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PLATE I

GROUP OF YOUNG PRIMATES

Behind the table, from left to right are a Chimpanzee,

Asiatic human type (Samoyede), European human type,

and two Orang-utans. In the foreground, to the left a
Gorilla, to the right African human type (Nigerian).
THE CHILDHOOD OF
ANIMALS

BY

P. CHALMERS MITCHELL

M.A., LL.D., D.Sc., F.R.S.

ILLUSTRATED WITH TWELVE COLOURED PLATES FROM PAINTINGS
BY E. YARROW JONES, M.A., AND WITH MANY FIGURES
IN THE TEXT FROM PENCIL DRAWINGS
BY R. B. BROOK-GREAVES

 

NEW YORK

FREDERICK A. STOKES COMPANY
PUBLISHERS
Prais’d be the fathomless universe,
For life and joy, and for objects and knowledge curious.

Watt WHITMAN.

J’ai l'amour de la raison, je n’en ai pas le fanatisme.
ANATOLE FRANCE.

Then sing, ye Birds, sing, sing a joyous song !
And let the young Lambs bound
As to the tabor’s sound !

We in thought will join your throng,
Ye that pipe and ye that play,
Ye that through your hearts to-day
Feel the gladness of the May!

W. Worpswortu.
PREFACE

In December and January of 1911-1912 I delivered the Christmas
Course of Lectures, ‘adapted to a Juvenile Auditory,” at the
Royal Institution of Great Britain, and took as my subject “ The
Childhood of Animals.” The six lectures were not written; they
shaped themselves as the course proceeded, partly in relation to
the set of lantern-slides, specimens and living animals that I was
able to bring, and partly in accordance with the advice of my kind
and experienced friend Sir James Dewar. This book is not a
printed version of the lectures, although it tells the same story in a
different fashion. A lecture must be as direct and as little cumbered
with detail as may be; the leaves of a book can be turned back-
wards and forwards, and its lines skipped or re-read. I have
therefore been able to include many details that I had to omit when
I was speaking, and to cover my canvas in a different way. In
particular, I am no longer trying to address a juvenile auditory ;
I have attempted to avoid the use of terms familiar only to students
of zoology, and to refrain from anatomical detail, but at the same
time to refrain from the irritating habit of assuming that my readers
have no knowledge, no dictionaries and no other books.

My object has been to bring together observations old and new that
seemed to throw a light on the nature of the period in the life-history
of animals between birth and maturity, rather than to write a formal
treatise on the subject. I have not found it possible, nor have I
tried to keep strictly within the logical confines of the title. Where
the subject seemed to lead, there I have followed cheerfully,
remembering that I am not preparing readers for an examina-
tion where no marks will be assigned to extraneous matter.

It has been pleasant to collect the material, pleasanter when it
seemed possible to arrange it so as to display a rational interpreta-
tion, perhaps most pleasant when the unruly facts refused to
conform with theory. Although it may be true, as Lord Morley
once wrote, that the universe will never cease to be “a sovereign

wonder of superhuman fixedness of law,” it is at least a mitigating
vii
PREFACE

In December and January of 1911-1912 I delivered the Christmas
Course of Lectures, ‘‘ adapted to a Juvenile Auditory,” at the
Royal Institution of Great Britain, and took as my subject “ The
Childhood of Animals.” The six lectures were not written; they
shaped themselves as the course proceeded, partly in relation to
the set of lantern-slides, specimens and living animals that I was
able to bring, and partly in accordance with the advice of my kind
and experienced friend Sir James Dewar. This book is not a
printed version of the lectures, although it tells the same story in a
different fashion. A lecture must be as direct and as little cumbered
with detail as may be; the leaves of a book can be turned back-
wards and forwards, and its lines skipped or re-read. I have
therefore been able to include many details that I had to omit when
I was speaking, and to cover my canvas in a different way. In
particular, I am no longer trying to address a juvenile auditory ;
I have attempted to avoid the use of terms familiar only to students
of zoology, and to refrain from anatomical detail, but at the same
time to refrain from the irritating habit of assuming that my readers
have no knowledge, no dictionaries and no other books.

My object has been to bring together observations old and new that
seemed to throw a light on the nature of the period in the life-history
of animals between birth and maturity, rather than to write a formal
treatise on the subject. I have not found it possible, nor have I
tried to keep strictly within the logical confines of the title. Where
the subject seemed to lead, there I have followed cheerfully,
remembering that I am not preparing readers for an examina-
tion where no marks will be assigned to extraneous matter.

It has been pleasant to collect the material, pleasanter when it
seemed possible to arrange it so as to display a rational interpreta-
tion, perhaps most pleasant when the unruly facts refused to
conform with theory. Although it may be true, as Lord Morley
once wrote, that the universe will never cease to be “a sovereign

wonder of superhuman fixedness of law,” it is at least a mitigating
vii
Vili PREFACE

circumstance that as the laws are superhuman, we need not be.
quite certain that we know them. Pleasure in her ways, rather than
a cold comprehension of them, is Nature’s surest gift to us, and Iam
content if I have provided a setting of theory sufficient to make the
facts lustrous.

I am deeply indebted to Mr. E. Yarrow Jones, who prepared the
beautiful designs, painted on Japanese silk, which have been
reproduced as the plates in this volume. I was anxious to obtain
the co-operation of an artist who would see the animals with his
own eyes, adopt his own decorative formula, and not be content
with setting down diagrams giving the data of colour and form that
we find useful in treatises on systematic zoology. IY confess that
my delight was tinged with surprise when I found Mr. Jones’s
art revealed individual and specific characters which cannot be
described by words and diagrams. I have also to offer my sincere
thanks to Mr. R. B. Brook-Greaves for his patience and skill in
making the pencil-drawings for the text-figures.

Finally I have to state my indebtedness, in general terms, to the
great army of writers on zoological subjects. To have tried to
attribute to its proper source each observation that I have used,
or each little piece of half-remembered theory, would have over-
weighted this book with historical pomp, and puffed out its slight
figure to unhealthy repletion. Although there are some observations
that are new, I claim credit for the mode of presentation rather than,
for what is presented.

P. CHALMERS MITCHELL

Lonpon, August 21, 1912
CHAPTER

IT.

III.

IV.

Vv
VI.
VII.
VIII.
IX.

XI.
XII.
XIII.
XIV.
XV.

CONTENTS

PREFACE

. CHILDHOOD AND YOUTH

LARVZ AND METAMORPHOSES

THE DuRATION OF YOUTH IN MAMMALS

Tue DuraTION oF YOUTH IN BirDs aND LOWER ANIMALS
COLOUR AND PATTERN IN ANIMALS

CoLouRS AND PATTERNS OF YouNG MAMMALS

CoLoURS AND PaTTERNS oF YOUNG BIRDS

LIMITATION OF FAMILIES

BROOD-CARE AND LIMITATION OF FAMILIES IN LOWER
VERTEBRATES

. BROOD-CARE IN BIRDS

BROOD-CARE AMONG MAMMALS
Tue Foop oF YounG ANIMALS
Tue TAMING oF YounGc ANIMALS
Tue PurRPOsE oF YOUTH
EpucATION

I Dex

ix

PAGE
vii

17
37
49
62
81
97
115

134
147
163
183
204
222
239
257
I.
II.
ITT.
Iv.
Vv.
VI.

Vil.

VIII.
IX.

Xx.

XI
XII.

LIST OF PLATES

Group of Young Primates

Giraffes and Young

Lion, Lioness and Cub

Lady Amherst’s Pheasants : Cock, Hen and Chicks
Red Deer: Stag, Hinds and Fawn
American Tapir and Young

King Penguins and Young

Sea-gulls and Young

Female Capped Langur Monkey and Young
Female Black-headed Lemur and Young
Black-necked Swans with Cygnets
Springbuck and Young

Frontispiece

To face

PAGE

Io
62
68
92
94

104

162

164

166

240

250
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® wb HH KH HD NY HD WN YD BH HH HH HH HW
SSRSAARS SF GFGC HON AKUARHHHO

LIST OF ILLUSTRATIONS

. Part of the marsupial pouch of the Red Kangaroo, with

young attached

. Reproduction of Ameeba

. Head of an unborn Gorilla

. Head of a Human Feetus

. Head of an unborn long-nosed Ape

. Young cub of American Timber-wolf

. Three stages in the growth of Takin’s horns
. Tadpole of a Frog

. Metamorphosis of an Ascidian

. Metamorphosis of the Sole

. Larve of a Starfish

. Metamorphosis of Polygordius

. Larve of a Gastropod Mollusc

. Larve of the crustacean Penaeus

. Larva and Pupa of Blow-fly

. Caterpillar and chrysalid of Privet Hawk-moth
. Larve and Pupa of the Oil-beetle

. Development of a Locust

. Metamorphosis of Mexican Axolotl

. Repetition Pattern

. Bilateral Ink Pattern

. Oyster-catcher

. Young and Adult Banded Duiker Antelope
. Young and Adult Selous’ Sitatunga Antelope
. Down-plumage Patterns

. Sea-urchin carrying its young

. Brittle-star carrying its young

. Male Hippocampus, showing brood-pouch

. Darwin’s Rhinoderma, showing brood-pouch
. Ring-tailed Lemur carrying its young

xiii

PAGE

Oo Oo ON WwW

10
13

20
22
23
25
26
29
31

32
33
35

64
65
79
89
go
107
119
120
137
I4I
167
X1V LIST OF ILLUSTRATIONS

31.
32.
33-
34-
35-
36.

Hippopotamus carrying its young
Tree-hyrax carrying its young
Tree-kangaroo with young in pouch
Koala carrying its young

Opossum carrying its young

Brains of Primates

PAGE
172
174
179
181
181

227
CHAPTER I
CHILDHOOD AND YOUTH

WE look out on the world with human eyes, and see with little
wonder whatsoever is like ourselves. We are born, small and
helpless, yet visibly stamped with humanity; day by day we
change, but move with certainty in one direction. A few years
pass, and from childhood we attain youth, a few more and we
reach maturity. The changes affect size and structure, character
and disposition, but are so orderly and familiar that we accept
them without surprise, and demand for them no explanation. Man
is only one of many hundreds of thousands of living species, and
living beings are only a small part of the world around us. Is the
mode by which man attains manhood universal in the living world,
and does the living world differ in this respect from things that are
not alive ?

The universe throbs with restless change. Oursun with its system
of revolving planets is rushing into the recesses of starry space on
some errand at which we cannot guess. The little planet that is the
home of the only life we know is impermanent in its masses and
in its details. The oceans shift on their uneasy beds ; continents
and islands rise and fall. Mountains and plains are carved and
fretted by air and wind and water, blistered by heat, riven by
frost, and smoothed over by vegetation. The chemical elements of
which we used to think as eternal counters, passing unchanged
through mazes of combination and disintegration, are, some of them
at least, in a process of making or unmaking. Everything that
we know is @ecoming rather than being. None the less there are
degrees and differences in change itself. The swift and inevitable
routine of life stands in sharp contrast with the vaguer and more
capricious rhythms of things that are not alive. All living creatures
are born into the world from seeds or eggs or directly from the
bodies of their parents, and unless they meet death by the way, meet
it at the end, after passing through childhood and youth, maturity
and old age. This orderly progress from the beginning to the end is

C.A. A
2 CHILDHOOD OF ANIMALS

characteristic of all animals, and the parts of it that we call childhood
and youth are the most characteristic. Complicated pieces of
machinery, like watches or motor-cars, resemble animals in many
ways, and like them may be new or old, but are never young.
Youth is a property of the living world.

The history of an animal, from its first appearance as a speck
of living matter formed from the parental body, to its death, is
continuous, and it would be useless to try to define exactly when
childhood begins, when it passes into youth, or the point at which
the period of youth ends. There is difficulty even in fixing the
beginning, for animals of the same kind may be born at different
stages of growth, whilst animals of different kinds differ extremely
in this respect. A large black newt, brilliantly spotted with yellow,
known as the spotted salamander and common in the south of
Europe, lays eggs like the spawn ofa frog. But unlike the eggs of the
frog which show the presence of tadpoles only after some days, those
of the salamander appear with fully formed little tadpoles wriggling
in them, and hatch almost as soon as they are laid. Sometimes
they hatch actually before they are laid, and it is in the tadpole
stage that the animals first appear in the world. So also most
snakes lay eggs and incubate them for days or weeks, before
the young snakes break through the leathery shell. But in some
snakes, like the common adder, what corresponds to hatching takes
place inside the body of the mother, and instead of eggs being laid,
young snakes are born. Most of the warm-blooded, hairy creatures
that we know as mammals because they suckle their young, give
birth to moving young and do not lay eggs, but two of them, the
duck-billed platypus and the spiny echidna of Australia, lay eggs
with yolk and hard shells. The platypus incubates the eggs until
they hatch; the echidna, after laying an egg, transfers 1t with her
mouth to a pouch on the under side of her body, like that of a
kangaroo, and in this warm and secure receptacle, safer than any
nest, the egg is kept until it hatches. Mammals of the group
known as Marsupials, because most of them have a marsupium, or
pouch (which is well seen in the kangaroo), at one time laid large
eggs and no doubt transferred them with the mouth to the pouch, just
as the echidna still does. But now the eggs are retained for a certain
time in the body, although the young are still very imperfect when
they are born. The new-born young of a kangaroo is less than an
inch long, although its mother may be nearly as tallas a man. The
figure (Fig. 1) has been drawn from a specimen obtained at the
CHILDHOOD AND YOUTH 3

London Zoological Gardens, and shows the naked little creature, an
embryo rather than a young animal, hanging to a nipple inside
the hairy pouch of its mother. In higher mammals eggs are not
laid, and the young at birth are much more formed than in the case
of the kangaroo, but they may be covered with fur, have their eyes
open and be able to run in a few minutes, like young hares, or, like
young rabbits, may be naked, blind and helpless. Even in one
species there may be notable differences ; the kittens in a single
litter are seldom alike in size, in the degree of their development and
in the date when they
begin to see, and
although new - born
human babies are
more closely similar,
some may be at least
a month older or a
month younger than
usual, and yet grow
up quite normally.
These differences are
interesting and im-
portant, but I men-
tion them here only
to show that there is

no exact, fixed point Fic. 1. Part of the inner wall of the pouch of the red
in its history when kangaroo, with the young attached to the teat.

ey aekas (Natural size.)
a new individual
ceases to be an egg or an embryo and may fairly be called a young
animal.

In the same way the end of the period of youth is indefinite. Some-
times there is a sharp break. Accaterpillar becomes a chrysalid and
from the chrysalid the full-grown moth or butterfly emerges. Some-
times, perhaps more often, the transition is gradual. Even the time
when a young animal itself can become a parent does not give adividing
line. A few generations ago, girls were thought fitted for marriage
when they were fourteen, and not infrequently became mothers
whilst they were still children. Amongst animals, parentage is
often precocious in individuals or in whole groups. We must be
content to take the period of youth in a general way as a subject
for description rather than for precise definition.

Young animals can be placed in three groups, notably different in

  
4 CHILDHOOD OF ANIMALS

their character. The first group has little claim to existence ; it
contains a few animals that have no period of youth. The second
group contains very many of the animals with which we are most
familiar. The young are sufficiently like their parents to enable us
to make a close guess as to what they are going to become. We
have no doubt that a human baby is a young human being, that a
baby monkey belongs to the group of monkeys, although we may
not be quite certain as to the particular species of which it is a
member. It is the same with kittens, puppies, calves and lambs ;
we place them at once among the mammals, with complete certainty
in their own order, and with a probability that depends on our
powers of observation and knowledge in their proper family, genus,
or species. Young birds may puzzle us a little more, but at the
least we are never in doubt that the naked or fluffy creatures are
going to be birds. Crocodiles and lizards, snakes and turtles
similarly come into the world with their relationships plainly stamped
upon them,

In the third group we must place those young animals, of which
many insects and marine creatures are familiar types, that are
so unlike their parents that their destiny cannot be guessed from
inspection. The changes through which many of these creatures
pass on their way to adult life are as strange as if a new-born
human baby were to have the form of a fish, swimming in a tank,
feeding greedily on worms and water-fleas, and then after a few
weeks or months were to grow very fat and sleepy, to split along
the back, and, discarding its fish-skin, to creep out on land in the form
of a hedgehog ; and if the hedgehog were to live for months or years
the life of a humble quadruped, growing bigger and fatter until it
too reached a limit of growth, broke out of its hedgehog skin and
appeared as an adult human being fitted in body and mind to be a
bishop or a burglar.

It is not to be supposed that these three different kinds or aspects
of youth agree with the divisions in which the animal kingdom is
atranged by zoologists. It happens that the creatures without
a true period of youth belong to the lowest division of animals, and
that the highest animals fall naturally into the second group, but
the vast range of living beings between the lowest and the highest
divisions show all degrees of close likeness and complete unlikeness
to their parents. Nor must it be supposed that the three groups are
sharply marked off. The arrangement of facts in groups is more
convenient than natural, and we must not forget that many of the
CHILDHOOD AND YOUTH 5

divisions of science are concessions to the human mind rather than
forms of nature.

Further consideration of the first group need not detain us
long. The very small animals known as amcebe (Fig. 2), the
largest of which are visible as specks to the naked eye, are mere
droplets of granular protoplasm, creeping over the mud in fresh

 

Fic. 2. Reproduction of Amceba (highly magnified). To the left a full-grown
amceba ; to the right successive stages of division.

water or in the sea, or lurking in the bodies of other animals or of
plants. The soft, jelly-like material of which they are formed
makes it possible for little particles of food to be engulfed wherever
these come in contact with the surface of the body. The simple
business of their life is to creep in search of food, to digest the food
as quickly as possible, and to grow bigger. But although the
different kinds of ameceba differ in size, there is a limit beyond
which each kind does not grow. When that limit has been reached,
or sometimes before it has been reached—for reproduction is a good
deal more complicated in its causes than a mere escape from incon-
6 CHILDHOOD OF ANIMALS

venient size—the amceba becomes oblong in shape and then acquires
a kind of waist which becomes more and more slender until only a
string of jelly remains. Finally this string divides, and the two
halves become rounded again, each forming a complete amceba,
exactly like the parent in all respects except size, and these two
at once set about the pursuit of food and begin to grow. The
two amcebe may be called young animals in the sense that they
have just come into existence as new individuals, but nothing in
their tissues or characters distinguishes them from their parent. So
far as the period of youth has any interest or significance, these
animals escape it. Many small creatures belonging to the lowest
group of the animal kingdom, the Grade known as Protozoa, repro-
duce like amceba by a process of simple division, and it is tempting
to suppose that this method is older than the more complicated
fashions in which most animals multiply. Even amongst Protozoa,
however, very many animals begin their individual lives in a form
unlike that of their parents, and attain the adult condition only
after passing through complicated changes. I am not going to
describe any of these here, as they show no characters of youth
that are not equally well displayed in animals easier to observe. I
wish to recall their existence, however, because it is very frequently
the case in the living world that simple structures and events are
not primitive, and it may well be that the Protozoa without a true
period of youth are not surviving relics of primeval life, but are
forms that have become simple and degenerate because of the easy
conditions in which they live.

The animals in the second group will engage most of our atten-
tion in this book, because they include ourselves and those most
nearly akin to us. As their structures, habits, and dispositions
are not very remote from our own, they offer problems which it is
possible to understand, and perhaps to solve, and they give a hope
of interpreting our own history and of predicting, perhaps controlling,
our own future. They have this in common, that the young always
resemble the parents more or less closely.

Amongst human beings and monkeys, the young are born in so
advanced a condition that we think of them as babies and not as
embryos. The eyes are open, the voice is lusty, the face, the hands
and feet, and the body generally are shapely and well formed. But
the senses are deficient, especially in the great apes and man. The
hand of a new-born infant will close round and cling to a broom-
stick or any other object placed in it, almost in the automatic
CHILDHOOD AND YOUTH 7

fashion in which the tendril of a creeper will twine round a support
which it comes to touch. So also, in the danger of the woods, the
new-born gorilla or chimpanzee must cling from the first to the body
of its mother, or perish miserably. In a few days the observing
and reflecting parts of the brain awaken, automatic action becomes
less important, and is replaced by a medley of instinct and intelligence.
In the lower monkeys, and especially in lemurs, although the young
cling to their mothers, the automatic period is shorter, and the
babies, almost from the first, show what looks like conscious,
independent movement. Human babies and the babies of apes
and monkeys differ from their parents in proportions. The heads
are relatively larger, especially in the higher creatures, and the
legs and arms are relatively shorter. They all, as a rule, are born
with some hair, but this is more scanty and more different in texture
and colour than that of the parents in human beings and the great
apes, more like that of the parents, in abundance, texture and colour,
in the lower monkeys and lemurs. Special growths of hair, like
beards and crests, special patches of colour on the face and body,
like the brilliant scarlet and blue on the face of the mandrill, are
absent. I need not waste time recalling familiar differences like
the absence of teeth, and of bony ridges on the head, the softness of
the bones, the protruding stomachs and the general plumpness and
roundness of the body.

I have already said of this group of young animals that although
there is a fairly close resemblance with the parents, we cannot
always be certain of the particular species to which an infant
belongs. The reason of this difficulty lies in the striking circum-
stance that the young of nearly allied animals are much more alike
than are the adults. No one could fail to distinguish a fully
grown man, gorilla, orang and chimpanzee, but in many points in
which the young of these creatures differ from the adults, they
resemble each other more closely. In the slow development of
every individual before birth and after birth, the characters of the
species are the last to be assumed. We explain this by supposing
that the evolution of the individual to a certain extent repeats the
evolution of the race. Man, the gorilla, the orang and the chim-
panzee had a common ancestor, and the children of these creatures
are more like the common ancestor, and so like each other, than are
the adults. We have to remember, however, that this explanation
is not complete, and we shall find many characters of young animals
to which it does not apply. The young animal owes its characters
8 CHILDHOOD OF ANIMALS

not merely to its ancestry ; as much as the adult, it has to be fitted
to the special environment in which it lives. It is not merely a stage
in development, but an independent living creature with its own
needs and its own aptitudes, presenting characters that are neither a
memory nor an anticipation, neither a relic of the past nor a pre-
paration for the future, but suitable for its own purposes. These

 

Fic. 3. Head of an unborn gorilla. (After J. DENIKER.)

creatures, suckling their mothers, clinging to them and being pro-
tected by them, have an environment which is much simpler and
more nearly identical than the environment of the adults, and we
must expect, quite apart from common inheritance, to find common
characters due to common conditions. The figures on the first
coloured plate (see Frontispiece) represent young animals two or three
years old, and show how much more alike they are when they are
still children than when they are grownup. The young gorilla, with
its small ears and short upper lip, is not very different in appear-
ance from a black baby ; the very long upper lips of the orang and
CHILDHOOD AND YOUTH 9

chimpanzee and the large ears of the latter make them rather less
human.

The parental stages of man and the great apes are still more alike
than are the young creatures. The text-figures of the young
gorilla (Fig. 3), taken from a specimen of an unborn ape obtained
by Monsieur J. Deniker, and of a human being of about the same
age, after a figure given by Professor Metchnikoff (Fig. 4), show the
almost appalling resemblance between man and the ape before birth.

   

Fic. 4. Head of a human foetus, about Fic. 5. Head of an unborn long-
five months old. (Aftey E. METcHNIKOFF.) nosed ape. (After E. SELENKa.)

For comparison, I have given in another figure (Fig. 5) a representa-
tion of a corresponding stage in the development of one of the lower
monkeys, the long-nosed ape of Borneo, taken from a drawing given
by Professor Selenka in his great monograph on the embryology of
mammals. The face and features, the domed forehead covering the
capacious brain, the practical absence of hair, and every minute
detail of the internal and external structure agree with a fidelity that
is almost shocking. Professor Metchnikoff was so impressed by
such resemblances that he has suggested that the human race may
have taken its origin from the precocious birth of an ape. His
theory may be regarded rather as a parable than a definite scientific
proposition, but it puts in a striking fashion a remarkable character
displayed by young animals. When these differ from the adults,
it is not merely that they resemble their ancestors, or are specially
ro CHILDHOOD OF ANIMALS

fitted for the purpose of their own stage of life. They sometimes
suggest the future possibilities of the race, directions in which the
race may move. As the young animals mature they lose promise
and flexibility, and settle down to the average characters and average
limitations of their kind.

Young Carnivores seldom differ notably from their parents. The
cubs of lions, tigers, leopards and jaguars, and the kittens of cats,
lynxes and caracals can usually be identified at a glance. They

   

Fic. 6. Young American timber-wolf,
are softer and more rounded, and differ in size and in proportions, and
they do not display characters limited to one sex, like the mane of
the lion, or special marks like the twisted, hairy tufts on the tips
of the ears of caracals and lynxes, and those which are uniformly
coloured when they are adult may be spotted when they are young.
The puppies or cubs of dogs, dingoes, wolves, jackals and foxes are
much more alike than the adults, and point clearly to descent from
a common and not very distant ancestor. Young wolves (the
‘drawing in Fig. 6 represents the cub of an American timber-wolf) are
quite like the puppies of domestic dogs, except that their ears are
erect. The difference is mental rather than physical. When they
begin to run about, they betray a shy and furtive disposition, as if
they expected no kindness or toleration from man. Young hyenas
and civets, bears, raccoons and weasels, seals and sea-lions all closely
resemble their parents.
PLATE IT
GIRAFFES AND YOUNG

The colorations of the young and the adult are practically
identical, but the neck and forequarters of the young are
relatively shorter. By an accident of the drawing, the
vertical rails in the background make the necks of the
adults appear rather shorter than they are, but the pro-
portions are correct by measurement.
e
 
CHILDHOOD AND YOUTH Tr

It would be tedious to go through mammals group by group,
making the same general statements about them. Differences of
colour and pattern in the coat are often remarkable and will be
discussed in a separate chapter (Chapter VI). When the adults have
no special weapons or ornaments, they can be distinguished from
their young by little that is visible, except size. A young hippo-
potamus, except for the absence of tusks, a young dromedary or
bactrian camel, except that the humps are not so conspicuous, and
a kangaroo, as soon as it is able to leave the pouch of its mother,
are almost ludicrously exact miniatures of their parents. Baby
elephants are more interesting. The smallest that I have seen
was a female Indian elephant, presented to the London Zoological
Gardens by the Government of the Federated Malay States, and
certainly less than a year old and about three feet in height. No
one could mistake it for anything but an elephant, but it was
thickly covered with long coarse hair, recalling its distant relative,
the extinct hairy mammoth. Its ears were much larger in propor-
tion to the size of the head than in the adult Indian elephant, so
recalling the African animal, and this resemblance was increased
by the smoothly rounded forehead, passing in an even curve from
the root of the trunk to the top of the head, and showing no sign of
the angular forehead of adult Indian elephants. Its trunk was
rather short, the tip being well off the ground when the little animal
was standing upright, and was rather an embarrassment to it. It
found difficulty in finding its mouth with it, fumbling as a baby does
when trying touseaspoon. Nor had it learned to use it in drinking ;
it sucked its milk by a rubber tube placed in its mouth, holding its
trunk awkwardly out of the way. No doubt if we could see together
a young Indian elephant, a young African elephant and a young
mammoth, we should find that they were as much alike as are the
young of the great apes and man.

A young giraffe (see Plate II) from the first resembles its parents,
but neither its neck nor its legs are so long in proportion, and the
horns, although erect and tufted with hair like those of the adult,
are soft because they have no bony core. In the great assemblage
of animals that are armed with horns or antlers the peculiarities of
these weapons appear gradually, and the young, at first defenceless,
produce little straight spikes like those of their fossil ancestors, and
these, as they grow larger, curve or twist or branch until they reach
the full splendour of maturity. In antelopes, sheep, goats and
cattle, where the horns are “hollow,” that is to say, where they
12 CHILDHOOD OF ANIMALS

consist of a horny case fitting over a bony core, the first weapons
to appear persist throughout life, however they may increase in
size and change in shape. In Fig. 7 some of these differences are
shown. The takin, a rare and very large goat-like animal from the
highlands of Asia, shows little conical horns when it is a few months
old. These are placed rather far apart on the forehead, separated
by an expanse of hair. As the horns grow they acquire a spiral,
goat-like twist and the greatly expanded lower portions meet in the
middle line to form a stout rough helmet. In the eland, one of
the largest of the African antelopes, the horns first appear as still
more slender conical spikes, and as they grow usually become twisted
in a straight spiral in the fashion in which a stick of soft candy can
be twisted when one end is held firm and the other rotated. Cattle of
different kinds also show small spiky horns at first, and these later
on acquire the spreading curves of the adult.

The change in the kinds of horns we know as antlers, and which
are found amongst deer, are even more interesting. Antlers are
shed and renewed annually, and except in the reindeer are carried
only by the males. In young male fawns, a pair of bosses, covered
by the hairy skin and consisting of outgrowths of the bones of
the skull on the forehead above the eyes, appear very soon. Early
in the first season a bony knob is formed on the summit of each
boss and can be felt as a warm and tender swelling. It grows
very quickly and in a few weeks each has become a short spike still
covered with the layer of skin which contains many blood-vessels
and is known as the velvet, because of its soft and hairy surface.
When the growth is nearly complete, a ring of bone is formed
under the velvet, near the base of the antler, and by its pressure stops
the circulation of blood in the skin. The velvet then peels off, the
deer assisting in the process by rubbing the antlers against the bark
of trees, and when the bloody surface has dried up, there is left the
burnished antler, with its brown and roughened surface forming what
we know as deer’shorn. At the end of the season these antlers are
shed, breaking away from the bony bosses of the skull. Next year,
and in each successive year, they are re-formed by exactly the same
process, and in the simpler kinds of deer grow a little larger each
year but without much change of shape. In other deer, however,
each antler may branch, producing a second point or snag, and year
after year when the new antlers are produced, they may develop
additional points until noble heads such as those of fine red stags are
droduced, with as many as forty points on each antler. Young
CHILDHOOD AND YOUTH 13

deer, then, of species with branching antlers take a number of years,
very nearly corresponding with the number of points, to acquire the
full development of their kind, and the antlers they produce in their

 

Fic. 7. Three stages in the growth of the horns of the takin. a, at
six months old ; B, at two years old; c, young adult. (From an
example living in the London Zoological Gardens.)

earlier years resemble those of the simpler kinds of deer, and also
of their extinct ancestors.

Mammals, when they are born or very soon afterwards, closely
resemble their parents. The differences are due to greater likeness
to ancestors and to.their nearest allies, to the absence of special
weapons or ornaments, or to the presence of characters useful to the
young themselves.

Newly hatched birds, nestlings and fledglings are usually rather
14 CHILDHOOD OF ANIMALS

unlike their parents, but none the less fall into the second group of
young animals. The shape of the body, the head with its bill and
long neck, the wings, the absence of a true tail, and the single pair
of legs with the slender toes leave us in no doubt as to the group of
the animal kingdom to which the most naked chick belongs. Those
with only a slight knowledge of the families into which birds are
divided are able to tell, from the shape of the head and the beak,
and the number, arrangement and formation of the toes, whether
the young creature is a perching bird, a parrot, a bird-of-prey, a
wader, a duck or goose, or some kind of fowl or pheasant. Ornitho-
logists who have a minute acquaintance with the structure of birds
could place the young bird more accurately, but even the most
expert would sometimes make mistakes and often be at a loss.
The difficulty is due to many reasons. The first is ignorance. Eggs
and nestlings are a succulent prey for an innumerable host of
enemies, such as flesh-eating mammals of all kinds, and many reptiles
and even other birds. And so the nests and eggs and young are
protected by innumerable devices. They are carefully hidden or
placed in inaccessible spots ; they are shaped or coloured so as to
be invisible against their natural background. The parents visit
them by stealth, protect them with fury, or cunningly mislead those
in search of them. Eggs, moreover, and the skins of mature birds
are objects that are beautiful and attractive in the cabinet of a
collector, or in the cases of a museum, and not difficult to prepare
and to preserve. But nestlings and fledglings, even when they can
be got, must be kept as draggled little objects in spirits of wine,
a delight only to the expert naturalist. I should like to add that
although memories of boyhood, the human zest for sport and avidity
for knowledge steel the heart of the naturalist collecting eggs or
birds, there is an appealing quality of confident helplessness about
nestlings that few could resist. I have seen a German professor
putting young fishes into hot pickle with tears on his face, but the
born collector of young birds is generally hanged for more lucrative
crime. In any case, our knowledge of nestlings is defective.

Even with complete knowledge, I doubt if young birds could be
assigned to their proper species as correctly as similar identifications
could be made in the case of mammals. For all birds, in the elements
of their structure, are closely akin. Even the great families are diffi-
cult to separate, and species are distinguished chiefly by external
structures and especially by the differences in plumage. Young
birds may be naked, and so show nothing of the most distinctive
CHILDHOOD AND YOUTH 15

‘specific character; they may be downy, and the down of many
different kinds of birds is alike ; and they may assume several
successive plumages, none of which are like those of the adult.
Although, therefore, they certainly belong to the second group of
young animals, the resemblance with the parents is seldom close.
‘Young birds are certainly birds, and very often the group or family
to which they belong can be recognised.

When reptiles are hatched or born, they are in a much more
advanced state of development than occurs in the case of birds.
Not only is there no doubt as to their being reptiles, but they are
plainly crocodiles, lizards, serpents or tortoises, and although they
may be protected by their parents for a time, they are at once able
to move and to feed, and in their appearance and habits are miniature
copies of their own parents. ;

The three groups into which I am placing young creatures do not
correspond exactly with the different classes of animals, and the
Batrachians (frogs, newts, toads and their allies) and the fishes
lie on the border-line between the second and third groups. Some
frogs, when they are hatched, appear as little air-breathing, terres-
trial creatures quite like their parents, but most pass through
a tadpole stage, and tadpoles not only live very different lives from
the adults, but differ extremely from them in appearance. So
also amongst fishes, some of the sharks hatch in a form so like
their parents that they can be at once assigned to their proper
family and even species, and the young stages of eels were known
and given separate names as different kinds of fish long before there
was any idea that they were young eels.

The multitudinous tribes of animals without backbones, which,
in contrast with the Vertebrates (Mammals, Birds, Reptiles,
Batrachians and Fishes), are spoken of as Invertebrates, display
extremely different types of structure, but agree in usually having
a totally different appearance in the young and the adult stages.
There are some exceptions ; young spiders resemble their parents
in the fashion of reptiles and mammals, and here and there the
members of an individual family or group of invertebrates, unlike
their nearest relations, are hatched in a form differing from the
adult chiefly in size. These exceptions are usually cases of animals
that have taken to live in fresh water or on land, in circumstances
where the kind of young which is found in their nearest allies would
have difficulty in surviving. The nearest marine relatives of the fresh-
water crayfish, for instance, hatch out as delicate floating creatures
16 CHILDHOOD OF ANIMALS

extremely unlike their parents, but which would be carried away
by the currents in brooks and rivers. When the young crayfish is
hatched, it is a miniature crayfish which has only to grow and to make
a few trivial changes to reach the adult form.

The young animals in the second group appear in the world in a
form that is more or less like that of their parents, and reach
maturity by increase in size and by a gradual assumption of
the full character of the adult. Incidentally they show various
structures and characters that are of benefit only in the period of
youth and that have probably been acquired for that purpose. In
their younger stages they often recall the structure and appearance
of the younger stages of their nearest relations, and probably also of
the ancestors common to them and to their nearest relations. But
these ancestral resemblances are vague and uncertain ; the young
animals do not wish to display to us their pedigrees, but to become
adults as quickly and as directly as possible. Although, however,
it appears to be certain that animals do repeat, to some extent, the
history of their race in their individual lives, and compress into a
few weeks or months the results of countless centuries of evolution,
we cannot expect the repetition to be very perfect. And I think
we are led to the curious conclusion that the more directly an animal
develops, and the earlier it shows traces of what it is going to
become, the less it shows of its ancestral history. The path of evolu-
tion which was slowly traced by the ancestors of the animals alive
to-day, has been long and tortuous, sometimes direct for a time, often
twisting sharply to one side or the other, sometimes, perhaps, even
bending backwards. So far as it is possible, animals avoid these
devious ways in their individual lives and press on straight to the
goal. Inthe animal kingdom as a whole, and in each of its divisions,
the higher types tend to develop most directly and to show least
of their ancestral history.

Consideration of the third group of young animals, in which the
young stages differ much from the adult stages, requires a separate
chapter.
CHAPTER II
LARVE AND METAMORPHOSES

THE easiest way to begin to get a picture of the group of young
animals which are very unlike their parents is to remember that
many animals now live in surroundings quite different from those
of their remote ancestors. Although frogs are able to swim well
and often are found in water, they are really land animals. They
have lungs and breathe air, they hop about on land in search of the
beetles and other insects on which they feed, and many of them,
especially the green tree-frogs, never readily take to water except
at the breeding season, and others even lay their eggs on land.
The ancestors of frogs were fish-like animals, living entirely in the
water, with gills, not lungs, with a swimming tail and without hands
and feet. Probably in the course of a long period of time, and while
they were still aquatic animals, some of them began to swallow air
in the way that a number of fishes still get an additional supply of
oxygen, and probably also some of them had pouches on the gullet
into which the air was taken, as in the lung-fishes which still live
in the waters of Africa, Australia and South America. Many
different kinds of fish crawl on their fins over the mud at the bottom
of the water in which they live, whilst others creep out on the
edge of the shore and hop along in the surf. It is not at all difficult
to follow in imagination the slow changes by which such creatures,
living in shallow marshes, became more and more apt for terrestrial
life and thus truly amphibious, capable of living in water or out
of it. A long swimming tail is an inconvenient possession on land.
Newts and salamanders retain it, but are seldom able to move
quickly, and the fortunate ancestors of the frogs probably lost it.
The modern frog, however, instead of remaining amphibious, makes
the change from aquatic life to terrestrial life quickly, in a few days.
It hatches out as a tadpole, a fish-like creature with the head and
body in a single mass, continued behind into a long tail which is
adapted for swimming by the presence of a thin web above and
below. It has no limbs, and little tufts of gills protrude through
C.A. Mf B
18 CHILDHOOD OF ANIMALS

a slit at each side of the neck. It finds its food in the water, de-
vouring greedily almost any kind of animal or vegetable matter, with
a pair of horny jaws made up of a large number of horny teeth
closely set together. So it lives and grows for a few weeks. But
soon the limbs begin to bud out (Fig. 8), and the lungs develop, while
the tail shrivels, and in an extremely short time a number of internal
and external changes take place, and the tadpole suddenly leaves the
water and becomes a frog. Such a striking change, associated
with a change of habit, is called a metamorphosis, and the young
animal, before it has gone through the metamorphosis, is called
a larva. The method of development is plainly a very condensed
and quickened repetition of the ancestral history, and the larva
is equally plainly the modern representative of a remote ancestor.
We must not suppose, however, that the larva is the unchanged
: image of the ancestor.
The tadpole, when it is
..-, not swimming, anchors
~~ itself to water-weeds by
an adhesive apparatus,
; a kind of sticky sucker,
Advanced Tadpole of a Frog, with on the under surface of
the legs visible. 2 5
the head, just behind the
mouth. We have no reason to be sure that this organ, which differs
very much in different kinds of tadpoles, is a legacy from the ancestor ;
it may equally well be what is called a larval organ, a structure
developed for the benefit of the tadpole itself. So also the teeth
of the adult frog are true teeth, probably much more like the teeth
of the fish ancestor than the peculiar horny jaws of the tadpole.
These, too, may be new organs, developed for the benefit of the
tadpole. It is probable, too, that the tufts of gills visible from the
outside are new organs of the larve, and that another set of gills,
lying deeper in the gill-slits, but not present in all tadpoles, is the
true ancestral organ of respiration. Every larva is in this way a
composite of organs and structures some of which are ancestral, whilst
others are new and developed only for the larva. In some cases, like
the tadpoles of frogs, the ancestral element is greater, and we may
well believe that the larva is a fairly close copy of the ancestor. In
other cases, which I shall describe presently, probably the greater
part of the larva is new and gives us no true image of the ancestor.
The batrachians which lose their tails, the Anura, or frogs, toads
and tree-frogs, show almost every stage between a true meta-

      

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Fic. 8.
LARVZ AND METAMORPHOSES 19

morphosis and a direct development. In most of them the eggs are
laid in water and true tadpoles hatch out. In some the eggs hatch
on land, having been laid in holes, on grass or leaves, and when
the tadpoles are hatched, they wriggle into water or are washed
into pools by the rain. Inothers, again, the eggs are laid on land,
and the tadpoles have lost their gills before they are hatched, but
he metamorphosis is completed later on. In a few the complete

change occurs inside the egg, and when hatching takes place
little frogs appear, sometimes, however, with a stump of the tail
still left. In others the eggs are carried by the parent, and here, too,
they may be hatched as tadpoles or as perfect frogs. It would be
difficult to find a better example of the gradual change from a
type of development which is a repetition of the ancestral history,
to the higher type in which the young, as soon as they assume active
life on their own account, resemble their parents more or less closely.
The metamorphosis of the tadpole into the frog is a change from

a lower to a higher type of life. The larve of ascidians or sea-squirts
change by metamorphosis into an adult which must certainly be
regarded as a lower form of life. The eggs hatch into small tadpoles
which swim actively through the sea by vibrating the webbed
tail, the latter being stiffened by a simple kind of backbone in the
form of a rod of tough jelly. There is a hollow spinal cord, rather
like that in the very young tadpole of a frog, and in the front of this,
in the region where the brain of the frog’s tadpole is developed,
there is a simple kind of eye and ear. Near the mouth there
are adhesive organs by which the creature can anchor itself tem-
porarily. The mouth leads into a wide gullet pierced by gill-slits,
some of which at least correspond with the gill-slits of the frog’s
tadpole. At the metamorphosis, the larva fixes itself permanently,
at first by the adhesive organs, and afterwards by an outer jacket
or test which covers the whole animal with a protecting coat. The
tail with its representative of the backbone, the greater part of the
nervous system, and the sense-organs, disappear. The gullet and
‘the part of the body surrounding it increase in size, until they make
up the greater part of the bulk of the animal. The wall of the
gullet becomes transformed into a sieve, pierced by innumerable
holes through which the sea-water is filtered, leaving behind the
small particles which are used as food. The active, swimming
larva (Fig. 9); with a structure extremely like that of the lower
vertebrates, changes in this way into a hollow bag which sucks in
water by one hole and pours it out by another, and which, if we
20 CHILDHOOD OF ANIMALS

did not know its history, we should find very difficult to associate
with backboned animals. How far the larva of the sea-squirt
shows a repetition of the structure of its ancestors, or how far its

 

Fic. 9. Metamorphosis of an Ascidian. The upper figure shows the tadpole
adhering to a flat surface ; the lower figure shows the young Ascidian
similarly but permanently attached. (A fteyv LANKESTER, KOWALEVSKY
and HERDMAN; much magnified.)

shape and its organs have been formed and adapted for the purposes
of its own life, can only be guessed, and different zoologists have
made very different guesses. The most usual interpretation is that
the larva is in the main ancestral, and that the degradation of the
adult is pure degeneration. The sea-squirts are taken to be humble
relations of the vertebrates which became degenerate because they
LARVZ AND METAMORPHOSES 21

had adopted the habit of fixing themselves to the rocks of the coast,
and which, in the course of their development, show memories of
their high descent. But it is also possible to suppose that their
history has been different. It would be greatly to the advantage of
animals which are anchored in adult life if their young could move
about and settle down in new, less crowded, and perhaps more
suitable quarters. The swimming shape is no peculiarity of verte-
brates, and this tail and the directing sense-organs may be new
characters acquired for the purposes of the larva.

Flat-fish like the sole and the turbot show a metamorphosis
which is more easy to understand, and which occurs when the kind
of life led by the larve changes to that of the adults. Most bony
fishes have what we think of as the usual shape of a fish. They are
symmetrical, with the right and left sides of the body alike in shape,
colouring, arrangement of the fins and such paired organs as the
eyes. Whether they live near the surface of the sea, or haunt the
bottom, they swim in the same sort of position as we do when we are
using the ordinary breast-stroke, that is to say, the back is upwards,
the under side is downwards. The upper side, too, is much more
darkly coloured than the white or very pale under side. The newly
hatched larve of turbot, brill, halibut, plaice, soles and other
flat-fish have this familiar and symmetrical shape and coloration,
and when they begin to feed, pursue their small prey in the water
exactly like other predaceous fishes. When they have grown to a
little less than half an inch in size, however, a sudden change comes
about. The right and left sides of the body become very different.
In the turbot and brill the left side, and in the halibut, plaice and
sole (Fig. 10) the right side, become dark in colour, whilst the other
side loses any pigment it had and is almost completely white. The eye
of the uncoloured side rapidly moves, partly round and partly through
the head, until it comes to lie near the other eye on the coloured side
of the body. At the same time other changes in the shape of the
body and the position of the organs take place, so that the sym-
metrical larva becomes a distorted adult, what we would call at
first sight the upper side not being the real back of the animal, but
the right side in some cases, the left side in others. When the
metamorphosis is complete, the fish changes its habits. Instead
of swimming freely through the water, it lurks on the bottom, lying
flat on the sand or mud, with the coloured side uppermost. In
these cases there can be almost no doubt but that the larva, which
is like the great majority of fish, is the ancestral form, and that the
22 CHILDHOOD OF ANIMALS

change to the adult condition is a condensed and rapid repetition
of the slow ancestral history.

The forms of larve and the kinds of metamorphoses which occur
in marine invertebrates are many and varied, and the few examples
I shall choose will serve, I hope, rather to show the interest and
difficulty of the subject than to beguile readers into thinking they
or I understand it. Echinoderms, of which we all know starfish
and brittle-stars, sea-urchins and sea-cucumbers, crawl at the
bottom of the sea and show a radiate, generally a five-rayed, sym-
metry. That is to say, the organs of the body are arranged round

 

Fic. 10. Three stages in the metamorphosis of the Sole. (After FaBRE-
DomERGUE and Biétrix; slightly enlarged.)

a central axis, which is short in the flat echinoderms; such as the
starfish and brittle-stars, or long in the globular and oblong ones,
such as the sea-urchins and sea-cucumbers, like the spokes of a
wheel or the petals of a five-rayed flower. The eggs of most of
these echinoderms are very small, and soon after they are shed into
the water grow into little floating larve. The larve quickly assume
the shape of a thick-walled cup, the outside of which is covered with
small, waving threads of living matter, called cilia, and the hollow
of which forms the primitive digestive cavity. The cup grows larger
and longer, and its aperture narrows toasmall pore. Anew aperture
breaks through into the digestive cavity and becomes the mouth ;
the original aperture sometimes closes up, sometimes remains to
form the posterior aperture of the digestive canal. The larva
changes its shape, becoming flat, or even concave, on the side where
the mouth and anus lie, and remaining dome-shaped on the other.
LARV AND METAMORPHOSES 23

The flat side is now the ventral surface, with the mouth not quite
at the front end, the region in front of it being called the pre-oral
lobe, the anus being nearly at the hind end, and the curved surface
being the back, or dorsal surface of the larva. The cilia, which at
first covered the whole of the outer surface nearly equally, become
longer and stronger on a curved band surrounding the mouth, and
nearly, or completely, disappear elsewhere. As there is a front end
and a posterior end, a dorsal and a ventral surface, and a right and
left side, the larva shows what is called bilateral symmetry, and is

      
    
  

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Fic. 11. Larve of a Starfish: to the left a Dipleurula, to the right a
Bipinnaria, from the ventral surface. (After MorTENSEN; much
magnified.)

called a dipleurula. These larve move about in the water rather
actively, propelled by the cilia, feed greedily on floating micro-
scopic plants and animals, and as they grow, change into fantastic
shapes, different in the different groups of echinoderms, and so
unlike the adult form that many of them were described and named
before it was known what they were (Fig. 11). After a few weeks
they become sluggish, cease feeding, anchor themselves to rocks or
weed, and pass into the adult by a sudden metamorphosis, the
details of which differ in different species. It is always, however,
only a part of the larva that grows into the adult, the remaining
portion shrivelling up, or being cast off. In the starfish, for instance,
the attachment takes place by the end of the pre-oral lobe, which
forms a sort of stem from which the body of the larva projects, and
the young starfish appears on the left side of the larva, the organs
of that side forming the greater part of its structure, so that the
24 CHILDHOOD OF ANIMALS

change from the bilateral symmetry of the larva to the radial
symmetry of the adult is itself lop-sided and unsymmetrical.

There can be no doubt but that the greater part of this strange
life-history of the echinoderms, which seems more like the fantastic
changes of a pantomime than the orderly, deliberate processes of
nature, does not represent ancestral evolution. The early stages
up to the development of the dipleurula quite possibly recall the
structure of some remote and primitive marine creature from
which not only the echinoderms but other marine creatures may have
descended, for larvee of a similar type are found in the life-history
of many other animals. But the later stages and the curious mode
of transformation into the adult occur only inside the group itself.

Polygordius is a small worm which lives in the sand farther out
than the lowest tide-mark, rather in the way that an earthworm
lives in the garden soil. It is a bilaterally symmetrical, ringed
creature with the mouth nearly at the anterior end, with only the
portion containing the brain and a pair of sensitive tentacles in
front of it. It swallows quantities of sand, passes these through
its digestive canal, absorbing any contained food material.
The eggs are small, are shed into the water and soon grow into a
cup-shaped larva very like the early larva of echinoderms. In
the same way, the aperture of the cup narrows and a mouth breaks
through. The larva, however, then changes in a different way. It
becomes shaped like a top, with a tuft of sensitive bristles repre-
senting the upper pole of the top, the narrowed original aperture,
which becomes the anus, being at the lower pole, and the mouth
just below the widest part of the body. A band of long cilia, called
the velum, passes round the circumference of the widest part of
the body, just above the horizon on which the mouth is placed.
This larva, which has been named a trochophore and which is totally
unlike the parent worm, swims about, feeds and grows, and then
suddenly begins to change (Fig. 12). The region round the anus
grows out into the long-jointed body of the worm, which hangs down
from the floating bell-shaped larva like a tail, and becomes the
greater part of the adult worm, soon growing to many times
the original size of thelarva. The mouth of the larva remains as the
mouth of the adult, and the upper half of the larva becomes the
region in front of the mouth containing the brain, whilst the ring
of cilia disappears. The worm drops to the bottom and begins to
be a wriggling burrower in the sand.

The case of Polygordius, which I have taken as an example of
     

     

3

  

he

     

eC A

Fic. 12. Metamorphosis of Polygordius. Upper figure on left, trochophare larva 3
on right, later stage with worm growing out ; lower figure, much more advanced
stage, anterior end. (4ftey ParKER and RovuLE; much magnified.)
26 CHILDHOOD OF ANIMALS

many similar cases in marine worms, is very difficult to understand.
If the bell-shaped larva, swimming in the water like a transparent
jellyfish, represents the far-off ancestor, it baffles the imagination
to conceive the stages by which this should have evolved into
a creeping worm, by the elongation of the region round its anus.
It is much more simple to suppose that the worm developed directly
without any floating larva, and that the swimming disk was a
secondary development useful, like the wings of a wind-borne seed, to
carry the embryo about. If this be correct, the similarity between
the Polygordius larva and the larve of other marine worms, with
the larve of animals belonging to different groups of Invertebrates,

   

".
Alte

 

Fic. 13. Larve of a Gastropod Mollusc : left-hand figure, a Trochophore ;
right-hand figure, a Veliger. (Much enlarged.)

is, so tosay, a mere accident, due to the similar lives the larve lead,
and with little bearing on the ancestral relationships of these groups.

The large class of Molluscs contains animals of many different
types, such as oysters and mussels, whelks, snails and slugs, cuttle-
fish and squids. The period of youth is passed under many different
conditions, and especially in those that live on land or in fresh
water there are cases which we can see, by comparison with
their nearest relations, to be special adaptations to special circum-
stances. But there are two successive types of larvee found in so
many different molluscs that it seems as if they were at one time
stages in the life-history of all molluscs. The first is a trochophore
(Fig. 13), very like the trochophore of marine worms, and which
grows from the egg in the same way. It is more globular than
top-shaped, and the ciliated band, or velum, is nearer the upper
pole, so that the part in front of the mouth is smaller in proporfion
than in the worm-larva. This rapidly changes into the second type
of larva, called the veliger, and peculiar to molluscs. The velum is
drawn out into branches or lobes, and the portion in front of it ceases
to grow, so that it becomes a mere swimming apparatus carried
LARVZ AND METAMORPHOSES 27

at the anterior end above the mouth of the larva. The body
develops a hump on its back, and this is soon protected by a primitive
shell, and, on the lower side, behind the mouth, a flattened mass
forms the beginning of the muscular foot, the slimy organ on which
a slug or a snail crawls. The veliger gradually assumes the shape of
the kind of mollusc in which it is to grow.

It would have required a great deal of elaborate description and
the explanation of many details of structure familiar only to ad-
vanced zoologists, to give a just idea of the remarkable resemblances
between the larve of Echinoderms, the trochophores of Worms and
Molluscs, and the similar larve of some other marine invertebrates.
It is tempting to suppose that these different creatures follow
the path of a common ancestor while they are living the free-
swimming life of that ancestor, and then sharply diverge to reach
their different goals. But we have to remember that a meta-
morphosis cannot be a primitive mode of development, and that
where it exists a long history has been blotted out. And we have
also to remember that the resemblances of the larve are in plain
relation to similar habits, and may have no ancestral meaning.

