetation 

In concluding this general sketch of the aspects of tropical 
vegetation, we will attempt briefly to summarise its main 
features. The primeval forests of the equatorial zone are 
grand and overwhelming by their vastness, and by the display 
of a force of development and vigour of growth rarely or 
never witnessed in temperate climates. Among their best 
distinguishing features are the variety of forms and species 
which everywhere meet and grow side by side, and the extent 
to which parasites, epiphytes, and creepers fill up every avail- 
able station with peculiar modes of Ufe. If the traveller 
notices a particular species and wishes to find more like it, he 
may often turn his eyes in vain in every direction. Trees of 
varied forms, dimensions, and colours are around him, but he 
rarely sees any one of them repeated. Time after time he 
goes towards a tree which looks like the one he seeks, but 
a closer examination proves it to be distinct. He may at 
length, perhaps, meet with a second specimen half a mile off, 
or may faU altogether, till on another occasion he stumbles 
on one by accident. 

The absence of the gregarious or social habit, so general in 
the forests of extra-tropical countries, is probably dependent 
on the extreme equability and permanence of the climate. 
Atmospheric conditions are much more important to the 
growth of plants than any others. Their severest struggle 
for existence is against chmate. As we approach towards 



268 TKOPICAL NATURE 



regions of polar cold or desert aridity the variety of groups 
and species regularly diminishes ; more and more are unable 
to sustain the extreme cUmatal conditions, till at last we find 
only a few specially organised forms which are able to main- 
tain their existence. In the extreme north, pine or birch 
trees — in the desert, a few palms and prickly shrubs or aro- 
matic herbs — alone survive. In the equable equatorial zone 
there is no such struggle against climate. Every form of 
vegetation has become alike adapted to its genial heat and 
ample moisture, which has probably changed Kttle even 
throughout geological periods ; and the never ceasing struggle 
for existence between the various species in the same area has 
resulted in a nice balance of organic forces, which gives the 
advantage, now to one, now to another species, and prevents 
any one type of vegetation from monopolising territory to 
the exclusion of the rest. The same general causes have led 
to the filling up of every place in nature with some specially 
adapted form. Thus we find a forest of smaller trees adapted 
to grow in the shade of greater trees. Thus we find every 
tree supporting numerous other forms of vegetation, and some 
so crowded with epiphytes of various kinds that their forks 
and horizontal branches are veritable gardens. Creeping 
ferns and arums run up the smoothest trunks ; an immense 
variety of climbers hang in tangled masses from the branches 
and mount over the highest tree- tops. Orchids, bromeUas, 
arums, and ferns grow from every boss and crevice, and cover 
the fallen and decaying trunks with a graceful drapery. 
Even these parasites have their own parasitical growth, their 
leaves often supporting an abundance of minute creeping 
mosses and hepaticse. But the uniformity of climate which 
has led to this rich luxuriance and endless variety of vegetation 
is also the cause of a monotony that in time becomes oppress- 
ive. To quote the words of Mr. Belt : " Unknown are the 
autumn tints, the bright browns and yellows of English woods ; 
much less the crimsons, purples, and yellows of Canada, where 
the dying foliage rivals, nay excels, the expiring dolphin in 
splendour. Unknown the cold sleep of winter ; unknown the 
lovely awakening of vegetation at the first gentle touch of 
spring. A ceaseless round of ever -active life weaves the 
fairest scenery of the tropics into one monotonous whole, of 



n EQUATORIAL VEGETATION 269 

wMch the component parts exhibit in detail untold variety 
and beauty." ^ 

To the student of nature the vegetation of the tropics wiU 
ever be of surpassing interest, whether for the variety of 
forms and structures which it presents, for the boundless 
energy with which the life of plants is therein manifested, or 
for the help which it gives us in our search after the laws 
which have determined the production of such infinitely 
varied organisms. When, for the first time, the traveller 
wanders in these primeval forests, he can scarcely fail to 
experience sensations of awe, akin to those excited by the 
trackless ocean or the alpine snowfields. There is a vastness, 
a solemnity, a gloom, a sense of solitude and of human 
insignificance, which for a time overwhelm him ; and it is only 
when the novelty of these feelings have passed away that he 
is able to turn his attention to the separate constituents that 
combine to produce these emotions, and examine the varied 
and beautiful forms of life which, in inexhaustible profusion, 
are spread around him. 

' The NaluraMat in Nicmagua, p. 56. 



Ill 

ANIMAL LIFE IN THE TROPICAL FORESTS 

Difficulties of the Subject — General Aspect of tlie Animal Life of Equatorial 
Forests — Diurnal Lepidoptera or Butterflies — Peculiar Hatits of Tro- 
pical Butterflies — Ants, Wasps, and Bees — Ants — Special Relations 
between Ants and Vegetation — Wasps and Bees — Orthoptera and 
other Insects — ^Beetles — Wingless Insects — General Observations on 
Tropical Insects — Birds : PaiTots — Pigeons — Picariae — Cuckoos — Tro- 
gons, Barbets, Toucans, and Hornbills — Passeres — Reptiles and 
Amphibia ; Lizards — Snakes — Frogs and Toads — Mammalia : 
Monkeys — Bats — Summary of the Aspects of Animal Life in the 
Tropics. 

The attempt to give some account of the general aspects of 
animal life in the equatorial zone presents far greater diffi- 
culties than in the case of plants! On the one hand, animals 
rarely play any important part in scenery, and their entire 
absence may pass quite unnoticed; while the abundance, 
variety, and character of the vegetation are among those 
essential features that attract every eye. On the other hand, 
so many of the more important and characteristic types of 
animal Ufe are restricted to one only out of the three great 
divisions of equatorial land, that they can hardly be claimed 
as characteristically tropical ; while the more extensive zoolog- 
ical groups which have a wide range in the tropics and do 
not equally abound in the temperate zones, are few in number, 
and often include such a diversity of forms, structures, and 
habits as to render any typical characterisation of them 
impossible. We must then, in the first place, suppose that 
our traveller is on the look-out for all signs of animal life ; 
and that, possessing a general acquaintance as an out-door 
observer with the animals of our own country, he carefully 



HI ANIMAL LIFE IN THE TROPICAL FORESTS 271 

notes those points in which, the forests of the equatorial zone 
offer different phenomena. Here, as in the case of plants, we 
exclude all zoological science, classifications, and nomenclature, 
except in as far as it is necessary for a clear understanding 
of the several groups of animals referred to. We shall there- 
fore follow no systematic order in our notes, except that 
which would naturally arise from the abundance or prominence 
of the objects themselves. We further suppose our traveller 
to have no prepossessions, and to have no favourite group, in 
the search after which he passes by other objects which, in 
view of their frequent occurrence in the landscape, are really 
more important. 

General Aspect of the Animal Life of Equatorial Forests 

Perhaps the most general impression produced by a first 
acquaintance with the equatorial forests is the comparative 
absence of animal life. Beast, bird, and insect alike require 
looking for, and it very often happens that we look for them 
in vain. On this subject Mr. Bates, describing one of his 
early excursions into the primeval forests of the Amazon 
valley, remarks as follows : " We were disappointed in not 
meeting with any of the larger animals of the forest. There 
was no tumultuous movement or sound of life. We did not 
see or hear monkeys, and no tapir or jaguar crossed our path. 
Birds also appeared to be exceedingly scarce." Again : " I 
afterwards saw reason to modify my opinion, founded on first 
impressions, with regard to the amount and variety of animal 
life in this and other parts of the Amazonian forests. There 
is, in fact, a great variety of mammals, birds, and reptiles, but 
they are widely scattered and all excessively shy of man. The 
region is so extensive and uniform in the forest clothing of its 
surface, that it is only at long intervals that animals are seen 
in abundance, where some particular spot is found which is 
more attractive than others. Brazil, moreover, is throughout 
poor in terrestrial mammals, and the species are of small size ; 
they do not, therefore, form a conspicuous feature in the 
forests. The huntsman would be disappointed who expected 
to find here flocks of animals similar to the buffalo-herds of 
North America, or the swarms of antelopes and herds of 
ponderous pachyderms of Southern Africa. We often read 



272 TROPICAL NATURE 



in books of travel of the silence and gloom of the Brazilian 
forests. They are realities, and the impression deepens on a 
longer acquaintance. The few sounds of birds are of that 
pensive and mysterious character which intensifies the feeling 
of solitude rather than imparts a sense of life and cheerfulness. 
Sometimes in the midst of the stillness a sudden yell or scream 
will startle one ; this comes from some defenceless fruit-eating 
animal which is pounced upon by a tiger-cat or a boa-con- 
strictor. Morning and evening the howling monkeys make a 
most fearful and harrowing noise, under which it is difiicult 
to keep up one's buoyancy of spirit. The feeling of inhos- 
pitable wildness which the forest is calculated to inspire is 
increased tenfold under this fearful uproar. Often, even in 
the still mid-day hours, a sudden crash will be heard resound- 
ing afar through the wilderness, as some great bough or entire 
tree falls to the ground." With a few verbal alterations these 
remarks will apply equally to the primeval forests of the 
Malay Archipelago; and it is probable that those of West 
Africa offer no important differences in this respect. There 
is, nevertheless, one form of life which is very rarely absent 
in the more luxuriant parts of the tropics, and which is more 
often so abundant as to form a decided feature in the scene. 
It is therefore the group which best characterises the equa- 
torial zone, and should form the starting-point for our review. 
This group is that of the 

Diurnal Lepidoptera or Butterflies 

Wherever in the equatorial zone a considerable extent of » 
the primeval forest remains, the observer can hardly fail to be 
struck by the abundance and the conspicuous beauty of the 
butterflies. Not only are they abundant in individuals, but 
their large size, their elegant forms, their rich and varied 
colours, and the number of distinct species almost everywhere 
to be met with, are equally remarkable. In many localities 
near the northern or southern tropics they are perhaps equally 
abundant, but these spots are more or less exceptional, whereas 
within the equatorial zone, and with the limitations above 
stated, butterflies form one of the most constant and most 
conspicuous displays of animal Ufe. They abound most in 
old and tolerably open roads and pathways through the forest. 



tit ANIMAL LIFE IN THE TROPICAL FORESTS 273 

but they are also very plentiful in old settlements in which 
fruit-trees and shrubbery offer suitable haunts. In the vicinity 
of such old towns as Malacca and Amboyna in the East, and 
of Para and Rio de Janeiro in the West, they are especially 
abundant, and comprise some of the handsomest and most 
remarkable species in the whole group. Their aspect is 
altogether different from that presented by the butterflies of 
Europe and of most temperate countries. A considerable 
proportion of the species are very large, six to eight inches 
across the wings being not uncommon among the Papilionidse 
and Morphidse, whUe several species are even larger. This 
great expanse of wings is accompanied by a slow flight ; and, 
as they usually keep near the ground and often rest, some- 
times with closed and sometimes with expanded wings, these 
noble insects really look larger and are much more con- 
spicuous objects than the majority of our native birds. The 
first sight of the great blue Morphos flapping slowly along in 
the forest roads near Para, of the large white-and-black semi- 
transparent Ideas floating airily about in the woods near 
Malacca, and of the golden -green Ornithopteras sailing on 
bird -like wing over the flowering shrubs which adorn the 
beach of the K6 and Aru islands, can never be forgotten by 
any one with a feeling of admiration for the new and beautiful 
in nature. Next to the size, the infinitely varied and dazzling 
hues of these insects most attract the observer. Instead of 
the sober browns, the plain yellows, and the occasional patches 
of red, or blue, or orange that adorn our European species, 
we meet with the most intense metaUic blues, the piu-est 
satiny greens, the most gorgeous crimsons, not in small spots 
but in large masses, relieved by a black border or background. 
In others we have contrasted bands of blue and orange, or of 
crimson and green, or of silky yellow relieved by velvety 
black. In not a few the wings are powdered over with scales 
and spangles of metallic green, deepening occasionally into 
blue or golden or deep red spots. Others again have spots 
and markings as of molten silver or gold, while several have 
changeable hues, like shot-silk or richly-coloured opal. The 
form of the wings, again, often attracts attention. Tailed 
hind-wings occur in almost all the families, but vary much in 
character. In some the tails are broadly spoon -shaped, in 

T 



274 TROPICAL NATUilE 



otters long and pointed. Many have double or triple tails, 
and some of the smaller species have them immensely elon- 
gated and often elegantly curled. In some groups the wings 
are long and narrow, in others strongly falcate ; and though 
many fiy with immense rapidity, a large number flutter lazily 
along, as if they had no enemies to fear, and therefore no 
occasion to hurry. 

The number of species of butterflies inhabiting any one 
locality is very variable, and is, as a rule, far larger in 
America than in the Eastern hemisphere ; but it everywhere 
very much surpasses the numbers in the temperate zone. A 
few months' assiduous collecting in any of the Malay islands 
will produce from 150 to 250 species of butterflies, and thirty 
or forty species may be obtained any fine day in good locali- 
ties. In the Amazon valley, however, much greater results 
may be achieved. A good day's collecting will produce from 
forty to seventy species, while in one year at Para about 600 
species were obtained. More than 700 species of butterflies 
actually inhabit the district immediately around the city of 
Para, and this, as far as we yet know, is the richest spot on 
the globe for diurnal lepidoptera. At Ega, during four years' 
collecting, Mr. Bates obtained 550 species, and these, on the 
whole, surpassed those of Para in variety and beauty. Mr. 
Bates thus speaks of a favourite locality on the margin of the 
lake near Ega : " The number and variety of gaUy-tinted 
butterflies, sporting about in this grove on sunny days, were 
so great that the bright moving flakes of colour gave quite a 
character to the physiognomy of the place. It was impossible 
to walk far without disturbing flocks of them from the damp 
sand at the edge of the water, where they congregated to 
imbibe the moisture. They were of almost all colours, sizes, 
and shapes ; I noticed here altogether eighty species, belonging 
to twenty-two distinct genera. The most abundant, next to 
the very common sulphur-yellow and orange-coloured kinds, 
were about a dozen species of Eunica, which are of large size 
and conspicuous from their liveries of glossy dark blue and 
purple. A superbly adorned creature, the CaUithea markii, 
having wings of a thick texture, coloured sapphire-blue and 
orange, was only an occasional visitor. On certain days, when 
the weather was very calm, two small gilded species (Sym- 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 275 

machia trochilus and colubris) literally swarmed on the sands, 
their glittering wings lying wide open on the flat surface." ^ 

When we consider that only sixty-four species of butter- 
flies have been found in Britain and about 150 in Germany, 
many of which are very rare and local, so that these numbers 
are the result of the work of hundreds of collectors for a long 
series of years, we see at once the immense wealth of the 
equatorial zone in this form of life. 

Peculiar Habits of Tropical ButterjUes 
The habits of the butterflies of the tropics ofier many curious 
points rarely or never observed among those of the temperate 
zone. The majority, as with us, are truly diurnal, but there 
are some Eastern Morphidae and the entire American family 
BrassoMse, which are crecuspular, coming out after sunset 
and flitting about the roads till it is nearly dark. Others, 
though flying in the daytime, are only found in the gloomiest 
recesses of the forest, where a constant twilight may be said 
to prevail. The majority of the species fly at a moderate 
height (from five to ten feet above the ground), while a few 
usually keep higher up and are difficult to capture; but a 
large number, especially the Satyridee, many Erycinidse, and 
some few Nymphalidse, keep always close to the ground and 
usually settle on or among the lowest herbage. As regards 
the mode of flight, the extensive and almost exclusively 
tropical families of Heliconidae and Danaidse fly very slowly, 
with a gentle undulating or floating motion which is almost 
peculiar to them. Many of the strong-bodied Nymphalidas 
and Hesperidse, on the other hand, have an excessively rapid 
flight, darting by so swiftly that the eye cannot foUow them, 
and in some cases producing a deep sound louder than that of 
the humming-birds. 

The places they frequent, and their mode of resting, 
are various and often remarkable. A considerable number 
frequent damp open places, especially river -sides and the 
margins of pools, assembling together in flocks of hundreds of 
individuals ; but these are almost entirely composed of males, 
the females remaining in the forests, where, towards the after 
noon, their partners join them. The majority of butterflies 
' The Naturalist on the River Amazons, 2d ed., p. 331. 



276 TROPICAL NATURE 



settle upon foliage and on flowers, holding their wings erect 
and folded together, though early in the morning, or when 
newly emerged from the chrysalis, they often expand them to 
the sun. Many, however, have special stations and attitudes. 
Some settle always on tree -trunks, usually with the wings 
erect, but the Ageronias expand them and always rest with 
the head downwards. Many NymphaUdae prefer resting on 
the top of a stick ; others choose bushes with dead leaves ; 
others settle on rocks or sand or in dry forest paths. Pieces 
of decaying animal or vegetable matter are very attractive to 
certain species, and if disturbed they will sometimes return to 
the same spot day after day. Some Hesperidse, as well as 
species of the genera Cyrestis and Symmachia, and a few 
others, rest on the ground with their wings fully expanded 
and pressed closely to the surface, as if exhibiting themselves 
to the greatest advantage. The beautiful little Erycinidse of 
South America vary remarkably in their mode of resting. 
The majority always rest on the under surface of leaves with 
their wings expanded, so that when they settle they suddenly 
disappear from sight. Some, however, as the elegant gold- 
spotted Helicopis cupido, rest beneath leaves with closed 
wings. A few, as the genera Charis and Themone, for 
example, sit on the upper side of leaves with their wings 
expanded ; while the gorgeously-coloured Erycinas rest with 
wings erect and exposed as in the majority of butterflies. 
The Hesperidae vary in a somewhat similar manner. All rest 
on the upper side of leaves or on the ground, but some close 
their wings, others expand them, and a third group keep 
the upper pair of wings raised while the hind wings are 
expanded, a habit found in some of our European species. 
Many of the Lycsenidse, especially the Theclas, have the 
curious habit, while sitting with their wings erect, of 
moving the lower pair over each other in opposite directions, 
giving them the strange appearance of eccentrically revolving 
discs. 

The great majority of butterflies disappear at night, rest- 
ing concealed amid foliage, or on sticks or trunks, or in such 
places as harmonise with their colours and markings ; but the 
gaily-coloured Heliconidae and Daniadse seek no such conceal- 
ment, but rest at night hanging at the ends of slender twigs 



in ANIMAL LIFE IN THE TROPICAL FORESTS 277 

or upon fully exposed leaves. Being uneatable they have no 
enemies and need no concealment. Day-flying moths of 
brilliant or conspicuous colours are also comparatively abund- 
ant in the tropical forests. Most magnificent of aU are the 
Uranias, whose long-tailed green -and -gold powdered wings 
resemble those of true swallow-tailed butterflies. Many 
Agaristidse of the East are hardly inferior in splendour, while 
hosts of beautiful clearwings and j^geriidse add greatly to 
the insect beauty of the equatorial zone. 

The wonderful examples aff'orded by tropical butterflies of 
the phenomena of sexual and local variation, of protective 
modifications, and of mimicry, have been fully discussed 
elsewhere. For the study of the laws of variation in all its 
forms, these beautiful creatures are unsurpassed by any class 
of animals, both on account of their great abundance, and the 
assiduity with which they have been collected and studied. 
Perhaps no group exhibits the distinctions of species and 
genera with such precision and distinctness, due, as Mr. Bates 
has well observed, to the fact that aU the superficial signs of 
change in the organisation are exaggerated, by their affecting 
the size, shape, and coloiu- of the wings, and the distribution 
of the ribs or veins which form their framework. The minute 
scales or feathers with which the wings are clothed are coloured 
in regular patterns, which vary in accordance with the slightest 
change in the conditions to which the species are exposed. 
These scales are sometimes absent in spots or patches, and 
sometimes over the greater part of the wings, which then 
become transparent, relieved only by the dark veins and by 
delicate shades or small spots of vivid colour, producing a 
special form of delicate beauty characteristic of many South 
American butterflies. The following remark by Mr. Bates 
will fitly conclude our sketch of these lovely insects. "It 
may be said, therefore, that on these expanded membranes 
Nature writes, as on a tablet, the story of the modifications of 
species, so truly do all the changes of the organisation register 
themselves thereon. And as the laws of Nature must be the 
same for all beings, the conclusions furnished by this group 
of insects must be applicable to the whole organic world ; 
therefore the study of butterflies — creatures selected as the 
types of airiness and frivolity — instead of being despised, will 



278 TROPICAL NATURE m 

some day be valued as one of the most important branches of 
biological science." ^ 

Next after the butterflies in importance, as giving an air 
of Uf e and interest to tropical nature, we must place the birds ; 
but to avoid unnecessary passage, to and fro, among unrelated 
groups, it wiU be best to follow on with a sketch of such 
other groups of insects as from their numbers, variety, habits, 
or other important features, attract the attention of the 
traveller from colder climates. We begin then with a group 
which, owing to their small size and obscure colours, would 
attract little attention, but which nevertheless, by the 
iiniversality of their presence, their curious habits, and the 
annoyance they often cause to man, are sure to force them- 
selves upon the attention of every one who visits the tropics. 

Ants, Wasps, and Bees 

The hymenopterous insects of the tropics are, next to the 
butterflies, those which come most prominently before the 
traveller, as they love the sunshine, frequent gardens, houses, 
and roadways as well as the forest shades, never seek conceal- 
ment, and are many of them remarkable for their size or 
form, or are adorned with beautiful colours and conspicuous 
markings. Although ants are, perhaps, on the whole, the 
smallest and the least attractive in appearance of all tropical 
insects, yet, owing to their being excessively abundant and 
almost omnipresent, as well as on account of their curious 
habits and the necessity of being ever on the watch against 
their destructive powers, they deserve our first notice. 

Ants are found everywhere. They abound in houses, 
some living underground, others in the thatched roofs, on the 
under surface of which they make their nests, while covered 
ways of earth are often constructed upon the posts and doors. 
In the forests they live on the ground, under leaves, on the 
branches of trees, or under rotten bark ; while others actually 
dwell in living plants, which seem to be specially modified so 
as to accommodate them. Some sting severely, others only 
bite ; some are quite harmless, others exceedingly destructive. 
The number of different kinds is very great. In India and 
the Malay Archipelago nearly 500 different species have been 
* Bates, The Natv/ralist on the River Amazons, 2d ed., p. 413. 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 279 

found, and other tropical countries are no doubt equally rich. 
I will first give some account of the various species observed 
in the Malay islands, and afterwards describe some of the 
more interesting South American groups, which have been 
so carefully observed by Mr. Bates on the Amazons and by 
Mr. Belt in Nicaragua. 

Among the very commonest ants in all parts of the world 
are the species of the family Formicidse, which do not sting, 
and are most of them quite harmless. Some make delicate 
papery nests, others live under stones or among grass. 
Several of them accompany Aphides to feed upon the sweet 
secretions from their bodies. They vary in size from the 
large Formica gigas, more than an inch long, to minute 
species so small as to be hardly visible. Those of the genus 
Polyrachis, which are plentiful in all Eastern forests, are 
remarkable for the extraordinary hooks and spines with which 
their bodies are armed, and they are also in many cases 
beautifully sculptured or furrowed. They are not numerous 
individually, and are almost all arboreal, crawling about bark 
and foliage. One species has processes on its back just like 
fish-hooks, others are armed with long, straight spines. They 
generally form papery nests on leaves, and when disturbed 
they rush out and strike their bodies against the nest so as to 
produce a loud rattling noise ; but the nest of every species 
difiers from those of all others either in size, shape, or position. 
As they all live in rather small commimities in exposed 
situations, are not very active, and are rather large and con- 
spicuous, they must be very much exposed to the attacks of 
insectivorous birds and other creatures, and having no sting 
or powerful jaws with which to defend themselves, they would 
be liable to extermination without some special protection. 
This protection they no doubt obtain by their hard smooth 
bodies, and by the curious hooks, spines, points, and bristles 
with which they are armed, which must render them unpalat- 
able morsels, very liable to stick in the jaws or throats of their 
captors. 

A curious and very common species in the Malay islands 
is the green ant (CEcophylla smaragdina), a rather large, long- 
legged, active, and intelligent-looking creature, which lives in 
large nests formed by gluing together the edges of leaves, 



280 TROPICAL NATURE 



especially of Zingiberaceous plants. When the nest is touched 
a number of the ants rush out, apparently in a great rage, 
stand erect, and make a loud rattling noise by tapping against 
the leaves. This no doubt frightens away many enemies, and 
is their only protection ; for though they attempt to bite, their 
jaws are blunt and feeble, and they do not cause any pain. 

Coming now to the stinging groups, we have first a number 
of solitary ants of the great genus Odontomachus, which are 
seen wandering about the forest and are conspicuous by their 
enormously long and slender hooked jaws. These are not 
powerful, but serve admirably to hold on by while they sting, 
which they do pretty severely. The Poneridse are another group 
of large-sized ants which sting acutely. They are very varied 
in species but are not abundant individually. The Ponera 
clavata of Guiana is one of the worst stinging ants known. 
It is a large species, frequenting the forests on the ground, and 
is much dreaded by the natives, as its sting produces intense 
pain and illness. I was myself stung by this or an allied species 
when walking barefoot in the forest on the Upper Eio Negro. 
It caused such pain and swelling of the leg that I had some 
difficulty in reaching home, and was confined to my room for two 
days. Sir Robert Schomburgh suffered more ; for he fainted 
with the pain, and had an attack of fever in consequence. 

We now come to the Myrmecidae, which may be called 
the destroying ants, from their immense abundance and de- 
structive propensities. Many of them sting most acutely, 
causing a pain like that of a sudden burn, whence they are 
often called " fire-ants." They often swarm in houses and 
devour everything eatable. Isolation by water is the only 
security, and even this does not always succeed, as a little 
dust on the surface will enable the smaller species to get 
across. Oil is, however, an effectual protection, and after 
many losses of valuable insect specimens, for which ants have 
a special affection, I always used it. One species of this 
group, a small black Crematogaster, took possession of my 
house in New Guinea, building nests in the roof and making 
covered ways down the posts and across the floor. They also 
occupied the setting boards I used for pinning out my butter- 
flies, filling up the grooves with cells and storing them with 
small spiders. They were in constant motion, running over 



in ANIMAL LIFE IN THE TROPICAL FORESTS 281 

my table, in my bed, and all over my body. Luckily, they 
were diurnal, so that on sweeping out my bed at night I 
could get on pretty well j but during the day I could always 
feel some of them running over my body, and every now and 
then one would give me a sting so sharp as to make me jump 
and search instantly for the oifender, who was usually found 
holding on tight with his jaws and thrusting in his sting with 
all his might. Another genus, Pheidole, consists of forest 
ants, living under rotten bark or in the ground, and very 
voracious. They are brown or blackish, and are remarkable 
for their great variety of size and form in the same species, 
the largest having enormous beads many times larger than 
their bodies, and being at least a hundred times as bulky as 
the smallest individuals. These great-headed ants are very 
sluggish and incapable of keeping up with the more active 
small workers, which often surround and drag them along as 
if they were wounded soldiers. It is difficult to see what use 
they can be in the colony, unless, as Mr. Bates suggests, they 
are mere baits to be attacked by insect-eating birds, and thus 
save their more useful companions. These ants devour grubs, 
white ants, and other soft and helpless insects, and seem to 
take the place of the foraging ants of America and driver 
ants of Africa, though they are far less numerous and less 
destructive. An allied genus, Solenopsis, consists of red ants, 
which, in the Moluccas, frequent houses, and are a most 
terrible pest. They form colonies underground, and work 
their way up through the floors, devouring everything eat- 
able. Their sting is excessively painful, and some of the 
species are hence called fire-ants. When a house is infested 
by them, all the tables and boxes must be supported on 
blocks of wood or stone placed in dishes of water, as even 
clothes not newly washed are attractive to them ; and woe to 
the poor fellow who puts on garments in the folds of which 
a dozen of these ants are lodged. It is very difficult to 
preserve bird skins or other specimens of natural history 
where these ants abound, as they gnaw away the skin round 
the eyes and the base of the bill, and if a specimen is laid 
down for even half an hoxu" in an unprotected place it will 
be ruined. I remember once entering a native house to rest 
and eat my lunch ; and having a large tin collecting-box full 



282 TROPICAL NATURE 



of rare butterflies and other insects, I laid it down on the 
bench by my side. On leaving the house I noticed some ants 
on it, and on opening the box found only a mass of detached 
wings and bodies, the latter in process of being devoured by 
hundreds of fire-ants. 

The celebrated Sauba ant of America (CEcodoma cepha- 
lotes) is allied to the preceding, but is even more destructive, 
though it seems to confine itself to vegetable products. It 
forms extensive underground galleries, and the earth brought 
up is deposited on the surface, forming huge mounds some- 
times thirty or forty yards in circumference and from one 
to three feet high. On first seeing these vast deposits of 
red or yellow earth in the woods near Para, it was hardly 
possible to believe they were not the work of man, or at 
least of some large burrowing animal. In these underground 
caves the ants store up large quantities of leaves, which they 
obtain from living trees. They gnaw out circular pieces and 
carry them away along regular paths a few inches wide, 
forming a stream of apparently animated leaves. The great 
extent of the subterranean workings of these ants is no doubt 
due in part to their permanence in one spot, so that when 
portions of the galleries fall in or are otherwise rendered 
useless, they are extended in another direction. When in 
the island of Marajo, near Para, I noticed a path along which 
a stream of Saiibas were carrying leaves from a neighbouring 
thicket ; and a relation of the proprietor assured me that 
he had known that identical path to be in constant use by 
the ants for twenty years. Thus we can account for the 
fact mentioned by Mr. Bates, that the underground galleries 
were traced by smoke for a distance of seventy yards in the 
Botanic Gardens at Para ; and for the still more extraordinary 
fact related by the Eev. Hamlet Clark, that an allied species 
in Eio de Janeiro has excavated a tunnel under the bed of 
the river Parahyba, where it is about a quarter of a mile wide ! 
These ants seem to prefer introduced to native trees ; and young 
plantations of orange, coffee, or mango trees are sometimes 
destroyed by them, so that where they abound cidtivation of 
any kind becomes almost impossible. Mr. Belt ingeniously 
accounts for this preference by supposing that for ages there 
has been a kind of struggle going on between the trees 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 283 

and the ants ; those varieties of trees which were in any 
way distasteful or unsuitable escaping destruction, while the 
ants were becoming slowly adapted to attack new trees. 
Thus in time the great majority of native trees have acquired 
some protection against the ants, while foreign trees, not 
having been so modified, are more likely to be suitable for 
their purposes. Mr. Belt carried on war against them for 
four years to protect his garden in Nicaragua, and found 
that carbolic acid and corrosive sublimate were most effectual 
in destroying or driving them away. 

The use to which the ants put the immense quantities of 
leaves they carry away has been a great puzzle, and is, per- 
haps, not yet quite understood. Mr. Bates found that the 
Amazon species used them to thatch the domes of earth cover- 
ing the entrances to their subterranean galleries, the pieces of 
leaf being carefully covered and kept in position by a thin layer 
of grains of earth. In Nicaragua Mr. Belt found the under- 
ground cells full of a brown flocculent matter, which he con- 
siders to be the gnawed leaves connected by a delicate fungus 
which ramifies through the mass and which serves as food for 
the larvae ; and he believes that the leaves are really gathered 
as manure-heaps to favour the growth of this fungus ! 

When they enter houses, which they often do at night, 
the Saiibas are very destructive. Once, when traveUing on 
the Rio Negro, I had bought about a peck of rice, which was 
tied up in a large cotton handkerchief and placed on a bench 
in a native house where we were spending the night. The 
next morning we found about half the rice on the floor, the 
remainder having been carried away by the ants ; and the 
empty handkerchief was still on the bench, but with hundreds 
of neat cuts in it reducing it to a kind of sieve. ^ 

The foraging ants of the genus Eciton are another remark- 
able group, especially abundant in the equatorial forests of 
America. They are true hunters, and seem to be continually 
roaming about the forests in great bands in search of insect . 
prey. They especially devour maggots, caterpillars, white 
ants, cockroaches, and other soft insects; and their bands 

' For a full and most interesting description of the habits and instincts of 
this ant, see Bates' Naturalist an the River Amazons, 2d ed., pp. 11-18 ; 
and Belt's NOitwralist in Nicaragua, pp. 71-84. 



284 TROPICAL NATURE 



are always accompanied by flocks of insectivorous birds, who 
prey upon the winged insects that are continually trying to 
escape from the ants. They even attack wasps' nests, which 
they cut to pieces and then drag out the larvae. They bite 
and sting severely, and the traveller who accidentally steps 
into a horde of them will soon be overrun, and must make 
his escape as quickly as possible. They do not confine them- 
selves to the ground, but swarm up bushes and low trees, 
hunting every branch, and clearing them of all insect life. 
Sometimes a band will enter a house, like the driver ants in 
Africa, and clear it of cockroaches, spiders, centipedes, and 
other insects. They seem to have no permanent abode, and to 
be ever wandering about in search of prey, but they make 
temporary habitations in hollow trees or other suitable places. 
Perhaps the most extraordinary of all ants are the blind 
species of Eciton discovered by Mr. Bates, which construct a 
covered way or tunnel as they march along. On coming 
near a rotten log, or any other favourable hunting ground, 
they pour into all its crevices in search of booty, their 
covered way serving as a protection to retire to in case of 
danger. These creatures, of which two species are known, 
are absolutely without eyes ; and it seems almost impossible 
to imagine that the loss of so important a sense-organ can be 
otherwise than injurious to them. Yet on the theory of 
natural selection the successive variations by which the eyes 
were reduced and ultimately lost must all have been useful. 
It is true they do manage to exist without eyes ; but that is 
probably because, as sight became more and more imperfect, 
new instincts or new protective modifications were developed 
to supply its place, and this does not in any way account for 
so widespread and invaluable a sense having become per- 
manently lost, in creatures which still roam about and hunt 
for prey very much as do their fellows who can see. 

Special Belations between Ants and Fegetation 

Attention has recently been called to the very remarkable 
relations existing between some trees and shrubs and the ants 
which dwell upon them. In the Malay islands are several 
curious shrubs belonging to the Cinchonacese, which grow 
parasitically on other trees, and whose swollen stems are 



ni ANIMAL LIFE IN THE TROPICAL FORESTS 285 

veritable ants' nests. When very young the stems are like 
small, irregular, prickly tubers, in the hollows of which ants 
establish themselves ; and these in time grow into irregular 
masses the size of large gourds, completely honeycombed with 
the cells of ants."^ In America there are some analogous cases 
occurring in several families of plants, one of the most 
remarkable being that of certain Melastomas which have a 
kind of pouch formed by an enlargement of the petiole of 
the leaf, and which is inhabited by a colony of small ants. 
The hollow stems of the Cecropias (curious trees with pale 
bark and large palmate leaves which are white beneath) are 
always tenanted by ants, which make small entrance holes 
through the bark ; but here there seems no special adaptation 
to the wants of the insect. In a species of Acacia observed 
by Mr. Belt, the thorns are immensely large and hoUow, and 
are always tenanted by ants. When yoimg these thorns are 
soft and full of a sweetish pulpy substance, so that when the 
ants first take possession they find a store of food in their 
house. Afterwards they find a special provision of honey- 
glands on the leaf-stalks, and also small yellow fruit-like 
bodies which are eaten by the ants ; and this supply of food 
permanently attaches them to the plant. Mr. Belt believes, 
after much careful observation, that these ants protect the 
plant they Uve on from leaf-eating insects, especially from the 
destructive Sailba ants, — that they are in fact a standing 
army kept for the protection of the plant ! This view is 
supported by the fact that other plants — ^Passion-flowers for 
example — have honey-secreting glands on the young leaves 
and on the sepals of the flower-buds which constantly attract 
a small black ant. If this view is correct, we see that the 
need of escaping from the destructive attacks of the leaf- 
cutting ants has led to strange modifications in many plants. 
Those in which the foliage was especially attractive to these 
enemies were soon weeded out unless variations occurred which 
tended to preserve them. Hence the curious phenomenon of 
insects specially attracted to certain plants to protect them 
from other insects ; and the existence of the destructive leaf- 

1 These form two genera, Myrmecodia and Hydnophytum. For descrip- 
tion and figures see Mr. H. 0. Forbes' Naturalist's Wanderings in the Eastern 
Archipelago, p. 79. 



286 TROPICAL NATURE 



cutting ant in America will ttus explain why these specially 
modified plants are so much more abundant there than in the 
Old World, where no ants with equally destructive habits 
appear to exist. 

Wasps and Bees 

These insects are excessively numerous in the tropics, and, 
from their large size, their brilliant colours, and their great 
activity, they are sure to attract attention. Handsomest of 
all, perhaps, are the Scohadse, whose large and rather broad 
hairy bodies, often two inches long, are richly banded with 
yellow or orange. The Pompilidse comprise an immense 
number of large and handsome insects, with rich blue-black 
bodies and wings and exceedingly long legs. They may often 
be seen in the forests dragging along large spiders, beetles, or 
other insects they have captured. Some of the smaller 
species enter houses and build earthen cells, which they store 
with small green spiders rendered torpid by stinging, to feed 
the larvae. The Eumenidse are beautiful wasps with very 
long pedunculated bodies, which build papery cones covering 
a few cells in which the eggs are deposited. Among the bees 
the Xylocopas, or wood -boring bees, are remarkable. They 
resemble large humble-bees, but have broad, flat, shining 
bodies, either black or banded with blue ; and they often bore 
large cylindrical holes in the posts of houses. True honey- 
bees are chiefly remarkable in the East for their large semi- 
circular combs suspended from the branches of the loftiest 
trees without any covering. From these exposed nests large 
quantities of wax and honey are obtained, while the larvse 
afford a rich feast to the natives of Borneo, Timor, and other 
islands where bees abound. They are very pugnacious, and, 
when disturbed will follow the intruders for miles, stinging 
severely. 

Orthoptera and other Insects 

Next to the butterflies and ants, the insects that are most 
likely to attract the attention of the stranger in the tropics 
are the various forms of Mantidae and Phasmidse, some of 
which are remarkable for their strange attitudes and bright 
colours ; while others are among the most singular of known 
insects, owing to their resemblance to sticks and leaves. The 



lit ANIMAL LIFE IN THE TROPICAL FORESTS 287 



Mantidae — usually called "praying insects," from their habit of 
sitting with their long fore-feet held up as if in prayer — are 
really tigers among insects, lying in wait for their prey, which 
they seize with their powerful serrated fore-feet. They are 
usually so coloured as to resemble the foliage among which 
they live, and as they sit quite motionless, they are not easily 
perceived. 

The Phasmidse are perfectly inoffensive leaf-eating insects of 
very varied forms ; some being broad and leaf-like, while others 
are long and cylindrical, so as to resemble sticks, whence they 
are often called walking-stick insects. The imitative resem- 
blance of some of these insects to the plants on which they 
live is marvellous. The true leaf-insects of the East, forming 
the genus PhyUium, are the size of a moderate leaf, which their 
large wing-covers and the dilated margins of the head, thorax, 
and legs cause them exactly to resemble. The veining of the 
wings and their green tint exactly correspond to that of the 
leaves of their food-plant ; and as they rest motionless during 
the day, only feeding at night, they the more easily escape 
detection. In Java they are often kept aHve on a branch of 
the guava tree ; and it is a common thing for a stranger, when 
asked to look at this curious insect, to inquire where it is, and 
on being told that it is close under his eyes, to maintain that 
there is no insect at all, but only a branch with green leaves. 

The larger wingless stick-insects are often eight laches to 
a foot long. They are abundant in the Moluccas ; hanging on 
the shrubs that line the forest-paths ; and they resemble sticks 
so exECtly, in colour, in the small rugosities of the bark, in the 
knots and small branches, imitated by the joints of the legs 
which are either pressed close to the body, or stuck out at 
random, that it is absolutely impossible, by the eye alone, to 
distinguish the real dead twigs which fall down from the trees 
overhead, from the living insects. The writer has often looked 
at them in doubt, and has been obliged to use the sense of 
touch to determine the point. Some are small and slender 
like the most delicate twigs ; others again have wings, and it 
is curious that these are often beautifully coloured, generally 
bright pink, sometimes yellow, and sometimes finely banded 
with black ; but when at rest the wings fold up so as to be 
completely concealed under the narrow wing-covers, and the 



288 TROPICAL NATURE 



whole insect is then green or brown, and almost invisible 
among the twigs or foliage. To increase the resemblance to 
vegetation, some of these Phasmas have small green processes 
in various parts of their bodies looking exactly like moss. 
These inhabit damp forests both in the Malay islands and in 
America, and they are so marvellously like moss-grown twigs 
that the closest examination is needed to satisfy oneself that 
it is really a living insect we are looking at. 

Many of the locusts are equally well-disguised, some re- 
sembling green leaves, others those that are brown and dead ; 
and the latter often have small transparent spots on the wings, 
looking like holes eaten through them. That these disguises 
deceive their natural enemies is certain, for otherwise the 
Phasmidae would soon be exterminated. They are large and 
sluggish, and very soft and succulent ; they have no means of 
defence or of flight, and they are eagerly devoured by numbers 
of birds, especially by the numerous cuckoo tribe, whose 
stomachs are often full of them ; yet numbers of them escape 
destruction, and this can only be due to their vegetable 
disguises. Mr. Belt records a curious instance of the actual 
operation of this kind of defence in a leaf -like locust, which 
remained perfectly quiescent in the midst of a host of insecti- 
vorous ants, which ran over it without finding out that it was an 
insect and not a leaf ! It might have flown away from them, 
but it would then instantly have fallen a prey to the numerous 
birds which always accompany these roaming hordes of ants 
to feed upon the insects that endeavour to escape. Par more 
conspicuous than any of these imitative species are the large 
locusts, with rich crimson or blue-and-black spotted wings. 
Some of these are nearly a foot in expanse of wings ; they 
fly by day, and their strong spiny legs probably serve as a 
protection against all the smaller birds. They cannot be 
said to be common ; but when met with they fully satisfy our 
notions as to the large size and gorgeous colovu'S of tropical 
insects.^ 



Considering the enormous numbers and endless variety 
of the beetle tribe that are known to inhabit the tropics, they 

' It has now teen ascertained that these conspicuously coloured locusts are 
protected by inedibility. See Darwinism, p. 267. 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 289 

form by no means so prominent a feature in the animal life 
of the equatorial zone as we might expect. Almost every 
entomologist is at first disappointed with them. He finds that 
they have to be searched for almost as much as at home, 
while those of large size (except one or two very common 
species) are rarely met with. The groups which most attract 
attention, from their size and beauty, are the Buprestidse and 
the Longicorns. The former are usually smooth insects of an 
elongate ovate form, with very short legs and antennae, and 
adorned with the most glowing metallic tints. They abound 
on fallen tree-trunks and on foliage, in the hottest sunshine, 
and are among the most briUiant ornaments of the tropical 
forests. Some parts of the temperate zone, especially Aus- 
tralia and Chili, abound in Buprestidae which are equally 
beautiful ; but the largest species are only found within the 
tropics, those of the Malay islands being the largest of aU. 

The Longicorns are elegantly shaped beetles, usually with 
long antennae and legs, varied in form and structure in an 
endless variety of ways, and adorned with equally varied 
colours, spots, and markings. Some are large and massive 
insects three or four inches long, while others are no bigger 
than our smaller ants. The majority have sober colours, but 
often delicately marbled, veined, or spotted ; while others are 
red, or blue, or yeUow, or adorned with the richest metallic 
tints. Their antennae are sometimes excessively long and 
graceful, often adorned with tufts of hair, and sometimes 
pectinated. They especially abound where timber trees have 
been recently felled in the primeval forests ; and while ex- 
tensive clearings are in progress their variety seems endless. 
In such a locality in the island of Borneo, nearly 300 dijGFerent 
species were found during one dry season, while the number 
obtained during eight years' collecting in the whole Malay 
Archipelago was about a thousand species. 

Among the beetles that always attract attention in the tropics 
are the large, horned Copridae and Dynastidae, corresponding 
to our dung-beetles. Some of these are of great size, and 
they are occasionally very abundant. The immense horn-Hke 
protuberances on the head and thorax of the males in some of 
the species are very extraordinary, and, combined with then- 
polished or rugose metallic colours, render them perhaps the 

V 



290 TROPICAL NATURE 



most conspicuous of all the beetle tribe. The weevils and 
their allies are also very interesting, from their immense 
numbers, endless variety, and the extreme beauty of many of 
the species. The Anthribidse, which are especially abundant 
in the Malay Archipelago, rival the Longicorns in the immense 
length of their elegant antennae ; while the diamond beetles of 
Brazil, the Eupholi of the Papuan islands, and the Pachy- 
rhynchi of the Philippines, are veritable living jewels. 

Where a large extent of virgin forest is cut down in the 
early part of the dry season, and some hot sunny weather 
follows, the abundance and variety of beetles attracted by the 
bark and foliage in various stages of drying is amazing. The 
air is filled with the hum of their wings. G-olden and green 
Buprestidee are flying about in every direction, and settling 
on the bark in full sunshine. Green and spotted rose-chafers 
hum along near the ground ; long -horned Anthribidse are 
disturbed at every step ; elegant little Longicorns circle 
about the drying foliage, while larger species fiy slowly 
from branch to branch. Every fallen trunk is full of life. 
Strange mottled, and spotted, and rugose Longicorns, endless 
Curculios, queer -shaped Brenthidse, velvety brown or steel- 
blue Cleridae, brown or yellow or whitish click beetles 
(Elaters), and brilliant metallic Carabidse. Close by, in 
the adjacent forest, a whole host of new forms are found. 
Elegant tiger-beetles, leaf-hunting Carabidae, musk-beetles of 
many sorts, scarlet Telephori, and countless Chrysomelas, 
Hispas, Coccinellas, with strange Heteromera, and many curious 
species which haunt fungi, rotten bark, or decaying leaves. 
With such variety and beauty the most ardent entomologist 
must be fully satisfied ; and when, every now and then, some 
of the giants of the tropics fall in his way — grand Prionidse or 
Lamiidse several inches long, a massive golden Buprestis, or a 
monster horned Dynastes — he feels that his most exalted 
notions of the insect-life of the tropics are at length realised. 

Wingless Insects 

Passing on to other orders of insects, the hemiptera 

dragon -flies and true flies hardly call for special remark. 

Among them are to be found a fair proportion of large and 

handsome species, but they require much searching after in 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 291 

their special haunts, and seldom attract so much attention as 
the groups already referred to. More prominent are the 
wingless tribes, such as spiders, scorpions, and centipedes. 
The wanderer in the forest often finds the path closed by large 
webs almost as strong as silk, inhabited by gorgeous spiders 
with bodies nearly two inches long and legs expanding six 
inches. Others are remarkable for their hard flat bodies, 
terminating in horned processes which are sometimes long, 
slender, and curved Hke a pair of miniature cow's horns. 
Hairy terrestrial species of large size are often met with, the 
largest belonging to the South American genus Mygale, which 
sometimes actually kill birds, a fact which had been stated 
by Madame Merian and others, but was discredited till 
Mr. Bates succeeded in catching one in the act. The small 
jumping spiders are also noticeable from their immense 
numbers, variety, and beauty. They frequent foHage and 
flowers, running about actively in pursuit of small insects; 
and many of them are so exquisitely coloured as to resemble 
jewels rather than spiders. Scorpions and centipedes make 
their presence known to every traveller. In the damp 
forests of the Malay islands are huge scorpions of a greenish 
colour and eight or' ten inches long ; while in huts and houses 
smaller species lurk under boxes and boards, or secret them- 
selves in almost every article not daily examined. Centipedes 
of immense size and deadly venom harbour in the thatch of 
houses and canoes, and will even ensconce themselves under 
pillows and in beds, rendering a thorough examination 
necessary before retiring to rest. Yet with moderate pre- 
cautions there is little danger from these disgusting insects, as 
may be judged by the fact that diuring twelve years' wander- 
ings in American and Malayan forests the author was never 
once bitten or stimg by them. 

General Observations on Tropical Insects 

The characteristics of tropical insects that will most attract 
the ordinary traveller are, their great numbers, and the 
large size and brilliant colours often met with. But a more 
extended observation leads to the conclusion that the average 
of size is probably but little greater in tropical than in 
temperate zones, and that, to make up for a certain propor- 



292 TROPICAL NATURE in 

tion of very large, there is a corresponding increase in the 
numbers of very small species. The much greater size reached 
by many tropical insects is no doubt due to the fact that the 
supply of food is always in excess of their demands in the 
larva state, while there is no check from the ever-recurring 
cold of winter ; and they are thus able to acquire the dimen- 
sions that may be on the whole most advantageous to the race, 
unchecked by the annual or periodical scarcities which in less 
favoured climates would continually threaten their extinction. 
The colours of tropical insects are, probably, on the average 
more brilliant than those of temperate countries, and some of 
the causes which may have led to this have been discussed in 
another part of this volume. ^ It is in the tropics that we 
find, most largely developed, whole groups of insects which 
are unpalatable to almost all insectivorous creatures, and it is 
among these that some of the most gorgeous colours prevail. 
Others obtain protection in a variety of ways; and the 
amount of cover or concealment always afforded by the 
luxuriant tropical vegetation is probably a potent agent in 
permitting a full development of colour. 

Birds 

Although the number of briUiantly-coloured birds in almost 
every part of the tropics is very great, yet they are by no 
means conspicuous, and as a rule they can hardly be said to 
add much to the general effect of equatorial scenery. The 
traveller is almost always disappointed at first with the birds, 
as he is with the flowers and the beetles ; and it is only when, 
gun in hand, he spends days in the forest, that he finds out 
how many beautiful living things are concealed by its dense 
foliage and gloomy thickets. A considerable number of the 
handsomest tropical birds belong to family groups which are 
confined to one continent with its adjacent islands, and we 
shall therefore be obliged to deal for the most part with such 
large divisions as tribes and orders, by means of which to 
define the characteristics of tropical bird-life. We find that 
there are three important orders of birds which, though by 
no means exclusively tropical, are yet so largely developed 
there in proportion to their scarcity in extra-tropical regions, 

^ Chapters v. and vi.,jiost. The Colowrs of Animals and Plants. 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 293 

that, more than any others, they serve to give a special char- 
acter to equatorial ornithology. These are the Parrots, the 
Pigeons, and the Picarise, to each of which groups we will 
devote some attention. 

Parrots 

The parrots, forming the order Psittaci of naturalists, are 
a remarkable group of fruit-eating birds, of such high and 
peculiar organisation that they are often considered to stand 
at the head of the entire class. They are pre-emintently 
characteristic of the intertropical zone, being nowhere absent 
within its limits (except from absolutely desert regions), and 
they are generally so abundant and so conspicuous as to 
occupy among birds the place assigned to butterflies among 
insects. A few species range far into the temperate zones. 
One reaches CaroHna in North America, another the Magellan 
Straits in South America ; in Africa they only extend a few 
degrees beyond the southern tropic ; in North- Western India 
they reach 35° north latitude, but in the Australian region 
they range farthest towards the pole, being found not only in 
New Zealand, but as far as the Macquarie islands in 54° 
south, where the climate is very cold and boisterous, but 
sufficiently uniform to supply vegetable food throughout the 
year. There is hardly any part of the equatorial zone in 
which the traveller will not soon have his attention called to 
some members of the parrot tribe. In Brazil the great blue 
and yellow or crimson macaws may be seen every evening 
wending their way homeward in pairs, almost as commonly 
as rooks with us, while innumerable parrots and parraquets 
attract attention by their harsh cries when disturbed from 
some favourite fruit-tree. In the Moluccas and New Guinea 
white cockatoos and gorgeous lories in crimson and blue are 
the very commonest of birds. 

No group of birds — ^perhaps no other group of animals — 
exhibits within the same limited number of genera and species " 
so wide a range and such an endless variety of colour. As a 
rule, parrots may be termed green birds, the majority of the 
species having this colour as the basis of their plumage 
relieved by caps, gorgets, bands, and wing-spots of other and 
brighter hues. Yet this general green tint sometimes changes 



294 TROPICAL KATURE tli 

into light or deep blue, as in some macaws j into pure yellow 
or ricli orange, as in some of the American macaw -parrots 
(Conurus); into purple, gray, or dove-colour, as in some 
American, African, and Indian species ; into the purest crim- 
son, as in some of the lories ; into rosy-white and pure white, 
as in the cockatoos ; and into a deep purple, ashy, or black, 
as in several Papuan, Australian, and Mascarene species. 
There is, in fact, hardly a single distinct and definable coloiu- 
that cannot be fairly matched among the 400 species of 
known parrots. Their habits, too, are such as to bring them 
prominently before the eye. They usually feed in flocks; 
they are noisy, and so attract attention ; they love gardens, 
orchards, and open sunny places ; they wander about far in 
search of food, and towards sunset return homewards in noisy 
flocks, or in constant pairs. Their forms and motions are 
often beautiful and attractive. The immensely long tails of 
the macaws, and the more slender tails of the Indian parra- 
quets ; the fine crest of the cockatoos ; the swift flight of 
many of the smaller species, and the graceful motions of the 
little love-birds and allied forms, together with their affec- 
tionate natures, aptitude for domestication,' and powers of 
mimicry — combine to render them at once the most con- 
spicuous and the most attractive of all the specially tropical 
forms of bird-life. 

The number of species of parrots found in the different 
divisions of the tropics is very unequal. Africa is by far the 
poorest; since along with Madagascar and the Mascarene 
Islands, which have many peculiar forms, it scarcely numbers 
two dozen species. Asia, along with the Malay islands as far 
as Java and Borneo, is also very poor, with about thirty 
species. Tropical America is very much richer, possessing 
about 140 species, among which are many of the largest and 
most beautiful forms. But of all parts of the globe the 
tropical islands belonging to the Australian region (from 
Celebes eastward), together with the tropical parts of Australia, 
are richest in the parrot tribe, possessing more than 150 species, 
among which are many of the most remarkable and beautiful 
of the entire group. The whole Australian region, whose 
extreme limits may be defined by Celebes, the Marquesas, and 
the New Zealand group, possesses over 200 species of parrots. 



ANIMAL LIFE IN THE TROPICAL FORESTS 295 



These are such common birds in all temperate countries 
that it may surprise many readers to learn that they are 
nevertheless a characteristic tropical group. That such is the 
case, however, will be evident from the fact that only sixteen 
species are known from the whole of the temperate parts of 
Europe, Asia, and North America, while about 330 species 
inhabit the tropics. Again, the great majority of the species 
are found congregated in the equatorial zone, whence they 
diminish gradually toward the limits of the tropics, and then 
suddenly faU oif in the temperate zones. Yet although they 
are pre-eminently tropical or even equatorial as a group, they 
are not, from our present point of view, of much importance, 
because they are so shy and so generally inconspicuous that 
in most parts of the tropics an ordinary observer might hardly 
be aware of their existence. The remark applies especially to 
America and Africa, where they are neither very abundant 
nor peculiar ; but in the Eastern hemisphere, and especially 
in the Malay Archipelago and Pacific islands, they occur in 
such profusion and present such singular forms and brilliant 
colours, that they are sure to attract attention. Here we 
find the extensive group of fruit -pigeons, which, in their 
general green colours adorned with patches and bands of 
purple, white, blue, or orange, almost rival the paiTot tribe ; 
while the golden-green Nicobar pigeon, the great crowned 
pigeons of New Guinea as large as turkeys, and the golden- 
yellow fruit-dove of the Fijis, can hardly be surpassed for beauty. 

Pigeons are especially abundant and varied in tropical 
archipelagoes, so that if we take the Malay and Pacific islands, 
the Madagascar group, and the Antilles or West Indian 
islands, we find that they possess between them more difierent 
kinds of pigeons than all the continental tropics combined. 
Yet further, that portion of the Malay Archipelago east of 
Borneo, together with the Pacific islands, is exceptionally 
rich in pigeons; and the reason seems to be that monkeys 
and all other arboreal mammals that devour eggs and young 
birds are entirely absent from this region. Even in South 
America pigeons are scarce where monkeys are abundant, and 
vice versA, so that here we seem to get a glimpse of one of the 



296 TROPICAL NATURE 



curious interactions of animals on each other, by which their 
distribution, their habits, and even their colours, may have 
been influenced, for the most conspicuous pigeons, whether by 
colour or by their crests, are all found in countries where 
they have the fewest enemies. 

Pica/rice 

The extensive and heterogeneous series of bird till recently 
comprised under this term includes most of the fissirostral 
and scansorial groups of the older naturalists. They may be 
described as, for the most part, arboreal birds, of a low grade 
of organisation, with weak or abnormally developed feet, and 
usually less active than the true Passeres or perching birds of 
which our warblers, finches, and crows may be taken as the 
types. The order Picarise comprises twenty-five families, some 
of which are very extensive. AH are either wholly or mainly 
tropical, only two of the families — the woodpeckers and the 
kingfishers — having a few representatives which are per- 
manent residents in the temperate regions, while our summer 
visitor, the cuckoo, is the sole example in Northern Europe 
of one of the most abimdant and widespread tropical families 
of birds. Only four of the families have a general distribu- 
tion over all the warmer countries of the globe — the cuckoos, 
the kingfishers, the swifts, and the goatsuckers; while two 
others — the trogons and the woodpeckers — are only wanting 
in the Australian region, ceasing suddenly at Borneo and 
Celebes respectively. 

Cuckoos 
Whether we consider their wide range, their abundance in 
genera and species, or the peculiarities of their organisation, 
the cuckoos may be taken as the most typical examples of this 
extensive order of birds ; and there is perhaps no part of the 
tropics where they do not form a prominent feature in the 
ornithology of the country. Their chief food consists of soft 
insects, such as caterpillars, grasshoppers, and the defenceless 
stick- and leaf-insects ; and in search after these they frequent 
the bushes and lower parts of the forest, and the more open 
tree-clad plains. They vary greatly in size and appearance, 
from the small and beautifully metallic golden- cuckoos of 



m ANIMAL LIFE IN THE TROPICAL FORESTS 297 

Africa, Asia, and Australia, no larger than sparrows, to the 
pheasant-like ground cuckoo of Borneo, the Scythrops of the 
Moluccas, which almost resembles a hornbill, the Ehamp- 
hococcyx of Celebes with its richly- coloured bill, and the 
Goliath cuckoo of Gilolo with its enormously long and ample 
tail. 

Cuckoos, being invariably weak and defenceless birds, 
conceal themselves as much as possible among foliage or 
herbage; and as a further protection, many of them have 
acquired the coloration of rapacious or combative birds. In 
several parts of the world cuckoos are coloured exactly like 
hawks, while some of the small Malayan cuckoos closely 
resemble the pugnacious drongo-shrikes. 

Trogms, Barbels, Toucans, and Eornbills 

Many of the families of Picariae are confined to the tropical 
forests, and are remarkable for their varied and beautiful 
colouring. Such are the trogons of America, Africa, and 
Malaya, whose dense pufiy plumage exhibits the purest tiats 
of rosy-pink, yellow, and white, set ofi" by black heads and a 
golden-green or rich brown upper surface. Of more slender 
forms, but hardly less brilliant in colour, are the jacamars and 
motmots of America, with the bee-eaters and rollers of the 
East, tie latter exhibiting tints of pale-blue or verditer-green, 
which are very unusual. The barbets are rather clumsy fruit- 
eating birds, found in all the great tropical regions except that 
of the Austro- Malay islands, and they exhibit a wonderful 
variety as well as strange combinations of colours. Those of 
Asia and Malaya are mostly green, but adorned about the 
head and neck with patches of the most vivid reds, blues, and 
yellows in endless combinations. The African species are 
usually black or greenish-black, with masses of intense crim- 
son, yellow, or white, mixed in various proportions and 
patterns ; while the American species combine both styles of 
colouring, but the tints are usually more delicate, and are 
often more varied and more harmoniously interblended. In 
the Messrs. Marshall's fine work ^ all the species are described 
and figured, and few more instructive examples can be found 

1 A Monograph of the Capitonidee or Scansorial Barbets, by C. F. T. 
Marshall and G. F. L. Marsliall. 1 871. 



298 TROPICAL NATURE ni 

than are exhibited in their beautifully-coloured plates, of the 
endless ways in which the most glaring and inharmonious 
colours are often combined in natural objects with a generally 
pleasing result. 

We will next group together three families which, although 
quite distinct, may be said to represent each other in their 
respective countries, — the toucans of America, the plantain- 
eaters of Africa, and the hornbiUs of the East, — ^aU being 
large and remarkable birds, and certain to attract the tra- 
veller's attention. The toucans are the most beautiful on 
account of their large and richly-coloured bills, their delicate 
breast-plumage, and the varied bands of colour with which 
they are often adorned. Though feeding chiefly on fruits, 
they also devour birds' eggs and young birds ; and they are 
remarkable for the strange habit of sleeping with the tail laid 
flat upon their backs, in what seems a most unnatural and 
inconvenient position. What can be the use of their enor- 
mous bills has been a great puzzle to naturalists, the only 
tolerably satisfactory solution yet arrived at being that sug- 
gested by Mr. Bates, — that it simply enables them to reach 
fruit at the ends of slender twigs which, owing to their weight 
and clumsiness, they would otherwise be unable to obtain. 
At first sight it appears very improbable that so large and 
remarkable an organ should have been developed for such a 
purpose; but we have only to suppose that the original 
toucans had rather large and thick bills, not unlike those of 
the barbets (to which group they are undoubtedly allied), and 
that as they increased in size and required more food, only 
those could obtain a sufficiency whose unusually large beaks 
enabled them to reach farthest. So large and broad a bill as 
they now possess would not be required; but the develop- 
ment of the bill naturally went on as it had begun, and, so 
that it was light and handy, the large size was no disadvantage 
if length was obtained. The plantain-eaters of Africa are less 
remarkable birds, though adorned with rich colours and 
elegant crests. The hornbills, though less beautiful than the 
toucans, are more curious, from the strange forms of their 
huge bills, which are often adorned with ridges, knobs, or 
recurved horns. They are bulky and heavy birds, and during 
flight beat the air with prodigious force, producing a rushing 



lit Al^lMAL LIFE IN TSE TROPICAL SOEESTS 299 

sound very like the puff of a locomotive, and whicli can some- 
times be heard a mile off. They mostly feed on fruits ; and 
as their very short legs render them even less active than the 
toucans, the same explanation may be given of the large size 
of their bills, although it will not account for the curious 
horns and processes from which they derive their distinctive 
name. The largest hornbills are more than four feet long, 
and their laboured noisy flight and huge bills, as well as their 
habit of perching on the top of bare or isolated trees, render 
them very conspicuous objects. 

The Picarise comprise many other interesting families — 
as, for example, the puif-birds, the todies, and the humming- 
birds ; but as these are all confined to America we can hardly 
claim them as characteristic of the tropics generally. Others, 
though very abundant in the tropics, like the kingfishers and 
the goatsuckers, are too well known in temperate lands to 
allow of their being considered as specially characteristic of 
the equatorial zone. We will therefore pass on to consider 
what are the more general characteristics of the tropical as 
compared with the temperate bird-faima, especially as exem- 
plified among the true perchers or Passeres, which constitute 
about three-fourths of all terrestrial birds. 



This great order comprises all our most familiar birds, 
such as the thrushes, warblers, tits, shrikes, flycatchers, 
starlings, crows, wagtails, larks, and finches. ' These families 
are all more or less abundant in the tropics ; but there are 
a number of other families which are almost or quite peculiar 
to tropical lands and give a special character to their bird- 
life. AH the peculiarly tropical families are, however, con- 
fined to some definite portion of the tropics, a number of 
them being American only, others Australian, while others 
again are common to all the warm countries of the Old 
World ; and it is a curious fact that there is no single family of 
this great order of birds that is common to all tropical regions 
and confined to them, or that is even especially characteristic 
of the tropical zone, like the cuckoos among the Picarise. 
The tropical families of passerine birds being very numerous, 
and their peculiarities not easily understood by any but orni- 



300 TROPICAL NATUEE 



thologists, it will, be better to consider the series of fifty- 
families of Passeres as one compact group, and endeavour to 
point out -what external peculiarities are most distinctive of 
those which inhabit tropical countries. 

Owing to the prevalence of forests and the abundance of 
flowers, fruits, and insects, tropical and especially equatorial 
birds have become largely adapted to these kinds of food ; 
while the seed-eaters, which abound in temperate lands where 
grasses cover much of the surface, are proportionately scarce. 
Many of the peculiarly tropical families are therefore either 
true insec1>eaters or true frui1>eaters, whereas in the tem- 
perate zones a mixed diet is more general. 

One of the features of tropical birds that will first strike 
the observer is the prevalence of crests and of ornamental 
plumage in various parts of the body, and especially of ex- 
tremely long or curiously shaped feathers in the tails, tail- 
coverts, or wings of a variety of species. As examples we 
may refer to the red paradise-bird, whose middle tail-feathers 
are like long ribands of whalebone ; to the wire-like tail 
feathers of the king bird-of-paradise of New Guinea, and of 
the wire-tailed manakin of the Amazons; and to the long 
waving tail plumes of the whydah finch of West Africa and 
paradise flycatcher of India,; to the varied and elegant crests 
of the cock-of-the-rock, the king-tyrant, the umbrella-bird, 
and the six-plumed bird-of-paradise; and to the wonderful 
side plumes of most of the true paradise-birds. In other 
orders of birds we have such remarkable examples as the 
racquet-tailed kingfishers of the Moluccas, and the racquets 
tailed parrots of Celebes ; the enormously developed tail- 
coverts of the peacock and the Mexican trogon; and the 
excessive wing-plumes of the argus-pheasant of Malacca and 
the long-shafted goatsucker of West Africa. 

Still more remarkable are the varied styles of, coloration 
in the birds of tropical forests, which rarely or never appear 
in those of temperate lands. We have intensely lustrous 
metallic plumage in the jacamars, trogons, humming-birds, 
sun-birds, and paradise-birds ; as well as in some starlings, 
pittas or ground thrushes, and drongo-shrikes. Pure green 
tints occur in parrots, pigeons, green bulbuls, greenlets, and 
in some tanagers, finches, chatterers, and pittas. These 



m ANIMAL LIFE IN THE TROPICAL FORESTS 301 

undoubtedly tend to concealment; but we have also the 
strange phenomenon of white forest birds in the tropics, a 
colour only found elsewhere among the aquatic tribes and in 
the arctic regions. Thus, we have the beU-bird of South 
America, the white pigeons and cockatoos of the East, with 
a few starlings, woodpeckers, kingfishers, and goatsuckers, 
which are either very light - coloured or in great part pure 
white. 

But besides these strange and new and beautiful forms 
of bird life, which we have attempted to indicate as charac- 
terising the tropical regions, the traveller will soon find that 
there are hosts of dull and dingy birds, not one whit different, 
so far as colour is concerned, from the sparrows, warblers, 
and thrushes of our northern climes. He will, however, if 
observant, soon note that most of these dull colours are pro- 
tective; the groups to which they belong frequenting low 
thickets, or the ground, or the trunis of trees. He wUl find 
groups of birds specially adapted to certain modes of tropical 
life. Some live on ants upon the ground, others pick minute 
insects from the bark of trees ; one group will devour bees 
and wasps, others prefer caterpillars; while a host of small 
birds seek for insects in the corollas of flowers. The air, the 
earth, the undergrowth, the tree-trunks, the flowers, and the 
fruits, all support their specially adapted tribes of birds. 
Each species fills a place in nature, and can only continue to 
exist so long as that place is open to it ; and each has become 
what it is in every detail of form, size, structure, and even of 
colour, because it has inherited through countless ancestral 
forms all those variations which have best adapted it among 
its fellows to fill that place, and to leave behind it equally 
well adapted successors. 

REPTILES AND AMPHIBIA 

Next to the birds, or perhaps to the less observant eye 
even before them, the abundance and variety of reptiles form 
the chief characteristic of tropical nature; and the three 
groups — Uzards, snakes, and frogs — comprise all that, from 
our present point of view, need be noticed. 



302 TROPICAL NATURE 



Limrds 

Lizards are by far the most abundant in individuals and 
the most conspicuous; and they constitute one of the first 
attractions to the visitor from colder lands. They literally 
swarm everywhere. In cities they may be seen running 
along walls and up palings ; sunning themselves on logs of 
wood, or creeping up to the eaves of cottages. In every 
garden, road, or dry sandy path, they scamper aside as you 
walk along. They crawl up trees, keeping at the farther side 
of the trunk and watching the passer-by with the caution of 
a squirrel. Some wiU walk up smooth walls with the greatest 
ease; while in houses the various kinds of Geckos cling to 
the ceilings, along which they run back downwards in pursuit 
of flies, holding on by means of their dUated toes with 
suctorial discs, though sometimes, losing hold, they fall upon 
the table or on the upturned face of the visitor. In the 
forests large, flat, and marbled Geckos cling to the smooth 
trunks ; small and active lizards rest on the foliage ; while 
occasionally the larger kinds, three or four feet long, rustle 
heavily as they move among the fallen leaves. 

Their colours vary much, but are usually in harmony with 
their surroundings and habits. Those that climb about walls 
and rocks are stone -coloured, and sometimes nearly black; 
the house lizards are gray or pale -ashy, and are hardly 
visible on a palm -leaf thatch, or even on a white -washed 
ceiling. In the forest they are often mottled with ashy-green, 
like lichen -grown bark. Most of the ground - lizards are 
yellowish or brown ; but some are of beautiful green colours, 
with very long and slender tails. These are among the most 
active and lively; and instead of crawling on their bellies 
like many lizards, they stand well upon their feet and 
scamper about with the agility and vivacity of kittens. 
Their tails are very brittle ; a slight blow causing them to 
snap off, when a new one grows, which is, however, not 
so perfectly formed and completely scaled as the original 
member. It is not uncommon, when a tail is half broken, 
for a new one to grow out of the wound, producing the 
curious phenomenon of a forked tail. There are about 1300 
different kinds of lizards known, the great majority of which 



in ANIMAL LIFE IN THE TROPICAL FORESTS 303 

inhabit the tropics, and they probably increase in numbers 
towards the equator. A rich vegetation and a due propor- 
tion of moisture and sunshine seem favourable to them, as 
shown by their great abundance and their varied kinds at 
Para and in the Aru islands — places which are nearly the 
antipodes of each other, but which both enjoy the fine equa- 
torial climate in perfection, and are alike pre-eminent in the 
variety and beauty of their insect life. 

Three peculiar forms of lizard may be mentioned as 
specially characteristic of the American, African, and Asiatic 
tropical zones respectively. The iguanas of South America 
are large, arboreal, herbivorous lizards of a beautiful green 
colour, which renders them almost invisible when resting 
quietly among foliage. They are distinguished by the- 
serrated back, deep dew-lap, and enormously long tail, and 
are one of the few kinds of lizards whose flesh is considered 
a delicacy. The chameleons of Africa are also arboreal 
lizards, and they have the prehensile tail, which is more 
usually found among American animals. They are excessively 
slow in their motions, and are protected by the wonderful 
power of changing their colour so as to assimilate it with 
that of immediately surrounding objects. Like the majority 
of lizards they are insectivorous, but they are said to be 
able to live for months without taking food. The dragons 
or flying lizards of India and the larger Malay islands are 
perhaps the most curious and interesting of living reptiles, 
owing to their power of passing through the air by means of 
wing-like membranes, which stretch along each side of the 
body and are expanded by means of slender bony processes 
from the first six false ribs. These membranes are folded 
up close to the body when not in use, and are then almost 
imperceptible ; but when open they form a nearly circular 
web, the upper surface of which is generally zoned with red 
or yeUow in a highly ornamental manner. By means of this 
parachute the animal can easily pass from one tree to another 
for a distance of about thirty feet, descending at first, but as it 
approaches its destination rising a little so to reach the tree 
with its head erect. They are very small, being usually 
not more than two or three inches long, exclusive of the 
slender tail ; and when the wings are expanded in the sun- 



304 TROPICAL NATURE HI 

shine they more resemble some strange insects than members 
of the reptile tribe. 

Snakes 

Snakes are, fortunately, not so abundant or so obtrusive as 
lizards, or the tropics would be scarcely habitable. At first, 
indeed, the traveller is disposed to wonder that he does not see 
more of them, but he will soon find out that there are plenty ; 
and, if he is possessed by the usual horror or dislike of them, 
he may think there are too many. In the equatorial zone 
snakes are less troublesome than in the drier parts of the 
tropics, although they are probably more numerous and 
more varied. This is because the country is naturally a 
vast forest, and the snakes being all adapted to a forest 
life do not as a rule frequent gardens and come into houses 
as in India and Australia, where they are accustomed to open 
and arid places. One cannot traverse the forest, however, 
without soon coming upon them. The slender green whip- 
snakes glide among the foliage, and may often be touched 
before they are seen. The ease and rapidity with which 
these snakes pass through bushes, almost without disturbing 
a leaf, is very curious. More dangerous are the green vipers, 
which lie coiled motionless upon foliage, where their colour 
renders it difficult to see them. The writer has often come 
upon them while creeping through the jungle after birds or 
insects, and has sometimes only had time to draw back when 
they were within a few inches of his face. It is startling in 
walking along a forest path to see a long snake glide away 
from just where you were going to set down your foot ; but 
it is perhaps even more alarming to hear a long-drawn heavy 
slur-r-r, and just to catch a glimpse of a serpent as thick as 
your leg and an unknown number of feet in length, showing 
that you must have passed unheeding within a short dis- 
tance of where it was lying. The smaller pythons are not, 
however, dangerous, and they often enter houses to catch and 
feed upon the rats, and are rather liked by the natives. You 
will sometimes be told when sleeping in a native house that 
there is a large snake in the roof, and that you need not be 
disturbed in case you should hear it hunting after its prey. 
These serpents no doubt sometimes grow to an enormous 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 305 

size, but such monsters are rare. In Borneo, Mr. St. John 
states that he measured one twenty-six feet long, probably 
the largest ever measured by a European in the East. The 
great water -boa of South America is believed to reach the 
largest size. Mr. Bates measured skins twenty-one feet long, 
but the largest ever met with by a European appears to be 
that described by the botanist. Dr. Gardiner, in his Travels in 
Brazil. It had devoured a horse, and was found dead, en- 
tangled in the branches of a tree overhanging a river, into 
which it had been carried by a flood. It was nearly forty 
feet long. These creatures are said to seize and devour full- 
sized cattle on the Eio Branco ; and from what is known of 
their habits'this is by no means improbable. 

Frogs and Toads 

The only Amphibia that often meet the traveller's eye in 
equatorial countries are the various kinds of frogs and toads, 
and especially the elegant tree-frogs. When the rainy season 
begins, and dried-up pools and ditches become filled with 
water, there is a strange nightly concert produced by the 
frogs, some of which croak, others bellow, while many have 
clanging or chirruping, and not unmusical notes. In roads 
and gardens one occasionally meets huge toads six or seven 
inches long ; but the most abundant and most interesting of 
the tribe are those adapted for an arboreal life, and hence 
called tree-frogs. Their toes terminate in discs, by means of 
which they can cling firmly to leaves and stems. The majority 
of them are green or brown, and these usually feed at night, 
sitting quietly during the day so as to be almost invisible, 
owing to their colour and their moist shining skins so closely 
resembling vegetable surfaces. Many are beautifully marbled 
and spotted, and when sitting on leaves resemble large beetles 
more than frogs, while others are adorned with bright and 
staring colours ; and these, as Mr. Belt has discovered, have 
nauseous secretions which render them uneatable, so that they 
have no need to conceal themselves. Some of these are bright 
blue, others are adorned with yellow stripes, or have a red 
body with blue legs. Of the smaller tree-frogs of the tropics 
there must be hundreds of species still unknown to naturalists. 



806 TROPICAL NATURE Iti 

Mammalia 
Monheys 

The highest class of animals, the Mammalia, although 
sufficiently abundant in all equatorial lands, are those 
which are least seen by the traveller. There is, in fact, 
only one group — the monkeys — which are at the same time 
pre-eminently tropical, and which make themselves perceived 
as one of the aspects of tropical nature. They are to be met 
with in all the great continents and larger islands, except 
Australia, NewGuinea, and Madagascar, though the latter island 
possesses the lower allied form of Lemurs ; and they never 
fail to. impress the observer with a sense of the exuberant 
vitality of the tropics. They are pre-eminently arboreal in 
their mode of life, and are consequently most abundant and 
varied where vegetation reaches its maximum development. 
In the East we find that maximum in Borneo, and in the 
West African forests ; while in the West the great forest 
plain of the Amazon stands pre-eminent. It is near the 
equator only that the great Anthropoid apes, the gorilla, 
chimpanzee, and orang-utan are found, and they may be met 
with by any persevering explorer of the jungle. The gibbons, 
or long-armed apes, have a wider range in the Asiatic con- 
tinent and in Malaya, and they are more abundant both in 
species and individuals. Their plaintive howling notes may 
often be heard in the forests, and they are constantly to be 
seen sporting at the summits of the loftiest trees, swinging 
suspended by their long arms, or bounding from tree to tree 
with incredible agility. They pass through the forest at a 
height of a hundred feet or more, as rapidly as a deer will 
travel along the ground beneath them. Other monkeys of 
various kinds are more abundant and usually less shy ; and in 
places where firearms are not much used they will approach 
the houses and gambol in the trees undisturbed by the 
approach of man. The most remarkable of the tailed monkeys 
of the East is the proboscis monkey of Borneo, whose long 
fleshy nose gives it an aspect very different from that of most 
of its allies. 

In tropical America monkeys are even more abundant 
than in the East, and they present many interesting pecu- 



ni ANIMAL LIFE IN THE TROPICAL FORESTS 30? 

liarities. They differ somewliat in dentition and in other 
structural features from all Old World apes, and a consider- 
able number of them have prehensile tails, a peculiarity never 
found elsewhere. In the howlers and the spider monkeys 
the tail is very long and powerful, and by twisting the 
extremity round a branch the animal can hang suspended as 
easily as other monkeys can by their hands. It is, in fact, a 
fifth hand, and is constantly used to pick up small objects 
from the ground. The most remarkable of the American 
monkeys are the howlers, whose tremendous roaring exceeds 
that of the lion or the bull, and is to be heard frequently at 
morning and evening in the primeval forests. The sound is 
produced by means of a large, thin, bony vessel in the throat, 
into which air is forced ; and it is very remarkable that this 
one group of monkeys should possess an organ not found in 
any other monkey or even in any other mammal, apparently 
for no other purpose than to be able to make a louder noise 
than the rest. The only other monkeys worthy of special 
attention are the marmosets, beautiful little creatures with 
crests, whiskers, or manes, in outward form resembling squirrels, 
but with a very small monkey -like face. They are either 
black, brown, reddish, or nearly white in colour, and are the 
smallest of the monkey tribe, some of them being only about 
six inches long exclusive of the tail. 

Bats 
Almost the only other order of mammals that is specially 
and largely developed in the tropical zone is that of the 
Chiroptera or bats, which becomes suddenly much less plenti- 
ful when we pass into the temperate regions, and still more 
rare towards the colder parts of it, although a few species 
appear to reach the Arctic circle. The characteristics of the 
tropical bats are their great numbers and variety, their large 
size, and their peculiar forms or habits. In the East those 
which most attract the traveller's attention are the great fruit- 
bats, or flying-foxes as they are sometimes called, from the 
rusty colour of the coarse fur and .the fox-like shape of the 
head. These creatures may sometimes be seen in immense 
flocks which take hours to pass by, and they often devastate 
the fruit plantations of the natives. They are often five feet 



308 TROPICAL NATURE 



across tile expanded wings, with the body of a proportionate 
size ; and when resting in the daytime on dead trees, hanging 
head downwards, the branches look as if covered with some 
monster fruits. The descendants of the Portuguese in the East 
tise them for food, but all the native inhabitants reject them. 

In South America there is a group of bats which are sure 
to attract attention. These are the so-called vampires or 
blood-suckers, which abound in most parts of tropical Amer- 
ica, and are especially plentiful in the Amazon valley. Their 
carnivorous propensities were once discredited, but are too 
well authenticated. Horses and cattle are often bitten, and 
are found in the morning covered with blood, and repeated 
attacks weaken and ultimately destroy them. Some persons 
are especially subject to the attacks of these bats; and as 
native huts are never sufficiently close to keep them out, 
these unfortunate individuals are obliged to sleep completely 
muffled up in order to avoid being made seriously ill or even 
losing their lives. The exact manner in which the attack is 
made is not positively known, as the sufferer never feels the 
wound. The present writer was once bitten on the toe, 
which was found bleeding in the morning from a small round 
hole from which the flow of blood was not easily stopped. 
On another occasion, when his feet were carefully covered 
up, he was bitten on the tip of the nose, only awaking to find 
his face streaming with blood. The motion of the wings fans 
the sleeper into a deeper slumber, and renders him insensible 
to the gentle abrasion of the skin either by teeth or tongue. 
This ultimately forms a minute hole, the blood flowing from 
which is sucked or lapped up by the hovering vampire. The 
largest South American bats, having wings from two to two and 
a half feet in expanse, are fruiteaters like the Pteropi of the 
East, the true blood-suckers being small or of mediimi size, 
and varying in colour in different localities. They belong to 
the genus Desmodus, and have a tongue with horny papillee 
at the end ; and it is probably by means of this that they 
abrade the skin and produce a small round wound. This is 
the account given by Buffon and Azara, and there seems now 
little doubt that it is correct. 

Beyond these two great types — the monkeys and the bats 
— we look in vain among the varied forms of mammalian life 



in ANIMAL LIFE IN THE TROPICAL FORESTS 309 

for any that can be said to be distinctive of the tropics as 
compared with the temperate regions. Many peculiar groups 
are tropical, but they are in almost every case confined to 
limited portions of the tropical zones, or are rare in species or 
individuals. Such are the lemurs in Africa, Madagascar, and 
Southern Asia ; the tapirs of America and Malaya ; the rhino- 
ceroses and elephants of Africa and Asia ; the cavies and the 
sloths of America ; the scaly ant-eaters of Africa and Asia ; 
but none of these are sufficiently numerous to come often 
before the traveller so as to affect his general ideas of the 
aspects of tropical life, and they are, therefore, out of place 
in such a sketch of those aspects as we are here attempting 
to lay before om? readers. 

Summary of the Aspects of Animal Life im, the Tropics 
We wiU now briefly summarise the general aspects of 
animal life as forming an ingredient in the scenery and natural 
phenomena of the equatorial regions. Most prominent are 
the butterflies, owing to their numbers, their size, and their 
briUiant colours, as well as their peculiarities of form, and 
the slow and majestic flight of many of them. In other 
insects, the large size and frequency of protective colours 
and markings are prominent features, together with the 
inexhaustible profusion of the ants and other small insects. 
Among birds the parrots stand forth as the pre-eminent 
tropical group, as do the apes and monkeys among mammals, 
the two groups having striking analogies in the prehensile 
hand and the power of imitation. Of reptiles, the two most 
prominent groups are the lizards and the frogs ; the snakes, 
though equally abundant, being much less obtrusive. 

Animal life is, on the whole, far more abundant and more 
varied within the tropics than in any other part of the globe, 
and a great number of peculiar groups are found there which 
never extend into temperate regions. Endless eccentricities 
of form and extreme richness of coloiw are its most prominent 
features, and these are manifested in the highest degree in 
those equatorial lands where the vegetation acquires its 
greatest beauty and its fullest development. The causes of 
these essentially tropical features are not to be found in the 
comparatively simple influence of solar light and heat, but 



310 TROPICAL NATURE in 

rather in the uniformity and permanence with which these 
and all other terrestrial conditions have acted, neither varying 
prejudicially throughout the year, nor having undergone any 
important change for countless past ages. While successive 
glacial periods have devastated the temperate zones, and 
destroyed most of the larger and more specialised forms which 
during more favourable epochs had been developed, the equa- 
torial lands must always have remained thronged with life, 
and have been unintermittingly subject to those complex 
influences of organism upon organism which seem the main 
agents in developing the greatest variety of forms and filling 
up every vacant place in nature. A constant struggle against 
the vicissitudes and recurring severities of climate must always 
have restricted the range of eiFective animal variation in the 
temperate and frigid zones, and have checked all such develop- 
ments of form and colour as were in the least degree injurious 
in themselves, or which co-existed with any constitutional 
incapacity to resist great changes of temperature or other 
unfavourable conditions. Such disadvantages were not ex- 
perienced in the equatorial zone. The struggle for existence 
as against the forces of nature was there always less severe ; 
food was there more abundant and more regularly supplied ; 
shelter and concealment were at all times more easily ob- 
tained; and almost the only physical changes experienced, 
being dependent on cosmical or geological revolutions, were so 
slow that variation and natural selection were always able to 
keep the teeming mass of organisms in nicely balanced har- 
mony with the changing physical conditions. The equatorial 
zone, in short, exhibits to us the result of a comparatively 
continuous and unchecked development of organic forms ; 
while in the temperate regions there have been a series of 
periodical checks and extinctions of a more or less disastrous 
nature, necessitating the commencement of the work of de- 
velopment in certain lines over and over again. In the one, 
evolution has had a fair chance; in the other, it has had 
countless difficulties thrown in its way. The equatorial regions 
are then, as regards their past and present life-history, a more 
ancient world than that represented by the temperate zones, 
a world in which the laws which have governed the progress- 
ive development of life have operated with comparatively 



Ill ANIMAL LIFE IN THE TROPICAL FORESTS 311 

little check for countless ages, and have resulted in those 
infinitely varied and beautiful forms— those wonderful eccen- 
tricities of structure, of function, and of instinct — that rich 
variety of colour, and that nicely balanced harmony of rela- 
tions, which delight and astonish us in the animal productions 
of all tropical countries. 



rv 

HUMMING-BIEDS 

AS ILLUSTRATING THE LUXUKIANCE OF TROPICAL NATURE 

Structure — Colours and Ornaments — Descriptive Names — The Motions 
and Habits of Humming-birds — Display of Ornaments by the Male- 
Food — Nests — Geographical Distribution and Variation — Humming- 
birds of Juan Fernandez as illustrating Variation and Natural Selec- 
tion — The Relations and Affinities of Humming-birds — How to Deter- 
mine doubtful Affinities — Resemblances of Swifts and Humming-birds 
— Differences between Sun-birds and Humming-birds — Conclusion. 