The great class of Crustacea includes crabs, lobsters, crayfish,
prawns, shrimps, sandhoppers, woodlice, barnacles and water-fleas
and many less well known creatures. Like insects and spiders,
they have jointed limbs, arranged in pairs, and the body is covered
by a hard external case to the inside of which the muscles are
attached, and which is usually known as the shell. Most of them
live in or near water, and the terrestrial forms show plain traces of
aquatic ancestry. The young of many of them, especially those
that live in fresh water or on land, pass through their period of
youth in fashions that are quite clearly direct adaptations to the
special circumstances of their lives. The marine crustaceans
usually lay small eggs which hatch out into larve extremely unlike
their parents, although the external shell and jointed limbs show
plainly that they are crustaceans and betray no resemblance with
any other group of the animal kingdom. The larve swim about,
feed, and after a few days or weeks the hard shell becomes too tight
for the plump body, and splits open, setting free the animal, clad
in a soft skin and at once swelling to a size rather larger than that of
the case from which it emerged. Very quickly the skin hardens
to form a new shell, and this second larva is not exactly like the
first larva, but rather more complicated, and more near the adult
form. The same sequence is followed again, and may be repeated
28 CHILDHOOD OF ANIMALS

in many successive moults, until a moult comes after which the young
creature has the final form of its species. The seas teem with
these larve, especially in summer, when the water is warm. They
feed on one another, and on the small floating plants which, like the
green herbage of the land, are the ultimate food-supply of the living
world, and they themselves are preyed upon by hosts of fishes.
The larve appear in many curious shapes, but in those cases where
there are the greatest number of successive larve and moults be-
tween the egg and the adult, the series shows a rough correspondence
with what may be supposed to be the ancestral history of the
crustacean in question. In those with fewer larve the jumps are
bigger, some stages being suppressed, whilst the regularity of the
sequence is often confused by the premature appearance of some of
the organs or appendages, and the retarded appearance of others.
The starting-point in those larve in which the series is most com-
plete, and which appears in more different kinds of crustacea than
any other larva, is what is called the nauplius. The nauplius
(Fig. 14) has an oval body, not divided into rings or segments,
with a large median eye on the dorsal surface of the anterior end.
It has a mouth on the ventral surface, under the eye, protected by
a kind of membranous upper lip, and it has three pairs of swimming
appendages, the front pair of which occupy the position of, and
correspond with, the antennules or front pair of feelers of the lobster
or crayfish. Those of the second pair are forked, and usually have
hooks at their bases which lie on either side of the mouth and serve as
jaws. They correspond with the antenne, or second pair of feelers
of the adults. The third pair, situated a little farther back, are also
forked and correspond with the mandibles or true jaws of the adults.
In prawns (of the genus Pen@us) the nauplius larva is succeeded
by a larger larva called the metanauplius (Fig. 14), in which the
swimming parts of the third pair of appendages are smaller whilst
a strong jaw portion is developed. Behind, there are the beginnings
of four other pairs of limbs. Next comes a protozoéa larva with
the same seven pairs of appendages, a carapace or shell beginning to
spread over the dorsal surface of the anterior part of the body,
and a long, forked, but unjointed abdomen. The third pair of
appendages has ceased to be of use in swimming, and is wholly
transformed to the pair of jaws or mandibles. The paired eyes begin
to show through the carapace. For several successive moults
there is not much change in shape, but the eyes push through the
carapace, and the abdomen becomes longer, is divided into joints,
LARVZ AND METAMORPHOSES 29

 

 

1

Fic. 14.  Larve of the Crustacean Peneus. Upper left-hand figure,
Nauplius ; upper right-hand, Protozoéa. Lower left-hand figure, Zoéa ;
lower right-hand, Schizopod stage. (After F. MULLER and Craus ;
much enlarged.)

and shows the buds of more pairs of limbs. In the next stage, which
is called the Zoéa (Fig. 14), the paired eyes have become movable,
being mounted on long stalks, the carapace projects in front as
30 CHILDHOOD OF ANIMALS

a long spine, and the abdomen is very long, almost devoid of appen-
dages along the greater part of its length, but witha large pair on the
second last segment. After several moults, with further slight
changes, a larva appears which is called the mysis stage or schizopod
stage (Fig. 14), from its resemblance with the adult form of a lower
kind of crustacean. In this stage the projecting spine of the carapace
is very long, the abdomen has a complete set of swimming limbs,
those of the last pair being large and forming with the last segment
itself a swimming tail-fan like that of an adult lobster or prawn.
In a further set of moults the complete shape of the adult is
acquired by the body and limbs.

In most of the higher Crustacea, the number of moults is smaller,
and there are bigger jumps between the successive types of larve.
The earliest larva of crabs is a fully formed zoéa, which is dis-
tinguished from the zoéa of other Crustacea by a very long spine
on the carapace, but, almost immediately after hatching, a thin
cuticle is cast off, and this differs from the zoéa itself and appears to
be the last remnant of one of the suppressed larval stages. Next
come a set of larve called the megalopa stages; which quickly acquire
the appendages and general form of the adult crab, but which have
a long extended abdomen. After the moult from which an animal
that can first be called a crab appears, the abdomen is tucked up
under the body as a rudimentary triangular flap.

Study of the larval development of a very large number of marine
crustaceans, of which I have chosen only a few examples, would
seem to give a clear picture of the general course of events. Because
they have a hard, shell-like skin, young crustaceans cannot grow
larger in the usual way of soft-skinned animals. They must grow
in size by a succession of moults. This makes it impossible for the
youthful period to be a time of slow and continuous change, from
the first larva to the adult. The changes must take place by jumps.
Where there are a great many different successive larve, each a
little more complicated than its predecessor, we seem to see the
simplest method of arriving at the result, and the greatest probability
that the larval history is at least partly a repetition of the ancestral
history. And the facts that many of these larve are closely alike,
although they belong to different groups of Crustacea, and that the
larvee of the higher groups not infrequently resemble the adults of
the lower groups, greatly increase the probability of this ancestral
interpretation being correct.

Insects, like Crustacea, are Arthropods with a hard external
LARVA AND METAMORPHOSES 31

skeleton and jointed limbs, and in their development show a series
of moults. No life-history in the animal kingdom is more surprising
than that of a fly like the blow-fly. The eggs are laid on animal
matter, and the flies, no doubt attracted by the smell, prefer matter
that is just beginning to soften with putrefaction. The eggs hatch
out into the little brown-headed white maggots known as gentles
(Fig. 15). They have a pair of strong jaws with which they devour
the animal matter in which they are living, a segmented body clad
in a tough leathery skin, and no trace of limbs. They moult two
or three times without changing their shape, but growing larger,
and soon after the last moult, contract into a quiescent oval body,
covered with the skin of the larva which has become dry and brown.
‘After some days passed in this a
motionless state, the brown skin |
splits, and the fully formed adult ¥
fly emerges, and in a few minutes
is winging its way through the air,
as unlike the worm-shaped larva
as any creature could be. With
the exception of the nervous
system and parts of some other .. ae; | Raa (ee eee) Bad
organs, it seems as if the whole of pupa (lower figure) of Blow-fly.
the organs inside the hardened skin ee and PACKARD ;
of the larva melted down and
became rearranged to form the very different organs of the adult.
Patient and extremely difficult dissections, however, have shown
that there is an intelligible order in this transformation. Some
time before the fly emerges it is surrounded by two delicate and
transparent skins. The inner of these, if we could imagine it taken
out whole, plumped up with air, and dried, would have the appear-
ance of a fly with a head bearing antenne, eyes and mouth-organs,
a body with small wings and six-jointed legs, and a pointed abdomen,
but with all these organs and parts, and especially the wings, not
quite like those of a modern fly, but rather simpler. This skin is the
pale ghost of a former metamorphosis, of a true moult once passed
through by the ancestors of the flies, but now on its way to be
suppressed. The outer thin skin is the similar remains of a still
earlier moult, and its structure, although still fly-like, is less fly-like
than the inner skin.

The development of a moth such as the well-known privet hawk-
moth carries the story a little further. The eggs are laid on the

 
  

 

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32 CHILDHOOD OF ANIMALS

privet and hatch into caterpillars which feed on the leaves. The
caterpillar (Fig. 16) has a head and a jointed worm-like body.
The head has six simple eyes, a pair of three-jointed very small
antenne, and biting jaws. The first three segments of the body
carry each a pair of five-jointed clawed legs, corresponding with the
legs of the adult insect. Four of the other ten segments carry each
pair of larval legs, called prolegs, and not represented in the adult,
but entirely for the purposes of the larva. The caterpillar feeds and
grows, and moults three or four times. Before the last moult,
it becomes restless and wanders about, ceasing to feed. It is ready
for pupation, and is
> seeking a_ suitable
‘fy place. Some cater-
_/’ pillars suspend them-
selves to the branch
of a tree or to a pro-
jecting point in a dry
= meeeeecrevice. Others spin

ae “a cocoon of silk.
Others, such as the
privet hawk - moth
caterpillar, descend to
the ground and scoop
out a dry burrow.

Fic. 16. Caterpillar (upper figure) and Chrysalid (lower There the last moult
figure) of Privet Hawk-moth. (Slightly reduced.) takes place and the
2

   

pupa or chrysalid (Fig. 16) emerges, and very quickly becomes
hard and brown. If it be examined closely, however, it can be seen
to resemble a moth more than a caterpillar. It shows the shape of the
head, body and abdomen of the moth and carries the appendages of
a moth, not of a caterpillar, and is provided with short, folded
wings. These are at first free, but soon, before the skin has become
dry and brown, are glued down with a sticky secretion. The pupa
is able to wriggle, but remains practically motionless while the
transformation to the adult is taking place. In the course of this
there is a suppressed moult, shown by the presence of a very thin
skin covering the body of the moth inside the pupa-case, like one of
the two skins in the blow-fly, and like these representing an almost
forgotten moult. When the moth emerges, it is ready to fly as soon
as its wings have expanded and dried, and it is extremely unlike the
caterpillar. But the gap is not so great as in the blow-fly. In the
LARVZ AND METAMORPHOSES 33

first place, the pupa or chrysalis is much more like the moth than the
puparium or skin of the blow-fly larva is like the blow-fly. In
the second place, the caterpillar, with its antennae, eyes and three
pairs of jointed, walking legs, is much more like an insect than is the
legless maggot.

Some small insects of which the oil-beetle is a good example
expand the contracted history of the higher insects still more.
The eggs hatch out into active larve showing a head bearing eyes
and antenne, a body of three joints each bearing a pair of fully
formed clawed legs, and a jointed abdomen with a pair of long
bristle-like projections behind.
These larvee (Fig. 17), although
they have no wings, are insect-
like in form, and are called ,-
Campodeiform larve; no one ,
observing them for the first
time could doubt but that
they are insects of a primitive
kind; moreover they are ex-
tremely like the members of
the lowest group of existing
insects, the Aptera or wingless = ole
insects, of which the silver-fish a tee ee oes te Cameaden
and the bristle-tail are well- form larva; middle figure, maggot-
known examples. These larve Poo ey (Afier
run about, climb up flowers,
and have the instinct of clinging to any hairy object. Ifa bee
comes their way, on a visit to a flower, they at once seize hold
of its hairy body. If it is an unsuitable bee, they perish, but
if it is the right kind for their purpose (Anthophora or Andrena)
they are carried te the nest of their host, and when the bee lays
an egg in a cell, the larva slips off and climbs on the egg which
is floating in the honey. The larva eats the contents of the egg
and then moults. The second larva which comes out is much less
like an insect than the first ; it is a fleshy grub, not well divided into
head, body, and abdomen, and with three short pairs of legs. It is
intermediate between the degenerate maggot of the blow-fly and
the caterpillar of the moth. This grub floats in the honey and
devours it and then moults once more, a still more degenerate motion-
less form appearing, with no movable appendage on the head and
with only six stumps in the place of the legs. This in its turn

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Gey
34 CHILDHOOD OF ANIMALS

moults and changes to a pupa rather like the adult in form, with
the appendages and rudimentary wings glued down to the body.
After a resting stage this pupa opens and the adult insect emerges.

The eggs of other beetles may hatch out either as campodeiform
larve, or as maggot-like larve, which, after moulting, produce
pupe with rudimentary wings. The eggs of many other insects,
such as cockroaches and earwigs, hatch out as campodeiform larve,
and then by a series of moults slowly acquire the adult form without
any true metamorphosis.

Finally there are many insects, such as the locusts, in which the
earliest stages have been suppressed and there is no sudden meta-
morphosis, but the period of youth is occupied by a series of moults
(Fig. 18), in which the successive larve slowly assume the
characters of the adult, the wings gradually growing longer.

I do not wish to suggest that the examples I have chosen represent
actual stages in the evolution of insects. They have been selected
from insects that are by no means closely related, and they do no
more than give an idea how the extremely different modes in which
modern insects develop show a trace here and a trace there of
different parts of a common ancestral history, some parts of which
have been blurred and condensed in some insects, other parts in
others. The delicate and transparent pupal skins surrounding the
fly inside its puparium, with their rudimentary wings, and the pupal
cases themselves of moths and oil-beetles with their rudimentary
wings, plainly represent the active later larval stages of the locust.
The campodeiform larve of the oil-beetle and of many other beetles,
cockroaches and earwigs represent the primitive insect, and may
pass by a series of moults into the adult, or these later stages may
have been condensed to a sudden metamorphosis. The caterpillar-
like larva is a rather degenerate modification of the Campodea
larva, and the maggot-like larve of many beetles and the legless
larve of flies are still more degenerate interpolations in the life-
history, fitting the special conditions in which these larve live.

The stories of the youthful period in the crustaceans and insects
are, to a certain extent, alike. The hard nature of the skin has led
to a replacement of the more usual method of continuous growth,
by growth in little jumps, there being a moult at each jump. In both
there are many animals in which these successive moults separate a
set of larve which are becoming more and more like the adult by
slow stages. In both the more continuous sets of larve seem to be at
least a partial repetition of the ancestral history, but in both the,
 

Fic. 18. Development of a Locust. The upper figure, showing the
youngest stage, is considerably more enlarged than the others, which
are all magnified to the same scale. (After PACKARD.)
36 CHILDHOOD OF ANIMALS

larve are modified in many ways to suit the needs of their own life,
and it is a difficult judgment to decide in any case how much of
the character of a larva is adaptive and how much ancestral. In
both groups the continuous series may be interrupted at any point,
by the obliteration or telescoping of some of the stages, with the
result that occasionally a moult is preceded by a resting phase in
which the larva is more or less torpid and motionless, and when the
form that emerges from the moult is widely different from the
preceding form. Such bigger jumps give rise to the familiar
metamorphoses, and they are most frequent and most decided when
they are associated with a change in the habits of the creatures
before and after the metamorphic moult.

There is one striking difference between the two groups. Amongst
insects the campodeiform larva, which is certainly the most primi-
tive, represents the most primitive group of living insects, and, more-
over, helps to link insects with another group, the group of centipede-
like animals. In Crustacea, the nauplius larva, which is certainly
the most primitive, does not represent any living group of Crus-
tacea and does not link the Crustacea directly with any other group.
Unlike the campodea larva which, but for the absence of reproductive
organs, has the appearance and characters of an adult animal, the
nauplius larva is plainly an immature creature.

When Darwin first convinced naturalists that the living world as
we see it now had come into existence by a process of evolution, the
resemblance amongst the larve of different animals, the resemblances
of the larve of one set of animals with the adults of lower animals,
and the parallel between the larval development and the possible
ancestral history were thought to provide almost clear proof of the
fact of evolution and to show the actual path of evolution. But
although increase of knowledge has strengthened the general case
for evolution to such an extent that a reasonable naturalist can no
longer doubt it, we are getting more wary as to particular cases.
The struggle for existence amongst larve is extremely severe; of
the multitudes that are hatched, only a few reach adult life, and
then only after having escaped almost incredible dangers. And so
larvae have been shaped and moulded, coloured and armed in a
multitude of ways that fit them to the conditions in which they
live. And in this process they must have lost much of their in-
herited ancestral characters and must have acquired many delusive
resemblances.
CHAPTER III
THE DURATION OF YOUTH IN MAMMALS

T ENTERED the University of Aberdeen a few weeks before I was
sixteen years old, and it pleased me to find that most of those in
my class were several years older. Kind relatives endeavoured to
chasten my pride by telling me of various distinguished professors
who had joined when they were only twelve or thirteen years
of age. As I had not then learned the folly of meeting the reproofs
of my elders with rational arguments, I replied by saying that in
those prehistoric days University education was on a lower grade,
and that students matriculated before they had begun to learn Greek
or Mathematics. And I have no doubt but that to-day many of
the first year’s courses at the Universities begin where we left off.
So also it is with most of the pursuits of life. In business, in handi-
crafts, and in professions the period of education (in the common
sense of the word) is growing longer, and youths are older when they
emerge from the pupillary stage. But although they are older
in years, I do not think that they are physically older. They retain
the flexibility, the high spirits, the sense of irresponsibility, and
many of the purely physical characters of youth, such as practical
indifference to the other sex, for a longer time. In the civilised
races and especially in the more intellectual classes, the some-
what indefinite transition from youth to manhood does not
occur till after the age of twenty. There is a parallel change in the
case of women. Our grandmothers were married and became the
responsible heads of establishments at ages of thirteen, fourteen, or
fifteen years, an arrangement which would be regarded as scandalous
to-day. The transition from boyhood to manhood or from girlhood
to womanhood, using these somewhat indefinite terms in the widest
sense, comes later. No doubt there are racial differences as well
as differences of civilisation and of class, and in the case of Europe
the long-headed, dark-skinned peoples along the northern shore of
the Mediterranean, although they may be equally civilised, mature

at rather earlier ages than the round-headed peoples of Central
37
38 CHILDHOOD OF ANIMALS

Europe or the long-headed, fair-skinned natives of the North. But
amongst these, too, the period of youth is stretching out, and we
may fairly say that youth in civilised man lasts for at least twenty
years. Exact observations on the lower races of man relating to
this point are not very numerous, but there is a general agreement
amongst those with knowledge that both males and females of the
lower races mature much earlier. Probably it would be fair to set
down from twelve to fifteen years as the duration of youth in most
of the lower human races.

The animals that approach man most closely in size and structure
are the anthropoid or man-like apes. Gorillas, which live in the
tropical forests of West Africa, are larger than human beings. They
are much more bulky, and their legs and arms are longer. A full-
grown male, if it stood perfectly upright, would be considerably
more than six feet in height. Chimpanzees, which live in the same
parts of Africa as the gorilla, but also extend much further to the east,
have long arms and legs, but are not so large and heavy, and even
if fully upright would seldom reach five feet in height. Orang-utans,
which are natives of Borneo and Sumatra, have relatively longer
legs and arms than the others, but are even less upright. The
largest orang is not more than just over five feet in height, but the
great bulk of their bodies exceeds that of ordinary human beings
and is intermediate between the bulks of the gorilla and chimpanzee.
The gibbons, of which there are many species, ranging over a large
part of tropical Asia, are much more erect in posture than any of the
other anthropoid apes, and their arms and legs are extremely long.
Their bodies are slight, and the largest specimen of the largest species
probably is not more than four feet in height, and is therefore
smaller and lighter than a human being.

The gorilla, the chimpanzee and the orang carefully avoid the
neighbourhood of man, and although gibbons are less shy, their
life, passed chiefly in the tall trees of forests, makes careful and
prolonged observation difficult. We have therefore no exact
knowledge of their breeding habits, or of the duration of their youth
in the wild condition. They are notoriously difficult to keep alive
in captivity. One gorilla lived for several years in the Zoological
Gardens at Frankfurt ; all the great Zoological Gardens have made
many attempts, but these apes seldom live for more than a few weeks
after their arrival. Orangs were long supposed to be equally delicate,
but more recently there has been greater success with them, and at
the present time there is alive in the London Zoological Gardens a
DURATION OF YOUTH IN MAMMALS 39

fine male which has been there for seven years. Chimpanzees are
obtained in much larger numbers and, although they are very delicate,
individuals have frequently lived in captivity for a number of years.
The “record ” is held by the London Society, and in the Gardens at
Regent’s Park there is a chimpanzee which has lived for fourteen
years. Unfortunately it is a dwarf, either congenitally or as the
result of the artificial conditions in which it has lived. Individual
gibbons have lived for several years, but in most cases they too
succumb very quickly.

I do not know if anthropoid apes would be likely to breed in
captivity, but as most of them are taken when they are very young
and do not live to maturity, there has been no opportunity, and I
do not know of any case of a birth having taken place in menageries.
Unfortunately, also, it is certain that little reliance can be placed
on the rate of growth of the apes in captivity. Better accommo-
dation, less coddling and more reasonable food are certainly im-
proving the general health of captive apes, and probably their rate
of growth is often more natural than it used to be. But we have
still to rely chiefly on comparisons with human beings, based on size,
the appearance of puberty, the closing of the skull bones, changes
in the teeth and so forth, and there is no reason to be certain that
such comparisons are not misleading. It is generally assumed,
however, that the duration of youth in anthropoid apes is from
eight to twelve years, and the estimate is probably not very far
wrong.

The lower monkeys range in size from the large baboons, which
exceed gibbons in bulk and weight, to tiny monkeys like marmosets
which may be no larger than a small squirrel. Although on the whole
they are also rather delicate in captivity, so many have been kept
by private persons or in public institutions that it is not surprising
that there have been frequent successes. Many different species
have been bred in captivity and reared to maturity. The larger
monkeys, like baboons and mandrills, take from eight to twelve
years to grow up. Middle-sized monkeys, like common Asiatic
macaques, take from three to five or six years. A pair of Japanese
apes in the London Zoological Gardens were the parents of a baby
born in January 1906 ; in the beginning of 1912 the young one was
nearly, but not quite, fully grown. It lived with its parents in an
enclosure consisting of an open-air cage about ten feet by ten in
area, provided with branches on which to climb, and with an un-
heated, covered sleeping-den. Although the conditions were better
40 CHILDHOOD OF ANIMALS

than those often given to monkeys in captivity, I am inclined to think
that they were not varied enough, nor exciting enough for the
normal rate of growth. The small American monkeys, such as mar-
mosets, become full grown in from two to three years.

The length of the period of youth thus becomes shorter and
shorter as we descend from the highest human types to the lowest
monkeys, and is parallel with some other qualities of this group of
animals. The potential longevity, the age to which an animal can
attain under the most favourable conditions, is greatest in the higher
races of man, where it may be a century, seldom exceeds fifty or
sixty years in the lower races of man, and,so far as the somewhat
scanty evidence at our disposal goes, decreases as we pass down the
scale of monkeys from the man-like apes to the simplest little
monkeys. It cannot be said, however, that there is any definite
proportion between the length of youth and the length of the whole
life, in the fashion that the Greeks supposed the height of the head
to be a definite proportion of the total height. The span of a com-
plete life is not divided according to any ideal rule or law into so
many parts for helpless infancy, so many for aspiring youth, and
so many for maturity. Each portion varies with the particular needs
of the particular species, and no more is to be expected than that
the mode of division should be rather more alike amongst species
that are nearly related, and rather less alike amongst species that
are far separate.

There is also a rough correspondence between the duration of youth
and the size of the creatures in the man-monkey group. A full-grown
male gorilla, it is true, is larger, although not taller, than a finely
built man, but the human race as a whole consists of larger and finer
animals than the anthropoid apes, whilst these in their turn exceed
the baboons, which exceed the ordinary monkeys of India and
Africa, and so on down to the tiny marmosets. It is tempting
to suppose that it must take longer to grow into a big animal than
into a little animal. This also is true only when nearly related
creatures are compared. Mere increase of bulk tells us little. A
mushroom grows much more quickly than a daisy, a gooseberry
and a huge vegetable marrow take nearly the same time to swell
out. A human child takes nearly two hundred days to double its
weight at birth, whilst new-born mice quadruple their weight in
twenty-four hours. The nature of the organism, the complexity
of its structure and the particular conditions under which
it lives must all be taken into account, and are of more
DURATION OF YOUTH IN MAMMALS 41

importance than actual size. Within each group of nearly related
animals, the duration of youth is in rough agreement with the
possible span of the whole life, and with the relative size to which
the members of the particular species attain. But the agreement
is not exact. There are very many instances in the animal
kingdom, and I shall mention some of them, in which there is no
reasonable proportion between size or the potential longevity, and
the duration of youth.

The descending scale from man to the lowest monkeys, which is
fairly plain in the case of size and of longevity, is quite certain if we
take into consideration the complete structure and especially the
Mental capacities of the members of the series. When animals
belonging to different groups are compared, it is not very easy
ie say which is to be regarded as higher and which lower. Most
persons would agree that the cats, including the large cats like the
lion and the tiger and the small cats like the domestic cat, are the
highest of the carnivorous animals. But is a cat a higher or lower
animal than an elephant ? Inside a group, however, comparison. is
easier, and especially if we take into consideration the size and
structure of the brain, there is no doubt but that man stands
supremely at the head of his tribe and that there is a rapid descent
from him to the lowest monkeys. The most certain and the most
important feature about the differences in the duration of youth,
and what is specially clear in the case of man and his relations, is
that the length of the period of youth varies with the degree of
intelligence to which the adult can attain. Civilised man is the
most intelligent and takes longest to grow up ; the smallest monkeys
are the least intelligent and hurry over the period of youth most
quickly.

As a good many of the Carnivora have bred in captivity, we have
a fairly extensive knowledge of the duration of their youth, although
it is to be remembered that the new conditions to which they are
subjected may have an effect on their rates of growth, probably
accelerating it. Lions and tigers take only from three to five years
to become adult ; both sexes are capable of breeding, and the males
have got good manes soon after they are three years old, but they
may go on growing for several years after that. Leopards, lynxes
and caracals and the smaller cats generally, take from one and a half
to three years to become adult. A jaguar cub born in the London
Zoological Gardens was not nearly half grown when it was a year
old. Although it was brought up by its mother, it soon became
42 CHILDHOOD OF ANIMALS

rickety and did not live to maturity, so that its rate of growth was
abnormal. Caracals are a good deal smaller than jaguars or
leopards, and their cubs are nearly full grown when they are
a year old; probably from one to two years is the duration of
their youth. Bears take longer to grow; brown bears require
nearly six years, and Polar bears still longer to become adult.
The fur seal has been observed very closely in its breeding haunts,
and it has been ascertained that it is not adult until it is four
years old, but both sexes and especially the bulls continue to
increase in size after that age. Among domestic dogs there is
almost an exact parallel between size and the duration of youth.
They all mature quickly, but mastiffs are hardly mature at two
years old, large hounds and greyhounds at about eighteen months,
pointers and setters at from eighteen to fifteen months, whilst
fox terriers are adult at about a year and toy dogs at even less.

Badgers are born in February or the beginning of March and
remain with the mother until the autumn, when they look after
themselves. They are practically adult at a year old, but may
continue to grow for another six months, the males, as in most
mammals, taking rather longer to fill out. Otters are born in
almost any season of the year and are adult in about ten months,
but may continue to grow for a few months longer. Weasels,
martens and polecats all take from nine to eighteen months to reach
their full size.

It is impossible to arrange Carnivora in a scale extending from
the highest to the lowest in the fashion which can readily be done
with man and monkeys. They are all animals of a high type and
all show considerable intelligence, power of adapting themselves to
new situations, acquiring likes and dislikes to individuals, and
showing their distastes and preferences in the plainest way. No
doubt memory and the sense of locality have been specially developed
in the dog, because of its long association with man and from the
effect of selective breeding for qualities that man appreciates. My
tame caracal, which came from a stock certainly not modified by
human agency, learned the ways of a house as perfectly as any
domestic cat or dog. He allowed himself to be handled by those
he trusted with complete confidence, to take food or medicine from
a spoon, to have his claws cut and his ears cleaned out with disin-
fectant. He disliked being left alone and always followed his
owners from room toroom. At night, before going to bed, he went
‘to the box that was prepared for him, and then came to have his feet
DURATION OF YOUTH IN MAMMALS 43

wiped, a process he much disliked. He usually slept on a bath
towel alongside my pillow, but on several occasions, for various
reasons, he slept under different conditions, sometimes for a few
days at a time, once for more than a month. On coming back he
at once went to his old place without any hesitation. It is the instinct
of a cat to pounce on any moving object, and he had some difficulty
in learning that a knee or a foot moving under the bedclothes
was not legitimate prey. But he learned this, and he never had to
be taught not to lay hold of the face or hands. If it were cold at
night and he wished to be taken under the blankets, or if he wished
to leave the room, he would arouse me by stroking my face with his
paws. I believe it is the experience of every one who has been at
the pains to make friends with any of the wild Carnivora that they
show as much intelligence as the domesticated forms. There is
no parallel between size and intelligence among Carnivora; the
sizes to which the different species attain seem to be associated
with their habits of life rather than with their place in the scale.
Youth lasts longest in some of the larger forms; in all of them
it is shorter in proportion to size than in man and his allies, and in
most of them it is absolutely shorter than in most of the near
relations of man. If the two groups be compared with regard to
size, the difference is very striking; the largest carnivores, such
as bears, lions and tigers, are much larger, more bulky and more
powerful animals than gorillas and chimpanzees, but reach maturity
much more quickly.

The vegetarian terrestrial mammals belong to distinct groups
which are not at all closely related and which must be considered
separately.

Elephants are the largest and heaviest of existing land animals.
The African elephant reaches a greater size and bulk than the
Indian species ; the tallest wild specimen whose height has been
recorded was shot in Abyssinia and stood 11 feet 84 inches at the
shoulder ; Jumbo, the largest African elephant that has been in
captivity, was Ir feet high when he left the London Zoological
Gardens, and is stated to have reached 12 feet before he died in
America. An Indian elephant 10 feet 6 inches in height is unusually
large. A moderately sized elephant, of about 7 feet high, weighs
from 2 to 3 tons, and a really fine example between 5 and 6 tons,
Jumbo having weighed 6} tons. Elephants grow slowly ; the dura-
tion of their youth is from twenty to twenty-four years, a very much
longer time than that occupied by the youth of any other terrestria]
44 CHILDHOOD OF ANIMALS

mammal except man. If, however, we remember that a full-
grown elephant weighs as much as fifty full-grown men, and that
these animals have some difficulty in obtaining the enormous
quantities of food they require, the length of their youth is not so
remarkable. I think that their intelligence has been not a little
over-praised. They are docile, except at special periods of their
life, and can be taught to perform different kinds of simple labour
and to obey commands. But even in the case of the highly trained
animals of the circus ring, if the tricks be carefully studied it will
be seen that they require none of the mental powers shown by dogs,
cats, sea-lions or monkeys. Trainers of elephants have told me
that they can count on no powers of imitation or originality on
the part of their pupils, but have to teach the animals each distinct
movement of the performance separately. Elephants have good
memories, and take strong likes or dislikes to individuals, but those
best acquainted with them disbelieve the familiar stories as to their
saving the lives of their keepers and so forth.

There is no group of living animals closely related to the elephants,
but it is probable that the hyraces, rock-rabbits or dassies are their
nearest allies. The largest of these animals is no bigger than a hare,
and there are different species found in Syria, Arabia and Africa,
As they practically never breed in captivity, not much is known
about their youth. I hada young West African tree-hyrax brought
to me recently which had been taken by its owner when it was in his
opinion only a few days old, and which at six months old was
not half grown. It is probable, therefore, that the youth of
these animals lasts more than a year. I had never seen a tame
tree-hyrax before, and this little animal interested me very much.
Its owner, who was a mining engineer, did not happen to know
anything about the natural habits of his pet, except that it lived in
the tops of tall forest trees. He could not get it to eat for some time,
and in despair stuffed it with bread and milk. It ate on its own
account afterwards, but usually required to be coaxed, which he
did by making a sucking noise with his mouth and pretending to eat
himself. Persuaded in this way, it took milk with rice, bread or
biscuit, hard-boiled egg, apple, lettuce and even pieces of cooked
fish. It liked companionship, following its owner about. It
made itself at home in my house at once, exploring everything,
clinging up the legs of chairs and on the shelves of bookcases,
generally making a low chirping purr. It liked rubbing its fur and
especially the white hair along the glandular patch on its back against
DURATION OF YOUTH IN MAMMALS 45

my clothes. When it was angry it stamped with its fore-paws on
the ground. It had quite an unusual degree of character and
intelligence, and a most restless curiosity.

The Odd-toed Ungulates, the rhinoceros, the horse and the tapir,
have a period of youth the length of which is roughly in proportion
to the size of the animals, but which is relatively rather shorter
than that of the elephant and the hyrax. A young rhinoceros
grows very quickly at first and runs with its mother until it is nearly
full grown. The limit of size varies a good deal in the different
species, and actual growth appears to go on for a great many years,
but so far as can be ascertained the animals are adult at seven or
eight years of age. Horses and asses have been much influenced
by domestication, and the period of youth has been made shorter in
some of the breeds. Horses, asses and zebras are certainly adult at
five years of age, and the average duration of the period of youth is
less, probably from three to four years. Tapirs mature very
quickly ; when they are born they are striped and blotched with
white, so that they are very unlike their parents (see Plate VI,
p- 94). In four to six months this youthful coloration disappears
and they resemble their parents in pattern. The duration of
their youth is said to be under a year, a very short time for animals
of their size, but certainly some individuals at least continue to grow
for much more than a year. The rhinoceros and the tapir are
rather unintelligent animals with low mental powers. The horse
has been so much modified by association with man and by
selection for special qualities which are useful or pleasant that
we are disposed to have a false idea of its mental powers. I
rate them low as compared with monkeys, carnivores or even
elephants.

The Even-toed Ungulates have a still shorter duration of youth in
proportion to their size. Those that do not ruminate, the hippo-
potamus and the swine and peccaries, have often bred in captivity,
and we have therefore accurate information about them. The
hippopotamus is a very large animal, a good male reaching over
14 feet in length and weighing well over 4 tons. They are fully
adult in five or six years, although they may continue to increase
in bulk for some time after that. Swine of different kinds come to
maturity in from eighteen months to two years, although they also
may continue to increase in size for a longer period. The hippo-
potamus is certainly a stupid animal, and I do not believe in the
intelligence of pigs. The tricks of trained animals, such as the
46 CHILDHOOD OF ANIMALS

learned pigs of country fairs, are very simple adaptations of their
natural instincts, and are no evidence for the existence of any real
mental capacity.

The Ruminating Ungulates without exception have a very short
duration of youth in proportion to their size, and could be arranged
in an almost regular series in which size and duration of youth were
parallel. Giraffes are the largest, and their period of youth lasts
from six to seven years. Camels are adult in three years, llamas
and alpacas in rather less. Domestic cattle are adult in about two
years. Bison take between two and three years, and increase in
size for rather longer. The very large deer like elk are adult in two
years, but may continue to increase in size for a longer period; whilst
in them as in other deer, although there may not be much increase
in actual size, the antlers become more spreading and acquire
more points for many years after maturity has been attained.
Elands, which are the largest of the antelopes, are mature in three
to four years. Many of the little duikers reach their full size and
are adult in about twelve to eighteen months. The range of the
period of youth in the whole group of ruminants lies between seven
years and one year and follows the size of the animal rather
closely. It will be generally agreed that ruminants are animals of
low intelligence.

We have not much information as to the duration of youth in
the marsupials. The large kangaroos leave the pouch of the mother
permanently in from six to seven months. They grow very quickly
immediately afterwards, and are fully adult in from one to two
years. The smaller forms develop still more quickly and are
fully adult in from six months to a year.

Rodents differ much in size and in intelligence. Beavers are not
the largest members of the group, but they are larger than most, and
much more intelligent than any of the others. They begin to pair
when they are two years old and are fully grown at the end of
the third year, so that the duration of their youth may be reckoned
as being between two and three years. Hares may begin to breed
when they are a year old and are fully grown in fifteen months.
Rabbits have a shorter youth ; they pair when they are from five
to eight months old, and are fully grown in a year. Guinea-pigs
may begin to breed when they are three or four months old and are
full grown in from five to six months. Rats, which are born naked
and blind, are covered with hair on the eighth day, and are able to see
on the thirteenth day. On the twenty-first day they have reached
DURATION OF YOUTH IN MAMMALS 47

the size of a house mouse, and are turned out to shift for themselves
when they are thirty-nine days old. They begin to breed when they
are less than six months old and are fully grown a few months later.
Mice will breed when they are six weeks old and are fully grown at
three to four months old.

I do not think that it is necessary to go on giving any more
examples. It is clear that different kinds of mammals pass through
very different periods of time in growing to adult life. There is
certainly some relation between size and the duration of youth.
On the whole it takes a longer time to grow into a big animal than
into a small animal. But the relation is not so close that it can be
explained in a simple fashion. The youth of civilised man and of
the elephant lasts about the same number of years. A common
monkey and a lion take about the same time to grow up. The North
American beaver and the bison take very nearly the same time,
although the latter is several hundred times the bulk of the former.
Nor is there any part of the processes of nature which might lead
us to expect an inseparable link between time and bulk. The
different cells and tissues of the individual body grow at different
rates, and these rates may change at the call of circumstances that
have nothing to do with size. Temperature, moisture, the nature
of the food and many other agencies alter, retard or accelerate the
pace. There seems to be a very wide range within which the same
organs and tissues or the same kinds of animals or plants may grow
more quickly or slowly. None the less, it is reasonable to suppose
that closely allied animals have more or less similar constitutions,
and such a conclusion is supported by many physiological obser-
vations. They have similar habits, they react in similar fashions
to the same diseases, and betray their community of blood by
responding to similar environments in similar ways. And so com-
parisons between the duration of youth and the size of the adult are
less misleading when they are made inside the various groups.
I have shown that on the whole the larger animals of a group take
longer to grow up than the smaller animals of the same group.
But the parallel is not exact, and there are many exceptions, as, for
instance, among the Carnivora. On the other hand, the higher,
the more intelligent members of a group are usually the larger
animals. Here again there are exceptions, but on the whole it is
true of living groups and of the total procession of life in the past.
Mammals form the highest class of living animals, and amongst
mammals are to be found the largest existing members of the animal
48 CHILDHOOD OF ANIMALS

kingdom. In the age of Reptiles, when they were the lords of
creation, the largest existing animals were reptiles. In the age of
Batrachians the largest existing creatures were batrachians. And so
inside the orders of living mammals, they are, on the whole, the most
highly organised creatures that have been able to increase in size.
Certainly there are many advantages in being big. A bulky animal
can resist changes in temperature better than a smaller creature,
which may be more quickly overheated or chilled through. A big
animal, other things being equal, is more powerful and can protect
itself better and travel greater distances than a smaller animal of the
same kind. But there are also great disadvantages. A big animal
needs more food than a smaller one, and can less easily escape
the observation of its enemies. The struggle for existence is
specially keen among animals with similar habits and structure,
and amongst these it is the more highly organised and intelligent
that can become large with least risk. Amongst mammals I do
not doubt but that the apparent connection between the duration
of youth and the size is secondary ; both depend on intelligence
It is the more intelligent animals that have the longest period of
youth.

In the beginning of this chapter I spoke of the lengthening of the
period of youth in our own case, even in our own time. Breeders
of domesticated animals have found that they can prolong or shorten
the duration of youth in the case of farm stock. There are many
instances showing that wild animals in captivity mature more
quickly in some cases, more slowly in other cases, than their fellows
under natural conditions. The series of animals in the different
orders of mammals show that there is an increase in the duration of
youth as we pass from the lower forms to the higher forms. Putting
these different sets of observations together, we must draw the conclu-
sion that the rate of growth in animals has been altered in the course
of evolution, and in sucha fashion as to prolong youth in
the higher forms. This lengthening of youth is not completely
explained by increase of size, nor even by increased complexity of
structure. Its advantage is that it gives the opportunity for education
in the widest sense of the word, a space for experiment and for the
replacing of instinct by intelligence.
CHAPTER IV

THE DURATION OF YOUTH IN BIRDS AND
LOWER ANIMALS

BIRDS show Nature in her most luxuriant and inventive mood.
There seems to be an infinite variety in size, habits, disposition and
colouring, and yet these many differences conceal a similarity of
structure so close that there is a smaller gap between the ostrich
and the humming-bird, or between the flamingo and the wren, than
exists between many members of the same order of mammals.
For our present purpose they may be considered as a single group,
without reference to the divisions into which systematists have
been able to place them. I have already said that attempts have
been made to find some relation between the duration of the period
of youth and the whole life. Such attempts would fail completely
in the case of birds. It is a curious fact that in proportion to their
size, birds are longer lived, or at least have a higher potential
longevity, than mammals. If we compare them, group by group,
mammals are much larger than birds, herbivorous mammals than
herbivorous birds, frugivorous mammals than frugivorous birds,
omnivorous and carnivorous mammals than omnivorous and car-
nivorous birds. And yet, group by group, birds approach or
surpass mammals in longevity. Passerine birds, which range in
size from minute creatures which, stripped of their feathers, are no
larger than the tiniest shrew-mouse, to the large ravens, have a
potential longevity ranging from twenty to sixty years. Owls and
parrots certainly can live for half a century, and eagles and vultures
much longer. Pelicans and storks may live for from fifty to thirty
years, ducks and geese much longer, pigeons and gulls for thirty
years, ostriches for fifty years. Compared with these figures the
duration of youth is always short, and ranges from about two to
three or four years. Ostriches, which are the largest living birds,
take from three to four years to become full grown and adult, but
birds-of-paradise take nearly the same time. Condors and the
larger birds-of-prey are as big as a hen when they are a month old,
but take rather more than three years to reach their full size. The
C.A, 49 D
50 CHILDHOOD OF ANIMALS

smaller birds-of-prey, such, for instance, as turkey-vultures, are
full grown at two years old. Fowls and pheasants are full grown
at the end of their second year, whilst flamingoes, which are much
larger birds, take less than two years to become adult. The dura-
tion of youth in birds is therefore remarkably constant ; it varies,
from about one year to nearly four years. There is very little relation
between size and the length of youth. As the intelligence of
birds is very remote from that of our own, it is most difficult to
estimate which are higher and lower in this respect. But on the
whole it must be said that birds are much more instinctive than
mammals, that their various duties are performed in a more rigid
and mechanical fashion, and that there is therefore less scope than
amongst mammals for the experimental period of youth.

Reptiles live to great ages. They grow very slowly and
many of them appear to go on growing throughout their lives,
Although there are considerable differences in size between different)
adult individuals of the same species in both birds and mammals,
on the whole it may be said that each species has a rather precisely’
limited range of adult size, and that individuals outside the limits
of this range are abnormal—in fact, are dwarfs or giants. The
dimensions of the skull or of the body in adults are often so much
alike in a large number of individuals that they are useful characters
in defining and identifying species. This is not the case with
reptiles. No doubt there are limits beyond which crocodiles or
pythons do not grow, and there are large lizards and small lizards,
large serpents and small serpents. But as compared with birds
and mammals, the different species have not a fixed size. The rate
of growth, moreover, is much more dependent on surrounding
conditions, particularly on temperature. Birds and mammals have
an automatic system of regulating the temperature of their bodies.
In our own case, our normal temperature of 98.6° remains nearly
constant whether we are exposed to the cold of winter or the heat
of summer ; if it goes up a degree or goes down a degree we feel
uncomfortable, and if we found it to be I00° or 96° we should
know that we were ill and that there was some disorder interfering
with the routine of our physiological processes. So also each kind
of bird and mammal has its normal temperature, not quite so
stable as that of man, but during health kept fairly constant.
Reptiles, on the other hand, like batrachians, fishes and probabl
most, if not all, invertebrates, have not a normal temperature, but
go up and down with the temperature of the air or water with
YOUTH IN BIRDS AND LOWER ANIMALS 51

which they are surrounded and are thus almost at the mercy of
the elements. Ifthey become too hot or too cold they first get torpid,
and if the conditions continue they die. Reptiles will not feed or
grow unless they are kept warm. In the Reptile House of the
London Zoological Gardens the heating apparatus was greatly
improved in the year 1911; the reptiles were much more lively and
active, and the rather unexpected result occurred that the food
bill was nearly doubled. In the varying conditions of nature, a
succession of warm seasons or of cold seasons must affect the rate
of growth of reptiles to a very large degree, and it is not surprising
that we can tell little of the age of any individual from its size. Very
few reptiles breed in captivity, whilst in the wild condition their
shy habits make it difficult to observe them closely. There is the
further difficulty that young reptiles from the first are remarkably
like their parents. And so it happens that we have practically no
information regarding the duration of youth in reptiles.

The sizes to which the different species of frogs, toads and newts
may reach vary within wider limits than those of birds and mammals,
but it is curious that the range is narrower, especially in the case
of the tailless land forms, than occurs with reptiles. Batrachians
are less shy in their breeding habits than are reptiles, and many
of them have been bred and reared in captivity. In the case of
those that breed in water and pass through a metamorphosis, the
spawn is usually laid very early in the year, but this depends
partly on temperature. In cold seasons it may be delayed for some
weeks, and in England, except at considerable levels above the
sea, it usually occurs early in March. I have found the spawn of
the common grass frog in mountain bogs in Scotland late in June.
The tadpoles of the common frog begin to leave the eggs in about
five days, and in about two months the legs have appeared, whilst
the metamorphosis is complete and the frogs leave the water in
neatly three months. The development of the common toad is
not quite so rapid. The tadpoles leave the eggs in about ten days,
but the two pairs of limbs are not fully formed for about eighty
days, whilst the young toads leave the water relatively smaller than
frogs, when they are a little more than three months old. They
may begin to breed long before they are full grown, but they take
from three to five years to reach the normal size. The possible
duration of their life is unknown, but they have so many enemies
that probably few have the luck to reach old age.

Fish, like reptiles, grow slowly and may live to great ages. In
52 CHILDHOOD OF ANIMALS

them, as in reptiles, although there are species which may reach a
large size and species the members of which are always small,
there is a very wide range of size for each species, and growth
appears to go on continuously throughout life. As in the case of
reptiles, the rate of growth varies with external conditions, partly
those of temperature, but still more the nature and amount of the
food-supply. In many fish there are annual ring-like markings on
the scales, and in others in the concretions found in the internal
ear, and known as otoliths, by which the age can be estimated, in
the same way as the age of a tree can be ascertained by counting
the annual rings of growth visible when the stem is cut across.
Experiments made by transferring marked fish from places where
the food-supply is scanty to places where it is abundant have shown
that the size of a fish cannot be taken as an indication of its age.
The eggs of fish take from about three to over a hundred days to
hatch out, but the time varies a good deal according to the tempera-
ture of the water. As a rule the eggs of smaller fish hatch more
quickly than those of larger fish, but a more important difference
depends on the size of the egg. Small eggs with very little yolk
hatch quickly, and the larve on their appearance are in a more
rudimentary condition. Those with an abundant supply of yolk
take longer to hatch, but the larve are relatively larger and more
highly developed. As cold water delays development and retards
the period of hatching, the larve usually appear when the water is
warm and when there is an abundant supply of the microscopic
organisms on which they feed. Growth is then rapid and in most
cases the larvee become transformed into small fish like the adults
in the course of their first season. The subsequent history varies
much in different kinds of fish. In those where the larve and the
adults live under practically the same conditions, the sexual organs
often mature next season, and although the fishes may be small,
their period of youth is over. Often there is a migration from
inshore water to deep water, to the bottom of the sea, or, in the
case of fresh water, from the shallow fringes of lakes or from upland
streamlets to deep water or to the lower parts of rivers, and the
change to adult life may take more than a season. In fishes where
there is a complete change of habitat the youth may be further
prolonged. The larve of the salmon, called parr or samlets, are
hatched in the spring in the fresh-water pools where the spawn has
been deposited. They remain in the rivers usually for about two
years, slowly losing their youthful uniform of red spots and dark
‘YOUTH IN BIRDS AND LOWER ANIMALS 53

bars and acquiring a silvery colour. In the spring of the third
year they go down to the sea as smolts, which display a much darker
and more mottled coloration than salmon. In the sea they
rapidly mature, becoming silvery all over and developing their
sexual organs. They then ascend the rivers to breed, and their
duration of youth is thus at least three years, although from the
great change of size, a smolt weighing only a few ounces and a
grilse four or five pounds, it has been supposed that the young
fish may remain more than a single year in the sea. The fresh-
water eels migrate to the sea to spawn and lay their eggs at great
depths. These hatch out into ribbon-shaped larve with very
small heads. These little fish have been known as Leptocephali
for many years, the different kinds of them receiving different
specific names before it was discovered that they were the larve
of different kinds of eels. The larva of the common eel, formerly
known as Leptocephalus brevirostris, grows rapidly until it becomes
about two and a half inches long, when it passes through meta-
morphosis and becomes transformed toa small eel, which, curiously,
is only about two inches long. These small eels leave the bottom
of the sea and come up towards the coast when they are about a
year old. They then enter fresh water, ascending the rivers in
great numbers, and at night migrating from stream to stream across
wet grass. They live for a number of years before they become
adult, the largest size to which the females attain being a little
over a yard, that of males being much less. Then the sexual organs
begin to develop, the process taking several months, during which
the eels cease to feed. They then migrate down to the sea, and
when they have reached deep water, probably more than a hundred
fathoms, spawning takes place and the eels die. This is a curious
instance, very unusual amongst vertebrate animals, but common
in insects where nearly the whole life of the animal may be occupied
by the period of youth. It seems to be the case that eels spawn
only once, and that however long they live, or whatever size
they attain, they must be regarded as still in the youthful period
until they have ceased to feed and have begun to spawn.

All the vertebrate animals have a structure not remote from our
own, a nervous system consisting of a brain and spinal cord, and
organs of smell, sight and hearing essentially similar to our nose,
eyes and ears. Amongst them we are on familiar ground, and have
some reason to suppose that we can interpret their mental operations
and emotions with a sympathetic intelligence. The bond is most
54 CHILDHOOD OF ANIMALS

close between us and the higher monkeys and gets more and more
remote as we pass through the various orders of mammals and
descend through birds to reptiles, and from them to batrachians
and fishes. Fear and anger, cowardice and bravery, dislike and
affection, the relations of individuals to individuals and of species
to species, may differ in quality and degree, but appear to be
essentially similar in kind in all these different sets of animals.
They are all in mental touch with their environment in the same
sort of fashion. I think that we must be right in interpreting the
phases of their life by the same kind of standards that we can apply
to our own case. The duration of youth in all is settled by no
invariable chain of organic necessity. It has no relation to the
duration of the complete cycle of life from birth to death. It is
linked with size, but only in an indirect fashion, most apparent in
animals most akin. It is linked much more closely with complexity
of organisation, so that the higher forms usually take longer to
mature than their near but lower relations. It is linked most
closely with intelligence, the more intelligent animals having
relatively longer youth. And as we pass downwards from intelli-
gence to instinct we find that the duration of youth shortens.

The case of the eel, where the adult life is only a very small
portion of the total length of life, is not so curious as the cases of
many insects. Among insects there are all gradations between
creatures which live only a few weeks and creatures which enjoy
life for many years. Insects, however, are very closely dependent
on temperature, partly indirectly because their food-supply often
ceases in cold weather, and partly directly because they become
torpid and die when their bodies are subjected to cold. The dura-
tion of life of most insects is limited to less than a year. The eggs
hatch out when the temperature has become sufficiently high, the
larve grow bigger, pass through their metamorphoses and become
transformed to the adult in the same season. The life of most of
the adults ceases when the cold of winter comes on, if it has not
been arrested sooner ; but the species maintains existence, either
because the eggs are laid in a position where they may lie dormant
until next spring, or because a few of the adults hibernate in some
sheltered place. Sometimes the total life is limited to a very short
part of a single season. In many of the plant-lice, for instance, the
little green flies which plague the gardener, the total life lasts only
two or three weeks. The eggs are laid, the larve are hatched,
mature, become adult, and die all within a month. The total life
YOUTH IN BIRDS AND LOWER ANIMALS 55

of common flies such as the blow-fly and the house-fly is a little
longer. The blow-fly hatches out in twenty-four hours, the larva
takes a fortnight to grow, whilst the metamorphosis within the
pupa case takes a fortnight in warm weather, and much longer
when it is cold. The normal life of the adult fly is from a few days
to a few weeks, or in specially favourable circumstances, a few
months. The length of the larval life of butterflies and moths
varies according to the size, the habits and the weather, and as in
extreme cases the life of the adult may last a good many months, it
is possible that the total cycle may sometimes extend a little over a
year. Amongst bees, the larval life and the metamorphosis occupy
at most a few weeks, whilst the life of the adult is relatively longer.
Worker bees never live beyond the year in which they are produced ;
whilst the life of drones may be only a few days, and is never more
than a few months, as towards the end of the season, when honey is
getting scarce, they are driven out of the hive to perish. Queen
bees may live from two to five years ; they are fed and cared for by
the workers, and their confinement to the hive after the nuptial
flight preserves them from the vicissitudes of the weather.

The instances that I have given do not show any great eccentricity
in the distribution of the total duration of life between the youthful
and the adult stages. The proportion between the duration of
youth and of adult life certainly varies, but not much more than it
varies in higher animals, and we do not know enough about the
physiology of insects to assign reasons for these different durations,
and still less are we able to draw parallels between the lengths of
the period of youth and the degrees of intelligence. The mental
processes of insects and their modes of communication with the
exterior are so unlike our own that our attempts to discriminate
between instinct and intelligence must be the most casual guesses.
In very many insects, however, the disproportion between adult
life and larval life is so great that adult life appears to have been
reduced merely to the time required for reproduction. Many adult
moths and butterflies have no mouths and do not feed. The males
live only long enough to meet and fertilise the other sex, and the
females live a little longer, apparently only because they have to
seek out food-plants or places specially suitable for the larve which
will hatch out from the eggs they lay. The eggs of the mayflies
are dropped into the water and in a few months hatch out into
creeping campodeiform larve. These live, according to the species,
from six months to three years in the water, and then come up to the
56 CHILDHOOD OF ANIMALS

surface, usually creeping out on the banks. The larval integument
then splits open and a creature which has the form of a winged
insect and seems able to fly emerges. This, however, goes through
another moult, generally within a few minutes or hours of the first
moult, and the perfect insect appears and takes to flight. Its
mouth-organs are rudimentary and it is incapable of taking food,
and dies generally three or four hours after its emergence, in this
brief space of time having met the other sex and performed the
duties of reproduction. Dragon-flies similarly lay their eggs in
water ; the larve live from one to two years, and then, coming to
the surface, go through metamorphosis. The perfect insects are
predaceous creatures with powerful jaws ; they hawk and devour
smaller insects, but the total duration of their adult life is at most
a few months. In many beetles the disproportion between the
duration of youth and of the adult is still more remarkable. The
larve of longicorn beetles are vegetarian, burrowing in the bark or
wood of trees. Mr. C. J. Gahan has related a remarkable case under
his own observation. In May 1890 Captain Ernest Blunt, R.E.,
brought one of these larve to theBritish Museum. The larva was in a
boot-tree which he had had in use for fourteen years, seven of which
had been spent in North-West India. The larva was transferred
to a piece of beech-wood forming part of a museum stand, and lived
there until May 1895, when it was transferred to a fresh piece of
wood; it died shortly afterwards. Mr. Gahan has told me of
another case. Mr. Walter Rose, of Ilford, sent to the Museum in
September 1910 the wooden base of a bronze ornament which he
had had for just five years. It was one of a pair given him, but he
was unable to find out where it had come from. Two longicorn
beetles of a South European species emerged from the wooden
base a day or two after it had been received at the Museum. That
gave five years certain with some unknown period in addition for
the life of the larve. The exact duration of the life of the adults
is not known, but certainly is very much shorter than that of the
larve, usually not extending over the first winter after emergence.
A still more extraordinary case is that of the seventeen-year cicada,
a North American land bug. The adult insects are heavily built
creatures nearly an inch and a quarter in length, with two pairs of
transparent wings. The mouth-parts are imperfect and the creatures
do not feed, living only two or three weeks. The eggs are laid in
slits cut in the bark of trees, and the larve, soon after hatching,
burrow into the ground, where they live on vegetable matter. They
YOUTH IN BIRDS AND LOWER ANIMALS 57

grow slowly, moulting five or six times in the first two years of their
life. In the seventeenth year they leave the ground, burrowing up
through the surface soil or through hard-trodden paths, and after
hiding for a time under stones and sticks, crawl up trees, where they
undergo the final moult, from which the perfect insect emerges.
These various cases of the shortening of the adult life until it
leaves time only for reproduction must be secondary adaptations,
for it cannot be supposed that creatures with the elaborate structure
of winged insects could have come into existence without the
capacity to feed, and the extreme instances are connected by a
chain of intermediate forms with insects possessing a more normal
balance of the periods of life. Winged insects have many enemies ;
they are fed upon by all manner of reptiles, birds and mammals.
Weismann has suggested that the pressure of the struggle for
existence is so great that it has become of importance to them to
get through the business of reproduction as quickly as possible, and
that those insects have survived best and so have been favoured
by natural selection in which sexual maturity most quickly followed
the attainment of the adult form. In the extreme cases where the
insects became capable of reproduction immediately after their
final moult, and where little or no time had to be spent in choosing
suitable places for the eggs, it became unnecessary for the adults
to feed, and so their mouth-organs degenerated. This certainly
provides a reasonable explanation as to why the laying of eggs
should be hurried, for it is plain that the species would soon die
out if most of its adult members were killed off before they had
had time to lay the foundation of the next generation. It is a little
more difficult to understand, however, why the insects should die
so quickly, even although they have accomplished their task of
reproduction. Weismann suggested that this too was the result
of natural selection ; he supposed that it was an advantage to a
species to be represented by as many fresh and vigorous forms as
possible, and that just as a gardener removed faded flowers from
his floral borders and replaced them by younger and more vigorous
plants, so death came to weed out animals that had been battered
by the accidents of life, as quickly as possible after the maintenance
of the species had been secured by reproduction. He suggested,
further, that every animal was wound up, so to speak, only to
live for the time necessary to fulfil its cycle of life, and when
that had elapsed, the vital processes of repair and of removal
of wasted tissue which must continue to operate so long as an
60 CHILDHOOD OF ANIMALS

Mexican axolotl (Fig. 19). These animals occur in large numbers
in lakes near Mexico City, where they form an important article of
food. They are dark-coloured, tadpole-like creatures which when
fully grown are seven to nine inches in length, and possess a swim-
ming tail with a fringing fin above and below, with the usual two
pairs of limbs with fingers and toes, and with three pairs of gills
projecting from the sides of the neck. They are quite hardy, and
are familiar objects in aquaria in Europe, where they breed freely.