There are now about ten thousand different kinds of birds 
known to naturalists, and these are classed in one hundred 
and thirty families, which vary greatly in extent, some con- 
taining a single species only, while others comprise many 
hundreds. The two largest families are those of the warblers, 
with more than six hundred, and the finches with more than 
five hundred species, spread over the whole globe ; the hawks 
and the pigeons, also spread over the whole globe, number 
about three himdred and thirty and three hundred and sixty 
species respectively; while the diminutive humming-birds, 
confined to one hemisphere, consist of about four hundred 
different species. They are thus, as regards the number of 
distinct kinds collected in a limited area, the most remarkable 
of all the families of birds. It may, however, very reasonably 
be asked, whether the four hundred species of humming-birds 
above alluded to are really all distinct — as distinct on the 
average as the ten thousand species of birds are from each 
other. We reply that they certainly are perfectly distinct 
species, which never intermingle ; and their differences do not 
consist in colour only, but in peculiarities of form, of structure, 



HUMMING-BIRDS 313 



and of habits ; so that they have to be classed in more than a 
hundred distinct genera or systematic groups of species, these 
genera being really as unlike each other as stonechats and 
nightingales, or as partridges and blackcocks. The figures we 
have quoted, as showing the proportion of birds in general to 
humming-birds, thus represent real facts ; and they teach us 
that these small and in some respects insignificant birds con- 
stitute an important item in the animal life of the globe. 

Humming-birds are, in many respects, unusually interesting 
and instructive. They are highly peculiar in form, in struc- 
ture, and in habits, and are quite unrivalled as regards variety 
and beauty. Though the name is familiar to every one, few 
but naturalists are acquainted with the many curious facts in 
their history, or know how much material they afibrd for 
admiration and study. It is proposed, therefore, to give a 
brief and popular account of the form, structure, habits, dis- 
tribution, and afiSnities of this remarkable family of birds, as 
illustrative of the teeming luxuriance of tropical nature, and 
as throwing light on some of the most interesting problems of 
natural history. 

Strudwre 

The humming-birds form one compact family named 
Trochilidse. They are aU small birds, the largest known being 
about the size of a swallow, while the smallest are minute 
creatures, whose bodies are hardly larger than a humble-bee. 
Their distinguishing features are excessively short legs and 
feet, very long and pointed wings, a long and slender bill, 
and a long extensible tubular tongue ; and these characters are 
found combined in no other birds. The feet are exceedingly 
small and delicate, often beautifully tufted with down, and so 
short as to be hardly visible beyond the plumage. The toes 
are placed as in most birds, three in front and one behind, 
and have very strong and sharply curved claws ; and the feet 
serve probably to cling to a perch rather than to give any 
movement to the body. The wings are long and narrow, but 
strongly formed ; and the first qmll is the longest, a peculiarity 
found in hardly any other birds but a few of the swifts. The 
bill varies greatly in length, but is always long, slender, and 
pointed, the upper mandible being the widest and lapping 



314 TROPICAL NATURE 



over the lower at each side, thus affording complete protection 
to the delicate tongue, the perfect action of which is essential 
to the bird's existence. The humming-bird's tongue is very- 
long, and is capable of being greatly extended beyond the 
beak and rapidly drawn back, by means of muscles which are 
attached to the hyoid or tongue-bones, and bend round over 
the back and top of the head to the very forehead, just as in 
the woodpeckers. The two blades or laminae of which the 
tongues of birds usually seem to be formed are here greatly 
lengthened, broadened out, and each rolled up ; so as to form 
a complete double tube connected down the middle, and ivith 
the outer edges in contact but not united. The extremities 
of the tubes are, however, flat and fibrous. This tubular and 
retractile tongue enables the bird to suck up honey from the 
nectaries of flowers, and also to capture small insects ; but 
whether the latter pass down the tubes, or are entangled in 
the fibrous tips and thus draw back into the gullet, is not 
known. The only other birds with a similar tubidar tongue are 
the sun-birds of the East, which, however, as we shall presently 
explain, have no affinity whatever with the humming-birds. 

Colowrs and Ornaments 

The colours of these small birds are exceedingly varied and 
exquisitely beautiful. The basis of the colouring may be said 
to be green, as in parrots ; but whereas in the latter it is a 
silky green, in humming-birds it is always metallic. The 
majority of the species have some green about them, especially 
on the back ; but in a considerable number rich blues, purples, 
and various shades of red are the prevailing tints. The 
greater part of the plumage has more or less of a metallic 
gloss, but there is almost always some part which has an 
intenser lustre, as if actually formed of scales of burnished 
metal. A gorget, covering the greater part of the neck and 
breast, most commonly displays this vivid colour ; but it also 
frequently occurs on the head, on the back, on the taU-coverts 
above or below, on the upper surface of the tail, on the 
shoulders or even the quiUs. The hue of every precious 
stone and the lustre of every metal is here represented ; 
and such terms as topaz, amethyst, beryl, emerald, garnet, 
ruby, sapphire ; golden, golden-green, coppery, fiery, glowing. 



HUMMING-BIRDS 315 



iridescent, refulgent, celestial, glittering, shining, are con- 
stantly used to name or describe the different species. 

No less remarkable than the colours are the varied develop- 
ments of plumage with which these birds are adorned. The 
head is often crested in a variety of ways ; either a simple 
flat crest, or with radiating feathers, or diverging into two 
horns, or spreading laterally Uke wings, or erect and bushy, 
or recurved and pointed like that of a plover. The throat 
and breast are usually adorned with broad scale-like feathers, 
or these diverge into a tippet, or send out pointed collars, or 
elegant frills of long and narrow plumes tipped with metallic 
spots of various colours. But the tail is even a more varied 
and beautiful ornament, either short and rounded, but pure 
white or some other strongly contrasted tint ; or with short 
pointed feathers forming a star; or with the three outer 
feathers on each side long and tapering to a point ; or larger, 
and either square or round, or deeply forked or acutely 
pointed; or with the two middle feathers excessively long 
and narrow ; or with the tail very long and deeply forked, 
with broad and richly-coloured feathers; or with the two 
outer feathers wire-Hke and having broad spoon-shaped tips. 
AH these ornaments, whether of the head, neck, breast, or 
tail, are invariably coloured in some effective or brilliant 
manner, and often contrast strikingly with the rest of the 
plumage. Again, these colours often vary in tint according 
to the direction in which they are seen. In some species they 
must be looked at from above, in others from below ; in some 
from the front, in others from behind, in order to catch the full 
glow of the metallic lustre ; hence, when the birds are seen in 
their native haunts, the colours come and go and change with 
their motions, so as to produce a startling and beautiful effect. 

The bin differs greatly in length and shape, being either 
straight or gently curved, in some species bent Hke a sickle, 
in others turned up Uke the bUl of the avoset. It is usually 
long and slender, but in one group is so enormously developed 
that it is nearly the same length as the rest of the bird. The 
legs, usually little seen, are in some groups adorned with 
globular tufts of white, brown, or black down, a peculiarity 
possessed by no other birds. The reader wiU now be in a 
position to understand how the four hundred species of 



316 TROPICAL NATURE iv 

humming-birds may be easily distinguished, by the varied 
combinations of the characters here briefly enumerated, to- 
gether with many others of less importance. One group of 
birds will have a short round tail, with crest and long neck- 
frill; another group a deeply-forked broad tail, combined 
with glowing crown and gorget; one is both bearded and 
crested; others have a luminous back and pendent neck- 
plumes ; and in each of these groups the species will vary in 
combinations of colour, in size, and in the proportions of the 
ornamental plumes, so as to produce an unmistakable dis- 
tinctness; while, without any new developments of form or 
structure, there is room for the discovery of hundreds more of 
distinct kinds of humming-birds. 

Descriptive Names 

The name we usually give to the birds of this family is derived 
from the sound of their rapidly-moving wings, a sound which 
is produced by the largest as weU as by the smallest member of 
the group. The Creoles of Guiana similarly call them Bourdons 
or hummers. The French term, Oiseau-mouche, refers to their 
small size ; while Colibri is a native name which has come 
down from the Carib inhabitants of the West Indies. The 
Spaniards and Portuguese call them by more poetical names, 
such as flower-peckers, flower-kissers, myrtle-suckers — while 
the Mexican and Peruvian names show a still higher apprecia- 
tion of their beauties, their meaning being " rays of the sun," 
" tresses of the day-star," and other such appellations. Even 
our modern naturalists, while studying the structure and 
noting the peculiarities of these living gems, have been 
so struck by their inimitable beauties that they have en- 
deavoured to invent appropriate English names for the more 
beautiful and remarkable genera. Hence we find in common 
use such terms as sun-gems, sun-stars, hill-stars, wood-stars, 
sun-angels, star-throats, comets, coquettes, flame-bearers, 
sylphs, and fairies ; together with many others derived from 
the character of the tail or the crests. 

The Motions and Habits of Evmming-Birds 

Let us now consider briefly the peculiarities of flight, the 
motions, the food, the nests, and general habits of the humming- 



HUMMINO-BIRDS 317 



birds, quoting the descriptions of those modern naturalists 
who have personally observed them. Their appearance, 
remarks Professor Alfred Newton, is entirely unlike that of 
any other bird : " One is admiring some brilliant and beauti- 
ful flower, when between the blossom and one's eye suddenly 
appears a small dark object, suspended as it were between four 
short black threads meeting each other in a cross. For an 
instant it shows in front of the flower ; again another instant, 
and emitting a momentary flash of emerald and sapphire light, 
it is vanishing, lessening in the distance, as it shoots away, to 
a speck that the eye cannot take note of." Audubon observes 
that the Euby humming-birds pass through the air in long 
undulations, but the smallness of their size precludes the pos- 
sibility of following them with the eye farther than fifty or 
sixty yards, without great difficulty. A person standing in a 
garden by the side of a common althsea in bloom, will hear 
the humming of their wings and see the little birds themselves 
within a few feet of him one moment, while the next they 
will be out of sight and hearing. Mr. Gould, who visited 
North America in order to see living humming-birds while 
preparing his great work on the family, remarks that the 
action of the wings reminded him of a piece of machinery 
acted upon by a powerful spring. When poised before a 
flower, the motion is so rapid that a hazy semicircle of indis- 
tinctness on each side of the bird is all that is perceptible. 
Although many short intermissions of rest are taken, the bird 
may be said to live in the air — an element in which it per- 
forms every kind of evolution with the utmost ease, frequently 
rising perpendicularly, flying backward, pirouetting or dancing 
ofij as it were, from place to place, or from one part of a tree 
to another, sometimes descending, at others ascending. It 
often mounts up above the towering trees, and then shoots off 
like a little meteor at a right angle. At other times it gently 
buzzes away among the little flowers near the ground ; at one 
moment it is poised over a diminutive weed, at the next it is 
seen at a distance of forty yards, whither it has vanished with 
the quickness of thought. 

The Eufous Flame - bearer, an exquisite species found 
on the west coast of North America, is thus described by 
Mr. Nuttall : " When engaged in collecting its accustomed 



318 TROPICAL NATURE iv 

sweets, in all the energy of life, it seemed like a breathing 
gem, a magic carbuncle of flaming fire, stretching out its 
glorious ruflf as if to emulate the sun itself in splendour." 
The Sappho Comet, whose long forked tail barred with 
crimson and black renders it one of the most imposing of 
humming-birds, is abundant in many parts of the Andes; 
and Mr. Bonelli tells us that the difficulty of shooting them 
is very great from the extraordinary turns and evolutions 
they make when on the wing ; at one instant darting head- 
long into a flower, at the next describing a circle in the air 
with such rapidity that the eye, unable to follow the move- 
ment, loses sight of the bird until it again returns to the 
flower which at first attracted its attention. Of the little 
Vervain humming-bird of Jamaica, Mr. Gosse writes : " I 
have sometimes watched with much delight the evolutions of 
this little species at the Moringa-tree.^ When only one is 
present, he pursues the round of the blossoms soberly enough. 
But if two are at the tree, one will fly off, and suspend 
himself in the air a few yards distant ; the other presently 
starts off to him, and then, without touching each other, they 
mount upwards with strong rushing wings, perhaps for five 
hundred feet. They then separate, and each starts diagonally 
towards the ground like a ball from a lifle, and, wheeling 
roimd, comes up to the blossoms again as if it had not moved 
away at all. The figure of the smaller humming-birds on the 
wing, their rapidity, their wavering course, and their whole 
manner of flight, are entirely those of an insect." Mr. Bates 
remarks that on the Amazons, during the cooler hours of the 
morning and from four to six in the afternoon, humming- 
birds are to be seen whirring about the trees by scores ; their 
motions being unlike those of any other birds. They dart to 
and fro so swiftly that the eye can scarcely follow them, and 
when they stop before a flower it is only for a few moments. 
They poise themselves in an unsteady manner, their wings 
moving with inconceivable rapidity, probe the flower, and 
then shoot off to another part of the tree. They do not 
proceed in that methodical manner which bees follow, taking 

' Sometimes called tlie horse-radish tree. It is the Moringa pterygosperma, 
a native of the East Indies, but commonly cultivated in Jamaica. It has 
yellow flowers. 



IV HUMMING-BIRDS 319 

the flowers seriatim, but skip about from one part of the tree 
to another in the most capricious way. Mr. Belt remarks on 
the excessive rapidity of the flight of the humming-bird giving 
it a sense of security from danger, so that it will approach a 
person nearer than any other bird, often hovering within two 
or three yards (or even one or two feet) of one's face. He 
watched them bathing in a small pool in the forest, hovering 
over the water, turning from side to side by quick jerks of 
the tail; now showing a throat of gleaming emerald, now 
shoulders of glistening amethyst; then darting beneath the 
water, and rising instantly, throw off a shower of spray from 
its quivering wings, and again fly up to an overhanging 
bough and commence to preen its feathers. AH humming- 
birds bathe on the vring, and generally take three or four 
dips, hovering between times about three or four inches 
above the surface. Mr. Belt also remarks on the immense 
numbers of humming-birds in the forests, and the great 
difficulty of seeing them ; and his conclusion is, that in the 
part of Nicaragua where he was living they equalled in 
number all the rest of the birds together, if they did not 
greatly exceed them. 

The extreme pugnacity of humming-birds has been noticed 
by all observers. Mr. Gosse describes two meeting and 
chasing each other through the labyrinths of twigs and 
flowers till, an opportunity occurring, the one would dart 
with seeming fury upon the other, and then, with a loud 
rustling of their wings, they would tvrirl together, round and 
round, till they nearly came to the earth. Then they parted, 
and after a time another tussle took place. Two of the same 
species can hardly meet without an encounter, while in many 
cases distinct species attack each other with equal fury. Mr. 
Salvin describes the splendid Eugenes fulgens attacking two 
other species with as much ferocity as its own fellows. 
One will knock another off its perch, and the two will 
go fighting and screaming away at a pace hardly to be 
followed by the eye. Audubon says they attack any other 
birds that approach them, and think nothing of assaulting 
tyrant -shrikes and even birds of prey that come too near 
their home. 



320 TROPICAL NATURE 



Display of Ornaments by the Male 

It is a ■well-known fact that -when male birds possess any- 
unusual ornaments, they take such positions or perform such 
evolutions as to exhibit them to the best advantage while 
endeavouring to attract or charm the females, or in rivalry 
with other males. It is therefore probable that the wonder- 
fully varied decorations of humming-birds, whether burnished 
breast - shields, resplendent tail, crested head, or glittering 
back, are thus exhibited ; but almost the only actual observa- 
tion of this kind is that of Mr. Belt, who describes how two 
males of the Florisuga mellivora displayed their ornaments 
before a female bird. One would shoot up like a rocket, 
then, suddenly expanding the snow-white tail like an inverted 
parachute, slowly descend in front of her, turning round 
gradually to show off both back and front. The expanded 
white tail covered more space than all the rest of the bird, 
and was evidently the grand feature of the performance. 
Whilst one was descending the other would shoot up and 
come slowly down expanded. ^ 

Food 

The food of humming-birds has been a matter of much 
controversy. All the early writers, down to Buffon, believed 
that they lived solely on the nectar of flowers ; but since that 
time every close observer of their habits maintains that they 
feed largely, and in some cases wholly, on insects. Azara 
observed them on the La Plata in winter, taking insects out 
of the webs of spiders at a time and place where there were 
no flowers. Bullock, in Mexico, declares that he saw them 
catch small butterflies, and that he found many kinds of 
insects- in their stomachs. Waterton made a similar state- 
me^nt. Hundreds and perhaps thousands of specimens have 
since been dissected by collecting naturalists, and in almost 
every instance their stomachs have been found full of insects 
— sometimes, but not generally, mixed with a proportion of 
honey. Many of them in fact may be seen catching gnats 
and other small insects just like fly-catchers, sitting on a dead 
twig over water, darting off" for a time in the air, and then 
' The NatwraUat in Nica/ragua, p. 112, 



HUMMING-BIRDS 321 



returning to the twig. Others come out just at dusk, and 
remain on the wing, now stationary, now darting about with 
the greatest rapidity, imitating in a limited space the evolu- 
tions of the goatsuckers, and evidently for the same end 
and purpose. Mr. Gosse also rmnarks : " All the humming- 
birds have more or less the habit, when in flight, of pausing 
in the air and throwing the body and tail into rapid and odd 
contortions. This is most observable in the Polytmus, from 
the effect that such motions have on the long feathers of the 
tail. That the object of these quick turns is the capture of 
insects, I am sure, having watched one thus engaged pretty 
close to me. I observed it carefully, and distinctly saw the 
minute flies in the air which it pursued and caught, and 
heard repeatedly the snapping of the beak. My presence 
scarcely disturbed it, if at all." 

There is also an extensive group of small brown humming- 
birds, forming the sub-family Phaethornithinse, which rarely 
or never visit flowers, but frequent the shady recesses of the 
forest, where they hunt for minute insects. They dart about 
among the foliage, and visit in rapid succession every leaf 
upon a branch, balancing themselves vertically in the air, 
passing their beaks closely over the under-surface of each leaf, 
and thus capturing, no doubt, any small insects that may 
lurk there. While doing this, the two long feathers of the 
tail have a vibrating motion, serving apparently as a rudder 
to assist them in performing the delicate operation. Others 
search up and down stems and dead sticks in the same 
manner, every now and then picking off something, exactly 
as a bush -shrike or a tree-creeper does, with the difference 
that the humming-bird is constantly on the wing ; whUe the 
remarkable sickle-bill is said to probe the scale-covered stems 
of palms and tree-ferns to obtain its insect food. 

It is a well-known fact that although humming-birds are 
easily tamed, they cannot be preserved long in captivity, even 
in their own country, when fed only on syrup. Audubon 
states that when thus fed they only live a month or two and 
die apparently starved ; while if kept in a room whose open 
windows are covered with a fine net, so as to allow small 
insects to enter, they have been kept for a whole year without 
any iU effects. Another writer, Mr. Webber, captured and 

V 



322 TROPICAL NATURE 



tamed a number of the Euby-throat in the United States. He 
found that when fed for three weeks on syrup they drooped, 
but after being let free for a day or two they would return to 
the open cage for more of the syrup. Some which had been 
thus tamed and set free returned the following year, and at 
once flew straight to the remembered little cup of sweets. 
Mr. Grosse in Jamaica also kept some in captivity, and found 
the necessity of giving them insect food ; and he remarks 
that they were very fond of a small ant that swarmed on the 
syrup with which they were fed. It is strange that, with all 
this previous experience and information, those who have 
attempted to bring live humming-birds to this country have 
fed them exclusively on syrup ; and the weakness produced 
by this insufficient food has no doubt been the chief cause of 
their death on, or very soon after, arrival. A box of ants 
would not be difficult to bring as food for them, but even 
finely-chopped meat or yolk of egg would probably serve, in 
the absence of insects, to supply the necessary proportion of 
animal food. 

Nests 

The nests of the humming-birds are, as might be expected, 
beautiful objects, some being no larger inside than the half of 
a walnut shell. These small cup-shaped nests are often placed 
in the fork of a branch, and the outside is sometimes beauti- 
fully decorated with pieces of lichen, the body of the nest 
being formed of cottony substances and the inside lined with 
the finest and most silky fibres. Others suspend their nests 
to creepers hanging over water, or even over the seaj and 
the Pichincha humming-bird once attached its nest to a straw- 
rope hanging from the roof of a shed. Others again build 
nests of a hammock-form attached to the face of rocks by 
spiders' web; while the little forest-haunting species fasten 
their nests to the points or to the under-sides of palm-leaves 
or other suitable foliage. They lay only one or two white 



Geographical Distribution and Variation 

Most persons know that humming-birds are found only in 
America ; but it is not so generally known that they are 
almost exclusively tropical birds, and that the few species that 



HUMMING-BIRDS 323 



are found in the temperate (northern and southern) parts of 
the continent are migrants, which retire in the winter to the 
warmer lands near or within the tropics. In the extreme 
north of America two species are regular summer Yisitants, one 
on the east and the other on the west of the Eocky Mountains. 
On the east the common North American or Euby-throated 
humming-bird extends through the United States and Canada, 
and as far as 57° north latitude, or considerably north of 
Lake Winnipeg ; while the milder climate of the west coast 
allows the Rufous Flame-bearer to extend its range beyond 
Sitka to the parallel of 61°. Here they spend the whole 
summer, and breed, being found on the Columbia River in the 
latter end of April, retiring to Mexico in the winter. Sup- 
posing that those which go farthest north do not return 
farther south than the borders of the tropics, these little 
birds must make a journey of full three thousand miles each 
spring and autumn. The antarctic humming-bird visits the 
inhospitable shores of Tierra-del-Fuego, where it has been 
seen visiting the flowers of fuchsias in a snowstorm, while 
it spends the winter in the warmer parts of ChUi and 
Bolivia. 

In the south of CaUfornia and in the Central United 
States three or four other species are found in summer ; but 
it is only when we enter the tropics that the number of 
dififerent kinds becomes considerable. In Mexico there are 
more than thirty species, while in the southern parts of 
Central America there are more than double that number. 
As we go on towards the equator they become stiU more 
numerous, till they reach their maximum in the equatorial 
Andes. They especially abound in the mountainous regions ; 
while the luxuriant forest plains of the Amazons, in which so 
many other forms of life reach their maximum, are very poor 
in humming-birds. Brazil, being more hilly and with more 
variety of vegetation, is richer, but does not equal the Andean 
valleys, plateaux, and volcanic peaks. Each separate district 
of the Andes has its peculiar species and often its peculiar 
genera, and many of the great volcanic mountains possess 
kinds which are confined to them. Thus, on the great 
mountain of Pichincha there is a peculiar species found at an 
elevation of about fourteen thousand feet only; while an 



324 TROPICAL NATURE 



allied species on Cliiinborazo ranges from fourteen thousand 
feet to the limits of perpetual snow at sixteen thousand feet 
elevation. It frequents a beautiful yellow -flowered alpine 
shrub belonging to the Asteracese. On the extinct volcano of 
Chiriqui in Veragua a minute humming-bird, called the little 
Flame -bearer, has been only found inside the crater. Its 
scaled gorget is of such a flaming crimson that, as Mr. Gould 
remarks, it seems to have caught the last spark from the 
volcano before it was extinguished. 

Not only are humming-birds found over the whole extent 
of America, from Sitka to Tierra-del-Fuego, and from the 
level of the sea to the snow-line on the Andes, but they in- 
habit many of the islands at a great distance from the main- 
land. The West Indian islands possess fifteen distinct species 
belonging to eight difi'erent genera, and these are so unlike 
any found on the continent that five of these genera are 
peculiar to the Antilles. Even the Bahamas, so close to 
Florida, possess two peculiar species. The small group of 
islands called Tres Marias, about sixty miles from the west 
coast of Mexico, has a peculiar species. More remarkable are 
the two humming-birds of Juan Fernandez, situated in the 
Pacific Ocean, four hundred miles west of Valparaiso in ChiH, 
one of these being peculiar ; while another species inhabits 
the little island Mas-afuera, ninety miles farther west. The 
Galapagos, though very little farther from the mainland and 
much more extensive, have no humming-birds ; neither have 
the Falkland islands, and the reason seems to be that both 
these groups are deficient in forest, and in fact have hardly 
any trees or large shrubs, while there is a great paucity of 
flowers and of insect life. 

Evmming-Urds of Juan Fernandez as illustrating Variation and 
Natural Selection 

The three species which inhabit Juan Fernandez and Mas- 
afuera present certain peculiarities of great interest. They 
form a distinct genus, Eustephanus, one species of which in- 
habits Chili as well as the island of Juan Fernandez. This, 
which may be termed the Chilian species, is greenish in both 
sexes, whereas in the two species peculiar to the islands the 
males are red or reddish-brown, and the females green. The 



HUMMING-BIRDS 325 



two red males differ very slightly from each other, but the 
three green females differ considerably ; and the curious point 
is that the female in the smaller and more distant island some- 
what resembles the same sex in ChUi, while the female of t^he 
Juan Fernandez species is very distinct, although the males 
of the two islands are so much alike. As this forms a com- 
paratively simple case of the action of the laws of variation 
and natural selection, it wiU be instructive to see if we can 
picture to ourselves the process by which the changes have 
been brought about. We must first go back to an unknown 
but rather remote period, just before any humming-birds had 
reached these islands. At that time a species of this peculiar 
genus, Eustephanus, must have inhabited Chili ; but we can- 
not be sure that it was identically the same as that which is 
now found there, because we know that species are always 
undergoing change to a greater or less degree. After perhaps 
many failures, one or more pairs of the Chilian bird got blown 
across to Juan Fernandez, and finding the country favourable, 
with plenty of forests and a fair abundance of flowers and 
insects, they rapidly increased and permanently established 
themselves on the island. They soon began to change colour, 
however, the male getting a tinge of reddish-brown, which 
gradually deepened into the fine colour now exhibited by the 
two insular species, while the female, more slowly, changed 
to white on the under - surf ace and on the tail, while the 
breast -spots became more briUiant. When the change of 
colour was completed in the male, but only partially so in the 
female, a further emigration westward took place to the 
small island Mas-afuera, where they also established them- 
selves. Here, however, the change begun in the larger island 
appears to have been checked, for the female remains to this 
day intermediate between the Juan Fernandez and the Chilian 
forms. More recently, the parent form has again migrated 
from Chili to Juan Fernandez, where it still Hves side by side 
with its greatly changed descendant.^ Let us now see how 
far these facts are in accordance with the general laws of 

^ In tie preceding account of the probable course of events in peopling 
these islands with humming-birds, I follow Mr. Sclater's paper on the 
"Land Birds of Juan Fernandez," Ibis, 1871, p. 183. In what follows I 
give my own explanation of the probable causes of the change. 



326 TROPICAL NATURE 



variation, and with those other laws which I have endeavoured 
to show regulate the development of colour.^ 

The amount of variation which is likely to occur in a 
species will be greatly influenced by two factors — the occur- 
rence of a change in the physical conditions, and the average 
abundance or scarcity of the individuals composing the species. 
When from these or other causes variation occurs, it may 
become fixed as a variety or a race, or may go on increasing 
to a certain extent, either from a tendency to vary along 
certain special lines induced by local or physiological causes, 
or by the continued survival and propagation of all such 
varieties as are beneficial to the race. After a certain time 
a balance will be arrived at, either by the limits of useful 
variation in this one direction having been reached, or by the 
species becoming harmoniously adapted to all the surrounding 
conditions : and without some change in these conditions the 
specific form may then remain unaltered for a very long time ; 
whence arises the common impression of the fixity of species. 
Now in a country like Chili, forming part of a great continent 
very well stocked with all forms of organic life, the majority 
of the species would be in a state of stable equilibrium ; the 
most favourable variations would have been long ago selected ; 
and the numbers of individuals in each species would be 
tolerably constant, being limited by the numerous other forms 
whose food and habits were similar, or which in any way 
impinged upon its sphere of existence. We may, therefore, 
assume that the Chilian humming-bird which migrated to 
Juan Fernandez was a stable form, hardly if at all different 
from the existing species which is termed Eustephanus 
galeritus. On the island it met with very changed but 
highly favourable conditions — an abundant shrubby vegeta- 
tion and a tolerably rich flora ; less extremes of climate than 
on the mainland ; and, most important of all, absolute freedom 
from the competition of rival species. The flowers and their 
insect inhabitants were all its own ; there were no snakes or 
mammalia to plunder its nests ; nothing to prevent the full 
enjoyment of existence. The consequence would be, rapid 
increase and a large permanent population, which still main- 

^ See Macmillan's Magazine, September 1867, " On the Colours of Animals 
and Plants," and chapters v. and vi., post. 



rv HUMMING-BIRDS 327 

tains itself ; for Mr. Moseley, of the Challenger expedition, has 
informed the writer that humming-birds are extraordinarily 
abundant in Juan Fernandez, every bush or tree having one 
or two darting about it. Here, then, we have one of the 
special conditions which have always been held to favour 
variation — a great increase in the number of individuals ; but, 
as there was no struggle with allied creatures, there was no 
need for any modification in form or structure, and we accord- 
ingly find that the only important variations which have 
become permanent are those of size and of colour. The 
increased size would naturally arise from greater abundance 
of food with a more equable climate throughout the year; 
the healthier, stronger, and larger individuals being preserved. 
The change of colour would depend on molecular changes in 
the plumage accompanying the increase of size ; and the 
superior energy and vitality in the male, aided by the favour- 
able change in conditions and rapid increase of population, 
would lead to an increased intensity of colour, the special tint 
being determined either by local conditions or by inherited 
tendencies in the race. It is to be noted that the change 
from green to red is in the direction of the less refrangible 
rays of the spectrum, and is in accordance with the law of 
change which has been shown to accompany expansion in 
inorganic growth and development in organic forms.^ The 
change of colour in the female, not being urged on by such 
intense vital activity as in the case of the male, would be 
much slower, and, owing probably to inherited tendencies, in 
a different direction. The under-surface of the Chilian bird 
is ashy with bronzy-green spots on the breast, while the tail 
is entirely bronze-green. In the Juan Fernandez species the 
under-surface has become pure white, the breast-spots larger 
and of a purer golden-green, while the whole inner web of the 
tail-feathers has become pure white, producing a most elegant 
effect when the tail is expanded. 

We may now follow the two sexes to the remoter island, 
at a period when the male had acquired his permanent style 
of colouring, but was not quite so large as he subsequently 
became ; while the change of the female bird had not been 

' See "Colours of Animals," Macmillan's Magazine, September 1877, pp 
394-398, and chapter v., post. 



328 TROPICAL NATURE 



half completed. In this small and comparatively barren 
island (a mere rock, as it is described by some authors) there 
would be no such constant abundance of food, and therefore 
no possibility of a large permanent population of humming- 
birds; while the climate would not differ materially from 
that of the larger island. Variation would therefore be 
checked, or might be stopped altogether; and we find the 
facts exactly correspond to this view. The male, which had 
abeady acquired his colour, remains almost undistinguishable 
from his immediate ancestral form ; but he is a little smaller, 
indicating either that the full size of that form had not been 
acquired at the period of migration, or that a slight diminution 
of size has since occurred, owing to a deficiency of food. The 
female shows also a slight diminution of size, but in other 
respects is almost exactly intermediate between the Chilian and 
Juan Fernandez females. The colour beneath is light ashy, the 
breast-spots are intermediate in size and colour, and the tail- 
feathers have a large ill-defined white spot on the end of the 
inner web which has only to be extended along the whole web 
to produce the exact character which has been acquired in 
Juan Fernandez. It seems probable, therefore, that the 
female bird has remained nearly or quite stationary since its 
migration, while its Juan Fernandez relative has gone on 
steadily changing in the direction already begun; and the 
more distant species geographically thus appears to be more 
nearly related to its Chilian ancestor. 

Coming down to a more recent period, we find that the 
comparatively small and dull-coloured Chilian bird has again 
migrated to Juan Fernandez ; but it at once came into 
competition with its red descendant, which had firm possession 
of the soil, and had probably undergone slight constitutional 
changes exactly fitting it to its insular abode. The new- 
comer, accordingly, only just manages to maintain its footing ; 
for we are told by Mr. Reed of Santiago that it is by no 
means common ; whereas, as we have seen, the red species is 
excessively abundant. We may further suspect that the 
Chilian birds now pass over pretty frequently to Juan 
Fernandez, and thus keep up the stock; for it must be 
remembered that whereas, at a first migration, both a male 
and a female are necessary for colonisation, yet, after a 



HUMMmG-BIRDS 329 



colony is formed, any stray bird which may come over adds 
to the numbers, and checks permanent variation by cross- 
breeding. 

We find, then, that all the chief peculiarities of the three 
allied species of humming-birds which inhabit the Juan 
Fernandez group of islands, may be fairly traced to the action 
of those general laws which Mr. Darwin and others have 
shown to determine the variation of animals and the per- 
petuation of those variations. It is also instructive to note 
that where the variations of colour and size have been greatest 
they are accompanied by several lesser variations in other 
characters. In the Juan Fernandez bird the bill has become 
a little shorter, the tail feathers somewhat broader, and the 
fiery cap on the head somewhat smaller ; all these peculiarities 
being less developed or absent in the birds inhabiting Mas- 
afuera. These coincident changes may be due, either to 
what Mr. Darwin has termed correlation of growth, or to 
the partial reappearance of ancestral characters under more 
favourable conditions, or to the direct action of changes of 
climate and of food ; but they show us how varied and un- 
accountable are the changes in specific forms that may be 
effected in a comparatively short time, and by means of very 
slight changes of locality. 

If now we consider the enormously varied conditions 
presented by the whole continent of America — the hot, moist, 
and uniform forest-plains of the Amazon ; the open llanos of 
the Orinoco ; the dry uplands of Brazil ; the sheltered valleys 
and forest slopes of the Eastern Andes ; the verdant plateaux, 
the barren paramos, the countless volcanic cones with their 
peculiar Alpine vegetation; the contrasts of the east and 
west coasts ; the isolation of the West Indian islands, and to 
a less extent of Central America and Mexico, which we know 
have been several times separated from South America ; and 
when we further consider that all these characteristically 
distinct areas have been subject to cosmical and local changes, 
to elevations and depressions, to diminution and increase of 
size, to greater extremes and greater uniformity of temper- 
ature, to increase or decrease of rainfall ; and that with these 
changes there have been coincident changes of vegetation and 
of animal life, all affecting in countless ways the growth and 



330 TROPICAL NATURE 



development, the forms and colours, of these ■wonderful little 
birds — if we consider all these varied and complex influences, 
we shall be less surprised at their strange forms, their infinite 
variety, their wondrous beauty. For how many ages the 
causes above enumerated may have acted upon them we 
cannot say ; but their extreme isolation from all other birds, 
no less than the abundance and variety of their generic and 
specific forms, clearly point to a very high antiquity. 

The delations and Affinities of Humming-birds 

The question of the position of this family in the class 
of birds and its affinities or resemblances to other groups 
is so interesting, and affords such good opportunities for 
explaining some of the best established principles of classifica- 
tion in natural history in a popular way, that we propose to 
discuss it at some length, but without entering into technical 
details. 

There is in the Eastern hemisphere, especially in tropical 
Africa and Asia, a family of small birds called sun-birds, which 
are adorned with brilliant metallic colours, and which, in shape 
and general appearance, much resemble humming-birds. They 
frequent flowers in the same way, feeding on honey and insects ; 
and all the older naturalists placed the two families side by 
side as undoubtedly allied. In the year 1850, in a general 
catalogue of birds. Prince Lucien Bonaparte, a learned 
ornithologist, placed the humming-birds next to the swifts, 
and far removed from the Nectarinidae or sun-birds ; and this 
view of their position has gained ground with increasing 
knowledge, so that now all the more advanced ornithologists 
have adopted it. Before proceeding to point out the reasons 
for this change of view, it will be well to discuss a few of the 
general principles which guide naturalists in the solution of 
such problems. 

How to Determine doubtful Affinities 

It is now generally admitted that, for the purpose of 
determining obscure and doubtful affinities, we must examine 
by preference those parts of an animal which have little or no 
direct influence on its habits and general economy. The value 
of an organ, or of any detail of structure, for purposes of 



HUMMING-BIRDS 331 



classification, is generally in inverse proportion to its adapt- 
ability to special uses. And the reason of this is apparent, 
when we consider that similarities of food and habits are often 
accompanied by similarities of external form or of special 
organs, in totally distinct animals. Porpoises, for example, 
are modified externally so as to resemble fishes ; yet they are 
really mammaUa. Some marsupials are carnivorous, and are 
so Hke true carnivora that it is only by minute peculiarities of 
structure that the skeleton of the one can be distinguished 
from that of the other. Many of the hornbUls and toucans 
have the same general form, and resemble each other in habits, 
in food, and in their enormous bills ; yet peculiarities in the 
structure of the feet, in the form of the breast-bone, in the 
cranium, and in the texture and arrangement of the plumage, 
show that they have no real affinity, the former approach- 
ing the kingfishers, the latter the cuckoos. Such structural 
peculiarities as these have no direct relation to habits ; and 
they are therefore little liable to change, when from any cause 
a portion of the group may have been driven to adopt a new 
mode of life. Thus all the Old World apes, however much 
they may dififer in size or habits, and whether we class them 
as baboons, monkeys, or anthropoids, have the same number 
of teeth ; while the American monkeys all have an additional 
premolar tooth. This difference can have no relation to the 
habits of the two groups, because each group exhibits dififer- 
ences of habits greater than often occur between American 
and Asiatic species ; and it thus becomes a valuable character 
indicating the radical distinctness of the two groups, a distinct- 
ness confirmed by other anatomical characters. 

On the other hand, peculiarities of organisation which seem 
specially adapted to certain modes of life are often diminished 
or altogether lost in a few species of the group, showing their 
essential unimportance to the type, as well as their small 
value for classification. Thus the woodpeckers are most 
strikingly characterised by a very long and highly extensible 
tongue, with the muscles attached to the tongue-bone prolonged 
backward over the head so as to enable the tongue to be 
suddenly darted out ; and also by the rigid and pointed tail, 
which is a great help in climbing up the vertical trunks of 
trees. But in one group (the Pictimni) the tail becomes quite 



332 TROPICAL NATURE IV 

soft, -while the tongue remains fully developed ; and in another 
(Meiglyptes) the characteristic tail remains, while the prolonged 
hyoid muscles have almost entirely disappeared, and the 
tongue has consequently lost its peculiar extensile power ; yet 
in both these cases the form of the breast-bone and the 
character of the feet, the skeleton, and the plumage, show that 
the birds are really woodpeckers ; while even the habits and 
the food are very little altered. In like manner the bill may 
undergo great changes ; as from the short crow-like bill of the 
true birds-of-paradise to the long slender bills of Epimachinse, 
which latter were on that account long classed apart in the 
tribe of Tenuirostres, or slender-billed birds, but whose entire 
structure shows them to be closely allied to the paradise-birds. 
So, the long feathery tongue of the toucans differs from that of 
every other bird ; yet it is not held to overbalance the weight 
of anatomical peculiarities which show that these birds are 
allied to the barbets and the cuckoos. 

The skeleton, therefore, and especially the sternum or 
breast-bone, affords us an almost infallible guide in doubtful 
cases; because it appears to change its form with extreme 
slowness, and thus indicates deeper seated affinities than those 
shown by organs which are in direct connection with the out- 
side world, and are readily modified in accordance with varying 
conditions of existence. Another, though less valuable guide 
is afforded, in the case of birds, by the eggs. These often 
have a characteristic form and colour, and a peculiar texture 
of surface, running unchanged through whole genera and 
families which are nearly related to each other, however much 
they may differ .in outward form and habits. Another detail 
of structure, which has no direct connection with habits and 
economy, is the manner in which the plumage is arranged on 
the body. The feathers of birds are by no means set uni- 
formly over their skin, but grow in certain definite lines and 
patches, which vary considerably in shape and size in the more 
important orders and tribes, while the mode of arrangement 
agrees in all which are known to be closely related to each 
other ; and thus the form of the feather -tracts or the 
" pterylography," as it is termed, -of a bird, is a valuable aid 
in doubtful cases of affinity. 

Now, if we apply these three tests to the humming-birds, 



IV HUMMING-BIRDS 833 

we find them all pointing in the same direction. The sternum 
or breast-bone is not notched behind ; and this agrees with the 
swifts, and not with the sun-birds, whose sternum has two deep 
notches behind, as in all the families of the vast order of 
Passeres to which the latter belong. The eggs of both swifts 
and humming-birds are white, only two in number, and 
resembling each other in texture. And in the arrangement 
of the feather-tracts the humming-birds approach more nearly 
to the swifts than they do to any other birds ; and altogether 
differ from the sun-birds, which in this respect, as in so many 
others, resemble the honey-suckers of Australia and other true 
passerine birds. 

BeserMcmces of Swifts and Hrnnming-Urds 

Having this clue to their affinities, we shall find other 
peculiarities common to these two groups, the swifts and the 
humming-birds. They have both ten tail-feathers, while the 
sun-birds have twelve. They have both only sixteen true 
quUl-feathers, and they are the only birds which have so 
small a number. The humming-birds are remarkable for 
having, in almost all the species, the first quill the longest of 
all, the only other birds resembling them in this respect 
being a few species of swifts; and, lastly, in both groups 
the plumage is remarkably compact and closely pressed to 
the body. Yet, with all these points of agreement, we find 
an extreme diversity in the biUs and tongues of the two 
groups. The swifts have a short, broad, flat bill, with a flat 
horny -tipped tongue of the usual character; while the 
humming-birds have a very long, narrow, almost cylindrical 
bUl, containing a tubular and highly extensible tongue. The 
essential point, however, is, that whereas hardly any of the 
other characters we have adduced are adaptive, or strictly 
correlated with habits and economy, this character is pre- 
eminently so ; for the swifts are pure aerial insect-hunters, 
and their short, broad bills and wide gape are essential to 
their mode of life. The humming-birds, on the other hand, 
are floral insect-hunters, and for this purpose their peculiarly 
long bills and extensile tongues are especially adapted ; while 
they are at the same time honey-suckers, and for this purpose 
have acquired the tubular tongue. The formation of such a 



334 TEOPICAL NATURE IV 

tubular tongue out of one of the ordinary kind is easily con- 
ceivable, as it only requires to be lengthened, and the two 
laminae of which it is composed curled in at the sides ; and 
these changes it probably goes through in the young birds. 