 

    

   

geal
Fic. 19. Metamorphosis of Axolotl. Upper figure, the aquatic
axolotl; lower figure, the terrestrial amblystoma,

     

They were supposed to belong to the division of batrachians which
are known as Perennibranchiata, as they retain their gills and the
aquatic habit throughout life. In 1865, however, some young
axolotls, bred in the Jardin des Plantes at Paris, gradually lost the
gills and the fin along the back and tail. The gill-slits closed up,
the head became broader, and the animals left the water perma-
nently. The black skin became blotched with spots and streaks
of yellow, and it was soon recognised that a metamorphosis had
taken place, that the axolotl was not an adult perennibranch, but
the larval form of a well-known salamander, Amblystoma tigrinum
(Fig. 19). A German lady, under the direction of two professors
at the University of Freiburg, proceeded to make a set of careful
experiments, and found that it was possible to induce young axolotls
YOUTH IN BIRDS AND LOWER ANIMALS  6r

to change into the adult amblystomas, the most successful method
being to keep them in very shallow vessels so that they had a
frequent opportunity of breathing air, and at the same time to make
the normal gill-respiration inconvenient by securing that the water
should have less than its proper quantity of dissolved air.

The curious facts as to larval reproduction in the axolotl throw a
possibly new light upon the relations of the different groups of
batrachians to each other. It had been assumed that the Perenni-
branchiata, those which remained aquatic and had gills throughout
their life, were the representatives of a primitive stock, and that in
the same way the gilled larve of the terrestrial adults represented
an ancestral stage passed through in the actual development of the
modern forms. It is clear, however, that the external gills do not
correspond with the primitive fish gills, and that the limbs with
fingers and toes correspond with terrestrial rather than aquatic
conditions. If the occasional metamorphosis of the axolotl had
not been discovered, the axolotl] would have been classed with the
other perennibranchs. It is quite probable that the other perenni-
branchs are creatures which have actually permanently lost their
terrestrial adult condition, and so are degenerate rather than
primitive. It has been suggested even that the ancestors of the
living batrachians were terrestrial creatures, breathing by lungs
and with two pairs of limbs with hands and feet possessing fingers
and toes, and that the aquatic larve with their external gills were
new interpolations in the life-history. If such a theory were
justified, then the perennibranchs, instead of being an ancestral
set of batrachians, would really be more modern than the terrestrial
forms, and their greater simplicity would be due to the loss of the
adult stage.

The progress of evolution is not invariably associated with advance
in structure, and it is quite possible that some of the groups which
we now think of as being primitive and as possibly representing
ancestral stages in evolution are merely larve, to which the power
of reproduction has been shifted backwards, and which in consequence
have permanently lost their adult stages. From this point of view
the curiosities of youth which I have been describing would have
a great importance in the theory of evolution.
CHAPTER V
COLOUR AND PATTERN IN ANIMALS

IT very often happens that young animals, even although they may
closely resemble their parents in structure, wear liveries with
different colours and patterns. A full-grown lion (see Plate III)
is nearly uniformly brown; his coat is rather paler on the
under parts, and his mane and tail-tuft may be tinged with black ;
and some individuals, especially lionesses, may show very faint
traces of spots. But lion-cubs are spotted animals. The American
tapir (Plate VI, p. 94) is very dark in colour, almost black all over
except for a white line round the edge of the shell of the ear; the
Malayan tapir is parti-coloured, the head, fore-quarters and legs
being black, but with a great saddle of white covering the hinder
part of the back and passing down under the ventral surface.
Young tapirs for the first two or three months of their existence
are vividly striped and spotted with white, and the pattern of the
Malayan and the American forms is almost identical. Red deer
are coloured almost uniformly reddish-brown, except for a light
patch or disc on the trump, but the young fawns are conspicuously
spotted (Plate V, p. 92). There are few living creatures so bril-
liantly coloured as the male birds-of-paradise. The head, back,
the upper surface of the wings and tail of the king bird-of-paradise,
for instance, are resplendent with a glow partly orange and partly
scarlet, and there is a breastplate of metallic green from which a little
bunch of brown feathers tipped with green hangs down at each side.
The chest and the lower part of the body are pure white, and the
long plumes which project from the tail terminate in shining tufts
of green rolled up so that they resemble the eyes on the feathers
of a peacock. The upper parts of young males are clothed with
sad-coloured brown, and their chests and under parts are banded and
mottled with a paler brown. Sea-gulls are brilliantly patterned
birds, the general effect being black-and-white, the chest and under
parts being white, and the head being covered with a cape or
mantle of black or dark grey. Young sea-gulls (see Plate VIII, p. 162)
62
PLATE III
LION, LIONESS AND CUB

Lion cubs vary in the extent to which they are spotted, and
the example shown is rather heavily spotted.
 

 

 
COLOUR AND PATTERN IN ANIMALS 63

are at first white, spotted with black and brown, and then covered
with a speckled coat of brown, excessively unlike the conspicuous
pattern of the adult. The king penguin (see Plate VII, p. 104) is
another brilliantly black-and-white bird, but its head, neck and
the upper part of the chest are tinged with orange and yellow. The
chick, even when it is as large as the parent, is covered with a
fluffy coat greyish-brown all over. The two sides of a young sole
or flounder are alike, pale grey in colour and studded with specks
of black. When the sole settles down on its side to its adult life
as a fish that haunts the bottom, the side which is going to lie next
the sand of the bottom becomes almost pure white, whilst the other
darkens and becomes much more spotted. I shall give many more
examples later on, but for the present it is enough to state that a
difference in colour and pattern between the young and the adult
is extremely frequent amongst animals.

Colour and pattern, or the combined result of colour and pattern
which is usually called coloration, are subjects that have attracted
the attention of naturalists from the earliest times, and before
discussing the special cases of young animals it will be convenient
to set down some general ideas on the matter. There is no side of
zoology that has been more fertile in producing theories ; many of
the greatest naturalists, and the lesser naturalists almost without
exception, have written on the subject, and I do not doubt but that
every person who will read these lines has made or will make
confident theories of his own. I hope, therefore, to proceed warily,
and to describe some of the most characteristic facts rather than
to select among the existing theories, or to provide a new one.
I shall begin, however, by a warning, specially necessary in trying
to interpret coloration. We must not scrutinise Nature too closely,
expecting to find a manifest purpose in all her variety. Reason
or cause there is for everything, in the sense that did we know the
complete chemical, physical and vital forces at work in the making
of any living thing, we should know that it must have this or that
pattern and colour and no other. But the factors that have brought
coloration into existence are separate, and must be studied separately
from the question as to whether the results are of any use or what that
use may be. We must free our minds from the idea that there is a
necessary and direct utility in everything we see. The diamond
takes no delight in its own shining, and there is no gain to the ruby
that it glows with a sullen fire, or to the opal that it quivers with
the lights of the sea at dawn. The red blood flushes the pale skin
64 CHILDHOOD OF ANIMALS

of a girl until it becomes a wonder and a delight, but it ran no less
red for countless generations under the thick and hairy hide of the
apes that were her ancestors. The little shining grains that we’
call pearls are diseases of the shell-fish in which they are formed.
Undoubtedly there is a reason for it, but who shall say that there
is a purpose in the males of the eclectus parrots being green whilst
the females are red? The truth is that living things must have
colour and pattern whether these be directly useful to them or no.

Even the untrained eye

ze oS yee Ps ot | “SS at once picks out fossils
* # in a slab of rock or

“AY TACs a= shells lying on the sea-
FA 2 them and identifies
them as having be-
ee to living things,.

&

= because their patterned
we ( (07 8 a 5) i 13 surface is in contrast
o a, with the formless mono-
6 ‘= TN ne of the surround-

ing matter. Pattern is

ww C7 EL a Ay essentially repetition of
arts. If we stand in

a hall of mirrors and
ef aes fr. look at the endless
\\+f ba i! , images of ourselves re-:
Fic. 20. Repetition ety a by tearing flected from mirror to
holes in a sheet of folded paper and then mirror we shall find
unfolding it.
that we and_ these:
multiplications of our body compose a pattern. Similarly in
the scientific toy known as a kaleidoscope, a few fragments of
coloured tinsel and glass are dropped into a cardboard tube with
a glass bottom surrounded by a circle of little mirrors. When we'
look through the tube against the light the duplications and’
reduplications of the fragments form an elaborate pattern which
changes into a new complexity as we revolve or shake the tube.
If we take a sheet of thin paper and fold it first into two and then
into four, then double it diagonally from the central corner, then
tear, however roughly, a few holes in the folded edges, we shall
find on unfolding it again that we have formed a symmetrical
pattern, radiating from the centre of the sheet (Fig. 20). If we
‘take another sheet of paper, fold it across so as to make a guiding
COLOUR AND PATTERN IN ANIMALS 65

crease along the middle, and then unfolding it, write a name in ink
with a thick pen along one side of the crease, then quickly fold it
over and press it down before the ink has dried, we shall find we
jhave made another kind of pattern (Fig. 21), this time not
xadially symmetrical round a central point, but bilaterally
symmetrical on the two sides of the crease, and more complicated
in detail because of the different thicknesses of the ink we left to be
doubled and the unconsciously different
pressures we gave when folding over the
paper on the wet ink.

The growth of every body takes place by
the multiplication of the little units we
know as cells, or of higher units composed
of masses of cells. Sometimes the multi- g
plication takes place radially and regularly,
or radially and irregularly, sometimes in a
bilateral plane, and this again regularly or
irregularly. And so all the tissues of the
body, microscopic or visible to the naked
eye, are patterned. In the simpler forms of
life and the simpler, most mechanical parts
of the body, the patterns are simple and
regular, to whatever system they may belong.
In the higher tissues and higher organisms Ox
the primitive numerical symmetries of re- Fic.21, Bilateral Pattern
petition are disguised by ordered irregu- eee men ea
larities in growth, now one part, now another words written were
part being retarded or accelerated, and by  “ Royal Institution.”
the interference of the growth-forces of one set of organs with the
growth-forces of another. If a drop of some oily pigment be placed
on water in a bowl it will spread out slowly in a ring-shaped pattern ;
if other drops be placed near it, as they spread they will interfere with
and distort the patterns already formed. If the water be made to
move slowly by stroking the surface with a brush or by blowing on it,
the systems of rings will spread out into irregular curved streaks,
forming the well-known watered or moiré effects used in textiles,
and sometimes seen on the paper lining the covers of books. Similar
patterns are very common in animal tissues, due to the growth-
forces being more intense in one direction than in another. Thus
ina multitude of ways patterns are formed in the tissues of animals,
as the inevitable consequence of structure and mode of growth, and

CB E

 
66 CHILDHOOD OF ANIMALS

the pattern, although inevitable and associated with structure
that no doubt is useful, is not in itself useful. We do not frame
explanations of its meaning and purpose when it is concealed
within the body and made visible only by dissection and the micro-
scope, but if it crop out on the surface and so is visible, then we
are disposed to imagine that it must have some special fitness for
the conditions in which the animal lives, and to speculate as to
how the conditions could have called into existence the pattern
that fitted them. I do not doubt that such inevitable growth-
patterns sometimes confer an advantage on an animal, and have
been maintained by the operation of natural selection, but it appears
to me that it is their absence and not their presence that requires
explanation, and that natural selection has been more effective in
smoothing out and obliterating the inevitable growth-patterns than
in preserving them, or being the agent in their formation.

All visible things must have colour, and so also it is inevitable
that animals must have colour. The colour may be due to one of
several causes or toa combination of causes. Many hues, especially
those with metallic sheen, depend on the structure of the surface
on which the light falls, the white light being broken up in the
process of reflection. When a piece of transparent glass or ice is
powdered it becomes white like snow, and this appearance is due
to the total reflection of the light from the mixture of little solid
particles and intervening bubbles of air. The white of animal
tissues is produced in this way. The fur and feathers of arctic
mammals and birds, white patches on the skin and so forth come
about because there are little bubbles of air or of some other gas
entangled in the structure of the tissue. The blues and greens of
many birds and insects which do not change in colour according
to the angle at which light is reflected from them, and the still
more vivid metallic iridescent colours which change as they are
moved about, and which are conspicuous in the eyes of the peacock’s
tail and in the bright tints of birds-of-paradise, are due to a combina-
tion of structure and pigment. Frequently there is a dark pigment
underlying a transparent layer, forming a kind of mirror, and the
play of colours comes from the varying incidence of light and the
varied sculpturing or thickness of the transparent layer.

Other colours may be due to the presence of pigments—that is
to say, actually coloured substances. Blues and greens occasion-
ally, reds, yellows, blacks and browns almost invariably are
pigmentary. The brilliant crimson of the feathers of the turacos is
COLOUR AND PATTERN IN ANIMALS 67

not only a pigment, but one that is soluble in soft water, and is
washed out in a heavy shower of rain. A less well known case is
that of the black colour of the Malay tapir. If the hand be rubbed
over the dark portion of the body a black, greasy stain comes off,
whilst the grey part of the body is devoid of this secretion. In
some of these cases, perhaps in most of them, the pigment has a
direct physiological importance, as, for instance, the red colour of
blood, due to the presence of hemoglobin, the substance which
carries oxygen to the tissues ; or some of the greens and yellows,
which are products of the chemical changes of the body, and are
waste matters on the way to be removed; or blacks, which also
not infrequently are products of excretion. I have already said
that the blood was red long before the colour became a visible
ornament of the body. So also the black lining of the body-cavity
in many reptiles, the brilliant greens and golden yellows of the
gall-bladder, the vivid green of the bones of fishes like the South
American lung-fish, are clear instances of strongly marked colour,
for which, were they visible externally, we should attempt to
find an adaptive explanation, to interpret in the light of suitability
to the surrounding conditions. Precisely as in the case of pattern,
we must not be too certain that colour has a direct purpose. Colours
may be useful, and often are turned to use, but their utility may
only be secondary, a laying hold of something that was already
there. All warm-blooded animals radiate out heat, varying in
amount with the physical activities of their bodies, with the
structure and disposition of their protective coverings and so forth,
and if we possessed organs as sensitive to heat as our eyes are sensi-
tive to colour and light, we should learn to recognise the presence
and perhaps the nature of animals near us by means of the messages
that such a heat-sense would convey to the brain, and the heat
diffusion of the animals themselves might have been turned to
account for their own purposes. When small birds are roosting
in the open air on a cold night they fluff out their feathers until
the bodies become almost globular, and by so doing they retain
more of their internal heat. In such a condition they would be
unnoticed by a heat-sense at a much greater distance. They are thus
accidentally protected against a danger that does not exist. And
so it may be with some of the colours of animals.

Finally, the presence of colour, whether it be due to structure or
to pigment, makes pattern more conspicuous, while the existence
of pattern calls attention to differences of colour. When micro-
68 CHILDHOOD OF ANIMALS

scopists are examining the structure of animal tissues, one of their
difficulties is that the pale grey tone of the material they are investi-
gating is almost uniform. And so they have learned to treat it
with various dyes, some of which make the differences in structure
visible merely because certain parts stain more deeply than other
parts, whilst invisible chemical differences become visible by the
parts of the tissue accepting, refusing or changing the colour with
which they are bathed. And as the red blood shining through the
pale skin suffuses the surface with tints of different intensity, so
the pigments which are being excreted through the skin become
differently entangled in different parts of the structure, make new
combinations of colour chemically or physically, and the varied
structure itself shines differently under the same beams of light.

Colour, pattern, and the combination of colour and pattern that
we call coloration are to be expected everywhere in the animal
kingdom, as indeed in the living world. They are the visible
expression of the complex nature and of the mode of growth of
living things. All organisms increase in size by the multiplication
of parts, and the simpler they are the more mechanically geometrical
we must expect them to be. As they become more complex in
structure, the primitive and yet more startling symmetry of their
patterns becomes altered by irregular growth, by excess in some
parts, retardation in others, and by interference of the growth of
different systems or centres. Structurally every body is a mosaic,
but it is a mosaic which has grown by the growth and multiplication
of the separate pieces at different rates. It must have pattern.
The different pieces and systems of pieces must have colour, and as
they become different in their functions, inherent differences in
colour, and differences due to different reactions to the coloured
fluids and substances that pervade the whole, cause a still greater
diversity. And so coloration is an inevitable outcrop, which may
or may not be useful.

And now, having fenced the tables, we pass to consideration of
the uses to which colours and patterns may be put and of the ad-
vantages they may confer on their owners, with a clear conscience.

In natural history all general rules are dangerous, but there is
none safer than that it is seldom an advantage to an animal to be
conspicuous. It is a hungry world, and there is nothing more
generally useful than not to attract attention. The lowest grade in
the evolution of ccloration is when pattern that is the direct
expression of structure and colour—that is to say, the direct result
mers:

- PLATE IV
- LADY AMHERST’S PHEASANTS

Cock, hen and chicks. The drawing is not an exact colour

diagram of the species, but gives the general effect of the

coloration, and the contrasted patterns of the sexes and
: the ‘young.
 
COLOUR AND PATTERN IN ANIMALS 69

of the chemical processes of the body—is retained. This grade is to
be expected in primitive animals and in the young stages of animals,
and, whether it be brilliant or dull, is retained in higher types when
It is not disadvantageous. The second grade is the smoothing over
and partial obliteration of growth-pattern and the toning down of
natural colours. This condition is the simplest mode of producing
concealment by inconspicuousness, in conditions where the first
grades of colour and pattern are disadvantageous. The third and
highest grade is when the structural pattern is overlaid by a new
pattern, often with very little relation to the natural growth and
symmetry of the animal, and where the colours do not appear to
be the direct result of the ordinary physiological processes of the
body. This third grade is found in the higher groups of animals, and
is more frequent in adults than in the young, and in males than in
females. As we shall see, even although it may be vivid and brilliant,
it may yet secure inconspicuousness in the natural environment of
theanimals. These three grades must be taken as a help to remember
and understand coloration, and not as an absolute set of divisions
into which the facts fall, or into one of which any particular fact can
be placed with complete certainty.

As the cases in which it appears to be an advantage to animals to
be conspicuous are relatively few, I shall begin with them. Many
animals, and especially males, wear their bravest livery as a marriage
dress, and however they may be colourea at other times, are
resplendent at the approach of the breeding season. Differences
in coloration of the sexes are not frequent amongst mammals,
although the males are more usually distinguished by their powerful
weapons of aggression. But the coloured patches on the skin
in many monkeys are brighter and more conspicuous in males,
and differences in colour and pattern mark the males of many
deer, antelopes and small carnivores. These male ornaments
are usually intensified during the breeding season. In birds
such differences are almost the rule, and are directly associated
with the breeding season, which in many cases is preceded by
a moult, after which the sexual plumage is assumed, or the colour
of the naked parts intensified. Every one knows that the
cocks are most highly ornamented in such familiar examples
as the fowls and pheasants (see Plate IV), the peacocks, drakes,
male ostriches, birds-of-paradise, and so on. But there are also
birds in which the sexes are so much alike that it is almost
impossible to distinguish them except by observation of their
70 CHILDHOOD OF ANIMALS

habits, as in the case of pigeons, partridges, most parrots, owls,
birds-of-prey, and many of the small singing birds. There are even
a few odd cases where there is a conspicuous difference in colora-
tion and the females are the more resplendent. This happens in
phalaropes, some button-quails, painted snipes and cassowaries, and
it is curious that in these cases the usual disposition of the sexes
is reversed, and the females are pugnacious, aggressive and courtiers
of the males. The sexes are usually alike in reptiles, but male
lizards may be brightly coloured when the breeding season
approaches. Amongst batrachians there are many in which the
sexes are alike, but male newts assume a brilliant nuptial colora-
tion. Whilst the males and females of most fishes are alike in
colour, there are many well-known examples of males becoming
more brilliant in the breeding season. Butterflies, moths, beetles
and bugs, and dragon-flies may be clad in sober or gaudy tints, and
are frequently alike in the two sexes, but where there is a difference
it is almost invariably the male sex that is conspicuous. In spiders,
again, the males are not infrequently more brightly coloured than
their mates. The interpretation of such sexual coloration is very
difficult. In some cases, especially those of insects where the
sexes are alike, bright colours belong to some other category of
coloration, or, as Darwin suggested, may have been acquired in
one sex and then transmitted by inheritance to both sexes. In
other cases they may be the mere expression of exuberant vitality,
of active physiological processes, and may be of no special utility
so far as the attraction of the sexes is concerned, but may have
been retained in the brilliantly coloured males because their presence
was not disadvantageous, and suppressed in the dull females where
it was of advantage to the next generation that the female should
be inconspicuous during her laying of the eggs and guardianship of
the young. But there remain a large number of cases where one
sex, almost invariably the male, is always conspicuous during the
breeding season, whether that occupy the whole adult life or be a
recurrent episode. In such cases it certainly seems to be an advan-
tage to the male to be conspicuous, and there is no better interpreta-
tion of these facts than that given more than forty years ago, with
the most judicial reticence, by Charles Darwin in the ‘“ Descent of
Man and Selection in Relation to Sex.” Darwin showed that
in very many cases where the males were conspicuously coloured,
they flaunted their colours and patterns before the female, excited
her attention by them, and gave her the opportunity, consciously
COLOUR AND PATTERN IN ANIMALS 71

or unconsciously, of preferring the most vividly marked. Sexual
conspicuousness, however, is a subject which does not specially
concern young animals, and it would be outside the purpose of
this book to discuss the theory of it at length. But it is interesting
to notice that where adult males are specially conspicuous, so differing
from young males and females, the latter usually resemble each
other and together resemble more primitive forms. This seems
to suggest that the sexual coloration is an instance of my third
grade of coloration, and is a relatively late acquisition, a thing
imposed on the more primitive patterns and colours. It is to be
noticed also that in a great many cases sexual coloration does not
conform with the growth and structural lines of the body, but has
much of the character of an artificial addition.

It is quite possible that females may not exercise a conscious
preference in favour of conspicuous males, and that none the less
the conspicuous pattern is of advantage in attracting her attention.
The sexes find each other in many ways: by call-notes, by scents,
by coloration. I have been watching this afternoon the familiar
display of the males of two of the beautifully coloured pheasants.
The Peacock pheasant kept strutting round to face the hen, and
then stopped in front of her, hiding his dull-coloured breast but
showing the white tuft that hangs over his forehead in the breeding
season, raising and expanding the wings with their rows of blue
“eyes,” and holding the tail erect and expanded, with the rows of
large green eyes shining in the sun so that the whole bird was a
gorgeous mass of spangles. The Amherst cock ran round the hen,
exhibiting himself sideways, raising the wing farthest from her,
depressing the one nearest her, and twisting the tail sideways so as
to show the greatest part of its coloured upper surface. The hens
in both cases were at first indifferent or reluctant, but the glittering
expanses of feathers soon excited their attention. So also brightly
coloured male butterflies mob a female, fluttering round her and
showing off to the best advantage; whilst male spiders dance in
front of the females in such a fashion as to show off their colours.
Even if such decorations are no more than outcrops of structure and
surplus physiological activity, they are used to attract the attention
of the females and possibly to excite them.

Conspicuous patches of colour, like sounds and scents, may be
useful as recognition marks, especially amongst gregarious animals,
or where the young follow the mother. Notable instances are the
yellow or white patches on the rumps of many deer and antelopes,
W2 CHILDHOOD OF ANIMALS

which stand out conspicuously against the general brown coloration!
of the body; whilst the white, erect tails of rabbits and other
small creatures that run in single file in the dusk along special
tracks may well serve as moving sign-posts.

The most common case of the utility of conspicuous coloration
is when that serves to advertise an animal to its enemies, so that
it may be easily seen, easily remembered and avoided in future.
It is plain that such an advertisement is of little use unless it be
associated with the existence of an unpleasant or dangerous property,
such as nasty flavour, bad odour, power of stinging or of giving
poisonous bites. The advantage is either to the individual animal or
to the species, or to both. It is useless for a snake to have to strike
its poison-fangs into an animal that is too big for it to eat; it is
worse than useless, for the process exhausts the poison glands
temporarily and puts them out of action so that they cannot be
used for some time for the purposes of the snake, whilst there is
always a chance of the snake itself being killed and eaten by its
prey. And so bright colours, terrifying attitudes and noises, such
as hissing and rattling, are useful to the snake. Warning colours
are still more useful in the case of bees where the sting is left in
the wound and its loss kills the bee. Very many small animals
with evil odours, such as skunks, have patterns of vivid black and
white which are specially visible in the dusk, and it is supposed
that they can thus be recognised by carnivorous animals that
otherwise would kill them and then find themselves unable to eat
them. No doubt a few individuals would perish each season
whilst young carnivores were learning the lesson that such animals
were not worth the trouble of killing, but the species would gain.

Opinions differ widely as to the closeness of relation between
unpalatability and bright colours amongst insects, but after reading
through a considerable part of the very extensive and rather
pugnacious literature on the subject, I think there is a strong
balance of evidence in favour of the view first suggested by
A. R. Wallace to Darwin, that adult insects and caterpillars which
insectivorous birds and lizards find nauseous are extremely often
brightly coloured and conspicuously marked. Some of the most
striking negative experiments have been made on birds and reptiles
in captivity, and as these are frequently tame and accustomed to
take any food that is offered to them, it is not surprising that they
have been found to eat insects that are probably nauseous. Such
negative evidence is more than outweighed by the cases where
COLOUR AND PATTERN IN ANIMALS 73

they have either completely refused the subjects of experiment or
rejected them after tasting ; whilst the fact that brightly coloured
insects and caterpillars in their native haunts very seldom conceal
themselves is a cogent argument for the view that they are un-
palatable. It has been found, moreover, that young birds—and
no doubt the same is true of young lizards—have no instinctive
knowledge of which insects are not good to eat, and that they have
to learn by experiment. Such experimental tasting must be
disastrous to the individual subjected to it, but as insects and their
caterpillars usually occur in great numbers at a time, the species
gains, although some of its individual members perish.

Other cases of the possible utility of bright colour and conspicuous
pattern are grouped under the theory of mimicry. It is certainly
true that some animals without unpleasant qualities resemble very
closely, in their appearance and ostentatious habits, other animals
living in the same locality which have both conspicuous coloration
and some quality the possession of which it is useful to advertise.
The genuinely unpleasant creature is called the model, and the
creature resembling it is called the mimic, and it was supposed by
H. W. Bates, who first suggested this explanation, that the imitation

' of the model by the mimic was useful to the latter by deceiving its
enemies into the belief that they had to deal with an animal
better left alone. The most probable examples occur amongst
insects. Ants, because of their ferocity and their power of defence
and aggression by means of their biting jaws and venomous stings,
are very generally left alone by other members of the animal kingdom,
and are frequently closely imitated by harmless beetles and bugs.
The stinging bees and wasps are similarly imitated in coloration
and pattern by harmless flies. Many tropical butterflies and moths
that are known to be distasteful aze brightly coloured and show by
their habits and slow flight that it is not necessary for them to
avoid attracting attention. They are closely mimicked by other
butterflies and moths that are not distasteful.

It is plain that if such mimicry really bear the interpretation that
has been placed upon it, it can be effective only when the mimics
are less numerous than the models. Otherwise, in the process of
the experiments of young birds and other insectivorous creatures,
the lesson would be spoiled if the brightly coloured creatures were
as often harmless or tasty as otherwise. F. Miiller extended the
theory of mimicry to cover a further set of observations. He
showed that frequently a number of different species or kinds of
74 CHILDHOOD OF ANIMALS

armed or nauseous creatures inhabiting the same district were not
only conspicuously coloured, but resembled one another in the kind
of coloration. Obviously, in mimicry of this kind, there would be
very great economy, as each species of the group forming the
community of similarly coloured creatures would profit by the
lessons learned by tasting experiments made on individuals of any’
of the species. Thus the experimental death-rate, the toll paid by
the whole community, would fall less heavily than if it were limited)
to a single species ; whilst the local enemies would have to learn to.
avoid only one pattern instead of many patterns.

The theory of warning coloration and the associated theories of
mimicry have been attacked partly on the ground that there is
not enough experimental evidence to justify them, and partly on
the ground that the pattern and colour can be explained otherwise.
On the whole there seems to be enough experimental evidence to
justify the conclusion that there is a frequent association between
conspicuous coloration and unpleasant qualities on the part of
the models. It is, however, another matter to assume that the
coloration of the models or mimics has come into existence because
of its utility. The colours and patterns may be the natural out-
crop of the constitutions and modes of growth of the creatures in
which they are found; and if this be so, if in fact they belong to
what I have described as the lowest grade of ornamentation, it is
not surprising that they should occur in closely similar forms in
closely allied species. The recent experiments in breeding conducted
by naturalists who have been working on the lines suggested by
Mendel would seem to show that even very elaborate coloration
and extremely intricate patterns are produced inevitably in the
laboratory of the living organism. If this be so, the path is made
easier, and not more difficult, as some of Mendel’s disciples appear
to think, for those who wish to interpret colour and pattern in
terms of utility. It would no longer be necessary to try to imagine
an increasing utility with each small elaboration of pattern. The
coloration would be produced, so to speak, ready made, and would
be retained if it were useful, or perish with its owner if it were harmful.

There is no quality more generally useful to an animal than that of
being inconspicuous. The living world is a very serious game of hide-
and-seek, in which nearly every adult animal and those young ones
that are not hidden or protected by their parent must join. The
penalties are severe ; those that are caught are eaten, and those that
fail to catch starve. Animals may hunt their prey by scent, but
COLOUR AND PATTERN IN ANIMALS 75

there nearly always comes a critical final moment, when they must
be able to see the object on which they are to pounce. Animals
may escape by swiftness, but it is extremely useful if they are
so invisible that their enemy cannot easily follow them by
sight, and still more useful if when they are hard pressed, or
when they have reached a favourable spot, they can suddenly
fade into the background and become invisible. We all know
how difficult it is to see animals in a wood, or a heath, or on the
open plain, even when they are abundant; in chasing an animal
with net, or gun, or camera, we have all been baffled by the sudden
and almost incomprehensible disappearance of our quarry. We
are not surprised at the invisibility of animals with subdued
coloration, or animals clearly like their natural background, as, for
instance, a mottled-brown moth flat against the bark of a tree, or a
green caterpillar lying on a green leaf, and it is to such obvious
harmonies between coloration and environment that the name of pro-
tective coloration has been given. But Mr. Abbott Thayer has shown
so many instances where coloration that seems to us brilliant and
conspicuous really serves for concealment, when it is seen from the
point of view of the enemy or of the prospective victim, against
the natural background, that he has made it probable that nearly
every kind of natural coloration serves for concealment. Patterns
that we think conspicuous, and brilliant colours that we have tried
to explain as warning or advertising, or for purposes of recognition,
or as nuptial plumage, may really be for protective or aggressive
concealment.

There is no arrangement of shading so common in the animal
kingdom as for the upper surface to be darker than the lower surface.
Even in domestic animals we are accustomed to see the under parts
light or white in comparison with the back, although among these
the external appearance has been greatly changed, partly by the
conscious selection of man and partly because as these animals
enjoy human protection it is not so necessary for them to be
concealed from their natural enemies or their natural prey. But
in wild nature the dark shading of the upper surface and the
lightening of the lower surface seem to be almost the rule. The
contrast is visible even in the tawny lion and the striped tiger ;
jaguars, leopards and most of the smaller cats, however they may
be spotted or striped, show it. It is conspicuous in zebras, wild
asses, deer, sheep and goats and antelopes, in hares and rabbits,
in kangaroos, in whales and porpoises, in an enormous number of
76 CHILDHOOD OF ANIMALS

birds, in snakes and lizards, in frogs and toads, in very many fish,
whilst most of the creeping insects and their larve exhibit it.
There is no obvious difference in the structure of the body to account
for it ; the skin, fur, feathers or scales are formed in the same way
from similar materials all over the body, and the difference cannot
be explained as the visible expression of anatomical facts. Nor
can it be explained as being due to the direct action of sunlight,
for the most probable effect of intenser sunlight on tissues is to
bleach rather than to stain, and if there be a difference according
to habitat, the contrast is greater in many of the swarthy inhabi-
tants of forests than in natives of the open plains.

Although we do not know the physical cause of this common
pattern, Mr. Thayer has shown its advantage to the many animals
which possess it. Professor E. B. Poulton, of the University of
Oxford, had already shown how in some caterpillars the distribution
of light and dark shades destroyed the rounded appearance, and
made the plump bodies appear flat and not sharply marked off
from the food-plant on which they were resting, but Mr. Thayer
worked out the idea independently and showed how it applied on
a much larger scale. If a white billiard-ball be placed on a table
where it is lighted from above, or carried into the open air and
similarly exposed to the sky, it will be seen that it looks round and
solid chiefly because it is brilliantly white above where it is fully
lighted, and almost black near the surface on which it is resting,
because there it is in the shade, whilst between the two poles the
light and shade gradually pass into each other. Now the natural
disposition of light and dark colour on an animal is so arranged as
to counteract this result of natural illumination, for the dark shades
are found on the upper parts where the illumination is greatest,
and the light shades on the under surface where the illumination is
least. The natural pattern, in fact, is a counter-shading of the
natural illumination. It is not easy to get any pigment to adhere
to the surface of a billiard-ball, but if two rubber balls be taken
and one painted white all over, the other painted white on one end,
black on the other, and gradually shaded off to the equator, and
then the two balls be placed alongside where they are illuminated
from above, the effect will be seen at once. The white ball will
look round and solid, white above and dark below; the other ball, if
it be placed with the dark pole uppermost, will look flat, and almost
of an even grey tint all over.

In this way the plump solidity of the natural contours of an
COLOUR AND PATTERN IN ANIMALS 99

animal fades into a ghostly elusiveness against its natural back-
ground, especially when the light is rather diffused, as on a cloudy
day, or where a creature is lurking in a shadowy corner for its prey,
or tips and fades mto a covert when it is being pursued. A model
invented by Mr. Thayer and often exhibited in museums shows the
real invisibility conferred by counter-shading. Two bird-shaped
bodies are fixed on a rod that can be revolved, and are placed in
a case with a glass roof lighted from above, with the side next the
spectator open and the background and two other sides painted
with neutral grey. The body of one bird is painted all over as nearly
as possible the same shade as the background; the body of the
other is darkened above and made lighter than the background
below. At a little distance, the self-tinted model stands out clearly
from the background as the solid body of a bird, white above where
it is illuminated, dark below where it is in shadow; but the other
model is almost invisible, for the counter-shading neutralises the
effect of the illumination. If the rod on which the models are
fixed be rotated, the neutrally tinted body remains visible, whilst
the counter-shaded model, as its shading is now disposed so as to
agree with the natural lighting, becomes visible at once, being even
more conspicuous than the other.

So also if a white rabbit or hare, or a ptarmigan in its white
winter plumage, be placed in a similarly constructed case with a
white background, we shall see that the resemblance in colour to
the background does not protect it. On the other hand, if it be
seen in bright sunlight on a glistening surface of snow, the light
reflected up from the snow on the under surface of its body to a
certain extent counteracts the natural effect of light and shadow
and brings about a fair degree of invisibility. The polar bear
stalking seals at the edge of the ice probably enjoys a similar
softening of outline from reflected light. Desert animals may also
gain something from the light reflected upwards from the sand, and
in their cases the contrast between the upper and under surfaces
is slight. So also it is slight from another reason in animals that
haunt the interior of shady forests; such light as filters through
the trees is diffused and obscure, and the upper surface is only slightly
darker than the under surface. The contrast is greatest in those
animals that live on dark ground under the open sky, as in many
of the rodents, kangaroos and deer that live on open plains.

Counter-shading is a character that may be found in various
degrees of strength combined with many different kinds of colora-
78 CHILDHOOD OF ANIMALS

tion and pattern, the utility of which may be set down generally as
ways of matching the environment. In most of the desert animals
the various shades of sandy brown known as “khaki” and used
by modern armies for the purpose of concealment are the prevailing
tints. In insects that live on green foliage, the ground colour is
frequently a shade of green. In ground-haunting birds like snipe
and woodcock, which live among fallen leaves and sticks or in
weeds and grasses, the surface is blotched, striped and mottled in
irregular lines and patches, which resemble the usual background,
and which, with the addition of counter-shading, make an almost
perfect concealment. Especially in the plumage worn during the
nesting season by the females, the surface may present a very
elaborate picture of the leaves, sticks and stones, mossy trunks,
heather and so forth among which the females have to brood on
their nests, and if possible remain unnoticed by their carnivorous
foes, so that they may preserve their own lives and those of their
helpless young. The spotted coats of leopards and jaguars, and of
many deer, similarly match the natural background of light shining
through the interstices of foliage; whilst the stripes of the tiger
and of many of the antelopes suggest the effects of light and
shade thrown by tall reeds and thick grass.

The various forms of matching the background with which I
have been dealing are most successful when the wearers of these
liveries are at rest, and their utility is plainest in the case of animals
which have the habit of squatting on the ground, whether to await
their prey or to avoid their enemies. Familiar examples are the
brooding female bird, the hare squatting in its form on the open
ground, or the tiger crouching to spring. Another and more
interesting kind of protective coloration is most useful to males
displaying themselves before the females and with their attention
so engrossed that they are not on the watch for their enemies, or to
creatures in active motion in pursuit of prey or in search of food.
Such moving creatures come under different effects of light and
shadow, are now lighted up by the sun, now suddenly brought
against a light background or a dark background, and are under
conditions where any elaborate matching of details would be useless.
Some of the boldest patterns and brightest colours, combinations
that seem amazingly conspicuous in a cabinet or a museum, really
serve for concealment under the natural conditions. They break
up the natural outline of the animal, which would be otherwise
conspicuous by the uniformity of its shape against the irregularity
COLOUR AND PATTERN IN ANIMALS 79

of its surroundings. The great white patches on the hindquarters
of many deer and antelopes, which are sometimes expanded when
the creatures are excited, break up their outline when seen from
behind. The black-and-white markings on the head and face
and the curious reversed coloration of small carnivores like
badgers and skunks and ratels make them more conspicuous to us,
but when seen against the sky-line at dusk by the small prey which

  

Fic. 22. Oyster-catcher, showing counter-shading and
ruptive pattern.

they hunt, serve to make them invisible. The vivid black-and-
white patches of many shore birds (Fig. 22), the curious appendages,
the secant lines across the body, the odd markings of the
head so common in birds, serve a similar purpose. The strangest
and most violent patches of colour, the bright plumes, and the
shifting iridescences, all may help to dazzle the eye of victim or
enemy. We must always remember that the brightest colour-
schemes of an artist’s canvas look pale and bleached when held
against the brilliant illumination and intense coloration of actual
outdoor nature, and colours and markings of the oddest kinds and
most irregular shapes may be the best disguises.

As I have already said, it is necessary to be careful to distinguish
between the possible usefulness of coloration and the causes which
80 CHILDHOOD OF ANIMALS

have brought it into existence. But I think it is plain that as we
pass from the patterns that are the fairly obvious result of growth-
forces, such as the simple geometrical markings which are visibly
structural, through the more irregular stripes and blotches which
may be set down to irregular growth, to counter-shadings and
elaborate background-matching, and still more to odd and brilliant
disguises of the true contours of the body, we come into regions
where we may more and more expect that the results have been
shaped and controlled by a process of natural selection and serve
some purpose of direct utility to their possessors.
CHAPTER VI
COLOURS AND PATTERNS OF YOUNG MAMMALS

THE difference in coloration between young mammals and _ their
parents often depends simply on immaturity. The skin may be
smooth and soft, the scanty hair silky in texture, and the general
coloration pale, merely because the young animals are not yet
fully developed, because their structure is incomplete and the
physiological processes which produce pigment are feeble and in-
effective. The little creatures, in fact, may remain partly embryonic
after they are born, and differences due to this belated development
are especially plain in those species where the young are feeble and
most dependent on their parents. The first liveries acquired by
such animals, as well as the liveries of those that come into the
world active and furry, often differ in a remarkable way from the full
dress of the adults. If the adults are spotted, the young are always
spotted ; if the adults are striped, the young are either striped or
spotted ; even if the adults are self-coloured, or have acquired one
of the striking patterns of the higher grades that not only do not
conform with the architectural lines of the body but serve to
disguise or interrupt these, then the young may still be striped or
spotted.

I do not think that there is any doubt as to spots and stripes being
simple growth patterns, outcrops of actual structure, and not
devices that have been invented, so to speak, by nature for special
purposes, although as they were present they have often been turned
to account. A good many years ago, Dr. Bonavia, an ingenious
surgeon-naturalist, published a number of essays on the markings
of mammals, and compared such patterns as the dappling of horses,
the rosettes of the jaguar, the spots of leopards and of other cats,
with the armour-like scales of armadillos and their gigantic extinct
allies. Certainly many of the extinct mammals were armoured,
and if we go back still further to the reptilian ancestors of mammals,
we come to a set of creatures in which a coating of heavy, sculptured
scales was the rule and not the exception. It would be pressing the

81 F
82 CHILDHOOD OF ANIMALS

comparison too closely to insist that the markings of modern
mammals were the actual relics of lost scales, but the presence of
scales and of spots and reticulations and stripes (the latter being
lengthened spots or rows of spots that have fused) may be similar
expressions of the nature of the external covering of the body. The
skin is not a continuous sheet, uniformly stretched over the body,
but is a composite structure growing from many centres, supplied
by different nerves and blood-vessels, and may well reveal this
composite character by a tessellated appearance, retaining this
where it is useful, or harmless, as in the well-guarded young, or in
the least conspicuous parts of the body of adults, or have it obliterated
where it is harmful.

The possibility of changing the pattern and colour of the exterior
of the body comes about in mammals and birds because these for
other reasons are able to moult. Animals have to contend not
only with the larger kinds of foes which are able to pounce on them,
kill them and devour them bodily, but with a multitude of minute
enemies which harbour on the outside of their bodies and injure their
health in many ways. The spores of bacteria and moulds are rained
on them from the dust of the air, are rubbed on them by contact, or
are floated on them in water. Fleas and bugs, lice and ticks, a
prolific swarm of hungry vermin, provided with biting and sucking
organs, grasping hooks, claws with adhesive pads, and devices
innumerable for maintaining their position if once they reach the
body, assail them. These parasites may do much or little direct
harm ; sometimes they feed only on the waste secretions of the body
and do little more than cause a tickling irritation ; sometimes they
burrow deeply, or scratch and gnaw until they produce serious
wounds, or weaken their host from direct loss of blood. Still
more often those that are blood-suckers do damage, not only directly,
but by introducing the seeds of diseases that may be fatal,
carrying them from infected to healthy animals. Many of the
soft-skinned lower animals, such as newts and frogs, and still more
worms and slugs, whose bodies would otherwise be a ready prey, are
protected from the attacks of external parasites by their power of
producing slimy secretions which float off the intruders before these
have time to establish themselves. Other animals keep their skins
clean by a process acting like the scaling paints with which the sub-
merged parts of warships are covered, to prevent their bottomsgetting
fouled with barnacles. The outer horny layer of the skin is constantly
shed off, carrying with it many of the parasites and leaving the
COLOURS AND PATTERNS OF MAMMALS 83

surface clean. Sometimes this process is slow and continuous,
as in ourselves, sometimes it takes place at regular intervals, in
large sheets which may extend to the whole body, as when a serpent
sloughs, casting off the complete outer layer of the skin, even to the
transparent membrane of the eye.

The warm coats of fur or feathers which protect the bodies of
most mammals and birds are formed chiefly of the outer horny
layers of the skin, and, within certain limits, can be cast off and
renewed. This process of moulting is useful in many ways. It
gives the opportunity of replacing coats that have become worn
and faded, by coats that are bright and clean. It gives the oppor-
tunity for a change of clothing from the warm covering necessary
in winter to the lighter covering which is more healthy in warm
weather, and perhaps most important of all, it makes possible
periodical changes in colour and pattern. Just as when the outer
layers of the skin are shed off they may be replaced by differently
coloured layers, so the old hairs or feathers, when they fall off, may
be replaced by hairs and feathers with different colours and patterns.
It is the process of moulting far more than any actual change in
skin, fur or feathers that underlies the differences between young
and old animals, or between mature animals at different seasons of
the year.

Lemurs, monkeys and human beings form the most highly modified
group of mammals, the group that is furthest removed from the
reptilian ancestors, and I do not know of any in which either the young
or the adults are spotted or striped, except that the tails are some-
times ringed. The skin is usually dark, but there may be brightly
coloured patches on the face and other areas not covered with hair,
and these, whatever their use may be, fall into the higher grades of
coloration and do not conform with the structural lines of the body.
The hair also is either uniform, or decorated with crests, ridges or
tufts which, like the patches on the naked skin, seem to be late
additions to the coloration of the body, and differ much in closely
allied species. Monkeys, like human beings, moreover, have lost
the habit of moulting regularly, and are continually shedding off
and renewing their hairs. The change is modified by exposure to
cold, and the coats of thosé that have access to the open air all the
year round become longer and thicker than those of animals housed
in heated apartments. And so there are no startling differences
between the young and the adults. Like human beings, young
monkeys are born with a very scanty coat of silky hair, large parts
84 CHILDHOOD OF ANIMALS

of the body being naked. The face, hands and feet are usually
black in monkeys, but just as the hands and feet of negro infants
are paler in colour, so these regions in very young monkeys are white
or pink (see Plate IX, p. 165). A complete coat of fur appears in a few
months, and if there be no difference between the sexes, it is like
that of the adult from the first, but paler. The face and hands
acquire the pigmentation more slowly, and if there are brightly
coloured patches of naked skin, these are the last to appear and do
not acquire their full richness until the animal is almost adult. So
also the beards, crests and special tufts, often strongly marked in the
males, appear towards maturity. The three plates (I, Frontispiece ;
TX, p. 165; and X, p. 166) showing young anthropoid apes, and
human children, the mother and young of a langur monkey and of
a lemur all show the similar differences between young and adults.

The Cats, great and small, show abundant traces of a primitive
spotted pattern. The spots are most frequent in the young. In
some they are retained throughout life over the whole body in both
males and females; in others traces of them remain on the under
parts, or on the sides, especially in the females ; in others, again, they
are found in the winter fur but disappear in the summer fur. In
some they have elongated or fused to form stripes, or are twisted
into spiral markings. In others they are obliterated, being washed
over, so to speak, with an even tint, and this tint may be still
further elaborated by the appearance of special markings, coloured
manes and so forth. The whole group shows extremely well the
replacement of the primitive growth pattern by patterns of higher
grade. The changes in coloration are produced either by a gradual
loss and replacement of the individual hairs—and this usually takes
place in the natives of tropical countries—or by a regular moult at
the beginning of the warm season and a slighter moult with a rapid
growth of thick fur at the beginning of the cold season. The
winter coat is often lighter in colour because of the growth of a very
thick under-fur ; sometimes, as in the Northern lynx, it is more
spotted, but usually it is paler and less brightly marked with
shades of black and orange than is the spring breeding pelage.

The young are always born with a thick and soft coat of fur.
In the tiger and the striped cats and in all the spotted cats, the
coloration of this differs from that of the adult only in being rather
paler, whilst in those cats which are brown in the adult condition the
young are profusely spotted. Young lions are thickly set with spots,
especially on the sides and under parts, whilst the tail shows signs
COLOURS AND PATTERNS OF MAMMALS _ 8s

of dark rings (Plate ITI, p. 62). Although pumas are nearly uni-
formly coloured, tawny-brown in winter and redder brown in
spring, their cubs are vividly marked with black, stripes and spots
on the face, a broad band on each side of the face, spots on the
legs and under-parts, and rings on the tail. Caracals, until they
shed their puppy coat when they are about six months old, are very
brightly spotted on the under surface, whilst lynxes, which are
' greyish-brown in their adult summer coats, are profusely spotted
with black when they are young.

The young of these cats are so carefully hidden, and so zealously
guarded by the mother—who is more ferocious in defence of her
cubs than the females of other species—that they have little need
of the protection that concealment might give. I do not doubt but
that a spotted coat serves as a protection, partly by breaking up the
outline, and still more in the case of those animals that live in the
forest and crouch for their prey at the edges of open glades, or
lie along the branches of trees where their marks would blend with
the dappled disks of light and patches of shadow formed as the
sunlight filters through the foliage. It is more than probable
that the spotting of adult jaguars and leopards, servals and cheetahs,
and the various spots, stripes and blotches of the smaller cats are
the patterns of the young, retained and made more vivid by natural
selection. It is usual to see a relation between the vertical shadows
thrown by reeds and tall grasses and the striping of the tiger, and it
is a fair supposition that the coat of that splendid cat is a still further
modification of a primitively spotted livery. The self colour of
lions, pumas, caracals and lynxes has unquestionably come about
by the obliteration of the spots found in the young, and in adult
life traces of spots remain in varying degrees, but most strongly on
the under surface and on the legs where they are least conspicuous.
It seems certain that the spotted skin of young cats, like that of
many other animals to which we shall come later, is a natural growth
pattern which is retained in adult life where it is useful, or accentu-
ated by transformation into stripes, or obliterated to a self colour.

The small carnivores, such as civets, genets and linsangs, bintu-
rongs, ichneumons and mungooses, show a similar general set of
patterns. In almost any group, some are spotted, others are
striped, whilst in a few of the adults the coloration is nearly uniform
except for the usual counter-shading, and it is not difficult to see a
general relationship between the kind of coloration and the nature
of the ground in which the animals are habitually found. In all
86 CHILDHOOD OF ANIMALS

cases where the adults are spotted or striped, the young are spotted
or striped ; I do not know of any case where a self-coloured young
acquires spots in the adult condition. On the other hand, some
at least of those which are unspotted in the adult condition, such
as the binturong, are spotted and blotched when they are young.
As the kittens of all these animals are born in holes, and are sedu-
lously guarded by the mothers, the existence of spotted young cannot
easily be explained as a special adaptation for protection, but is a
survival from some remote ancestral condition.

In hyenas, wolves, dogs and foxes, there is seldom much differ-
ence in pattern between the young and the adults, although the fur
is shorter and usually thicker, and spots are common on the under
parts. Some of the jackals have distinctive liveries, and in these the
cubs are more simply coloured. The black-backed jackal, for
instance, has the sides reddish, the legs and the upper part of the
tail yellowish-red, whilst the back and the end of the tail are black ;
but the cubs are nearly uniformly coloured, a dusky brown above
and yellowish-brown below. The canine animals vary a good deal in
their mode of moulting, but the northern forms have a fairly definite
autumn and spring moult. Arctic foxes, for instance, which are
white in winter, shed the greater part of the summer coat in a few
weeks, replacing it gradually by the thick white winter coat ; whilst
in early summer or spring of the following year they again shed the
winter coat and replace it by the thinner, dark summer pelage. I
do not know how soon the cubs of Arctic foxes become white; I
should guess from analogy that it is not until the second winter,
as the puppy coat of most canine animals persists as the first
winter coat, and the moult takes place next spring, the puppy then
acquiring the usual characters of the adult. Nepal mastiffs in the
London Zoological Gardens moulted their under-fur early in spring.

Young bears are extremely like the adults, and the puppy coat
appears to be retained as the first winter coat. The tropical bears,
such as the Himalayan, sloth and sun bears, change the hairs singly,
and have no thick under-fur. The polar bear sheds the thick under-fur
and a considerable portion of the whole coat in the water rather
early in spring, at least in the case of bears in captivity ; in autumn
much of the coat is shed singly hair by hair, but the chief change is
the growth of a thick under-fur. The brown bears and grizzlies
moult off the thick winter fur in masses early in spring. With
bears, like most of the wolves, dogs, foxes and jackals, there is no
striking difference between the patterns of the young and the adults.
COLOURS AND PATTERNS OF MAMMALS 87

The many families of small carnivores, such as raccoons, pandas,
coatis, martens, polecats, weasels, gluttons and skunks, ratels,
badgers and otters, have generally brilliantly marked fur, with ringed
tails, striped bodies, or conspicuous marks on the head or body ;
nearly all of them have an autumn and a spring moult, and there are
many cases where the pelage of summer and winter is notably differ-
ent, in colour as well as in quality. The young are born in holes or
nests, usually in an imperfect condition, nearly always blind, and
sometimes naked, as in the polecats and mink. Even if they are
born with fur, the first coat is fine and silky, very often white in
colour, and this towards the end of the autumn is gradually replaced
by a rough puppy coat which persists until the spring moult. It is
possible that the light colour of the first coat may make the animals
more visible to the mother in the dark holes or nests where they are
born. They are born in an immature condition partly because the
mothers have to catch their prey by agility and would have difficulty
in obtaining a living when heavy with young.

The seals are probably terrestrial carnivores which have taken to
living in the water, although they come ashore to breed. The
young are born covered with hair and in a well-developed condition.
The young of the eared seals, which include the fur seals, sea-lions
and sea-bears, are able to swim in an hour or two after their birth, and
the first coat is thick but silky and in almost every case very much
darker than the pelage of the adults. The young of the true seals,
which have no external ears and in which the hind-legs are turned
backwards and dragged after the body on land, instead of being used
for progression, show a curious reluctance to take to the water, and
may spend weeks on shore. They are born with a white and silky
coat which is shed very quickly, and replaced by a longer and more
woolly puppy coat. In the grey seal familiar on the wilder parts
of the coast of Great Britain, the young are at first pure white, with
silky hair, but in a few days this coat becomes yellower and woolly,
partly by the growth of new hairs ; in about six weeks this infantile
coat is moulted off and replaced by a shorter and thicker coat of
particolour, yellow mottled with grey and black. In about seven
months there is a second moult and the third pelage resembles that
of the adult, but this may not be fully attained until after another
moult. The colours of the adult vary much, and there seems to be
no special meaning in the changes at the successive moults.

The young of all the ruminating Ungulate animals are born in an
advanced condition, andit is by far the most usual case for the pelage
88 CHILDHOOD OF ANIMALS

to differ little from that of the adult, except in the absence of specially
marked manes and beards. All those that live in cold countries
assume a thick winter coat which they shed in spring, and the pattern
of this coat may be a little different, whilst its hairs are longer,
more closely set and rather woolly. The young animal begins to
assume the appearance of the adult in the spring after its first winter,
but usually moults once, a few weeks after it is born, replacing a
sparse puppy coat of rather long and silky hair by a thicker coat.
Amongst cattle there is little difference between young and adults,
but the coat of the young is usually lighter and redder, and where the
adult has a strongly contrasting pattern of black above with white
under parts and white “stockings,” this is less conspicuous in the
young, suggesting that the adult pelage is a later acquisition. Thusan
adult wild gayal bull has an almost black back, with white stockings ;
the calf is brownish-red with only the inner sides of the legs white,
whilst the young banteng is coloured like the young gayal, except
that it has a dark stripe along the back. In sheep, goats and
chamois the patterns of the young and the adults are almost identical,
although in some of the brightly patterned wild sheep, like the
mouflon, the young show almost no trace of the diversified coloration.
The great family of antelopes show many conspicuous colour
patterns, and differences between the young and the adult are frequent.
The hartebeestes, bontebok and gnus live for the most part in open
plains, and except for counter-shading are usually self-coloured in
some yellow, brown orre dish shade, with various bands or blotches of
black and white, such as round the upper parts of the legs, on the
face or on the rump, which certainly have a ruptive effect—that is
to say, they break up the natural outline and obscure the contours,
when seen from a distance. The calves are much more uniformly
tinted, suggesting that, as in the cattle, the conspicuous patterns of
the adult are later acquisitions. The duikers, a family of antelopes
with very small horns, which haunt long grass and brushwood, have
a coloration ranging from pale mouse-colour to bright bay, whilst
many of them have broad dorsal bands or saddles of black or white or
yellow, and various face and head marks which have a secant,
outline-interrupting effect, and in these the young show the con-
spicuous pattern of the adult in a very faintly marked fashion, if
at all. There is one striking exception, however. The banded or
zebra duiker of Liberia (Fig. 23) has the tawny back marked with
bands of black arranged like the hoops of a barrel, and this pattern is
practically alike in the male, female and young. The klipspringer,
COLOURS AND PATTERNS OF MAMMALS 89

oribis, dik-diks and the reed-bucks, water-bucks and kobs are seldom
brightly patterned, and the young are very much like the adults.
In the very large family of gazelles the patterns are seldom con-
spicuous ; the general coloration is a shade of fawn, lighter below,
frequently much darkened on the back, especially in old males,
whilst face markings, rump patches and lateral stripes are frequent.
Where the young differ from the adult, they are almost invariably
more uniformly coloured. In the large sable, roan, oryx and beisa
antelopes, brilliant secant and ruptive pattern is frequent, the

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Fic. 23. Young and Adult Banded Duiker Antelope.
(After JENTINCK.)

general browns and tawny-reds being interrupted with vivid patches
and streaks of black and white. The coloration of the young is
much simpler, the general uniformity being little interrupted. The
very beautiful tragelaphine antelopes, which include the largest
members of the group, show an interesting condition. The
males and females are often very different in coloration, the males
being much darker, sometimes almost black, whilst the females are
usually reddish-brown. Stripes and spots of different kinds are
present in so many members of the group that they seem to be an
ancestral property. There are often large, rather irregularly placed
white spots on the hindquarters, and there may be lines of spots
along the flanks, or these may be joined to form continuous stripes.
Finally, there may be spots arranged in the form of hoops across the
back, but in most cases these rows are actually joined to form bands.
90 CHILDHOOD OF ANIMALS

The young almost invariably resemble the females in general tawny
coloration, and have the stripes and spots more brightly marked
than in the adults. The new-born calves of the South African
eland, which is the common species in Zoological Gardens, are
born with rather a shaggy coat the longer hairs of which are shed
very soon, and then the barrel-hoop stripes of white become visible,

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Fic. 24. Young and Adult Selous’ Sitatunga Antelope.
(Partly after SCLATER and THOMAS.)

but fade out as the animals grow up, usually remaining rather
brighter in the females and being nearly obliterated in the males.
In the Derbian eland they remain more visible in both sexes, and the
same occurs in the kudus. The young Selous’ sitatunga antelope
(Fig. 24) has a livery of reddish-brown with spots on the flanks, and
rows of spots just fusing into barrel hoops across the back ; but these
have faded out almost completely in the adult female, and com-
pletely in the adult male, which is dark brown. In Speke’s sitatunga
and the Congo sitatunga, the contrast between adult males and
females is not so great ; slight traces of the stripes are retained in the
male, rather more in the female, whilst the young is as richly marked
COLOURS AND PATTERNS OF MAMMALS or

as the young Selous’ sitatunga. The splendid bongo and angas
antelopes retain the spots and hoops of the young in both sexes,
although in the latter the adult male becomes nearly black. The
young harnessed antelope has spots on the hindquarters, stripes
along the side, and barrel hoops across the back, and a general
reddish hue very like the young sitatunga ; whilst these fade but still
remain visible in the darker adults. The male nilgai or “blue bull”
of India is bluish-black, whilst the female and the young are tawny
and there is no trace of spots and stripes in any of them,

In antelopes generally there 1s to be noticed the same general
tendency that occurs amongst the carnivores. When the young
differ in pelage from the adults, they resemble the females more
closely than the males ; they show far less trace of special ruptive
and secant patterns, of those patterns which follow the primitive
contours of the body least, and show frequent traces of spots and
stripes, and similar simple growth patterns.

The prongbuck or American antelope, which lives in upland
prairies and on rocky slopes where the snow lies in patches until
late in spring, and descends again in early autumn, is one of the
most striking examples of ruptive pattern. The back is rich tan
with black on the head, and great disks of white on the rump, whilst
the face and sides have patches and areas of white sharply marked
off from the darker regions. The females have similar but less
brightly marked patterns, whilst the young are almost uniformly
clad in pale greyish-brown with only the faintest trace of the adult
coloration. Here is another instance of one of the highly specialised
patterns which cannot be easily associated with the natural structure
of the body, appearing only with adult life.

The well-known pattern of the Giraffes (see Plate II, p. 11) suggests
in a vivid way the origin of colour pattern from the tessellated or
particulate character of the skin. It consists of a series of spots or
blotches which grow darker with age, placed on a pale background,
and in some species leaving only a narrow reticulation of the pale
ground between the spots. The young, as soon as they are born,
show the spots clearly marked. Many hunters have borne witness
to the fashion in which this apparently vivid pattern makes the
animal almost invisible as it stands under the trees on which it
feeds, and it appears as if the pattern were a simple growth form
that had been retained because it was either positively useful or at
least harmless.

Deer show a most interesting set of differences in the relations
Q2 CHILDHOOD OF ANIMALS

between the young and adult patterns. The young, in by far the
greater number of species, are spotted, and although it must cer-
tainly be the case that this pattern helps to conceal a fawn lying
quietly in the shadow of trees, the presence of spots is so common,
whether the deer inhabit woodland or not, that it seems more
natural to think of it as a primitive growth character such as is
found in many other groups. In some deer the spots are retained
throughout life. The beautiful axis deer is always brilliantly
spotted, and as it haunts the neighbourhood of trees and comes out
readily in the daylight, it may well be that its dappled hide is a
protection. The Formosan deer is brightly spotted in its summer
coat, and the spots persist, although they are less plainly marked,
in the lighter winter coat. The fallow deer are also haunters of
woods and forests; in the most familiar form they are brightly
spotted, like the fawns, but the spots disappear with age, and
local varieties are Known without spots, whilst it has been recorded
that some of the fawns are unspotted. In the Japanese deer the
fawns are spotted, but the adults in winter are uniformly clad in
dark brown, and change again in summer to a lighter spotted coat.
The fawns of the hog-deer and the Barasingha or swamp-deer are
spotted, and there are rows of spots in the brighter summer pelage of
the adults, which are lost in winter, toberenewed again. Ina very
large number of deer belonging to different groups and with very
different haunts and habits, the spotted coat of the fawn is shed ina
few months, and although there may be regular changes from summer
to winter and from winter to summer pelage the spots never again
reappear. This happens with the common red deer (see Plate V) and
wapiti and their allies all round Europe, Asia and North America,
with Eld’s deer, roe-deer, the Chinese water-deer, the curious little
brocket deer of America, the Virginian deer, the mule-deer and
the very peculiar musk-deer. Finally, there are a few deer belonging
to different groups in which there is no trace of spots in the young
or the adult. Amongst these are the Sambur deer, except the
Philippine Islands form, the muntjacs, reindeer, elk and the Ameri-
can guemals and pampas deer. It is at least interesting to notice
that spots tend to disappear in winter coats and in the northern
races of deer, and that they are retained in deer which are not
nocturnal.

The pig-like little chevrotains or mouse-deer come very close to the
ruminants, but do not actually ruminate, and in many ways are
intermediate between deer and pigs, certainly representing a very
PLATE V

GROUP OF RED-DEER: STAG, TWO
HINDS AND A SPOTTED FAWN
 
COLOURS AND PATTERNS OF MAMMALS _ 93

primitive type of animal that has survived. In the Indian
chevrotain and the African water chevrotain, the bodies of the
young and adults are alike, reddish-brown, and much spotted with
white, the spots being often joined to form bands. In the adults
of two other species found in the Malay archipelago the coloration
is more uniform, darker above and lighter below; the smaller one
shows traces of faint lines recalling those of other chevrotains, and
these are more strongly marked in the younger animals. I have
been unable to find any account of the pattern of the very young
individuals, but it is highly probable that it is spotted or striped.

In the Bactrian camel, the dromedary, and in their American
allies, the wild vicugna and huanaco, and the domesticated llama
and alpaca, the young are rather paler and more uniformly coloured
than the adults, but resemble them very closely.

If we turn now to the non-ruminant, cloven-footed Ungulates, we
find some more cases of differences between the young and the adults
which are not readily explained as direct adaptations for protection.
In all the true wild swine the young are paler and pinker than
the adults, in which there is almost always much dark brown and
black. The little pigs are pale or reddish-brown, and are marked with
longitudinal rows of stripes, rather faint and irregular, and partly
broken into spots. So also the young of the pigmy hog, the river-hogs
and the wart-hogs are striped. Certainly these animals haunt ground
where a striped pattern might aid in making them less visible, but
the stripes are faint, and not sufficiently clearly marked on the ground
colour to have much effect, whilst the parents guard their young
with so great devotion and with so powerful weapons that the little
pigs have no need of concealment. It is much more probable that
this is another example of natural growth pattern. The curious
babirussa of Celebes is uniformly coloured in the young and in the
adult, and the American peccaries have the same pattern when
young and adult.

The hippopotamus is self-coloured, and its young differ from it
only in being much paler and pinker.

Among the Odd-toed Ungulates, the tapirs, rhinoceroses and
horses, it is only the tapirs that present a striking case of difference in
pattern between young and adults. The full-grown American tapirs
(see Plate VI, p. 94) are nearly uniformly coloured, dark grey-brown
or black above, a little lighter below, but with a white line round
the edge of the shell of the ear. The Malay tapir has the head,

orequarters and legs very dark brown to black, but the whole of the
94 CHILDHOOD OF ANIMALS

hinder part of the body above and below is white and there is the
same rim of whiteround theears. There is no difference in the colora-
tion of the sexes. The dull coloration of the American animal,
with its counter-shading, may well suit the muddy edges of the
rivers and lakes and marshes it inhabits, whilst the black and white
of the Malay species is a good example of ruptive pattern, and when
the animal is lying amongst the boulders at the edge of a river in the
tropical sunlight, is said to be extremely difficult to see. But the
young tapirs, both in America and Asia, follow their parents closely,
and share their surroundings, and yet are amongst the most vividly
patterned of living animals. Their dark bodies are profusely
striped and spotted with white, the stripes and the rows of spots
being arranged longitudinally like those of young pigs, and being
extremely alike in all the species. I think that it cannot be doubted
but that this infantile pattern (which is lost in a few months) is a‘
natural growth pattern. Its similarity in American and Malay
forms, which are so unlike as adults, points to such an explanation
being correct.

In the several species of rhinoceros the coloration is nearly
uniform, and the young differ very little from the adults, except that
they are more hairy and paler. The thick hide reveals its com-
posite or tessellated structure, not by differences of colour, but by
differences of texture, being broken up in the Indian animals into
great masses, like armour-plates, separated by more flexible grooves.
The continuous barrel-shaped area from behind the shoulders to
the hind-legs, together with the plate covering the rump, correspond
rather closely with the region that is white in the Malay tapir. In
the young African rhinoceros there are hoop-like ridges over the
back and flanks, at first sight suggesting that the ribs are showing
through the skin, and which, if they happened to be expressed in
differences in colour, would transform the animal into a vividly
patterned creature. In the African and the Indian species alike
the hide is marked with a series of bosses and hexagonal areas which
again only lack differences of colour to become a conspicuous
pattern.

Except that foals are rather more lightly coloured than adults
and frequently have a continuous mane of short erect hair
Tunning along the middle line of the back, young horses, asses and
zebras differ very little from their parents in coloration and pattern.
Spots, dapplings and stripes are extremely common; if they are
present in the adults, they are always present in the foals, and not
PLATE VI _
AMERICAN TAPIR AND YOUNG
 
COLOURS AND PATTERNS OF MAMMALS — 95

infrequently traces of them occur in foals and fade out when the
colouring of the adult has been reached. It is difficult to resist
the conclusion that a striped pattern is primitive in the group and
represents a natural growth pattern which is in course of oblitera-
tion. Grevy’s zebra is the most completely striped of all the
animals in the group, and the other zebras show a gradual transition
to the unstriped donkeys, some of the stripes fading out and ap-
pearing only as shadow stripes, the stripes on the legs and under side of
the body disappearing next, until the quagga pattern is reached, an
animal which was not much more marked than many donkeys. When
zebras are crossed with horses, the stripes are more numerous even
than in the Grevy zebra, but are extremely faint. When they
are crossed with donkeys, the stripes are more numerous than in
donkeys and very brilliant, but less numerous than in zebras.

The conies or hyraxes resemble their parents in coloration very
closely, but are generally rather darker, and the young of different
species are more alike than the adults.

Young elephants are lighter in colour and much more hairy
than the adults.

Nearly all the Rodents are quietly coloured creatures with little
or no difference in pattern between the males and females. They
are the prey of many enemies and have little powers of defence.
They are disposed to avoid daylight, coming out just before dusk
and again in the very early morning about dawn. Their subdued
hues suit their habits. They are usually self-coloured with more
or less of counter-shading. A few are striped or spotted, the stripes
or rows of spots always being arranged along the length of the animal.
Some of them, however, and particularly the squirrels, are vividly
coloured, the colours being in great masses or patches. There are
usually two moults in the year, the winter pelage being duller and
less brightly patterned, whilst the vivid colours are assumed for the
breeding season. The young are often born in underground nests,
in hollow trees, or in other dark and well-concealed places, and
those that are produced in such nurseries are very immature, naked
and blind. On the other hand, if, as in the hare, the young are
born in the open fields, and have to run the danger of being dis-
covered by enemies, they come into the world in a more mature con-
dition, able to see, and clad with fur. When the first coat of fur
has been gained, it is striped like that of the adult, in the striped
forms ; in others it is a paler imitation of the adult pattern.

The Marsupials are still more quietly coloured than rodents, a
96 CHILDHOOD OF ANIMALS

certain amount of counter-shading being the chief variation in the
general clothing of dark grey or brownish fur, but a few like the
spotted dasyures and the striped Tasmanian wolf have special
patterns. The sexes are always alike, and the young, which are
born as naked and quite immature embryos, acquire the pattern of
the parents as soon as they become clothed with fur.

If we consider the patterns of mammals as a whole, it is plain that
the simplest and most primitive types consisted of spots, and
that these were the expression of the tessellated or particulate
character of the skin. In the natural course of growth these spots
may expand into short stripes, or they may fuse to form bands
running hoopwise across the body, or along its length. If there is
a pattern of this kind in the adult, it is always present in the young.
Undoubtedly it must often aid in making the young animals or
the adults invisible as they lie in the dappled shadow of leaves,
but the pattern occurs so often, in so many different kinds of animals,
living under so different conditions, that although it may have been
retained because it was useful, it does not seem probable that its
usefulness is the direct cause of its origin. Very often the primitive
spots or stripes are replaced in the adult by an even tone, marked
only by counter-shading, and sometimes this monotonous tint
appears even in the first coats of the young. The fact that it so
often replaces a primitive livery of spots would seem to show
that it is of later origin, a more highly developed kind of pattern.
Lastly, it very frequently happens that instead of a monotonous
shade, the body is marked by vivid patches of light and shade, or
of colour, over regions that do not seem to correspond with structural
differences of the body. These showy, conspicuous patterns are
often ruptive, and may serve for concealment by breaking up the
natural outlines of the animals. When they are present, they are
generally more strongly marked in the males than in the females,
and they replace either the monotonous or spotted or striped
pattern of the young.

The changes from juvenile to adult patterns are frequently
abrupt and are associated with the natural autumn or spring
moult. When the young animals become nearly full grown in one
season, they appear first in the rough and plainer winter pelage ;
when their youth lasts longer, it is not until the moult after the first
winter that they assume the pattern of the adult.
CHAPTER VII
COLOURS AND PATTERNS OF YOUNG BIRDS

THE complicated changes in the outer coverings of mammals enable
us to understand the still more complicated changes in birds.
Primitive mammals appear to have been spotted or striped, marked
with patterns that were the expression of the nature of their skin,
and of the natural processes of growth. These simple patterns were
replaced by patterns of a higher grade, first by a process merely of
obliterating them, then by changing them still further by the
development of counter-shading, of secant and ruptive marks that
disguised the natural shape, and of various exuberances of ornamenta-
tion. Inavery large number of cases the primitive growth patterns
are repeated in the young ; sometimes these have disappeared even
from the young, which start life in a garb of the second grade, and
acquire as they become adult, and especially if they are males, the
highest and most specialised kinds of coloration.

Feathers are even more important to birds than fur is to mammals.
Their arrangement, colour and patterns make up the greater part of
the appearance that a bird presents to the world, to its friends or to
its enemies ; the body of a plucked bird has lost the characteristic
size, shape and appearance to an extent that is almost grotesque.
The down and contour feathers retain the internal heat of the living
body, a necessary protection as the blood of birds is hotter
than that of mammals and as their physiological processes are more
active. The quills of the wings and tail form the light and strong
expanses which are used in flight. A feather is a more elaborate
organ than a hair, and there are many kinds of feathers, several
kinds of plumage and a very elaborate system of moulting.

The most characteristic feathers are the large quills which lie in a
single row along the outer edge of the joints of each wing and are
disposed fanwise on the tail. These are found in all birds; their
quite obvious presence in the flightless ostrich shows that that bird
and its allies have lost a power of flight which they once possessed, and
they can be identified even in penguins. Brush turkeys are the

C.A. 97 G
98 CHILDHOOD OF ANIMALS

only birds in which they are so fully formed at the time of hatching
that they can be used for flight at once, but they appear very quickly
in all young birds and can often be counted long before the chicks
have left the egg. Quiulls are usually replaced once a year. Some
water-fowl shed them all at once, and in their unhappy flightless
period have to hide in the reeds in some sheltered corner of a lake,
an easy prey to any foe that discovers them in their day of peril. In
most birds they are shed and replaced in pairs, so that at any time
there are not more than one pair in the wings and one pair in the tail
out of action, and there are always enough for flight to.take place.

Besides the quills, there are two kinds of feathers, more or less
corresponding with the fur and the under-fur of mammals, There
are the contour feathers which make up the greater part of the
covering of the body, giving that not only its shape but most of its
colour and pattern, and forming the decorative plumes on head
and wings and tail. They are not spread evenly over the surface
of the body, but are inserted on special regions, with naked spaces
between them in all except a very few birds, and even in some
of these, such as the ostrich, they are arranged on definite tracts
in the young bird, although they are evenly distributed in the adult.
Secondly, there are the softer, more tuft-like down feathers, corre-
sponding with the under-fur of mammals, and like that found most
abundantly in creatures which require special protection from cold.
These may be attached to the interspaces between the contour
feathers, or they may be distributed all over the bird, or they may be
found only on the feather-tracts, concealed by the other feathers.
It seems most probable that these down feathers are a later develop-
ment and are degenerate contour feathers, the only purpose of which
is to thicken the warm covering of the body.

There are many reasons why birds should moult, and from time to
time renew their outer garment, which is at once an ornament, a
protection and a most useful organ. Feathers are fragile and quickly
become frayed, broken or worn. In a few cases the wearing of the
tips of the feathers at first smartens the plumage. The throat of the
sparrow is dingy in winter, mottled with brown and black, but as the
tips of the feathers wear off they reveal the brilliant black band
which decorates the bird in spring. So also the rosy pink of the
linnet’s breast in spring appears only when the dull tips of the winter
feathers have been worn off. In some birds, this accident has been
transformed to a system. Many brightly coloured ducks acquire
their brilliant breeding plumage in autumn, and yet in spring, when
COLOURS AND PATTERNS OF BIRDS 99

courtship begins, become still more brilliant, not by a new moult, but
by discarding the pale tips of their bright feathers. Such devices
are on the whole rare and at the best are expedients which make
the feathers last a little longer. Sooner or later, if the plumage is
to retain its usefulness or to alter its appearance, it must be
changed by a moult.

The moults are sometimes associated with changes of colour and
pattern, and sometimes merely lead to the restoration of the dis-
carded dress in a fresh condition. When there is no brilliant
breeding plumage, and especially when both males and females are
sad-coloured and much alike, the moults may be numerous in a
single year and yet the coloration remain uniform. Such dismal
creatures are exceptions. Most birds are brilliant for a part of the
year, sometimes only for a few weeks of courtship, sometimes for the
greater part of the year, and sometimes for the whole year round.
The different plumages that birds may assume successively as the
results of moults are so varied that it is not easy to get a clear
picture of them. I must begin by enumerating them and by giving
some examples of them.

First of all, the chicks may be clad in a coacing of down. This may
be replaced by one or more successive immature plumages and these
may be followed by different kinds of adult plumages. The adult
plumage may be the same all the year round, and in that case the
males and females may be alike or different. There may be a
specially brilliant plumage assumed in the breeding season, by the
males only, or by both males and females. When the breeding
season is over, the brilliant plumage may be lost, the birds passing
into what is now known as “eclipse ’’ plumage, and this may be
identical or different in the males and females. The eclipse plumage
is very often seen in winter, as spring and early summer are the
breeding seasons, and for that reason it is sometimes spoken of as
the ‘‘ winter’’ plumage. ‘“‘ Winter ’’ plumage, however, is a mis-
leading term, because it extremely often happens that it is passed
through long before winter begins. Some examples will make the
matter clearer. Jn winter, the common lapwing or peewit is a dull-
coloured bird, with a very short crest, a brownish head, a white or
grey neck, and with the back mottled with dark brown. The males
and females differ very little. In early spring a moult takes place.
The male becomes resplendent, with a long crest, and a body shining
with metallic olive-greens and purples, steely-blue and ruddy-brown,
picked out with vivid black and white. The female is a less
Too CHILDHOOD OF ANIMALS

brilliant copy of the male, with a shorter crest and a dimmer lustre.
When the breeding season is over, there is a second moult and both
sexes appear in the winter garment of repentance. In this case the
“eclipse ’’ plumage coincides with winter, and the breeding plumage
with summer. The next example I shall take is that of a very
different kind of bird. The beautiful little passerine bird known
as the superb tanager, and often seen in zoological gardens, is a
jewel of colour, shining with green, orange and shades of purple and
blue, the female being only less brilliant than the male. These re-
splendent garbs are the breeding plumage and are retained for
rather more than half the year. There is then a moult, and both
males and females pass into a dull brown eclipse plumage in which
it is very difficult to distinguish them. The contrast is not always so
great as in the two cases I have taken, and it is more common for the
female to remain comparatively dull even after moulting into the
breeding plumage. Nor is the division of the year between the two
plumages usually so regular. A dull eclipse livery for both sexes for
the greater part of the year, with a bright breeding dress at least for
the male for a smaller part of the year, is the most common state of
affairs.

No set of birds display more brilliant patterns and fantastic decora-
tions than are to be found amongst ducks, where, however, the drakes
are bright whilst the females show little colour change. This
gay plumage is found in the breeding season in its most brilliant
form, but, unlike the lapwings, drakes may retain it for the greater
part of the year. When the cares of married life are over, they
change into a dull eclipse livery, but instead of retaining that until
next spring, they put it off again after a few weeks or months, and by
a new moult again put on the brilliant colours, although the whole
winter has to be spent before spring recalls them to love. In some
ducks, especially those of South America, the eclipse plumage either
does not occur, or lasts so short a time that it has not been noticed,
or is merely a paler copy of the usual garb. In many of the game birds
there is the same double moult, but the eclipse plumage is shown
only by a few dull feathers, visible to the expert, but making little
difference in the general appearance of the bird. Amongst these,
also, the males have the resplendent colours. Lastly, there are a
number of birds, such as parrots and kingfishers, in which there is no
change throughout the year, but the most brilliant colours are re-
tained permanently, and when the single annual moult occurs an
identical livery is assumed. In these birds the males and females
COLOURS AND PATTERNS OF BIRDS _ ror

are both brilliantly coloured, usually alike, although there is the
odd case of the Eclectus parrots, that I have already mentioned,
where one sex is green, the other scarlet.
When birds are hatched, some, like ducklings and chickens, are born
with a warm coating of down feathers, and are able to run about,
see and peck almost as soon as their coats are dry. Others, such
as the chicks of most of the familiar singing birds, come into
the world helpless, blind and naked, entirely dependent on the
care of their parents. We have seen that among mammals the con-
dition of the young at birth depends on the habits rather than on the
families to which the animals belong. The older naturalists, misled
by seeing the condition of the young nestlings alike in many large
groups, thought that it depended more on relationship than on habits,
but there are so many differences, among nearly allied birds, that it
seems to be a simple adaptation to the conditions. If the eggs are laid
in safe, inaccessible places, as in nests on trees, or in holes, the young
are usually helpless. If they are laid where the young chicks may
have to take refuge in the water, or to hide in the herbage at any
moment, they are hatched only when the chicks are able to swim or to
run about. When the young are born in a precocious condition, the
eggs are larger in proportion to the size of the parents and take longer
to incubate. The average time of incubation is from eighteen to
twenty-six days; humming-birds, which lay small eggs even in
proportion to their small size, brood over them for less than a fort-
night, and the newly hatched young are naked and _ helpless.
Ostriches and their allies lay eggs which are very large even in
proportion to the large size of the parents, and when the chicks come
out they are able to run about almost at once. At the ostrich
farm of Mr. Carl Hagenbeck, in Hamburg, I have seen the actual
hatching of young ostriches from eggs that had been brooded in an
incubator. At the right time, when the chick had begun to break
its way through the hard shell, the operator helped the process, the
little bird came out, and in a few minutes was able to stand up and
take its first meal of pounded shell, whilst in less than an hour it was
running about on the warm sand of the floor of the nursery prepared
for it, and taking its food without any assistance. So also young
emus, rheas and cassowaries, tinamous, all the game birds, rails,
cranes and bustards are clothed and active when they are hatched,
and are able to follow their parents on the ground almost at once.
The sand-grouse, which have the habits of game birds, although
related to the pigeons, are born in an active condition. Shore and
102 CHILDHOOD OF ANIMALS

marsh birds, such as plovers, curlews, avocets and gulls, all of which
lay their eggs on or near the ground, have active young. Rails,
divers and grebes, screamers and all the swans, ducks and geese hatch
out as lively, downy creatures, able to walk and run, and some of
them able to swim from the first. On the other hand, penguins,
which lay a single egg and incubate it on the feet, hatch out a
blind and naked chick. Gannets and cormorants and petrels, which
lay in holes in the rocks or in trees, all the hawks, eagles and owls,
kingfishers, swifts and woodpeckers, pigeons, parrots and cuckoos,
and all the perching and singing birds, hatch out their young in
protected places and in a helpless, frequently naked condition.

Whether newly hatched birds already possess a covering of feathers
or have to wait days or weeks to acquire it, the first plumage is
usually very different from that of the adult, and a number of
successive suits may have to be put on before the full dress of the
adult is reached. The differences are partly in colour and partly in
texture.

Although the first plumage of nestlings is nearly always soft and
downy ,it seldom corresponds with the down feathers of the adult, but
usually with the contour feathers. One of the naturalists on the staff
of the British Museum, Mr. W.P. Pycraft, has worked out the nature
of the feathers in a great many young birds. He has shown that
although a newly hatched owl and hawk are both clad in a soft
white downy plumage, the individual feathers composing the covering
are different in the two cases. In the owl each down feather occupies
the place of a future contour feather, but neither in the embryo nor
in the adult are true down feathers ever developed. Each of these
first feathers of the owl is shaped like the umbel of a flower, or like
the ribs of an umbrella that has been blown inside out, and which has
had the stick cut away ; there is no central axis or stem, but the circle
of little barbs all arise from the same point. In a very short time
this first plumage is moulted off, and replaced by a second set of
downy feathers. These still occupy the place of the contour
feathers, but they are differently shaped ; each is like a true feather
and has a central stem or axis to which the feathery barbs are
attached. In late autumn of the first year the second down plumage
is moulted, and the contour feathers of the adult take their place.
In the brush turkeys, or mound builders, where the eggs are very
large, and where the young are hatched in an advanced condition, the
first set of down feathers, corresponding with that of the owls, is
formed and shed before the chick is hatched, and the second down
COLOURS AND PATTERNS OF BIRDS 103

plumage is well formed at the time of hatching. In most birds
this first plumage has been suppressed entirely. In some of the
ducks, traces of the first plumage are found ; in most of them, as in
all the game birds, only the second plumage appears. In the
nestling pigeon, even the second plumage is degenerate and appears
only as a few scattered thread-like hairs, whilst this nakedness is
carried still further in nearly all the singing and perching birds. In
kingfishers, hornbills, swifts and humming-birds, there is no down
either in the nestling or in the adult, and the final contour feathers
appear early, so that the nestlings look like small spiny hedgehogs.
In hawks, eagles and vultures, on the other hand, although there is
a thick coating of down, it is composed almost entirely of feathers
which are afterwards replaced by the true down feathers of the adult ;
whilst in cormorants, the nestling downy plumage is altogether a fore-
runner of the adult downy feathers.

It is not easy to form a general picture of the differences in colora-
tion between young birds and adults. The number of species of
birds is enormous, and although naturalists have devoted them-
selves to collecting examples in the field and forest, and to studying
them in museums, with the greatest patience and enthusiasm, there
remain many gaps in our knowledge, especially as to the changes
that individuals pass through in the course of their lives. Nature
seems to have lavished colour and pattern on the group, and to be
displaying her eccentricities, her exuberance and her whimsicalities,
rather than pursuing her usual orderly course. None the less it is
just possible to get an idea of a general course of events, an idea,
however, which must not be taken too rigidly, for there are probably
exceptions which cannot readily be brought into harmony with it.

The colours of young birds are never brighter than those of their
parents. There is one apparent exception to this, but it applies to
the skin and not to the feathers. The naked and helpless nestlings
which are reared in trees, in holes, and other rather dark and well-
concealed places, are provided with heads that seem much too large
for their bodies, and with mouths that seem too large for the heads.
The mouths are actually enormous, and when the parent birds come
carrying their spoil of worms or grubs, the huge opening seems even
larger than it is, because it is marked at the sides with bright patches
of colour, sometimes yellow as in the starling, sometimes white. The
inside of the mouth is also brightly coloured, yellow perhaps being
the most common tint, as in larks and thrushes, but red and yellow
in some of the titmice. These colours fade away as the young birds
04 CHILDHOOD OF ANIMALS

grow, and it is probable that they serve as guides to the mother. A
light may be unnecessary to find the way to one’s own mouth, but a
little help to the mouths of others may not be amiss.

The colour and pattern of the first coat of downy feathers, whether
that appears before hatching or is acquired in a few days, never bear
any intelligible relation to the coloration of the adult plumage.
Very often indeed the colour is uniform, varying from pure white
through dusky yellows and greens to pure black, and he would be an
ingenious person who could trace any connection between the shades
of the downy coat and the habits and surroundings of the young.
The ostrich and the apteryx, the largest and the smallest of the
flightless birds, are uniformly coloured, the latter being of a dusky
grey, the former grey with faint traces of the striping and mottling
seen in the other ostrich-like birds, and appearing as if the marks had
been washed out. Young penguins all wear a thick coat of down
(see Plate VII), which, although it may be a little lighter in front
and a little darker on the back, is evenly coloured ; in some, like the
common rock-hoppers most frequently seen in zoological gardens;
being very dark brown, almost black, in others being dark buff, light
yellow or dirty white with sometimes, as in the emperor penguins,
black on the head. Until man came to disturb them, penguins had
few enemies except the weather in the great rookeries in which they
breed and had no need of special protection from concealing colora-
tion. The downy coat of the albatross issooty-brown. Pelicans are
hatched naked, but in a few days their flesh-coloured skin is covered
with a fluffy coat, pure white in colour. Flamingoes show no trace of
the brilliant scarlet that decorates their adult plumage, but are snowy-
white when they are in down. Screamers (Chauna) when they are
hatched appear in a uniform coat of grey-brown, a little yellower on
the head, and set off by the brilliant red of the skin round the eyes
and the naked legs. Newly hatched swans are pure white in some
species, as, for example, in the case of the very beautiful black-necked
swan (see Plate XI, p. 240), but more usually they are yellowish.
Some of the geese and ducks, particularly the domesticated species,
are clad in a monotonous uniform of white, which may be pure white,
yellowish or dusky, but this is not the familiar uniform of their tribe.
The young of the rails, coots and moorhens are almost quite black
when they are clad in their first downy covering. Sometimes there
is a faint metallic sheen recalling the vivid colours of the adults. The
chick of the Australian waterhen has its dusky head just lightened
with a greenish-purple iridescence ; the black of the chick of the
PLATE VII
KING PENGUINS AND YOUNG

The figures to the left show the young in downy plumage,
those to the right show the adult plumage..
Sygiene ree ee

 
COLOURS AND PATTERNS OF BIRDS 105

common moorhen has a greenish lustre. The down of young owls
is usually pure white. In most of the birds-of-prey the down is
uniform ; in ospreys it is clay-coloured ; in the condor the head is
naked, but the body is covered after a few days with a thin coat
of white down. In vultures it is usually white, but may be yel-
lowish or picked out with black on the wings as in the American
black vulture, whilst in most of the eagles it is dirty yellow. In
birds which never acquire a real coat of down, but which are naked
except for a few hair-like tufts, these remnants are white or pale.

The down covering of many young birds shows a conspicuous
pattern of either spots or stripes, spots elongating to form stripes, or
stripes breaking up to form spots. These patterns resemble in a
most striking way the simple growth patterns to which I called
attention in the case of young mammals. The arrangement is
usually one that recalls the simple kind of bilateral patterns made by
squeezing ink marks in folded paper (see Fig. 21, p. 65), and although
the result mav sometimes be of use in helping to make the young
birds less conspicuous against the background, when they are squat-
ting in the sunlight amidst reeds and other vegetation, or on a
pebbly beach, they occur so constantly in many different groups of
different habits that I find it difficult to think of them as special
adaptations. They appear to be the more or less inevitable result
of the particulate character of the skin and of the mode of growth.
They have been retained in cases where they are either useful or
harmless, but they are survivals of an ancestral or primitive con-
dition which have been preserved, rather than new creations for the
special benefit of their possessors. Moreover, in many of the self-
coloured chicks there are faint indications of obliterated stripes
which would seem to show that the plain-coloured chicks have more
modern coverings than the striped and spotted forms.

The nestling rhea or South American ostrich (Fig. 25, p. 107, right-
hand figure) is covered with a thick coat of long down feathers, dirty
grey on the head and under surface, but with a long dark brown patch
on the neck which forks over the wings, and is continued along the
middle line of the back as a diamond-shaped mark tapering off towards
the region of the tail. On each side of this a broad brown stripe runs
backwards from the wings towards the tail, whilst a second stripe at
each side runs along the outer surface of the thigh and leg. These
brown stripes leave the pale grey background between them as
narrow bands. In the young emu, the same general arrangement
of dark stripes on a light background is present, but the stripes are
106 CHILDHOOD OF ANIMALS

partly broken up into rows of large spots. In the cassowary, the
dark stripes are wider than the interspaces, so that the nestling looks
like a dark bird banded with white. Grebes nest in the same marshy
streams as many of the rails and moorhens, but the down of the
nestlings is vividly striped, with dark bands running along the body.
The nestlings are carried by the mother on her back, but so also are
the self-coloured nestlings of swans.

A special but very simple pattern is found in many of the geese,
like, for instance, the cereopsis goose, the sheldrakes (Fig. 25, middle
figure) and the whole tribe of ducks except the domesticated breeds.
The ground colour is a dirty white and this is retained on the under
surface. The upper surface of the head is dark brown approaching
black, and this is carried towards the tail as a broad stripe which
expands to a diamond shape over the shoulders, with extensions
running along the wings, and broadens out again towards the tail.
Another dark band, which generally meets the median band, runs
downwards and backwards along the outer surface of the thigh. In
the sheldrakes this pattern is very plain and leaves elongated spots
of the white ground colour just behind the wings and the insertion
of the legs. In the different ducks, the dark patches and stripes
occupy more and more of the back until they may leave the ground
colour showing only as a pair of bright spots opposite the insertion
of the legs, and a less conspicuous pair of spots opposite the wings
(Fig. 25, left-hand figure). Clearly, the geese and ducks show the
gradual disappearance of the ancestral striped pattern and its
replacement by a nearly self-coloured dark back.

The downy coats of newly hatched jungle-fowl, pheasants, quail
and partridges and the other fowl-like game birds show a simple
growth pattern rather like that of the ducks and geese, and, like
it, tending to be smoothed over and replaced by a nearly uniform
tone. The ground colour varies from white to a dirty yellow and
remains unaltered over the lower surface (see Plate IV, p. 69). On the
head and back there is a dark stripe, expanding to a diamond shape
between the shoulders, and running backwards towards the tail
where it may expand again. On the hinder part of the body there
is a dark stripe running backwards at each side, separated from the
middle stripe by an unaltered portion of the light ground colour.
A similar dark band runs across each wing and down the thigh. Such
a pattern appears and reappears all through the group, however the
adults may differ, but it fades out, becoming fainter in the small
quails and partridges.
COLOURS AND PATTERNS OF BIRDS 107

Stripes, visible on the head, but fading off into the brownish hue
of the back, are found in the tinamous. Stripes or spots arranged
irregularly or just suggesting striping appear in the nestlings of wading
birds, and in most of the gulls (see Plate VIII, p. 162) and terns.

Sooner or later young birds moult off their down if they have
possessed it, and acquire a covering of true feathers. The feathers

 

   
  

   

Fic. 25. Down-plumage Patterns. To the left a
Summer-duck, in the middle a Sheldrake, and to
the right a Rhea.

appear gradually, either on the naked body or amongst the down, and
the time taken after hatching to acquire the first plumage may
differ much in very closely allied birds. The emperor penguin
remains no more than four months in the down, although the rather
smaller king penguin does not assume its first true feathers for nearly
ten months. The first feathers to appear are usually those on the
wings and tail, especially in birds that live or nest on the ground or
near the water. Young brush turkeys are able to fly almost as soon
as they leave the egg. Fowls, pheasants, partridges, ducks and geese
108 CHILDHOOD OF ANIMALS

begin to have their wings well fledged in from a few days to a few
weeks. In birds that nest in trees or holes, or high above the
ground, the flight feathers usually lag behind the others. The time,
however, is closely fitted to the habits of each species and has no
general relation to the kind of bird or to the size of the bird. A
young Californian condor, one of the largest of living birds and
which weighed nearly a pound when it was newly hatched, was at
first clad inascanty white down, but had the head naked. A month
later it was as large as a hen, and covered with a greyish down, and it
was not until it was over two and a half months old that the first
trace of true feathers appeared on its tail. When it was three anda
half months old, and weighed fifteen pounds, it was still more than
half covered with down. Some of the small singing birds, which are
naked when they are hatched, may be fully fledged in two or three
weeks.

The acquisition of a coating of true feathers, however, by no,
means implies that the young bird has acquired the pattern and
colour of the adult. A number of successive moults, occupying one
or more years, may have to be gone through before the young bird
assumes its final garb. The facts are bewildering in their com-
plexity and some of them are extremely difficult to place in an
orderly picture. The general rule, to which the exceptions are ex-
tremely rare, is that the early plumages of young birds are duller
in colour than the dullest of the adult garbs of their kind; that they
resemble the young plumages of allied birds more closely than the
various adult plumages of such birds resemble each other ; that in
colour they are extremely often brown, whatever be the colour of the
adult plumages ; and that in pattern they show such simple growth
patterns as stripes, spots, bars and mottlings much more frequently
than the adults.

The most familiar case of differences between young and adult,
plumages is that when the sexes differ, the young are like the plainer
of the two adults. Every one knows examples of this. In pheasants
(see Plate IV, p. 69) and fowls the cocks are amongst the most resplen-
dent of living creatures. Their heads are decorated with wattles,
combs, coloured patches and crests. Their plumage shines with all the
colours of the rainbow, with green and gold, purple and crimson, and
red and yellow, arranged in the most fantastic of patterns. The
cocks of different species are extremely unlike. The hens are
clothed in subdued patterns, simple stripes and mottlings, coloured
in various shades of brown, with at the most pale reflections of the:
COLOURS AND PATTERNS OF BIRDS _ 109

'glories of their mates. The hens of different species are much more
alike, so alike that it requires attention and expert knowledge to
distinguish them, whilst the poorest observer could be in no doubt
as to the specific distinction of the cocks. The chicks in their first
plumage are always very much more like the females and like the
corresponding stages in other pheasants, and here again it requires
an expert to distinguish them. An even more startling case of
brilliant males and dull females is that of the birds-of-paradise. The
fantastic extravagances of their plumes, the jewelled splendour of
their eyes and the riot of colour in their plumage far surpass the
most glowing imagination of the artists who combine all the shining
products of the loom and the most curious dyes of the chemist to
compose the stately robes of emperors. But all this exuberance is
lavished on the males. The females have to be content with dingy
garbs of mottled brown. The young birds are so like the females,
and so like one another, that it is often difficult to determine the sex
and the species until the adult state has been reached. Ducks and
drakes are another familiar instance, but whether the differences
between the brilliancy of males and females be small or great, the
chicks resemble the duller hens.

The likeness between the chick and the duller sex occurs even in
those rare and curious cases in which the females are more brightly
coloured than the males. Adult cassowaries have a deep black
plumage, but the naked skin of the head, neck and legs is often
coloured in brilliant and fantastic ways, the coloration being much
more brilliant in the females, and in this case the young birds
resemble the males. In some of the curious little button quails, or
hemipodes, the sexes are alike, but in most of them the females are
decorated with reddish collars and other conspicuous patches and
marks, whilst the males are more dully coloured. The chicks in their
young plumage resemble the males. The female painted snipe of
Africa and Asia has a brown head with ruddy marks on the sides of
the face and round the neck, whilst the back is brownish-green with
dark flecks and bright golden-yellow “eye ’’ markings. The male
is a duller bird with almost no trace of the reds and golden-yellows
that light up his partner. The young birds are like the males. In
the so-called grey phalarope, a plover-like bird which occasionally
visits England in spring and autumn, but which breeds in the far
north, the female is conspicuously brighter in her breeding plumage.
The breast and under parts are bright chestnut in colour, whilst the
head, back and upper part of the wings and tail are glossy black, the
IIo CHILDHOOD OF ANIMALS

individual feathers being margined with yellow-gold or vivid white.
The male is a pale image of his mate. In the eclipse plumage the
sexes are much alike and very like the eclipse plumage of the allied
red-necked phalarope. The ground colour is a greyish-white, whilst
the upper parts are less glossy and paler, with the bright margins of
the feathers very inconspicuous. The young birds are paler than
the males, and more closely resemble the eclipse plumage.

The best-known instances of the changes to “ eclipse ’’ plumage
are found in the ducks, game birds, waders, herons, some of the
tanagers and the weaver-birds. The little weaver-birds show
almost every degree of likeness between the sexes; in some cases
the males are very brightly coloured and the females dull, in others
the colouring of the two is nearly alike. They pass into a dull
eclipse and remain in that condition for nearly six months, and then
assume the breeding colours again. The young birds are always
more like the hens and the eclipse stages, the brilliant blacks,
scarlets and purples being absent and replaced by mottled brown.

When both sexes are alike, the young in their first true plumage
are usually unlike the adults and are much duller and browner,
Examples of this occur in almost every group of birds. Sometimes
the change from immature to adult plumage occurs at a single moult ;
sometimes gradually over two or three years as in the gulls (see
Plate VIII, p. 162), the feathers changing by almost imperceptible
stages ; sometimes, as in birds-of-prey, it takes a number of years,
mottled and striped plumages being replaced by feathers with trans-
verse bars, then by self-coloured feathers, and the general shade of
the whole plumage getting darker. In the king penguin the brownish
down is replaced by the first immature plumage, when the birds are
nearly a year old. The crown of the head has a pale grey centre, the
neck patch is light lemon-yellow instead of the bright golden-yellow
of the adult, and there is less distinction between the back and the
ventral surface, the general coloration being a pale brownish-grey,
lighter on the under surface and darker on the back. Many sea-
birds are vividly patterned when adult, the under side being usually
quite white, the upper surface black, or a shade of pearly-grey with
black markings, or the whole bird, as in the case of the gannet, may
be white except for the black tips of the wings. The young in their
first plumage are nearly uniformly covered with shades of mottled
brown. So also ibises and storks, which when adult are white, or
brilliantly marked out with white, brown and black, wear a juvenile
garb of mottled and spotted brown. The down of young pelicans is
COLOURS AND PATTERNS OF BIRDS | 111

replaced by a uniform of brown before the brilliant livery of the
adult is assumed. The American scarlet flamingo when adult is
clad in scarlet and pink; the European white flamingo is white
with scarlet on the under surface of its wings. Young flamingoes about
two months old, with their beaks still nearly straight, have shed the
nestling down, but replaced it by a plumage which is almost uni-
formly grey, with the faintest traces of scarlet on the wings. In
birds-of-prey, adult males and females are so alike that it is most
difficult to distinguish them, although the females are usually
larger. The young, after moulting off their down, assume a set of
successive liveries in which there is a slow change from dirty white,
and mottled and spotted brown, to the brilliant blacks and whites
and blue-greys of the adult. So also in owls, where the sexes are
alike, the young differ from them, being usually paler, browner and
more barred, striped and mottled. In doves and pigeons, where the
sexes are alike, the young are usually more mottled, and especially
in the brightly coloured fruit pigeons are browner and with little
trace of the metallic sheens and brilliancy of the adults. The
common cuckoo is almost exactly alike in the two sexes ; the back
is uniformly ashy grey with small white spots on the darker tail, and
the under parts are white with dusky bars. The young, in immature
plumage, which they wear until they are as large as their parents,
are clove-brown above, and the feathers of the wing and tail are
barred and mottled, so that the general appearance is strikingly
different from that of the adult. The young of thrushes and fly-
catchers are clad in a completely spotted plumage, but the adults
are generally uniformly covered above.

When the sexes are alike or nearly alike, and especially when they
are brilliantly coloured, the young in a few cases may be like the
adults. In kingfishers the young are only a little less brilliant than
the adults. In orioles, where the adults are usually very brilliant,
the young are only a little less brilliant. In parrots almost every
condition from dull to brilliant young is found. In those such as
the nestors, where the coloration is never very brilliant, and where
there is a good deal of mottled brown in the plumage, the young are
conspicuously browner and more mottled. In other parrots, the
first true feathers may be as bright as those of the adult. In
the Eclectus parrots, where both males and females are brilliant,
but the males are green and the females red, this distinction
between the sexes is carried backwards, so that a young male, still
clad in purplish down, shows the brilliant green wings of the adult.
Liz CHILDHOOD OF ANIMALS

Although the instances I have given are the merest samples
of the fertile diversity of colour and pattern displayed by birds,
they show the chief types of relation between the characters
of males, females and young. It is possible to build up from them
a general picture of a process that appears to have been going on.
The older or ancestral types of birds displayed a plumage generally
brownish in colour with little difference all over the body, and with
patterns of spots and stripes and mottlings. At first the colora-
tion of the young and of the adults in both sexes was more or less
alike. Next, during the breeding season, the males began to assume
brighter colours, and when the breeding season was over relapsed
again into the dull coloration of their ancestors. In such a stage,
the males in eclipse, the females and the young were all much alike,
and traces of this condition survive in many existing groups. Next,
the bright breeding plumage was partly assumed by the females as
well as the males, but after the breeding time was over, both relapsed
to the ancestral eclipse condition. In this stage, the males and
females in eclipse and the young were like the ancestors. This
stage too is retained by many birds, and the curious cases where the
females have shot ahead of the males is only another variation of
it. Next, the breeding plumage was retained for a longer and
longer period, for half the year as in the weaver-birds, for all but a few
weeks as in game birds and most of the ducks, or for the whole year
as apparently in the South American tropical ducks, in kingfishers
and in parrots. There are traces of its gradual suppression; in
some of the game birds and in some of the tanagers, for instance, the
eclipse is represented by only a few feathers. When the eclipse has
been suppressed, it is only the young birds that retain the dull
ancestral plumage, and there is every stage of the suppression even
of that in the young.

And so the general trend amongst birds and mammals alike has
been from dull colours and mechanical patterns to brilliant and
fantastic garbs. The obscure dusky browns and greys may be com-
pared with the coal-tar residues from which chemists have separated
and distilled a series of vivid aniline dyes. In a sense, all the
shining colours of the rainbow lie concealed and confused in the
turbid mother-liquid, and it is only by separation and recombina-
tion that the individual colours are obtained. And so in a sense,
perhaps rather an exact sense, the obscure hues of primitive animals
are accidental residues or waste products of the living chemistry of
the body, and it is only when they have been split up and separated
COLOURS AND PATTERNS OF BIRDS re

that they appear as brilliant patches of distinct colours. And thus the
hues that depend on structure, the metallic sheens and the irides-
cences and blooms point to a greater delicacy of texture, a refine-
ment of minute structure, a replacement of the casual effects of
growth by more finely tempered products. In pattern, the primitive
spots and mottlings may be and probably are no more than an
accidental result of the composite nature of the skin, and of the
changes in the rate of growth, as the physiological activities of
the body rise and fall. These are replaced by patterns of a less
accidental character. Spots grow into stripes, or spread into patches ;
some areas expand, others are suppressed. Flaps and outgrowths
of skin, ridges and patches of hair, tufts and mantles of feathers
expand and lie over their neighbouring areas, producing arrangements
that do not conform with the primitive contours and uniform
characters of the body.

The set of changes has been attended and made possible by an
increase in the vigour of the body and a heightening of the vital
activities, so that respiration, excretion and all the chemical changes
in the living laboratory have become more exuberant. The changes
are an expression of surplus vital activity, for ifanimals are to succeed
they must on the average be a little more vigorous than is absolutely
necessary to attain their purposes. Now and again a successful
runner may faint at the goal, but in most cases he can run a little
beyond it. In the affairs of animals, as of men, some reserve is
requisite. And so it is natural to find the beginnings of more
brilliant colour and more vivid pattern associated with the breeding
season, for in the breeding season the strength and vigour of animal
life are most acute. It might be argued, as not a few naturalists
have urged, that the cumulative beauty of animals is in itself acci-
dental and inevitable, the mere result of their increasing strength and
vitality, and that there is no need to try to account for it by theories
of natural selection.