When on the Amazons I once had a nest brought me 
containing two little unfledged humming-birds, apparently 
not long hatched. Their beaks were not at all like those 
of their parents, but short, triangular, and broad at the base, 
just the form of the beak of a swallow or swift slightly 
lengthened. Thinking (erroneously) that the young birds 
were fed by their parents on honey, I tried to feed them with 
a syrup made of honey and water, but though they kept their 
mouths constantly open as if ravenously hungry, they would 
not swallow the liquid, but threw it out again and sometimes 
nearly choked themselves in the effort. At length I caught 
some minute flies, and on dropping one of these into the open 
mouth it instantly closed, the fly was gulped down and the 
mouth opened again for more ; and each took in this way 
fifteen or twenty little flies in succession before it was satis- 
fied. They Hved thus three or four days, but required more 
constant care than I could give them. These little birds 
were in the "swift" stage; they were pure insect-eaters, 
with a bill and mouth adapted for insect- eating only. At 
that time I was not aware of the importance of the observa- 
tion of the tongue; but as the bill was so short and the 
tubular tongue not required, there can be little doubt that 
the organ was, at that early stage of growth, short and flat, as 
it is in the birds most nearly allied to them. 

Differences between Sim-birds and Humming-birds 
In respect of all the essential and deep-seated points of 
structure, which have been shown to ofier such remarkable- 
similarities between the swifts and the humming-birds, the 
sun-birds of the Eastern hemisphere difier totally from the 
latter, while they agree with the passerine birds generally, or 
more particularly with the creepers and honey-suckers. They 
have a deeply-notched sternum ; they have twelve tail-feathers 
in place of ten ; they have nineteen quills in place of sixteen ; 
and the first quiU instead of being the longest is the very 
shortest of all, while the wings are short and round instead 



HUMMIITG-BIRDS 335 



of being excessively long and pointed; their plumage is 
arranged differently ; and their feet are long and strong, 
instead of being excessively short and weak. There remain 
only the superficial characters of small size and brilliant 
metallic colours to assimilate them with the humming-birds, 
and one structural feature — ^a tubular and somewhat extensile 
tongue. This, however, is a strictly adaptive character, the 
sun-birds feeding on small insects and the nectar of flowers, 
just as do the humming-birds ; and it is a remarkable instance 
of a highly peculiar modification of an organ occurring inde- 
pendently in two widely-separated groups. In the sun-birds 
the hyoid or tongue-muscles do not extend so completely over 
the head as they do in the humming-birds, so that the tongue 
is less extensible ; but it is constructed in exactly the same 
way by the inroIUng of the two laminae of which it is 
composed. 

The tubular tongue of the sun-birds is a special adaptive 
modification acquired within the family itself, and not 
inherited from a remote ancestral form. This is shown by 
the amount of variation this organ exhibits in different mem- 
bers of the family. It is most highly developed in the 
Arachnotherae, or spider-hunters of Asia, which are sun-birds 
without any metallic or other brilliant colouring. These 
have the longest bills and tongues, and the most developed 
hyoid muscles ; they hunt much about the blossoms of palm- 
trees, and may frequently be seen probing the flowers while 
fluttering clumsily in the air, just as if they had seen and 
attempted to imitate the aerial gambols of the American 
humming-birds. The true metallic sun-birds generally cling 
about the flowers with their strong feet; and they feed 
chiefly on minute hard insects, as do many humming-birds. 
There is, however, one species (Chalcoparia phoenicotis), 
always classed as a sun-bird, which differs entirely from the 
rest of the species in having the tongue flat, horny, and forked 
at the tip ; and its food seems to differ correspondingly, for 
small caterpillars were found in its stomach. More remotely 
allied, but yet belonging to the same family, are the little 
flower-peckers of the genus Diceum, which have a short bill 
and a tongue twice split at the end ; and these feed on small 
fruits, and perhaps on buds and on the pollen of .flowers. The 



336 TROPICAL NATURE iv 

little white-eyes (Zosterops), -which are probably allied to the 
last, eat soft fruits and minute insects. 

GonclMsion 

Here, then, we have an extensive group of birds, consider- 
ably varied in external form, yet undoubtedly closely allied 
to each other, one division jof which is specially adapted to 
feed on the juices secreted by flowers and the minute insects 
that harbour in them ; and these alone have a lengthened bill 
and double tubular tongue, just as in the humming-birds. 
We can hardly have a more striking example of the necessity 
of discriminating between adaptive and purely structural 
characters. The same adaptive character may coexist in two 
groups which have a similar mode of life, without indicating 
any affinity between them, because it may have been acquired 
by each independently to enable it to fiU a similar place in 
nature. In such cases it is found to be an almost isolated 
character, apparently connecting two groups which otherwise 
differ radically. Non-adaptive or purely structural charac- 
ters, on the other hand, are such as have probably been 
transmitted from a remote ancestor, and thus indicate funda- 
mental peculiarities of growth and development. The changes 
of structure rendered necessary by modifications of the habits 
or instincts of the different species have been made to a great 
extent independently of such characters; and as several of 
these may always be found in the same animal their value 
becomes cumulative. We thus arrive at the seeming paradox 
that the less of direct use is apparent in any peculiarity of 
structure, the greater is its value in indicating true, though 
perhaps remote, affinities ; while any peculiarity of an organ 
which seems essential to its possessor's weUbeing is often of 
very little value in indicating its affinity for other creatures. 

This somewhat technical discussion will, it is hoped, enable 
the general reader to understand some of the more important 
principles of the modern or natural classification of animals as 
distinguished from the artificial system which long prevailed. 
It will also afford him an easily remembered example of those 
principles, in the radical distinctness of two families of birds 
often confounded together, — the sun-birds of the Easterh 
Hemisphere and the humming-birds of America; and in 



IV HUMMING-BIRDS 337 

the interesting fact that the latter are essentially swifts — 
profoundly modified, it is true, for an aerial and flower- 
haunting existence, but still bearing in many important 
peculiarities of structure the unmistakable evidences of a 
common origin.^ 

^ Eeoent researches into the anatomy of the swifts and humming-birds 
have brought to light so many and such important differences that the above 
conclusion, founded on comparatively superficial characters, becomes doubtful. 
Dr. Shufeldt considers that both groups are so isolated that they each require 
to be classed as a distinct order of birds. But while the swifts are believed 
to have undoubted though remote afSnities with the swallows, it cannot yet 
be determined whether they have any real afBnity with the humming-birds, 
which latter appear to have no special and unmistakable relationship with 
any other order or family of birds. See " Studies of the Maorochires, Mor- 
phological, and otherwise, with the view of indicating their relationships," etc., 
by R. W. Shufeldt, M.D., in the Journal of the Liimean Society, vol. xx. ; 
Zoology, pp. 299, 394 : 1889. 



THE COLOURS OF ANIMALS AND SEXUAL SELECTION^ 

General Phenomena of Colour in the Organic Wovld — Theory of Heat and 
Light as producing Colour — Changes of Colour in Animals produced 
by Coloured Light — Classification of Organic Colours — Protective 
Colours — Warning Colours — Sexual Colours — Normal Colours — The 
Nature of Colour— How Animal Colours are produced — Colour a 
normal product of Organisation — Theory of Protective Colours — 
Theory of Warning Colours — Imitative Warning Colours — The Theory 
of Mimicry — Theory of Sexual Colours — Colour as a means of Recog- 
nition — Colour proportionate to Integumentary Development — Selec- 
tion by Females not a cause of Colour — Probable use of the Horns 
of Beetles — Cause of the greater Brilliancy of some Female Insects- 
Origin of the Ornamental Plumage of Male Birds — Theory of Display 
of Ornaments by Males — Natural Selection as neutralising Sexual 
Selection — Greater Brilliancy of some Female Birds — Colour-develop- 
ment as illustrated by Humming-Birds — Theory of Normal Colours — 
Local causes of Colour-development — The influence of Locality on 
Colour in ButterHies and Birds — Sense-perception influenced by Colour 
of the Integuments — Summary on Colour- development in Animals. 

General Phenomena of Colour in the Organic World 

There is probably no one quality of natural objects from 
which we derive so much pure and 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 first sketch of this essay appeared in Macmillan's Magadne of Sep- 
tember 1877. 



V COLOURS OF ANIMALS 339 

a maxvellous 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 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 contemplation brings a 
solace and enjoyment which is both intellectually and morally 
beneficial. It can then hardly excite surprise that this rela- 
tion was long thought to afibrd a sufficient explanation of the 
phenomena of colotu: ia nature ; and although the fact that 

Pull many a flower is born to blush unseen, 
And waste its sweetness on the desert air, 

might seem to throw some doubt on the sufficiency of the 
explanation, the answer was easy, — that in the progress of 
discovery man would, sooner or later, find out and enjoy 
every beauty that the hidden recesses of the earth have in 
store for him. This theory 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 1 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, it not for the contemplation and enjojrment 
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 aU 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 relation of those 
coloui's — or rather of the various rays of light — to our senses 



340 TROPICAL NATURE 



and emotions may not be another and perhaps more important 
use which they subserve in the great system of the universe ? 

We now propose to lay before our readers a general account 
of the more recent discoveries on this interesting subject ; and 
in doing so it will be necessary first to give an outline of the 
more important facts as to the colours of organised beings ; 
then to point out the cases in which it has been shown that 
colour is of use ; and lastly, to endeavour to throw some light 
on its nature and on the general laws of its development. 

Among naturalists, colour was long thought to be of little 
import, and to be quite untrustworthy as a specific character. 
The numerous cases of variability of colour led to this view. 
The occurrence of white blackbirds, white peacocks, and black 
leopards, of white blue-bells, and of white, blue, or pink milk- 
worts, led to the belief that colour was essentially unstable, 
that it could therefore be of little or no importance, and 
belonged to quite a different class of characters from form or 
structure. But it now begins to be perceived that these 
cases, though tolerably numerous, are, after all, exceptional ; 
and that colour, as a rule, is a constant character. The great 
majority of the species, both of animals and plants, are each 
distinguished by peculiar tints which vary very little, while 
the minutest markings are often constant in thousands or 
millions of individuals. All our field buttercups are invari- 
ably yellow, and our poppies red, while many of our butter- 
flies and birds resemble each other in every spot and streak of 
colour through thousands of individuals. We also find that 
colour is constant in whole genera and other groups of species. 
The Genistas are all yellow, the Erythrinas all red; many 
genera of Carabidse are entirely black ; whole families of birds 
— as the Dendrocolaptidse — are brown ; while among butter- 
flies the numerous species of Lycsena are all more or less blue, 
those of Pontia white, and those of Callidryas yellow. An ex- 
tensive survey of the organic world thus leads us to the conclu- 
sion that colour is by no means so unimportant or inconstant 
a character as at first sight it appears to be ; and the more we 
examine it the more convinced we shall become that it must 
serve some purpose in nature, and that, besides charming us 
by its diversity and beauty, it must be well worthy of our 
attentive study, and have many secrets to unfold to us. 



COLOURS OF ANIMALS 341 



Theory of Heat and Light as producing Colow 
In commencing our study of the great mass of facts 
relating to the colours of the organic world, it will be neces- 
sary to consider, first, how far the chief theories abeady 
proposed will account for them. One of the most obyious and 
most popular of these theories, and one which is still held, in 
part at least, by many eminent naturalists, is, that colour is 
due to some direct action of the heat and light of the sun — 
thus at once accounting for the great number of brilliant birds, 
insects, and flowers which are found between the tropics. 

But before proceeding to discuss this supposed explanation 
of the colours of liviag things, we must ask the preliminary 
question, — whether it is reaUy the fact that colour is more 
developed in tropical than in temperate climates in propor- 
tion to the whole number of species ; and even if we find this 
to be so, we have to inquire whether there are not so many 
and such striking exceptions to the rule as to indicate some 
other causes at work than the direct influence of solar light 
and heat. As this is a most important branch of the inquiry, 
we must go into it somewhat fully. 

It is undoubtedly the case that there are an immensely 
greater number of richly-coloured birds and insects in tropical 
than in temperate and cold countries, but it is by no means 
so certain that the proportion of coloured to obscure species is 
much or any greater. Naturalists and collectors well know 
that the majority of tropical birds are dull-coloured; and 
there are whole families, comprising hundreds of species, not 
one of which exhibits a particle of bright colour. Such are, 
for example, the Timaliidse or babbUng thrushes of the eastern, 
and the Dendrocolaptidae or tree-creepers of the western 
hemispheres. Again, many groups of birds which are imi- 
versally distributed are no more adorned with colour in the 
tropical than in the temperate zones ; such are the thrushes, 
wrens, goat-suckers, hawks, grouse, plovers, and snipe ; and if 
tropical light and heat have any direct colouring efiect, it is 
certainly most extraordinary that in groups so varied in form, 
structure, and habits as those just mentioned, the tropical 
should be in no wise distinguished in this respect from the 
temperate species. 



342 TROPICAL NATURE 



It is true that brilliant tropical birds mostly belong to 
groups which are wholly tropical — as the chatterers, toucans, 
trogons, and pittas ; but as there are perhaps an equal num- 
ber of tropical groups which are wholly dull-coloured, while 
others contain dull and bright-coloured species in nearly equal 
proportions, the evidence is by no means strong that tropical 
light and heat have anything to do with the matter. But 
there are other groups in which the cold and temperate zones 
produce finer -coloured species than the tropics. Thus the 
arctic ducks and divers are handsomer than those of the 
tropical zone ; while the king-duck of temperate America and 
the mandarin-duck of North China are the most beautifully 
coloured of the whole famUy. In the pheasant family we 
have the gorgeous gold and silver pheasants in North China 
and Mongolia, and the superb Impeyan pheasant in the tem- 
perate North- Western Himalayas, as against the peacock and 
fire-backed pheasants of tropical Asia. Then we have the 
curious fact that most of the bright- coloured birds of the 
tropics are denizens of the forests, where they are shaded 
from the direct light of the sun, and that they abound near 
the equator, where cloudy skies are very prevalent ; while, on 
the other hand, places where light and heat are at a maxi- 
mum have often dull -coloured birds. Such are the Sahara 
and other deserts, where almost all the living things are 
sand-coloured; but the most curious case is that of the Gala- 
pagos islands, situated under the equator, and not far from 
South America, where the most gorgeous colours abound, but 
which are yet characterised by prevailing dull and sombre 
tints in birds, insects, and fiowers, so that they reminded Mr. 
Darwin of the cold and barren plains of Patagonia rather 
than of any tropical country. Insects are wonderfully 
brilliant in tropical countries generally, and any one looking 
over a collection of South American or Malayan butterflies 
would scout the idea of their being no more gaily -coloured 
than the average of European species, and in this he would 
be undoubtedly right. But on examination we should find 
that all the more brilliantly-coloured groups were exclusively 
tropical, and that where a genus has a wide range there is 
little difierence in coloration between the species of cold and 
warm countries. Thus the European Vanessides, including 



V COLOURS OF ANIMALS 843 

the beautiful "peacock," "Camberwell beauty," and "red 
admiral" butterflies, are quite up to the average of tropi- 
cal colour in the same group ; and the remark will equally 
apply to the little " blues " and " coppers " ; while the alpine 
" apollo " butterflies have a delicate beauty that can hardly 
be surpassed. In other insects, which are less directly 
dependent on climate and vegetation, we find even greater 
anomalies. In the immense famUy of the Carabidse or pre- 
daceous ground-beetles, the northern forms fully equal, if 
they do not surpass, all that the tropics can produce. Every- 
where, too, in hot countries, there are thousands of obscure 
species of insects which, if they were all collected, would not 
improbably bring down the average of colour to much about 
the same level as that of temperate zones. 

But it is when we come to the vegetable world that the 
greatest misconception on this subject prevails. In abund- 
ance and variety of floral colour the tropics are almost univer- 
sally believed to be pre-eminent, not only absolutely, but 
relatively to the whole mass of vegetation and the total 
number of species. Twelve years of observation among the 
vegetation of the eastern and western tropics has, however, 
convinced me that this notion is entirely erroneous, and that, 
in proportion to the whole number of species of plants, those 
having gaily-coloured flowers are actually more abundant in 
the temperate zones than between the tropics. This will be 
found to be not so extravagant an assertion as it may at first 
appear, if we consider how many of the choicest adornments 
of our greenhouses and flower-shows are really temperate as 
opposed to tropical plants. The masses of colour produced by 
our rhododendrons, azaleas, and camellias, our pelargoniums, 
calceolarias, and cinerarias — aU strictly temperate plants — 
can certainly not be surpassed, if they can be equalled, by any 
productions of the tropics. 

It may be objected that most of the plants named are 
choice cultivated varieties, far surpassing in colour the original 
stock, while the tropical plants are mostly unvaried wild 
species. But this does not really much affect the question at 
issue. For our florists' gorgeous varieties have all been pro- 
duced under the influence of our cloudy skies, and with even 
a, still further deficiency of light, owing to the necessity of 



844 TROPICAL NATURE 



protecting them under glass from our sudden changes of 
temperature, so that they are themselves an additional proof 
that tropical light and heat are not needed for the production 
of intense and varied colour. Another important considera- 
tion is, that these cultivated varieties in many cases displace a 
number of wild species which arc hardly, if at all, cultivated. 
Thus there are scores of species of wild hollyhocks varying in 
colour almost as much as the cultivated varieties, and the 
same may be said of the pentstemons, rhododendrons, and 
many other flowers ; and if these were all brought together 
in well-grown specimens, they would produce a grand efiect. 
But it is far easier, and more profitable for our nurserymen, 
to grow varieties of one or two species, which all require a 
similar culture, rather than fifty distinct species, most of 
which would require special treatment, the result being that 
the varied beauty of the temperate flora is even now hardly 
known, except to botanists and to a few amateurs. 

But we may go further, and say that the hardy plants of 
our cold temperate zone equal, if they do not surpass, the 
productions of the tropics. Let us only remember such 
gorgeous tribes of flowers as the roses, paeordes, hollyhocks, 
and antirrhinums ; the laburnum, wistaria, and lilac ; the 
lilies, irises, and tulips ; the hyacinths, anemones, gentians, 
and poppies, and even our humble gorse, broom, and heather ; 
and we may defy any tropical country to produce masses of 
floral colour in greater abundance and variety. It may be 
true that individual tropical shrubs and flowers do surpass 
everything in the rest of the world ; but that is to be expected, 
because the tropical zone comprises a much greater land area 
than the two temperate zones, while, owing to its more 
favourable climate, it produces a still larger proportion of 
species of plants and a greater number of peculiar natural 
orders. 

Direct observation in tropical forests, plains, and mountains 
fully supports this view. Occasionally we are startled by 
some gorgeous mass of colour, but as a rule we gaze upon an 
endless expanse of green foliage, only here and there enlivened 
by not very conspicuous flowers. Even the orchids, whose 
superb blossoms adorn our stoves, form no exception to 
this rule. It is only in favoured spots that we find them in 



V COLOURS OF ANIMALS 345 

abundance ; the species with small and inconspicuous flowers 
greatly preponderate ; and the flowering season of each kind 
being of short duration, they rarely produce any marked 
efiect of colour amid the vast masses of foliage which sur- 
round them. An experienced collector in the Eastern tropics 
once told me that although a single mountain in Java had 
produced three hundred species of Orchidese, only about 2 
per cent of the whole were sufficiently ornamental or showy 
to be worth sending home as a commercial speculation. The 
Alpine meadows and rock-slopes, the open plains of the Cape 
of Good Hope or of Australia, and the flower -prairies of 
North America, offer an amount and variety of floral colour 
which can certainly not be surpassed, even if it can be 
equalled, between the tropics. 

It appears, therefore, that we may dismiss the theory that 
the development of colour in nature is directly dependent on, 
and in any way proportioned to, the amount of solar heat and 
light, as entirely unsupported by facts. Strange to say, how- 
ever, there are some rare and little-known phenomena which 
prove that in exceptional cases light does directly affect the 
colours of natural objects, and it will be as well to consider 
these before passing on to other matters. 

Changes of Golow in Animals produced ly Oolomred Light 

A few years ago Mr. T. W. Wood called attention to the 
curious changes in the colour of the chrysalis of the small 
cabbage-butterfly (Pontia rapse) when the caterpillars, just 
before their change, were confined in boxes lined with 
different tiats. Thus in black boxes they were very dark, in 
white boxes nearly white ; and he further showed that similar 
changes occurred in a state of nature, chrysalises fixed against 
a whitewashed wall being nearly white, against a red brick 
wall reddish, against a pitched paiUng nearly black. It has 
also been observed that the cocoon of the emperor-moth is 
either white or brown, according to the colours surrounding 
it. But the most extraordinary example of this kind of 
change is that furnished by the chrysalis of an African 
butterfly (Papilio Nireus), observed at the Cape by Mrs. 
Barber, and described (with a coloured plate) in the Transac- 
tions of the Entomological Society, 1874, p. 519. 



346 TROPICAL KATURE 



This caterpillar feeds upon the orange tree, and also upon 
a forest tree (Vepris lanceolata) which has a lighter green 
leaf ; and its colour corresponds with that of the leaves it 
feeds upon, being of a darker green when it feeds on the 
orange. The chrysalis is usually found suspended among the 
leafy twigs of its food-plant, or of some neighbouring tree, 
but it is probably often attached to larger branches ; and Mrs. 
Barber has discovered that it has the property of acquiring 
the colour, more or less accurately, of any natural object it 
may be in contact with. A number of the caterpillars were 
placed in a case with a glass cover, one side of the case being 
formed by a red brick wall, the other sides being of yellowish 
wood. They were fed on orange leaves, and a branch of the 
bottle -brush tree (Banksia sp.) was also placed in the case. 
When fully fed, some attached themselves to the orange 
twigs, others to the bottle-brush branch, and these all changed 
to green pupae, but each corresponded exactly in tint to the 
leaves around it, the one being dark, the other a pale faded 
green. Another attached itself to the wood, and the pupa 
became of the same yellowish colour, while one fixed itself 
just where the wood and brick joined, and became one side 
red, the other side yellow ! These remarkable changes would 
perhaps not have been credited had it not been for the pre- 
vious observations of Mr. Wood ; but the two support each 
other, and oblige us to accept them as actual phenomena. It 
is a kind of natural photography, the particular coloured rays 
to which the fresh pupa is exposed in its soft, semi-transparent 
condition effecting such a chemical change in the organic 
juices as to produce the same tint in the hardened skin. It 
is interesting, however, to note that the range of colour that 
can be acquired seems to be limited to those of natural 
objects to which the pupa is likely to be attached, for when 
Mrs. Barber surrounded one of the caterpillars with a piece 
of scarlet cloth no change of colour at all was produced, the 
pupa being of the usual green tint, but the small red spots 
with which it is marked were brighter than usual. '• 

^ Mr. E. B. Poulton has since greatly extended these observations, both in 
pupae and larvae, with very remarkable results. See Proc. of the Royal 
Society, No. 243, 1886 ; Transactions of the Royal Society, vol. clxxviii. B., 
pp. 311-441. These are briefly described in Da/rm/nism, p. 197, and more 
fully in a volume by Mr. Poulton on The Colours of Animals, 1890, 



V COLOURS OF ANIMALS 847 

Many other cases are kno-vm among insects in which the 
same species acquires a different tint according to its sur- 
roundings; this being particularly marked in some South 
African locusts, which correspond with the colour of the soil 
wherever they are found. There are also many caterpillars 
which feed on two or more plants, and which vary in colour 
accordingly. A number of such changes are quoted by Mr. 
R. Meldola, in a paper on " Variable Protective Colouring in 
Insects" (Proceedings of the Zoological Society of London, 1873, 
p. 153) ; and in some cases it has been shown that green 
chlorophyll remains unchanged in the tissues of leaf -eating 
insects, and being discernible through the transparent 
integument, produces the same colour as that of the food 
plant. 

In all these insects, as well as in the great majority of 
cases in which a change of colour occurs in other animals, the 
action is quite involuntary; but among some few of the 
higher animals the colour of the integument can be modified 
at the will of the individual, or at aU events by a reflex 
action dependent on sensation. The most remarkable case of 
this kind occurs with the chameleon, which has the power of 
changing its colour from dull white to a variety of tints. 
This singular power has been traced to two layers of movable 
pigment-ceUs deeply seated in the skin, but capable of being 
brought near to the surface. The pigment-layers are bluish 
and yellowish, and by their contraction or concentration these 
can be forced upwards either together or separately. When 
the .animal is passive the colour is dirty white, which changes 
to various tints of bluish, green, yellow, or brown, as more or 
less of either pigment is forced up and rendered visible. 
The animal is excessively sluggish and defenceless, and its 
power of changing its colour so as to harmonise with sur- 
rounding objects is essential to its safety. Here too, as with 
the pupa of Papilio Nireus, colours such as scarlet or blue, 
which do not occur in the natural environment of the animal, 
cannot be produced. Somewhat similar changes of colour 
occur in some prawns and flat-fish, according to the colour 
of the bottom on which they rest. This is very striking 
in the chameleon shrimp (Mysis chamseleon), which is 
gray when on sand, but brown or green when among sea- 



348 TROPICAL NATURE. v 

weed of ttese two colours. Experiment shows, however, 
that when blinded the change does not occur; so that 
here too we probably have a voluntary or reflex sense- 
action. 

These peculiar powers of change of colour and adaptation 
are, however, rare and quite exceptional. As a rule there is 
no direct connection between the colours of organisms and 
the kind of light to which they are usually exposed. This is 
well seen in most iishes, and in such marine animals as por- 
poises, whose backs are always dark, although this part is 
exposed to the blue and white light of the sky and clouds, 
wMle their bellies are very generally white, although these 
are constantly subjected to the deep blue or dusky green 
light from the bottom. It is evident, however, that these 
two tints have been acquired for concealment and protection. 
Looking down on the dark back of a fish it is almost invisible, 
while, to an enemy looking up from below, the light under- 
surface would be equally invisible against the light of the 
clouds and sky. Again, the gorgeous colours of the butter- 
flies which inhabit the depths of tropical forests bear no 
relation to the kind of light that falls upon them, coming as 
it does almost wholly from green foliage, dark brown soil, 
or blue skyj and the bright underwings of many moths, 
which are only exposed at night, contrast remarkably 
with the sombre tints of the upper wings, which are 
more or less exposed to the various colours of surrounding 
nature. 

Classification of Organic Colours 

We find, then, that neither the general influence of solar 
light and heat, nor the special action of variously tinted rays, 
are adequate causes for the wonderful variety, intensity, and 
complexity of the colours that everywhere meet us in the 
animal and vegetable worlds. Let us therefore take a vsdder 
view of these colours, grouping them into classes determined 
by what we know of their actual uses or special relations to 
the habits of their possessors. This, which may be termed 
the functional and biological classification of the colours of 
living organisms, seems to be best expressed by a division 
into five groups, as follows : — 



V COLOURS OF ANIMALS 349 

il. Protective colours. 
° ■ \ J. Of defenceless creatures, mimicking a. 

3, Sexual colours. 
4. Normal colours.* 
Plants 5. Attractive colours. 

It is now proposed, firstly, to point out the nature of the 
phenomena presented under each of these heads; then to 
explain the general laws of the production of colour in 
nature ; and, lastly, to show how far the varied phenomena 
of animal coloration can be explained by means of those 
laws, acting in conjunction with the laws of evolution and 
natural selection. 

Protective Oolours 

The nature of the two first groups, protective and warn- 
ing colours, has been so fully detailed and illustrated in my 
chapter on "Mimicry and other Protective Eesemblances 
among Animals," that very little need be added here except 
a few words of general explanation. Protective colours are 
exceedingly prevalent in nature, comprising those of all the 
white arctic animals, the sandy -coloured desert forms, and 
the green birds and insects of tropical forests. It also com- 
prises thousands of cases of special resemblance — of birds to 
the surroundings of their nests, and especially of insects to 
the bark, leaves, flowers, or soU, on or amid which they 
dwell. Mammalia, fishes, and reptiles, as well as mollusca 
and other marine invertebrates, present similar phenomena ; 
and the more the habits of animals are investigated, the more 
numerous are found to be the cases in which their colours 
tend to conceal them, either from their enemies or from the 
creatures they prey upon. One of the last-observed and 
most curious of these protective resemblances has been com- 
municated to me by Sir Charles Dilke. He was shown in 
Java a pink- coloured Mantis which, when at rest, exactly 
resembled a pink orchis-flower. The mantis is a carnivorous 
insect which lies in wait for its prey ; and, by its resemblance 
to a flower, the insects it feeds on would be actually attracted 
towards it. This one is said to feed especially on butter- 

' Many, or perhaps all, of these are now believed to he diversely coloured 
for purposes of recognition. See Darmnimi, p. 217. 



350 TROPICAL NATURE 



flies, so that it is really a living trap, and forms its own 
bait ! 1 

All wlio have observed animals, and especially insects, in 
their native haunts and attitudes, can understand how it is 
that an insect which in a cabinet looks exceedingly con- 
spicuous, may yet when alive, in its peculiar attitude of 
repose and with its habitual surroundings, be perfectly well 
concealed. We can hardly ever tell by the mere inspection 
of an animal whether its colours are protective or not. No 
one would imagine the exquisitely beautiful caterpillar of the 
emperor-moth, which is green with pink star-like spots, to be 
protectively coloured; yet, when feeding on the heather, it 
so harmonises with the foliage and flowers as to be almost 
invisible. Every day fresh cases of protective colouring are 
being discovered, even in our own country; and it is becoming 
more and more evident that the need of protection has played 
a very important part in determining the actual coloration 
of animals. 

Wa/rnmg Colours 

The second class — ^the warning colours — are exceedingly 
interesting, because the object and effect of these is, not to 
conceal the object, but to make it conspicuous. To these 
creatures it is useful to be seen and recognised ; the reason 
being that they have a means of defence which, if known, 
will prevent their enemies from attacking them, though it is 
generally not suflBcient to save their lives if they are actually 
attacked. The best examples of these specially protected 
creatures consist of two extensive families of butterflies, the 
Danaidse and Acrseidse, comprising many hundreds of species 
inhabiting the tropics of all parts of the world. These 
insects are generally large, are all conspicuously and often 
most gorgeously coloured, presenting almost every conceivable 
tint and pattern ; they all fly slowly, and they never attempt 
to conceal themselves ; yet no bird, spider, lizard, or monkey 
(all of which eat other butterflies) ever devours them. The 
reason simply is that they are not fit to eat, their juices 
having a powerful odour and taste that is absolutely dis- 
gusting to all these animals. Now we see the reason of their 

^ These cases form a distinct snb-group of "alluring coloration." See 
Daniiiniam, p. 210. 



V COLOURS OF ANIMALS 351 

showy colours and slow flight. It is good for them to be 
seen and recognised, for then they are never molested ; but 
if they did not differ in form and colouring from other 
butterflies, or if they flew so quickly that their peculiarities 
could not be easily noticed, they would be captured, and 
though not eaten would be maimed or killed. 

As soon as the cause of the peculiarities of these butterflies 
was clearly recognised, it was seen that the same explanation 
applied to many other groups of animals. Thus, bees and 
wasps and other stinging insects are showily and distinctively 
coloured ; many soft and apparently defenceless beetles, and 
many gay-coloured moths, were found to be as nauseous as the 
above-named butterflies ; other beetles, whose hard and glossy 
coats of mail render them unpalatable to insect-eating birds, 
are also sometimes showily coloured ; and the same rule was 
found to apply to caterpillars, all the brown and green (or 
protectively coloured species) being greedily eaten by birds, 
while showy kinds which never hide themselves — like those 
of the magpie-, mullein-, and burnet-moths — were utterly 
refused by insectivorous birds, lizards, frogs, and spiders 
(p. 84). Some few analogous examples are found among 
vertebrate animals. I will only mention here a very interest- 
ing case not given in my former work. In his delightful 
book, entitled The Natwralist in Nicaragua, Mr. Belt tells us 
that there is in that country a frog which is very abundant, 
which hops about in the day-time, which never hides him- 
self, and which is gorgeously coloured with red and blue. 
Now frogs are usually green, brown, or earth-coloured, feed 
mostly at night, and are all eaten by snakes and birds. 
Having full faith in the theory of protective and warning 
colours, to which he had himself contributed some valuable 
facts and observations, Mr. Belt felt convinced that this frog 
must be uneatable. He therefore took one home, and threw 
it to his ducks and fowls ; but all refused to touch it except 
one young duck, which took the frog in its mouth, but 
dropped it directly, and went about jerking its head as if 
trying to get rid of something nasty. Here the uneatableness 
of the frog was predicted from its colours and habits, and we 
can have no more convincing proof of the truth of a theory 
than such previsions. 



362 TROPICAL NATURE 



The universal avoidance by carnivorous animals of all 
these specially protected groups, which are thus entirely free 
from the constant persecution suffered by other creatures not 
so protected, would evidently render it advantageous for 
any of these latter which were subjected to extreme persecu- 
tion to be mistaken for the former ; and for this purpose it 
would be necessary that they should have the same colours, 
form, and habits. Now, strange to say, wherever there is 
a large group of directly-protected forms (division a of animals 
with warning colours), there are sure to be found a few other- 
wise defenceless creatures which resemble them externally so 
as to be mistaken for them, and which thus gain protection, 
as it were, on false pretences (division b of animals with 
warning colours). This is what is called " mimicry," and it 
has already been very fully treated of by Mr. Bates (its dis- 
coverer), by myself, by Mr. Trimen, and others. Here it is 
only necessary to state that the uneatable Danaidse and 
Acrseidae are accompanied by a few species of other groups 
of butterflies (Leptalidae, Papilios, Diademas, and Moths), 
which are all really eatable, but which escape attack by their 
close resemblance to some species of the uneatable groups 
found in the same locality. In like manner there are a few 
eatable beetles which exactly resemble species of uneatable 
groups ; and others, which are soft, imitate those which are 
uneatable through their hardness. For the same reason 
wasps are imitated by moths, and ants by beetles ; and even 
poisonous snakes are mimicked by harmless snakes, and 
dangerous hawks by defenceless cuckoos. How these curious 
imitations have been brought about, and the laws which 
govern them, have been already discussed. (See p. 54.) 

Sexual Golowrs 

The third class comprises all cases in which the colours of 
the two sexes differ. This difference is very general, and 
varies greatly in amount, from a slight divergence of tint up 
to a radical change of coloration. Differences of this kind 
are found among all classes of animals in which the sexes are 
separated, but they are much more frequent in some groups 
than in others. In mammalia, reptiles, and fishes, they are 



V COLOURS OF ANIMALS 353 

comparatively rare and not great in amount, whereas among 
birds they are very frequent and very largely developed. So 
among insects, they are abundant in butterflies, whUe they are 
comparatively uncommon in beetles, wasps, and hemiptera. 

The phenomena of sexual variations of colour, as well as of 
colour generally, are wonderfully similar in the two analogous 
yet totally unrelated groups of birds and butterflies j and as 
they both offer ample materials, we shall confine our study of 
the subject chiefly to them. The most common case of differ- 
ence of colour between the sexes is for the male to have the 
same general hue as the females, but deeper and more intensi- 
fied — as in many thrushes, finches, and hawks, and among 
butterflies in the majority of oiu- British species. In cases 
where the male is smaller the intensification of colour is 
especially well pronounced — as in many of the hawks and 
falcons, and in niost butterflies and moths in which the 
coloration does not materially differ. In another extensive 
series we have spots or patches of vivid colour in the male, 
which are represented in the female by far less brilliant tints 
or are altogether wanting — as exemplified in the gold-crest 
warbler, the green woodpecker, and most of the orange-tip 
butterflies (Anthocharis). Proceeding with our survey, we 
find greater and greater difierences of colour in the sexes, tiU 
we arrive at such extreme cases as some of the pheasants, the 
chatterers, tanagers, and birds-of-paradise, in which the male 
is adorned with the most gorgeous and vivid colours, while 
the female is usually duU brown, or olive green, and often 
shows no approximation whatever to the varied tints of her 
partner. Similar phenomena occur among butterflies ; and in 
both these groups there are also a considerable number of 
cases in which both sexes are highly but differently coloured. 
Thus many woodpeckers have the head in the male red, in 
the female yellow ; while some parrots have red spots in the 
male, replaced by blue in the female, as in Psittacula diop- 
thalma. In many South American Papilios, green spots on 
the male are represented by red on the female j and in several 
species of the genus EpicaHa, orange bands in the male are 
replaced by blue in the female, a similar change of colour to 
that in the small parrot above referred to. For fuUer details 
of the varieties of sexual coloration we refer our readers to 

2 A 



354 TROPICAL NATURE 



Mr. Darwin's Descent of Mem, chapters x. to xviii., and to 
chapters iii. iv. and vii. of the first portion of the present 
volume. 

Normal Colours 

The fourth group — of normally coloured animals — ^includes 
all species which are brilliantly or conspicuously coloured in 
both sexes, and for whose particular colours we can assign no 
function or use.'' It comprises an immense number of showy 
birds, such as kingfishers, barbets, toucans, lories, tits, and 
starlings ; among insects most of the largest and handsomest 
butterflies, innumerable bright-coloured beetles, locusts, dragon- 
flies, and hymenoptera ; a few mammalia, as the zebras ; a 
great number of marine fishes ; thousands of striped and 
spotted caterpillars ; and abundance of moUusca, star-fish, and 
other marine animals. Among these we have included some 
which, like the gaudy caterpillars, have warning colours ; but 
as that theory does not explain the particular colours or the 
varied patterns with which they are adorned, it is best to 
include them also in this class. It is a suggestive fact that 
all the brightly-coloured birds mentioned above build in holes 
or form covered nests, so that the females do not need that 
protection during the breeding season which I believe to be 
one of the chief causes of the dull colour of female birds when 
their partners are gaily coloured. This subject is fully argued 
in chapter vi. of the present volume. 

Leaving the colours of flowers to be discussed in another 
chapter, we will now consider how the general facts of colour 
here sketched out can be explained. We have first to inquire 
what is colour, and how it is produced; secondly, what is 
known of the causes of change of colour ; and, lastly, what 
theory best accords with the whole assemblage of facts. 

The Nature of Colow 

The sensation of colour is caused by vibrations or undula- 
tions of the ethereal medium of different lengths and velocities. 
The whole body of vibrations caused by the sun is termed 

' Distinctness of marking for purposes of recognition is probably the use 
in all cases. See p. 367, and Darwinism, p. 217. 



V COLOURS OF ANIMALS 355 

radiation, or, more commonly, rays; and consists of sets of 
waves wMck vary considerably in their dimensions and rate 
of recurrence, but of which the middle portion only is capable 
of exciting in us sensations of light and colour. Beginning 
with the largest waves, which recur at the longest intervals, 
we have first those which produce heat-sensations only ; as 
they get smaller and recur quicker, we perceive a dull red 
colour ; and as the waves increase in rapidity and diminish in 
size, we get successively sensations of orange, yeUow, green, 
blue, indigo, and violet, all fading imperceptibly into each 
other. Then come more invisible rays, of shorter wave- 
length and quicker recurrence, which produce, solely or 
chiefly, chemical effects. The red rays, which first become 
visible, have been ascertained to recur at the rate of 458 
millions of milliQns times in a second, the length of each wave 
^eiing aeaoo ^^ *^ ^'^^ > 'while the violet rays, which last 
remain visible, recur 727 millions of millions times per second, 
and have a wave-length of g^^j^g of an inch. Although the 
waves recur at difierent rates, they are all propagated through 
the ether with the same velocity (192,000 miles per second) ; 
just as different musical sounds, which are produced by 
waves of air of different lengths and rates of recurrence, travel 
at the same speed, so that a tune played several hundred 
yards off reaches the ear in correct time. There are, there- 
fore, an almost infinite number of different colour-producing 
undulations, and these may be combined in an almost infinite 
variety of ways, so as to excite in us the sensation of aU the 
varied colours and tints we are capable of perceiving. When 
all the different kinds of rays reach us in the proportion in 
which they exist in the light of the sun, they produce the 
sensation of white. If the rays which excite the sensation of 
any one colour are prevented from reaching us, the remaining 
rays in combination produce a sensation of colour often very 
far removed from white. Thus green rays being abstracted 
leave purple light; blue, orange-red light; violet, yellowish- 
green light, and so on. These pairs are termed comple- 
mentary colours. And if portions of differently coloured 
lights are abstracted in various degrees, we have produced all 
those infinite gradations of colours, and all those varied tints 
and hues which are of such use to us in distinguishing 



356 TROPICAL NATURE 



external objects, and which form one of the great charms of 
our existence. Primary colours would therefore be as 
numerous as the different wave-lengths of the visible radia- 
tions, if we could appreciate all their differences; while 
secondary or compound colours, caused by the simultaneous 
action of any combination of rays of different wave-lengths, 
must be still more numerous. 

In order to account for the fact that all colours appear to 
us to be produced by combinations of three primary colours 
— red, green, and violet — it is believed that we have three 
sets of nerve fibres in the retina, each of which is capable of 
being excited by all rays, but that one set is excited most by 
the larger or red waves, another by the medium or green 
waves, and the third set chiefly by the violet or smallest 
waves of light ; and when all three sets are excited together 
in proper proportions we see white. This view is supported 
by the phenomena of colour-blindness, which are explicable on 
the theory that one of these sets of nerve-fibres (usually that 
adapted to perceive red) has lost its sensibility, causing all 
colours to appear as if the red rays were abstracted from 
them. 

It is a property of these various radiations that they are 
unequally refracted or bent in passing obliquely through 
transparent bodies, the longer waves being least refracted, the 
shorter most. Hence it becomes possible to analyse white or 
any other light into its component rays. A small ray of 
sunlight, for example, which would produce a white spot 
on a wall, if passed through a prism, is lengthened out into a 
band of coloured light, exactly corresponding to the colours of 
the rainbow. Any one colour can thus be isolated and 
separately examined ; and by means of reflecting mirrors the 
separate colours can be again compounded in various ways, 
and the resvdting colours observed. This band of coloured 
light is called a spectrum, and the instrument by which the 
spectra of various kinds of light are examined is called a 
spectroscope. This branch of the siibject has, however, no 
direct bearing on the mode in which the colours of living 
things are produced, and it has only been alluded to in order 
to complete our sketch of the nature of colour. 

The colours which we perceive in material substances are 



V COLOUES OF ANIMALS 357 

produced either by the absorption or by the interference of 
some of the rays which form white light. Pigmental or 
absorption-colours are the most frequent, comprising all the 
opaque tints of flowers and insects, and all the colours of dyes 
and pigments. They are caused by rays of certain wave- 
lengths being absorbed, while the remaining rays are reflected 
and give rise to the sensation of colour. When all the colour- 
producing rays are reflected in due proportion, the colour of 
the object is white ; when all are absorbed the colour is black. 
If blue rays only are absorbed the resulting colour is orange- 
red ; and generally, whatever colour an object appears to us, 
it is because the complementary colours are absorbed by it. 
The reason why rays of only certain refrangibilities are re- 
flected, and the rest of the incident light absorbed by each 
substance, is supposed to depend upon the molecular structure 
of the body. Chemical action almost always implies change 
of molecular structure; hence chemical action is the most 
potent cause of change of colour. Sometimes simple solution 
in water efiects a marvellous change, as in the case of' the 
well-known aniline dyes; the magenta and violet dyes 
exhibiting, when in the solid form, various shades of golden 
or bronzy metallic green. 