Darwin was always careful to insist that natural and sexual
selection were not the actual causes of the wonderful patterns and
colours that are displayed in the animal kingdom. They were out-
crops of the constitution of the body, by-products of its activities,
and what happened was that when a colour or pattern that was useful
appeared, it was favoured in the struggle for existence, or in the eyes
of choosing mates, whilst colours and patterns that were harmful or
that were displeasing were slowly eliminated. Ido not think it can
be doubted that in many cases the spottings and mottlings and dull

C.A. H
II4 CHILDHOOD OF ANIMALS

colours of young birds and mammals make them less conspicuous,
and that it may be for this reason that they have been retained in so
many animals, in females that have to lie hidden during the breeding
season, and occasionally in adults. They have not been created for
the purpose of concealment, but they have been retained because they
existed and were useful. So also the obliterating effects of counter-
shading, the replacement of primitive patterns by ruptive patterns,
and of dull colours by brilliant hues, may have come about in the
natural course of physiological events and been retained where they
were useful or harmless.
CHAPTER VIII
LIMITATION OF FAMILIES

ELEPHANTS may live until they are at least a century old, and do
not begin to breed until they are well over twenty years of age.
They are probably the slowest breeders of all animals, and a pair
living to their full range of life under the most favourable conditions
would not bring into the world more than six young ones. None
the less, as Darwin calculated, if we could suppose that all the
descendants of a single pair of elephants were to live to their full
time of life, and to produce their six offspring, then at the end of
the fifth century the single pair of elephants would be represented
by over fifteen millions of living descendants. At the other end
of the scale we may place a fish like the turbot, which can produce
as many as fifteen million eggs in a season. I do not know how
long it will live, if it escape being caught, but certainly it is capable
of living a good many years. If all the descendants of a single
pair of turbot were to survive, even the enormous area of the
oceans would soon be filled with a solid mass of fish. A pair of
London sparrows are able to rear three or four clutches of eggs in
the course of a year, and each clutch contains from five to six eggs.
The prolificness of animal life is enormous. Whether animals live
a short time or a long time, whether they produce many or few
young in a season, a sum in arithmetic shows that the air, and the
surface of the earth, and the waters could soon be filled with the
incredible swarms of progeny.

And yet we know that on the whole the relative numbers of
different species of animals remain stationary. Now and again
there is a grasshopper year, or a vole year, or a wasp year, when
the destructive forces seem to have been swamped by natural
increase. Some species of animals, such as man himself, are steadily
gaining ground ; others, like the bison in America or the antelopes
and zebras in South Africa, are disappearing ; but on the whole
the balance of life is preserved and, with occasional fluctuations,

species neither gain nor lose very much in numbers.
115
116 CHILDHOOD OF ANIMALS

It follows of course that the natural rate of mortality must be
very high. If each pair of sparrows tend to be turned into about
twenty sparrows by the end of the year, and yet the total sparrow
population does not increase, eighteen out of twenty must die
every year—that is to say, the sparrow death-rate must be about
ninety per cent., the normal human death-rate in London being
only about one and a half per cent. per annum. The death-rate
amongst elephants must be smaller; that amongst turbot higher.
Anyhow, it is plain that death takes a heavy toll of all living things.

Death falls most heavily on young animals. Physically they are
more feeble and more readily succumb to extremes of heat or
cold, to starvation or over-eating, to drought or rain, and to disease
of all kinds. But their plain destiny is to be eaten. Young animals
are more tender and succulent than old ones. Their fur, feathers,
scales, bones and other hard parts offer less resistance to the teeth
or claws and other biting and grasping organs, and offend the
stomachs of their captors less than those of full-grown animals.
They are not only a more attractive but an easier prey. They
cannot fight or struggle much, they have feebler powers of escape,
and less cunning and resource in avoiding their enemies. They
form a great part of the food-supply of the world.

The ultimate source of the food of all animals is green vegetation.
A vast expanse of verdure, trees, shrubs, grasses, ferns and moss
covers almost the entire surface of the land from the tops of the
mountains down to the edges of the sea. All this green vegetation
is actively building organic food-material from the inorganic
elements of the air and the soil. And so on the land vegetarian
animals are more prolific and abundant than carnivorous creatures.
Plant-eaters like sheep and cattle, deer and antelopes, rabbits and
kangaroos are found in huge numbers and multiply at incredible
rates. So also seed- and fruit-eating birds are more numerous
than carnivorous birds; grasshoppers, locusts and vegetarian
beetles than their carnivorous allies. But all these are preyed upon
by carnivorous mammals, birds, reptiles and insects. In the sea,
on the other hand, most of the animals are carnivorous. The
birds that live on the ocean, terns, gulls, petrels, cormorants,
are very numerous indeed, and the clouds of sea-birds in their
breeding-places recall the dense vegetarian population of the land.
These sea-birds are all carnivorous ; most of them are fishers, and
others, like the petrels, scoop up the small crustacea from the
surface of the waves. Seals pursue fishes; polar bears live on
LIMITATION OF FAMILIES Ir?

seals; sea-elephants and walruses live on shell-fish; whales,
dolphins and porpoises all live on sea-animals, and many of them
are fierce beasts of prey. Most fishes are carnivorous, and one
has only to think of the shoals of herring and mackerel, the wall-
like masses of codfish and the great hauls of sardines to realise the
enormous animal-eating population of the sea. Most of the lower
forms of life are carnivorous. The gardens of the tropic island
sea-bottoms, with their brilliantly coloured, flower-like polyps, are
composed of animals that live on other animals almost exclusively.

A small portion of the ultimate food-supply of the sea consists
of the flotsam and jetsam from the land, of waste matter washed
down by the great rivers. But the main source is to be found
in the sea-water itself. If the open sea seems at first a barren waste,
the tow-net shows that it contains myriads of small animals.
These are the larve of innumerable creatures that live on the shore
or on the bottom, together with countless wanderers that have no
fixed abode, but drift all their lives with the ocean currents.
Amongst them are great numbers of small plants, like the
protococci that form the green scum on pools of rain-water, or the
diatoms familiar to every one who uses a microscope. These, in
the fashion of terrestrial green plants, build up food-material from
the inorganic salts in the sea and from the gases of the air. Little
animals live on them and are in turn fed on by larger animals. In
the depths of the ocean, where no light penetrates, green plants
cannot live, and the food-supply must be derived from live or dead
animals that rain down from the surface.

And so on land and in the sea, in the air and in the waters, living
creatures are ceaselessly devouring other living creatures, and the
feeble and succulent young are the readiest victims. The more
powerful carnivorous animals seem to rejoice in their strength
and skill, and many of them destroy far more victims than they
require for food. Others are extremely voracious, and appear to
have no limit to their capacity for digestion or to their appetite.
If we reflect on the dangers from accident, disease and the host of
hungry enemies, the wonder seems to be, not that species occasionally
have become extinct, but that any have maintained their existence.

The most common device in the animal kingdom to meet the
immense destruction of life is for the young to be produced in
enormous quantities. In the sea especially, where most animals
are carnivorous, the ripe females are bloated with a great burden

. of eggs, to be counted by millions or thousands or hundreds, and
118 CHILDHOOD OF ANIMALS

large tracts of water become changed in colour because they swarm
with innumerable multitudes of tiny embryos. Sea-anemones
and jelly-fish, starfish and sea-urchins, the various tribes of worms,
crustaceans and molluscs, sea-squirts and fishes turn adrift a huge
and uncared-for progeny out of which a few lucky individuals
reach maturity. We know the vast broods that many insects
produce, we have seen a nettle black with the caterpillars of a
single butterfly, or a carcass pullulating with the maggots of
one blow-fly. Although amongst the higher animals we count
large families by sixes and tens, instead of by hundreds and thousands
or millions, we know the amazing fertility of many small mammals
and birds.

To produce a large family, making little provision for it, is a
wasteful and improvident method of maintaining the species. To
limit the number of the young, to lavish on them parental care and
not to throw them on their own resources until they are well fitted
to make a brave fight against the troubles of the world, are surer
means of maintaining the numbers of the species and enabling it
to reach a higher level of efficiency. Devices of this kind have been
adopted in almost every group of the animal kingdom, but become
more universal and more complete as the scale of life is ascended.
Not only are the numbers in the family reduced, but the period of
youth becomes longer. The protected young are no longer at
once absorbed by the immediate problems of life, by the struggle
for mere existence. They form in each division of the animal
kingdom a kind of aristocracy with leisure for education and training,
and with the-opportunity of modifying instinct by practice. The
word family in their case acquires a new and real meaning. It no
longer is a name simply for the offspring of a single pair of parents,
but comes to imply an association of brothers and sisters, of young
and parents living together in a new relation, not merely temporarily
united by the attraction of sex, but forced to live together in some
kind of harmony, with some degree of mutual toleration. The
appearance of the family provides opportunity for developing the
social habits which are the foundation of the higher sides of
mental and emotional life. Co-operation, friendship and love
which is not sexual attraction find their first beginnings in limitation
of the numbers of the young and in the association of young and
old in the family tie.

In the lower animals the limitation of the numbers of the young
and the institution of parental care are often associated with
LIMITATION OF FAMILIES IIg

specially hard conditions, and are found amongst creatures that live
in very cold water, as in the polar regions, or in fresh water, where
the strong currents and rapid changes of temperature are hostile
to the feeble young, or in the strenuous and, storm-tossed life of the
shore. It may well be that of the multitude of young produced,
only those that accidentally remained with their parents survived,
and that afterwards the total number was gradually reduced and
the arrangements for retaining the young with their parents made
more perfect. In most of the sea-urchins enormous numbers of

eggs are discharged every season ; the number in the common edible
form sold in the markets of the

south of France and Italy has
been calculated at twenty millions.
These eggs are fertilised in the
sea and the young embryos drift
without any help or protection
from their parents. In some of
the urchins from the Antarctic
seas, Sir Wyville Thomson found
that there were little shallow
pouches on the outside of the
Shell or test of the female, and
that the spines bordering these
were long and curved over to Fic. 26. A Sea-urchin carrying its
form basket-work lids. The eggs, 7°" pee tae eae

comparatively few in number, were passed into these pouches and
there developed directly into small urchins, which thus enjoyed
the security and protection given by the mother until they had
reached a considerable size (Fig. 26). So also the most common
sea-cucumbers produce eggs in enormous numbers, and these
develop into unprotected embryos in the water. In a sea-
cucumber from the Falkland Islands the two rows of tube-feet
(the bivium) along the dorsal surface are rudimentary, and not
used for locomotion in the females; along these a dozen or so
of little animals are attached, looking like a row of yellow plums,
and remain there until they are nearly fully grown and able
to live the independent lives of the adult. Although in most
starfish and brittle-stars large numbers of young have to encounter
the huge mortality of a free life in the waters, in others only a few
are produced, and creep about on the body of the mother (Fig. 27)
or develop in a brood-pouch formed on the outer surface of her body.

 
120 CHILDHOOD OF ANIMALS

In most of the marine worms very many eggs are laid, and
these develop into free-swimming larve, subject to the usual
destruction by innumerable foes. In a few the number is re-
duced and the young are carried attached to the body of the
mother, sometimes contained in a pair of brood-pouches on the
under surface of her body. In terrestrial and fresh-water worms,
such as the common earthworm, the number of young is reduced,
and these are enclosed in little protective cases or cocoons formed
by the poten and suspended to water-weeds, or hung up against
the wall of the burrow.
Leeches arrange for
their young in a similar
fashion, but there are
some in which the eggs
remain attached to the
body of the mother,
to the under surface of
which the young leeches
fix themselves when
they are hatched, by
their suckers, and so
secure protection.

All the crustaceans

have gone a consider-

Fre. 27 Pines Taoueeny ME able way in the reduc.

tion of the number of
eggs produced and all of them display at least the beginnings of
parental care. In a very few, including some of the fish-lice,
the eggs are attached by the mother to water-weeds or stones.
In most they are carried about by the female in a brood-pouch,
or attached to the legs or to a special chamber formed from
the flap that protects the external gills. When the eggs hatch, in
most cases free-swimming larve emerge, and these without further
aid from the parents are transformed to the adults by a series of
moults. During their larval life, however, prodigious numbers are
destroyed, for crustacean larve form a most important part of the
food-supply of fishes and aquatic birds, and the different groups
supply many cases of a still greater protection of the young by the
parents, with reduction in the number produced and a much higher
percentage of success in reaching adult life. The summer eggs of
the little water-fleas (Cladocera) are hatched in a brood-pouch

 
LIMITATION OF FAMILIES 121

under the shell on the back, and in some cases are fed by a nutritive
juice which reaches them froma large blood-space. In many others,
the eggs are carried in pouches attached to the body of the parent,
or are suspended to her legs. In all these small flea-like crustaceans,
however, the development is indirect, and at least some meta-
morphoses are gone through. In the sandhoppers and slaters the
numbers of the young are still further reduced, and the embryos,
"carried by the mothers in brood-pouches, are fed and protected
until they have almost completely attained the adult structure.
In the higher crustaceans, such as shrimps and prawns, crabs,
lobsters and crayfishes, the eggs are rather numerous, and are
cemented to the under surface of the body of the mother, forming
the familiar ‘‘ berries ’’ which in prawns, crabs and lobsters turn
red on boiling. In those that live in the sea, when the eggs hatch,
the larve leave the mother and have to fend for themselves. In
the fresh-water forms, however, such as the familiar crayfish, the
eggs are much larger in proportion to the size of the animals, and
are much less numerous. The complete development takes place
before hatching, whilst the egg is still carried by the mother, and
when the young creature emerges it is almost a perfect miniature
of the parent. It enjoys the protection of the mother for a still
longer period, clinging to her with its pincers.

Scorpions and spiders are terrestrial, air-breathing creatures of
high organisation, and show many instances of elaborate precautions
for the care of the young, and of a resulting reduction in the numbers
of the brood. Scorpions are the larger, more powerful and better
armed, and in them the process has gone furthest. The eggs are
hatched inside the body of the mother, and each brood consists of
no more than about a dozen individuals, which are born two at a
time. From their first appearance they can be recognised as little
scorpions, differing only in size, in paler colour and in a few minor
details from their parents. They at once find their way to the back
of the mother, and the whole family is carried in this way for some
weeks, until the young creatures have gone through several moults
and become large enough and strong enough to look after themselves.
During this time they enjoy protection, for a scorpion is a formidable
creature with few enemies sufficiently daring to attack it. The
young feed on scraps of the spiders, cockroaches and other insects
which the mother catches and slowly picks to pieces.

Spiders are far from having reached the economy of breeding
habits shown by scorpions. The young are always hatched outside
122 CHILDHOOD OF ANIMALS

the body of the mother, and although they are plainly spiders
at their first appearance, they go through a number of moults
before they are capable of independent life. They are fragile and
delicate little creatures and suffer great destruction from storms of
wind and rain, from drought and floods, and although the numbers
produced at a brood are very much reduced from the enormous
quantities found among marine animals, they are often large. In
some of the spiders belonging to the same group as the garden spider,
which spins its huge geometrical snares in autumn, as many as from
six hundred to two thousand eggs may be laid by a single female.
The numbers are proportioned to the special difficulties to be met,
and in some of the spiders that live in the safe retreat afforded by
‘dark caves there may be no more than four or five eggs.

Maternal care begins before the eggs are laid. Most female
spiders spin a little web of silk, deposit the eggs on this and then
‘cover them up with another layer. The egg-bags, or cocoons,
are often distinctively shaped and coloured. Those of the large
garden spider are globular, bright yellow in colour and almost as
wide across as a shilling. Sometimes the cocoons are hidden in a
natural shelter, sometimes suspended to the under surface of a
leaf, or even hung up in the neighbourhood of the web, and the true
cocoons may have woven around them curiously shaped cases of
thick resistant silk, which further protects them against the
weather. The hunting spiders, which pursue their prey on foot,
running swiftly over the ground and springing on insects with
great bounds, usually fasten the globular cocoon by a firm thread
to the under surface of their body and let it bump along after them.
The nests, burrows and other retreats that spiders excavate or
spin are usually for their own protection and not specially for the
young. But the little English spider that makes a tent-like
dwelling of soft fluffy threads and is found in almost every bush
and shrub in summer, places her green cocoons in her own tent,
and the young when they come out live with the mother for some
weeks. The large water-spider builds a similar dome of silk under
water, carries down globules of air entangled in the hairs of the
body, and sets them free under the dome until it becomes an anchored
diving-bell, within which the eggs are laid and the young hatch
and live, until they turn out to make their own retreats.

When young spiders hatch they are pale in colour, and as
they are covered with a thin membrane, can neither spin nor eat.
After a few moults they differ from the parents only in size. Until
LIMITATION OF FAMILIES 123

two or three moults have becn gone through, and this usually
occupies about a week, the young spiders remain near the cocoon
or the mother. Amongst those that spin geometrical webs,
the young cling together in a great yellow ball, but if this be
disturbed or touched, they suddenly scatter into a golden mist,
each little spider shooting out at the end of a long, almost invisible
thread of silk, and then when the disturbance is over, they re-
assemble. This period of dwelling together in amity does not
last long, for as soon as the spiders are able to feed they assume
the fierce habits of their race and are ready to fall on each other.
At first, however, they settle down near their original home, each
making its own web.

When the young of the wolf-spiders hatch, they soon leave the
cocoon. The broods are much smaller in numbers, as the mothers
could not drag about a heavy weight, and the young creatures
climb on the back of their mother and accompany her on her
hunting expeditions.

Sooner or later, however, spiders have to disperse to avoid the
reawakened instincts of their mother and the fierce attentions of
their hungry brothers and sisters. Many of them do it by a curious
device, making use of the wind like the winged or tufted seeds of
plants. Ona fair but windy morning they climb up to the highest
point available, to the topmost bar of a fence, to the edge of a high
wall or to the extreme twigs of bushes. There they raise them-
selves on the ends of their legs with the abdomen held erect and
pointed backwards away from the wind. Then little tufts of delicate
silk are shed out from the spinnerets and float in the breeze until
they are long enough and have enough surface to carry the spider
from its support. The caprice of the breeze determines the course
and distance of the flight, but just as a spider can haul in the thread
which binds it to a spot from which it has dropped, so when it is
floating it can roll up its sail, piece by piece, until it descends
to the ground.

Insects in every stage of their lives suffer greatly from the
inclemency of the weather, the ravages of disease, and the attacks
of other insects, of spiders, and especially of frogs, reptiles, birds
and mammals, many of which live almost entirely on an insect
diet. Some insects are extremely prolific, but none the less, especially
in the higher members of the higher groups, the old thriftless method
of large broods left to take their chance in the world is replaced by
smaller broods for the safety of which great precautions are taken.
124 CHILDHOOD OF ANIMALS

It is a singular fact that in by far the greater number of cases
the provision for the young is made by parents destined never to
see their offspring, and who are nearly always dead even before
the eggs have hatched, and it is therefore only in a very few cases
that there is an actual association between the hatched young and
their mothers. The provision seldom extends to more than select-
ing or preparing a suitable place in which the eggs may hatch and
where the larvee when they emerge may have the proper surroundings
and the proper food.

Among the orthopterous insects the eggs are rather numerous,
and are frequently scattered on the ground without any pre-
cautions. The common earwig, however, has been observed collect-
ing her eggs with her mandibles, arranging them in heaps and
brooding over them. When the young emerge, the mother takes
no further interest in them, and after a few moults they are com-
pletely like the adult. Cockroaches enclose the small number
of eggs they produce in a cocoon, which is formed in the interior of
the body. When the cocoon leaves the body, it is carried about by
the mother for some time and then hidden in a chink, or, in the case
of the common cockroach, most frequently just under the edge of
a carpet or sheet of oil-cloth. The praying mantis constructs a
chambered egg-case, which it attaches to wood or stones. Lear
insects and stick insects deposit very large numbers of eggs
almost at random, and the young soon after they are hatched
usually have the appearance of their parents, although some, such
as the Ceylonese stick insect, go through remarkable changes of
shape and colour. Stick insects kept in a glass vivarium case in
the Insect House of the London Zoological Gardens produced an
enormous number of young. These began to migrate when they
were so small that they could pass through the perforated zinc
back of their cage, or squeeze between the door and its hinge, and
wandered all over the Insect House. The females of the large
brown locusts and grasshoppers have several hard projections at
the tip of the body, and with these excavate little chambers in the
ground in which the eggs are laid along with a fluid exudation that
sets to form a resistant lining to the chamber. The eggs of these
locusts are much sought by other insects, especially beetles, which
are able to penetrate the hard chambers. The young of the
migratory locust go through a number of colour changes, the
meaning of which is unknown, soon after hatching. On leaving the
egg the larva at once moults, and the new skin is green at first, but
LIMITATION OF FAMILIES 125

then becomes brown, and in a few hours is black. In six days
there is a second moult, after which the young insect is black, with
spots and bands of white, and coloured streaks along the posterior
end of the body. In about another week there is another moult,
and the coloured streaks expand to form rosy patches. In less
than three weeks there have been six moults, with successive
changes from pink to yellow and blue, and the insect in its final
form is chiefly black with blue and rosy marks. Female green
grasshoppers have nearly always a long ovipositor at the tip of
the abdomen, and with this dig a shelter for the eggs. Crickets
have a long ovipositor, and do nothing for their young after the
eggs have been laid in a suitable hole. The mole-crickets make
burrows for themselves underground, using their strong spade-like
front legs for the purpose, but the female also constructs a special
chamber in which about a hundred eggs are laid and where there
is a space for the newly hatched young to lurk. The clear-winged
stone-flies, dragon-flies and may-flies simply drop their eggs into
water, and there the larve, as J have described in an earlier chapter,
live a totally different life from that of the adults.

The termites, or so-called white ants, which, however, are related
to may-flies and dragon-flies rather than to ants, show one of
the most remarkable developments of family life in the animal
kingdom. The conditions differ a good deal in different species.
Each colony is really a patriarchal family, the descendants of a
single pair living with their parents in a community and playing
different parts in it. One of the simplest cases is that of a European
termite the habits of which have been studied in Sicily. A winged
pair take up their abode in a dead or decaying tree, living on the
rotting wood and hollowing out chambers and burrows. They
reproduce slowly, being surrounded by fifteen or twenty young
after the first year, but more rapidly afterwards, and in a few years
the family may reach as many as a thousand. The eggs that
hatch out produce larve which are at first true males and females.
Some of these develop slowly, and in rather more than a year
become perfect winged insects, and leave the colony in pairs to
found new colonies elsewhere, after having spent their youth, so to
say, as servants in their parents’ house. Other individuals develop
nore quickly, but when fully grown are blind and wingless. Their
ceproductive organs remain in a condition of arrested development,
and their jaws and heads become of enormous size. In the more
highly developed colonies, these individuals, known as soldiers, are
126 CHILDHOOD OF ANIMALS

fed differently, and it appears as if the peculiar food they receive
were the stimulus to their different mode of development. The
use of the soldiers is to defend the colony, by blocking up apertures
with their enormous heads and powerful jaws, threatening, attack-
ing and driving away enemies. In their youth these warriors
have undergone a kind of forced conscription, but they have been
so shaped and trained for their special functions that they cannot
resume the normal life and normal functions of perfect individuals.

In some of the numerous African species of termites which
construct chambered dwellings many feet high, the colonies are
much more elaborate, but remain essentially single families, all
being the descendants of one pair, the king and queen. These lose
their wings, and the queen becomes enormous in size, and lays
almost incalculable quantities of eggs. The larve that hatch out
are at first much alike, but, owing partly to differences in food,
some remain small, blind and wingless, with arrested sexual organs,
and live their whole lives as workers, constructing the chambers,
providing the food, tending the king and queen, soldiers and young.
Others also remain blind and wingless, but grow several times as
large as the workers, and develop enormous heads with strong jaws
or with peculiar snout-hke protrusions from the forehead; these
also remain in a condition of arrested sexual development, and act
as soldiers or warriors, being useful only for the defence of the colony.
Finally, other larve develop into perfect winged insects, male or
female, and leave the colony in great numbers, most of them
perishing, but a few becoming the founders of new colonies. These
elaborate communities may consist of many thousands of individuals,
but they remain a single family, and it is believed that, whilst
occasionally a new king and queen may be reared, in most cases
the community perishes when the original founders die.

The saw-flies, like most insects, do little more for their young
than deposit the eggs in suitable places. The females are pro-
vided with a pair of sharp, toothed blades, placed on the lower side
of the abdomen, by which they saw into the tissues of plants and
prepare a place in which the eggs may be laid and the newly hatched
larve find food. In one rare case, however, maternal care goes
further. The female deposits her eggs, about eighty in number
(and this is much less than the usual number in these prolific
insects) on the leaf of a eucalyptus, then watches over them until
they hatch, and remains for some time with the young larve,
standing over them with outstretched legs, and so warding off
LIMITATION OF FAMILIES 129

enemies. The gall-flies are provided with a delicate ovipositor,.
and by means of this the females pierce the tissues of plants to.
deposit their eggs. Some of them, however, use their weapons to.
insert their own eggs into the actual eggs, or more often the soft larve,
of other insects, and the young when they hatch are thus provided.
with a living prey. The ichneumon-flies have similar habits.
They prey chiefly on the caterpillars of butterflies and moths, and
when they have found a suitable victim, which may be many
hundred times larger than themselves, swoop on its back, pierce
the body with the ovipositor and leave their eggs in it. The larve
thus hatch out in a favourable and protected position and eventually
devour their unwilling host. In many cases their ravages are so.
timed that the caterpillar is not killed before it has pupated, and
its parasites then go through their own pupation within the chrysalid.
Those who breed butterflies and moths have to take sedulous.
precautions to keep off ichneumon-flies from the eggs and cater-.
pillars they are rearing, and none the less often find that at the
time when the butterfly should appear there comes out only a
swarm of little flies.

The females of the gaudy little ruby-flies haunt places occupied
by solitary wasps. When one has discovered a cell with a young
wasp larva in it, together with the store of caterpillars that
the wasp has placed for the benefit of its own grub, she places
a few of her eggs in it, and the larva devours not only the
wasp-grub but the caterpillars stored for the latter. These
ruby-flies which have thus learned to provide so well for their
young lay very few eggs, and of those that are laid usually only one
hatches out.

The larve of bees are soft, legless grubs, and are placed in cells.
constructed by the mothers themselves in the case of the solitary
bees, or by the arrested females known as workers in the social.
bees, whilst in some parasitic bees the mothers deposit the eggs in
cells constructed by other bees, and the parasitic grubs hatch out.
more quickly and devour the food prepared for their host. In the.
solitary bees each cell is packed with a mixture of honey and pollen
collected by the mother ; in the social bees the food is collected by
the workers, who feed and tend the young.

The female solitary wasps construct a cell for each egg, in which
they store from eight to a dozen caterpillars, which are paralysed
by the sting and so remain fresh and alive until the wasp-grub 1s
ready to devour them. Among the social wasps, each colony or
128 CHILDHOOD OF ANIMALS

nest is really a family founded by a single female which has
hibernated. In spring she selects a suitable locality and lays the
foundation of the nest, depositing an egg in each of the first few
cells. The grubs hatch out quickly, and then the female devotes
all her attention to feeding them, bringing at first sugary material
which she collects from flowers or from any store she is able to rob.
When they are a little older, she chases and captures living insects
of different kinds, breaks their bodies into a pulp by her strong
jaws and supplies this animal diet to the growing young. The
first set of young mature into workers, which are really imperfect
females, and these at once devote all their time to improving and
enlarging the nest, and to foraging for and tending the successive
series of eggs which the queen continues to lay. The fossorial
wasps are all carnivorous and hunt and collect insects, caterpillars
and spiders for the use of their grubs. The females do all the work
and never live in communities, but make separate cells of clay,
burrows in soft soil or tunnels in the tissues of plants, in which
to place their eggs and store of victims. The Pompilide prey
specially on spiders, and often attack large and poisonous species.
They watch for them at the entrance of the holes in which the
spiders lurk, and if they have an opportunity, pull one out by the
leg, at once sting it between the poison fangs so as to paralyse these
dangerous weapons, and then sting again in the soft place where
the abdomen joins the front part of the body, so reducing the spider
to immobility. The wasp then makes a burrow and deposits in it
the helpless spider and an egg.

In the communities of ants, which, unlike those of wasps and
bees, last for a number of years, there are usually more than one
queen or fertile female. The eggs hatch out into little grubs, which
are fed and tended by the workers with a care and intelligence far
surpassing the qualities displayed by any other invertebrate
animals. The grubs are moved from place to place in the nest
according to temperature or moisture, are kept clean, and are
frequently carried above ground for an airing.

Beetles as a rule lay a considerable number of eggs, and do
no more for the next generation than choose a suitable place for
the larve. In the dung-beetles special provision is sometimes
made. The common scarabeus beetle of south Europe buries dung
for its own consumption, but also accumulates a large mass in a
subterranean chamber, in the middle of which the egg is deposited.
In other dung-beetles, each female lays only three or four eggs in
LIMITATION OF FAMILIES 129

the course of the season, and watches over her young until they
have matured. The great water-beetles spin cocoons of silk in
which the eggs are deposited, and suspend them to a leaf or water-
weed. The sexton-beetles bury the carcasses of small animals and
lay their eggs in them. Butterflies, moths and most of the true
flies and bugs present every gradation from the almost random
deposition of a very large number of eggs to the careful selection
of a food-plant or food-material on which the eggs are laid, the
number being then smaller. Occasionally the eggs are deposited in
burrows that are excavated in the tissues of plants or in wounds
made in the bodies of animals.

Many of the marine molluscs lay enormous numbers of eggs and
make no provision for the young. The common edible oyster
begins to breed when it is three years old, and the spawning season
lasts from April to August, beginning rather later in cold years.
The eggs hatch out inside the gill-chamber of the parent and emerge
as little free-swimming larve, and it has been calculated that
from three hundred thousand to six millions may be discharged
by one oyster in a single season. A very large proportion of the
embryos perish, for they die unless they succeed in finding
suitable ground to fix themselves within a day or two. Those
that adhere to some solid object, such as a piece of stone,
lose their cilia and begin to grow rapidly, being small oysters
about an inch across at the end of the first year and thereafter
increasing at the rate of about an inch a year. In the common
fresh-water mussel, although the number of eggs is still very
large, being from fourteen thousand to a million, development
has proceeded further before the embryos are discharged from the
gill-chamber of the mother. The ciliated free-swimming stage is
passed through before hatching, and for a few hours the tiny embryo
swims about inside its own eggshell, thus recalling the free-swimming
state of its remote marine ancestors. After hatching, the embryo,
still within the gill-chamber of its mother, grows into a peculiar
larva known as the glochidium, with a shell consisting of two
valves hinged together, with strong teeth on the free margin of
each shell and with a long, sticky thread protruding from between
the shells. These larve are then ejected by the mother into the
water, and they fall in masses to the bottom, the long, sticky threads
forming a tangled mass, like the web of a spider. Most of them
die, but if any small fish, attracted by the gelatinous mass of larve,
come near, then the glochidia become excited, flap their shells

C.A. I
130 CHILDHOOD OF ANIMALS

actively, and so straighten out the byssus thread. If one of these
threads touches a fish, it adheres, and the tangled mass, consisting
perhaps of many hundred larve, is dragged behind the fish. As the
fish wriggles about, some of the glochidia are sure to be brought in
contact with it, and any that do so at once seize hold firmly with
the toothed edges of their shells, snapping them tightly together.
Those that have laid hold of a hard spine soon die and drop off.
Those that have lighted upon one of the gill filaments or the fleshy
part of fin or tail cause a slight inflammation in the tissues of the
fish and by the growth of these become enclosed in a cyst. Within
this they live on the juices of their host, are carried about by it,
and go through the rest of their development until they are perfect
little mussels. In the meantime, just as a thorn that has not been
extracted is gradually sloughed out of the human skin, so the
cysts containing the mussels are set free from the fish, and the
mussels drop into the mud and begin the normal adult life of their
kind. The fish that are chosen as the walking nurseries and feeding-
ground of the young mussels are usually sticklebacks, but minnows
and loach serve equally well.

In very many molluscs, such as the common limpet, the eggs are
discharged directly into sea-water without any kind of protection
or provision for the young, and only a very small proportion of the
enormous numbers produced succeed in reaching adult life. In
others the numbers are much reduced and the eggs are enclosed in
special cocoons of various shapes, whilst a nutritive juice is placed
in the cocoon with them. In the common whelk these cocoons are
globular, and over a hundred of them, each containing about a dozen
eggs, are stuck together in a rounded mass. The embryos which
happen to develop first, however, eat their slower fellows, so that
only a very few actually leave the cocoons. Various devices, such
as the formation of floating rafts of mucus, often curiously shaped,
are adopted by other marine molluscs. Many of the fresh-water
molluscs fasten their eggs in strings to water-weeds, whilst a few of
those in the sea carry them attached to their own shells. Precisely
as such provision for the protection of the young becomes more
efficient, the number produced decreases. In Paludina, a common
English fresh-water snail, the eggs are developed inside the body
of the mother, and the young, comparatively few in number, are
not born until they are plainly young snails.

In the air-breathing land snails, which must be regarded as the
most highly developed members of the group, the eggs are rather
LIMITATION OF FAMILIES 131

large, sometimes enormous, have stout shells and enough food-yolk
for the nutrition of the embryo until it is fully formed. The numbers
are much reduced and the eggs are generally hidden in some
secluded place, in nests at the roots of plants, covered over with soil,
or wrapped in leaves on forest trees. In some of the snails of the
Pacific Islands only five or six eggs are laid, and these are preserved
in a special chamber near the mouth of the shell of the mother,
where they remain some time after they have hatched out as young
snails.

In the various invertebrate animals the limitation of families
and the provision for the young are chiefly economic in character.
The supply of food and the protection afforded the young during
their most tender stages have brought about a greater security
that the species will be maintained. Incidentally, however, they
have been associated with considerable changes in the mode of
growth of the young. As these have no longer to secure their own
living, it is possible for the mode of development to be more direct
and for various ancestral stages to be cut out. It has led, more-
over, to very important modifications of instincts. We think of
the care bestowed by parents, and especially by a mother on the
young, as springing from affection, but it happens often amongst
invertebrates that such care is devoted to offspring that the parents
will never see and exhibited by animals to which it is difficult to
attribute any emotions. The emotional quality of affection really
comes later than the duties and cares and devotion of maternity.
It is a consequence and not a cause of parental care. The modifica-
tion of instinct that it reveals is very striking. The first business
of any animal is to look after itself, to provide for its wants, to
satisfy its own appetites, and especially in the case of carnivorous
creatures to regard every living and moving thing as prey to be
seized and devoured. The mere toleration of the young by the
mother is a new beginning in life, and is the foundation of many of
the highest qualities displayed by the highest animals and by man
himself.

The relations of the young to the mother are less surprising.
They are a continuation of the organic relation by which the young
are born of the body of their mother, and they exist and become, so
to speak, a habit before the individuality, the physical powers and
the senses and aptitudes of the young are really awakened. And
so in the same way the relations of the young of the same family
to each other precede consciousness and real individuality. The
132 CHILDHOOD OF ANIMALS

eggs are laid in a mass, in the same cocoon or in the same supply
of food, and the young grow up together necessarily tolerant of
each other’s presence. The swarm of caterpillars clustering on a
‘single branch, the globe of young spiders cohering round the remains
of the cocoon at first mean nothing except the accident of contiguity.
In most cases, aS soon as the individuals have reached a certain
degree of development or of size, they separate if they are vegetable-
feeding creatures, or begin to attack each other and so forcibly
separate if they are carnivorous. But the existence of cannibal
larve, even as rare exceptions, of instances where the first larva to
be developed devours its fellows, throws into stronger light one
striking result of the economic limitation of families and the
compulsory association of the young. It has created the necessity
for a modification of the predatory instincts of carnivorous crea-
tures and has led to the existence of a power of recognition and
selection. Certain things in the surrounding world they attack
and eat; other things are taboo, not to be attacked and not to
be eaten.

The most important result of the institution of family life
amongst invertebrates is the appearance of the social communities
of termites, bees, wasps and ants. The termites are the simplest
case. They form areal family, and all the individuals are potential
males and females. The workers and soldiers are at first not more
than young animals which have to pass a period of servitude in
the paternal home, ministering to the needs of the community,
before they go out into the world to lead their own lives. From
such a condition has come about the strange existence of individuals
so modified for their early duties that they cannot pass on to the
normal duties of normal individuals. In the social wasps and bees
there is the further complication that only females are selected to
do household work, and modified so that they lose the ordinary
selfish instincts and devote themselves entirely to the purposes of
the community, whilst the males develop only the instincts and
capacities of sex, and when they have served their purpose are
turned out to die. In the communities of ants, as in termites,
there are individuals modified to serve as workers and as soldiers,
but, as in wasps and bees, these are all arrested females, and the
males are used only for the purposes of sex. The colonies of ants
last a much longer time than those of bees and wasps, which
are annual, and this has given the possibility of a more intricate
LIMITATION OF FAMILIES 133

civilisation being developed and of much more complex instincts
being formed. When we think of the elaborate ordering of a com-
munity of ants, of the care devoted to the young, of the capture of
other ants and their use as slaves, of the domestication of aphides
and their use as milch cows, of the cultivation of fungi to be used
as foods, it is plain that there is nothing comparable until we reach
the highest organisations of civilised man. And yet these have
come about as a by-product of the formation of families.
CHAPTER IX

BROOD-CARE AND LIMITATION OF FAMILIES IN
LOWER VERTEBRATES

I HAVE already mentioned the prodigious fertility of many fish.
Most of the bony fish lay eggs in numbers that can be estimated
only in figures ranging from hundreds of thousands to millions.
Those in the ovary of a ling have been estimated at over twenty-
eight millions ; in a turbot of only seventeen pounds weight, nine
millions ; and in a cod of twenty-one pounds weight, six millions.
These eggs are extremely small and are discharged directly into the
water by the female, after which she takes no further notice of
them. They are known as pelagic—that is to say, whether they
are shed by fishes that spend their lives swimming either at the
surface or at no great depth, such as cod, whiting, hake and ling,
mackerel, pilchards or sprats, or by fishes which live on the mud or
sand of the bottom, they speedily rise to the surface and float in
the warmer water exposed to the light and heat of the sun. They
are transparent, almost invisible glassy spheres, each buoyed up
by a clear droplet of oil. At the usual spawning time, April or
May in northern waters, the whole surface of the sea is turbid with
the innumerable floating eggs and newly-hatched young, in the
favourite places for breeding, which are usually the rough waters
of bays, or near shoals on which the tides break. The eggs contain
very little food-yolk, and the tiny fish, as soon as they hatch, have
to begin feeding themselves. They are omnivorous, and find an
abundant prey in the still more innumerable young stages of various
crustaceans, molluscs and worms. The destruction is enormous;
the larger fishes devour the smaller; great flocks of sea-birds,
gulls, guillemots and gannets, scream and squabble as they gorge
on the larger fish ; whilst whales and dolphins come to join at the
feast. Other agencies share in the work of destruction ; a heavy
night-frost, a torrent of rain, or a storm of wind may destroy
millions.

Other kinds of fish descend to the bottom of the sea and lay

134
LIMITATION IN LOWER VERTEBRATES 135

submerged or demersal eggs. These are larger and are heavier than
sea-water. Herrings, although they swim near the surface, lay
demersal eggs, and a similar habit has been adopted by the wolf-
fish, gobies, suckers and many others. A certain amount of choice
is shown in the selection of the ground for depositing the eggs, and
these are usually enclosed in a firm and sticky capsule, or embedded
in lumps of mucus which enables them to adhere to seaweed or
stones. The numbers are much smaller, and are to be counted in
thousands, hundreds or dozens. The herring, which is the most
prolific of these fish with demersal eggs, deposits about twenty
thousand. Fishes, like salmon, which ascend rivers from the sea,
and most of the fresh-water fish, are also demersal, and many
of them show a certain amount of care in the deposition
of the eggs, scooping out holes and covering them with sand or
stones.

There is a heavy toll taken of unprotected demersal eggs, and
there are many remarkable instances in which brood-care goes
much beyond the mere choice of a locality for laying the eggs. The
spawn is often sedulously guarded by one of the parents, and it is
interesting that this duty is almost invariably assumed by the male.
The common British butter-fish (Pholis gunnellus) coils its body
round the mass of eggs, the male and female relieving one another
in this task, and then, after a time, hiding them in holes scooped in
the rocks by some of the boring molluscs. The female lump-sucker
attaches her eggs in sticky masses to rocks or logs and then takes
no further interest in them, but the male watches over them until
they hatch out, when the fry cling to his body by their suckers.
The sand-goby lays her eggs under the empty shell of a shellfish,
such as the scallop, and then the male watches over them until they
hatch. J.S. Budgett, who went to the Gambia to study the strange
African lung-fish, Protopterus, found that the eggs were laid in
circular nests hollowed in the mud on the edges of swamps. The
nest was an irregular hole about a foot deep, filled with water, but
unlined. It was surrounded by reeds, and these were crushed down
at one side, there being a sort of path by which the parent could
pass out and in across the little stretch of dried mud separating
the nest from the swamp. The female apparently deserted the
nest after laying the eggs, but the male stayed on, and was usually
found lashing his tail and keeping the water in violent commotion,
so that it was better aerated. The male guarded the young larve
savagely, biting at any one who tried to touch them. The young
136 CHILDHOOD OF ANIMALS |

larve grew suckers on their heads like those of tadpoles, with
which they fastened themselves to the sides of the nest. In the
same locality Budgett found the floating nests of Gymnarchus
niloticus, which were a foot and a half across and surrounded on
three sides with a rim of twisted weeds, the fourth side being
under the level of the water. The male kept a fierce watch over
the larve in the nest, snapping viciously at intruders. The
fantang (Heterotis niloticus) makes a nest four feet across with a
rim eight inches high, composed of the stems of grasses. In
making its nest the fish swims round and round, throwing its tail
upwards and outwards, and so tossing on the growing wall the
débris it removes from the central area. Soon after the larve
hatch they are taken out on trial swimming trips by the parent,
but return to their home. When they leave it finally, the parent
still keeps with them for a time. The bow-fin of the great lakes of
America leaves deep water in spring and moves to swampy shallows.
There they break up into little parties, each consisting of a female
and several males. The fish of one party construct a rude nest
by wriggling round and round in the mud until they clear a circular
area. In these the eggs are laid, and one of the males mounts
guard, the rest of the party dispersing. When the young finally
leave the nest, they are accompanied and protected by the guardian
parent for a time.

The American bullheads or horned pouts resort in pairs to the
muddy shallows at the edges of the fresh-water lakes they inhabit.
In water a few inches deep they gradually make a hollow in the
side of the bank, throwing out the mud and sand until a mound is
formed on the bottom with a shallow groove leading to the opening
into the nest. The excavation is done with the head, and although
both male and female share in the work, the latter is more zealous.
Sometimes the nests are made in the hollow, submerged stumps of
trees, sometimes scooped out amongst reeds and bulrushes. After
the eggs are laid, one or both parents remain to guard the young
larve, and then swim out with the shoals of little fish. Shoals
from different nests have been observed to join temporarily, but
afterwards to separate, so that it seems as if the corporate life had
led to a definite sense of recognition amongst the members of each
brood.

The nesting habits of the little sticklebacks which live in fresh,
brackish or salt water are well known. The male is the house-
builder, and uses weeds and twigs as his material, fastening them
LIMITATION IN LOWER VERTEBRATES 137

together with a sticky secretion from the kidneys. When the
female has deposited her eggs in the nest, she deserts it, and the
male continues to guard nest, eggs and young fry with the
most pugnacious spirit. The larger stickleback of salt water. has
similar habits, building a nest, in sheltered pools, of seaweeds and
plantlike colonies of hydroids. In
the brightly coloured marine wrasses,
both sexes join to build the nests,
which are constructed of broken shells,
seaweeds and other débris. The great
masses of gulf-weed forming the ‘‘ Sar-
gasso Sea’’ in the areas affected by
the Gulf Stream are a preserve for
marine creatures which drift about
in the protection of the weed. Amongst these,
the marbled angler (Antennarius marmoratus),
a small fish that rests on the weed with almost
armlike pectoral fins, constructs a globular nest
supported by silky fibres, within which the
eggs are suspended in bunches.

A few fishes reduce the number of the family
still further and protect it by carrying about
the eggs and young larve. The well-known
sea-horse (Hippocampus) (Fig. 28), which carries
itself erect when swimming and looks like the
knight of a chess board, has a pouch in the
male, on the front of the body opposite the
root of the tail, and in this the eggs and .
young larve are carried about. The pipefish, geo oo.
which is sometimes found amongst whitebait, pouch. (After Murray.)
has a similar pouch, which, however, is longer
and narrower, to suit the different shape of the body. In Soleno-
stomus, which inhabits the Pacific and Indian Oceans, there is a
similar pouch, but carried by the females, and formed of the ventral
fins. Most of the catfish protect their young by making nests and
guarding them with fury, more often the male, as Aristotle observed
in the case of the European catfish (Silurus glanis), but sometimes
the female, sometimes both sexes, performing this duty, and after-
wards herding the shoals of fry when they emerge. In a few cat-
fish the number of eggs is still further reduced, and the male or
the female, according to the species, carries them in the mouth and

  
 
138 CHILDHOOD OF ANIMALS

pharynx, a very singular case of the subordination of the normal
appetite to an unselfish duty. In the cichlids the same habit has
been developed, but most usually by the females. In Aspredo, a
large fish found in Guiana, there is a still more remarkable mode of
brood protection. The skin of the under surface of the body, over
the head, abdomen and paired fins becomes soft and spongy, and
the eggs adhere to this in a single layer; whilst the skin of the
mother forms cup-shaped receptacles richly supplied with blood-
vessels, and suggesting that the young embryos obtain nourishment
by a kind of placental connection. In the small fresh-water
bitterling of Europe, the female develops a very long tube at the
end of which is the orifice by which the eggs leave the body. She
uses this as an ovipositor, inserting it between the valves of the
shells of fresh-water mussels and discharging the eggs into the
branchial cavities of these animals, within which they go through
their development in security.

In nearly all the bony fish the eggs are fertilised after they have
left the body of the mother, and their subsequent development,
whether they are turned adrift or guarded in some of the curious
ways I have mentioned, is really independent of her. But in a
few instances not only is there internal fertilisation, but a large
part of the development takes place in the ovary of the mother,
and the young larve are fed not only by the small amount of yolk
deposited in the egg, but by a secretion from the walls of the
ovary which they swallow and digest. The blenny is the best-
known case of this device. The eggs are hatched in about twenty
days, but the young are not actually born until they are several
months old, by which time they are nearly two inches long and
are like the parents except in size.

In all Elasmobranch fishes, fertilisation is internal and the eggs
are very large and few in number. The breeding season extends
over the greater part of the year, and only one or two eggs are
ripened at a time. After it has been fertilised, the egg is enclosed
in a brown horny case, often oddly shaped, usually oblong or
quadrangular, with a hook or long tendril at each corner. In some
rays and the common English spotted dogfish these egg-cases are
deposited on the sea-bottom, or their tendrils are twisted round a
strand of seaweed. The secure position and the large and un-
palatable case protect the developing embryos for several months,
after which the young fish, now able to look after themselves, escape
through a slit in the egg-case. In most of the dogfishes, as, for
ogee

LIMITATION IN LOWER VERTEBRATES 139

instance, in the common smooth-hound, in many rays and in sharks,
the egg-case is very thin and delicate, the quantity of food-yolk in
the egg is much less, and the eggs are retained in the body of the
mother, lodged in special expansions of the oviducts, until the
embryos have hatched and grown to young fish. The walls of
these sacs form long filaments, supplied with blood from the vessels
of the mother and serving for the nutrition of the young. In some
cases this secretion is swallowed by the embryo in the same way as
in the viviparous blenny. In other cases, the nutritive filaments
of the mother are arranged in a pair of bundles, one of which is
thrust through each spiracle of the embryo into its alimentary
canal, where the nutritive secretion is taken up. There is a still
higher development of this mode of maternal nutrition of the
embryo in some of the sharks, which recalls the embryonic stages
of mammals. The blood-vessels of the embryo grow out over the
yolk-sac, and absorb the yolk and use it for the growth of the
embryo. When the yolk-sac is exhausted of its contents, the blood-
vessels covering it grow out into tufts which intertwine with similar
vascular tufts arising from the tissues of the mother, and through
such a placental connection the blood of the mother conveys
nutrition to the embryo.

Thus in various ways and by many different devices the number
in each brood of fishes becomes reduced in many species. Instead
of an enormous number being discharged to take their own chance,
a few are protected, sometimes fed, and only set free when they
have attained some degree of strength and capacity for protecting
themselves. As in lower animals, apart from its consequences in
better securing the maintenance of the species, this changed mode
of reproduction has a number of by-products. The growth of the
protected embryos, especially when they are supplied with much
food, either in the form of yolk or later on from the tissues of the
mother, is more direct and less a repetition of the ancestral history.
The instincts of the guardian parent or parents have become diverted
to new directions. Instead of being occupied throughout their
whole lives with their own individual concerns; the parents devote
some time and much trouble to matters which affect the safety of
the species rather than their own individual safety. They take
substances into the mouth, such as eggs, which would be good to
eat and yet do not eat them. They watch over, swim about with
and protect from others little moving creatures which a few weeks
before or a few weeks afterwards they would greedily devour.
I40 CHILDHOOD OF ANIMALS

The young, too, occupying the same nest, swimming in the same
shoal and following the same guardian, acquire some power or
habit of association which, if it were conscious, we should call
recognition.

Later on most fishes break away from the shoal and live strictly
individual lives, but there are not a few which continue to move
in masses throughout their lives, showing concerted action and a
feeble beginning of the social instinct.

Most of the tailless batrachians, the frogs and toads, and
many of the tailed batrachians, the newts and salamanders, lay
a very large number of eggs, and exercise the least possible dis-
crimination in their selection of a spawning-ground. The common
British grass frog (Rana temporaria) breeds very early in spring, and,
no doubt attracted by the relative warmth of the water, chooses
the shallow edges of ponds, or temporary pools which may dry up
in a few days and leave the spawn stranded. The natterjack toad
(Bufo calamita) lives in sandy places, heath land, maritime dunes
and so forth, and deposits its masses of spawn in the nearest water
it can find, being content with the temporary rainpools in cart-ruts.
These toads are common on many of the Surrey heaths near London,
where they may breed from April until July, and only a very small
proportion of the eggs laid succeed in developing. The common
toad (Bufo vulgaris) limits its breeding, at least in England, to a
few weeks, from the middle of March to the end of April, according
to the season, and moves great distances to particular favoured
places, generally deep pools in quarries, where it deposits its eggs
in much more favourable conditions. Nearly all the tailless
batrachians live in or near the water, and the eggs, which are very
numerous, are deposited in water with no special precautions. In
a few, such as the spotted salamander, the eggs are retained in the
body of the female until they have actually hatched or are on the
point of hatching; whilst some, such as Amphiuma and the
Ceecilians, lay their eggs on land and protect them by coiling their
bodies round them.

Amongst the tailless forms, however, brood-care may reach a
much higher level, with a consequent reduction in the number of
the young. Hyla faber, a Brazilian tree-frog, descends to the water
to breed, a male and female associating, but only the female pre-
paring the nursery for the young. She selects the shallow end of
a pool and dives to the bottom, bringing up loads of mud on her
head, which she gradually piles up to form the circular wall of a
LIMITATION IN LOWER VERTEBRATES 141

tiny pond, smoothing it with her hands on the inside and continuing
her labours until the edge is raised above the surface of the water.
The spawn is deposited in this little nest and the parents lurk near
it for some days, but appear to take no special precautions for
guarding the young. In other
cases the eggs are laid out
of the water, in holes or under
grass, so that they are saved
from aquatic enemies in their
early stages, and the tadpoles
are washed into the water by
rain after they have emerged
from the egg. Pholiamedusn %
theringi, a Brazilian frog, also
deposits her eggs out of water.
A male and female leave the
water together, climbing up
on flat leaves, one of which
the two animals hold twisted
to afunnel. The female de-
posits a mass of eggs in this,
and their sticky surface ad-
heres to’ the leaf, leaving it
folded round the mass. After
the formation of this simple
nest, there is no further pro-
vision for the young, and the
tadpoles, when they emerge,

N,

 

Fic. 29. Darwin’s Rhinodeyma, showing

have to wriggle down into Brood-pouch. The frog has been dis-
the water. The male of the sected from the ventral side ; the skin on

‘ : A the right has been cut away, showing the
midwife toad (Alytes obstetri- opening from the mouth to the pouch,
cans) a common batrachian the posterior half of which has been
7 - z 2 opened to show the young frogs. (After
in Europe, winds a string of Howes ; enlarged.)

eggs round his hind-legs, im-

mediately after they have been laid, and then retreats to a hole.
At night he comes out to feed, and at the same time moistens
the eggs, sometimes carrying them down to water and dipping
them in it. After three weeks of nursing them in this careful
way, the male carries them, now ready to hatch, down to the
water, where the tadpoles emerge, and his responsibility ends.
In Rhinoderma darwint (Fig. 29), a small frog discovered by Darwin
142 CHILDHOOD OF ANIMALS

in Chili, the male has a pair of sacs, normally used to increase the
volume of the voice, which open into the mouth on each side of
the tongue. In the breeding season the fertilised eggs, which are
only from five to fifteen in number, are placed in this, and as the
embryos develop, the sacs expand until they occupy the whole of
the lower surface of the body under the skin. Not only hatching
takes place in this secure retreat, but also the further development
of the young, which do not emerge until they are miniatures of the
adult. In Rhacophorus reticulatus, a Ceylonese tree-frog, there are
only about twenty eggs produced, and these after being laid are
attached to the under surface of the skin of the female, where they
are carried about in little pits, until the tadpoles hatch out. In the
Surinam toad, the male spreads the eggs, which are also few in
number, on the back of the female, where each sinks into a little
cup-shaped depression, afterwards covered by a lid, and are thus
carried about until the metamorphosis is completed. In Ayla
goeldii, a South American tree-frog, there are between twenty and
thirty large eggs, which are carried on the back of the mother,
supported by a flap or fold of the skin; and in the tree-frogs of the
genus Nototrema, which also live in South America, the females
have a well-developed pouch of the skin, placed on the back and
opening backwards, in which the eggs are carried until they are
either tadpoles or young frogs.

In all reptiles the number of the family has been greatly re-
duced, and not more than from six or seven to about one hundred
are produced at a time, except in some of the turtles and tortoises.
The eggs are large, containing enough food-yolk to nourish the
embryo until it is hatched in a condition closely resembling that
of the parent, except in size and pattern, but large and strong enough
to look after itself. In consequence of this, the old larval stages are
suppressed, and although the embryo passes through a phase when
it has gill slits and the appearance of an aquatic creature, this
takes place before hatching, and the young are terrestrial. Even
the aquatic reptiles come on land to breed, and there are no
more than vague reminiscences of their gill-breathing ancestors.
The eggs are enclosed in a firm shell, sometimes tough and leathery,
sometimes hard and brittle, but nearly always white in colour. In
most cases, the eggs are hatched outside the body, but in a few
snakes and liza-ds they are retained until the young are born, in
these cases the shells being very thin. Brood-care is almost com-
pletely confined to a choice of the place in which the eggs are to be
LIMITATION IN LOWER VERTEBRATES 143

laid, and the formation of a nest or burrow to contain them. The
females alone perform this duty, and although in certain cases the
mothers exercise some guardianship over the young after birth or
hatching, the males take no interest in them.