Heat alone often produces change of colour without efiect- 
ing any chemical change. Mr. Ackroyd has investigated this 
subject,^ and has sho«m that a large number of bodies are 
changed by heat, returning to their normal colour when 
cooled, and that this change is almost always in the direction 
of the less refrangible rays or longer wave-lengths; and he 
connects the change with the molecular expansion caused by 
heat. As examples may be mentioned mercuric oxide, which 
is orange yellow, but which changes to orange, red, and brown 
when heated ; chromic oxide, which is green, and changes to 
yellow ; cinnabar, which is scarlet, and changes to puce ; and 
metaborate of copper, which is blue, and changes to green 
and greenish yellow. 

How Animal Colours are Produced 

The colouring matters of animals are very varied. Copper 
has been found in the red pigment of the wing of the turaco, 

^ " Metachromatism, or Colour-Cliange," Chemical Neics, August 1876. 



358 TROPICAL NATURE 



and Mr. Sorby has detected no less than seven distinct 
colouring matters in birds' eggs, several of which are chem- 
ically related to those of blood and bile. The same colours 
are often produced by quite different substances in different 
groups, as shown by the red of the wing on the burnet-moth 
changing to yellow with muriatic acid, while the red of the 
red-admiral butterfly undergoes no such change. 

These pigmental colours have a different character in 
animals according to their position in the integument. Fol- 
lowing Dr. Hagen's classification, epidermal colours are those 
which exist in the external chitinised skin of insects, in the 
hairs of mammals, and, partially, in the feathers of birds. 
They are often very deep and rich, and do not fade after 
death. The hypodermal colours are those which are situated 
in the inferior soft layer of the skin. These are often of 
lighter and more vivid tints, and usually fade after death. 
Many of the reds and yellows of butterflies and birds belong 
to this class, as well as the intensely vivid hues of the naked 
skin about the heads of many birds. These pigments some- 
times exude through the pores, forming an evanescent bloom 
on the surface. 

Interference colours are less frequent in the organic world. 
They are caused in two ways : either by reflection from the 
two surfaces of transparent films, as seen in the soap-bubble 
and in thin films of oil on water ; or by fine strise which pro- 
duce colours either by reflected or transmitted Hght, as seen 
in mother-of-pearl and in flnely-ruled metalHc surfaces. In 
both cases colour is produced by light of one wave-length 
being neutralised, owing to one set of such waves being 
retarded or shifted so as to be half a wave-length behind the 
other set, as may be found explained in any treatise on 
physical optics. The result is, that the complementary colour 
of that neutralised is seen ; and, as the thickness of the film or 
the fineness of the strise undergo slight changes, almost any 
colour can be produced. This is believed to be the origin of 
many of the glossy or metallic tints of insects, as well as 
those of the feathers of some birds. The iridescent colours of 
the wings of dragon-flies are caused by the superposition of 
two or more transparent lamellss ; while the shining blue of 
the purple-emperor and other butterflies, and the intensely 



V COLOURS OF ANIMALS 359 

metallic colours of humming-birds, are probably due to fine 
striae. 

Colour a Normal Product of Organisation 

This outline sketch of the nature of colour in the animal 
world, however imperfect, will at least serve to show us how 
numerous and varied are the causes which perpetually tend 
to the production of colour in animal tissues. If we consider 
that in order to produce white all the rays which fall upon an 
object must be reflected in nearly the same proportions as 
they exist in solar light — whereas, if rays of any one or more 
kinds are absorbed or neutralised, the resultant reflected light 
will be coloured ; and that this colour may be infinitely 
varied according to the proportions in which different ray^ are 
reflected or absorbed — we should expect that white would be, 
as it really is, comparatively rare and exceptional in nature.^ 
The same observation will apply to black, which arises from 
the absorption of all the different rays. Many of the com- 
plex substances which exist in animals and plants are subject 
to changes of colour under the influence of light, heat, 
or chemical change, and we know that chemical changes 
are continually occurring during the physiological processes 
which occur in the body during development and growth. 
We also find that every external character is subject to 
minute changes, which are generally perceptible to us in 
closely allied species ; and we can therefore have no doubt 
that the extension and thickness of the transparent lamellae, 
and the fineness of the strise or rugosities of the integuments, 
must be undergoing constant minute changes; and these 
changes wiU very frequently produce changes of colour. These 
considerations render it probable that colour is a normal and 
even necessary result of the complex structure of animals and 
plants ; and that those parts of an organism which are under- 
going continual development and adaptation to new conditions, 
and are also continually subject to the action of light and heat, 
will be the parts in which changes of colour will most fre- 
quently appear. Now there is little doubt that the external 
changes of animals and plants in adaptation to the environ- 

^ Wliite is produced by the scattering of the Tarious rays in all directions, 
and is often caused by air-bubbles or transparent globules. See Poulton's 
Colours of Animals, pp. 3-6. 



360 TROPICAL NATURE 



ment are much more numerous than the internal changes ; as 
seen in the varied character of the integuments and append- 
ages of animals^hair, horns, scales, feathers, etc., etc. — and 
in plants, the leaves, bark, flowers, and fruit, ■with their 
various modiiications — as compared with the great uniformity 
in the texture and composition of their internal tissues ; and 
this accords with the uniformity of the tints of blood, muscle, 
nerve, and bone throughout extensive groups, as compared 
with the great diversity of colour of their external organs. 
It seems a fair conclusion that colour per se may be considered 
to be normal, and to need no special accounting for ; while 
the absence of colour (that is, either white or black), or the 
prevalence of certain colours to the constant exclusion of 
others, must be traced, like other modiiications in the 
economy of living things, to the needs of the species. Or, 
looking at it in another aspect, we may say that amid the 
constant variations of animals and plants colour is ever tend- 
ing to vary and to appear where it is absent ; and that natural 
selection is constantly eliminating such tints as are injurious 
to the species, or preserving and intensifying such as are 
useful. 

This view is in accordance with the weU- known fact of 
colours which rarely or never appear in the species in a 
state of nature, continually occurring among domesticated 
animals and cultivated plants ; showing us that the capacity 
to develop colour is ever present, so that almost any required 
tint can be produced which may, under changed conditions, 
be useful, in however small a degree. 

Let us now see how these principles will enable us to 
understand and explain the varied phenomena of colour in 
nature, taking them in the order of our functional classifica- 
tion of colours. 

Theory of Protective Colomrs 
We have seen that obscure or protective tints in their 
infinitely varied degrees are present in every part of the 
animal kingdom ; whole families or genera being often thus 
coloured. Now the various brown, earthy, ashy, and other 
neutral tints are those which would be most readily produced, 
because they are due to an irregular mixture of many kinds 



V COLOURS OF ANIMALS 361 

of rays ; while pure tints require either rays of one kind only, 
or definite mixtures in proper proportions of two or more 
kinds of rays. This is well exemplified by the comparative 
difficulty of producing definite pure tints by the mixture of 
two or more pigments ; while a haphazard mixture of a 
number of these wiU be almost sure to produce browns, olives, 
or other neutral or dingy colours. An indefinite or irregular 
absorption of some rays and reflection of others would, there- 
fore, produce obscure tints; while pure and vivid colours 
would require a perfectly definite absorption of one portion 
of the coloured rays, leaving the remainder to produce the 
true complementary colour. This being the case, we may 
expect these brown tints to occur when the need of protection 
is very slight or even when it does not exist at all ; always 
supposing that bright colours are not in any way useful to 
the species. But whenever a pure colour is protective, — as 
green in tropical forests, or white among arctic snows, — there 
is no difficulty in producing it, by natural selection acting on 
the innumerable slight variations of tint which are ever occur- 
ing. Such variations may, as we have seen, be produced in 
a great variety of ways, either by chemical changes in the 
secretions, or by molecular changes in surface structure ; and 
may be brought about by change of food, by the physiological 
action of light, or by the normal process of generative varia- 
tion. Protective colours therefore, however curious and com- 
plex they may be in certain cases, ofiier no real difficulties. 

Theory of Warning Colows 

These di£Fer greatly from the last class, inasmuch as they 
present us with a variety of brilliant hues, often of the 
greatest purity, and combined in striking contrasts and 
conspicuous patterns. Their use depends upon their bold- 
ness and visibility, not on the presence of any one colour ; 
hence we find among these groups some of the most ex- 
quisitely-coloured objects in nature. Many of the uneatable 
caterpillars are strikingly beautiful; while the Danaidae, 
Heliconidse, and protected groups of PapUionidae, comprise a 
series of butterflies of the most brilliant and contrasted 
colours. The bright colours of many of the sea-anemones 
and sea -slugs will probably be found to be in this sense 



362 TROPICAL NATURE 



protective, serving as a warning of their uneatableness.^ On 
our theory none of these colours offer any difficulty. Con- 
spicuousness being useful, every variation tending to brighter 
and purer colours was selected ; the result being the beautiful 
variety and contrast we find. 

Imitative Warning Colours — the Theory of Mimicry 

We now come to those groups which gain protection solely 
by being mistaken for some of these brilliantly coloured but 
uneatable creatures, and here a difficulty really exists, and to 
many minds is so gi-eat as to be insuperable. It will be well 
therefore to endeavour to explain how the resemblance in 
question may have been brought about. 

The most difficult case, and the one which may be taken 
as a type of the whole class, is that of the genus Leptalis (a 
group of South American butterflies allied to our common 
white and yellow kinds), many of the larger species of which 
are still white or yellow, and which are all eatable by birds 
and other insectivorous creatures. But there are also a 
number of species of Leptalis, which are brilliantly red, 
yellow, and black, and which, band for band and spot for 
spot, resemble some one of the Danaidae or Heliconidse which 
inhabit the same district and which are nauseous and uneat- 
able. Now the usual difficulty is, that a slight approach to 
one of these protected butterflies would be of no use, while a 
greater sudden variation is not admissible on the theory of 
gradual change by indefinite slight variations. This objection 
depends almost wholly on the supposition that, when the first 
steps towards mimicry occurred, the South American Danaidse 
were what they are now ; while the ancestors of the Leptalides 
were like the ordinary white or yellow Pieridse to which they 
are allied. But the Danaioid butterflies of South America are 
so immensely numerous and so greatly varied, not only in colour 
but in structure, that we may be sure they are of vast antiquity 
and have undergone great modification. A large number of 
them, however, are still of comparatively plain colours, often 
rendered extremely elegant by the delicate transparency of 
the wing membrane, but otherwise not at all conspicuous. 

^ This has since teen found to be the case by Professor Herdman ( Trans. 
Biol. Soc. Liverpool, vol. iv. p. 150). 



V COLOURS OF ANIMALS 363 

Many have only dusky or purplish bands or spots; others 
have patches of reddish or yellowish brown — perhaps the 
commonest colour among butterflies ; while a considerable 
number are tinged or spotted with yellow, also a very common 
colour, and one especially characteristic of the Pieridee, the 
family to which Leptalis belongs. We may therefore reason- 
ably suppose that in the early stages of the development of 
the Danaidse, when they first began to acquire those nauseous 
secretions which are now their protection, their colours were 
somewhat plain ; either dusky with paler bands and spots, or 
yellowish with dark borders, and sometimes with reddish 
bands or spots. At this time they had probably shorter 
wings and a more rapid flight, just like the other unprotected 
families of butterflies. But, so soon as they became decidedly 
unpalatable to any of their enemies, it would be an advantage 
to them to be readily distinguished from all the eatable kinds ; 
and as butterflies were no doubt already very varied in colour, 
while all probably had wings adapted for rather quick or 
jerking flight, the best distinction might have been found in 
outline and habits ; whence would arise the preservation of 
those varieties whose longer wings, bodies, and antennse, as 
well as their slower flight, rendered them noticeable — 
characters which now distinguish the whole group in every 
part of the world. 

Now it would be at this stage that some of the weaker- 
flying Pieridse which happened to resemble some of the 
Danaidae around them in their yellow and dusky tints and in 
the general outline of their wings, would be sometimes mis- 
taken for them by the common enemy, and would thus gain 
an advantage in the struggle for existence. Admitting this 
one step to be made, and all the rest must inevitably foUow 
from simple variation and survival of the fittest. So soon as 
the nauseous butterfly varied in form or colour to such an 
extent that the corresponding eatable butterfly no longer 
closely resembled it, the latter would be exposed to attacks, 
and only those variations would be preserved which kept up 
the resemblance. At the same time we may well suppose the 
enemies to become more acute and able to detect smaller 
differences than at first. This would lead to the destruction 
of all adverse variations, and thus keep up in continually 



364 TROPICAL NATUEE 



increasiBg complexity the outward mimicry ■which now so 
amazes us. During the long ages in which this process has 
been going on, and the Danaidse have been acquiring those 
specialities of colour which aid in their preservation, many a 
Leptalis may have become extinct from not varying suffi- 
ciently in the right direction and at the right time to keep 
up a protective resemblance to its neighbour ; and this well 
accords with the comparatively small number of cases of true 
mimicry, as compared with the frequency of those protective 
resemblances to vegetable or inorganic objects whose forms 
are less definite and colours less changeable. About a dozen 
other genera of butterflies and moths mimic the Danaidse in 
various parts of the world, and exactly the same explanation 
will apply to all of them. They represent those species of 
each group which, at the time when the Danaidse first 
acquired their protective secretions, happened outwardly to 
resemble some of them, and which have, by concurrent varia- 
tion aided by a rigid selection, been able to keep up that 
resemblance to the present day.^ 

Theory of Sexual Colows 

In Mr. Darwin's celebrated work. The Descent of Man and 
Selection in Relation to Sex, he has treated of sexual colour in 
combination with other sexual characters, and has arrived at 
the conclusion that all or almost all the colours of the higher 
animals (including among these insects and all vertebrates) 
are due to voluntary or conscious sexual selection ; and that 
diversity of colour in the sexes is due, primarily, to the trans- 
mission of colour-variations either to one sex only or to both 
sexes, the difiference depending on some unknown law, and 
not being due to natural selection. 

I have long held this portion of Mr. Darwin's theory to be 
erroneous, and have argued that the primary cause of sexual 
diversity of colour was the need of protection, repressing in 

^ For fuller information on this sutjeot the reader should consult Mr. 
Bates' original paper, "Contributions to an Insect -fauna of the Amazon 
Valley," in Transactions of the Linnean Society, vol. xxiii. p. 495 ; Mr. 
Trimen's paper in vol. xxvi. p. 497 ; the author's essay on "Mimicry," etc., 
already referred to ; and, in the absence of collections of butterflies, the plates 
of Heliconidse and Leptalidae, in Hewitson's Exotic Butterflies ; and Feldei''s 
Voyage of the " Novara," may be examined. 



V COLOURS OF ANIMALS 365 

the female those bright colours which are normally produced 
in both sexes by general laws ; and I have attempted to 
explain many of the more difficult cases on this principle 
("A Theory of Birds' Nests," chap. vi. awfe). As I have 
since given much thought to this subject, and have arrived 
at some views which appear to me to be of considerable im- 
portance, it will be well to sketch briefly the theory I now hold, 
and afterwards show its application to some of the detailed 
cases adduced in Mr. Darwin's work. 

The very frequent superiority of the male bird or insect 
in brightness or intensity of colour, even when the general 
coloration is the same in both sexes, now seems to me to be, 
in great part, due to the greater vigour and activity and the 
higher vitality of the male. The colours of an animal usually 
fade during disease or weakness, while robust health and 
vigour adds to their intensity. This is a most important and 
suggestive fact, and one that appears to hold universally. In 
all quadrupeds a " dull coat " is indicative of ill-health or low 
condition, while a glossy coat and sparkling eye are the 
invariable accompaniments of health and vital activity. The 
same rule applies to the feathers of birds, whose colours are 
only seen in their purity during perfect health ; and a similar 
phenomenon occurs even among insects, for the bright hues 
of caterpUlars begin to fade as soon as they become inactive 
preparatory to undergoing their transformation, or if attacked 
by disease. Even in the vegetable kingdom we see the same 
thing, for the tints of foliage are deepest, and the colours of 
flowers and fruits richest, on those plants which are in the 
most healthy and vigorous condition. 

This intensity of coloration becomes most developed in the 
male during the breeding season, when the vitality is at a 
maximum. It is also very general in those cases in which 
the male is smaller than the female, as in the hawks and in 
most butterflies and moths. The same phenomena occur, 
though in a less marked degree, among mammalia. When- 
ever there is a difierence of colour between the sexes the 
male is the darker or more strongly marked, and the differ- 
ence of intensity is most visible during the breeding season 
(Descent of Man, p. 533). Numerous cases among domestic 
animals also prove that there is an inherent tendency in the 



366 TROPICAL NATURE 



male to special developments of dermal appendages and colour, 
quite independently of sexual or any other form of selection. 
Thus — " the hump on the male zebu cattle of India, the tail 
of fat-tailed rams, the arched outline of the forehead in the 
males of several breeds of sheep, and the mane, the long hairs 
on the hind legs, and the dewlap of the male of the Berbura 
goat " — are all adduced by Mr. Darwin as instances of char- 
acters peculiar to the male, yet not derived from any parent 
ancestral form. Among domestic pigeons the character of 
the different breeds is often most strongly manifested in the 
male birds ; the wattles of the carriers and the eye- wattles of 
the barbs are largest in the males, and male pouters distend 
their crops to a much greater extent than do the females, 
while the cock fantails often have a greater number of tail- 
feathers than the females. There are also some varieties of 
pigeons of which the males are striped or spotted with black, 
while the females are never so spotted (Animals and Plants 
vmder Domestication, i. 161) ; yet in the parent stock of these 
pigeons there are no differences between the sexes either of 
plumage or colour, and artificial selection has not been applied 
to produce them. 

The greater intensity of coloration in the male, which may 
be termed the normal sexual difference, would be further 
developed by the combats of the males for the possession of 
the females. The most vigorous and energetic usually being 
able to rear most offspring, intensity of colour, if dependent 
on, or correlated with vigour, would tend to increase. But 
as differences of colour depend upon minute chemical or 
structural differences in the organism, increasing vigour acting 
unequally on different portions of the integument, and often 
producing at the same time abnormal developments of hair, 
horns, scales, feathers, etc., would almost necessarily lead also 
to variable distribution of colour, and thus to the production 
of new tints and markings. These acquired colours would, 
as Mr. Darwin has shown, be transmitted to both sexes or 
to one only, according as they first appeared at an early age, 
or in adults of one sex ; and thus we may account for some 
of the most marked differences in this respect. With the 
exception of butterflies, the sexes are almost alike in the 
great majority of insects. The same is the case in mammals 



V COLOURS OF ANIMALS 367 

and reptiles, while the chief departure from the rule occurs 
in birds, though even here in very many cases the law of 
sexual likeness prevails. But in all cases where the increas- 
ing development of colour became disadvantageous to the 
female, it would be checked by natural selection, and thus 
produce those numerous instances of protective colouring in 
the female only, which occur most frequently in these two 
groups, birds and butterflies. 

Colowr as a means of Recognition 

There is also, I believe, a very important purpose and use 
of the varied colours of the higher animals in the facility it 
affords for recognition by the sexes or by the young of the 
same species; and it is this use which probably fixes and 
determines the coloration in many cases. When diflferences 
in the size and form of allied species are very sKght, colour 
affords the only means of recognition at a distance, or while 
in motion; and such a distinctive character must therefore 
be of especial value to flying insects which are continually in 
motion, and encounter each other, as it were, by accident. 
This view offers us an explanation of the curious fact that 
among butterflies the females of closely-aUied species in the 
same locality sometimes differ considerably, while the males 
are much alike ; for, as the males are the swiftest and by far 
the highest fliers, and seek out the females, it would evidently 
be advantageous for them to be able to recognise their true 
partners at some distance off. This peculiarity occurs with 
many species of PapiUo, Diadema, AdoKas, and CoHas; and 
these are all genera, the males of which are strong on the 
wing and mount high in the air. In birds such marked 
differences of colour are not required owing to their higher 
organisation and more perfect senses, which render recogni- 
tion easy by means of a combination of very slight differential 
characters. "^ 

This principle may perhaps, however, account for some 
anomalies of coloration among the higher animals. Thus, 
while admitting that the hare and the rabbit are coloiu-ed 
protectively, Mr. Darwin remarks that the latter, while 

^ For numerous examples of recognition-colours in birds, see Danmnism, 
pp. 217-226. 



TROPICAL NATURE 



running to its burrow, is made conspicuous to the sportsman, 
and no doubt to all beasts of prey, by its upturned white tail. 
But this very conspicuousness while running away, may be 
useful as a signal and guide to the young, who are thus 
enabled to escape danger by following the older rabbits, 
directly and without hesitation, to the safety of the burrow ; 
and this may be the more important from the semi-nocturnal 
habits of the animal. If this explanation is correct, and it 
certainly seems probable, it may serve as a warning of how 
impossible it is, without exact knowledge of the habits of an 
animal and a full consideration of all the circumstances, to 
decide that any particular coloration cannot be protective or 
in any way useful. Mr. Darwin himself is not free from such 
assumptions. Thus, he says : — " The zebra is conspicuously 
striped, and stripes cannot afford any protection on the open 
plains of South Africa." But the zebra is a very swift 
animal, and, when in herds, by no means void of means of 
defence. The stripes therefore moA/ be of use by enabling 
stragglers to distinguish their fellows at a distance, and they 
may be even protective when the animal is at rest among 
herbage — the only time when it would need protective colour- 
ing. Until the habits of the zebra have been observed with 
special reference to these points, it is surely somewhat hasty 
to declare that the stripes "cannot afford any protection."^ 

Colcmr proportionate to Integumenta/ry Development 

The wonderful display and endless variety of colour in 
which butterflies and birds so far exceed all other animals, 
seems primarily due to the excessive development and endless 
variations of the integumentary structures of these two 
groups. No insects have such widely expanded wings in pro- 
portion to their bodies as butterflies and moths ; in none do 
the wings vary so much in size and form, and in none are they 
clothed with such a beautiful and highly-organised coating of 
scales. According to the general principles of the production 
of colour already explained, these long continued expansions of 
membranes and developments of surface-structures must have 
led to numerous colour-changes, which have been sometimes 
checked, sometimes fixed and utilised, sometimes intensified, 

' For further information on this point, see Darwinism, p. 220. 



V COLOURS OF ANIMALS 369 

by natural selection, according to the needs of the animal. 
In birds, too, we have the wonderful clothing of plumage — 
the most highly organised, the most varied, and the most 
expanded of all dermal appendages. The endless processes of 
growth and change during the development of feathers, and 
the enormous extent of this delicately-organised surface, must 
have been highly favourable to the production of varied 
colour-effects, which, when not injurious, have been merely 
fixed for purposes of specific identification, but have often 
been modified or suppressed whenever different tints were 
needed for purposes of protection. 

Selection by Females not a cause of Colour 

To conscious sexual selection — that is, the actual choice by 
the females of the more brilliantly -coloiu-ed males or the 
rejection of those less gaily coloured — I believe very little if 
any efiect is directly due. It is undoubtedly proved that in 
birds the females do sometimes exert a choice; but the 
evidence of this fact, collected by Mr. Darwin {Descent of Man, 
chap, xiv.), does not prove that colour determines that choice, 
while much of the strongest evidence is directly opposed to 
this view. All the facts appear to be consistent with the 
choice depending on a variety of male characteristics, with 
some of which colour is often correlated. Thus it is the 
opinion of some of the best observers that vigour and liveli- 
ness are most attractive, and these are no doubt usually 
associated with intensity of colour. Again, the display of the 
various ornamental appendages of the male during courtship 
may be attractive ; but these appendages, with their bright 
colours or shaded patterns, are due probalsly to general laws 
of growth, and to that superabundant vitality which we have 
seen to be a cause of colour. But there are many considera- 
tions which seem to show that the possession of these orna- 
mental appendages and bright colours in the male is not an 
important character functionally, and that it has not been 
produced by the action of conscious sexual selection. Amid 
the copious mass of facts and opinions collected by Mr. 
Darwin as to the display of colour and ornaments by the male 
birds,, there is a total absence of any evidence that the females, 
as a rule, admire or even notice this display. The hen, the 

2b 



m TROPICAL NATURE 



turkey, and the pea-fowl go on feeding while the male is dis- 
playing his finery ; and there is reason to believe that it is 
his persistency and energy rather than his beauty which 
wins the day. Again, evidence collected by Mr. Darwin 
himself, proves that each bird finds a mate under any 
circumstances. He gives a number of cases of one of a 
pair of birds being shot, and the survivor being always 
found paired again almost immediately. This is sufficiently 
explained on the assumption that the destruction of birds by 
various causes is continually leaving widows and widowers in 
nearly equal proportions, and thus each one finds a fresh 
mate ; and it leads to the conclusion that permanently 
unpaired birds are very scarce, so that, speaking broadly, 
every bird finds a mate and breeds. But this would almost 
or quite neutralise any effect of sexual selection of colour or 
ornament, since the less highly-coloured birds would be at 
little or no disadvantage as regards leaving healthy offspring. 
If, however, heightened colour is correlated with health and 
vigour ; and if these healthy and vigorous birds provide best 
for their young, and leave offspring which, being equally 
healthy and vigorous, can best provide for themselves — which 
cannot be denied — then natural selection becomes a preserver 
and intensifier of colour. 

Another most important consideration is, that male butter- 
flies rival or even excel the most gorgeous male birds in 
bright colours and elegant patterns ; and among these there is 
literally not one particle of evidence that the female is influ- 
enced by colour, or even that she has any power of choice, 
while there is much direct evidence to the contrary {Descent 
of Mem, p. 3 1 8). The weakness of the evidence for conscious 
sexual selection among these insects is so palpable that Mr. 
Darwin is obliged to supplement it by the singularly incon- 
clusive argument that, " Unless the female prefer one male to 
another, the pairing must be left to mere chance, and this 
does not appear probable" (I.e. p. 317). But he has just 
said : " The males sometimes fight together in rivalry, and 
many may be seen pursuing or crowding round the same 
female;" while in the case of the silk-moths, "the females 
appear not to evince the least choice in regard to their j)art- 
ners." Surely the plain inference from all this is, that males 



V COLOURS OF ANIMALS 371 

jSght and struggle for the almost passive female, and that the 
most vigorous and energetic, the strongest-winged or the most 
persevering, wins her. How can there be chance in this ? 
Natural selection would here act, as in birds, in perpetuating 
the strongest and most vigorous males ; and as these would 
usually be the more highly coloured of their race, the same 
results would be produced as regards the intensification and 
variation of colour in the one case as in the other. 

Let us now see how these principles will apply to some of 
the cases adduced by Mr. Darwin in support of his theory of 
conscious sexual selection. 

In Descent of Man, 2d ed., pp. 307-316, we find an elaborate 
account of the various modes of colouring of butterflies and 
moths, proving that the coloured parts are always more or 
less displayed, and that they have some evident relation to 
an observer. Mr. Darwin then says : " From the several 
foregoing facts it is impossible to admit that the brilliant 
colours of butterflies, and of some few moths, have commonly 
been acquired for the sake of protection. We have seen that 
their colours and elegant patterns are arranged and exhibited 
as if for display. Hence I am led to believe that the females 
prefer or are most excited by the more brilliant males ; for on 
any other supposition the males woidd, as far as we can see, 
be ornamented to no purpose" {I.e. p. 316). I am not aware 
that any one has ever maintained that the brilliant colours of 
butterflies have " commonly been acquired for the sake of 
protection," yet Mr. Darwin has himself referred to cases in 
which the briUiant colour is so placed as to serve for protec- 
tion; as, for example, the eye-spots on the hind wings of 
moths, which are pierced by birds and so save the vital parts 
of the insect, while the bright patch on the orange-tip butter- 
flies, which Mr. Darwin denies are protective, may serve the 
same purpose. It is, in fact, somewhat remarkable how very 
generally the black spots, ocelli, or bright patches of colour 
are on the tips, margins, or discs of the wings ; and as the 
insects are necessarily visible while flying, and this is the 
time when they are most subject to attacks by insectivorous 
birds, the position of the more conspicuous parts at some 
distance from the body may be a real protection to them. 
Again, Mr. Darwin admits that the white colour of the male 



372 TROPICAL NATURE 



ghost-moth may render it more easily seen by the female 
■while flying about in the dusk ; and if to this we add that it 
will be also more readily distinguished from allied species, we 
have a reason for diverse ornamentation in these insects quite 
suflSicient to account for most of the facts, without believing 
in the selection of brilliant males by the females, for which 
there is not a particle of evidence. ^ 

Probable use of the Horns of Beetles 

A somewhat analogous case is furnished by the immense 
horns of some beetles of the families Copridse and Dynastidse, 
which Mr. Darwin admits are not used for fighting, and there- 
fore concludes are ornaments, developed through selection of 
the larger-horned males by the females. But it has been 
overlooked that these horns may be protective. The males 
probably fly about most, as is usually the case w:ith male 
insects ; and as they generally fly at dusk they are subject to 
the attacks of large-mouthed goatsuckers and podargi, as well 
as of insect -eating owls. Now the long, pointed, or forked 
horns, often divergent, or movable with the head, would 
render it very difficult for these birds to swallow such insects, 
and would therefore be an efficient protection, just as are the 
hooked spines of some stingless ants and the excessively hard 
integuments of many beetles, against the smaller insectivorous 
birds. 

GoAise of the greater Brilliomcy of some Female Insects 

The facts given by Mr. Darwin to show that butterflies 
and other insects can distinguish colours and are attracted by 
colours similar to their own, are quite consistent with the 
view that colour, which continually tends to appear, is utilised 
for purposes of identification and distinction when not required 
to be modified or suppressed for the purpose of protection. 
The cases of the females of some species of Thecla, Callidryas, 
Colias, and Hipparchia, which have more conspicuous mark- 
ings than the male, may be due to several causes : to obtain 
greater distinction from other species; for protection from 
birds, as in the' case of the yellow-underwing moths ; while 
sometimes — as in Hipparchia — the lower intensity of colour- 

' See M. Fabre'a testimony oe this point, Descent of Man, p. 291. 



V COLOURS OF ANIMALS 378 

ing in the female may lead to more contrasted markings. 
Mr. Darwin thinks that here the males have selected 
the more beautiful females; although one chief fact in 
support of his theory of conscious sexual selection is, that 
throughout the whole animal kingdom the males are usually 
so ardent that they will accept any female, while the females 
are coy and choose the handsomest males, whence it is 
believed the general brilliancy of males as compared with 
females has arisen. 

Perhaps the most curious cases of sexual difference of 
colour are those in which the female is very much more gaUy 
coloured than the male. This occurs most strikingly in some 
species of Pieris in South America, and of Diadema in the 
Malay islands ; and in both cases the females resemble species 
of the uneatable Danaidae and Heliconidse, and thus gain a 
protection. In the case of Pieris pyrrha, P. malenka, and P. 
lorena, the males are plain white and black, while the females 
are orange, yellow, and black, and so banded and spotted as 
exactly to resemble species of Heliconidse. Mr. Darwin 
admits that these bright colours have been acquired for 
protection ; but as- there is no apparent cause for the strict 
limitation of the colour to the female, he believes that it has 
been kept down in the male by its being unattractive to her. 
This appears to me to be a supposition opposed to the whole 
theory of sexual selection itself. For this theory is, that 
minute variations of colour in the male are attractive to the 
female, have always been selected, and that thus the brilliant 
male colours have been produced. But in this case he thinks 
that the female butterfly had a constant aversion to every 
trace of colour, even when we must suppose it was constantly 
recurring during the successive variations which resulted in 
such a marvellous change in herself. But the case admits of 
a much more simple interpretation. For if we consider the 
fact that the females frequent the forests where the Heli- 
conidse abound, while the males fly much in the open and 
assemble in great numbers with other white and yellow 
butterflies on the banks of rivers, may it not be possible 
that the appearance of orange stripes or patches would be as 
injurious to the male as it is useful to the female, by making 
him a more easy mark for insectivorous birds among his 



374 TROPICAL NATURE 



white companions ? This seems a more probable supposition 
than the altogether hypothetical choice of the female, some- 
times exercised in favour of and sometimes against every new 
variety of colour in her partner. 

A strictly analogous case is that of the glow-worm, whose 
light, as originally suggested by Mr. Belt, is admitted to 
be a warning of its uneatability to insectivorous nocturnal 
animals. The male, having wings, does not require this 
protection. In the tropics the number of nocturnal insect- 
ivorous birds and bats is very much greater, hence winged 
species possess the Ught, as they would otherwise be eaten by 
mistake for more savoury insects; and it may be that the 
luminous Elateridse of the tropics really mimic the true fire- 
flies (Lampyridse), which are uneatable. This is the more 
probable, as the Elateridse, in the great majority of species, 
have brown or protective colours, and are therefore certainly 
palatable to insectivorous animals. 

Origin of the Ornamental Plwnmge of Male Birds 

We now come to such wonderful developments of plum- 
age and colour as are exhibited by the peacock and the 
Argus-pheasant; and I may here mention that it was the case 
of the latter bird, as fully discussed by Mr. Darwin, which 
first shook my belief in " sexual," or more properly " female " 
selection. The long series of gradations by which the beauti- 
fully shaded ocelli on the secondary wing-feathers of this bird 
have been produced, are clearly traced out, the result being a 
set of markings so exquisitely shaded as to represent " balls 
lying loose within sockets " — ^purely artificial objects of which 
these birds could have no possible experience. That this 
result should have been attained, through thousands and tens 
of thousands of female birds aU preferring those males whose 
markings varied slightly in this one direction, this uniformity 
of choice continuing through thousands and tens of thousands 
of generations, is to me absolutely incredible. And when, 
further, we remember that those which did not so vary 
would also, according to all the evidence, find mates and leave 
ofispring, the actual result seems quite impossible of attain- 
ment by such means. 



V COLOURS OF ANIMALS 375 

Without pretending to solve completely so difficult a 
problem as that of the origin and uses of the variously 
coloured plumes and ornaments so often possessed by male 
birds, I would point out a few facts which seem to afford a 
clue. And first, the most highly-coloured and most richly- 
varied markings occur on those parts of the plumage which 
have undergone the greatest modification, or have acquired 
the most abnormal development. In the peacock, the tail- 
coverts are enormously developed, and the "eyes" are 
situated on the greatly dilated ends of these elongated 
feathers. In the birds-of-paradise, breast, or neck, or head, 
or taU-feathers, are greatly developed and highly coloured. 
The hackles of the cock and the scaly breasts of humming- 
birds are similar developments ; while in the Argus-pheasant 
the secondary quills are so enormously lengthened and 
broadened as to have become almost useless for flight. Now 
it is easily conceivable that during this process of develop- 
ment inequalities in the distribution of colour may have 
arisen in different parts of the same feather, and that spots 
and bands may thus have become broadened out into shaded 
spots or ocelli, in the way indicated by Mr. Darwin, much 
as the spots and rings on a soap-bubble increase with increas- 
ing tenuity. This is the more probable, because in domestic 
fowls varieties of colour tend to become symmetrical, quite 
independently of sexual selection (Descent of Man, p. 424). 
This is one of those crucial facts which, on Mr. Darwin's 
theory, ought not to happen, and which plainly indicate that 
symmetrical markings arise from the action of some general 
laws of colour-development. 

If now we accept the evidence of Mr. Darwin's most 
trustworthy correspondents, that the choice of the female, so 
far as she exerts any, falls upon the " most vigorous, defiant, 
and mettlesome male ; " and if we further believe, what is 
certainly the case, that these are as a rule the most brightly 
coloured and adorned with the finest developments of plum- 
age — we have a real and not a hypothetical cause at work. 
For these most healthy, vigorous, and beautiful males will 
have the choice of the finest and most healthy females, will 
have the most numerous and healthy families, and will be 
able best to protect and rear those families. Natural selec- 



376 TROPICAL NATURE 



tion, and what may be termed male selection, will tend to 
give them the advantage in the struggle for existence, and 
thus the fullest plumage and the finest colours will be trans- 
mitted, and tend to advance in each succeeding generation. 

Theory of Display of Ornaments hy Males 

The full and interesting account given by Mr. Darwin of 
the colours and habits of male and female birds {Descent of 
Man, chaps, xiii. and xiv.), proves that in most, if not in 
all cases, the male birds fully display their ornamental plum- 
age before the females or in rivalry with each other ; but on 
the essential point of whether the female's choice is deter- 
mined by minute dififerences in these ornaments or in their 
colours, there appears to be an entire absence of evidence. 
In the section on "Preference for particular Males by the 
Females," the facts quoted show indifference to colour, except 
that some colour similar to their own seems to be preferred. 
But in the case of the hen canary who chose a greenfinch in 
preference to either chaflSnch or goldfinch, gay colours had 
evidently no preponderating attraction. There is some evi- 
dence adduced that female birds may, and probably do, 
choose their mates, but none whatever that the choice is 
determined by difference of colour ; and no less than three 
eminent breeders informed Mr. Darwin that they " did not 
believe that the females prefer certain males on account of 
the beauty of their plumage." Again, Mr. Darwin himself 
says : " As a general rule colour appears to have little influ- 
ence on the pairing of pigeons." The oft-quoted case of Sir 
R. Heron's pea-hens, which preferred an " old pied cock " to 
those normally coloured, is a very unfortunate one, because 
pied birds are just those that are not favoured in a state of 
nature, or the breeds of wild animals would become as varied 
and mottled as our domestic varieties. If such irregular 
fancies were not rare exceptions, the. production of definite 
colours and patterns by the choice of the female birds, or in 
any other way, would be impossible. 

There remains, however, to be accounted for, the remark- 
able fact of the display by the male of each species of its 
peculiar beauties of plumage and colour — a display which Mr. 



V COLOURS OF ANIMALS 377 

Darwin evidently considers to be the strongest argument in 
favour of conscious selection by the female. This display is, 
no doubt, a very interesting and important phenomenon ; but 
it may, I believe, be satisfactorily explained on the general 
principles here laid down, without calling to our aid a purely 
hypothetical choice exerted by the female bird. 

At pairing-time the male is in a state of excitement, and 
full of exuberant energy. Even unornamental birds flutter 
their wings or spread them out, erect their tails or crests, 
and thus give vent to the nervous excitability with which 
they are overcharged. It is not improbable that crests and 
other erectile feathers may be primarily of use in frightening 
away enemies, since they are generally erected when angry 
or during combat. Those individuals who were most pug- 
nacious and defiant, and who brought these erectile plumes 
most frequently and most powerfully into action, would 
tend to leave them further developed in some of their 
descendants. If, in the course of this development, colour 
appeared — and we have already shown that such develop- 
ments of plumage are a very probable cause of colour — 
we have every reason to believe it would be most vivid in 
these most pugnacious and energetic individuals ; and as 
these would always have the advantage in the rivalry 
for mates (to which advantage the excess of colour and 
plumage might sometimes conduce), there seems nothing to 
prevent a progressive development of these ornaments in all 
dominant races ; that is, wherever there was such a surplus of 
vitality, and such complete adaptation to conditions, that the 
inconvenience or danger produced by such ornaments was so 
comparatively small as not to affect the superiority of the 
race over its nearest allies. 

But if those portions of the plumage which were originally 
erected under the influence of anger or fear became largely 
developed and brightly coloured, the actual display under 
the influence of jealousy or sexual excitement becomes quite 
intelligible. The males, in their rivalry with each other, 
would endeavour to excel their enemies as far as voluntary 
exertion would enable them to do so, just as they endeavour 
to rival each other in song, even sometimes to the point of 
causing their own destruction. 



378 TROPICAL NATURE 



Natural Selection as neutralising Sexual Selection 

There is also a general argument against Mr. Darwin's 
views on this question, founded on the nature and potency 
of " natural " as opposed to " sexual " selection, which appears 
to me to be of itself almost conclusive as to the whole matter 
at issue. Natural selection, or the survival of the fittest, 
acts perpetually and on an enormous scale. Taking the ofi- 
spring of each pair of birds as, on the average, only six 
annually, one-third of these at most will be preserved, while 
the two-thirds which are least fitted will die. At intervals of 
a few years, whenever unfavourable conditions occur, five- 
sixths, nine-tenths, or even a greater proportion of the whole 
yearly production are weeded out, leaving only the most 
perfect and best adapted to survive. Now unless these sur- 
vivors are, on the whole, the most ornamental, this rigid 
natural selection must neutralise and destroy any influence 
that may be exerted by female selection. The utmost that 
can be claimed for the latter is, that a small fraction of the 
least ornamented do not obtain mates, while a few of the 
most ornamented may leave more than the average number of 
offspring. Unless, therefore, there is the strictest correlation 
between ornament and general perfection, the more brightly 
coloured or ornamented varieties can obtain no permanent 
advantage ; and if there is (as I maintain) such a correlation, 
then the sexual selection of colour or ornament, for which 
there is little or no evidence, becomes needless, because 
natural selection, which is an admitted vera causa, will itself 
produce all the results. 

In the case of butterflies the argument becomes even 
stronger, because the fertility is so much greater than in 
birds, and the weeding-out of the unfit takes place, to a great 
extent, in the egg and larva state. Unless the eggs and 
larvae which escaped to produce the next generation were 
those which would produce the more highly-coloured butter- 
flies, it is difficult to perceive how the slight preponderance 
ol colour sometimes selected by the females should not be 
wholly neutralised by the extremely rigid selection for other 
qualities to which the offspring in every stage are exposed. 
The only way in which we can account for the observed facts 



V COLOURS OF ANIMALS 379 

is, by the supposition that colour and ornament are strictly 
correlated with health, vigour, and general fitness to survive. 
We have shown that there is reason to believe that this is 
the case, and if so, conscious sexual selection becomes as 
unnecessary as it would certainly be ineffective. 

Greater Brilliancy of some Female Birds 

There is one other very curious case of sexual colouring 
among birds — that, namely, in which the female is decidedly 
brighter or more strongly marked than the male, as in the 
fighting quails (Turnix), painted snipe (Ehynchsea), two 
species of phalarope (Phalaropus), and the common cassowary 
(Casuarius galeatus). In all these cases it is known that the 
males take charge of and incubate the eggs, while the females 
are almost always larger and more pugnacious. 

In my "Theory of Birds' Nests" (see p. 132) I imputed 
this difference of colour to the greater need for protection by 
the male bird while incubating, to which Mr. Darwin has 
objected that the difference is not sufficient, and is not always 
so distributed as to be most effective for this purpose ; and he 
believes that it is due to reversed sexual selection — that is, to 
the female taking the usual rdle of the male, and being chosen 
for her brighter tints. "We have already seen reason for 
rejecting this latter theory in every case ; and I also admit 
that Mr. Darwin's criticism is sound, and that my theory of 
protection is, in this case, only partially, if at all, applicable. 
But the theory now advanced, of intensity of colour being 
due to general vital energy, is quite applicable ; and the fact 
that the superiority of the female in this respect is quite 
exceptional, and is therefore probably not in any case of very 
ancient date, will account for the difference of colour thus 
produced being always very slight. 