All the turtles and tortoises lay white eggs with a stout shell,
which may be thick and hard, or leathery. The females usually
make a hole in the ground, in some well-chosen locality, to which
they return year after year, and are at the pains to cover up the eggs
and so far as possible remove all trace of their presence—a necessary
precaution, as they are a favourite food of many different kinds of
animals. The female common European pond-tortoise selects a piece
of hard bare ground, which she moistens, and then bores a hole in
it with her tail, afterwards enlarging the cavity with her hind limbs
until it is several inches deep. The eggs are placed in this and then
the hole is filled up with earth and firmly stamped down so as to
leave no trace of the disturbance. The huge loggerhead turtle,
which lives in the warm seas of both hemispheres, comes ashore to
breed, and has been watched on the Florida coast. The female
scoops a hole in the sand, above tide mark, places the eggs in it, and,
having covered them over, returns to the sea and takes no further
notice of them. The young hatch out in six or eight weeks and at
once take to the water, selecting shallow rock pools. There is
great destruction of the young and of the eggs, and an unusually
large number of these is laid, sometimes as many as a thousand.
The green or edible turtle has similar habits, but is more careful
and lays as a maximum a hundred eggs. The females come from
great distances to well-chosen breeding-places on sheltered sandy
shores. They are shy and wary, looking for the presence of any
possible foes before they venture to land. Finally they proceed
just beyond tide-level, scoop out deep holes, lay the eggs, cover
them up and carefully smooth over the heap of sand that they have
dug out, to leave no traces of their operations, and are said to
return to the sea by a circuitous route, so that their nests cannot
be tracked out by the trail they leave on the beach. Box tortoises
lay asmall number of eggs and secrete them in soft ground or under
leaves so carefully that the young have very seldom been found.
The female of the common Greek tortoise, which is often kept asa
pet, lays from two to four eggs rather late in summer, and buries
them carefully in the ground. Soon after the young emerge they
bury themselves, and do not reappear until next spring. The
South American “ Arrau’’ turtle, the eggs of which are taken in
144 CHILDHOOD OF ANIMALS

great quantities chiefly because of the oil which is extracted from
them, has the curious habit of laying in communal nests. At the
breeding season, the females leave the water and go to sandy banks,
generally on islands in the rivers. A female excavates a hole about
three feet deep and lays over a hundred eggs in it, covering them up
with sand. A second and a third female then lay their eggs in
successive layers, covering them up, and so on until the hole is
filled. The female soft-shelled turtle of the Southern States of
North America leaves the water and selects a suitable bank, into
which she burrows, remaining for several days with only her snout
protruding. During this time she lays several dozen eggs, and
then crawls out carefully so as to leave them covered up.

In crocodiles and alligators brood-care is further advanced. The
eggs are large, oval and hard-shelled and are laid in a carefully
selected or prepared place, out of the water, and both the eggs
and the young are frequently savagely protected by the mother.
The Indian gharial digs a nest in the dry sand, arranging the eggs
in layers and carefully covering them. The Nilotic crocodile makes
a circular nest in the sand about two feet deep, with a raised floor
and undercut walls, so that the eggs when they are laid roll from
the centre under the protection of the wall. The first layer is
covered with sand and a second layer then added, and the whole
covered up. The mother remains on the nest to guard it, returning
to it after her visits to the water in search of food. When the
young are nearly ready to hatch, they make a barking noise inside
the shell; this is said to attract the attention of the mother and
to bring her back to the nest. She takes the young to the water
when they have hatched and guards them against their many
enemies for a considerable time. The female of the Mississippi
alligator makes a nest of leaves and soil a few feet high and deposits
several layers of eggs, afterwards covering them. She is said to
take no further notice of the young when they are hatched.

The young of all the alligators and crocodiles are hatched in a
lively and vigorous condition, and are able to snap rather savagely
almost before they leave the shell. I have personal experience
only of young alligators. These are very easily tamed, and quickly
learn to distinguish between persons, taking dislikes to individuals
and always snapping at them and refusing to be handled, whilst with
others they are gentle and docile. They make a loud barking noise
to attract attention. It is known that the mothers protect the
young in the case of some species of crocodiles, and I am inclined
LIMITATION IN LOWER VERTEBRATES 145

to think that this happens in most of the species. In any case the
newly hatched young remain together for a time, and tolerate each
other’s presence. Healthy crocodiles and alligators, young or old,
are rather savage creatures, when the water in which they are kept
is not so cold that they are torpid. They are ready to snap at any
moving object, or even at a piece of wood thrown into their
pool. And yet, although there are occasional accidents, they are
gregarious, seldom attacking one another savagely unless in an
actual struggle for food. Individuals of all sizes and of several
kinds may be kept safely together. This instinct of toleration for
their own kind is, no doubt, the result of the association of the
young with each other and with the mother. The voice is certainly
used as a recognition call. The strong musky odour, due to a
secretion from glands at the root of the tail, but which pervades the
whole body, may possibly also serve for recognition, but I have
never been able to detect the odour in young animals.

Lizards lay relatively large eggs, the numbers varying from two
to twenty or thirty. The process cf incubation takes a long time,
and when the young creatures emerge they are fully formed,
differing from their parents only in size and colour. They are
usually white, or very pale, and le quietly for a few days, and then
set about the business of life without any assistance or guardian-
ship from their parents. Little trouble is taken even about the
deposition of the eggs. They are usually placed in holes on the
ground, in heaps of leaves, or in any natural cavities. A certain
number are viviparous—that is to say, the eggs hatch just before
they are laid. The slow-worm, one of the common English lizards
(Lacerta vivipara), some of the chameleons and many of the skinks
are viviparous. Thus although brood-care among lizards is passive,
the large size of the eggs and still more the occasional viviparous
habit secure that the newly hatched or born creatures are mature
enough to be independent, and the number of the family has been
reduced.

The eggs of snakes are large, usually very elongated and en-
closed in a soft, but tough, shell. They are not very numerous,
varying from three or four to fifty. They are fertilised before they
leave the body of the mother, but the length of time they are
retained seems to vary a good deal even in individuals of the same
species, with the result that some eggs when they are laid contain
only the merest microscopic trace of the embryo, whilst in others
the young snakes may be almost ready to hatch. Snakes, in fact,

C.A. K
146 CHILDHOOD OF ANIMALS

seem to be on the way to protect the eggs by retaining them in
the body until they hatch, and many of them have actually become
viviparous. Amongst these are the smooth snake, the common
adder, most of the burrowing snakes and many of the sea snakes.
In viviparous eggs the shell is extremely thin. It is probably the
viviparous habit that has led to the belief that the adder opens her
mouth and receives her young into it when danger comes near.
Certainly the adder remains with and protects her young after they
are born, and the sudden disappearance of mother and young when
any one approaches is the starting-point of the notion. It has
been apparently confirmed by dissection, for if a gravid snake be
opened, her young, active and wriggling, may be found far forward
in the body, in a tube which is really part of the oviduct, but which
one not well acquainted with anatomy might easily take to belong
to the alimentary canal. The sea snakes are said to protect their
young after hatching, but maternal care in most snakes does not go
beyond finding a suitable locality for the eggs, which are usually
laid in heaps of earth and leaves, in holes, or in manure heaps.
The boas and pythons and some of the venomous snakes dispose
the coils of the body round the eggs and lie with them until hatching
takes place.

Thus in fishes, batrachians and the different kinds of reptiles,
there are to be found all stages in the process by which the number
of the family is reduced, and better protection given to the eggs,
larve and young. Prolificness is replaced by parental care, and
although there is little or nothing that can be thought of as educa-
tion, the instincts of both parents and young are modified by the
association in family life.
CHAPTER X
BROOD-CARE IN BIRDS

ALL birds lay eggs protected by a hard shell and containing a
quantity of yolk for the nutrition of the embryo. The greater part
of the development takes place after the egg has been laid, and is as
direct as possible, ancestral larval stages having been suppressed.
The eggs themselves and the young chicks are a tasty and nutritious
prey for many kinds of animals. Some lizards and many snakes
are eaters of eggs, whilst young birds are even more favourite
victims. These reptiles are keen-sighted, active and lively, and
hunt over the ground, searching the best-concealed crannies,
penetrating dense thickets and climbing the tallest trees. Nor do
birds themselves respect their own kind. In almost every family
there are some which will prey on the eggs and young of other
birds. Gulls, magpies, ravens, carrion crows, moorhens and brush
turkeys are notorious robbers, and will go long distances to ferret
out nests and young. Mammals of all kinds are even more serious
enemies, and not a few that are usually vegetarian often devour
eggs. Rodents, for instance, are habitually feeders on grain, roots,
leaves and other vegetable matter. But rats are clever and
persistent thieves of eggs, especially of those that are to be found on
the ground or in holes, whilst many will ascend bushes or tree
stumps in pursuit of their prey. Squirrels have a still greater
range of destructiveness, as they will hunt on the ground as well as
on the trees, and although for the greater part of the year they
are purely vegetarian, in spring they plunder nests. The Zoological
Society of London introduced American grey squirrels into Regent’s
Park, and although these have been a delight to the people of London
and have added greatly to the pleasure of visitors, it is probable
that they have seriously diminished the bird population. Wood-
pigeons, thrushes and blackbirds and all the small songsters that
build in shrubs and hedges have had their nests pulled to pieces
and their eggs and young destroyed. The smaller tree-climbing
carnivores, although many of them are vegetarian and frugivorous,
147
148 CHILDHOOD OF ANIMALS

cannot refrain from eggs, and the fierce and bloodthirsty stoats;
weasels and their allies are relentless persecutors of birds. Monkeys,
and man himself, are still more crafty and diligent in seeking out nests.
I do not know any monkey that will refuse an egg, and even the
great apes, which are amongst the most vegetarian of the Primates,
greedily devour eggs in all stages of incubation, as well as nestlings
and young birds. The civilised boy, birds’-nesting in the hedge-
rows, or scaling tall trees to add to his collection, is pursuing one of
the oldest habits of his ancestors.

It is almost a wonder that any eggs hatch into nestlings, any
nestlings survive to be fledged, or fledglings reach the relative safety
of adult life. And yet the eggs are so cunningly placed, and the
young so zealously guarded, that the limitation of the family has
reached much further than in the lower groups. The ostrich, it is
true, lays about thirty eggs, but this is an extreme instance. Birds
such as pheasants, partridges and other ground birds, which fly
badly and are specially exposed to the dangers affecting the young
of all birds, may lay as many as twenty eggs. Most of the smaller
arboreal birds lay not more than four or five eggs. Pigeons,
birds-of-prey and humming-birds usually lay two, and many sea-
birds such as petrels, divers and guillemots lay only one. So also
most birds breed only once a year, but, if the first brood be destroyed,
they may lay a second time.

Brood-care begins with the selection of a suitable place for the
deposition of the eggs. Occasionally degraded individuals, if we
take the ethical point of view, or unusually intelligent individuals,
if we take a view more consonant with human individualism, will
make use of the abandoned nest of other birds, or will turn out the
occupants of an inhabited nest, and use it for their own purposes,
and in some species this has become a habit. The cow-birds
or American starlings (Molobrus) are on the way to lose the nest-
building instinct which they once possessed. The Argentine
cow-bird has been seen by Mr. W. H. Hudson trying to build, but
failing in the effort. The females hang about the nests of other
birds, particularly the mud houses of oven-birds, and if they find
one that has been broken into, they lay their eggs in it. When
nesting-boxes were placed in trees, the cow-birds were the first
to visit them, inspecting them with mingled fear and curiosity,
but finally using them. Other cow-birds lay their eggs in the
occupied nests of other birds, and as their eggs develop very quickly,
the young hatch out before the legitimate occupants and rob them
BROOD-CARE IN BIRDS — 149

of the parental care which otherwise they would have enjoyed.
The common cuckoo and some other cuckoos carry this
parasitic habit further. The eggs are always deposited by the
female in the nests of other birds, and the young cuckoo, when
it is hatched, creeps under the nestlings of its foster-parents
and by a violent effort raises them one by one on its hollow back
and jerks them out of the nests, so securing undivided attention
in future.

Some birds are content with very little preparation for the eggs,
whilst in others the most elaborately constructed nests are prepared.
The New Zealand kakapo or ground-parrot hides in holes and burrows
and lays its eggs there without any preparation. Ostriches have
the reptilian habit of digging a hole in the ground, in making
which several females combine, and then deposit the eggs and
cover them up. Emus scrape a shallow hole in the ground
and do not cover the eggs. The cassowary scrapes together a
tude pile of leaves and mould on which she lays the eggs. The
apteryx lays a single enormous egg, which she hides among fern
roots. Most of the auks lay their single egg on a bare ledge of rock,
making no preparation for it. Penguins may lay on the bare rock
in the huge communal rookeries or breeding-grounds which they
frequent, or may scrape together a rude heap of débris. The
stone-curlew and the goat-sucker choose a site carefully, returning
to it year after year, but make no preparation, laying the egg on
the bare ground. Birds belonging to many different groups choose
natural cavities, burrows, caves, or hollow trees for their eggs, and
may either line these with leaves, feathers and other soft materials,
or make no further preparation. Not infrequently they use their
feet to enlarge the burrows, or even to dig them out. Puffins,
for instance, regularly breed in rabbits burrows, sometimes
turning out the rabbits, but enlarge them or make shift to
dig holes for themselves. Most of the petrels and a few ducks
breed in burrows. The stockdove and the rockdove breed in
caves, in clefts in the rock, or in holes in trees. Most of the
parrots, as well as kingfishers, hoopoos, owls and woodpeckers,
hornbills and sand-martins, dig out holes in wood or sand, or occupy
holes already made.

Most of the game-birds, shore-birds, waders, and ducks and
geese lay on the ground or in low-lying situations, and show every
transition from a mere scraping on the rocky shore to an elaborate
collection of twigs, leaves, plant refuse of all kinds, making heaps
150 CHILDHOOD OF ANIMALS

which may be several feet high, whilst some, like the redshank,
build a dome of grass over the eggs. Floating nests on rafts of
water-weeds or sticks are not uncommon, and there may be little
attempt at choice of situation, or the greatest care may be taken
in selecting a naturally concealed spot. Some of the mega-
podes or brush turkeys bury their eggs in the sand, and take
no further trouble, leaving incubation to the chance warmth
of the sun. Others build enormous heaps of decaying leaves,
the natural fermentation of which forms a hotbed in which
incubation takes place, without assistance from the body-heat of
the parents.

Although owls select holes in trees or in caves, and line them with
some warm material, the diurnal birds-of-prey select open ledges,
generally on inaccessible cliffs, and there construct a very simple
nest of coarsely entangled material. Twigs and dry branches are
collected and roughly intertwined, and may form a great pile con-
taining many hundredweight of materials. The nest of pigeons
is a platform of twigs so slight that the eggs are visible from below.
Crows and herons build nests which show little more skill. The
magpie starts with a similar rude platform, but may surround it
with a hedge of thorns, or roof it over with a dome of twigs. A pair
of hammerkops or tufted umbres living in the London Zoological
Gardens constructed a nest which is a further advance on that of
the magpie. They made a platform of sticks, cemented with mud,
and covered it with a huge dome of sticks nearly two feet in height,
leaving a small entrance at the side. Some of the finches, as, for
instance, the hawfinch, begin with a platform and then place on it
a cup woven of hair and rootlets. Thrushes make a cup of rootlets
and wool and twigs, supported on a platform of twigs, and then
line it with a plaster of mud and cow dung. In the more elaborate
nests of many of the small singing birds, the use of mud as a cement
is discarded and the whole nest is woven of the finest hairs, vegetable
fibres and wool, softened during the process of building by saliva
from the mouths of the builders. The most curious and elaborate
shapes may be attained, pendulous purses, globes or retorts, or
hanging baskets. There may be one or more entrances, and these
may be prolonged to form tubes or twisted tunnels, possibly to
make access by snakes more difficult. The tailor birds select large
pendulous leaves and with their beaks pierce rows of holes
along the two edges of the leaf, and then first twist a thread out
of spiders’ webs, fragments of wool or cotton, and, weaving it in and
BROOD-CARE IN BIRDS I5I

out of the holes they have made, bring the edges of the leaf together,
transforming it to a hanging purse, within which the nest is built.
The ingenuity and diversity of the various woven nests are endless,
and allied species show all the stages between rude structures and
exquisitely finished houses. There are so many instances of different
formations of the nest according to the difterent environment in
which the birds live, and so many cases where it seems plain that
the instinct is partly degenerate, that it is impossible to arrange a
parallel series between the complexity of the nest and the position
of a particular species in its family. Types of construction run
through the nests of allied species, but appear in all stages of per-
fection and degeneration.

Just as it is impossible to draw a sharp line between birds which
lay on the ground or in holes, using no soft nesting material, or
little or much of it, so there are many transitions between nests built
chiefly of fibrous materials, animal or vegetable, partly cemented,
or lined or mixed with mud and saliva, and nests which are formed
of mud or saliva almost wholly. As, however, many of the nests of
plastic material conform with shapes naturally suggested by fibrous
substances, it is more than probable that sticks, twigs and wool were
used and then discarded. So also in the pursuits of man, rude
basket-work preceded pottery. Early human workers found that
they could improve their baskets by daubing them with clay, and
then some made the great discovery that clay alone was necessary.
Early pottery, however, is often ornamented with patterns that
suggest its primitive origin from smeared fibres. Similarly there
are transitions between mud nests and nests in holes. The hornbill
selects a hollow tree, but the male shuts in his mate with a wall of
mud. A North American cliff-swallow selects a hole, but builds a
rim of mud round the aperture. Swallows build their familiar
dwellings, in corners under the eaves of houses, of pellets of earth
which they collect and moisten, but mix with fragments of hay.
The Australian grey struthidea makes a circular nest with vertical
walls wholly of mud, supporting it on the branch of a tree.
Flamingoes build very large conical mounds of mud, in the swamps
by the sea, and hollow a space on the summit for the reception of
the eggs. Several individuals, probably a male with two or three
hens, of the South American oven-bird combine to build a very large
oven-shaped structure. They choose the branch ofa tree or the top
of a post and carry to it innumerable little pellets which they make
by kneading horsehair or rootlets with mud ina pool. They first
152 CHILDHOOD OF ANIMALS

construct a platform nearly a foot in diameter and then gradually,
layer by layer, rear up a circular wall curving inwards until it
becomes a closed dome with an aperture at one side. The aperture
leads into an outer chamber, and there is a second inner chamber
placed high up and lined with soft material for the reception of the
eggs. Some of the swifts in Indo-Malay and Australia make
saucer-shaped cradles of thick saliva mixed with feathers and
fibres, while the swift from nests of which “ birds’-nest soup ”’ is
made uses only saliva.

When the ‘‘nest ” is merely a hole scraped in the ground, in most
cases it is the work of the female only. When it consists of a
quantity of material scraped up, or collected from a distance, or
woven or moulded into a specially shaped receptacle, both males
and females join in the task. There are a good many cases where
birds associate in colonies for nesting. We are all familiar with
rookeries, and with the massed nests of swallows and swifts. A
great many sea-birds lay their eggs or construct their simple nests
so close to each other that they almost touch, and there are one
or two instances where birds combine to form enormous structures
containing the individual nests of many pairs. It is probably
more the common choice of a suitable site than any social instinct
that has led to these associations. Although quarrels and robberies
are frequent, there is a certain amount of combination against
common enemies, but the families remain really distinct, and there
is nothing approaching the ordered communities that occur
amongst insects.

When the receptacles are ready, the females place the eggs in
them. Eggs differ remarkably in shape. Some are almost spherical,
most are elongated ovoids with one end larger than the other, in
the extreme cases the eggs being pear-shaped. Rounded and
regularly ovoid eggs, if given a push on a smooth surface, will roll
a great distance ; pear-shaped eggs simply twist round in a circle
of which the narrow end is the centre. Such eggs would certainly
be little liable to breakage by being rolled off rocky ledges, and they
are found in the case of many birds which lay in dangerous
situations, but they also occur in shore-birds where there is no
similar danger. There appears to be no advantage or special
adaptation in the various gradations from nearly spherical to
oblong eggs.

The shell of eggs is a transparent, organic membrane thickened
and hardened with deposits of lime, and the natural colour,
BROOD-CARE IN BIRDS 153

perhaps the primitive colour, is white as in the case of
reptiles. In a very large number of birds belonging to different
groups and with different habits the white colour is retained.
Perhaps the most common case is that of birds which lay in holes
or in covered nests, and it has been suggested that it is an advantage
in such circumstances, for white is more visible in dim light, and
therefore possibly a bird entering its dark nesting-place might see
its eggs more easily if they were white. I cannot believe, however,
that birds are so stupid as to run any great danger of missing their
own eggs. The fancy of museum naturalists has even led them to
suppose that a bird like the English puffin, which has a coloured
egg overlain by a white chalky encrustation, has only recently come
to occupy burrows in the nesting season, and so has contrived to
cover up the colour of its eggs. Cormorants, however, nest on the
open ground and similarly have eggs the pale blue or green colour
of which is concealed by a coating of chalky white, and Guira
cuckoos, which build open nests, have pale blue eggs partly covered
with a network of chalk. Another explanation perhaps errs in
attributing too much intelligent reasoning to the’ birds. This
is that many birds whose eggs happen to be white take them
to holes to hide them.

We are on safer ground if we simply remember that if the eggs
of birds were originally white, there can at least have been no
disadvantage in that colour being retained by those which are laid
in holes and other dark places. The ostrich buries its white eggs in
the sand. Barbets, bee-eaters, hornbills, jacamars, kingfishers,
motmots, owls, parrots, a few pigeons, rollers, todies, toucans,
trogons and woodpeckers all lay their white eggs in holes in the
ground or in the hollow branches of trees. But curassows, frigate-
birds, frogmouths, most herons and bitterns, many of the smaller
birds-of-prey, colies, pelicans, most pigeons and storks make open
platforms or nests visible from above and yet still lay white eggs.
The apteryx has white eggs laid on the ground, roughly concealed
under foliage. The larger birds-of-prey have white eggs or eggs
blotched with red and lay them in the open. The eggs of ducks,
geese, swans and flamingoes are glossy white, or at the most have a
pale tint of yellow or blue ; many of the game-birds have eggs that
are nearly white, those of grebes are white, although later on they
become stained from the wet moss and reeds of the nest, pelicans
have white eggs, penguins have eggs that are white or nearly white,
screamers have white eggs, trumpeters have white eggs, and all
154 CHILDHOOD OF ANIMALS

these lay their eggs either actually on the ground or on low and
visible nests.

The relation of coloured eggs to the environment is even more
difficult to interpret as an intelligible adjustment of condition to
environment. The colours of eggs are all due to pigments which
are derived from the blood and find their way to the outer surface
of the eggshell through the walls of the oviduct. If a bird with
an egg nearly ready to lay is frightened so that it rids itself of its
burden before the normal time, the premature egg is frequently
paler, or even colourless, and if more than one egg is laid, it frequently
happens that those which are deposited first are less brightly marked
or coloured than their successors. Many birds lay eggs which are
very different in appearance from each other. Guillemots and
cuckoos are well-known instances of this, and attempts, in my
opinion quite unsatisfactory, have been made to show that the
cuckoo chooses nests with eggs corresponding in colour to those
which she has laid, as the repositories for her own produce. Many
of the birds-of-prey, the secretary bird and some petrels, lay white
or very pale eggs with irregular blotches or spots of red, the latter
in holes, the former on rude heaps of twigs in the open. The South
American ostrich or rhea buries her eggs like her African relative,
but they are green or yellow at first and afterwards fade to a dirty
white. The cassowary and the emu deposit on open nests eggs
which are evenly coloured with bright or dark green. Tinamous
lay, on the bare ground, highly polished and lustrous eggs, self-
coloured with vivid shades which differ remarkably in the different
species, chocolate, purple, blue, blue-green or primrose. Turacos
lay green eggs on an open platform, the hoopoos green
eggs in holes, and the bustards greenish eggs with reddish
blotches in rude nests on the ground. Some ibises and spoonbills
lay blue eggs in nests on trees. There is rather more uniformity
in the case of spotted and blotched eggs, which in many cases are
laid on the open ground and may gain some protection from their
resemblance with pebbles, a protection which is most efficient in
shore-birds. The latter, most of the gulls, coursers, nightjars,
cranes and button-quails lay spotted or blotched eggs on the ground,
often with the merest scrape in the sand to serve as preparation.
Similar eggs are laid by auks in holes or on ledges, by cariamas on
the ground, in bushes or on trees, by divers on masses of grass and
herbage piled up near the edge of the water, by sun-bitterns on a
platform, and by hoatzins on tall trees. Finally, amongst passerine
BROOD-CARE IN BIRDS 155

birds almost every kind of egg, white, evenly tinted with some
bright colour, spotted or blotched, is to be found, and he would be
ingenious indeed who could arrange them in a system coherent
with their environment.

The explanation of the whiteness of white eggs as an adaptation
to the kind of places in which such eggs are laid requires a great deal
of bolstering up and stretching to make it fit the facts. So also the
theories of similar adaptations in the case of coloured eggs require
still more special pleading. Certainly many of the blotched eggs
which are laid on rocky ground or left uncovered amidst low herbage
fit their surroundings extremely well, and may be protected by
their invisibility. But there are other spotted and blotched
eggs which are laid in holes or on inaccessible ledges, or in covered
nests, and the explanation of protective resemblance is far from
complete. It seems almost impossible to imagine that there is
any protective advantage in the brilliantly coloured eggs, those
with purple or green or light blue or burnished red hues, and to
add to the difficulty these are laid in all sorts of situations, on the
ground, in holes, or in covered or uncovered nests. The ingenious
suggestion has been made that the original egg-eaters from snakes
to monkeys became accustomed first to white eggs, as primitive
eggs were all white, and that later on the bright colours puzzled
them, and made them fail to recognise that such gaudy objects were
edible. Hungry animals, however, are so experimental, so disposed
to try the taste of every strange object that comes before them, that
I do not think this suggestion carries us very far. If it were the
case that brightly coloured eggs were often addled, or had nasty
tastes, as happens with many brightly coloured insects, one might
believe that egg-eaters after a few experiments would give them up.
But as any daring animal that refused to be put off by colour, or
any animal with no natural appreciation of colour, would at once
discover that the colour was only shell-deep and that the contents
were excellent, protection would soon come to an end.

We have to remember, however, that the existing colours and
patterns of eggs and of animals may be survivals from circumstances
in which they were useful. Animals, even in recent times, have
spread from one country to another, have been driven or have
migrated from the hills to the plains, from the jungle and forest to
barren, open country. They have changed their habits from choice
or from necessity. Birds of the same species often nest under
different circumstances in very different places, sometimes in holes,
156 CHILDHOOD OF ANIMALS

sometimes on the ground and sometimes on trees. Closely allied
species in many cases show great differences in their choice of
nesting-places and in the nature of the preparation they make.
Habits and surroundings may thus change very quickly, much more
quickly than we can suppose structure and function to change,
and colours and patterns that had fitted a former environment
may seem strange and unsuitable in a new environment. No doubt,
if they were very unsuitable, the old colours and patterns might
lead to the extermination of their owners, before they could be
changed. But equally possibly the advantages of the new habit
or new surroundings might be so great that they would counter-
balance the garb that had lost its suitability. Birds are a highly
successful branch of the animal kingdom, with great powers of
locomotion and with great capacities for adapting themselves to
new circumstances, and we might well expect to find amongst
them many cases where coloration had outlived the conditions
to which it was suited.

I hesitate, therefore, to throw overboard the conception that
the coloration of the eggs of birds is adaptive. In many cases it
is extremely suitable, and there may be other cases where it was
recently suitable. I prefer to see in it, however, another instance
of the change from the plain to the coloured, from the dull to the
gay. It isa process not designed for the pleasure of man, although
in many cases it delights his eye. It is a process which, so far
from necessarily being of advantage to the animals in which it
appears, sometimes adds to their cares, but which is occasionally
neutral and now and again of benefit. Eggs were at first white,
but there isa tendency for them to be stained with the bright exuda-
tions of the body, with the by-products of the vital chemistry of
the blood. Natural selection, so to say, has hung on the outskirts
of the process of change, and has retarded it where its results were
dangerous, and has encouraged it where they were useful, and
where they were indifferent it has left matters to their natural
course.

When the eggs have been laid, they have to be kept warm until
they hatch, a duty that is avoided only in a few rare cases. Birds
are even more hot-blooded than mammals ; it is not always easy to
take their temperature accurately, as the act of handling them
excites them and raises the temperature, but it seems to range
from the human normal to about 104° or 105° Fahr. The eggs
must be kept at temperatures approaching or surpassing these
BROOD-CARE IN BIRDS 157

for the whole period of incubation, although cooling for a short
time, such as happens when the brooding bird leaves the nest to
feed, does no harm, and is even imitated by those who are most
successful in using artificial incubators. The time required varies
from about ten days (in some of the small singing birds) to about
six weeks or two months (ostrich). On the whole it is rather
shorter in small birds than in large birds, at least within the same
families. Thus the small ducks require about three weeks, geese
about a month and swans about forty days. Comparing groups
with groups, there is much difference which is not easy to explain,
but the most general arrangement is that when the eggs are small,
containing little food-yolk, and the young are hatched in an im-
perfect condition, the period of incubation is short, as, for instance,
amongst passerine birds, and where the eggs are relatively large,
containing much food-yolk, and the young are hatched in a more
advanced state of development, the period occupied is longer.

All the megapodes or brush turkeys have given up brooding the
eggs. Some of them lay in the warm sand, others are said to select
the neighbourhood of hot springs, whilst others again, like the
brush turkey most familiar in captivity, make huge mounds of
vegetable matter, the fermentation of which supplies the necessary
heat. The cuckoosin the Old World, and the cow-birds in the New
World, foist their eggs on other birds for incubation as well as for
subsequent feeding, and not a few of the owls are suspected of the
same habit. .

In some cases the male bird performs the whole duty of incubation.
This happens in the cassowary, rhea, tinamous, phalaropes and
painted snipe, and it is amongst these that the curious cases occur
in which the males are more dully coloured than the females. In
many birds both sexes share the duty. The cock ostrich watches
over the hole in which the eggs have been buried, by night, whilst
the hen takes up the duty by day. The screamers work in shifts
of two or three hours each. When they bred in the London
Zoological Gardens, it was noticed that the cock bird acted as time-
keeper, and at the end of a watch used to come and push the female
off the nest. The emperor and king penguins lay their single eggs
on the bare ground, often in extremely inclement weather when
there are heavy storms of snow and severe frost. Each egg is
brooded on the flat feet of the bird, and a warm flap of skin and
feathers, specially enlarged during the breeding season, hangs.
down from the abdomen and covers it like a blanket. From time
158 CHILDHOOD OF ANIMALS

to time the male and female relieve one another, and this is done
with a quaint ceremony of bowing, and with a careful scrutiny of
the egg before it is handed over. Large numbers of eggs are
destroyed by the weather, and so great is the desire of these birds
to brood that they will steal an egg for this purpose. Probably the
eggs are changed so often that family rearing has been replaced by
communism. In the sand-grouse and the bustards both parents
share in incubation, but in the great majority of the higher types
the female alone does the work.

When the female only broods over the eggs, the male may take
no interest in the proceedings, or may remain as a guardian of the
nest and hen, or may assiduously feed her. As soon as the female
duck begins to sit, the drake flies off and does not reappear until
the young are nearly fledged. In gulls, most of the birds-of-prey,
swans, storks and rails the male keeps near the nest, and savagely
attacks any intruders. In Montagu’s harrier and some other birds-
of-prey, the cock brings food to the hen, whilst it is almost the rule
amongst singing birds for the male to remain with the female and
assist in feeding her. The hornbill, which walls up the female in
the trunk of a tree during the breeding season, feeds her most
diligently, and indeed she would otherwise starve.

All birds during incubation take a great deal of trouble with the
eggs, often turning and rearranging them, sometimes covering them
up when they leave them, and often bringing fresh material to add
to the nest. It is quite certain that sometimes because they have
been disturbed, possibly when some of the eggs have been taken,
and sometimes for no apparent reason, they get dissatisfied with
the nest, become suspicious and desert it. If a nest be disturbed
before its construction is completed, the birds generally leave
it and begin a new one somewhere near. In zoological gardens,
building birds are very capricious in this matter and will frequently
pull a nest to pieces and begin a new one, or desert the old one
entirely. When the eggs have been laid, what usually happens,
if a disturbance has taken place, is that the nest is deserted, and if
it is sufficiently early in the season, a new set of eggs is laid in the
new nest. Even when the young have been hatched, desertion is
the usual result when the parent has been disturbed or annoyed.
In similar cases amongst mammals, the mothers, even although
they are not naturally carnivorous, will kill and eat their own
young.

Brood-care of another kind begins when the eggs hatch out, and
BROOD-CARE IN BIRDS 159

its nature depends partly on the condition of the young chicks.
There can be no doubt but that birds are modified reptiles, and
most probably ancestral birds, like living reptiles, hatched out in a
condition in which they were active and very closely resembled
their parents. If they were unable actually to fly, they at least
could run about actively, and make fluttering or gliding and para-
chute-like motions with their wings. The megapodes are the only
living birds that are hatched in such a stage that they are able to
fly at once, and in which parental care ceases with the laying of the
eggs in a suitable place. It is improbable, however, that these
represent an actually primitive condition that has survived.
They pass through a moult before they are hatched and it is very
likely that their extreme precocity is a comparatively recent
acquisition. If we count, not by species, but by orders, sub-orders
and really well-separated families, then by far the greatest number
of different kinds of birds are hatched in a stage in which, although
they are not able to fly, they are alert, active, able to see and to
pick up their own food, and all these are clad from the first in a coat
of down. Lists of names are not usually interesting, but I am
going to give a rough list which, although not complete, will carry
conviction, The young of the following groups are active and
downy, or precocious when they are hatched: Auks, bustards,
cariamas, cassowaries, coursers, cranes, curassows, divers, ducks,
geese and swans, emus, flamingoes, frigate-birds, frog-mouths,
game-birds (including pheasants and fowls, peacocks, partridges,
quail and all their allies), grebes, gulls, hemipodes, hoatzins, jaca-
mars, kiwis, nightjars, ostriches, penguins (although these are
rather helpless), rails, rheas, sand-grouse, screamers, seedsnipes,
sheathbills, shore-birds, (including all the plovers, turnstones,
woodcock, snipe, avocets, oyster-catchers, sand-pipers, and their
immediate allies), tinamous, turacos and trumpeters. This list
plainly includes birds of very different types with very different
habits, but I think I can make the general statement about it that
it does not include the higher types of birds and notably the perching
and singing birds.

Next, there is a smaller assemblage of birds, to which the penguins
in the first list form a halfway stage. In these the young are
helpless when they are hatched, but are covered with a coat of
down. Such are the American vultures, all the ordinary birds-of-
prey, the eagles, hawks, harriers and Old World vultures, herons and
bitterns (although in the latter the coat of down is thin and hairy),
160 CHILDHOOD OF ANIMALS

ibises and spoonbills, lyre-birds, owls, petrels, pigeons (in these
again the down is so scanty as almost to be absent), the secretary
bird, storks, sun-bitterns and tropic birds. Most of these are
rather large or powerful and ferocious birds, well able to defend
their young. Lastly there is a group in which the young are
hatched naked and helpless. The pigeons and herons almost
might be placed here, and the group includes some like gannets,
cormorants, and pelicans and parrots, in which down is very soon
developed, and many in which there are slight traces of down, but
on the whole they are practically downless. This third list contains
barbets, bee-eaters, cormorants and gannets, cuckoos, honey-guides,
hoopoos, hornbills, humming-birds, kingfishers, motmots, colies,
parrots, passerine birds, pelicans, rollers, swifts, todies, toucans,
trogons, woodpeckers. The most general statement to be made
about this last list is that it contains those birds which most
anatomists would recognise as being the highest or most bird-like
birds.

There has taken place amongst birds, or rather I might say there
is taking place amongst birds, a change from a condition in which
the newly hatched young can very quickly look after themselves,
to a condition in which the young are absolutely dependent on their
parents for some time after they are hatched. The older, more
reptilian condition in which the young were provided for by a
merely material sacrifice on the part of the mother, by storing a
large quantity of yolk in the egg, is being replaced by a condition
in which the self-seeking instincts of the parents are temporarily
changed into instincts and habits where the main object of life is
not self-interest, but the satisfying of the needs of others.

Even when the newly hatched young are fairly active and soon
able to feed themselves, one or both parents guard and protect
them for a considerable time. They exchange call-notes and when
danger comes near, the young hasten to shelter under the wings
of their parent or squat down whilst she attempts to lure away the
intruder, sometimes, like the plover or the partridge, pretending to
have a broken limb or to be lame, and so diverting attention to her-
self, sometimes, as in the case of the hens of fowls and pheasants, or
by the cocks and hens in gulls, attacking the supposed enemy savagely.
A few birds carry their young about. The woodcock holds them
between her legs, partly supporting them by her beak when she
flies from one feeding-ground to another. Grebes carry the young
on the back as they swim through the water, and every one must
BROOD-CARE IN BIRDS 161

have seen cygnets taking refuge on the back of the male or female
swan, nestling under their wings as they swim (see Plate XI, p. 240).

When the young are helpless, the parental care and protection
are even greater. Birds which are naturally timid will fly out and
strike savagely at disturbers of their nests and young, whilst those
that are strong and predatory are extremely dangerous to approach,
when they are with eggs and young. Most of them take great trouble
with the sanitation of the nest or of the breeding-hole, first them-
selves carrying away the droppings of the young birds, and after-
wards encouraging the nestlings to void their excretions over the
edge of the nest. There are a few birds, such as hoopoos and
kingfishers, which take no trouble in these matters, but the nests and
the bodies of most young birds are kept scrupulously clean.

Finally, in all cases where the young are helpless, and in a good
many where they are active, one or both parents work assiduously
in feeding them. Whatever be the natural diet of the adults, the
food of the young is almost always animal matter. There are of
course some exceptions. Ostriches, almost as soon as they are
hatched, begin to crop green herbage for themselves, although
cassowaries, emus and rheas require food such as insects and spiders.
The secret of rearing ducklings of almost every kind is to supply
them abundantly with the common duckweed of ponds, and although
there is usually a rich microscopic animal life adherent to these
plants, the bulk of the food is vegetable. But all the soft-billed
birds, which are naturally insectivorous, most of the fruit-eaters
and practically all the hard-billed seed-eaters work from dawn to
dark searching for grubs, caterpillars, maggots, worms and all
manner of creeping and flying things to feed their hungry young.
Other birds hawk insects on the wing for the same purpose, and those
who resent the occasional devastations of their fruit-gardens and
seed-beds should remember that human life would be almost in-
tolerable, and the to.l of the gardener and farmer almost futile,
were it not for the destruction of insects and their larve which is
the work of birds engaged in feeding their young.

Many birds feed their young on food which they have partly
digested and throw up. Some of the finches, which at first bring
insects to their young, afterwards feed them on partly digested
food. Parrots also digest their vegetable food and supply it to the
young in this condition, whilst some woodpeckers, martins and
others throw up digested insects. Storks break up frogs, worms,
pieces of fish or flesh, mix it with partly digested matter and throw it

C.A. L
162 CHILDHOOD OF ANIMALS

on the edge of the nest for their young. The adult gull on Plate VIII
was drawn in the attitude assumed just before she throws up food
for the young. Petrels secrete a kind of oil from the fish on which
they live, and discharge it by their beaks into the mouths of their
young. Little cormorants thrust their bills down the short straight
throat of their mothers and help themselves from her stomach;
whilst young pel cans take fish from the mother’s enormous pouch-
like bill. Young pigeons obtain their food by thrusting their
beaks into the mouth of the mother and absorbing the so-called
pigeons’ milk, which is partly digested food and partly a secretion
from the crop. Whatever method be adopted, the feeding of the
young may go on until these are nearly as large as the parents.

Young birds, especially those that are born naked, are extremely
sensitive to cold, their temperature rising and falling with that of
the surrounding air, just as happens with reptiles, and no small
part of the duty of the parents is to keep them warm. This is
generally the work of the mother, and for some days, in the case of
the smaller singing birds, she hardly leaves the nest, the male
during this time doing all the work of foraging. In four or five
days the little birds have found their feet and are able to move
about in the nest, and then the mother is able to leave them for a
longer interval, and to take up her share of collecting food.

And so in nearly all birds, from the choice of the place for the
eggs, through the long duty of incubation, and for a longer or shorter
period after the young are hatched, one or both of the parents
are fully occupied with parental duties. The final period of brood-
care lasts for periods varying from three weeks to several months.
Then suddenly it comes to an end. The parents resume their
natural devotion to their own personal wants, and even those that
have been most assiduous and most devoted now quite suddenly
either fly off to new haunts, leaving their offspring behind, or drive
the fledglings away from them. The abandoned young often
consort until they have reached sexual maturity, when new instincts
awaken and the battles for mates begin.

If the time occupied in building the nest, in incubation and in
looking after the young be added, and if it be remembered that
most birds breed at least once a year, and those which get over
their duties quickly often breed twice a year, we reach the conclusion
that a large part of the time of adult birds is occupied with parental
care. This increased care has made it possible for the number in
the family to be very greatly diminished.
PLATE VIII
SEA-GULLS AND YOUNG

In the foreground are newly hatched young gulls in spotted
downy plumage. Above them, and in the attitude assumed
‘just before throwing up food for the young, is a great Black-
backed Gull in the full black-and-white plumage of the
adult. Above that is a gull in the plumage before the
‘final stage ; there are still spots on the head and much
brown on the wings. The bird highest up on the plate
is in an early immature plumage, still completely spotted
and mottled.
 

 

3

 

 

 
CHAPTER XI
BROOD-CARE AMONG MAMMALS

MamMALS are not only the highest group of the animal kingdom,
but one of the latest products of evolution. At a time which is not
very remote in geological history, a set of reptiles slowly assumed
the mammalian characters, and there is no reason to doubt but that
these ancestral reptilian-mammals laid large eggs like living reptiles.
Some of the living reptiles, like some living fishes, retain the eggs
in the body until they are almost ready to hatch, and so secure
for them warmth and protection much more certainly than in
the most cunningly devised nest. Some reptiles even keep the
eggsin the body until they hatch. It is most easy to understand
what now happens in mammals if we suppose that their reptilian
ancestors had acquired this habit of egg retention. The lowest
living mammals, the duck-billed mole and the spiny anteater of
Australia, still lay rather large eggs, but retain them in the body until
they are nearly ready to hatch. The marsupials and all the higher
mammals not only retain the eggs in the body but change the way of
feeding the embryo in a fashion that is foreshadowed even in some
fishes. In ordinary large eggs which contain enough food stored up
as yolk to nourish the young until it is hatched, the blood-vessels
of the growing embryo spread out over the yolk just under the
eggshell and absorb oxygen from the air through the shell as well
as food from the yolk inside the shell. When such an egg lies in
contact with the wall of the egg-duct of the mother, the supply
of oxygen for the embryo must be picked up from the blood of the
mother. This hasled totwo changes. In the first place, the embryo
picks up from the blood of the mother not only oxygen but the food
it requires, so that the yolk is no longer necessary ; and in the second
place the eggshell becomes thin, soft and membranous so that the
connection between the blood of the mother and of the embryo
becomes closer. Most of the marsupials have remained in this stage.
They have eggs that are smaller in proportion than those of reptiles

or than those of the lowest mammals, but much larger and containing
163
164 CHILDHOOD OF ANIMALS

more food than those of the higher mammals. In the latter there is
practically no food-yolk at all, and the eggs are microscopic in size,
being just visible to the nakedeye. They soon develop a connection
with the maternal tissues which is a legacy from the blood-vessels
which spread out under the shell, and then replace that by a
new and more perfect means of drawing nutriment from the blood
of the mother, the structure which is known as the placenta.

In mammals, therefore, the earliest stages of brood-care, instead
of being apparently conscious, external acts, which, so to say, might
be slurred over, bungled or forgotten, have become a part of the un-
conscious mechanism of the body. Instead of having to construct a
safe place in which to lay eggs, the mother retains them in the interior
of her body, supplies them with the necessary warmth and food, and
protects them from enemies at the peril of her own life. This change
from external to internal protection is least complete in the egg-
laying mammals, more complete in the kangaroos (where the young
are born when they are very small and placed in an external pouch
by the mother), and most complete in the higher mammals. Just
as there are some birds hatched when they are ready to run about
and others hatched when they are still blind and feeble, so there are
some mammals where the young are born almost ready to walk or
to run, and others where they are born blind and naked, differences
which depend on the habits of the animals and may be found amongst
species that are very closely allied.

This internal organic brood-care is just as effective in protecting
the young as the brooding of birds, and it is followed by a still
longer period in which the new-born mammals are fed and guarded
by the mother. And so it happens that amongst mammals brood-
care is more elaborate and complete than in any of the other groups
of the animal kingdom. The young do not leave their parents until
they are well equipped to fight the battle of life for themselves.
The maintenance of the species by the production of enormous
families has ceased. Some of the little rodents may breed several
times in the course of the year and produce rather large litters, and
there are some fecund mammals, such as pigs, where the litter may
contain a dozen or even more. But these are rare exceptions. In
the vast majority of cases, mammals breed no more than once a
year, and in some instances only once in every two or three years.
The usual numbers are one, two or three at a birth, and the higher
in the scale of mammalian life one looks, the smaller is the number
that is usual.
PLATE IX

FEMALE CAPPED LANGUR MONKEY
AND YOUNG

The drawing shows in two positions a mother and her baby
a few days after the young one was born in the London
Zoological Gardens.
 

 

 

 

 

Sg

Ones

 

 
BROOD-CARE AMONG MAMMALS 165

The preparation for the birth of the young is seldom a serious
matter amongst mammals. Those which have not natural homes,
and a good many of the others, do not seem to be aware of the
approaching event almost until the actual birth begins, and merely
follow the natural instinct of animals that do not feel quite well.
They retire from their companions and seek a sheltered place.
Nothing is known as to birth in the case of the man-like apes in the
wild state, and I do not know of any instance where they have bred
in captivity. Baboons, cercopitheques, langurs, macaques and many
of the small American monkeys have bred in captivity. The
female which is about to be a mother generally shows an enlarge-
ment of the breasts and a slight restlessness for a day or two before
the actual birth ; sometimes she ceases to take food and retires into
her shelter or sleeping-box, to appear again with her infant. The
capped langur monkey which is shown with her baby in two
positions on the plate (IX) seemed to have been as much taken by
surprise as her keeper in the London Zoological Gardens. The birth
took place at night, and the mother, from the marks in the cage,
must have dragged about the astonishing object she found until the
placenta got broken off. By morning, however, she had grown accus-
tomed to the baby and carried it pressed against her breast, from
time to time thrusting the head outwards and eagerly looking at it.
The baby clung tightly to the mother with both its arms round her,
and its long tail hanging down. When the mother leapt about her
cage, or went to the outdoor compartment, the baby itself clung
toher. It was only when the mother was at rest that she supported
it with her arms. For several weeks the baby never left her
and she showed endless curiosity and pleasure in it, ceaselessly
examining it, turning it over, stroking it and keeping it clean with
her hands. She was jealous of visitors, and, when they approached,
she used to turn round so as to hide the baby from them. The
father, in case of accident, had been taken away and put in the
adjoining cage, which was shut off bya piece of canvas. He madea
hole in this, and from time to time, especially when the mother or
baby made any noise, he would raise the torn fap and peep through.
In about a month the baby sometimes left the mother, but rushed
back to her at the slightest sign of danger. Apart from feeding it
at the breast, this mother, like all other monkeys I have ever seen,
made no attempt to give its young food or to share food with it. A
Japanese ape born in the London Zoological Gardens grew up with its
father and mother. Whenit was quite young the mother and young
166 CHILDHOOD OF ANIMALS

behaved in exactly the same way as the langur and her baby, and
the father took a lively interest in his child, but did not share in
protecting it in any way. Later on, when the young ape began to
take food itself, the parents did not scramble with it for dainties,
in the usual fashion of monkeys living together, but they showed no
signs of sharing food. Marmosets breed quite often in captivity,
the birth usually taking place in the sleeping-box. They often
show a perverted instinct which is not infrequent amongst
mammals, but very rare in the case of monkeys. In the first day
or two the mother may kill and eat her young. In the carni-
vores this perhaps is not so surprising. When the cubs are feeble,
or die from natural causes, it would not be unnatural for a carnivorous
mother to eat them, and it happens more often with young and
inexperienced mothers who neglect their young. But it also occurs
in the case of many animals that are not carnivorous, where the
conditions are favourable and the young apparently healthy. A
good many animals eat the after-birth, which is said to contain a
substance that excites the secretion of milk, and the eating of the
young may be suggested by the habit.

Lemurs often breed in captivity and are extremely good mothers.
As in man and true monkeys, there is usually only one at a birth.
It clings firmly to the mother, lying horizontally across the lower
part of her abdomen, holding on by its hands and feet and with its
long tail twisted round the back of the mother. The mother,
however, helps to support the baby by her own tail, which she
usually curls up between her legs over the body of the infant and
then twists round her own body. Later on, when the young is more
active, it is often carried on the back of the mother. For the first
day or two the mother sits upright with the baby lying across her
abdomen, and bends over it from time to time with a low crooning
noise. Male lemurs take no interest in their young and have no
share in protecting them. The plate (X) shows a black-headed
lemur with its baby, born in the London Zoological Gardens,
drawn a few days after birth. The text-figure (Fig. 30) shows the
young of another lemur, when much older, being carried on the
mother’s back.

In all the carnivores the young are born in a helpless con-
dition, usually blind, although new-born lions can see, and remain
with the mother, sometimes with both parents, for a period ranging
from a few weeks in some of the smaller creatures to even more
than ayear. The large predaceous creatures cover great distances in
PLATE X

FEMALE BLACK-HEADED LEMUR
.AND YOUNG

The plate shows the mother with her baby in two positions
a few days after the young one was born in the London
Zoological Gardens.
 

 

 

 

 

 
BROOD-CARE AMONG MAMMALS 167

pursuit of their prey, but usually have permanent headquarters
which they use by day if they are nocturnal, or at night if they
hunt by day. The lair is in a well-concealed place, capable of
defence, in the middle of a thick forest-brake, or
in dense reeds, or in a rocky recess in the side of ¢
a hill, or in a hole, burrow or hollow tree. In
captivity, the mothers always retreat to the
darkest corner of their enclosure to bring forth

their young, and one of the necessities for
successful breeding is to provide a
suitable shelter for this purpose. i
It is often useful to provide two, :
for the mother, even if she be
not disturbed, is restless
after the cubs are born,
and frequently — will
carry them from one
place to another
until she finds
a nook to her
liking. It
iS -in
the
first
few days
that the
young run
the greatest
risk of being
eaten by the
mother. A #

  

Ty,
“eal

    
  
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
   
 
 
 
  

A

 

 
 

bed of soft

dry earth,

of Hes Fic. 30. Ring-tailed Lemur carrying
or litter, its young. (d/ter Pocock.)

is fre-

quently scraped up beforehand. When pumas live in a place
where there are not natural caves or rocky recesses they make
a lair of twigs and moss in some dense thicket, with an overarching
roof of evergreen canes. The early days of all carnivores are
spent in a nursery of this kind, and the mother takes scrupulous
168 CHILDHOOD OF ANIMALS

care to keep it sweet and clean, whilst she licks the cubs with her
rough tongue until they are able to look after their own toilet
or to lick and clean each other.

The duties of parental care among carnivores fall chiefly on the
mothers, and although lions and tigers and not a few of the larger
cats remain in pairs, the father takes little interest in the cubs. For
the first few days the mother does not leave her family even to feed,
but afterwards she has to leave them from time to time to go out
hunting on her own account. Almost the first sign of independent
life in young carnivores is their power of wailing and screaming ;
they are very noisy babies, and in captivity, when cubs are expected
and the mother has retired to her sleeping-den, her guardians know
when the happy event has taken place by hearing the squealing
of the cubs. Polar bear cubs have loud, shrill voices and seem to
cry almost continuously from the moment they are born. Lion and
tiger cubs, leopard and jaguar cubs, have thinner and smaller voices
at first, but in a few weeks wail like cats. The voice of a caracal
cub, when it is so young that it cannot yet stand upright, can be
heard all over a house if the little creature has been shut up alone.
Hunger is certainly not the chief reason why they cry out, for they
are as vehement after a good meal as before it. Cold is sometimes
the cause of the complaint, because all young carnivores like to be
kept very warm, and will bask with comfort in front of a fire until
their fur feels hot to the touch. What they want is companionship,
and their loud shrieks when they are left alone guide the mother
to them, and she in return calls to them with a special note unlike
her usual purr orroar. Many carnivores, as, for instance, pumas and
caracals, practically never use their voices except in the breeding
season, and then chiefly as a call between the mother and the young.