Colowr-cleiBBlopment as illustrated by Humming-birds 

Of the mode of action of the general principles of colour- 
development among animals, we have an excellent examplfi in 
the humming-birds. Of all birds these are at once the 
smallest, the most active, and the fullest of vital energy. 
When poised in the air their wings are invisible owing to 
the rapidity of their motion, and when startled they dart 



380 TROPICAL NATURE 



away with the rapidity of a flash of light. Such active 
creatures would not be an easy prey to any rapacious bird ; 
and if one at length was captured, the morsel obtained would 
hardly repay the labour. We may be sure, therefore, that 
they are practically unmolested. The immense variety they 
exhibit in structure, plumage, and colour, indicates a high 
antiquity for the race; while their general abundance in 
individuals shows that they are a dominant group, well 
adapted to all the conditions of their existence. Here we 
find everything necessary for the development of accessory 
plumes and colour. The surplus vital energy shown in their 
combats and excessive activity has expended itself in ever- 
increasing developments of plumage, and greater and greater 
intensity of colour, regulated only by the need for specific 
identification which would be especially required in such 
small and mobile creatures. Thus may be explained those 
remarkable difierences of colour between closely-allied species, 
one having a crest like the topaz, while in another it resembles 
the sapphire. The more vivid colours and more developed 
plumage of the males, I am now inclined to think, may be 
almost wholly due to their greater vital energy, and to those 
general laws which lead to such superior developments even 
in domestic breeds ; but in some cases the need of protection 
by the female whUe incubating, to which I formerly imputed 
the whole phenomenon, may have suppressed a portion of the 
ornament which she would otherwise have attained. 

The extreme pugnacity of humming-birds has been noticed 
by all observers, and it seems to be to some extent propor- 
tioned to the degree of colour and ornament in the species. 
Thus Mr. Salvin observes of Eugenes fulgens, that it is " a most 
pugnacious bird," and that " hardly any species shows itself 
more brilliantly on the wing." Again of Campylopterus 
hemileucurus : " the pugnacity of this species is remarkable. 
It is very seldom that two males meet without an aerial 
battle ; " and " the large and showy tail of this humming-bird 
makes it one of the most conspicuous on the wing." Again, 
the elegant frill-necked Lophornis ornatus "is very pug- 
nacious, erecting its crest, throwing out ■ its whiskers, and 
attacking every humming-bird that may pass within its range 
of vision ; " and of another species, L. magnificus, it is said 



V COLOURS OF ANIMALS 381 

that " it is so bold that the sight of man creates no alarm." 
The beautifully-coloured Thaumastura cora "rarely permits 
any other humming-bird to remain in its neighbourhood, but 
wages a continual and terrible war upon them." The magni- 
ficent bar-tail, Cometes sparganurus, one of the most imposing 
of all the humming-birds, is extremely fierce and pugnacious, 
" the males chasing each other through the air with surprising 
perseverance and acrimony." These are all the species I find 
noticed as being especially pugnacious, and every one of them 
is exceptionally coloured or ornamented, while not one of 
the small, plain, and less ornamental species are so described, 
although many of them are common and well observed species. 
It is also to be noticed that the remarkable pugnacity of these 
birds is not confined to one season or even to birds of the 
same species, as is usual in sexual combats, but extends to any 
other species that may be encountered, while they are said 
even to attack birds of prey that approach too closely to 
their nests. It must be admitted that these facts agree well 
with the theory that colour and ornament are due to surplus 
vital energy and a long course of unchecked development. 
We have also direct evidence that the males are more active 
and energetic than the females. Mr. Gosse says that the 
whirring made by the male Polytmus humming-bird is shriller 
than that produced by the female ; and he also informs us 
that the male flies higher and frequents mountains, while the 
female keeps to the lowlands. ^ 

Theory of Normal Golowrs 

The remaining kinds of animal colours, those which can 
neither be classed as protective, warning, nor sexual, are for 
the most part readily explained on the general principles of 
the development of colour which we have now laid down. It 
is a most suggestive fact that in cases where colour is required 
only as a warning, as among the uneatable caterpillars, we 
find, not one or two glaring tints only, but every kind of 
colour disposed in elegant patterns, and exhibiting almost as 
much variety and beauty as among insects and birds. Yet 

' Some other oases are noticed at p. 317. For some further develop- 
ments and illustrations of the theory of sexual colour, see Darwinism, 
chap. X. 



382 TROPICAL NATURE 



here, not only is sexual selection out of the question, but 
the need for recognition and identification by others of the 
same species seems equally unnecessary. We can then only 
impute this variety to the normal production of colour in 
organic forms when fully exposed to light and air and under- 
going great and rapid developmental modification. Among 
more perfect animals, where the need for recognition has been 
added, we find intensity and variety of colour at its highest 
pitch among the South American butterflies of the families 
Heliconidse and Danaidse, as well as among the Nymphalidse 
and Erycinidse, many of which obtain the necessary protection 
in other ways. Among birds also, wherever the habits are 
such that no special protection is needed for the females, and 
where the species frequent the depths of tropical forests, and 
are thus naturally protected from the swoop of birds of prey, 
we find almost equally intense coloration, as in the trogons, 
barbets, and gapers. 

Local Causes of Colour-development 

Another real, though as yet inexplicable cause of diversity 
of colour is to be found in the influence of locality. It is 
observed that species of totally distinct groups are coloured 
alike in one district, while in another district the allied 
species all undergo the same change of colour. Cases of this 
kind have been adduced by Mr. Bates, by Mr. Darwin, and 
by myself, and I will here give the more curious and important 
examples which I have been able to collect.^ 

The Influence of Locality on Colour in Butterflies and Birds 
Our first example is from tropical Africa, where we find 
two unrelated gi-oups of butterflies belonging to two very 
distinct families(Nymphalid8e and Papilionidse) characterised by 
a prevailing blue-green colour not found in any other continent.^ 
Again, we have a group of African Pieridse which are white 
or pale yellow with a marginal row of bead-like black spots ; 
and in the same country one of the Lycsenidae (Leptena 

^ These were first given in my Address to the Biological Section of the 
British Association at Glasgow in 1876. 

^ Eomaleosoma and Euryphene (Nymphalidse), Papilio zalmoxis and 
several species of the Nireus-group (Papilionidse). 



V COLOURS OP ANIMALS 383 

erastus) is coloured so exactly like these that it was at first 
described as a species of Pieris. None of these four groups 
are known to be in any way specially protected, so that the 
resemblance cannot be due to protective mimicry. 

In South America we have far more striking cases, for in 
the three subfamilies Danainae, Acrseinse, and Heliconiinse, all 
of which are specially protected, we find identical tints and 
patterns reproduced, often in the greatest detail, each peculiar 
type of coloration being characteristic of distinct geographical 
subdivisions of the continent. Nine very distinct genera are 
implicated in these parallel changes — Lycorea, Ceratinia, 
Mechanitis, Ithomia, Melinaea, Tithorea, Acraea, Heliconius, 
and Eueides, groups of three or four (or even five) of thein 
appearing together in the same livery in one district, while 
in an adjoining district most or all of them undergo a simul- 
taneous change of coloration or of marking. Thus in the 
genera Ithomia, Mechanitis, and Heliconius, we have species 
with yellow apical spots in Guiana, aU. represented by allied 
species with white apical spots in South Brazil. In Mechan- 
itis, Melinsea, and Heliconius, and sometimes in Tithorea, the 
species of the Southern Andes (Bolivia and Peru) are char- 
acterised by an orange and black livery, while those of the 
Northern Andes (New Granada) are almost always orange- 
yellow and black. Other changes of a like nature, which it 
would be tedious to enumerate, but which are very striking 
when specimens are examined, occur in species of the same 
groups inhabiting these same localities, as well as Central 
America and the Antilles. The resemblance thus produced 
between widely different insects is sometimes general, but 
often so close and minute that only a critical examination of 
structiu-e can detect the difference between them. Yet all 
are alike protected by the nauseous secretion which renders 
them unpalatable to birds. ^ 

In another series of genera (Gatagramma, Callithea, and 
Agrias), all belonging to the Nymphalidse, we have the most 
vivid blue ground, with broad bands of orange, crimson, or a 
different tint of blue or purple, exactly reproduced in corre- 
sponding, yet unrelated species, occurring in the same locality ; 

^ The atove cases have now been satisfactorily explained as a modified 
form of mimicry. See Darwinism., pp. 249-257. 



TROPICAL NATURE 



yet, as none of these groups are known to be specially pro- 
tected, this can hardly be true mimicry. A few species of 
two other genera in the same country (Eunica and Siderone) 
also reproduce the same colours, but with only a general 
resemblance in the markings. Yet again, in tropical America 
we have species of Apatura which, sometimes in both sexes, 
sometimes in the female only, exactly imitate the peculiar 
markings of another genus (Heterochroa) confined to America ; 
here, again, neither genus is protected, and the similarity 
must be due to unknown local causes. 

But it is among islands that we find some of the most 
striking examples of the influence of locality on colour, 
generally in the direction of paler, but sometimes of darker 
and more brilliant hues, and often accompanied by an unusual 
increase of size. Thus in the Moluccas and New Guinea we 
have several Papilios (P. euchenor, P. ormenus, and P. tydeus) 
distinguished from their allies by a much paler colour, espe- 
cially in the females, which are almost white. Many species 
of Danais (forming the subgenus Ideopsis) are also very pale. 
But the most curious are the Euploeas, which in the larger 
islands are usually of rich dark colours, while in the small 
islands of Banda, K6, and Matabello at least three species not 
nearly related to each other (E. hoppferi, E. euripon, and E. 
assimilata) are all broadly banded or sufiused with white, 
their allies in the larger islands being in each case very much 
darker. Again, in the genus Diadema, belonging to a dis- 
tinct family, three species from the small Aru and K6 islands 
(D. deois, D. hewitsonii, and D. polymena) are all more 
conspicuously white-marked than their representatives in the 
larger islands. In the beautiful genus Cethosia, a species 
from the small island of Waigiou (C. cyrene) is the whitest of 
the genus. Prothoe is represented by a blue species in the 
continental island of Java, while those inhabiting the ancient 
insular groups of the Moluccas and New Guinea are all pale 
yeUow or white. The genus Drusilla, almost confined to these 
islands, comprises many species which are all very pale; 
while in the small island of Waigiou is found a very distinct 
genus, Hyantis, which, though differing completely in the 
neuration of the wings, has exactly the same pale colours and 
large ocellated spots as Drusilla. 



V COLOURS OF ANIMALS 385 

Equally remarkable is the increase of size in some islands. 
The small island of Amboina produces larger butterflies than 
any of the much larger islands which surround it. This is 
the case with at least a dozen butterflies belonging to many 
distinct genera/ so that it is impossible to attribute the fact 
to other than some local influence. In Celebes, as I have 
elsewhere pointed out,^ we have a peculiar form of wing and 
much larger size running through a whole series of distinct 
butterflies ; and this seems to take the place of any speciality 
in colour. 

In a very small collection of insects recently brought from 
Duke-of-York island (situated between New Britain and New 
Ireland) are several of remarkably white or pale coloration. 
A species of Euplaea is the whitest of all known species of 
that extensive genus ; while a beautiful diurnal moth is much 
whiter than its ally in the larger island of New Guinea. 
There is also a magnificent longicorn beetle almost entirely 
of an ashy white colour, s 

From the Fiji islands we have comparatively few butter- 
flies ; but there are several species of Diadema of unusually 
pale colours, some almost white. 

The Philippine islands seem to have the peculiarity of 
developing metallic colours. "We find there at least three 
species of Euplsea* not closely related, and all of more 
intense metallic lustre than their allies in other islands. ' 
Here also we have one of the large yellow Ornithopterse 
(0. magellanus), whose hind wings glow with an intense 
opaline lustre not found in any other species of the entire 
group; and an AdoUas^ is larger and of more brilliant 
metallic colouring than any other species in the archipelago. 
In these islands also we find the extensive and wonderful 
genus of weevils (Pachyrhynchus), which in their brilliant 

^ Ornithoptera priamus, 0. helena, Papilio delphobus, P. ulysses, P. gam- 
brisius, P. codrus, Iphias leucippe, Euplsea prothoe, Hestia idea, Athyma 
jocaste, Diadema pandarus, Nymphalis pyrrhus, N. euryalus, Brasilia jairus. 

" Oontributions to the Theory of Natural Selection, pp. 168-173. 

' These insects are described and figured in the Proceedings of the Zoolo- 
gical Society for 1877, p. 139. Their names are Euplsea browni, Alcides 
aurora, and Batocera browni. 

•■ Euplssa hewitsonii, E. diocletiana, E. lietifica. 

^ Adolias calliphoms. 

3c 



386 TROPICAL NATURE 



metallic, colouring surpass anything found in the whole 
eastern hemisphere, if not in the whole world. 

In the Andaman islands, in the Bay of Bengal, there are a 
considerable number of peculiar species of butterflies differing 
slightly from those on the continent, and generally in the 
direction of paler or more conspicuous colouring. Thus two 
species of Papilio which on the continent have the tails black, 
in their Andaman representatives have them either red or 
white-tipped.^ Another species ^ is richly blue-banded where 
its allies are black ; while three species of distinct genera of 
Nymphalidse ^ all differ from their allies on the continent in 
being of excessively pale colours as well as of somewhat larger 
size. 

In Madagascar we have the very large and singularly 
white -spotted Papilio antenor, while species of three other 
genera* are very white or conspicuous as compared with 
their continental allies. 

Passing to the West Indian islands and Central America 
(which latter country has formed a group of islands in very 
recent times), we have similar indications. One of the largest 
of the Papilios inhabits Jamaica,^ while another, the largest 
of its group, is found in Mexico.^ Cuba has two of the same 
genus whose colours are of surpassing brilliancy ; ^ while the 
fine genus Clothilda — confined to the Antilles and Central 
America — is remarkable for its rich and showy colouring. 

Persons who are not acquainted with the important 
structural differences that distinguish these various genera 
of butterflies can hardly realise the importance and the 
significance of such facts as I have now detailed. It may 
be well, therefore, to illustrate them by supposing parallel 
cases to occur among the Mammalia. We might have, for 
example, in Africa, the gnus, the elands, and the buffaloes, 
all coloured and marked like zebras, stripe for stripe over 
the whole body exactly corresponding. So the hares, mar- 
mots, and squirrels of Europe might be all red with black 
feet, while the corresponding species of Central Asia were all 

^ Papilio rhodifer (near P. douWedayi), and Papilio chariolea (near P. 
memnon). 2 Papilio mayo. 

' Euplsea andamanensis, Cethosia biblis, Cyrestis codes. 
* Danais nossima, Melanitis massoura, Diadema dexithea. 
" Papilio homerus. ^ P. daunua. ' P. gundlachianus, P. Tillierai, 



V COLOURS OF ANIMALS 387 

yellow with black heads. In North America we might have 
raccoons, squirrels, and opossums, in parti-coloured livery of 
white and black, so as exactly to resemble the skunk of the 
same country ; while in South America they might be black 
with a yellow throat-patch, so as to resemble with equal 
closeness the tayra of the Brazilian forests. Were such 
resemblances to occur in anything like the number and with 
the wonderful accuracy of imitation met with among the 
Lepidoptera, they would certainly attract universal attention 
among naturalists, and would lead to the exhaustive study 
of the influence of local causes in producing such startling 
results. 

One somewhat similar case does indeed occur among the 
Mammalia, two singular African animals, the Aard-wolf (Pro- 
teles) and the hyaena-dog (Lycaon), both strikingly resembling 
hyaenas in their general form as well as in their spotted 
markings. Belonging as they all do to the Carnivora, though 
to three distinct families, it seems quite an analogous case 
to those we have imagined; but as the Aard-wolf and the 
hysena-dog are both weak animals compared with the hyaena, 
the resemblance may be useful, and in that case would come 
under the head of mimicry. This seems the more probable 
because, as a rule, the colours of the Mammalia are protective, 
and are too little varied to allow of the influence of local 
causes producing any well-marked efiects. 

When we come to birds, however, the case is different, 
for although they do not exhibit such distinct marks of the 
influence of locality as do butterflies — probably because the 
causes which determine colour are in their case more complex 
— yet there are distinct indications of some effect of the kind, 
and we must devote some little time to their consideration. 

One of the most curious cases is that of the parrots of the 
West Indian islands and Central America, several of which 
have white heads or foreheads, occurring in two distinct 
genera,^ while none of the more numerous parrots of South 
America are so coloured. In the small island of Dominica 
we have a very large and richly-coloured parrot (Chrysotis 
augusta) corresponding to the large and richly -coloured 
butterfly (PapUio homerus) of Jamaica. 
1 Pionus albifrons and Clhryaotis senilis (C. America), C!hrysotis salloei (Hayti). 



TROPICAL NATURE 



The Andaman islands are equally remarkable, at least six 
of tlie peculiar birds differing from their continental allies in 
being much lighter, and sometimes with a large quantity of 
pure white in the plumage, ■*■ exactly corresponding to what 
occurs among the butterflies. 

In the Philippines this is not so marked a feature ; yet we 
have here the only known white-breasted kingcrow (Dicrurus 
mirabilis); the newly discovered Eurylaemus steerii, wholly 
white beneath ; three species of Diceum, all white beneath ; 
several species of Parus, largely white-spotted ; while many of 
the pigeons have light ashy tints. The birds generally, how- 
ever, have rich dark colours, similar to those which prevail 
among the butterflies. 

In Celebes we have a swallow-shrike and a peculiar small 
crow allied to the jackdaw,^ whiter than any of their allies in 
the surrounding islands, but otherwise the colours of the birds 
call for no special remark. 

In Timor and Flores we have white-headed pigeons,* and 
a long-tailed flycatcher almost entirely white. * 

In Duke-of-York island, east of New Guinea, we find that 
the four new species figured in the Proceedings of the Zoological 
Society for 1877 are dl remarkable for the unusual quantity 
of white in their plumage. They consist of a fiycatcher, a 
diceum, a wood-swallow, and a ground-pigeon,^ all equalling 
if not surpassing their nearest allies in whiteness, although 
some of these, from the Philippines, Moluccas, and Celebes, 
are sufficiently remarkable in this respect. 

In the small Lord Howe's island we have the recently 
extinct white rail (Notornis alba), remarkably contrasting with 
its allies in the larger islands of New Zealand. 

We cannot, however, lay any stress on isolated examples 
of white colour, since these occur in most of the great con- 
tinents; but where we find a series of species of distinct 
genera all diff'ering from their continental allies in a whiter 
coloration, as in the Andaman islands, Duke-of-York island, 

"■ Kittacincla albiventris, Geociohla albigularis, Sturnia andamanensia, 
Hyloterpe grisola var., lanthaenas palumtoides, Osmotreron ohloroptera. 

^ Aitamus monaohus, Corvus advena. 

* Ptilopus cinctus, P. albocinctus. * TcMtrea affinis, var. 

" Monaroha verticalis, Diceum eximium, Artamus insignis, Phlogsenas 
johannae. 



COLOURS OF ANIMALS 



and the West Indies, and, among butterflies, in the smaller 
Moluccas, the Andamans, and Madagascar, we cannot avoid 
the conclusion that in these insular localities some general 
cause is at work. 

There are other cases, however, in which local influences 
seem to favour the production or preservation of intense 
crimson or a very dark coloration. Thus in the Moluccas 
and New G-uinea alone we have bright red parrots belonging 
to two distinct families,^ and which therefore most probably 
have been independently produced or preserved by some 
common cause. Here, too, and in Australia we have black 
parrots and pigeons ; ^ and it is a most curious and suggestive 
fact that in another insular sub-region — that of Madagascar 
and the Mascarene islands — these same colours reappear in 
the same two groups.* 

Sense-perceptkm influenced by Golow of the Integuments 

Some very curious physiological facts bearing upon the 
presence or absence of white colours in the higher animals 
have lately been adduced by Dr. Ogle.* It has been found 
that a coloured or dark pigment in the olfactory region of 
the nostrils is essential to perfect smell, and this pigment is 
rarely deficient except when the whole animal is pure white. 
In these cases the creature is almost without smell or taste. 
This, Dr. Ogle believes, explains the curious case of the pigs 
in Virginia adduced by Mr. Darwin, white pigs being killed 
by a poisonous root which does not afiect black pigs. Mr. 
Darwin imputed this to a constitutional difference accompany- 
ing the dark colour, which rendered what was poisonous to 
the white-coloured animals quite innocuous to the black. Dr. 
Ogle, however, observes that there is no proof that the black 
pigs eat the root, and he believes the more probable explana- 
tion to be that it is distasteful to them ; while the white pigs, 
being deficient in smell and taste, eat it and are killed. 
Analogous facts occur in several distinct families. White 
sheep are killed in the Tarentino by eating Hypericum cris- 

' Lorius, Eos (Triohoglossidse), Ecleotus (Palaeornithidse). 

2 Microglossus, Calyptorhynchus, Turacsena. 

' Coracopsis, Alectrsenas. 

* Medico-Chwwrgical Transactions, vol. liii. (1870). 



390 TROPICAL NATURE 



pum, while black sheep escape ; white rhinoceroses are said to 
perish from eating Euphorbia candelabrum ; and white horses 
are said to suffer from poisonous food where coloured ones 
escape. Now it is very improbable that a constitutional 
immunity from poisoning by so many distinct plants should, 
in the case of such widely different animals, be always corre- 
lated with the same difference of colour ; but the facts are 
readily understood if the senses of smeU and taste are 
dependent on the presence of a pigment which is deficient 
in wholly white animals. The explanation has, however, 
been carried a step further, by experiments showing that the 
absorption of odours by dead matter, such as clothing, is 
greatly affected by colour, black being the most powerful 
absorbent, then blue, red, yellow, and lastly white. We 
have here a physical cause for the sense-inferiority of totally 
white animals which may account for their rarity in nature, 
for few, if any, wild animals are wholly white. The head, 
the face, or at least the muzzle or the nose, are generally 
black ; the ears and eyes are also often black ; and there is 
reason to believe that dark pigment is essential to good 
hearing, as it certainly is to perfect vision. We can there- 
fore understand why white cats with blue eyes are so often 
deaf, a peculiarity we notice more readily than their deficiency 
of smeU or taste. 

If, then, the prevalence of white coloration is generally 
associated with some deficiency in the acuteness of the most 
important senses, this colour becomes doubly dangerous, for 
it not only renders its possessor more conspicuous to its 
enemies, but at the same time makes it less ready in detect- 
ing the presence of danger. Hence, perhaps, the reason why 
white appears more frequently in islands, where compe- 
tition is less severe and enemies less numerous and varied. 
Hence, also, a reason why aJbinoism, although freely occur- 
ring in captivity, never maintains itself in a wild state, 
while melanism does. The peculiarity of some islands 
in having all their inhabitants of dusky colours (as the 
Galapagos) may also perhaps be explained on the same 
principles, for poisonous fruits may there abound which 
weed out all white or light -coloured varieties owing to 
their deficiency of smell and taste. We can hardly believe. 



V COLOURS OF ANIMALS 391 

however, that this would apply to white-coloured butterflies ; 
and this may be a reason why the effect of an insular habitat 
is more marked in these insects than in birds or mammals.^ 

It is even possible that this relation of sense -acuteness 
with colour may have had some influence on the development 
of the higher human races. If light tints of the skin were 
generally accompanied by some deficiency in the senses of 
smell, hearing, and vision, the white could never compete 
with the darker races so long as man was in a very low or 
savage condition, and wholly dependent for existence on the 
acuteness of his senses. But as the mental faculties became 
more fully developed and more important to his welfare than 
mere sense-acuteness, the lighter tints of skin and hair and 
eyes would cease to be disadvantageous whenever they were 
accompanied by superior brain-power. Such variations would 
then be preserved; and thus may have arisen the Xantho- 
chroic race of mankind, in which we find a high development 
of intellect accompanied by a slight deficiency in the acuteness 
of the senses as compared with the darker forms. 

Summary on Colour-development in Animals 

Let us now sum up the conclusions at which we have 
arrived as to the various modes in which colour is produced 
or modified in the animal kingdom. 

The various causes of colour in the animal world are, 
molecular and chemical change of the substance of their 
integuments, or the action on it of heat, Ught, or moisture. 
It is also produced by interference of light in superposed 
transparent lameUse, or by excessively fine surface -strise. 
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 as 
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, 
females, or young, or to divert attack from a vital part, as in 

1 In Darwinism, pp. 229, 230, 1 have suggested an explanation of most of 
the facts of oolonr in islands as due to the lesser need of protection. 



392 TROPICAL NATURE 



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 modification, or where there is a surplus of 
vital energy, as in male animals generally, and more especially 
at the breeding season. 

Colours are also more or less influenced by a variety of 
causes, such as the nature of the food, the photographic or 
physiological action of light, and also by some unknown local 
action, probably dependent on chemical peculiarities in the soil 
or vegetation. 

These various causes have acted and reacted in a variety 
of ways, and have been modified by conditions dependent on 
age or on sex, on competition with new forms, or on geo- 
graphical or climatic changes. In so complex a subject, for 
which experiment and systematic inquiry have done so little, 
we cannot expect to explain every individual case, or solve 
every difiiculty ; but it is believed that all the great features of 
animal coloration and many of the details become explicable 
on the principles we have endeavoured to lay down. 

It will perhaps be considered presumptuous to put forth 
this sketch of the subject of colour in animals as a substitute 
for one of Mr. Darwin's most highly elaborated theories — 
that of voluntary or perceptive sexual selection ; yet I ven- 
ture to think that it is more in accordance with the whole of 
the facts, and with the theory of natural selection itself ; and 
I would ask such of my readers as may be sufficiently in- 
terested in the subject, to read again chapters xi. to xvi. of 
the Descent of Man, and consider the whole subject from the 
point of view here laid down. The explanation of almost all 
the ornaments and colours of birds and insects as having been 
produced by the perceptions and choice of the females, has, 
I believe, staggered many evolutionists, but has been pro- 
visionally accepted because it was the only theory that even 
attempted to explain the facts. It may perhaps be a relief 
to some of them, as it has been to myself, to find that the 
phenomena can be conceived as dependent on the general 
laws of development, and on the action of " natural selection," 
which theory will, I venture to think, be relieved from an 



V COLOURS OF ANIMALS 393 

abnormal excrescence and gain additional vitality by the 
adoption of the views here imperfectly set forth.^ 

Although we have arrived at the conclusion that tropical 
light and heat can in no sense be considered as the cause of 
colour, there remains to be explained the undoubted fact that 
all the more intense and gorgeous tints are manifested by the 
animal life of the tropics; while in some groups, such as 
butterflies and birds, there is a marked preponderance of 
highly-coloured species. This is probably due to a variety of 
causes, some of which we can indicate, while others remain 
to be discovered. The luxuriant vegetation of the tropics 
throughout the entire year affords so much concealment that 
colour may there be safely developed to a much greater 
extent than in climates where the trees are bare in winter, 
during which season the struggle for existence is most severe, 
and even the slightest disadvantage may prove fatal. Equally 
important, probably, has been the permanence of favourable 
conditions in the tropics, allowing certain groups to continue 
dominant for long periods, and thus to carry out in one 
unbroken line whatever developments of plumage or colomr 
may once have acquired an ascendency. Changes of climatal 
conditions, and pre-eminently the glacial epoch, probably led 
to the extinction of a host of highly-developed and finely- 
coloured insects and birds in temperate zones, just as we 
loiow that it led to the extinction of the larger and more 
powerful mammalia which formerly characterised the tem- 
perate zone in both hemispheres ; and this view is supported 
by the fact that it is amongst those groups only which are 
now exclusively tropical that all the more extraordinary 
developments of ornament and colour are found. The obscure 
local causes of colour to which we have referred wiU also 
have acted most efficiently in regions where the climatal 
condition remained constant, and where migration was unneces- 
sary ; while whatever direct efiect may be produced by light 
or heat wiU necessarily have acted more powerfully within 
the tropics. And lastly, all these causes have been in action 
over an actually greater area in tropical than in temperate 

^ These views have been restated and enforced by much fresh illustration 
and argument in Darwinism, chap. x. 



394 TROPICAL NATURE 



zones ; -wliile, estimated potentially, in proportion to their life- 
sustaining power, the lands which enjoy a practically tropical 
climate (extending as they do considerably beyond the geo- 
graphical tropics) are very much larger than the temperate 
regions of the earth. 

Combining the effects of all these various causes, we are 
quite able to understand the superiority of the tropical parts 
of the globe, not only in the abundance and variety of their 
forms of life, but also as regards the ornamental appendages 
and vivid coloration which these forms present. 



VI 



THE COLOURS OF PLANTS AND THE ORIGIN OF THE 
COLOUK-SENSE 

Source of Colouring Matter in Plants — Protective Coloration and Mimicry 
in Plants — Attractive Colours of Fruits — Protective Coloui's of 
Fruits — Attractive Colours of Flowers — Attractive Odours in Flowers 
— Attractive Grouping of Flowers — Why Alpine Flowers are so beauti- 
ful — "Why Allied Species of Flowers differ in size and beauty — Absence 
of Colour in "Wind-fertilised Flowers — The same Theory of Colour 
applicable to Animals and Plants — Relation of the Colours of Flowers 
and their Geographical Distribution — Recent Views as to Direct 
Action of Light on the Colours of Flowers and Fruits — On the Origin 
of the Colour-sense: Supposed increase of Colour-perception within 
the Historical Period — Concluding Remarks on the Colour-sense. 

Source of Colouring Matter in Plants 

The colouring of plants is neither so varied nor so complex 
as that of animals, and its explanation accordingly offers 
fewer difficulties. The colours of foliage are, comparatively, 
little varied, and can be traced in almost all cases to a special 
pigment termed chlorophyll, to which is due the general green 
colour of leaves ; but the recent investigations of Mr. Sorby 
and others have shown that chlorophyll is not a simple green 
pigment, but that it really consists of at least seven distinct 
substances, varying in colour from blue to yeUow and orange. 
These differ in their proportions in the chlorophyll of differ- 
ent plants ; they have different chemical reactions ; they are 
differently affected by light ; and they give distinct spectra. 
Mr. Sorby further states that scores of different colouring 
matters are found in the leaves and flowers of plants, to some 
of which appropriate names have been given, as erythrophyll, 
which is red ; and phaiophyll, which is brown ; and many of 



396 TROPICAL NATURE 



these diifer greatly from each, other in their chemical com- 
position. These inquiries are at present in their infancy, but 
as the original term chlorophyll seems scarcely applicable 
under the present aspect of the subject, it would perhaps 
be better to introduce the analogous word chromophyll as 
a general term for the colouring matters of the vegetable 
kingdom. 

Light has a much more decided action on plants than 
on animals. The green colour of leaves is almost whoUy 
dependent on it; and although some flowers will become 
fully coloured in the dark, others are decidedly affected by 
the absence of light, even when the foliage is fully exposed to 
it. Looking therefore at the numerous colouring matters 
which are developed in the tissues of plants, the sensitiveness 
of these pigments to light, the changes they undergo during 
growth and development, and the facility with which new 
chemical combinations are effected by the physiological pro- 
cesses of plants as shown by the endless variety in the 
chemical constitution of vegetable products, we have no 
difficulty in comprehending the general causes which aid in 
producing the colours of the vegetable world, or the extreme 
variability of those colours. We may therefore here confine 
ourselves to an inquiry into the various uses of colour in the 
economy of plants, and this will generally enable us to under- 
stand how it has become fixed and specialised in the several 
genera and species of the vegetable kingdom. 

Protective Coloration and Mimicry in Plants 

In animals, as we have seen, colour is greatly influenced 
by the need of protection from, or of warning to, their 
numerous enemies, and by the necessity for identification 
and easy recognition. Plants rarely need to be concealed, 
and obtain protection either by their spines, their hardness, 
their hairy covering, or their poisonous secretions. A very 
few cases of what seem to be true protective colouring do, 
however, exist, the most remarkable being that of the " stone 
mesembryanthemum " of the Cape of Good Hope, which, in 
form and coloiu-, closely resembles the stones among which it 
grows; and Dr. Burchell, who first discovered it, believes 
that the juicy little plant thus generally escapes the notice 



VI COLOURS OF PLANTS 397 

of cattle and wild herbivorous animals. Mr. J. P. Mansel 
Weale also noticed that many plants growing in the stony 
Karoo have their tuberous roots above the soil, and these so 
perfectly resemble the stones among which they grow that, 
when not in leaf, it is almost impossible to distinguish them 
(Nature, vol. iii. p. 507). A few cases of what seems to be 
protective mimicry have also been noted, the most curious 
being that of three very rare British fungi, found by Mr. 
Worthington Smith, each in company with common species 
which they so closely resembled that only a minute examina- 
tion could detect the difference. One of the common species 
is stated in botanical works to be " bitter and nauseous," so 
that it is not improbable that the rare kind may escape being 
eaten by being mistaken for an uneatable species, though 
itself palatable. Mr. Mansel Weale also mentions a labiate 
plant, the Ajuga ophrydis, of South Africa, as strikingly 
resembling an orchid. This may be a means of attracting 
insects to fertilise the flower in the absence of sufficient nectar 
or other attraction in the flower itself ; and the supposition is 
rendered more probable by this being the only species of the 
genus Ajuga in South Africa. Many other cases of resem- 
blances between very distinct plants have been noticed — as that 
of some Euphorbias to Cacti; but these very rarely inhabit the 
same country or locality, and it has not been proved that there 
is in any of these cases the amount of inter-relation between 
the species which is the essential feature of the protective 
" mimicry " that occurs in the animal world. 

The different colours exhibited by the foliage of plants 
and the changes it undergoes during growth and decay, 
appear to be due to the general laws already sketched out, 
and to have little if any relation to the special requirements 
of each species. But flowers and fruits exhibit definite and 
well-pronounced tints, often varying from species to species, 
and more or less clearly related to the habits and functions of 
the plant. With the few exceptions already pointed out, 
these may be generally classed as attractive colours. 

Attractive Colours of Fruits 

The seeds of plants require to be dispersed so as to reach 
places favourable for germination and growth. Some are 



398 TROPICAL NATURE 



very minute and are carried abroad by the wind, or they are 
violently expelled and scattered by the bursting of the con- 
taining capsules. Others are downy or winged, and are 
carried long distances by the gentlest breeze, or they are 
hooked and stick to the fur of animals. But there is a large 
class of seeds which cannot be dispersed in either of these 
ways, and they are mostly contained in eatable fruits. These 
fruits are devoured by birds or beasts, and the hard seeds 
pass through their stomachs undigested, and, owing probably 
to the gentle heat and moisture to which they have been sub- 
jected, in a condition highly favourable for germination. The 
dry fruits or capsules containing the first two classes of seeds 
are rarely, if ever, conspicuously coloured, whereas the eatable 
fruits almost invariably acquire a bright colour as they ripen, 
while at the same time they become soft and often full of 
agreeable juices. Our red haws and hips, our black elder- 
berries, our Uue sloes and whortleberries, our white mistletoe 
and snowberry, and our orange sea-buckthorn, are examples 
of the colour-sign of edibility ; and in every part of the world 
the same phenomenon is found. Many such fruits are poison- 
ous to man and to some animals, but they are harmless to 
others ; and there is probably nowhere a brightly coloured 
pulpy fruit which does not serve as food for some species of 
bird or mammal. 

Protective Colours of Fruits 

The nuts and other hard fruits of large forest-trees, though 
often greedily eaten by animals, are not rendered attractive 
to them by colour, because they are not intended to be eaten. 
This is evident, for the part eaten in these cases is the seed 
itself, the destruction of which must certainly be injurious to 
the species. Mr. Grant Allen, in his ingenious work on 
Physiological Esthetics, well observes that the colours of all 
such fruits are protective — green when on the tree, and thus 
hardly visible among the foliage, but turning brown as they 
ripen and fall on the ground, as filberts, chestnuts, walnuts, 
beechnuts, and many others. It is also to be noted that 
many of these are specially though imperfectly protected, 
some by a prickly coat as in the chestnuts, or by a nauseous 
covering as in the walnut ; and the reason why the protection 



VI COLOURS OF PLANTS 399 

is not carried farther is probably because it is not needed, 
these trees producing such vast quantities of fruit, that, how- 
ever many are eaten, more than enough are always left to 
produce young plants. In the case of the attractively coloured 
fruits, it is curious to observe how the seeds are always of 
such a nature as to escape destruction when the fruit itself is 
eaten. They are generally very small and comparatively 
hard, as in the strawberry, gooseberry, and fig; if a little 
larger, as in the grape, they are stiU harder and less eatable ; 
in the fruit of the rose or (hip) they are disagreeably hairy ; 
in the orange tribe excessively bitter. When the seeds are 
larger, softer, and more eatable, they are protected by an 
excessively hard and stony covering, as in the plum and 
peach tribe ; or they are enclosed in a tough horny core, as 
with crabs and apples. These last are much eaten by swine, 
and are probably crushed and swallowed without bruising 
the core or the seeds, which pass through their bodies 
undigested. These fruits may also be swallowed by some of 
the larger frugivorous birds, just as nutmegs are swallowed 
by pigeons for the sake of the mace which encloses the nut, 
and which by its brilliant red colour is an attraction as soon 
as the fruit has split open, which it does upon the tree. 

There is, however, one curious case of an attractively 
coloured seed which has no soft eatable covering. The Abrus 
precatoria, or *" rosary bean," is a leguminous shrub or small 
tree growing in many tropical countries, whose pods curl up 
and split open on the tree, displaying the brilliant red seeds 
within. It is very hard and glossy, and is said to be, as 
no doubt it is, " very indigestible." It may be that birds, 
attracted by the bright colour of the seeds, swallow them, 
and that they pass through their bodies undigested, and so 
get dispersed. If so it would be a case among plants analo- 
gous to mimicry among animals — an appearance of edibility 
put on to deceive birds for the plant's benefit. Perhaps it 
succeeds only with young and inexperienced birds, and it 
would have a better chance of success, because such deceptive 
appearances are very rare among plants. 

The smaller plants whose seeds simply drop upon the 
ground, as in the grasses, sedges, composites, umbeUiferse, 
etc., always have dry and obscurely coloured capsules and 



400 TROPICAL NATURE vi 

small brown seeds. Others whose seeds are ejected by the 
bursting open of their capsules, as with the oxalis and many 
of the caryophyllacese, scrophulariacese, etc., have their seeds 
very small and rarely or never edible. 

It is to be remarked that most of the plants whose large- 
seeded nuts cannot be eaten without destroying their germ- 
inating power — as the oaks, beeches, and chestnuts — are 
trees of large size which bear great quantities of fruit, and 
that they are long Hved and have a wide geographical range. 
They belong to what are called dominant groups, and are 
thus able to endure having a large proportion of their seeds 
destroyed with impunity. It is a suggestive fact that they 
are among the most ancient of known dicotyledonous plants — 
oaks and beeches going back to the Cretaceous period with 
little change of type, so that it is not improbable that they 
may be older than any fruit-eating mammal adapted to feed 
upon their fruits. The attractive coloured fruits on the other 
hand, having so many special adaptations to dispersal by 
birds and mammals, are probably of more recent origin.^ 
The apple and plum tribes are not known earlier than the 
Miocene period ; and although the record of extinct vegetable 
life is extremely imperfect, and the real antiquity of these 
groups is no doubt very much greater, it is not improbable 
that the comparative antiquity of the fruit-bearing and nut- 
bearing trees may remain unchanged by further discoveries, 
as has almost always happened as regards the comparative 
antiquity of animal groups. 

Attractive Colours of Flowers 

The colours of flowers serve to render them visible and 
recognisable by insects, which are attracted by secretions of 
nectar or pollen. During their visits for the purpose of 
obtaining these products, insects involuntarily carry the 
pollen of one flower to the stigma of another, and thus efiect 
cross -fertilisation, which, as Mr. Darwin was the first to 
demonstrate, immensely increases the vigour and fertility of 
the next generation of plants. This discovery has led to 
the careful examination of great numbers of flowers, and the 

' I owe this lemark to Mr. Grant AUen, author of Physiologwal 

Esthetics. 



VI COLOUKS OF PLANTS 401 

result has been that the most wonderful and complex arrange- 
ments have been found to exist, all having for their object to 
secure that flowers shall not be self-fertilised perpetually, but 
that pollen shall be carried, either constantly or occasionally, 
from the flowers of one plant to those of another. Mr. 
Darwin himself first worked out the details in orchids, 
primulas, and some other groups, and hardly less curious 
phenomena have since been found to occur even among some 
of the most regularly -formed flowers. The arrangement, 
length, and position of all the parts of the flower is now 
found to have a purpose, and not the least remarkable por- 
tion of the phenomenon is the great variety of ways in which 
the same result is obtained. After the discoveries with 
regard to orchids, it was to be expected that the irregular, 
tubular, and spurred flowers should present various curious 
adaptations for fertilisation by insect -agency. But even 
among the open, cup -shaped, and quite regular flowers, in 
which it seemed inevitable that the pollen must fall on the 
stigma and produce constant self -fertilisation, it has been 
found that this is often prevented by a physiological varia- 
tion — the anthers constantly emitting their pollen either a 
little earlier or a little later than the stigmas of the same 
flower, or of other flowers on the same plant, were in the 
best state to receive it ; and as individual plants in different 
stations, soils, and aspects differ somewhat in the time of 
flowering, the pollen of one plant would often be conveyed 
by insects to the stigmas of some other plant in a condition 
to be fertilised by it. This mode of securing cross-fertilisation 
seems so simple and easy that we can hardly help wondering 
why it did not always come into action, and so obviate the 
necessity for those elaborate, varied, and highly complex 
contrivances found perhaps in the majority of coloured 
flowers. The answer to tMs of course is, that variation some- 
times occurred most freely in one part of a plant's organisation 
and sometimes in another, and that the benefit of cross-fertili- 
sation was so great that any variation that favoured it was 
preserved, and then formed the starting-point of a whole 
series of further variations, resulting in those marvellous 
adaptations for insect fertilisation which have given much of 
their variety, elegance, and beauty to the floral world. For 

2d 



402 TROPICAL KATUEE Vi 

details of these adaptations we must refer the reader to the 
works of Darwin, Lubbock, Herman Miiller, and others. We 
have here only to deal with the part played by colour, and 
by those floral structures in which colour is most displayed. 