The carnivorous mother always carries her young about in her
mouth, picking them up by the loose skin on the back of the neck,
and so carries them back to the lair if they have wandered from it,
or transports them to new quarters. Although the cubs or kittens
climb over the mother when she is lying down, she seldom carries
them except in her mouth. A polar bear in the London Zoological
Gardens, however, was noticed to carry her cub, not in her mouth, but
tucked under her arm. Itis generally supposed that the female polar
bear makes a burrow in the snowin late autumn, and that the
one or two cubs are born inside this and remain there throughout
the winter while the motherhibernates. The cubs are excessively
small compared with the size of the mother and grow very slowly
BROOD-CARE AMONG MAMMALS 169

for the first few months, whilst they are being suckled. But Arctic
explorers arefrequently visited by bears during winter, and polar bears
in captivity do not hibernate, nor show the slightest signs of being
less active and less ready to feed. It is much more probable that
these bears, in their native haunts, hunt seals along the edge of the
ice even in winter, and make only temporary burrows in the snow,
so that it may be their habit to transport their young from place to
place. Raccoons carry their young on their backs, and it is probable
that some of other carnivores that live in trees have similar habits.
Before they are weaned, young carnivores begin to scrape off
fragments of flesh from the prey that the mother has brought home
and so gradually acquire a taste for their future food. Before they
leave the lair they are taught the elements of stalking by the mother,
who lets them play with her tail, flicking about its tip, and training
them to seize hold of it and worry it. -As soon as they are strong
enough they are taken out by the mother, sometimes by both parents,
on foraging expeditions. Family parties of lions have often been
seen by African hunters. It seems that it takes nearly a year anda
half for young lions to learn the business of stalking. At first
they go out with the parents on short excursions and wait behind
until the kill has been made, when they rush in and follow the
example of the parents in tearing the prey to pieces. During
this time lions frequently prefer an easy prey, attacking flocks of
sheep or goats and killing more than they require for food. After
the first year, when the canine teeth are powerful, the young lions
are allowed to stalk and kill their own prey, but the parents watch
close at hand, to be ready with assistance if necessary. The young
animals at first do their work in a blundering fashion, and their kill
can be recognised by the clumsy way in which itis mauled. Pumas
go out hunting with the mother when they are only a few weeks old.
Polar bears teach their cubs to fish and to swim. The smaller
carnivores all have the same kind of early training. Young badgers
can often be seen playing with their mother at the edge of their
“earth ’’ when they are only three weeks old. Later on they go out
with her, trotting along in single file behind her in the hedgerows
and learning where to find what is good to eat and how to catch it.
Polecats, ferrets and weasels bring back small creatures such as mice
for their young to worry and eat, and later on take them out hunting.
Many of the animals which belong to the group of carnivores are
not really carnivorous, but live on fruits, shoots, seeds and other
vegetable matter, and they also learn from their mothers how to
170 CHILDHOOD OF ANIMALS

obtain food. That, however, is a less difficult business, and it is
the true hunters of living things that have most to learn. No
animal likes being caught andeaten, and the natural victims of the
carnivores have learnt intense wariness. They have acute senses
of smell and of hearing, and meet the cunning and strength of
their enemies with swiftness and prudence. The young carnivores
have to learn to stalk them against the wind, to lie in wait for them
at their drinking-places, to make the right springs at the right time,
and to strike the right blow with claws or teeth. And whilst they
are learning these things from their parents, and coming to a know-
ledge of their own weapons, they have also to learn to distinguish
between friend and prey, to use their teeth and claws, roughly
no doubt but only playfully, with their brothers and sisters and
parents, and to reserve the full strength of these for creatures they
wish to kill. It would be a shorter and simpler business if they had
to develop only their instincts of ferocity, to learn to use their
natural powers only for deadly purposes. But they have the double
lesson to learn and they do learn it. Certainly, carnivorous animals
will engage in fierce contests, especially from motives of rivalry or
jealousy, but in this they do not differ from other animals which
are not naturally predatory. As a group they are not the most
difficult to put together or to keep together, and, except for an occa-
sional quarrel over food or over a mate, even the fiercest carnivores
associate in peace, and are naturally friendly rather than quarrelsome
both with one another and with human beings, or even allied species.

The early life of ruminants is extremely different from that of
young carnivores. In the first place they are wanderers. They
have to travel long distances in search of water; they must migrate
from place to place to find the great bulk of vegetation, of young
foliage or herbage that they require as food. Even the large and
swift giraffe whose size protects it from all but the most powerful
of the carnivores, the strong and savage buffaloes which not infre-
quently repulse tigers successfully, the agile goats and mountain
antelopes which seek safety on the high pinnacles of rocks, and still
more the small and defenceless gazelles and brockets, keep alive only
by incessant watchfulness and by swift flight from their enemies.
They have no permanent home, but from day to day, from hour
to hour, almost from minute to minute they must be ready to rush
off. Their habit of rumination is itself an adaptation to this
shifting life. They do not chew their food as they crop it, but as
quickly as may be fill their huge paunches with a great
BROOD-CARE AMONG MAMMALS I7I

load of green vegetation, and then fly to a more sheltered place
to lie down and chew the cud. The mothers make no preparation
beforehand for their young, but retire for a few minutes to a thicket
and then drop the calves or lambs. One is the most usual number
at a birth, and twins or triplets are almost as rare as amongst human
beings. The young are born clothed with hair, with their eyes open
and their senses alert, and in a very short time, almost as soon as
the mother has licked them, are able to follow her. She then rejoins
the herd if the animals are gregarious. The mothers, however, are
very devoted to their young, and if there is a herd the bulls will
combine in defence of the cows with their calves, whilst in other
cases there is usually a family party consisting of the bull, one or
two cows and their calves.

A new-born giraffe is able to stand up in about twenty minutes,
and to run freely in a day or two ; in three weeks it begins to nibble
herbage and in four months to chew the cud. So also all young
ruminants begin to chew the cud only some weeks after birth, and
the young, during the earlier part of their life, resemble their non-
ruminating ancestors. Deer are rather feebler than most of the
ruminants at birth. Very often they have to be helped up by the
mother, and usually lie for two or three days in a thicket before they
are able to follow the parent. Wild cattle, sheep and goats are
able to move actively in a good deal less time than deer, and chamois
and antelopes are extremely active almost at once, beginning to
play and being able to follow the mother when they are a few
hours old. The young Springbuck represented on Plate XII
(p. 250) was drawn from a kid a few hours after its birth in the
London Zoological Gardens. Young camels are active and playful
and can move about almost at once. They begin to eat in a few
weeks, but suckle for nearly a year.

The Even-toed Ungulates that do not ruminate, the pigs, peccaries
and hippopotami, differ a good deal in their habits from the
ruminants. They are less disposed to seek safety in flight, the swine
and peccaries being well capable of defending themselves against
most enemies, and the hippopotami having few enemies to fear in the
rivers they inhabit. Wild swine and peccaries usually produce their
young in a dark and secret den, in the recesses of a cave, in deep brush-
wood, or even in the hollow of a huge tree trunk. The families are
rather large, a litter usually containing from four to a dozen, but
the smaller numbers are more frequent in wild animals than in the
domesticated races. The little pigs are feeble at birth and are
192 CHILDHOOD OF ANIMALS

sedulously guarded by the mother in her lair for about a fortnight;
after which they follow her abroad on her foraging expeditions, but
are carefully watched by her for many months. The hippopotamus
brings forth her young in a reedy thicket, generally on an island.
One is the usual number, and the baby is active from the first and is
able to swim before it can walk. In captivity a hippopotamus has
been born actually in the water on more than one occasion, and
the mother has usually shown herself rather indifferent, whilst the
father takes no notice at all of the young one. In the wild state,
however, the young one stays with the mother for a long time,
probably for several years, and is carried on her back in the water.

 

Fic. 31. Hippopotamus carrying its young.

African travellers have described the sudden apparition of a small
hippopotamus above the water, rising up until it appeared to be
standing on the surface, but really being carried on the mother’s
back (Fig. 31). When the female reaches the bank, the little one
slips off and follows her on foot.

The Odd-toed Ungulates—the horses, asses and zebras, and the
tapirs and rhinoceroses—give birth almost invariably to a single
young one without having made any preparation beforehand. Foals
can see and stand in a few minutes after their birth, and, although
they are feeble on their legs, can very soon follow the mother. In
the wild condition these animals live in herds, and the stallions
combine to protect the mares and foals when they are attacked
by lions or wolves, but as they prefer to seek safety in flight, and as
the herd has to move about in search of food, the foals must be
active very soon. Tapirs are often born in captivity, and, like
horses, are active ina few minutes. Extremely little is known about
the breeding habits of rhinoceroses, but the young are plump,
BROOD-CARE AMONG MAMMALS 173

strong and active and follow the mother for a very long time,
for individuals nearly full grown and certainly six or seven years old
have been found running with the mother and still suckling. A
young African rhinoceros came to the London Zoological Gardens
in charge of a black boy, for whom it showed great affection,
screaming loudly when the boy went off, and giving a low “ whinny ”
of pleasure when he returned. It was a considerable time before
the young animal would take either milk or sugar-cane, the two
chief parts of its food, from any one except its special guardian.

Elephants are much more active creatures than is easy to suppose
from watching their sedate and leisurely gait in captivity. They
travel enormous distances, moving very quickly and climbing almost
precipitous mountain slopes with skill, lightness and agility. A
single calf is produced at a birth and is able to move and follow
the mother almost at once. The mother is devoted, incessantly
stroking the young with her trunk, and defending it rather
savagely from any rash intruder. The baby suckles with its
mouth in. the ordinary fashion of a young mammal, and does
not use its trunk for drinking or even for picking up food for
some weeks. The calf remains with the mother for several years
until it is very well grown.

The dassies, rock-rabbits or hyraxes, although they differ ex-
tremely in size from elephants, are probably as nearly related to
them as to any other living mammals. They live in rocks or in
tall forest trees and the mothers usually have a family of three.
The young hyraxes are about as big as rats and are thickly
covered with very dark hair. They are active from the first and
are carried by the mother on her back (Fig. 32). Although they are
often compared with rabbits, they are quite different in habit and
disposition, being extremely intelligent and affectionate and most
plucky and well capable of defending themselves. My young
tree-hyrax was once introduced by accident to a palm-civet, which,
although tame, was accustomed to try its teeth on everything and
was a good many times the size and weight of my little animal. The
hyrax, however, at once raised its hair almost like the spines on a
porcupine, opened its white dorsal patch and rushed in at the civet
with a loud shriek of challenge, gave it a sharp bite, and then
quickly sprang back a foot or two, and stood bristling and alert
ready for a second charge. This was unnecessary, as the civet was
routed and fled shrieking to its owner.

The flesh-eating carnivores amd the herbivorous ungulates form
174 CHILDHOOD OF ANIMALS

two of the most important and strongly contrasted groups of
mammals. The contrast is specially evident in the case of the
young. The baby carnivores are helpless at first and are produced

    
 

 
 
  

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Fic. 32. Tree-hyrax carrying its young.

in well-hidden lairs. For some time they depend entirely on the
devotion of their parents and are fed, protected and trained by them.
When they are quite small they are often carried about by the
mothers, usually in her mouth, but in a few rare cases in another
fashion, by polar bears under the arm, by raccoons on the back.
In their young days, when the mother goes hunting, she has to leave
the cubs behind, and if they wander, discovers them chiefly by the
voice. Itis only when they are weeks or months old that they begin
BROOD-CARE AMONG MAMMALS 175

to follow her. Young ungulates have to follow the mothers almost
from the first ; it is only in a few rare cases, such as the pigs, that they
are kept for any time ina lair. It is still rarer for them to be carried
by the mother ; the hippopotamus and the hyrax are very unusual
in this respect, and the former has habits different from those of
all other ungulates, whilst the latter belongs to a peculiar and isolated
group. Young ungulates, like all mammals, are suckled by the
mothers, but are not fed by her in any other way. Certainly parental
affection is strong, but it is the business of the young one to find, follow
and stick to the mother rather than for the mother, as amongst car-
nivores, to take the initiative. And the most important difference of
all is that whilst no doubt the young find the feeding-grounds by
following the mother, there is practically no real training of the
young by their parents.

The Insectivora are the living survivors of a very ancient type of
mammal, certainly older than the carnivores, and perhaps repre-
senting their ancestors. Most of them are small and shy creatures,
lurking by day in holes or burrows and coming out at night in
search of worms and beetles. The family is generally small, four
or five at most, and is born in a helpless condition, frequently blind
and nearly naked. The female hedgehog prepares a nest of
moss and leaves, placed so that it is sheltered from the rain, and
the naked young are too helpless even to roll themselves up at
first. In a week or two they begin to play, the spines harden, and
the mother teaches them their future diet by bringing worms and
beetles to them. The female shrew constructs a globular nest at the
end of a blind burrow and lines it with soft hair and leaves. Soalso
the mole selects a spot where two of its burrows meet, and constructs
a globular chamber, very different from the elaborate fortress
which is its usual home, to serve as a nursery for the helpless young.

The members of the huge group of rodents vary in size from the
South American capybara, which may reach four feet in length, to
the pigmy fieldmouse, the smallest of living mammals, and although
they are all gnawing, chiefly vegetarian creatures, differ much in
habits. Amongst them are the most prolific of mammals, but the
rapid rate of multiplication is achieved by the shortening of the
period of youth, and by the early age at which individuals begin to
breed, rather than by the size of the broods. In many cases there
are only two, three, or four born at a time, although there are some
cases where the number mayreach ten or a dozen. In most rodents
the young are born naked, blind and helpless, and the young depend
176 CHILDHOOD OF ANIMALS

on the mother until they are nearly full grown. I do not know of
any instances in which the males take care of the young ; generally
they either neglect them altogether or attack them and persecute
them. Ina few cases the young are born in a high state of develop-
ment, recalling that of the ruminants. Young hares are able to see
and to follow the mother in a few hours after they are born. Young
guinea-pigs are furred, have their eyes open and are active almost at
once, and in a few days begin to nibble. Agoutis differ from their
parents only in size at birth, and almost at once begin to run about
actively. Porcupines also have their eyes open when they are born ;
their spines are present, but are white and soft, and it is only in a few
days that they become hard and serve as a protection. In these
cases, however, the animals live more in the open without a per-
manent abiding-place and, like ruminants, have to escape from their
enemies by swiftness.

In most rodents brood-care begins before the young are born, and
the mother selects and prepares a nursery for her family. Rabbits
live in communities, and the burrows of a warren form a complicated
set of underground passages which lead into each other and are used
in common. The females, however, dig out circular chambers
opening off the main burrows, generally with two or three exits.
These they line with leaves, soft grass, and masses of fur plucked
from their own breasts, and the blind and naked young are guarded
for some weeks in these warm recesses. Squirrels construct winter
nests in the forks of branches and store provisions against hard
times. In early summer they build more open nests far out
on slender branches and there the blind and naked young are
cherished and protected for many months. Hamsters construct
most elaborate dwellings underground, and store up in them a great
provision of food for the wintcr, but in the breeding-season the
females hollow out larger and much less elaborate dwellings,
just under the surface of the ground, in which the naked young are
reared. All the rats and mice make most comfortable nurseries for
the young, collecting quantities of soft materials, such as wool, rags,
moss, paper, hair or feathers, and arranging them in a burrow or
hole. The harvest-mouse weaves a nest which can be compared
only with some of the most elaborate habitations constructed by
birds. It ismade of narrow grasses, woven carefully into a globe about
the size of a cricket ball, and is suspended to stout herbs or blades
of corn. The walls are very thin, and there is no special opening,
the mother squeezing out or in through the meshes. The family
BROOD-CARE AMONG MAMMALS 177

is rather large, seven or eight being the usual number, and these lie
tightly packed inside the meshes of the nest. Dormice make a
nest of the same kind, but generally oval rather than globular, and
suspended high up in a thick hedge.

The elaborate dams which beavers make by cutting down trees,
collecting twigs and plastering over the tangled mass with mud, keep
the water at a constant level, and in the pools thus formed the
carefully built lodges are constructed. These always have an
entrance under the water and at least one on land. Small
branches are fastened to the dam and stored in the lodge, and in
winter when food is scarce the beavers take these above water and
strip off the bark and eat it. The special chambers in which the
young are born are lined with chips of wood quite differently
arranged from the stores of edible twigs. The young are
born naked and blind; the mother suckles them and keeps
them warm for a month-and then brings them twigs, the bark
of which they begin to eat. In six weeks they follow her out to
her usual haunts, but remain under her superintendence for two
years, after which they pair and set up in life for themselves. The
intelligence of beavers is much higher than that of other rodents, and
the long period of youth, under the tutelage of the mother, is
occupied in learning not only what is necessary to the individual,
but the art of living with other beavers in a well-disciplined com-
munity, doing work for the common good.

The beaver towns are only an extreme result of the gregarious
habits found in most members of the group. Even when the period
of youth is very short, and the mother is soon occupied with the
cares of a new family, the deserted young remain together for a
time. Young hares, when the mother has left them, haunt the
form in which they: were born, and play together for a good many
months until they are nearly full grown, when they have to scatter
because of the special risks of their mode of life in the open fields
and woods. More often rodents live together in some kind of
community, and it is very rare to find only a single pair in any suitable
place. Sometimes they burrow close together, forming assemblages
like the warrens of rabbits, or the villages of prairie-dogs or marmots.
Sometimes it is merely that they occupy the same corner of a wood
or field, the same group of trees or heap of rocks. They retain a
kind of communal instinct. Squirrels will desert a wood in a body,
and inthenorth great armies of them, simultaneously, for no apparent
reason, but especially in severe winters, move in a direct line over

C.A. M
178 CHILDHOOD OF ANIMALS

immense distances. The similar migrations of hares, Norway rats
and lemmings are still better known. The animals keep together by
an instinct of gregariousness, and will perish in great numbers if an
impassable river or branch of the sea lie across their chosen route.
Simultaneous migrations on a smaller scale frequently happen.
There is a fine colony of prairie-dogs living on a private estate in
Sussex. Recently a number of them, for no obvious reason, as
there was plenty of room and plenty of food, moved off more than a
mile, crossing very irregular ground, and settled down in another
field. Rats or mice will leave a particular house or ship almost
in a body, and this habit is useful when it is necessary to get
rid of these pests. If for some weeks a few are trapped or poisoned
every day, the whole body will desert the dangerous place, and even
newcomers, in search of convenient quarters, will refuse to settle
down for weeks or months.

Rodents usually follow the mother, and afterwards each other, in
single file, running along in well-marked tracks leading from their
bolt-holes to the feeding-grounds. The South American coypu;
a large aquatic rodent, makes a burrow in the bank of a lake or
stream with the aperture under the water-level, or, if there is not
a suitable position for this kind of nursery, constructs a platform-
nest in the thick reeds alongside a stream. Six to nine young are
produced at a time, active and furry, and are very soon able to follow
the mother to the water. There some of them climb on her back and
are carried about as she swims, whilst the others swim alongside.
The nipples of the milk glands, instead of being placed in the usual
fashion on the under surface of the mother, are arranged in a row at
each side, very high up and nearer the middle line of the back, so that
the young are able to suckle either as they swim alongside or as
they crouch on the back.

Very little is known as to the breeding habits of sloths, armadillos
and anteaters. Sloths spend their whole lives in trees, sluggishly
creeping along the lower sides of branches, to which they hang by
their curved claws. The young are born fully developed, no special
nest being made, and are carried about by the mother, clinging to
her hair with their long claws and clasping her firmly round the
neck with their arms. Anteaters use their powerful claws, not for
burrowing, but for digging out the ants and termites on which they
feed. They make a lair in thick brushwood, and so far as is known
produce a single young one at a time. This is fully clothed, and is
carried about by the mother on her back for many months. The
BROOD-CARE AMONG MAMMALS 179

armadillos and pangolins all burrow, digging out very large
chambers at the end of a long tunnel. In these the young are pro-
duced, usually three or four at a litter. The scales are at first pale
and soft, and the young remain in concealment for a considerable
time.

In all the marsupials the young are born in a very imperfect
condition and are at once attached to the teats of the mother.
These are placed far back on the body inside the marsupial pouch
when that is present. The number
of young at a birth varies, but
it is never very large, in most
cases one or two. The little
animals are blind and naked,
and even unable to suck. Each
is attached to a nipple, and its
mouth grows into a sort of tube,
which is sometimes so firmly
attached to the mother that it
cannot be torn away without
bleeding.

As the young are always carried
and kept warm by the body of
the mother, it is seldom that any
preparations are made before
birth. The little brush-tailed
wallaby, however, and the rabbit-
eared bandicoot seek out hollows
in the ground, and roof them over
skilfully with grass and twigs,
and a large number live in hollow
trees or scrape out burrows in the
soil. Whilst it is not so surprising that the mothers of young
born with fur more or less like thei: own, or of squeaking, soft little
creatures which snuggle against them and seek the nipple of their
own accord, should show maternal instinct, it is extraordinary that
a marsupial mother should even take notice of the naked, almost
inanimate and quite helpless offspring, and still more so that she
should take it up with her tongue and convey it to the nipple.

All the kangaroos, wallabies and their immediate allies have a
marsupial pouch in the female. This is a deep pocket in the furry
coat, with the mouth opening forwards and protected by a circular

   

Tree-kangaroo with young
in pouch,

  

Fic. 33.

 
180 CHILDHOOD OF ANIMALS

band of muscle so that the female can shut it up to an extremely
small hole or open it out widely. For a period lasting from a week
in the smaller ones to several weeks in the larger animals, the
infant remains motionless inside the pouch firmly attached to the
nipple. It is not even able to suck, but has to have the milk
squirted into its mouth by the mother. It then acquires a hairy
coat, leaves the nipple, and begins from time to time to push its head
out of the opening of the pouch and takes its first view of the world
(Fig. 33). Soon after its first appearance it begins to nibble, and
as the mother stoops down to crop grass or hay, the head of the
youngster is thrust out and it also begins to pick at food. Gradually
it learns to push out its head more and more, and even its fore-paws,
but as soon as the mother is startled and sits up to look towards
the source of danger, the young one retreats into the pouch, leaving
only its head with bright twinkling eyes visible. Still later on the
young one occasionally comes out of the pouch altogether, and
feeds on its own account, hopping near the mother. At the first
sign of danger, however, the mother stoops down, opens the pouch
widely, and the young one bolts into it head first, and then wriggles
round until it has reached its favourite position with only the head
protruding. Kangaroos give birth only once a year, and long after
the young one is much too big to enter the pouch it keeps with its
mother, and tries to suckle by thrusting its head into its former
home. Insome of the omnivorous and carnivorous marsupials, as,
for instance, the thylacine, the pouch opens backwards, and these
are quadrupedal in gait, not -hopping on their hind-legs and
tail like the kangaroos ; in others it is present only in the form of
temporary folds of the skin, and in others again there is no trace
of it.

All the marsupials, except perhaps the fierce thylacine and the
Tasmanian devil, are preyed on by other marsupials, or by large
eagles and other birds-of-prey, and escape by flight. Ifthe young are
small enough they are carried in the pouch of the mother, or run off
at her heels. In a few cases, however, especially in arboreal forms,
the young are carried on the back of the mother. The phalangers
leap rapidly from bough to bough, or run up almost vertical branches
with the greatest ease, and the females are often to be seen with one
or more young clinging to their fur. The little koala, or tree-bear
(Fig. 34), a gentle, inoffensive creature, carries its single cub on its
back. The American woolly opossums have long tails, the lower surface
of which is scaly and used for grasping branches. The females carry
BROOD-CARE AMONG MAMMALS 181

 

Fic. 34. Koala carrying its young.

 

Fic. 35. Opossum carrying its young.
182 CHILDHOOD OF ANIMALS

their young on their backs, and each little creature supports itself
by twisting the end of its tail round the tail of the mother (Fig. 35).
Male marsupials appear to take no interest in their families and
do not assist in any way in the work of protecting them.

Thus, in many different ways, first in the womb, afterwards at the
breast, keeping them warm, protecting and educating them, the
mothers of mammals are in very close relations with their young,
and in a smaller but considerable number of cases the fathers take
some part of the burden of bringing up the family. The first result is
an économy of life, fora much larger proportion of the young that are
born have a chance of escaping the perils of youth and inexperience
than in any other group of the animal kingdom. Next, this intimate
association has led to a high development of the emotional and
intellectual powers. In watching the relations between young
mammals and their mother, we cannot avoid using the words and the
ideas which we would use of the human race, and cannot doubt
but that affection and tenderness, devotion and anxiety are
experienced in the same way, if not to the same degree, as amongst
human beings, and our kinship with animals is brought home to us
far more closely than by the best-reasoned anatomical arguments.
CHAPTER XII
THE FOOD OF YOUNG ANIMALS

WHATEVER be the diet of fully grown animals, the young
require food that is easy to digest and that contains much nutriment
in proportion to its bulk. Fully grown animals have strong diges-
tions and usually powerful jaws or teeth, or some other natural
tools with which they tear and grind and pulp great masses of
tough material and extract from it whatever nutritious matter it
may contain. Young animals cannot easily deal with such sub-
stances ; they must have their food in as concentrated a form as
possible, and composed of materials as like the substance of their
own flesh and blood as possible. It is curious that there is a similar
difference between the diet of green plants and that of their seedlings.
The mature plants stretch their leaves into the air, extracting
from the thin gases of the atmosphere the necessary chemical
substances to build up starch or sugar, whilst their rootlets, twisting
through the soil, pour out a corrosive juice which dissolves the
hard granules of mineral matter, and so enables them to absorb
other necessary materials. The young seedlings cannot subsist
on such a meagre fare; they live on the highly concentrated food
prepared for them and packed round them within the seed-wall,
and digest it by digestive juices not very different from those of
an animal. In mammals where the reduction of families and
parental care has reached its highest point, the first food and the
only food for some time after birth is milk prepared from the blood
of the mother, and this is the most complete food known.

The milk is secreted by the mammary glands which begin to
swell and become active even before the young are born, and in
healthy animals continue to give enough milk to feed the young
animals until they are large and strong enough to be weaned.
It is a striking fact that there is very little in the anatomy or the
habits of the lower vertebrates to give a clue to the origin of the
milk glands which all mammals possess, or of the habit of feeding

the young by a secretion from the skin of the mother. The skin
183
184 CHILDHOOD OF ANIMALS

of most fishes secretes an abundant mucus from little glands some-
times opening directly on the surface, sometimes into a set of
canals on the head and sides of the body. The secretion no doubt
helps to keep the skin smooth and soft and more fit to glide through
the water, and is also useful in washing off the spores of moulds
and fungi and other harmful parasites which might otherwise settle
on the body. It may also be protective by being offensive to other
animals. Living fish which have been captured and put in a
bucket of water usually discharge large quantities of mucus; two
or three hagfish put in a bucket may give off so much that the
sea-water almost sets in a jelly. Frogs, toads and newts also give
off an abundant slime which, besides its other useful properties,
certainly has an offensive taste and protects them from being
swallowed by many animals. A dog will not try to eat a frog or
toad twice. In reptiles the skin glands are not so profusely
scattered over the body; they are larger and arranged in definite
places, and the skin as a whole is dry. Why so many persons
believe that serpents are slimy I do not know; their skin is always
absolutely dry. In lizards there are usually rows of skin glands
along the inner side of the thighs ; in turtles and tortoises on the
soft skin between the junction of the upper and lower “ shells,”
and sometimes under the chin. Crocodiles have large skin glands
on the lower jaw, and snakes near the anus, whilst in some there
are smaller glands near the edges of the mouth. It is certain in
some cases and probable in others that the secretions of these
large glands have a strong odour, often musky or disagreeable
and often discharged when the animal is annoyed, as in the well-
known case of the common English grass snake. In birds the
skin generally is not glandular. There is a very large gland, the
preen gland on the back, with a nipple from which an oily secretion
is discharged, which the bird smears on its beak and uses to
preen the feathers. In some of the aquatic birds there is a pair
of glands on the lower jaw.

These various glands are protective, or odoriferous, and may
advertise the presence of their owners at the breeding time, but in
no case is their secretion employed to feed the young. In mammals
there are various masses of skin glands secreting odoriferous
substances in different parts of the body: on the feet of ruminants,
on the legs of horses, on the fore-arms of lemurs, on the tails of dogs
and wolves, on the backs of peccaries and hyraces, on the faces
of antelopes and deer, on the temple of elephants, near the anus
THE FOOD OF YOUNG ANIMALS 185

of carnivores, and in many other situations, and it is these which
may be most easily compared with the special glands of reptiles.
Mammals have also two kinds of skin glands not found in other
animals : the sweat glands which pour out a watery secretion that
is partly a waste product and partly helps to regulate the tempera-
ture by cooling the over-heated skin, and the sebaceous glands
which discharge an oily fluid at the roots of the hairs which auto-
matically keeps them soft and flexible. The milk glands of
all mammals * are simply masses of much enlarged sebaceous
glands, and milk is an oily fluid to be compared with the ordinary
sebaceous fluid. By what stages this became turned into milk
and used for the feeding of the young it is very difficult to under-
stand.

However they may have come into existence, the mammary
glands of all mammals secrete milk in sufficient quantities for the
young and of much the same nature in every case. I should have
said the mammary glands of all female mammals, because although
the structures exist in the males, they are rudimentary, and although
in some abnormal instances they may secrete a small quantity of
a milky fluid, the suckling of the young is entirely the work of the
females. The milk of different mammals differs slightly in colour,
taste and odour, but these qualities are of little importance, and
just as the flesh of all mammals consists of the same kinds of sub-
stances in slightly different proportions, so the only food used to
build up the flesh of young mammals consists of the same kinds of
chemical materials.

By far the greater part of the weight of the body of an animal is
made up of the water its tissues contain, and so from seventy
to ninety per cent. of milk is water. Next in importance come the
very complicated nitrogenous substances known as proteins, of
which the most familiar example is the white of an egg. In milk
the proteins form from one and a half to ten per cent., and are
present as casein, the chief component of the curd which is formed
when acid is added, and albumin, which becomes solid when milk
is boiled. Protein builds up the vital framework of the tissues ;
muscle, nerve, every living part of the body is simply living protein.
In a fully grown animal protein does little more than repair waste,
and under perfectly healthy conditions only so much protein is
required in the food as is necessary to repair the wear and tear of

* The statement, common in text-books, that the mammary glands of mono-
tremes are derived from sweat glands and are therefore different from those of all
other mammals, is erroneous.
186 CHILDHOOD OF ANIMALS

life. In the young and growing body a much larger proportion
of protein is necessary, as the tissues themselves are growing and
have to be built up. Next comes the fat, which rises to the surface
in the form of cream, or can be separated as butter. In different
milk it varies in quantity from about one per cent. to ten per cent.
and is present in different chemical forms. Fats are used to a very
small extent in the actual building of the framework of the body.
They are burnt in the tissues to supply heat and energy. The fats
are suspended as little globules in the liquid of the milk and give
it a white appearance. All milk contains sugar in proportions
ranging from three to seven per cent. Milk sugar is chemically
different from cane sugar or grape sugar, and also differs in different
animals. The sugar of mares’ milk, for instance, can be fermented;
producing alcohol, and this property is employed to make weak
fermented beverages such as the well-known kephir and kumiss of
the Caucasus and the Russian steppes; the lactose or milk sugar
of cows’ milk does not ferment in this way. The sugars, like the
fats, play little part in the actual composition of tissues, but serve
as fuel. Lastly, all milk contains a small amount of dissolved
mineral matter, the ash which is left when it is dried and burnt,
and this is practically the same as the ash when flesh is similarly
treated.

Although in a general way the milk of all animals is similar, as
it has to build up and nourish tissues which are similar, there are
striking practical differences. Unfortunately we do not know very
much about the exact constitution and properties of milk except
in a small number of animals, but we do know enough to re-
cognise four distinct types adapted to four types of structure.
I can explain this best by giving a Table which sets out the main
facts, and then taking the four groups in turn. In the first column
I have given the kinds of animals to which the types belong. In
the second and third columns I have taken the whole cubical
capacity of the stomach and intestines at 100 and set down the
relative proportions of the stomach capacity and the intestinal
capacity. Next follows the nature of the curdling, the kind of
change which occurs when the milk is mixed with the digestive
fluids of the stomach, and in the last four columns the percentages
of the four chief substances of which milk is composed. The Table
must not be taken as an accurately worked-out scientific statement
of the case, because there is not sufficient knowledge for this, but
only as true in a general way.
THE FOOD OF YOUNG ANIMALS 187
Types of Milk

 

tal di
Total digestive Percentage of chief constituents

 

 

 

 

capacity=100 .
Kind of animals Kind of
Intes- curdling ;
Stomach tikes Water | Protein Fat Sugar
1. Herbivores

which chew the : 3
cud, e.g. cow, 70 30 | Solid 5 4 4 5
antelope

2. Herbivores
which do not Lik
chew the cud, 10 90 4 - 90 2 I 7
e.g. horse, rhino- jeny
ceros
3. Man and the Loose
apes and 20 80 | and 88 1:5 3.0 75
monkeys lumpy
. Carnivores, e.g. .
- ot oat ae \ 70 30 =| Solid 75 10 10 3

 

 

 

 

 

 

 

 

 

 

The animals in the first group are the ruminants, but they do
not chew the cud during the stage of their life when they are living
chiefly on mother’s milk. The capacity of the stomach and of the
intestines is enormous, but in early life the intestines, and especially
the cecum, or capacious blind gut, remain narrow, and the result
is that the greater part of the digestion takes place in the stomach.
The milk forms a solid mass of curd when it is acted on by the
ferments produced by the wall of the stomach. The curd remains
five hours at least in the stomach and is not passed into the intestines
until it is fully digested and ready to be absorbed. .

Exactly opposite conditions exist in the herbivorous animals
which do not chew the cud, such as horses and tapirs and the:
rhinoceros. In these also the whole capacity of the digestive canal.
is great, but it is differently distributed, for even in the young foal
the intestines are nearly nine times as capacious as the stomach.
The milk when it is acted on by the digestive juices forms a soft,
gelatinous curd which passes very easily out of the stomach into
the intestines, remaining in the former organ rather less than two
hours. The chief work of the digestive juices as well as the absorp-
tion of the digested material take place in the intestines.
188 CHILDHOOD OF ANIMALS

In man and the apes the stomach is also very small in proportion
to the capacity of the intestines, although not so small as in the
horse and rhinoceros. The milk forms a very loose curd, broken
up into small soft lumps, when it is acted on by the digestive juices,
and remains rather longer in the stomach than in the case of the
horse, but not so long as in the calf, and the work of digestion is
shared rather equally by stomach and intestines.

In the carnivores the total capacity of the digestive tract is
small, but the stomach, just as in the calf, is more than twice as
capacious as the intestines. The milk forms a very dense and solid
curd, which, also as in the calf, cannot possibly pass into the intes-
tines until it has been dissolved by the digestive juices. And so
it remains for a long time, about five hours, in the stomach, and
is nearly ready to be absorbed when it passes into the intestines.

There is nothing more important in the feeding of all animals,
young or old, than not to put fresh food into the stomach until it
has passed the last meal into the intestines, and still better until
it has had a rest after being emptied. Under natural circumstances,
when both the mother and young are healthy, there is little need
to attempt to regulate this. The quantity of milk secreted by the
mother and the rate at which it is formed supply more or less the
right amounts for the wants of the young, and there is a good deal
of natural elasticity as to quantities. Few young animals, left to
themselves, will take too much milk at a time; if they happen
to do so, they get rid of it by the simple method of throwing it up ;
the overloaded stomach, as it churns the milk, cannot press it into
the intestines and so forces it back into the mouth. Even when
animals are being fed artificially, there is not much danger in giving
them too much at a time; very little observation will show the
quantity they can conveniently retain, and they should be allowed
to take this, if it be certain that the proper time has elapsed
since the last meal. Nature also regulates the intervals between
meals rather well. The restless feeling of hunger, which drives an
animal to move about until it finds the nipple, starts from the
stomach, and under healthy conditions only from a stomach which
has been empty for some little time. In artificial feeding, the hours
should be carefully fixed. In the case of horses, and the other
members of the second group where digestion is chiefly intestinal
and the stomach is small, two hours is a proper interval between
meals, with a rather longer rest once a day, preferably at night.
In the case of man and monkeys, the interval should be from three
THE FOOD OF YOUNG ANIMALS 189

to four hours, and in the case of ruminants and carnivores at least
five to six hours. These intervals apply to quite young animals,
living only on milk ; when they are older, and especially when other
substances are added to the diet, the intervals may be made still
longer. The important point to remember is thai it is far better
to give too long an interval than too short a rest between meals.
In artificial feeding of young mammals, it is extremely necessary
that each meal should be given from perfectly fresh and clean
vessels, as the young are most sensitive to the slightest trace of
putrefaction. It is also useful, at least until the animals are fairly
strong and active, to give the milk as hot as they can take it without
being scalded. There are many forms of feeding bottles and arti-
ficial nipples used for young animals, but it is really preferable to
feed them with a spoon, an egg-spoon for very tiny things, and a
large kitchen spoon for larger animals. Spoon-feeding can be
made much more sanitary, as an open implement can be dis-
infected thoroughly, and it is more easy to regulate the quantity
and to prevent an eager little creature from choking than if it be
given a nipple. Itis surprising how quickly almost any kind of little
mammal learns to be handled at feeding time, and to assist by
opening its mouth for each spoonful. Moreover this method
establishes a relation of confidence between the young animal and
its guardian which is often of the greatest use in case of sickness.
A small sick mammal often refuses to eat and still more to take
medicine, and if it is unaccustomed to be hand-fed, the struggle to
make it swallow is difficult and dangerous. If it has become
accustomed to have a towel put round it (a process that at first
frightens most older animals very much indeed), to have its mouth
opened and a spoon used, it will submit to this even when it is
well grown and capable of making a serious fight. Not only can
it be fed, but many little operations such as cutting claws, removing
milk-teeth, or applying disinfectants can be carried out without
binding or gagging, which, however skilfully performed, always
upset the patient.

The four columns on the right of the Table show the relative
proportions of the chief substances in milk only in a very general
way. There are important minor differences in the nature
of the proteins, fats and sugars not only between the different
types but between the milks of different animals in the same type,
and there is no doubt but that its natural milk is the best food for
any animal. In cases of artificial feeding, however, this is usually
190 CHILDHOOD OF ANIMALS

impossible, and fortunately young animals are sufficiently adaptable
to make it possible to rear them on milk of another type than their
own, if a rough correction of proportions be made.

Cows’ milk is usually the most easy to obtain, and it will serve
in an unchanged form for any of the ruminant herbivorous creatures,
although in practice it is often diluted with hot water, especially
for deer. It is not suitable for horses, tapirs, or rhinoceroses, in
two ways. In the first place it contains twice the right proportion
of protein, much too much fat and not nearly enough sugar ; and
in the next place the solid curd that it forms will not pass sufficiently
quickly out of the stomach. Two of these defects may be put right
by one change. If rather less than its own bulk of very thin barley-
water be added, then the proportion of protein will be nearly
right, and the mixture, instead of forming a solid mass of curd in
the stomach, will remain in a liquid state so that it can pass at the
proper time into the intestines. There will still be too much fat,
but this is of little importance, and can easily be remedied, if thought
better, by skimming off a little of the cream before the mixture
is made. It will contain far too little sugar, and a heaped tea-
spoonful should be added for each pint of the mixture.

The adaptation of cows’ milk for the infants of human beings or
monkeys is more complicated. To break up the curd, it should be
diluted with a little more than its own bulk of thin barley-gruel
made with malted barley. This will make the proportion of protein
nearly right, but will reduce the fat far too much and the sugar still
more. A small teaspoonful of cream and a good teaspoonful of
sugar should be added to about the quantity of the mixture that
would fill a large teacup.

Probably because we are accustomed to see cows’ milk diluted
when it is being prepared for babies, most persons are naturally
inclined to add water to it for carnivores such as kittens and puppies.
This is quite wrong. In the first place the stomachs of these
animals are adapted for digesting a solid curd, and the dilution
of the milk would prevent this. Next, the milk of carnivores is
excessively rich in proteins and in fats, and it is necessary to
strengthen cows’ milk to make it suitable. One of the simplest
ways of preparing milk for carnivores is to add to each teacupful of
cows’ milk a good teaspoonful of condensed unsweetened milk,
and a similar quantity of cream or of olive oil.

When cows’ milk is not available, or when, as sometimes happens,
young animals are not thriving on a mixture made up from it,
THE FOOD OF YOUNG ANIMALS I9t

there are many useful brands of condensed milk which can be
employed. Those which are unsweetened are most easy to work
with, and the well-known “Ideal” brand serves well. If Ideal
milk be diluted with nearly twice its bulk of plain warm water, it
will contain fairly exactly the right proportions of proteins, fats
and sugar for ruminating herbivores. To use it for animals like
the horse, rhinoceros and tapir, it should be diluted with not quite
four times its bulk of thin barley-water, and will then be nearly
correct so far as proteins go, but some sugar should be added. It
will still contain a slight excess of fat, but this is of little importance
and may be neglected. To prepare it for young monkeys, it should
be diluted with rather more than four times its bulk of barley-
water, which will bring the protein nearly right and the fat almost
exactly right, but sugar must be added. To prepare it for carni-
vores, a very little warm water should be added, not more than just
enough to make it possible to feed the animal with it. It will
contain too much sugar, but this may be neglected, and not quite
enough protein, which may be easily put right by adding a squeeze
of raw meat juice.

The milk of individual animals of the same species varies so much
that very exact measurements of the proportions of the different
substances are not worth the trouble of making. The really neces-
sary things to observe are the proper intervals between feeding for
the different types of animals, and the proper dilution or enriching
of the milk, the warming of it before giving it while the animals
are very young, and the most scrupulous cleanliness and fresh-
ness of everything used. If it be at all possible, not more than
enough for one meal should be mixed at one time, and all the waste
should be thrown away, and a fresh start made for the next meal.
More young animals are lost from neglect of these precautions than
from any inexactness in the proportions or quantities used.

All young mammals pass gradually from a milk diet to the
ordinary food of their kind, and under natural conditions the
process of weaning is not abrupt. Young carnivores begin to pick
at scraps from the prey of the parents almost as soon as their eyes
are open and they are able to move about freely. When they are
being reared by hand, they should be given raw meat as soon as
they will take it freely, and the mistake of keeping them from it
too long is made more often than that of giving it to them too soon.
The cubs and kittens of all the cats, from the lion down to the
smallest wild cat, can digest raw meat very soon, and if they have
192 CHILDHOOD OF ANIMALS

been kept on milk slops, scraps of cooked meat with gravy and
vegetables and so forth, and are not doing well, a complete change
to raw meat is almost miraculous in its rapid effect. The meat
should be quite fresh, and it is better to change it, small rabbits,
sparrows and so forth alternating with beef, mutton or horse-flesh.
When the larger kinds of meat are given, bones with strips of flesh
attached are the most suitable form, as although bolting food does
them no harm, it is good that they should exercise their teeth and
jaws. I have no doubt but that all the cats, wolves, foxes, and
even the domestic dogs should be put on a raw meat diet as soon
as possible, and that they do best if they are kept on it. When
they are quite small, a meal twice or even three times a day, with
at least six hours’ interval, is advisable, but later on it should be
reduced to two meals and finally to one meal a day. It is the
natural instinct of these animals to growl and snarl over their
food, and it is extremely bad for their health and temper to tease
and disturb them while they are eating. However savage they
may have seemed to be, if they are left in peace they will come
to their friends immediately afterwards and sit down and wash
their faces and paws peacefully. The chief danger with uncooked
meat is infection from parasitic worms, which seems hardly possible
to avoid even by the most careful selection of the food given.
The animals should be watched carefully and their droppings
examined daily, and when there is need they should be starved
for twenty-four hours and then given a strong vermifuge, fed in the
usual way for two or three days, and then the starving and
drug repeated.

Apes and monkeys suckle for a long time and the change to
ordinary food is gradual. Young monkeys have been observed
very little in their natural surroundings, but as the parents do not
seem to bring food to them, they probably have to begin by nibbling
rough shoots and leaves, and probably most of them take grubs
and insects and even young birds and eggs. In captivity they are
dainty creatures, and it is even more important than with children
not to pamper them. If they are given nothing but carefully
cooked cereals, white bread and cultivated fruits when they
first begin to eat, they will refuse rougher and more wholesome
food. The digestive organs of monkeys are more capacious than those
of man, in proportion to their size, and the greedy animals will eat
until they can eat no more. Their food should contain plenty
of “ packing,” that is to say, it should not be too nutritious im
THE FOOD OF YOUNG ANIMALS 193

proportion to its bulk. Boiled potatoes, wholemeal bread, rather
hard apples, vegetables with plenty of fibre in them, should form
the bulk of their food, but they will not take such things if they are
accustomed to grapes and ripe bananas, sweet biscuits and carefully
prepared milk puddings. Young monkeys, even more than young
carnivores, should be accustomed to have their mouths opened,
and to be fed with a spoon. They are delicate, even when they are
not shut up in a warmed house and allowed free access to the open
air in all weathers, and one of the first symptoms of illness is the
refusal of food. They are almost as difficult to feed forcibly without
doing them damage as are hysterical women, unless they are
thoroughly accustomed, to being handled.

Young herbivorous animals of all kinds begin to pick at any
kind of vegetable food in a few days, although they may continue
to suck for months, or even years, until the mother ceases to give
milk. In captivity they should be encouraged to eat, but dry
foods of all kinds, especially dried leaves and clover, are most whole-
some for them. If they are being hand-reared, however, they
should not have free access to such food at all times until they have
begun to ruminate, but small quantitics should be given them
instead of one of their milk meals, and cleared away after a quarter
of an hour, or given immediately before a meal and similarly cleared
away. For that reason it is better to keep them on a litter such as
peat-moss, which they will not nibble, than on soft hay or straw.

The appetites of all young animals are very capricious if they
are not thriving, and unless they have been accustomed to hand-
feeding, they must be tempted in all sorts of ways, with all sorts of
flavours, before the last expedient of forcibly cramming them is
adopted. Quite a surprising number of different kinds of little
mammals can be persuaded, if some one sits down patiently beside
them and makes sucking and chewing noises and pretends to eat
the food. Monkeys are so like human beings that this device is
quite naturally successful in many cases. But I have used it myself
successfully with a caracal cub, a little hyrax, a bear cub, a puppy
and a young rabbit, and seen it employed with many other kinds
of animals. The most successful person I have ever seen in in-
ducing creatures to eat was an ignorant Irish peasant woman,
who treated them all as human infants, coaxing them, scolding
them and petting them. The great matter is to get them to eat
anything first, and then gradually to change them to a proper diet.
All sorts of unexpected flavours are occasionally relished by animals.

C.A. N
194 CHILDHOOD OF ANIMALS

A young orang, which had refused all food, was tempted to eat and
brought back to normal food and health on several occasions by
flavouring its milk with stewed rhubarb. A caracal kitten in
my possession liked the flavour of plum-tart excessively and
would take milk with this when it would touch nothing else.
A very young tree-hyrax was brought to me by a young engineer
who had obtained it in Nigeria and was unaware of its natural food.
Deciding that it might as well die from improper food as from starva-
tion, and that, in any event, he would give it a chance, he succeeded
by persuasion and force in getting it to take food which kept it alive,
but was certainly unnatural. When I took it over, I could not induce
it for some time to eat what I thought proper, but it tooka fancy to
sponge-fingers dipped in hot coffee and milk, from that passed to
strips of toast sopped in hot milk, which it would take only from the
hand, and then gradually learned to eat green leaves. But I had to
try many different kinds, until I found what it would always take ;
its favourite was hawthorn and next a very succulent grass. It
was given on one occasion bread sopped in claret and liked that
immensely, but could not be induced to touch bread if dipped into
moselle, or port, or champagne. It was extremely fond of ice
wafers, but took no special interest in them unless they were those
of a particular maker. The young elephant-seal in the London
Zoological Gardens, which ought to be purely a fish-eater, acquired
so voracious an appetite for buns that the public had to be warned
against feeding it. Once in the absence of the proper official I
had to try to give a young bear a dose of castor oil. After half an
hour’s struggle, in which the keeper and I both got scratched and
bitten and had our coats torn, we succeeded in forcing perhaps half
a teaspoonful down its throat. We gave it up, and as a last chance
I poured some out in a dish and left it in front of the bear, which at
once rushed at it, and greedily drank it all up. Patience and
experiment are the most successful methods with all animals.

I have already spoken of the care given by birds to the feeding of
the young. In the brush turkeys, probably alone among birds, it
does not occur, but the full-fledged chicks look after themselves
as soon as they are hatched. In the birds that are hatched in
‘a downy and active condition, the parents may actually bring
food, or may only call the attention of the young to food they
‘scratch up.

In ducks and geese the young are taken to food rather than
actually fed. In the vast army of birds which are hatched in a
THE FOOD OF YOUNG ANIMALS 195

helpless condition, the young are fed from the beginning. Since
the young of birds are either fed or watched by the parents, they
have the racial habit of confidence, and the new-hatched young
or the fledglings of even the shyest or fiercest of birds are all perfectly
ready to be fed by human beings, and only acquire their dread of
man when they are grown up. All that is necessary is to know
their habits, or to find out by experiment whether the food must be
thrown down for them to pick up or actually put into their mouths,
and they themselves assist by showing what they want. Most
birds that are hatched in a nearly naked condition must have the
food put in their mouths, and this applies also to most shore-birds
and aquatic birds, whilst most of the ground-birds and game-birds
pick it up for themselves.

I do not know of any instances in which the young of reptiles

are actually fed by their parents. They are hatched or born in an
active condition, and very quickly begin to eat on their own account.
By far the greatest number of them are carnivorous, and when
hey are small should be supplied with worms or grubs, very
small fish or frogs, or strips of meat cut into worm-like shapes, or
eggs broken open or even hard boiled and broken up. A few of
the lizards and the land tortoises are vegetarian and will eat fruit,
berries, lettuce and other green food, but even these will take also
slugs and grubs, particularly when they are young.

Reptiles are rather capricious feeders, especially in captivity, and
the difficulty is the greater because they all are able to fast for very
long periods without coming to harm, and it is not easy to know
‘at what point it is necessary to take active steps to make them
feed. It is certain, however, that young reptiles, like any other
young animals, cannot abstain from food for so long as fully grown
animals ; and especially when winter is approaching, a time when
the natural vitality of reptiles is at an ebb, it is necessary to see
that they begin their usually long fast with some good meals.
The vegetable feeders should be tempted with as many different
kinds of green food as can be obtained, until something that they
will take is found. Green leaves of clover are taken most readily
by small tortoises, and pieces of banana by vegetarian lizards.
A friend of mine told me that he had found out that if an obdurate
tortoise were put on its back, when it struggled to the right position
again it seemed to have been so surprised that it forgot its
former unwillingness and meekly began to feed at once. I have
tried this device myself, but with very infrequent success. Small
196 CHILDHOOD OF ANIMALS

alligators and crocodiles, and many little snakes and water-tortoises
are most readily tempted by small fish, other snakes and lizards
by small frogs, and chameleons by mealworms.

The surest device, however, 1s to warm the little reptiles well
before trying to feed them. Little alligators and crocodiles, small
water-tortoises and many little snakes will usually feed readily if
put first in a bowl of water heated to a temperature of about
100° Fahr., and snakes and lizards and land tortoises should be put
in front of a hot fire (with, of course, the chance of wriggling away if
they find it too hot) or taken into the hottest compartment of a
greenhouse. In the first winter of their life they should be wakened
up by this method and offered food at least once a week. When
‘they are older, if they have been well fed through the autumn and
are plump and heavy, they need not be disturbed.

If natural methods fail, cramming may be readily carried out with
most reptiles, and is sometimes successful. Itis comparatively easy,
because the gullet is wide and runs straight back to the stomach
from the line of the floor of the mouth, and there is little danger,
if use be made of a blunt instrument incapable of doing damage
to the back of the mouth and throat. Young crocodiles, alligators,
turtles or lizards should be held firmly with the left hand and
gently tickled along the soft skin near the hinge of the upper and
lower jaws until they gape, when a bolus of meat can easily be placed
far back in the mouth and pushed down the throat. Snakes have
to be handled more gently, partly because their ribs are very easily
broken when they struggle, and partly because if they wriggle, the
rather long gullet may not be straight and its wall be damaged.
I once saw a twenty-foot python being stuffed in a foreign Zoological
Collection. Its own keeper seized hold of it just behind the head
and pulled it out of its cage coil by coil, whilst a set of assistants
took their stations behind him, each grasping firmly a successive
portion of the snake as it was handed out. Finally, nine or ten
keepers in a row were holding the python and had much ado to
keep it straight. The food, which consisted of four skinned rabbits
arranged like a sausage on a long pole, had been prepared before-
hand. The keeper at the head then opened the jaws of the snake,
and a waiting expert slowly pushed the pole with the rabbits down
the throat of the snake until he had got it quite home. The pole
was then slowly withdrawn, and the rabbits were left behind, and
the mouth of the snake was cleaned and disinfected. The last
stage of the operation was to buckle a leather strap rather tightly
THE FOOD OF YOUNG ANIMALS 197

round the neck of the python, as otherwise it might have disgorged
the food that it had been compelled to take.

Cramming is not much in favour with those who are experts in
keeping reptiles, and it is alleged that very frequently stuffed
animals fail to digest their meal and die as the result of it. It
certainly is the case that the imperfectly digested remains of such
a meal are frequently found in fost-mortem examinations, but the
argument is not quite complete, because snakes that refuse their
food and have to be forcibly fed are usually in an unhealthy con-
dition.

This raises the very interesting and difficult question as to the
giving of a living prey to reptiles in captivity. The Buddhist
standpoint may be taken, and those who are of the opinion that
it is wrong under any circumstances to procure or connive at the
extinction of life may go the extreme length of refusing to give
mealworms or cockroaches to lizards, or worms and little fishes
and frogs to alligators and snakes. For most persons, however.
the doubtful point comes when it is a question, not of giving small
and unintelligent creatures to animals that will bolt them whole
and certainly kill them as instantaneously as can be done, but
of giving birds and mammals to large snakes. The problem, there-
fore, fortunately does not arise with very young snakes, but as
it is interesting and as I have given special attention to it, I may
digress to discuss it.

The large poisonous snakes when they are restless and show
that they are hungry generally dart at their prey as soon as it
is put in the cage, strike at it, inject the poison from their poison
fangs with the rapidity of lightning and then withdraw and wait
for some time before they proceed to swallow it. The victim dies
very quickly, as quickly as it can be killed by almost any method,
and, so far as it is possible to judge from its behaviour, painlessly.
So also when a constricting snake, like a python or anaconda,
is really hungry, and the expert keeper can almost unfailingly
recognise that condition, it strikes almost at once at the prey,
seizing it with its mouth, and with an indescribably rapid move-
ment throws one or two heavy loops of its body over it and
crushes it. If the animal struggles, further coils are thrown over,
and in a very short time the creature is smothered. Even if it
showed signs of being hungry, the snake generally waits some
time before beginning the long process of swallowing the prey,
which is always dead and sometimes quite cold first. When the
198 CHILDHOOD OF ANIMALS

snake is hungry and has proper accommodation to strike and
smother its victim, I think the actual death in this case, too, is
as often painless as when an animal is killed for human food.

It is necessary to insist, however, on the fact that in both cases
the prey is extremely seldom eaten for some time after it is dead.
If the mouse or rat, guinea-pig, duck, or goat has been first killed
by the keeper, and thrown into the cage of a really hungry snake,
the snake, whether poisonous or a constrictor, will behave exactly
as if the victim were alive, will strike at it and withdraw in the
one case, or strike at it and throw a coil over it in the other case,
and in time proceed to eat it as if it had not noticed the difference.
If the snake is not very active and has to be excited or tempted,
this can very often be done by dangling the dead prey at the
end of a pole or some other simple mechanical device. It is my
personal opinion that in nearly every case a snake, if it be kept
properly warm and not fed except when it is either hungry or
ought to be hungry, can be induced to take dead food. And
I have no doubt but that it digests the food which has been killed
by a keeper just as well as when it has killed it itself. My own
experience and observations have led me to believe, against the
opinion of many experts, that there is very little in the view that
the digestive secretions do not work properly unless the snake
has had the excitement of killing its own food. A hungry, healthy
snake has an excellent digestion, and can deal very well with
anything it has swallowed. I believe also that there is less than
nothing in the curious, half-superstitious notion that living food
is better for living snakes than dead food. The small snakes
certainly usually take their food alive, but they will take killed
food, if it is fresh, equally well, and the large snakes always wait
until their prey is dead before they eat it.