Attractive Odours in Flowers 

The sweet odours of flowers, like their colours, seem 
to have been developed as an attraction or guide to insect 
fertilisers, and the two phenomena are often complementary 
to each other. Thus, many inconspicuous flowers, like the 
mignonette and the sweet-violet, can be distinguished by 
their odours before they attract the eye, and this may often 
prevent their being passed unnoticed; while very showy 
flowers, and especially those with variegated or spotted petals, 
are seldom sweet. White, or very pale flowers, on the other 
hand, are often excessively sweet, as exemplified by the 
jasmine and clematis ; and many of these are only scented at 
night, as is strikingly the case with the night^smelling stock, 
our butterfly orchis (Habenaria chlorantha), the greenish- 
yellow Daphne pontica, and many others. These white 
flowers are mostly fertilised by nigh1>flying moths, and those 
which reserve their odours for the evening probably escape 
the visits of diurnal insects, which would consume their 
nectar without efiecting fertilisation. The absence of odour 
in showy flowers, and its preponderance among those that 
are white, may be shown to be a fact by an examination of 
the lists in Mr. Mongredien's work on hardy trees and shrubs.^ 
He gives a list of about 160 species with showy flowers, and 
another list of sixty species with fragrant flowers ; but only 
twenty of these latter are included among the showy species, 
and these are almost all white flowered. Of the sixty species 
with fragrant flowers, more than forty are white, and a 
number of others have greenish, yellowish, or dusky and 
inconspicuous flowers. The relation of white flowers to 
nocturnal insects is also well shown by those which, like the 
evening primroses, only open their large white blossoms after 
sunset, while most of the yellow species remain open all day. 
The red Martagon lily has been observed by Mr. Herman 

' Trees and Shrubs for Mnglish PlOMtations, by Augustus Mongredien. 
Murray, 1870. 



VI COLOURS OF PLANTS 403 

Miiller to be fertilised by tie humming-bird bawk moth, 
which flies in the morning and afternoon, when the colours of 
this flower, exposed to the nearly horizontal rays of the sun, 
glow with brilliancy, and when it also becomes very sweet- 
scented. 

Attractive Grouping of Flowers 

To the same need of conspicuousness the combination of 
so many individually small flowers into heads and bunches is 
probably due, producing such broad masses as those of the 
elder, the guelder-rose, and most of the Umbelliferee, or such 
elegant bunches as those of the Hlac, laburnum, horse chest- 
nut, and wistaria. In other cases minute flowers are gathered 
into dense heads, as with Globularia, Jasione, clover, and aU 
the Compositse ; and among the latter the outer flowers are 
often developed into a ray, as in the sunflowers, the daisies, 
and the asters, forming a starHke compoimd flower, which is 
itself often produced in immense profusion. 

WTiy Alpine Flowers are so beautiful 

The beauty of Alpine flowers is almost proverbial. It 
consists either in the increased size of the individual flowers 
as compared with the whole plant, in increased intensity of 
colour, or in the massing of small flowers into dense cushions 
of bright colour ; and it is only in the higher Alps, above the 
Hmit of forests and upwards towards the perpetual snow-Hne, 
that these characteristics are fully exhibited. This effort at 
conspicuousness under adverse circumstances may be traced 
to the comparative scarcity of winged insects in the higher 
regions, and to the necessity for attracting them from a dis- 
tance. Amid the vast slopes of debris and the huge masses 
of rock so prevalent in higher mountain regions, patches of 
intense colour can alone make themselves visible and serve to 
attract the wandering butterfly from the valleys. Mr. Herman 
Miiller's careful observations have shown that in the higher 
Alps bees and most other groups of winged insects are almost 
wanting, whUe butterflies are tolerably abundant ; and he has 
discovered that in a number of cases where a lowland flower 
is adapted to be fertilised by bees, its Alpine ally has had its 
structure so modified as to be adapted for fertilisation only 



404 TROPICAL NATURE 



by butterflies.^ But bees are always (in the temperate zone) 
far more abundant than butterflies, and this will be another 
reason why flowers specially adapted to be fertilised by the 
latter should be rendered unusually conspicuous. We find, 
accordingly, the yellow primroses and cowslips of the plains 
replaced by pink and magenta- coloured Alpine species ; the 
straggling wild pinks of the lowlands by the masses of large 
flowers in such mountain species as Dianthus alpinus and D. 
glacialis; the saxifrages of the high Alps with bunches of 
flowers a foot long as in Saxifraga longifolia and S. cotyledon, 
or forming spreading masses of flowers as in S. oppositifoUa ; 
while the soapworts, silenes, and louseworts are equally superior 
to the allied species of the plains. 

Why Allied Species of Flowers differ in Size and Beauty 

Again, Dr. Miiller has discovered that when there are 
showy and inconspicuous species in the same genus of plants, 
there is often a corresponding difference of structure, those 
with large and showy flowers being quite incapable of self- 
fertilisation, and thus depending for their very existence on 
the visits of insects, while the others are able to fertilise 
themselves should insects fail to visit them. We have 
examples of this difference in Malva sylvestris, Epilobium 
angustifolium. Polygonum bistorta, and Geranium pratense — 
which have all large or showy flowers, and must be fertilised 
by insects — as compared with Malva rotundifolia, Epilobium 
parviflorum, Polygomun aviculare, and Geranium pusillum, 
which have small or inconspicuous flowers, and are so con- 
structed that if insects should not visit them they are able to 
fertilise themselves.^ 

Absence of Colow in Wind-fertilised Flowers 
As supplementing these curious facts, showing the relation 
of colour in flowers to the need of the visits of insects to 
fertilise them, we have the remarkable, and, on any other 
theory, utterly inexplicable circumstance that in all the numer- 
ous cases in which plants are fertilised by the agency of 
the wind they never have specially coloiu'ed floral envel- 
opes. Such are our pines, oaks, poplars, willows, beeches, 
1 Nature, vol. xi. pp. 82, 110. a lb., vol. ix. p. 164. 



VI COLOURS OF PLANTS 405 

and hazel, our nettles, grasses, sedges, and many others. In 
some of these the male flowers are very conspicuous, as the 
catkins of the willows, and these secrete honey and attract 
numerous insects at a season when there are few other flowers, 
and thus secure cross -fertilisation. Sedges and grasses are 
also occasionally visited by insects. 

The same Theory of Colour applicable to Animals ami Plants 

It may he thought that this absence of colour where it is 
not wanted is opposed to the view maintained in the earlier 
part of the preceding chapter, that colour is normal and is 
constantly tending to appear in natural objects. It must be 
remembered, however, that the green colour of foliage, due to 
chlorophyll, prevails throughout the greater part of the vege- 
table kingdom, and has, almost certainly, persisted through 
long geological periods. It has thus acquired a fixity of 
character which cannot be readily disturbed ; and, as a matter 
of fact, we find that colour rarely appears in plants except in 
association with a considerable modification of leaf-texture, 
such as occurs in the petals and coloured sepals of flowers. 
Wind -fertilised plants never have such specially organised 
floral envelopes, and, in most cases, are entirely without a 
calyx or corolla. The connection between modification of 
leaf -structure and colour is further seen in the greater amount 
and variety of colour in irregular than in regular flowers. 
The latter, which are least modified, have generally uniform 
or but slightly varied colours, while the former, which have 
undergone great modification, present an immense range of 
colour and marking, culminating in the spotted and varie- 
gated flowers of such groups as the Scrophularinese and 
Orchidese. The same laws as to the conditions of a maximum 
production of colour are thus found to obtain both in plants 
and animals. 

Relation of the Colours of Flowers and their Geographical 



The adaptation of flowers to be fertilised by insects — 
often to such an extent that the very existence of the species 
depends upon it — has had an important influence on the dis- 
tribution of plants and the general aspects of vegetation. 



406 TROPICAL NATURE 



The seeds of a particular species may be carried to another 
country, may find there a suitable soil and climate, jnay grow 
and produce flowers ; but if the insect which alone can fertilise 
it should not inhabit that country, the plant cannot maintain 
itself, however frequently it may be introduced or however 
vigorously it may grow. Thus may probably be explained 
the poverty in flowering-plants and the great preponderance 
of ferns that distinguishes many oceanic islands, as well as 
the deficiency of gaily -coloured flowers in others. New 
Zealand is, in proportion to its total number of flowering- 
plants, exceedingly poor in handsome flowers, and it is cor- 
respondingly poor in insects, especially in bees and butterflies, 
the two groups which so greatly aid in fertilisation. In both 
these aspects it contrasts strongly with Southern Australia 
and Tasmania in the same latitudes, where there is a profu- 
sion of gaily -coloured flowers and an exceeding rich insect- 
fauna. Another case is presented by the Galapagos islands, 
which, though situated on the equator ofi' the west coast of 
South America, and with a tolerably luxuriant vegetation in 
the damp mountain zone, yet produce hardly a single con- 
spicuously-coloured flower; and this is correlated with, and 
no doubt dependent on, an extreme poverty of insect life, not 
one bee and only a single butterfly having been found there. 

Again, there is reason to believe that some portion of the 
large size and corresponding showiness of tropical flowers is 
due to their being fertilised by very large insects and even 
by birds. Tropical sphinx-moths often have their probosces 
nine or ten inches long, and we find flowers whose tubes or 
spurs reach about the same length, while the giant bees, and 
the numerous flower-sucking birds, aid in the fertilisation of 
flowers whose corollas or stamens are proportionately large. 

Recent Views as to direct Action of Light on the Colours of 
Flowers and Fruits 

The theory that the brilliant colours of flowers and fruits 
are due to the direct action of light has been supported by a 
recent writer by examples taken from the arctic instead of 
from the tropical flora. In the arctic regions vegetation is 
excessively rapid during the short summer, and this is held 
to be due to the continuous action of light throughout the 



VI COLOURS OF PLANTS 407 

long summer days. " The farther we advance towards the 
north the more the leaves of plants increase in size, as if to 
absorb a greater proportion of the solar rays. M. Grisebach 
says that during a journey in Norway he observed that the 
majority of deciduous trees had already, at the 60th degree 
of latitude, larger leaves than in Germany, while M. Oh. 
Martins has made a similar observation as regards the legu- 
minous plants cultivated in Lapland."^ The same writer goes 
on to say that aU the seeds of cultivated plants acquire a 
deeper colour the farther north they are grown, white hari- 
cots becoming brown or black, and white wheat becoming 
brown, while the green colour of all vegetation becomes more 
intense. The flowers also are similarly changed : those which 
are white or yellow in central Europe becoming red or orange 
in Norway. This is what occurs in the Alpine flora, and the 
cause is said to be the same in both — the greater intensity of 
the sunUght. In the one the light is more persistent, in the 
other more intense because it traverses a thinner atmosphere. 
Admitting the facts as above stated to be in themselves 
correct, they do not by any means establish the theory 
founded on them ; and it is curious that Grisebach, who has 
been quoted by this writer for the fact of the increased size 
of the foliage, gives a totally different explanation of the 
more vivid colours of arctic flowers. He says : " We see 
flowers become larger and more richly coloured in proportion 
as, by the increasing length of winter, insects become rarer, 
and their co-operation in the act of fecundation is exposed to 
more uncertain chances" (Vegetation du Globe, vol. i. p. 61 — 
French translation). This is the theory here adopted to 
explain the coloiu-s of Alpine plants, and we believe there are 
many facts that wiU show it to be the preferable one. The 
statement that the white and yellow flowers of temperate 
Europe become red or golden in the arctic regions must, we 
think, be incorrect. By roughly tabulating the colours of 
the plants given by Sir Joseph Hooker^ as permanently 
arctic, we find among fifty species with more or less con- 
spicuous flowers, twenty -five white, twelve yellow, eight 

^ Bemie des Deux Mondes, 1877 — "La Vegetation dans les hautes Lati- 
tudes," par M. Tisserand. 

2 " On the pistribi»tion of Arctic Plj^nts," Linn. Trans, vol. xxiii. (1862). 



408 TROPICAL NATURE vi 

purple or blue, three lilac, and two red or pink, showing a 
very similar proportion of white and yellow flowers to what 
obtains farther south. 

We have, however, a remarkable flora in the southern 
hemisphere, which affords a crucial test of the theory of greater 
intensity of light being the direct cause of brilliantly-coloured 
flowers. The Auckland and Campbell's islands, south of New 
Zealand, are in the same latitude as the middle and the south 
of England, and the summer days are therefore no longer 
than with us. The climate, though cold, is very uniform, 
and the weather "very rainy and stormy." It is evident, 
then, that there can be no excess of sunshine above what we 
possess, yet in a very limited flora there are a number of 
flowers which — Sir Joseph Hooker states — are equal in 
brilliancy to those of the arctic flora. These consist of 
brilliant gentians, handsome veronicas, large and magnificent 
Compositse with purple flowers, bright ranunculi, showy 
Umbelliferse, and the golden -flowered Ohrysobactron Eossii, 
one of the finest of the Asphodelese. ^ All these fine plants, 
it must be remembered, are peculiar to these islands, and 
have therefore been developed under the climatal conditions 
that prevail there ; and as we have no reason to suppose that 
these conditions have undergone any recent change, we may 
be quite sure that an excess of light has had nothing to do 
with the development of these exceptionally bright and hand- 
some flowers. Unfortunately we have no information as to 
the insects of these islands, but from their scarcity in New 
Zealand we can hardly expect them to be otherwise than very 
scarce. There are, however, two species of honey -sucking 
birds (Prosthemadera and Anthornis), as well as a small 
warbler (Myiomoira); and we may be pretty sure that the 
former at least visit these large and handsome flowers, and 
so eff'ect their fertilisation. The most abundant tree on the 
islands is a species of Metrosideros, and we know that trees 
of this genus are common in the Pacific islands, where they 
are almost certainly fertilised by the same family of Meli- 
phagidse or honey-sucking birds. 

I have now concluded this sketch of the general pheno- 
' Coloured figures of all these plants are given in the Flora Antarctica, vol, i. 



VI COLOURS OF PLANTS 409 

mena of colour in the organic world. I have shown reasons 
for believing that its presence, in some of its infinitely-varied 
hues, is more probable than its absence, and that variation of 
colour is an almost necessary concomitant of variation of struc- 
ture, of development, and of growth. It has also been shown 
how colour has been appropriated and modified both in the 
animal and vegetable worlds for the advantage of the species 
in a great variety of ways, and that there is no need to call 
in the aid of any other laws than those of organic develop- 
ment and " natural selection " to explain its countless modifi- 
cations. From the point of view here taken, it seems at once 
improbable and unnecessary that the lower animals should 
have the same delicate appreciation of the infinite variety 
and beauty, of the delicate contrasts and subtle harmonies of 
colour, which are possessed by the more intellectual races of 
mankind, since even the lower human races do not possess it. 
All that seems required in the case of animals is a perception 
of distinctness or contrast of colours ; and the dislike of so 
many creatures to scarlet may perhaps be due to the rarity 
of that colour in nature, and to the glaring contrast it ofiers 
to the sober greens and browns which form the general cloth- 
ing of the earth's surface, though it may also have a direct 
irritating effect on the retina. 

The general view of the subject now given must convince 
us that, so far from colour being — as it has sometimes been 
thought to be — unimportant, it is intimately connected with 
the very existence of a large proportion of the species of the 
animal and vegetable worlds. The gay colours of the butter- 
fly and of the Alpine flower which it unconsciously fertilises 
while seeking for its secreted honey, are each beneficial to its 
possessor, and have been shown to be dependent on the same 
class of general laws as those which have determined the 
form, the structure, and the habits of every living thing. 
The complex laws and unexpected relations which we have 
seen to be involved in the production of the special colours of 
flower, bird, and insect must give them an additional interest 
for every thoughtful mind; while the knowledge that, in 
all probability, each style of coloration, and sometimes the 
smallest details, have a meaning and a use must add a new 
charm to the study of nature. 



410 TROPICAL NATURE 



ON THE ORIGIN OF THE COLOUR-SENSE 

Throughout the preceding discussion we have accepted 
the subjective phenomena of coloiu- — that is, our perception 
of varied hues and the mental emotions excited by them — as 
ultimate facts needing no explanation. Yet they present 
certain features well worthy of attention, a brief considera- 
tion of which will form a fitting sequel to the present essay. 

The perception of colour seems, to the present writer, the 
most wonderful and the most mysterious of our sensations. 
Its extreme diversities and exquisite beauties seem out of 
proportion to the causes that are supposed to have produced 
them, or the physical needs to which they minister. If we 
look at pure tints of red, green, blue, and yellow, they appear 
so absolutely contrasted and unlike each other, that it is 
almost impossible to believe (what we nevertheless know to 
be the fact) that the rays of light producing these very dis- 
tinct sensations differ only in wave-length and rate of vibra- 
tion, and that there is from one to the other a continuous 
series and gradation of such vibrating waves. The positive 
diversity we see in them must then depend upon special 
adaptations in ourselves ; and the question arises, For what 
purpose have our visual organs and mental perceptions become 
so highly specialised in this respect? 

When the sense of sight was first developed in the animal 
kingdom, we can hardly doubt that what was perceived was 
light only, and its more or less complete withdrawal. As the 
sense became perfected, more delicate gradations of light, and 
shade would be perceived, and there seems no reason why a 
visual capacity might not have been developed as perfect as 
our own, or even more so in respect of light and shade, but 
entirely insensible to difierences of colour, except in so far 
as these implied a difference in the quantity of light. The 
world would in that case appear somewhat as we see it in 
good stereoscopic photographs; and we all know how ex- 
quisitely beautiful such pictures are, and how completely 
they give us all requisite information as to form, surface- 
texture, solidity, and distance, and even to some extent as to 
colour, for almost all colours are distinguishable in a photo- 
graph by some differences of tint, and it is quite conceivable 



VI ORIGIN OF THE COLOUR-SENSE 411 

that visual orgajis might exist which would differentiate what 
we term colour by delicate gradations of some one charac- 
teristic neutral tint. Now such a capacity of vision would 
be simple as compared with that which we actually possess, 
which, besides distinguishing infinite gradations of the qmrir 
tity of hght, distinguishes also, by a totally distinct set of 
sensations, gradations of quality, as determined by differences 
of- wave-lengths or rate of vibration. At what grade in 
animal development this new and more complex sense first 
began to appear we have no means of determining. The 
fact that the higher vertebrates, and even some insects, dis- 
tinguish what are to us diversities of colour by no means 
proves that their sensations of colour bear any resemblance 
whatever to ours. An insect's capacity to distinguish red 
from blue or yellow may be (and probably is) due to percep- 
tions of a totally distinct nature, and quite unaccompanied by 
any of that sense of enjoyment or even of radical distinctness 
which pure colours excite in us. Mammalia and birds, whose 
structure and emotions are so similar to our own, do probably 
receive somewhat similar impressions of colour ; but we have 
no evidence to show that they experience pleasurable emotions 
from colour itself when not associated with the satisfaction of 
their wants or the gratification of their passions. 

The primary necessity which led to the development of 
the sense of colour was probably the need of distinguishing 
objects much alike in form and size, but differing in important 
properties, such as ripe and unripe, or eatable and poisonous 
fruits, flowers with honey or without, the sexes of the same 
or of closely aUied species. In most cases the strongest con- 
trast would be the most useful, especially as the colours of 
the objects to be distinguished would form but minute spots 
or points when compared with the broad masses of tint of 
sky, earth, or foliage against which they would be set. 

Throughout the long epochs in which the sense of sight 
was being gradually developed in the higher animals, their 
visual organs would be mainly subjected to two groups of 
rays — rthe green from vegetation, and the blue from the sky. 
The immense preponderance of these over all other groups of 
rays would naturally lead the eye to become specially adapted 
for their perception; and it is quite possible that at first 



412 TROPICAL NATURE 



these were the only kinds of light-vibrations which could be 
perceived at all. When the need for differentiation of colour 
arose, rays of greater and of smaller wave-lengths would 
necessarily be made use of to excite the new sensations required, 
and we can thus understand why green and blue form the 
central portion of the visible spectrum, and are the colours 
which are most agreeable to us in large surfaces ; while at its 
two extremities we find yellow, red, and violet — colours 
which we best appreciate in smaller masses, and when con- 
trasted with the other two, or with light neutral tints. We 
have here probably the foundations of a natural theory of 
harmonious colouring, derived from the order in which oiu* 
colour-sensations have arisen and the nature of the emotions 
with which the several tints have been always associated. 
The agreeable and soothing influence of green light may be 
in part due to the green rays having little heating power ; 
but this can hardly be the chief cause, for the blue and violet, 
though they contain less heat, are not generally felt to be so 
cool and sedative. But when we consider how dependent are 
all the higher animals on vegetation, and that man himself 
has been developed in the closest relation to it, we shall find, 
probably, a sufficient explanation. The green mantle with 
which the earth is overspread caused this one colour to pre- 
dominate over all others that meet our sight, and to be almost 
always associated with the satisfaction of human wants. 
Where the grass is greenest, and vegetation most abundant 
and varied, there has man always found his most suitable 
dwelling-place. In such spots hunger and thirst are unknown, 
and the choicest productions of nature gratify the appetite 
and please the eye. In the greatest heats of summer, cool- 
ness, shade, and moisture are found in the green forest glades, 
and we can thus understand how our visual apparatus has 
become especially adapted to receive pleasurable and soothing 
sensations from this class of rays. 

Supposed increase of Colour-perception within the Historical Period 

Some writers believe that our power of distinguishing 
colours has increased even in historical times. The subject 
has attracted the attention of German philologists, and I have 
been furnished by a friend with some notes from a work of 



VI ORIGIN OP THE COLOUR-SENSE 413 

the late Lazarus Geiger, entitled, Zur Bntioickelungs-geschichte 
der Menschheit (Stuttgart, 1871). According to this writer it 
appears that the colour of grass and foliage is never alluded to 
as a beauty in the Vedas or the Zendavesta, though these 
productions are continually extolled for other properties. 
Blue is described by terms denoting sometimes green, some- 
times black, shovsdng that it was hardly recognised as a 
distinct colour. The colour of the sky is never mentioned in 
the Bible, the Vedas, the Homeric poems, or even in the 
Koran. The first distinct allusion to it known to Geiger is 
in an Arabic work of the ninth century. "Hyacinthine 
locks" are black locks, and Homer calls iron "violet- 
coloured." Yellow was often confounded with green, but, 
along with red, it was one of the earliest colours to receive a 
distinct name. Aristotle names three colours in the rainbow 
— red, yeUow, and green. Two centuries earlier Xenophanes 
had described the rainbow as purple, reddish, and yellow. 
The Pythagoreans admitted four primary colours — white, 
black, red, and yellow; the Chinese the same, with the 
addition of green. 

Simultaneously with the first publication of this essay in 
Macmillan's Magazine, there appeared in the Nineteenth Century 
an article by Mr. Gladstone on the Colour-sense, chiefly as 
exhibited in the poems of Homer. He shows that the few 
colour-terms used by Homer are applied to such difierent 
objects that they cannot denote colours only, as we perceive 
and differentiate them, but seem more applicable to different 
intensities of light and shade. Thus, to give one example, 
the word porphwreos is applied to clothing, to the rainbow, 
to blood, to a cloud, to the sea, and to death ; ajid no one 
meaning wiU suit all these applications except comparative 
darkness. In other cases the same thing has many different 
epithets applied to it according to its different aspects or 
conditions; and as the colours of objects are generally in- 
dicated in ancient writings by comparative rather than by 
abstract terms, — as wine-colour, fire-colour, bronze-colour, etc., 
— it becomes stiU more difficult to determine in any par- 
ticular case what colour was really meant. Mr. Gladstone's 
general conclusion is, that the archaic man had a positive 
perception only of degrees of light and darkness, and that in 



414 TROPICAL NATURE vi 

Homer's time lie had advanced to the imperfect discrimina- 
tion of red and yellow, but no further ; the green of grass 
and foliage or the blue of the sky being never once referred to. 
These curious facts cannot, however, be held to prove so 
recent an origin for colour-sensations as they would at first 
sight appear to do, because we have seen that both flowers 
and fruits have become diversely coloured in adaptation to 
the visual powers of insects, birds, and mammals. Eed 
being a very common colour of ripe fruits which attract birds 
to devour them and thus distribute their seeds, we may be 
sure that the contrast of red and green is to them very well 
marked. It is indeed just possible that birds may have a 
more advanced development of the colour-sense than mam- 
mals, because the teeth of the latter commonly grind up and 
destroy the seeds of the larger fruits and nuts which they 
devour, and which are not usually coloured ; but the irritat- 
ing effect of bright colours on some of them does not support 
this view. It seems most probable, therefore, that man's 
perception of colour in the time of Homer was little if any 
inferior to what it is now, but that, owing to a variety of 
causes, no precise nomenclature of colours had become estab- 
lished. One of these causes probably was, that the colours 
of the objects of most importance, and those which were most 
frequently referred to in songs and poems, were uncertain 
and subject to variation. Blood was light or dark red, or 
when dry, blackish ; iron was gray or dark or rusty ; bronze 
was shining or dull; foliage was of all shades of yellow, 
green, or brown ; and horses or cattle had no one distinctive 
colour. Other objects, as the sea, the sky, and wine, changed 
in tint according to the light, the time of day, and the mode 
of viewing them ; and thus colour, indicated at first by refer- 
ence to certain coloured objects, had no fixity. Things which 
had more definite and purer colours — as certain species of 
flowers, birds, and insects — were probably too insignificant or 
too much despised to serve as colour-terms ; and even these 
often vary, either in the same or in allied species, in a manner 
which would render their use unsuitable. Colour-names, 
being abstractions, must always have been a late development 
in language, and their comparative unimportance in an early 
state of society and of the arts would still further retard their 



vt ORIGIN OF THE COLOUR-SENSE 415 

appearance ; and this seems quite in accordance with the vari- 
ous facts set forth by Mr. Gladstone and the other writers 
referred to. The fact that colour-blindness is so prevalent 
even now is, however, an indication that the fully-developed 
colour-sense is not of primary importance to man. If it had 
been so, natural selection would long ago have eliminated the 
disease itself, and its tendency to recur would hardly be so 
strong as it appears to be. 

Ooncluding Bemarks on the Colour-sense 

The preceding considerations enable us to comprehend 
both why a perception of difference of colour has become 
developed in the higher animals, and also why colours require 
to be presented or combined in varying proportions in order 
to be agreeable to us. But they hardly seem to afford a 
sufficient explanation either of the wonderful contrasts and 
total unlikeness of the sensations produced in us by the chief 
primary colours, or of the exquisite charm and pleasure we 
derive from colour itself, as distinguished from variously- 
coloured objects, in the case of which association of ideas 
comes into play. It is hardly conceivable that the material 
uses of colour to animals and to ourselves required such very 
distinct and powerfully-contrasted sensations ; and it is stiU 
less conceivable that a sense of delight in colour ^er se should 
have been necessary for our utilisation of it. 

The emotions excited by colour and by music alike seem 
to rise above the level of a world developed on purely utili- 
tarian principles. 



YII 

THE ANTIQUITY AND OKIGIN OF MAN^ 

Indications of Man's Extreme Antiquity— Antiquity of Intellectual Man — 
Sculptures on Easter Island — North American Earthworks — The 
Great Pyramid — Conclusion. 

Many now living remember the time (for it is little more than 
twenty years ago) when the antiquity of man, as now under- 
stood, was universally discredited. Not only theologians, 
but even geologists, then taught us that man belonged 
altogether to the existing state of things ; that the extinct 
animals of the Tertiary period had finally disappeared, and 
that the earth's surface, had assumed its present condition, 
before the human race first came into existence. So pre- 
possessed were even scientific men with this idea — which yet 
rested on purely negative evidence, and could not be sup- 
ported by any arguments of scientific value — that numerous 
facts which had been presented at intervals for half a century, 
all tending to prove the existence of man at very remote 
epochs, were silently ignored ; and, more than this, the 
detailed statements of three distinct and careful observers, 
confirming each other, were rejected by a great scientific 
Society as too improbable for publication, only because they 
proved (if they were true) the coexistence of man with extinct 
animals.^ 

^ This formed part of the author's address to the Biological Section of the 
British Association at Glasgow in 1876. 

^ In 1854 (?) a communication from the Torquay Natural History Society 
confirming previous accounts by Mr. Godwin-Austen, Mr. Vivian, and the 
Rev. Mr. M'Enery, that worked flints occurred in Kent's Hole with remains of 
extinct species, was rejected as too improbable for publication. See Lubbock's 
Prehistoric Times, 2d ed., p. 306. 



VII THE ANTIQUITY AND ORIGm OF MAN 417 

But this state of belief in opposition to facts could not 
long continue. In 1859 a few of our most eminent geologists 
examined for themselves into the alleged occurrence of flint 
implements in the gravels of the north of France, which had 
been made public fourteen years before, and found them 
strictly correct. The caverns of Devonshire were about the 
same time carefully examined by equally eminent observers, 
and were found fully to bear out the statements of those 
who had published their results eighteen years before. Flint 
implements began to be found in all suitable localities in 
the south of England, when carefully searched for, often in 
gravels of equal antiquity with those of France. Caverns 
giving evidence of human occupation at various remote 
periods were explored in Belgium and the south of France — 
lake-dwelKngs were examined in Switzerland — refuse-heaps in 
Denmark — and thus a whole series of remains have been 
discovered carrying back the history of mankind from the 
earliest historic periods to a long distant past. 

The antiquity of the races thus discovered cannot be 
measured in years ; but it may be approximately determined 
by the successively earlier and earlier stages of civilisation 
through which we can trace them, and by the changes in 
physical geography and of animal and vegetable life that 
have since occurred. As we go back metals soon disappear, 
and we find only tools and weapons of stone and of bone. 
The stone weapons get ruder and ruder ; pottery, and then 
the bone implements, cease to occur; and in the earliest 
stage we find only chipped flints of rude design, though 
still of unmistakably human workmanship. In like manner 
domestic animals disappear as we go backward ; and though 
the dog seems to have been the earliest, it is doubtful 
whether the makers of the ruder flint implements of the 
gravels possessed even this. Still more important as a 
measure of time are the changes in the distribution of 
animals, indicating changes of climate, which have occurred 
during the human period. At a comparatively recent epoch 
in the record of prehistoric times we find that the Baltic 
was far Salter than it is now and produced abundance of 
oysters, and that Denmark was covered with pine forests 
inhabited by Capercailzies, such as now only occur farther 

2e 



418 TROPICAL NATURE 



north in Norway. A little earlier we find that reindeer 
were common even in the south of France ; and still earlier 
this animal was accompanied by the mammoth and woolly 
rhinoceros, by the arctic glutton, and by huge bears and 
lions of extinct species. The presence of such animals impUes 
a change of climate ; and both in the caves and gravels we 
find proofs of a much colder climate than now prevails in 
Western Europe. Even more remarkable are the changes 
of the earth's surface which have been effected during man's 
occupation of it. Many extensive valleys in England and 
France are believed by the best observers to have been 
deepened at least a hundred feet ; caverns now far out of the 
reach of any stream must for a long succession of years have 
had streams flowing through them, at least in times of 
floods ; and this often implies that vast masses of solid rock 
have since been worn away. In Sardinia land has risen at 
least 300 feet since men lived there who made pottery and 
probably used fishing-nets ; ' while in Kent's Cavern remains 
of man are found buried beneath two separate beds of 
stalagmite, each having a distinct texture, and each covering 
a deposit of cave -earth having well-marked differential 
characters, while each contains a distinct assemblage of 
extinct animals. 

Such, briefly, are the results of the evidence that has 
been rapidly accumulating for about fifteen years, as to 
the antiquity of man; and it has been confirmed by so 
many discoveries of a like nature in all parts of the globe, 
and especially by the comparison of the tools and weapons 
of prehistoric man with those of modern savages (so that 
the use of even the rudest flint implements has become 
quite intelligible), that we can hardly wonder at the vast 
revolution effected in public opinion. Not only is the 
belief in man's vast and still unknown antiquity universal 
among men of science, but it is hardly disputed by any well- 
informed theologian ; and the present generation of science- 
students must, we should think, be somewhat puzzled to 
understand what there was in the earliest discoveries that 
should have aroused such general opposition, and been met 
with such universal incredulity. 

1 Lyell's Antiquity of Mam, 4th ed., p. 115. 



vn THE ANTIQUITY AND ORIGIN OF MAN 419 

But the question of the mere "Antiquity of Man" 
almost sank into insignificance at a very early period of 
the inquiry, in comparison with the far more momentous 
and more exciting problem of the development of man from 
some lower animal form, which the theories of Mr. Darwin 
and of Mr. Herbert Spencer soon showed to be inseparably 
bound up with it. This has been, and to some extent still 
is, the subject of fierce conflict ; but the controversy as to the 
fact of such development is now almost at an end, since one 
of the most talented representatives of Cathohc theology, 
and an anatomist of high standing — Professor Mivart — fiJly 
adopts it as regards physical structure, reserving his opposi- 
tion for those parts of the theory which would deduce man's 
whole intellectual and moral nature from the same source and 
by a similar mode of development. 

Never, perhaps, in the whole history of science or philo- 
sophy has so great a revolution in thought and opinion been 
effected as in the twelve years from 1859 to 1871, the 
respective dates of publication of Mr. Darwin's Origin of 
Species and Descent of Man. Up to the commencement 
of this period the belief in the independent creation or 
origin of the species of animals and plants, and the very 
recent appearance of man upon the earth, were, practically, 
universal. Long before the end of it these two beliefs had 
utterly disappeared, not only in the scientific world, but 
almost equally so among the literary and educated classes 
generally. The belief in the independent origia of man held 
its ground somewhat longer; but the publication of Mr. 
Darwin's great work gave even that its deathblow, for hardly 
any one capable of judging of the evidence now doubts the 
derivative nature of man's bodily structure as a whole, 
although many believe that his mind, and even some of his 
physical characteristics, may be due to the action of other 
forces than have acted in the case of the lower animals. 

We need hardly be surprised, under these circumstances, 
if there has been a tendency among men of science to pass 
from one extreme to the other ; from a profession (so few 
years ago) of total ignorance as to the mode of origin of all 
living things, to a claim to almost complete knowledge of the 
whole progress of the universe, from the first speck of living 



420 TROPICAL NATURE 



protoplasm up to the highest development of the human 
intellect. Yet this is really what we have seen in the last 
sixteen years. Formerly difficulties were exaggerated, and it 
was asserted that we had not sufficient knowledge to venture 
on any generalisations on the subject. Now difficulties are set 
aside, and it is held that our theories are so well established 
and so far-reaching that they explain and comprehend all 
nature. It is not long ago (as I have already reminded 
you) since fads were contemptuously ignored, because they 
favoured our now popular views; at the present day it 
seems to me that facts which oppose them hardly receive 
due consideration. And as opposition is the best incentive 
to progress, and it is not well even for the best theories to 
have it all their own way, I propose to direct your attention 
to a few such facts, and to the conclusions that seem fairly 
deducible from them. 

Indications of Man's Hxtreme Antiquity 

It is a curious circumstance that, notwithstanding the 
attention that has been directed to the subject in every part 
of the world, and the numerous excavations connected with 
railways and mines, which have offered such facilities for 
geological discovery, no advance whatever has been made for 
a considerable number of years in detecting the time or mode 
of man's origin. The Palaeolithic flint weapons first dis- 
covered in the north of France more than thirty years ago 
are still the oldest undisputed proofs of man's existence; 
and amid the countless relics of a former world that have* 
been brought to light, no evidence of any one of the links 
that must have connected man with the lower animals has 
yet appeared. 

It is, indeed, well known that negative evidence in 
geology is of very slender value; and this is, no doubt, 
generally the case. The circumstances here are, however, 
peculiar, for many converging lines of evidence show that, 
on the theory of development by the same laws which have 
determined the development of the lower animals, man must 
be immensely older than any traces of him yet discovered. 
As this is a point of great interest we must devote a few 
moments to its consideration. 



VII THE ANTIQUITY AND ORIGIN OF MAN 421 

1. The most important difference between man and sucli 
of tte lower animals as most nearly approach him is un- 
doubtedly in the bulk and development of his brain, as 
indicated by the form and capacity of th» cranium. We 
should therefore anticipate that these earliest races, who were 
contemporary with the extinct animals and used rude stone 
weapons, would show a marked deficiency in this respect. 
Yet the oldest known crania (those of the Engis and Cro- 
Magnon caves) show no marks of degradation. The former 
does not present so low a type as that of most existing 
savages, but is (to use the words of Professor Huxley) "a 
fair average human skull, which might have belonged to a 
philosopher, or might have contained the thoughtless brains 
of a savage." The latter are still more remarkable, being 
unusually large and well-formed. Dr. Pruner-Bey states that 
they surpass the average of modern European skuUs in 
capacity, while their symmetrical form, without any trace 
of prognathism, compares favourably not only with those of 
the foremost savage races, but with many civilised nations 
of modern times. 

One or two other crania of much lower type, but of less 
antiquity than this, have been discovered; but they in no 
way invalidate the conclusion which so highly developed a 
form at so early a period implies, viz. that we have as yet 
made a hardly perceptible step towards the discovery of any 
earlier stage in the development of man. 

2. This conclusion is supported and enforced by the 
nature of many of the works of art found even in the oldest 
cave-dwellings. The flints are of the old chipped type, but 
they are formed into a large variety of tools and weapons — 
such as scrapers, awls, hammers, saws, lances, etc., implying 
a variety of purposes for which these were used, and a 
corresponding degree of mental activity and civilisation. 
Numerous articles of bone have also been found, including 
well-formed needles ; implying that skins were sewn together, 
and perhaps even textile materials woven into cloth. StiU 
more important are the numerous carvings and drawings 
representing a variety of animals, including horses, reindeer, 
and even a mammoth, executed with considerable skill on 
bone, reindeer-horns, and mammoth -tusks. These, taken 



422 TROPICAL NATURE 



together, indicate a state of civilisation much higher than 
that of the lowest of our modern savages, while they are 
quite compatible with a considerable degree of mental ad- 
vancement, and lead us to believe that the crania of Engis 
and Cro-Magnon are not exceptional, but fairly represent the 
characters of the race. If we further remember that these 
people lived in Europe under the unfavourable conditions of 
a sub-arctic climate, we shall be inclined to agree with Dr. 
Daniel Wilson that it is far easier to produce evidences of 
deterioration than of progress, in instituting a comparison 
between the contemporaries of the mammoth and later 
prehistoric races of Europe or savage nations of modern 
times. 1 

3. Yet another important line of evidence as to the 
extreme antiquity of the human type has been brought 
prominently forward by Professor Mivart.^ He shows, by a 
careful comparison of all parts of the structure of the body, 
that man is related not to any one, but almost equally to 
many of the existing apes — to the orang, the chimpanzee, 
the gorilla, and even to the gibbons, in a variety of ways ; 
and these relations and differences are so numerous and so 
diverse that, on the theory of evolution, the ancestral form 
which ultimately developed into man must have diverged 
from the common stock whence all these various forms and 
their extinct allies originated. But so far back as the 
Miocene deposits of Europe we find the remains of apes 
allied to these various forms, and especially to the gibbons ; 
so that in all probability the special line of variation which' 
led up to man branched off at a still earlier period. And 
these early forms, being the initiation of a far higher type, 
and having to develop by natural selection into so specialised 
and altogether distinct a creature as man, must have risen at 
a very early period into the position of a dominant race, and 
spread in dense waves of population over all suitable portions 
of the great continent — for this, on Mr. Darwin's hypothesis, 
is essential to developmental progress through the agency of 
)iatural selection. 

Under these circumstances we might certainly expect to 

^ Prehistoric Man, 3d ed., vol. i. p. 117. 
" Man and Apes, pp. 171-193. 



THE ANTIQUITY AND ORIGIN OF MAN 423 



find some relics of these earlier forms of man along with 
those of animals, which were presumably less abundant. 
Negative evidence of this kind is not very weighty, but still it 
has some value. It has been suggested that as apes are mostly 
tropical, and anthropoid apes are now confined almost ex- 
clusively to the vicinity of the equator, we should expect the 
ancestral forms of man to have inhabited these same localities 
— "West Africa and the Malay islands. But this objection is 
hardly valid, because existing anthropoid apes are wholly 
dependent on a perennial supply of easily accessible fruits, 
which is only found near the equator ; while not only had 
the south of Europe an almost tropical climate in Miocene 
times, but we must suppose even the earliest ancestors of 
man to have been terrestrial and omnivorous, since it must 
have taken ages of slow modification to have produced the 
perfectly erect form, the short arms, and the wholly non- 
prehensile foot,i which so strongly differentiate man from 
the arboreal apes. 

The conclusion which I think we mUst arrive at is, that if 
man has been developed from a common ancestor with all 
existing apes, and by no other agencies than such as have affected 
their development, then he must have existed, in something 
approaching his present form, during the Tertiary period — 
and not merely existed, but predominated in numbers, 
wherever suitable conditions prevailed. If, then, continued 
researches in all parts of Europe and Asia fail to bring to 
light any proofs of his presence, it will be at least a pre- 
sumption that he came into existence at a much later date, 
and by a much more rapid process of development. In that 
case it will be a fair argument that, just as he is in his 
mental and moral nature, his capacities and aspirations, so 
infinitely raised above the brutes, so his origin is due, in part, 

* The common statement of travellers as to savages having great prehensile 
power in the toes has been adopted by some naturalists as indicating an ap- 
proach to the apes. But this notion is founded on a complete misconception. 
Savages pick up objects with their feet, it is true, but always by a lateral 
motion of the toes, which we should equally possess if we never wore shoes or 
stockings. In no savage have I ever seen the slightest approach to opposa- 
bility of the great toe, which is the essential distinguishing feature of apes ; 
nor have I ever seen it stated that any variation in this direction has been 
detected in the anatomical structure of the foot of the lower races. 



424 TROPICAL NATURE 



to distinct and higher agencies than such as have affected 
their development. 

Antiquity of Intellectual Man 

There is yet another line of inquiry bearing upon this 
subject to which I wish to call your attention. It is a some- 
what curious fact that, while all modern writers admit the 
great antiquity of man, most of them maintain the very 
recent development of his intellect, and will hardly con- 
template the possibility of men equal in mental capacity to 
ourselves having existed in prehistoric times. This question 
is generally assumed to be settled by such relics as have been 
preserved of the manufactures of the older races, showing 
a lower and lower state of the arts ; by the successive 
disappearance in early times of iron, bronze, and pottery ; 
and by the ruder forms of the older flint implements. The 
weakness of this argument has been well shown by Mr. 
Albert Mott in his very original but little-known presidential 
address to the Literary and Philosophical Society of Liver- 
pool in 1873. He maintains that " our most distant glimpses 
of the past are still of a world peopled as now with men both 
civilised and savage," and " that we have often entirely mis- 
read the past by supposing that the outward signs of civilisa- 
tion must always be the same, and must be such as are found 
among ourselves." In support of this view he adduces a 
variety of striking facts and ingenious arguments, a few of 
which I will briefly summarise. 

Saulptures on Easter Island 

On one of the most remote islands of the Pacific — ^Easter 
island — 2000 miles from South America, 2000 from the 
Marquesas, and more than 1000 from the Gambler islands, 
are found hundreds of gigantic stone images, now mostly in 
ruins. They are often forty feet high, while some seem to 
have been much larger, the crowns on their heads, cut out of 
a red stone, being sometimes ten feet in diameter, while even 
the head and neck of one is said to have been twenty feet 
high.i These images once all stood erect on extensive stone 
platforms. 

1 Jou/rn. of Roy. Qeog. Soc, 1870, pp. 177, 178. 



VII THE ANTIQUITY AND ORIGIN OF MAN 425 



The island containing these remarkable works of art has 
only an area of about thirty square miles, or considerably less 
than Jersey. Now, as one of the smallest images (eight feet 
high) weighs four tons, the largest must weigh over a 
hundred tons, if not much more ; and the existence of such 
vast works implies a large population, abundance of food, and 
an established government. Yet how could these coexist on 
a mere speck of land wholly cut off from the rest of the 
world ? Mr. Mott maintains that these facts necessarily 
imply the power of regular communication with larger islands 
or a continent, the arts of navigation, and a civilisation much 
higher than now exists in any part of the Pacific. Very 
similar remains in other islands scattered widely over the 
Pacific add weight to this argument. 

North American Earthworks 

The next example is that of the ancient mounds and 
earthworks of the North American continent, the bearing of 
which is even more significant. Over the greater part of the 
extensive Mississippi valley, four well-marked classes of these 
earthworks occur. Some are camps, or works of defence, 
situated on bluffs, promontories, or isolated hills ; others are 
vast inclosures in the plains and lowlands, often of geometric 
forms, and having attached to them roadways or avenues 
often miles in length ; a third are mounds corresponding to 
our tumuli, often seventy to ninety feet high, and some of 
them covering acres of ground ; while a fourth group consists 
of representations of various animals modelled in relief on a 
gigantic scale, and occurring chiefly in an area somewhat to 
the north-west of the other classes, in the plains of Wisconsin. 

The first class — the camps or fortified inclosures — re- 
semble in general features the ancient camps of our own 
islands, but far surpass them in extent. Fort Hill, in Ohio, 
is surrounded by a wall and ditch a mile and a half in length, 
part of the way cut through solid rock. Artificial reservoirs 
for water were made within it, while at one extremity, on a 
more elevated point, a keep is constructed with its separate 
defences and water-reservoirs. Another, called Clark's Work, 
in the Scioto valley, which seems to have been a fortified 
town, incloses an area of 127 acres, the embankments measur- 



426 TROPICAL NATURE Vli 

ing three miles in length, and containing not less than three 
million cubic feet of earth. This area incloses numerous 
sacrificial mounds and symmetrical earthworks, in which 
many interesting relics and works of art have been found. 

The second class — the sacred inclosures — may be compared 
for extent and arrangement with Avebury or Karnak, but 
are in some respects even more remarkable. One of these 
at Newark, Ohio, covers an area of several miles, with its 
connected groups of circles, octagons, squares, ellipses, and 
avenues on a grand scale, and formed by embankments from 
twenty to thirty feet in height. Other similar works occur 
in different parts of Ohio ; and by accurate survey it is, found, 
not only that the circles are true, though some of them are 
one-third of a mile in diameter, but that other figures are 
truly square, each side being over 1000 feet long; and, what 
is still more important, the dimensions of some of these 
geometrical figures, in different parts of the country and 
seventy miles apart, are identical. Now this proves the use, 
by the builders of these works, of some standard measures of 
length ; while the accuracy of the squares, circles, and, in a 
less degree, of the octagonal figures, shows a considerable 
knowledge of rudimentary geometry and some means of 
measuring angles. The difiiculty of drawing such figures on 
a large scale is much greater than any one would imagine 
who has not tried it ; and the accuracy of these is far beyond 
what is necessary to satisfy the eye. We must, therefore, 
impute to the builders the wish to make these figures as 
accurate as possible, and this wish is a greater proof of 
habitual skill and intellectual advancement than even the 
ability to draw such figures. If, then, we take into account 
this ability and this love of geometric truth, and further 
consider the dense population and civil organisation implied 
by the construction of such extensive systematic works, we 
must allow that these ancient people had reached the earlier 
stages of a civilisation of which no traces existed among the 
savage tribes who alone occupied the country when first 
visited by Europeans. 

The animal mounds are of comparatively less importance 
for oui' present purpose, as they imply a somewhat lower 
grade of advancement; but the sepulchral and sacrificial 



VII THE ANTIQUITY AND ORIGIN OF MAN 427 

mounds exist in vast numbers, and their partial exploration 
has yielded a quantity of articles and -works of art which 
throw some further light on the peculiarities of this mysteri- 
ous people. Most of these mounds contain a large concave 
hearth or basin of burnt clay, of perfectly symmetrical form, 
on which are found deposited more or less abundant relics, 
all bearing traces of the action of fire. We are therefore only 
acquainted with such articles as are practically fire-proof, or 
have accidentally escaped combustion. These consist of bone 
and copper implements and ornaments, disks and tubes ; 
pearl, shell, and silver beads, more or less injured by the fire ; 
ornaments cut in mica; ornamental pottery; and numbers 
of elaborate carvings in stone, mostly forming pipes for 
smoking. 1 The metallic articles are all formed by hammer- 
ing, but the execution is very good; plates of mica are 
found cut into scrolls and circles ; the pottery, of which 
very few remains have been found, is far superior to that 
of any of the Indian tribes, since Dr. Wilson is of opinion 
that it must have been formed on a wheel, as it is often of 
uniform thickness throughout (sometimes not more than one- 
sixth of an inch), polished, and ornamented with scrolls and 
figures of birds and flowers in delicate relief. But the most 
instructive objects are the sculptured stone pipes, representing 
not only various easUy recognisable animals, but also human 
heads, so well executed that they appear to be portraits. 
Among the animals, not only are such native forms as the 
panther, bear, otter, wolf, beaver, raccoon, heron, crow, turtle, 
frog, rattlesnake, and many others well represented, but also 
the manatee, which perhaps then ascended the Mississippi as 
it now does the Amazon, and the toucan, which could hardly 
have been obtained nearer than Mexico. The sculptured 
heads are especially remarkable, because they present to us 
the features of an intellectual and civilised people. The nose 
in some is perfectly straight, and neither prominent nor 
dilated ; the mouth is small, and the Hps thin ; the chin and 
upper lip are short, contrasting with the ponderous jaw of 
the modern Indian, while the cheek-bones present no marked 

1 Woven cloth, apparently of flax or hemp, as well as gauges supposed to 
have heen used to regulate the thickness of the thread, have also been found 
in several of the mounds of Ohio (Poster's Prehistoric Races of the United 
States, 1873, pp. 225-229). 



428 TROPICAL NATURE 



prominence. Other examples have the nose somewhat pro- 
jecting at the apex in a manner quite unlike the features of 
any American indigenes ; and although there are some which 
show a much coarser face, it is very difficult to see in any of 
them that close resemblance to the Indian type which these 
sculptures have been said to exhibit. The few authentic 
crania from the mounds present corresponding features, being 
far more symmetrical and better developed in the frontal 
region than those of any American tribes, although somewhat 
resembling them in the occipital outline ; ^ while one was 
described by its discoverer (Mr. W. Marshall Anderson) as a 
" beautiful skull, worthy of a Greek." 

The antiquity of this remarkable race may perhaps not 
be very great as compared with the prehistoric man of Europe, 
although the opinion of some writers on the subject seems 
affected by that " parsimony of time " on which the late Sir 
Charles Lyell so often dilated. The mounds are all over- 
grown with dense forest, and one of the large trees was 
estimated to be 800 years old, while other observers consider 
the forest growth to indicate an age of at least 1000 years. 
But it is well known that it requires several generations of 
trees to pass away before the growth on a deserted clearing 
comes to correspond with that of the surrounding virgin 
forest, while this forest, once established, may go on growing 
for an unknown number of thousands of years. The 800 or 
1000 years estimate from the growth of existing vegetation 
is a minimum which has no bearing whatever on the actual 
age of these mounds ; and we might almost as well attempt 
to determine the time of the glacial epoch from the age of 
the pines or oaks which now grow on the moraines. 

The important thing for us, however, is that when North 
America was first settled by Europeans, the Indian tribes 
inhabiting it had no knowledge or tradition of any preceding 
race of higher civilisation than themselves. Yet we find that 
such a race existed — that they must have been populous and 
have lived under some established government ; while thera 
are signs that they practised agriculture largely, as, indeed, 
they must have done to have supported a population capable 
of executing such gigantic works in such vast profusion ; for 

^ Wilson's Prehistoric Man, 3d ed., vol. ii. pp. 123-130. 



VII THE ANTIQUITY AND ORIGIN OF MAN 429 

it is stated that the mounds and earthworks of various kinds 
in the State of Ohio alone amount to between eleven and 
twelve thousand. In their habits, customs, religion, and arts, 
they differed strikingly from all the Indian tribes; while 
their love of art and of geometric forms, and their capacity 
for executing the latter upon so gigantic a scale, render it 
probable that they were a really civilised people, although the 
form their civilisation took may have been very different from 
that of later peoples, subject to very different influences and 
the inheritors of a longer series of ancestral civilisations. 
We have here, at all events, a striking example of the transi- 
tion, over an extensive country, from comparative civilisation 
to comparative barbarism, the former leaving no tradition and 
hardly any trace of its influence on the latter. 

As Mr. Mott well remarks : " Nothing can be more striking 
than the fact that Easter island and North America both give 
the same testimony as to the origin of the savage life tound 
in them, although in aU circumstances and surroundings the 
two cases are so different. If no stone monuments had been 
constructed in Easter island, or mounds containing a few 
relics saved from fire, in the United States, we might never have 
suspected the existence of these ancient peoples." He argues, 
therefore, that it is very easy for the records of an ancient 
nation's life entirely to perish or to be hidden from observa- 
tion. Even the arts of Nineveh and Babylon were unknown 
only a generation ago, and we have only just discovered the 
facts about the mound-buUders of North America. 

But other parts of the American continent exhibit parallel 
phenomena. Eecent investigations show that in Mexico, 
Central America, and Peru, the existing race of Indians has 
been preceded by a distinct and more civilised race. This 
is proved by the sculptures of the ruined cities of Central 
America, by the more ancient terra -cottas and paintings of 
Mexico, and by the oldest portrait-pottery of Peru. All 
alike show markedly non- Indian features, while they often 
closely resemble modern European types. Ancient crania, 
too, have been found in all these countries, presenting very 
different characters from those of any of the existing indi- 
genous races of America. ^ 

' Wilson's Prehistoric Man, 3d ed., vol. ii. pp. 125, 144. 



430 TROPICAL NATURE 



The Great Pyramid 

There is one other striking example of a higher phase of 
development in science and the arts being succeeded by a 
lower phase, which is in danger of being forgotten because it 
has been made the foundation of theories which seem wild 
and fantastic, and are probably in great part erroneous. I 
allude to the Great Pyramid of Egypt, whose form, dimen- 
sions, structure, and uses have recently been the subject of 
elaborate works by Professor Piazzi Smyth. Now the admitted 
facts about the pyramid are so interesting and so apposite to 
the subject we are considering, that I beg to recall them to 
your attention. Most of you are aware that this pyramid 
has been carefully explored and measured by successive 
Egyptologists, and that the dimensions have lately become 
capable of more accurate determination owing to the discovery 
of some of the original casing-stones, and the clearing away 
of the earth from the corners of the foundation, showing the 
sockets in which the corner-stones fitted. Professor Smyth 
devoted many months of work with the best instruments in 
order to fix the dimensions and angles of all accessible parts 
of the structure : and he has carefully determined these by a 
comparison of his own and all previous measures, the best 
of which agree pretty closely with each other. The results 
arrived at are — 

1. That the pyramid is truly square, the sides being equal 
and the angles right angles. 

2. That the four sockets on which the four first stones of 
the corners rested are truly on the same level. 

3. That the directions of the sides are accurately to the 
four cardinal points. 

4. That the vertical height of the pyramid bears the same 
proportion to its circumference at the base as the radius of a 
circle does to its circumference. 

Now all these measures, angles, and levels are accurate, 
not as an ordinary stirveyor or builder could make them, but 
to such a degree as requires the very best modern instruments 
and all the refinements of geodetical science to discover any 
error at all. In addition to this we have the wonderful per- 
fection of the workmanship in the interior of the pyramid, 



VII THE ANTIQUITY AND ORIGIN OF MAN 431 



the passages and chambers being lined with huge blocks of 
stones fitted with the utmost accuracy, while every part of 
the building exhibits the highest structural science. 

In all these respects this largest pyramid surpasses every 
other in Egypt. Yet it is universally admitted to be the 
oldest, and also the oldest historical building in the world. 

Now these admitted facts about the Great Pyramid are 
surely remarkable and worthy of the deepest consideration. 
They are facts which, in the pregnant words of the late Sir 
John Herschel, "according to received theories ought not 
to happen," and which, he tells us, should therefore be kept 
ever present to our minds, since " they belong to the class of 
facts which serve as the clue to new discoveries." According 
to modern theories, the higher civilisation is ever a growth 
and an outcome from a preceding lower state ; and it is 
inferred that this progress is visible to us throughout all 
history and in all material records of human intellect. But 
here we have a building which marks the very dawn of 
history, which is the oldest authentic monument of man's 
genius and skill, and which, instead of being far inferior, is 
very much superior to all which followed it. Great men are 
the products of their age and country, and the designer and 
constructors of this wonderful monument could never have 
arisen among an unintellectual and half -barbarous people. 
So perfect a work implies many preceding less perfect works 
which have disappeared. It marks the culminating point of 
an ancient civilisation, of the early stages of which we have 
no trace or record whatever. 

Goncl%don 

The three cases to which I have now adverted (and there 
are many others) seem to require for their satisfactory inter- 
pretation a somewhat different view of human progress from 
that which is now generally accepted. Taken in connection 
with the great intellectual power of the ancient Greeks — 
which Mr. Galton believes to have been far above that of the 
average of any modern nation — and the elevation, at once 
intellectual and moral, displayed in the writings of Confucius, 
Zoroaster, and the Vedas, they point to the conclusion that, 
while in material progress there has been a tolerably steady 



432 TROPICAL NATURE 



advance, man's intellectual and moral development reached 
almost its highest level in a very remote past. The lower, 
the more animal, but often the more energetic types have, 
however, always been far the more numerous; hence such 
established societies as have here and there arisen under the 
guidance of higher minds have always been liable to be swept 
away by the incursions of barbarians. Thus in almost every 
part of the globe there may have been a long succession of 
partial civilisations, each in turn succeeded by a period of 
barbarism ; and this view seems supported by the occurrence 
of degraded types of skull along with such " as might have 
belonged to a philosopher," at a time when the mammoth and 
the reindeer inhabited southern France. 

Nor need we fear that there is not time enough for the 
rise and decay of so many successive civilisations as this view 
would imply, for the opinion is now gaining ground among 
geologists that palaeolithic man was really preglacial, and that 
the great gap (marked alike by a change of physical condi- 
tions and of animal Hfe) which in Europe always separates 
him from his neolithic successor, was caused by the coming 
on and passing away of the great ice age. 

If the views now advanced are correct, many, perhaps 
most, of our existing savages are the successors of higher 
races ; and their arts, often showing a wonderful similarity in 
distant continents, may have been derived from a common 
source among more civilised peoples. 



VIII 

THE ANTIQUITY OF MAN IN NOETH AMEEICA^ 

Ancient Shell Mounds — Man Coeval with Extinct Mammalia — Man in the 
Glacial Period — Palaeolithic Implements in North America— The 
Auriferous Gravels of California —Fossil Remains under the Ancient 
Lava Beds — Works of Art in the Auriferous Gravels — Human Re- 
mains in the Auriferous Gravels — Concluding Remarks on the 
Antiquity of Man. 

Over a considerable portion of the northern hemisphere the 
remains of man, or his works, have been found in association 
with bones of the extinct mammalia which characterised the 
Glacial epoch, and no evidence has been obtained that man 
at that time dififered more from modern savages than they 
do among themselves. The facts which prove this antiquity- 
were, when first put forth, doubted, neglected, or violently 
opposed, and it is now admitted that such opposition was 
due to prejudice alone, and in every case led to the rejection 
of important scientific truths. Yet after nearly thirty years' 
experience we find that an exactly similar prejudice prevails, 
even among geologists, against all evidence which carries man 
one little step farther back into pre-Glacial or Pliocene times, 
although if there is any truth whatever in the doctrine of 
evolution as applied to man, and if we are not to adopt the 
exploded idea that the Palaeolithic men were specially created 
just when the flood of ice was passing away, they must have 
had ancestors who must have existed in the Pliocene period, 
if not earlier. Is it then so improbable that some trace of 
man should be discovered at this period, that each particle of 
evidence as it arises must be attacked with all the weapons of 

1 This article appeared in the Kineteenlh Century, Nov. 1887. 
2 P 



43i TROPICAL NATURE Vlll 

doubt, accusation, and ridicule, which for so many years 
crushed down the truth with regard to Palaeolithic man? 
One would think, as Jeremy Bentham said of another matter, 
that it was " wicked or else unwise " to accept any evidence 
for facts which are yet so inherently probable that the entire 
absence of evidence for their existence ought to be felt to be 
the greatest stumbling-block. 

No better illustration of this curious prejudice can be 
given than the way in which some recent discoveries of stone 
implements in deposits of considerable antiquity in India are 
dealt with. These implements are of quartzite, and are of 
undoubtedly human workmanship. They were found in the 
Lower Laterite formation, which is said to have undergone 
great denudation and to be undoubtedly very ancient. Old 
stone circles of a great but unknown antiquity are formed of 
it. It is also stated that the distinction between the Tertiary 
and post-Tertiary is very difficult in India, and the age of 
these Laterite beds cannot be determined either by fossils, 
which are absent, or by superposition. Yet we are informed, 
" The presence of Palaeolithic implements proves that the rock 
is of post-Tertiary origin." ^ Here we have the origin of man 
taken as fixed and certain, so certain that his remains may be 
used to prove the age of a doubtful deposit ! Nor do these 
indications of great antiquity stand alone, for in the Ner- 
budda fluviatile deposits Mr. Hackel has found stone weapons 
in situ along with eleven species of extinct fossil mammalia. 

Believing myself that the existence of man in the Tertiary 
epoch is a certainty, and the discovery of his remains or works 
in deposits of that age to be decidedly probable, I hold it to be 
both wise and scientific to accept all evidence of his existence 
before the Glacial epoch which would be held satisfactory for 
a later period, and when there is any little doubt, to give the 
benefit of the doubt in favour of the find rather than against 
it. I hold further that it is equally sound doctrine to give 
some weight to cumulative evidence ; since, when a thing is 
not improbable in itself, it surely adds much to the argument 
in its favour that facts which tend to prove it come from 
many different and independent sources — from those who are 
quite ignorant of the interest that attaches to their discovery, 

' Manual of the Oeology of India, p. 370. 



vin THE ANTIQUITY OF MAN IN NORTH AMERICA 435 

as well as from trained observers who are fully aware of the 
■ importance of every additional fact and the weight of each 
fresh scrap of evidence. Having by the kindness of Major 
Powell, the able Director of the United States Geological Sur- 
vey, been able to look into the evidence recently obtained 
bearing on this question in the North American continent, I 
believe that a condensed account of it will certainly prove of 
interest to English readers. 

The most certain tests of great antiquity, even though they 
afford us no accurate scale of measurement, are furnished by 
such natural changes as we know occur very slowly. Changes 
in the distribution of animals or plants, modifications of the 
earth's surface, the extinction of some species and the intro- 
duction of others, are of this nature, and they are the more 
valuable because during the entire historical period changes 
of this character are either totally unknown or of very small 
amount. Let us then see what changes of this kind have 
occurred since man inhabited the North American continent. 

Ancient Shell Mounds 

The sheU heaps of the Damariscotta Eiver, in Maine, are re- 
markable for their number and extent. The largest of these 
stretches for about half a mile along the shore, and is often six 
or seven feet, and in one place twenty-five feet, in thickness. 
They consist almost exclusively of oyster shells of remarkable 
size, frequently having a length of eight or ten inches, and some- 
times reaching twelve or fourteen inches. They contain frag- 
ments of bones of edible animals, charcoal, bone implements, and 
some fragments of pottery. The surface is covered to a depth 
of several inches with vegetable mould, and large trees grow on 
them, some more than a century old. The special feature to 
which we now caU attention is "that at the present time 
oysters are only found in very small numbers, too small to 
make it an object to gather them ; and we were credibly in- 
formed that they have not been found in larger quantities 
since the settlement in the neighbourhood. It cannot be sup- 
posed that the immense accumulations now seen on the shores 
of Salt Bay could have been made unless oysters had existed 
in very large numbers in the adjoining waters." ^ Here wa 
1 Second Anwudl Report of Trustees of Peabody Museum, p. 18. 



436 TROPICAL NATURE 



have evidence of an important change in the distribution of a 
species of mollusc since the banks were formed. 

On the St. John's river, Florida, are enormous heaps 
largely composed of two freshwater shells, Ampullaria de- 
pressa andPaludina multiHneata, which cover acres of ground, 
and are often six or eight feet thick. Professor Wyman, 
who explored these heaps, remarks : " It seems incredible to 
one who searches the waters of the St. John's and its lakes at 
the present time, that the two small species of shells above 
mentioned could have been obtained in such vast quantities 
as are seen brought together in these mounds, unless at the 
times of their formation the shells existed more abundantly 
than now, or the collection of them extended through very 
long periods of time. When it is borne in mind that the 
shell heaps afford the only suitable surface for dwellings, 
being most commonly built in swamps, or on lands liable to 
be annually overflowed by the rise of the river, they appear 
to be necessarily the result of the labours of a few living on 
a limited area at one time. At present it would be a very 
difficult matter to bring together in a single day enough of 
these shells for the daily meals of an ordinary family." ^ 

On the Lower Mississippi, at Grand Lake, are shell banks 
of great extent which are now fifteen miles inland ; while Nott 
and Gliddon describe similar banks on the Alabama Eiver fifty 
miles inland, and they believe that Mobile Bay must have 
extended so far at the time the shells were collected. These 
beds are often covered with vegetable mould from one to two 
feet thick, and on this grow large forest trees. Equally indica-' 
tive of long occupation and great antiquity is the enormous 
shell mound at San Pablo, on the bay of San Francisco, which 
is nearly a mile long and half a mile wide, and more than 
twenty feet thick. Numerous Indian skeletons and mummies 
have been found in it, showing that it had been subsequently 
used as a place of burial. Some mounds in Florida have 
growing on them enormous live oaks from thirteen to twenty- 
six feet in circumference at five feet from the ground, some 
of which are estimated to be about 600 years old, indicating 
the minimum age possible for the heaps, but not necessarily 
approaching to their real age. 

' Fifth Armual Eejport of Pedbody Museum, p. 22. 



viii THE ANTIQUITY OF MAN IN NORTH AMERICA 437 

The extensive shell heaps of the Aleutian islands have 
been carefully examined and reported on by Mr. Dall, and are 
found to exhibit some remarkable and probably unique pecu- 
liarities. Complete sections "were made across several of these, 
and they were found to consist of a series of distinct layers, 
each marked by some well -defined characteristics. In the 
upper layers only are there any mammalian remains, and 
these may be divided into three subdivisions. In the upper 
bed there are found seals, walruses, etc., aquatic and land 
birds, the arctic fox and dog, with well-made weapons and 
implements, awls, whetstones, needles, and lamps. In the 
next layer the dog and fox are absent, as are remains of 
large whales ; and in the lower mammalian layer there are 
seals and small cetacea only, but no birds or land animals, 
and the weapons found are ruder. We then come to a con- 
siderable layer in which there are no mammalian remains 
whatever, but only fish-bones and moUuscan shells, with rude 
knives, lance heads, etc. Below this is a bottom deposit con- 
sisting entirely of the shells of echini, and containing no 
weapons, tools, or implements of any kind, except towards 
the surface of the layer, where a few hammer stones are 
found, round pebbles with an indentation on each side for 
the finger and thumb. Echinus' eggs are now eaten raw by 
the Aleuts, and it is the only eatable part of the animal. It 
takes forty or fifty full-sized echini for a meal. Some of the 
heaps cover five acres, and from a careful estimate founded 
on experiments, and taking the probable numbers of a colony 
which could have lived on such a spot, Mr. Dall calculates 
that it would take about 2200 years to form such an accu- 
mulation. A similar estimate applied to the upper layers 
brings the time required for the accumulation of the entire 
series to 3000 years, but that is on the supposition that they 
were formed continuously. This, however, was evidently not 
the case. Each layer indicates a change of inhabitants with 
different habits and in a somewhat different phase of civilisa- 
tion, and each such change may imply the lapse of a long 
period, during which the site was abandoned and no accumu- 
lation went on. These shell heaps may, therefore, carry us 
back to a very remote antiquity. 



TROPICAL NATURE 



Man Coeval with Extinct Mammalia 

We next come to remains of man or his works found in 
association with the bones of extinct mammalia. The great 
mastodon skeleton in the British Museum found by Dr. Koch 
in the Osage valley, Missouri, had stone arrow-heads and 
charcoal found near it, but the fact was at the time received 
with the same incredulity as all other evidences of the anti- 
quity of man. This animal was found at a depth of twenty 
feet, under seven alternate layers of loam, gravel, clay, and 
peat, with a forest of old trees on the surface, and one of the 
arrow-heads lay under the thigh-bone of the mastodon and 
in contact with it. About the same date (1859) Dr. Holmes 
communicated to the Philadelphia Academy of Natural 
Sciences his discovery of fragments of pottery in connection 
with bones of the mastodon and megatherium on the Ashley 
river of South Carolina. 

Such cases as these remove all improbability from the 
celebrated Natchez man, a portion of a human pelvis from 
the loess of the Mississippi, which contains bones of the 
mastodon, megalonyx, horse, bison, and other extinct animals. 
This bone was stated by Sir Charles Lyell "to be quite in 
the same state of preservation and of the same black colour 
as the other fossils." Dr. Joseph Leidy agrees with this 
statement, yet he and Professor C. Gr. Forshey maintain that 
it is "more probable" that the human bone fell down the 
cliff froin some Indian grave near the surface. Sir Charles 
Lyell well remarks that " had the bone belonged to any other . 
recent mammal, such a theory would never have been resorted 
to." The admitted identity of the state of preservation and 
appearance of the human and animal bones is certainly not 
consistent with the view that the one is recent, the other 
ancient j the one artificially buried near the surface, the other 
in a natural deposit thirty feet below the surface. 

Of a similar character to the above is the basket-work mat 
found in a rock-salt deposit fifteen to twenty feet below the 
surface in Petit Anse island, Louisiana, two feet above which 
were fragments of tusks and bones of an elephant. The salt 
is said to be very pure, extending over an area of 5000 acres, 
and the formation of such a deposit requires a considerable 



VIII THE ANTIQUITY OF MAN IN NORTH AMERICA 439 

change of physical conditions from those now existing, and 
thus of itself implies great antiquity.^ 

These indications of the great antiquity of American man 
are now supported by such a mass of evidence of the same 
character that all the improbability supposed at first to 
attach to them has been altogether removed. As an illustra- 
tion of this evidence I need only refer here to the Eeport 
on the Loess of Nebraska, by an experienced geologist, Dr. 
Samuel Aughey, who states that this deposit, which is now 
believed by the best American geologists to be of Glacial 
origin, and which covers enormous areas, contains throughout 
its entire extent many remains of mastodons and elephants, 
and that he himself had found an arrow and a spear-head of 
flint at depths of fifteen and twenty feet in the deposit. One 
of these was thirteen feet below a lumbar vertebra of Elephas 
americanus. 

Man in the Glacial Period 

We now take a decided step backwards in time, to relics 
of human industry within or at the close of the Glacial period 
itself. About twenty years ago a well was sunk through the 
drift at Games, a few miles south of Lake Ontario, and at a 
depth of seventeen feet there were found lying on the solid 
rock three large stones enclosing a space within which were 
about a dozen charred sticks, thus closely resembling the cook- 
ing fires usually made by savages. Mr. G. K. Gilbert, of the 
U.S. Geological Survey, obtained the information from the 
mteUigent farmer who himself found it, and after a close ex- 
amination of the locality and the drift deposit in its relation 
to the adjacent lakes, comes to the conclusion that the hearth 
must have been used "near the end of the second Glacial 
period," and at the time of the separation of Lake Ontario 
from Lake Erie. When Mr. Gilbert gave an account of his 
researches on this matter at the meeting of the Washington 
Anthropological Society, 16th November 1886, two other 
gentlemen reported finds of similar character. Mr. Murdock, 
of the Point Barrow Station, near the extreme north-west 
corner of the continent, in maldng an excavation for an earth 
thermometer, found an Eskimo snow-goggle beneath more 
I Foster's PrehUtorio Races of the United States, p, 58, 



440 TROPICAL NATURE 



than twenty feet of frozen gravel and earth capped by a foot 
of turf. This being near the shores of the Arctic Sea may 
be a comparatively recent beach -formation and of no very 
great antiquity ; but the remaining discovery was more im- 
portant. Mr. W. J. M'Gee, a gentleman who has specially 
studied the Glacial and post-Glacial formations for the U.S. 
Geological Survey, described the finding by himself of a spear- 
head in the quaternary deposits of the Walker Kiver Caiion, 
Nevada. These beds consist of several feet of silt and loose 
material at the top, then a layer of calcareous tufa lying upon 
twenty to thirty feet of white marl, containing remains of 
extinct mammalia, and resting unconformably upon somewhat 
similar beds of earlier date. The spear-head was found with 
its point just projecting from the face of the marl about 
twenty-six feet below the surface. Before removing the im- 
plement, he carefully studied the whole surroundings, and 
finally came to the conclusion that it had been embedded in 
the marl during its formation. The beds were deposited by 
the ancient Lake Lahonton. They have been thoroughly in- 
vestigated by able geologists, and have been referred to the 
close of the Glacial period, or about the same time as the 
hearth described by Mr. Gilbert. The spear-head is three 
and a half inches in length, finely made, and well preserved. 

About a hundred miles north-west of St. Paul, in Central 
Minnesota, a thin deposit has been discovered containing 
numerous quartzite implements. They occur at a depth of 
from twelve to fifteen feet in an old river terrace of modified 
drift, and the deposit marks an ancient land surface on which 
the implements are found, and which must have been de- 
posited at about the close of the last Glacial epoch. ^ Mr. N. 
H. Winchell, State geologist of Minnesota, has found similar 
chips and implements in the upper part of the same deposit ; 
and also human bones in the eastern terrace bluffs at Minne- 
apolis, in a formation of about the same age as the above. 

The same writer reports a still more remarkable discovery 
of a fragment of a human lower jaw in the red clay and 
boulder drift, but resting immediately on the limestone rock. 
This red clay belongs to the first or oldest Glacial period, and 

^ "Vestiges of Glacial Man in Minnesota," by F. E. Babbitt, Proc. of Am. 
Assoc, vol. xxxii. 1883. 



viii THE ANTIQUITY OF MAN IN NORTH AMERICA 441 

we thus have the proofs of man's existence carried back not 
only to the end of the Glacial epoch, but perhaps to its very 
commencement. ^ 

Falceolithic Implements in North America 

We now come to the very interesting discoveries of Dr. 
Charles 0. Abbott, of Trenton, New Jersey. In the ex- 
tensive deposits of gravel in the valley of the Delaware, fresh 
surfaces of which are continually exposed in the cliffs on the 
river's banks, he has found large numbers of rude stone im- 
plements, almost identical in size and general form with the 
well-lmown palaeolithic implements of the valley of the Somme. 
These have been found at depths of from five to over twenty 
feet from the surface, in perfectly undisturbed soil, and that 
they are characteristic of this particular deposit is shown by 
the fact that they are found nowhere else in the same district. 
Large boulders, some of very great size, are found throughout 
the deposit, and in one case Dr. Abbott found a well-chipped 
spear-shaped implement immediately beneath a stone weigh- 
ing at least half a ton. Professor N. S. Shaler, of Cambridge, 
Massachusetts, after examining the locality and himself ob- 
taining some implements in situ, says, "I am disposed to 
consider these deposits as formed in the sea near the foot of 
the retreating ice-sheet when the sub-Glacial rivers were pour- 
ing out the vast quantity of water and waste that clearly were 
released during the breaking up of the great ice- time." Dr. 
Abbott, however, adduces facts which seem to prove that 
some part of the deposit at all events was sub-aerial, for he 
states that the very large boulders often have immediately 
under them a foot or more of soil between the lower surface 
of the stone and the gravel, and that this layer often extends 
some distance laterally, showing that it formed a land surface 
on which the boulders rested, and which was subsequently 
removed by water action, except where thus protected. At 
any rate we may accept Professor Shaler's conclusion : " If 
these remains are really those of man, they prove the exist- 
ence of inter-Glacial man on this part of our shore." That 
the implements are of human workmanship is quite certain, 
and the fact stated by Professor Shaler himself, that " they 
1 Annual Report of the State Oeologist of Minnesota, 1877, p. 60. 



442 TROPICAL NATURE 



are made of a curious granular argillite, the like of which I 
do not know in the place," is an additional proof of it. The 
further fact that the remains of man himself have been dis- 
covered in the same deposit completes the demonstration. 
First a human cranium was found of peculiar characteristics, 
being small, long, and very thick ; then a tooth ; and, lastly, 
a portion of a human under jaw, found at a depth of sixteen 
feet from the surface, near where a fragment of mastodon 
tusk had been found some years before. In recording this 
last discovery the curator of the Peabody Museum remarks : 
" To Dr. Abbott alone belongs the credit of having worked 
out the problem of the antiquity of man on the Atlantic coast," 
so that this gentleman appears to stand in a somewhat similar 
relation to this great question in America as did Boucher de 
Perthes in Europe. His researches are recorded in the first, 
second, and third volumes of the Reports of the Peabody 
Museum. 

The interesting series of researches now briefly recorded 
has led us on step by step through the several stages of the 
quaternary at least as far back as the first great Glacial 
period, thus corresponding to the various epochs of Neolithic 
and Palaeolithic man in Europe, terminating in the Sufiblk 
flints, claimed to be pre -Glacial by Mr. Skertchley, or the 
earliest traces of human occupancy in Kent's Cavern, of 
which Mr. Pengelly states that " he is compelled to believe 
that the earliest men of Kent's Hole were inter-Glacial if not 
pre-Glacial." It now remains to adduce the evidence which 
carries us much farther back, and demonstrates the existence 
of man in Pliocene times. This evidence is derived from the 
works of art and human crania found in the auriferous gravels 
of California, and in order to appreciate duly its weight and 
importance, it is necessary to understand something of the 
physical characteristics of the country and the nature of the 
gravels themselves, with their included fossils, since both 
these factors combine to determine their geological age. 

Tlie Awiferous Gi'avels of California 
The great lateral valleys of the Sierra Nevada are charac- 
terised by enormous beds of gravel, sometimes in thick de- 
posits on the sides or filling up the whole bed of the valley, 



vm THE ANTIQUITY OF MAN IN NORTH AMERICA 443 

at other times forming detached hills or even mountains of 
considerable size. These gravel deposits are often covered 
with a bed of hard basalt or lava, having a generally level 
but very rugged surface, and hence possessing, when isolated, 
a very peculiar form, to which the name " table mountain " 
is often given. These tabular hills are sometimes 1000 or 
even 1500 feet high, and the basaltic capping varies from fifty 
to 200 feet thick. The gravels themselves are frequently 
interstratified with a fine white clay and sometimes with 
layers of basalt. 

Geological exploration of the district clearly exhibits the 
origin of this peculiar conformation of the surface. At some 
remote period the lower lateral valleys of the Sierra Nevada 
became gradually filled with deposits of gravel brought down 
from the higher and steeper valleys; During the time this 
was going on there were numerous volcanic eruptions in the 
higher parts of the range, sending out great showers of ashes, 
which formed the beds now consolidated into pipe-clay or 
cement, while occasional lava streams produced intercalating 
layers of basalt. After this had gone on for a long period, 
and the valleys had in many places been filled up with debris 
to the depth of many hundred feet, there was a final and very 
violent eruption, causing outflows of lava, which ran down 
many of the valleys, filled the river beds, and covered up a 
considerable portion of the gravel deposits. These lava 
streams, some of which may be now traced for a length of 
twenty mUes, of course flowed down the lower or middle 
portion of each valley, so that any part of the gravel remain- 
ing uncovered would be that most remote from the river bed 
towards one or other side of the valley. This gravel, being 
now the lowest ground as well as that most easily denuded, 
would of course be eaten away by the torrents and mark the 
commencement of new river beds, which thenceforth went 
on deepening their channels and forming new valleys which 
undermined and carried away some of the gravel, but always 
left steep slopes and cliffs wherever the lava flow protected 
the surface from the action of the rains. Hence it happens 
that the existing rivers are often in very diff'erent directions 
from the old ones, and sometimes cut across them, and thus 
isolated table mountains have been left rising up out of the 



444 TROPICAL NATURE 



surrounding plain or valley. What was once a single lava 
stream now forms several detached hills, the tops of which 
can be seen to form parts of one gently inclined plane, the 
surface of the original lava flow, now 1000 feet or more 
above the adjacent valleys. The American and Yuba valleys 
have been lowered from 600 to 1500 feet, while the Stanis- 
laus river gorge has cut through one of these basalt-covered 
hills to the depth of 1500 feet. 

While travelling by stage, in the summer of 1887, from 
Stockton to the Yosemite valley, I passed through this very 
district, and was greatly impressed by the indications of 
vast change in the surface of the country since the streams of 
lava flowed down the valleys. In the Stanislaus vaUey the 
numerous " table mountains " were very picturesque, often 
running out into castellated headlands or exhibiting long 
ranges of rugged black cliifs. At one spot the road passed 
through the ancient river-bed, clearly marked by its gravel, 
pebbles, and sand, but now about three or four hundred feet 
above the present river. We also often saw rock surfaces of 
metamorphic slates far above the present river-bed, thus 
proving that the original bed-rocks of the valley, as well as the 
lava and gravels, have been cut away to a considerable depth 
since the epoch of the lava flows. The ranges of " table 
mountains," now separated by deep valleys more than 1000 
feet below them, could easily be seen, by their perfect agree- 
ment of slope and level, to have once formed part of an 
enormous lava stream spread over a continuous surface of 
gravel and rock. 

Fossil Bemains under the Ancient Lam Beds 

These great changes in the physical conditions and in the 
surface features of the country alone imply a great lapse of 
time, but they are enforced and rendered even more apparent 
by the proofs of cha,nge in the flora and fauna afforded by the 
fossils, which occur in some abundance both in the gravels and 
volcanic clays. The animal remains found beneath the basaltic 
cap are very numerous, and are all of extinct species. They 
belong to the genera rhinoceros, elotherium, felis, canis, bos, 
tapirus, hipparion, equus, elephas, mastodon, and auchenia, and 
form an assemblage entirely distinct from those that now 



vni THE ANTIQUITY OF MAN IN NORTH AMERICA 445 



inhabit any part of the North American continent. Besides 
these we have a tolerably abundant series of vegetable remains, 
•well preserved in the white clays formed from the volcanic 
ash. These comprise forty-nine species of deciduous trees and 
shrubs, all distinct from those now living, while not a single 
coniferous leaf or fruit has been found, although pines and firs 
are now the prevalent trees all over the sierra. Professor 
Lesquereaux, who has described these plants, considers them 
to be of Pliocene age with some affinities to Miocene ; while 
Professor Whitney, the State geologist of California, considers 
that the animal remains indicate at least a similar antiquity. 

These abundant animal and vegetable remains have mostly 
been discovered in the process of gold-mining, the gravel and 
sand of the old river-beds preserved under the various flows 
of basalt being especially rich in gold. Numerous shafts have 
been sunk and underground tunnels excavated in the auriferous 
gravels and clays, and the result has been the discovery not 
only of extinct animals and plants, but of works of art and 
human remains. The former have been found in nine diiFerent 
counties in the same gravels in which the extinct animals 
occur, while in no less than five widely separate localities, 
underneath the ancient lava flows, remains of man himself 
have been discovered. In order to show the amount of this 
evidence, and to enable us to appreciate the force or weakness 
of the objections with which, as usual, it has been received, a 
brief enumeration of these discoveries will be made. We will 
begin with the works of art as being the most numerous. 

Works of Art in the Auriferous Gravels 

In Tuolumne County from 1862 to 1865 stone mortars 
and platters were found in the auriferous gravel along with 
bones and teeth of mastodon ninety feet below the surface, 
and a stone muller was obtained in a tunnel driven under 
Table Mountain. In 1870 a stone mortar was found at a 
depth of sixty feet in gravel under clay and " cement," as the 
hard clay with vegetable remains (the old volcanic ash) is 
called by the miners. In Calaveras County from 1860 to 
1869 many mortars and other stone implements were found 
in the gravels under lava beds, and in other auriferous gravels 
and clays at a depth of 150 feet. In Amador County stone 



446 TROPICAL NATURE 



mortars have been found in similar gravel at a depth of forty 
feet. In Placer County stone platters and dishes have been 
found in auriferous gravels from ten to twenty feet below the 
surface. In Nevada County stone mortars and ground discs 
have been found from fifteen to thirty feet deep in the gravel. 
In Butte County similar mortars and pestles have been found 
in the lower gravel beneath lava beds and auriferous gravel ; 
and many other similar finds have been recorded. It must 
be noted that the objects found are almost characteristic of 
California, where they are very abundant in graves or on the 
sites of old settlements, having been used to pound up acorns, 
which formed an important part of the food of the Indians. 
They occur literally by hundreds, and are so common that 
they have little value. It seems therefore absurd to suppose 
that in scores of cases, over a wide area of country and over 
a long series of years, gold-miners should have taken the 
trouble to carry down into their mines or mix with their 
refuse gravel these articles, of whose special scientific interest 
in the places where found they have no knowledge whatever. 
It is further noted that many of these utensils found in the 
old gravels are coarse and rudely finished as compared with 
those of more recent manufacture found on the surface. The 
further objection has been made that there is too great a 
similarity between these objects and those made in com- 
paratively recent times. But the same may be said of the 
most ancient arrow and spear heads and those made by 
modern Indians. The use of the articles has in both cases 
been continuous, and the objects themselves are so necessary » 
and so comparatively simple, that there is no room for any 
great modification of form. 

Human Remains in the Amiferous Gravels 

We will now pass on to the remains of man himself. In 
the year 1857 a fragment of a human skull with mastodon 
debris was brought up from a shaft in Table Mountain, 
Tuolumne County, from a depth of 180 feet below the surface. 
The matter was investigated by Professor Whitney, the State 
geologist, who was satisfied that the specimen had been found 
in the " pay gravel," beneath a bed three feet thick of cement 
with fossil leaves and branches, over which was seventy feet 



vm THE ANTIQUITY OF MAN IN NORTH AllERICA 447 

of clay and gravel. The most remarkable discovery, however, 
is that known as the Calaveras skull. In the year 1866 some 
miners found in the cement, in close proximity to a pe