There remain, however, a small number of cases in which
individual snakes refuse all persuasion and would probably die
unless they are allowed to kill their victim. Such cases certainly
do occur, and those who have to deal with them must decide them
according to their own sense of what is right, whether to let the
snake die or to let it kill its prey. Some years ago, to make up
my own mind, I made a number of observations with my colleague,
Mr. R. I. Pocock, to ascertain the behaviour of different animals in the
presence of snakes. Clearly, if animals are really frightened in the
presence of snakes, there is much more than the mere fact that they
are killed and eaten to be considered before we use them as food,,
THE FOOD OF YOUNG ANIMALS 199

especially if the snake to be fed is not very active and does not
seize the prey at once. The usual animals used for food, besides
fish, frogs and worms, are pigeons, ducks, rats, rabbits, guinea-
pigs and goats. I have watched, very carefully, what happens
when these are put into the cage of a snake and are not seized at
once. At first, just like any animals put in a strange place, they
look about them, and if they are not quite tame they may bolt
to the darkest corner. Presently, however, they become at home.
The ducks waddle about, the pigeons preen their feathers, rats,
rabbits and guinea-pigs scamper all over the cage or sit up and
wash themselves, and goats behave precisely as they do in any
enclosure. None of them pay the slightest attention to the snake
if it is merely lying quiet, and I have seen all of them walk over
the snake and lie down on it or beside it with complete unconcern.
When the snake moves, they get out of its way or push against it,
just as they would do with a stick, or another harmless animal of
the same kind. They have no special dread of snakes, nor the
slightest instinctive fear or foreknowledge of their approaching
doom. We tried a further set of experiments by taking a large
tame snake, which was very active, to the houses in which various
animals were kept, and at the Royal Institution I repeated some
of these experiments in public, by introducing various animals in
turn to a snake, if they could be taken out of their cages, or by
holding the snake against the cage in which they were contained
and letting it move over the cage or even try to get its head through
the bars. The snake that was used was not a poisonous one, but
I should not expect animals to notice a difference to which very
few human beings would pay any attention. A great many different
ground-birds and water-birds were tested; fowls, pheasants, ducks;
geese, rails, coots and so forth either paid no attention to the
snake or tried to peck at it, in the fashion that they would
peck at any moving object. Parrots and cockatoos were equally
indifferent. A yellow-crested cockatoo which I had at the Royal
Institution amused us by being really frightened of a guinea-pig,
raising its crest and making a great fuss, but showing itself com-
pletely unconcerned when the snake writhed and twisted towards
it. Some of the more intelligent of the passerine birds, and in
especial an Indian hill mynah, showed their knowledge and dread
of the snake in the most definite way. The mynah’s cage had been
covered up, so that the snake appeared to it quite suddenly, and it
began to shriek in an excited way and darted up to the remotest part
200 CHILDHOOD OF ANIMALS

of the cage with so great a fear that we had to remove the snake
at once. Immediately afterwards the bird came to the bars and
pecked at my fingers in a friendly way, and showed the same atten-
tion to the guinea-pig. It was not a shy bird or timorous, but it
knew snakes and feared them.

Moreover,nearly every kind of mammal that we tried was indifferent
to snakes. Guinea-pigs and rats would run over them; a hyrax,
which is both intelligent and which from living in trees and on
rocks must often encounter snakes, was hardly even interested.
When the snake touched it with its tongue, the hyrax moved back
suddenly, just as when some one it did not know touched it, but
immediately afterwards stretched out and sniffed at the reptile,
and then, satisfied that it was not good to eat, took no further
notice. Small carnivores, dogs, foxes and wolves, sheep, antelopes
and deer, zebras and donkeys were either quite indifferent or came
up to the bars and sniffed, and then, deciding that the snake was
not a bun or piece of sugar, moved away with an air of wearied
disgust at having been deceived. As monkeys are well known to
recognise snakes, we tried nearly every different kind in the Zoo-
logical Gardens. Lemurs of all kinds have no dread of snakes and
show no trace of any knowledge of them. Without exception,
they all came to the bars of their cages expecting to be fed, and
tried to snap at the snake as they would at any kind of food. The
small American monkeys, which are less intelligent than the monkeys
of the Old World, were uncertain in their behaviour. Several
marmosets, although these are shy and timid creatures, and must
often be the victims of snakes in their native land, acted rather
like lemurs, being indifferent or very curious. Capuchins and
howlers, spider monkeys and woolly monkeys, however, nearly all
behaved like their Old World allies. And there is doubt as to the
recognition of snakes by the ordinary macaques and cercopitheques,
the baboons and mandrills. As soon as a snake is brought into
the monkey-house there is a great outcry. The first monkey that
sees it gives a peculiar scream and dashes off to the highest and
furthest part of the cage, and the others at once come to see what
is the matter, and in turn dash away. From the largest baboon
down to the smallest macaque all were equally frightened and
excited. At the Royal Institution I showed a snake successively
to a lemur, a very young cebus monkey and a young Arabian
baboon. The lemur had been born at the London Zoological
Gardens and probably had never seen a snake until that day ;
THE FOOD OF YOUNG ANIMALS 201

the two little monkeys were still very young, and had come to
the Gardens when they were such babies that almost certainly
they could have had no individual experience of snakes. The
difference in the behaviour of the lemur and the monkeys was
startling. The lemur, like all the others I had tried, was almost
aggressive in its want of fear; the monkeys were panic-stricken,
and the snake had to be removed at once.

The anthropoid apes in the Ape House at the London Zoological
Gardens were also tried with various kinds of snakes. The gibbons
were east timid ; a very small agile gibbon showed no fear and very
little curiosity, while a full-grown example of the same species
and a hoolock gibbon showed no panic, but retreated very decidedly.
It is possible that gibbons, as they are the most agile and completely
arboreal of all the monkeys, run little risk from snakes and
have partly lost their fear. The chimpanzees, except one baby
which took no notice, recognised the snakes at once and fled back-
wards, uttering a peculiar, soft warning cry. They then became
more excited and began to scream, getting high up on the branches
or wirework of their cages, but keeping their eyes fixed on the
enemy all the time. They soon took a little courage and drew
nearer in a body, chattering loudly, but fled off screaming again.
The panic in the presence of snakes was most sudden and complete
in the case of orangs. When I tried the experiment, there were
two unusually fine examples in the collection, one a large and
probably adult male, the other a well-grown young female that had
been two years in the Gardens and was very tame and gentle.
Both of these animals were usually most deliberate in their
movements, coming slowly across the cage even for their favourite
food, and climbing as if it were too much trouble to move. But
as soon as they caught sight of a snake and long before it was
near them, they fled silently, but with the most unusual celerity,
climbing as far out of reach as possible.

Most certainly it would be cruel to supply snakes with living
monkeys as food. Except for a few of the more intelligent passerine
birds, monkeys are the only animals with an instinctive deep-
seated terror of snakes. Such an instinctive terror does not exist
in most animals, and certainly there is no trace of it in any of the
birds and mammals, the frogs and fishes that are usually given
alive to snakes. The instinctive dread of snakes that so many,
perhaps most, human beings display is simply one of the many
legacies that we have inherited from our monkey-like ancestors,
202 CHILDHOOD OF ANIMALS

and we are quite wrong if we suppose that all animals or most
animals possess it.

Whilst I was making these observations, I was anxiously on the
watch for any signs of the fascination which so many persons say
is exercised by snakes on other animals, especially on birds. I
have now seen a very large number of birds and small animals in,
the presence of snakes, both under natural conditions and in cap-
tivity, but I have never seen any trace of what is described so often
and so graphically, of a bird or little mammal being fixed by the
beady glittering eye of its enemy, and then inevitably, drawn by
some invisible force, slipping down the branch or along the ground:
until it falls into the jaws of the reptile. What I have seen again
and again is a display of the power of attention. A sudden move-
ment may frighten away a bird or mammal at once, but if any object
—the tip of an umbrella, the human hand, or the head of a snake—
be pushed forwards very slowly and quietly, the bird or mammal:
turns round, fixes its attention on the moving spot, and if no sudden
noise or jerk be made, the umbrella or the hand may reach the
creature, or the snake come at striking distance of its victim. But
J have never seen any sign of the victim being, so to say, magnetised
or itself approaching the snake, and at any moment too great
eagerness on the part of the snake, or any sudden noise makes the
prey move off.

So far as I know, none of the toads, frogs, or newts helps to feed
the young. When the tadpoles get into water, they have to forage’
for themselves, and they are greedy, omnivorous creatures, hunting)
everywhere and not disdaining flesh, fish, or vegetable. They
have not the strength to attack large living creatures, but with
their horny jaws they are able to rasp and gnaw decaying animal
matter or the tissues of plants. When the tadpoles of frogs change
into little frogs, the digestive tract also changes. The intestinal
canal of the tadpole is very long in proportion to the size of the
creature, and is twisted up into a spiral, whilst the adult, which
is purely carnivorous or insectivorous, has a much shorter and
straighter digestive tube. Tadpoles seem to find their food much
more by smell than by sight. If they are accustomed to be fed on
shredded meat, they will pay no attention to it, if it be sealed in
a thin and transparent tube before being thrown into the water ;
but if a drop of meat juice be squeezed into the water in which they’
are swimming, the tadpoles at once become excited, and hunt in
every direction for the appetising substance. Frogs and toads,
THE FOOD OF YOUNG ANIMALS 203

on the other hand, select their prey by sight, and they quickly
starve if from any accident they become blind.

A set of very famous experiments was made many years ago on
the feeding of the tadpoles of the common frog. Young tadpoles
were believed not to have quite decided as to whether they were
going to become males or females, and their anatomy shows that
they retain at least a good many of the structures of both sexes
until they are nearly ready to go through the metamorphosis,
during which the organs of one sex develop and those of the other
degenerate. In an ordinary set of young tadpoles nearly ready
to become frogs, the sexes are fairly evenly balanced, but there is
a slight excess of females. E. Yung, a distinguished French
naturalist, fed one set of very young tadpoles entirely on beef until
they were nearly mature, a second set on fish and a third set on
the flesh of frogs. He found that in the first set the percentage
of females rose to 78, in the second to 81 and in the third to 92.
It seemed, in fact, as if the food most like the body of the adult,
and therefore most nutritious for the animal, favoured the produc-
tion of females, whilst a poorer fare led to the production of males.
Other observers have repeated the experiments, but with conflicting
results. I, myself, reared tadpoles for several successive summers,
feeding one set of a hundred on vegetable matter with very little
animal food, and another set entirely on animal food, and examining
the sexes afterwards. I got results that differed widely from year
to year. The chief trouble is that however carefully the tadpoles
be kept, with plenty of running water and with the removal of all
fragments of food soon after each meal, the mortality is very high,
and it is a fortunate result to rear twenty or thirty out of the hundred.
Similar attempts have been made to decide the sex of higher animals,
even of human beings, by the kind of food given to the mother
before the young are born, but there has been no success, and most
naturalists now believe that, at least in the vertebrate animals, the
sex is not determined by external conditions such as the nature of
the food.
CHAPTER XIII
THE TAMING OF YOUNG ANIMALS

PRIMITIVE man was a hunter almost before he had the intelligence
to use weapons, and from the earliest times he must have learned
something about the habits of the wild animals he pursued for food
or for pleasure, or from which he had to escape. It was probably
as a hunter that he first came to adopt young animals which he
found in the woods or the plains, and made the surprising discovery
that these were willing to remain under his protection and were
pleasing and useful. He passed gradually from being a hunter
to becoming a keeper of flocks and herds. From these early days
to the present time, the human race has taken an interest in the
lower animals, and yet extremely few have been really domesticated.
The living world would seem to offer an almost unlimited range of
creatures which might be turned to our profit, and as domesticated
animals minister to our comfort or convenience. And yet it seems
as if there were some obstacle rooted in the nature of animals or
in the powers of man, for the date of the adoption by man of the
few domesticated species lies in remote, prehistoric antiquity. The
surface of the earth has been explored, the physiology of breeding
and feeding has been studied, our knowledge of the animal kingdom
has been vastly increased, and yet there is hardly a beast bred in
the farmyard to-day with which the men who made stone weapons
were not acquainted and which they had not tamed. Most of the
domestic animals of Europe, America and Asia came originally
from Central Asia, and have spread thence in charge of their masters,
the primitive hunters who captured them.

No monkeys have been domesticated. Of the carnivores only
the cat and the dog are truly domesticated. Of the ungulates
there are horses and asses, pigs, cattle, sheep, goats and reindeer.
Among rodents there are rabbits and guinea-pigs, and possibly
some of the fancy breeds of rats and mice should be included.
Among birds there are pigeons, fowls, peacocks and guinea-

fowl, and aquatic birds such as swans, geese and ducks, whilst the.
204
THE TAMING OF YOUNG ANIMALS 205

only really domesticated passerine bird is the canary. Goldfish
are domesticated, and the invertebrate bees and silk-moths must not
be forgotten. It is not very easy to draw a line between domesticated
animals and animals that are often bred in partial or complete
captivity. Such antelopes as elands, fallow-deer, roe-deer, and
the ostriches of ostrich farms are on the border-line of being
domesticated.

It is also difficult to be quite certain as to what is meant by a
tame animal. Cockroaches usually scuttle away when they are
disturbed and seem to have learnt that human beings have a just
grievance against them. But many people have no horror of them.
A pretty girl, clean and dainty in her ways, and devoted to all
kinds of animals, used to like sitting in a kitchen that was infested
with these repulsive creatures, and told me that when she was
alone, they would run over her dress and were not in the least
startled when she took them up. I have heard of:a butterfly
which used to come and sip sugar from the hand of a lady, and
those who have kept spiders and ants declare that these intelligent
creatures learn to distinguish their friends. So also fish like the
great carp in the garden of the palace of Fontainebleau, and many
fishes in aquaria and private ponds learn to come to be fed. I
do not think, however, that these ought to be called tame animals.
Most of the wild animals in menageries very quickly learn to distin-
guish one person from another, to obey the call of their keeper
and to come to be fed, although certainly they would be dangerous
even to the keeper if he were to enter their cages. To my mind,
tameness is something more than merely coming to be fed, and
in fact many tame animals are least tame when they are feeding.
Young carnivores, for instance, which can be handled freely and
are affectionate, very seldom can be touched whilst they are feed-
ing. The real quality of tameness is that the tame animal is not
merely tolerant of the presence of man, not merely has learned to
associate him with food, but takes some kind of pleasure in human
company and shows some kind of affection.

On the other hand we must not take our idea of tameness merely
from the domesticated animals. These have been bred for many
generations, and those that were most wild, and that showed any
resistance to man, were killed or allowed to escape. Dogs are
always taken as the supreme example of tameness, and sentimen-
talists have almost exhausted the resources of language in praising
them. Like most people, I am very fond of dogs, but it is an
206 CHILDHOOD OF ANIMALS

affection without respect. Dogs breed freely in captivity, and
in the enormous period of time that has elapsed since the first
hunters adopted wild puppies, there has been a constant selection
by man, and every dog that showed any independence of spirit
has been killed off. Man has tried to produce a purely subservient
creature, and has succeeded in his task. No doubt a dog is faithful
and affectionate, but he would be shot or drowned, or ordered to
be destroyed by the local magistrate if he were otherwise. A small
vestige of the original spirit has been left in him, merely from the
ambition of his owners to possess an animal that will not bite
them, but will bite any one else. And even this watch-dog trait
is mechanical, for the guardian of the house will worry the harmless,
necessary postman, and welcome the bold burglar with fawning
delight. The dog is a slave, and the crowning evidence of his
docility, that he will fawn on the person who has beaten him, is
the result of his character having been bred out of him. The dog
is an engaging companion, an animated toy more diverting than
the cleverest piece of clockwork, but it is only our colossal vanity
that makes us take credit for the affection and faithfulness of our
own particular animal. The poor beast cannot help it; all else
has been bred out of him generations ago.

When wild animals become tame, they are really extending or
transferring to human beings the confidence and affection they
naturally give their mothers, and this view will be found to explain
more facts about tameness than any other. Every creature that
would naturally enjoy maternal (or, it would be better to say,
parental care, as the father sometimes shares in or takes upon him-
self the duty of guarding the young) is ready to transfer its devotion
to other animals or to human beings, if the way be made easy for
it, and if it be treated without too great violation of its natural
instincts. The capacity to be tamed is greatest in those animals
that remain longest with their parents and that are most intimately
associated with them. The capacity to learn new habits is greatest
in those animals which naturally learn most from their parents,
and in which the period of youth is not merely a period of growing,
a period of the awakening of instincts, but a time in which a
real education takes place. These capacities of being tamed and
of learning new habits are greater in the higher mammals than in
the lower mammals, in mammals than in birds, and in birds than
in reptiles. They are very much greater in very young animals,
where dependence on the parents is greatest, than in older animals,
THE TAMING OF YOUNG ANIMALS 207

‘and they gradually fade away as the animal grows up, and are
Jeast of all in fully grown and independent creatures of high intelli-
gence. These, because they are intelligent, may learn, even when
they have been captured as adults, that they have nothing to fear,
that the bars of their cage or the boundaries of their enclosure
not only restrain them from attacking persons outside, but restrain
the persons outside from disturbing them. Very fierce and fully
adult mammals will settle down quietly to captivity, will learn
that the visit of a keeper is a pleasant source of food, that cleaning
out the litter and washing the cage are not schemes to annoy them,
and almost in proportion to their intelligence will tolerate captivity.
The shyest of wild birds will breed peacefully a few inches from
the wirework of their enclosure, or will display complete fearless-
mess of the visitors who are on the other side of the fence, often
simply because birds that are naturally intelligent have learned to
'be shy in the wild condition, and equally learn not to be shy where
‘they are protected. Wood-pigeons in the open fields are amongst
the shyest and wariest of the native creatures of Great Britain,
but they have learned almost complete fearlessness in the London
parks. But these are not tame ; they have no pleasure in the society
of man or real confidence in him. These qualities can be acquired
only when the young creatures are taken over by man whilst they
are still young and when it is still their natural habit to be cherished
and protected. Later on in this chapter I shall say something
about the duration of tameness as young animals grow up. It
is clear; however, that we must be prepared to find that it may
not last. Just as it is the natural instinct of parents to cherish
their young, so also a time comes, except in gregarious animals,
when this instinct is reversed, and when the parents drive away
their young, and when the young themselves have to face the perils
‘of life with a wary suspicion and a fierceness that are extremely
different from their former habits. And even in gregarious animals,
a time comes when the savage battle of sex begins, and when
creatures that at all other times retain the friendly and gentle
habits of youth are dangerous to approach.

All young primates are gentle and easy to tame. The gorilla
is reported to be one of the most savage, as he is one of the most
powerful and well armed, of creatures. I do not think that any
adult gorilla has ever been captured alive. But young gorillas
are very well known, and many individuals have been brought to
Europe at ages varying from a few months to five or six years. J,
208 CHILDHOOD OF ANIMALS

myself, have seen five, of different ages. They were all extremely
gentle and affectionate, ready to make friends at once, and amazingly
intelligent. Unfortunately they are very delicate, and seldom
live more than a few weeks in this country. Although no animals
are more attractive and none is more to be desired in a Zoo-
logical Collection, I have refused, as Secretary of the Zoological
Society of London, to encourage their importation by dealers,
and now decline to purchase them. If some one who was really
fond of animals and intelligent in managing them were to obtain
specimens in West Africa, and were to keep them there until
they had become thoroughly accustomed to human society and
to the food that they would afterwards receive, I see no reason
why they should not be successfully reared, and I have no doubt
but that they would be found to surpass the other great apes in
the humanity of their intelligence as they do in size and structure.
Orangs are better known because, although they, too, are delicate,
they have been reared much more successfully in captivity. The
adults in their native woods, the steaming tropical forests of the
Malay Archipelago, are almost as suspicious of man as the gorilla,
and their enormous jaws and powerful hands and feet make them
dangerous foes. Young orangs are extraordinarily docile and
very affectionate, and have been taught many strange tricks—to
wear clothes, to sit at table for their food and to eat and drink
with spoons and cups. They are slow and sedate in their move-
ments, and as they are watchful and attentive, they quickly learn
what their keepers wish them to do. But although they are more
hardy than gorillas, they have to be kept under such careful condi-
tions and have lives so uncertain that their training has never
reached very great lengths.

Chimpanzees are much the most hardy of the anthropoid apes,
and their character and capacities are best known. They are all
extremely excitable, and occasionally fall into almost hysterical
fits of temper, when they scream loudly, and will bite even their
best friends, and as they have considerable strength and fight with
their teeth and hands and feet simultaneously, they are not always
quite safe. Because of this disposition, I dislike the use of chim-
panzees for performances at music-halls; I am afraid that not
infrequently they have to be beaten to bring them up to the
prompter’s bell, and I have noticed that the teeth of some of the
most advertised performing chimpanzees had been extracted or
broken off. Apart from occasional fits of temper, and if they
THE TAMING OF YOUNG ANIMALS 209

are weil treated and not unduly forced to do tricks when they are
unwilling, chimpanzees show extreme affection and docility. They
recognise their friends after long absences and show the greatest
excitement and joy when they return. It is unnecessary to describe
all that they have been taught to do; they ride cycles, perform
on the trapeze, put on and off clothes, open or close doors, help in
sweeping their cages, use forks and spoons, cups and drinking-glasses.
In the famous case of Sally, the late Professor Romanes, with the
patient help of Mansbridge, the keeper, taught that chimpanzee
a trick with straws which quite possibly implied the power of
counting up to five. Mansbridge has recently taught two young
chimpanzees in the London Zoological Gardens a very interesting
performance which they carry out at the command of his voice,
with little help from gestures. When he brings visitors to the
room, he unlocks the door from the outside and calls them to come
and open it. He then bids them salute, and they at once climb
on a shelf and, sitting alongside, place their right hands to their
foreheads. Next a cup of milk and a spoon are given to one of them
and he is told to feed his sister. He proceeds to feed her with the
spoon, until he is told that he may now take some himself. After
a varying number of spoonfuls, Mansbridge says, ‘“‘ Now put
down the spoon and drink it out of the cup,” which the animal
at once does. The older monkey is then given two pieces of apple
or banana, one large and one small, and told to give one to his
sister ; he has learned to select and give her the larger piece. If
there is a lady and a man amongst the visitors he is told to offer
a piece to them, and invariably carries out what he has been taught
by giving the larger bit to the lady and the smaller to the man,
certainly distinguishing between the pieces and the visitors without
any direction from the keeper.

Gibbons are less intelligent, but young gibbons soon become docile
and are always gentle and friendly. One of those now at the London
Zoological Gardens has been taught to swing round and round
a bar holding on by his hands, and to stop and reverse at the word
of command. All young baboons and African, Asiatic and Ameri-
can monkeys that I have seen are quite ready to become gentle
and tame and to take to human beings, and the various ingenious
tricks that they have been taught are well known. Lemurs are
less intelligent, but are equally ready to become tame.

Performing chimpanzees seldom live for more than a few years,
and I have never seen one that was nearly adult. At the Zoological

C.A. Oo
210 CHILDHOOD OF ANIMALS

Gardens, the chimpanzees as they grow up seem to me to become
less tame, but that may be partly because the keepers have to cease
being so familiar with them when they grow stronger, and when
considerable force would have to be used if they fell into a fit of
temper. The oldest chimpanzee in the London collection is cer-
tainly fully adult, as he is at least fifteen years old, and has remained
reasonably docile with his keeper, but is not quite safe with
others. For the same reason baboons and monkeys and lemurs
are not handled so freely as they grow up, but it certainly is my
opinion that apart from this, their tameness wears off.

All young monkeys are climbing animals, accustomed first to
cling to their parents and then to run along branches with the help
of their hands and feet. They dislike being caught hold of, and,
until they are really familiar with you, they will be frightened or
try to bite if you make any attempt to seize them. If, however,
they are allowed, they will climb on to you, running up your arm
and sitting on your shoulder, or clinging round your neck. This
applies not only to quite young monkeys but to many that are
full grown ; they will struggle and bite if you try to grasp them,
but they will readily allow themselves to be carried. When they
have become familiar, and are given an arm by which to hold
on, they will allow themselves to be groomed, to have their fur
combed and brushed, and their faces, feet and hands and the
naked parts of their body washed. One of the difficulties in keeping
monkeys is that it is almost impossible to train them to cleanly
habits. Like most arboreal animals, they have no special place
to keep clean and no natural disposition to avoid fouling their
blanket or the floor on which they are. I have seen a chimpanzee
that was trained to use a lavatory, but it plainly acted as if it were
one of the tricks that it had been taught to perform and did not
associate it with the object in view. It would go through the
operations when it had no need, and immediately afterwards would
foul the floor or its clothes. With regard to cleanliness, the most
careful training can only develop the natural instincts of animals.

I do not know any exception to the rule that carnivores, which
are naturally accustomed to maternal care, are easily tamed and
when young make gentle and affectionate pets. Baby tigers; lions,
leopards, cheetahs, caracals, lynxes, all the bears, hyenas, dogs,
wolves, foxes, and all the smaller creatures in the group attach
themselves extremely readily to man. As they are usually carried
in the mouth by the mother, unlike monkeys; they expect to be
THE TAMING OF YOUNG ANIMALS 2I1

picked up, and prefer firm, almost rough, handling. As the mother
licks them over and cleans them, they like being brushed and
scrubbed with a rough damp towel. Most of all they like being
caressed and petted and allowed to sleep snuggling in a warm lap.
Not food, but warmth and physical contact are the surest ways
to their affections. But all of them, and especially the cats, retain
a good deal of independence. They like to be left alone sometimes,
to retire into a particular dark corner which they have selected,
and will be rather unpleasant if they are dragged out when they
do not wish society. If they are left alone, they will soon come
back. To be fond of companionship is no peculiar gift of the dog.
All the carnivores dislike being left alone long, and will scream
loudly if they are shut up, or quickly learn the habits of their owners
and follow them from place to place.

It is no part of the domesticated nature of the cat and dog that
these are easy to train to cleanliness in a house. In their very
young days, the cubs and kittens of the catlike carnivores and of
the wolves and dogs and foxes are kept clean by the mothers, but
as soon as they are able to move about they are scrupulous in
avoiding the soiling of their bedding, or the floor of the room in
which they are kept, and if a box with sand, or better still with
fresh turf, is kept in a dark corner, they will find it themselves and
hardly have to be taught. It is almost a certain sign of illness in
any of these creatures if they become dirty in their habits. The
various small carnivores that live in trees, like palm-civets and so
forth, are a little more troublesome, but they are very easily taught.
When the teeth begin to develop, young carnivores naturally try
them on every possible object, living or inanimate, within their
reach, and it is necessary to teach them not to bite their owners,
as even in play they may do a good deal of damage. They even
bite their mother, until she teaches them, with rather sharp pats
from her paw, what it is permitted to bite and what is taboo. With
the different kinds of cats, from tigers to the domestic cat, a little
rap on the upper surface of the nose is the safest and most effectual
form of punishment. When this has been done once or twice, it
is quite enough to lay the finger on the nose, and the httle animal
will understand and remember. It is more difficult to teach them
not to use their claws when they get excited in play, or merely
when they are jumping or climbing on one. The claws of small
leopards, caracals and so forth are as sharp as needles, and when
they are quite young they dig them in automatically. Later on
212 CHILDHOOD OF ANIMALS

when they are older, they will romp in the wildest way, strike quite
hard blows with the paws, and submit to very rough handling
without unsheathing their claws. It is only when they are being
teased, especially over food, or when they are in a temper and
are lying on their backs refusing to be picked up, that there is
any danger of their striking with unsheathed weapons. It is safer,
however, to keep the points cut ; this is quite necessary when they
are babies, and if they have been accustomed to the process then,
they will allow it to be done when they are nearly grown up. Each
claw should be pressed out of its sheath in turn, and the end nipped
off with very sharp scissors or nail-clippers. The instrument must
be both strong and sharp, as the nails split rather easily. The
instinctive movements of young carnivores are fitted to retain
hold of a living, struggling prey, and the most certain way to be
bitten or clawed is to stretch out the hand timidly and try to draw
it back. The creatures must be seized firmly and at the first move-
ment, and if they put out their claws or close their teeth, do not
try to pull the hand away. They will do no further damage and
after holding on for a few minutes they will let go. Those who
handle young carnivores, however, must expect to be bitten or
scratched sometimes, either in temper or in p'ay, and disinfectants
should always be at hand and be applied at once. I do not think
that the little wounds from the teeth are often dangerous, but
the claws are always rather dirty and may easily convey disease
germs.

Carnivores have excellent memories and recognise their friends
even after years of absence. Mr. Carl Hagenbeck, of Hamburg,
who has probably handled and trained more young lions than any
other person, and as an important part of his business for many years
has been supplying performing animals to travelling menageries
and circus troupes, has told me that adult lions which he had not
seen for many years have welcomed him with every appearance
of pleasure. He is a man of iron nerve, with a great love of animals
and most unusual knowledge of their ways, and I have seen adult
lions that had been bred and reared in his establishment, but which
had not been specially trained, as friendly with him as if they had
been still young cubs. There is no doubt that such animals which
have been tamed and handled when they are young retain much
of their friendliness and docility. Animals that come to the Zoo-
logical Gardens as young and tame cubs generally remain much
more easy to deal with, and again and again, long after they had
THE TAMING OF YOUNG ANIMALS 213

ceased to be petted and handled, I have seen them welcome their
original owner. The same difficulty exists with carnivores which
have grown up as with the large apes. The danger of continuing
to treat them with unconcern is too great, as the result of a fit of
temper or a sudden fright might very readily be fatal to those
who had rashly ventured within their reach. It is certain, more-
over, that they distinguish acutely between persons, and an animal
that is quite tame with one keeper or person may be extremely
dangerous with others. They are extremely nervous, and the
slightest hesitation or want of resolution in approaching them
may alarm them and cause trouble. It is not quite certain, there-
fore, what would be the result of the experiment of continuing to
treat fully grown lions, tigers, bears and so forth with the same
familiarity as when they were cubs. With the smaller wild earni-
vores, however, there is no doubt that as they become adult the
natural instincts of predaceous creatures armed for destruction
tend to overrule their tameness. They cease to have complete
confidence in their owners, become wary and intensely suspicious
and wholly unsafe, at least with strangers. Even creatures so near
the dog as wolves, dingos and foxes, and most of the small carni-
vores, have to be given up as pets when they are adult. This is
simply following the natural order of events. In the wild condition,
apart from the influence of man, they are gentle and affectionate
when they are young, but when they are fully grown have to display
habits more suited for the unfriendly world in which they live.
Human influence retards but does aot prevent this inevitable and
necessary change. ,

Although I am inclined to admit, reluctantly, the truth of the
general belief that the friendliness of carnivores is an episode of
their youth, there are two other well-known popular beliefs about
them for which I have found no evidence. The first is the supposed
change in their habits at night. I have again and again been told,
with regard to young tame animals in my own possession, that
they might be safe by day, but that at night their prowling,
savage instincts would awaken, and that they would seize me by
the throat. Ihave often gone at night to play with nearly full-
grown young leopards, both the common leopards and snow
leopards, which knew me by day, and I have found them as
friendly and as gentle then as at any other time. A young tame
caracal slept nightly on a towel alongside my pillow until it was
nearly a year old, and although it was sometimes restless and
214 CHILDHOOD OF ANIMALS

would wake me up to be let out by patting my face, there was no
change in its behaviour at night or in the day.

We have all been familiar since we were children with the story
of the English officer in India who had brought up a young tiger
as a pet. One evening, when the tiger, now nearly full grown,
was lying by the side of his master, who was taking his ease in his
arm-chair, the faithful servant saw with horror that there was
a little trickle of blood from the hand of his master, and that the
tiger was eagerly licking it. Knowing that the first taste of blood
would arouse all the savage instincts of the animal, and that presently
his master would be devoured, the servant rushed for a rifle, and,
creeping up cautiously to the tiger, shot it through the heart. We
have all read the story, and most of us have been told it many times
by retired Anglo-Indians to whose intimate friends it had occurred,
but whose lives were fortunately spared to bear witness to other
familiar stories of the East. Young carnivores in this country are
not in the least excited by human blood. Long before they are
full grown they have become accustomed to the taste of fresh
blood, for there is no better occasional food for them than a freshly
killed sparrow, pigeon or young rabbit, according to their size.
When my own hand has been bleeding from an unlucky scratch
(and it may bleed a good deal) I have offered it again and again
to my young carnivorous friends, and they are not in the least
excited. They much prefer milk.

Young seals, sea-lions and walruses are extremely easy to tame.
It is quite certain that they remain with their mothers for a long
time and are very fond of companionship. As those that arrive
at the Zoological Gardens are generally young animals which have
recently been taken from their mothers, at first they mope very
much, and it is extremely difficult to induce them to eat or to be
consoled. It is curious that the seals which have most experience
of man, such as the grey seal and the common seal, seem to have
almost an inherited fear of him, and although they can be tamed,
do not settle down so quickly, and not infrequently pine and die.
Seals from remoter waters, such as the elephant seal from the
South Indian Ocean, the sea-lions from Africa, Patagonia and
California, and the walruses from the icy seas of the North become
reconciled to captivity almost at once. A similar difference between
the wild animals of civilised and populous countries and those of
remoter regions exists in many other cases. Fear of man is no
special instinct of animals; those that have little acquaintance
THE TAMING OF YOUNG ANIMALS 215

with him are curious about him rather than frightened of him,
but those that have been forced to make his acquaintance at close
quarters have had to learn to avoid him and fear him almost as a
condition of their existence. When seals of any kind do survive
the early days of their captivity, they become very tame and docile,
following their keepers from place to place and being anxious to
rub against them and nuzzle them. It must be even more difficult
for these animals than it is for the predaceous land carnivores to
learn the serious business of hunting, and it is probably only after
a long apprenticeship with their mothers that they become able
to find and to catch fish for themselves. It is not surprising there-
fore that they are friendly and attentive and have high powers of
intelligence. Common seals, grey seals and sea-lions have frequently
lived in zoological gardens long after they have become adult, and
I have never heard of a case in which they lost their tameness or
were in any way dangerous to their keepers. They are all gre-
garious, living in numbers in their favourite haunts, and certainly
giving one another warning of approaching danger, and it is only
in the breeding season that the males are savage, when they
engage in fierce battles and try to steal each other’s wives.

The young of hoofed animals are all accustomed to run with their
mother from their first days, and most of them readily transfer
their companionship to man. Few of them show any high degree
of intelligence, but they distinguish between individuals, recognis-
ing them both by voice and by smell, but to a much smaller extent
by sight. They like being stroked and fondled, but, except when
they are very young, resent being seized hold of or lifted, and are
extremely easily scared by any unusual sight or sound. Not only
do they follow their mothers when they are young, but most of them
are gregarious, and the herds or flocks are accustomed to follow
a leader. This is true even in the domesticated animals, and the
familiar English sight of a herdsman or shepherd driving his
animals with barking dogs and much shouting, or struggling with
a pig, is wholly unnatural. Ungulate animals, young or old, learn
to follow a human being as surely as they would naturally follow
their mother or the leader of their herd. Their affection, however,
is seldom much more than a fear of being left alone, a desire for
companionship, and the hope of getting some tit-bit to eat. Those
that are not domesticated seldom retain much regard for or con-
fidence in human beings after they have grown up, and nearly all
of them are dangerous in the breeding season.
216 CHILDHOOD OF ANIMALS

Even if they were suitable otherwise as pets, young tame ungulates
must be kept out of doors, for none of them, or almost none of them,
has the natural habit of cleanliness, and so they cannot be trained to
observe the proprieties. The best-known exceptions are the swine,
which will not foul their own litter if they have an opportunity of
choice, and will generally select a remote corner of their run to
deposit their droppings. One other exception was a great surprise
to me. My tame tree-hyrax, almost as soon as it came into my
possession, chose the old green baize cover of a typewriter, which
happened to have been thrown down in a corner of my study, and
afterwards remained faithful to this selection. When it was kept
ready for it, it would seek it out of its own accord, and when the
little animal was taken there at night, before going to bed, it at once
made use of it. The coney, another species of hyrax, is, accord-
ing to the Bible, “exceeding wise,’’ but this particular form of
wisdom was very unexpected, and very unlike the habits of other
hoofed animals.

Every one knows that young elephants are gentle, playful and
friendly, and that they attach themselves strongly to their keepers.
Their memory is very good, and neither young nor old elephants
forget an injury or a kindness easily. Their powers of climbing,
balancing and jumping, often seen in trained performing elephants,
are quite natural developments of their capacities, for elephants
are extremely active in their native haunts and climb steep rocks
very well. They usually retain their tameness when they grow
up, except at special seasons when males are dangerous. Their
docility is the result of their natural disposition, their long associa-
tion with their mother and their social habits. It is not due to
domestication. Even the Indian elephant is a tamed rather than
a domesticated animal. The stock is kept up much more by the
capture of wild animals than by breeding in captivity, and young
and old African elephants, which have not been domesticated in
the sense that has happened in Asia, are just as docile and easy to
manage.

I have already spoken repeatedly of the hyrax. It is in every
sense a wild animal, and although it has bred in captivity, I do
not know of this having gone on for more than one generation. Nor
do I know any one, except myself, who has had the good fortune
to own a tame tree-hyrax, but tame examples of the animal from
South Africa, East Africa and Syria have been known, and their
owners agree as to their engaging character. They are amusing,
THE TAMING OF YOUNG ANIMALS 217

very affectionate, and intelligent. They are expert and tireless
climbers, and no doubt as a result of their habit of riding on the
back of the mother, although they rather dislike being picked up,
they like sitting on the ankle or hand or shoulder. My pet rushes
to meet me as soon as I open the door of the room in which it has
been kept, after an absence. It roams all over my study, climbing
up the bookshelves wherever there is a vestige of foothold; I have
seen it climb on the back of a chair placed against the smooth,
polished front’ of a chest of drawers, stand on tiptoe and give a
little jump so that the tip of one of its front paws just reached the
top, and then pull itself up with the greatest ease. When it is
tired of playing, it climbs on my lap and goes to sleep quite un-
‘disturbed by my work on a typewriter, although it is startled by
every strange noise. It uses its flat, naked palm to give a sharp
rap on the floor or on the surface on which it may be resting when
it is angry or excited by the sight of a strange person or a strange
animal ; but this is also a call note, for when it has hidden behind
some books or in a dark corner, it comes out at once and runs to
me when I imitate the sound it makes. The fully grown hyrax
can defend itself well by giving sharp bites with its long incisor
teeth. My little animal, which is able to give quite a painful
pinch with its teeth, has learned to stop when I say “No,” and to
lay hold of my finger quite gently; it also will open its mouth
when I tell it to do so. Although the hyraxes are ungulates, they
stand very far away from the other ungulates and are probably
as nearly related to the ancestors of men and monkeys as to the
elephant and rhinoceros. They certainly have very little experience
of human beings, and their intelligence and capacity for being
tamed are genuine outcrops of their constitution and habits.

The domestic horse and donkey have been subjected to so many
generations of breeding that their qualities may be taken to be the
result of man’s preference rather than of natural disposition. Young
zebras, zebra-donkey and zebra-pony hybrids, and young wild
asses of every kind that I know are as tame and gentle and affection-
ate as the young of the domesticated races. Like these, they
readily learn to know their keeper and to follow him about, and
to be stroked and patted. When they become adult, however,
they very often are rather savage and treacherous, and some of the
wild asses are amongst the most dangerous of the animals that are
kept in captivity. What seems to have happened in the case of
the horse and the donkey is not that the nature of the young has
218 CHILDHOOD OF ANIMALS

been changed by domestication, but that spirit and independence
have been bred out of the race by getting rid of the adults which
showed “ vice,” the name that we apply to the qualities that do
not suit us. Tapirs, in my opinion, are stupid and rather un-
interesting animals. The young follow the mothers closely, and
parents and young interchange little shrill piping noises. Orphan
young tapirs will attach themselves to a keeper. They are harmless,
inoffensive creatures, but as they grow up become rather shy of
human beings. Two young but well-grown Malay tapirs, which
came to the London Zoological Gardens in 1912, allowed me to
handle them, to rub and slap their backs and necks the first time
I went into their enclosure.

The relations between a young hippopotamus and its mother
are intimate and long continued. I have seen very little of young
hippopotami and nothing at all of baby ones, but so far as I have
been able to find out, they are friendly and docile. The full-grown
animals, although they know their keepers well, are not to be trusted,
and if given the chance, would charge and do serious injury. The
young of all the swine and of the peccaries become tame almost
at once and show great affection for their owners. Young peccaries,
wart-hogs and river-hogs have often been brought to the London
Zoological Gardens by persons who had obtained them when they
were mere babies, and who all speak with delight of their intelligence
and devotion. As they are powerful, extremely active, and able
to give most dangerous wounds when they are full grown, familiarity
with them is generally dropped as they grow up, but they continue
to recognise their owners and to show pleasure at their presence for
many years.

Although camels have been domesticated for so long that
the truly wild animal is unknown to exist, they have never
really become tame. They know their masters and obey them
within limits, but most of them are ready to bite at any time and
do not discriminate between friend and stranger. Young camels,
certainly, are moderately docile and show some cupboard affection
for those who feed them. The South American llama and alpaca
have been domesticated almost as long as camels, but are less
obstinate and more gentle. The wild forms of them, the small
vicugna and the larger huanaco, are much more intelligent. They
are extraordinarily active, rearing on their hind-legs, and dancing
in the most curious ways. They recognise those who feed them,
and the single males of each species now alive in the London
THE TAMING OF YOUNG ANIMALS 219

Zoological Gardens have learned to recognise an individual visitor
both by her voice and by sight. They come rushing to her as she
approaches, and follow her to the front or the back of the enclosure,
grunting with pleasure and offering their special welcome by spitting
at her. Both of these are dangerous to their keepers. The vicugna
was brought from Patagonia by a Fellow of the Society, who had
obtained it when it was very young and with whom it was quite
tame and affectionate. After an absence of more than a year this
animal recognised and welcomed its original owner.

The fawns of all wild deer and the young of all wild cattle, sheep,
goats and antelopes readily attach themselves to man, submitting
to a good deal of handling, liking to be petted, recognising their
owners and readily following them. Equally I think they are all
uncertain when they are adult, the males at the breeding season,
and most of them, all the year round. There are differences in
temperament which are not easy to explain and which do not
depend on size or on habits, and of which the young show no trace.
Thus gnus are much more dangerous and ready to attack their
keepers than are elands, wild sheep are more combative than
wild goats, and some of the small gazelles and small deer are quite
savage.

I have little personal experience of young rodents except of
pet rabbits, which, like most boys, I used to keep, but these
have been so debased by domestication that their qualities are
not interesting. Jt is certain, however, that the young of all
rodents are easily tamed, and every one has seen or heard of tame
rats and mice, hares, dormice, squirrels, and so on. They recognise
their owners, like to snuggle against them, to climb on them, and
readily follow them about. They show in every way a willingness
to accept from human beings the attentions they would naturally
receive from their mothers. They belong to the set of animals
which on the whole dislike being laid hold of, and which are disposed
to bite any one who tries to grasp them, but are much more often
willing to climb on an extended hand or leg. How long their tame-
ness lasts it is difficult to say. We get a good many presented
to the Zoological Gardens because they have begun to bite, but I
suspect that in some cases it is merely because their owners do
not pay sufficient attention to the natural disposition of which I
have just spoken. We are too ready to treat all tame animals
like young carnivores, which do not in the least object to be grasped
and picked up and have no fear of being held; but most animals,
220 CHILDHOOD OF ANIMALS

although they do not forcibly resent such treatment when they
are very young, cease to submit to it as they grow older. If such
animals were treated with a due respect for their natural disposi-
tions, they might continue to be quite tame, although I do not
think that they have sufficient intelligence or memory to show much
difference in their response to their owners and to strangers. I
have seen, however, an old and fully grown capybara, the largest
of living rodents, which had been reared on a private estate, and
which knew its owner well and liked coming to be scratched and
fed with carrots or sugar, and I have been told of adult tame beavers
and agoutis.

Young insectivores such as moles, hedgehogs and shrews will
attach themselves in a rather stupid mechanical way to persons
who adopt them, and certainly like nestling in a warm hand, and
understand being fed, but I do not know of any of them remaining
really tame when they grow up. A hedgehog kept in a garden
will become accustomed to the presence of human beings and will
usually come to be fed, but even such animals stray if they are
given the opportunity. I have been unable to find anything about
the qualities of young edentates. Sloths in captivity are apathetic
and indifferent rather than tame. The great anteater is rather
more intelligent and certainly distinguishes between strangers and
those to whom it is accustomed, but armadillos are the most friendly
of all the edentates that I have seen alive, and I should guess that
they would make affectionate and fairly intelligent pets.

All the marsupial animals have a relatively low intelligence, and
few of them in captivity do more than learn not to be afraid of
visitors and keepers and to come to the bars to be fed. By the
time they leave the mother’s pouch permanently, they have the
mental characters of the adult, and I do not know of any case where
a very young marsupial has been removed from its mother and
been brought up by hand. The larger kangaroos occasionally
allow themselves to be handled, and some of the small nocturnal
opossums and phalangers submit to such treatment in a sleepy,
indifferent fashion. The thylacine, or striped marsupial wolf,
and the Tasmanian devil become gradually accustomed to their
keepers, but to a very much smaller extent than in the case of the
true carnivores. Their intelligence is very low, and they remain
shy, suspicious and ready to bite.

Young animals born in captivity are no more easy to tame than
those which have been taken from the mother in her native haunts.
THE TAMING OF YOUNG ANIMALS 227.

If they remain with the mother, they very often grow up even shyer
and more ntolerant of man than the mothers themselves. There
is no inherited docility or tameness, and a general survey of the
facts fully bears out my belief that the process of taming is almost
entirely a transference to human beings of the confidence and
affection that a young animal would naturally give its mother.
The process of domestication is different, and requires breeding
a race of animals in captivity for many generations, and gradually
weeding out those in which youthful tameness is replaced by the
wild instincts of adult life, and so creating a strain with new and
abnormal instincts.

Apart from whether or no it lasts after a young animal has grown
up, the degree to which tameness can be carried depends on the
natural habits of the animals concerned, on their intelligence and
on their inborn instincts. Taming should be no more than taking
advantage of the natural instincts and guiding them in a slightly
new direction. It is quite true that animals of high intelligence
can be trained to do many things entirely outside their natural
ange. If the animals have good memories and their trainer use
punishment freely, he can produce remarkable results, but I cannot
understand how persons who think that they are fond of animals
can endure seeing most of these tricks. A chimpanzee in evening
dress, lighting a cigarette and drinking brandy-and-soda on a
music-hall stage is a shameful abuse of man’s power over the ape’s
docility. Lions, tigers and polar bears snarling in a pyramid,
with the whip cracking and the iron bar and loaded pistol ready
to the hand of their trainer, can amuse only very stupid people, and
the performance is probably less dangerous than sword-swallowing.
CHAPTER XIV
THE PURPOSE OF YOUTH

ALTHOUGH it was not my intention in writing this book or in prepar-
ing the lectures on which it was founded to construct a carefully
considered and elaborate argument, I have tried to develop a general
idea and to illustrate it by selecting appropriate instances from
the abounding variety of nature. The period of childhood or youth
is peculiar to the living world and occurs, in the first place, merely
because most living things do not come into existence as fully
formed creatures like their parents, but as little specks of living
matter much more like the earliest forms of life that existed. It
has taken countless centuries for the living species of animals and
plants to evolve from the primitive forms of living beings, and yet
in each generation each new individual has to repeat the prodigious
process of changing from the minute cell known as the egg-cell,
which is separated from the tissues of its parent, to the complicated
adult body, often composed of myriads of cells, with different struc-
tures and functions, and built up into the elaborate architecture
of the adult. One of the little grains, of which you see thousands
in the hard roe of a herring, would presently have been shed into
sea-water, met and fused with another little speck of matter, but
so small that you cannot distinguish it without the aid of a micro-
scope, from the soft roe of another herring, would have absorbed
moisture and oxygen from the sea-water, and would have grown
visibly bigger, until presently it burst and gave birth to a minute
fish-like creature still very unlike a herring. This tiny transparent
living thing would have fed eagerly on still tinier specks of living
matter in the water, and in course of time, if it itself escaped being
eaten, would have turned to a swift and scaly fish, with a brain
and muscles, gills and red blood. The egg of a hen would seem
to have a task that is a little easier, for the little speck of living
matter inside the eggshell is packed round and round with rich
food, but the transformation of the liquid stuff that we see when

we break open a new-laid egg into the warm and feathered, hungry
222
THE PURPOSE OF YOUTH 223

and piping chick that breaks through the shell, is a marvellous
prodigy. That these changes should happen at all seems so miracu-
lous that perhaps it would not be more surprising if they happened
instantaneously. It may be unphilosophical to expect it, but at
least it is more comfortable to our intelligence that the growth
of the individual does take time. When the details of the process
are studied minutely, they are found to be gradual and orderly ;
the initial piece of living matter grows and divides, and the daughter-
pieces divide, much in the manner of free-living cells which are not
going to transform themselves into more complicated creatures.
The first set of daughter-cells becomes arranged in a fashion closely
resembling the structure of simple, living creatures which do not
proceed beyond such a stage, and so, step by step, with at each step
a Memory more or less definite of some free-living creature that
proceeds no further, the final complication of the new-born or new-
hatched young is reached. Again, it may be unphilosophical, but
it is comfortable to our intelligence, to recognise that the growth
of the individual is a faint reflection of the path of its ancestors
in the long evolution of life. The later phases of the development
of the individual, those that are passed through after it is hatched
or born, are not different in kind from the earlier or embryonic stages.
And so we come to see at least without surprise, if with less real
understanding than we are philosophically justified in claiming,
that living things pass through a period of childhood or youth,
and that that period is filled with memories of ancestral history.

In the development of many animals these memories of the past,
in embryonic and in larval stages, and in the period of youth, are
sometimes so precise and definite that they seem to give a clear
picture of at least part of the ancestral history. Such instances
are most common in the lower animals and in the lower members
of the higher classes. They tend to be blurred and condensed,
or omitted altogether. It seems, in fact, as if the first object of
nature were to get rid of evidence of past evolution, and to hurry
through each new creature as quickly and directly as possible to
its adult form.

Youth is a perilous time in the life of animals. The young things,
with their imperfect organs, with their relics of stages that were
fitted to the environment of a remote ancestor, but are out of gear
with existing conditions, are hampered with the cumbrous scaffolding
of the past and can offer feeble resistance to accidents and diseases.
They are a ready prey for a world of hungry enemies. It is in the
224 CHILDHOOD OF ANIMALS

first place imperative that this period of feebleness should be passed
through as quickly as possible. And evidence of a tendency to
shorten and simplify the development of the embryo or of the
larva, to remove all stages that have ceased to be useful and to
make straight the path from egg to adult is to be found in every
group of the animal kingdom, but is increasingly plain in the higher
groups and the higher members of every group.

The shortening and simplification are most complete in the em-
bryonic stages of development, whether these take place within
an eggshell or in the body of the mother. In free-living larve,
or in active young, protection is often obtained by new organs,
special habits, peculiar pattern and coloration that may have no
reference to the past history of the animal and no direct bearing
on its adult shape and form. Larval organs, habits and coloration
are not infrequently new interpolations in the life-history, the sole
purpose of which is to protect the larve and give them a chance
of coming to maturity. I confess that when I was beginning to
collect materials about young animals, I hoped to find that youthful
characters would sometimes show the direction in which the race
might be supposed to be going to develop. I thought that I should
find the exuberant vitality of youth displaying itself in new ways,
some of which might turn out to be useful and come to be adopted
by the adult. I can find no trace of such prophetic or tentative
efflorescence in structure, coloration or pattern, although, as I
shall show later, there is something comparable with it in the mental
qualities of youth. The physical characters of youth are sternly
economic. Special organs, new or old, are present because they
make it more possible for the creatures to escape the destruction
that is always treading on the heels of the young. Pattern and
coloration are either simply the ancestral garb of the parents still
retained, or the direct results of growth, or occasionally, and especially
in caterpillars, devices for the immediate protection of the young.
The youth of most animals is too hampered by the past, too harassed
by the present, for experiment in structure or coloration to be
possible.

The amazingly heavy mortality that presses on the young is
met in a great many cases by the enormous size of the families. I
have given instances of the almost incredible number of eggs that
are laid, of young animals that are turned adrift, a few of which
escape the perils that beset them and live to maintain the species.
This spendthrift fashion of reproduction, which bears witness to
THE PURPOSE OF YOUTH 225

the prodigality of Nature rather than to her inventiveness, is
gradually replaced by a new method. The number of the young
is very greatly reduced, and the small families are protected by
the parents. Sometimes the eggs are retained in the body of the
mother until they are nearly ready to hatch; sometimes they
hatch within her body and are fed from her blood; sometimes
even the eggshell is dispensed with, and from the earliest appearance
of the embryo as a separate speck of living matter, it is fed from
the blood of the mother. The eggs may be laid in places carefully
prepared by the mother or by both parents, and eggs and young
may be fed and guarded for long. The young, even if born in an
active condition, may be fed and protected by the parents for years
‘or months. Instead of hundreds of thousands of helpless young
dumped on a careless and hostile world, a very small number,
sometimes only a single individual, is produced at a time and cared
for in the most complete fashion.

In the highest animals, and especially in mammals, the young
are freed from the trouble of finding their own food ; they have very
seldom to defend themselves, and the changes from egg to embryo
‘and from embryo to adult are made as simple and direct as possible,
and none theless the duration of the period of youth increases as we
go up the scale of animal life. This lengthening of youth is specially
plain when we compare the different members of a single group.
If we take the human race and its allies, the apes, monkeys and
lemurs, then man, who is at the top of the scale, has the longest
youth, and even in the lower and less civilised races, it would be
‘unsafe to assign less than fifteen years to immaturity, whilst in
the higher and more civilised types it is still longer. The great
apes, the gorilla, orang and chimpanzee, take from eight to twelve
years to grow up. The baboons and common monkeys take from
three to eight years, and the little South American monkeys and
lemurs require only two to three years. If we take weight or
stature of the body, the strength of the muscles or any of the purely
physical qualities, we shall find that they do not fit this varying
scale of youth. There is only one part of the body that can be
reconciled with it.

In the figures (Fig. 36) I show the contour of the brain in a set
of primate animals drawn roughly to scale. It will be seen at
once that man, with the longest period of youth, has the largest
brain ; that although a chimpanzee may equal or exceed a man
in size and weight, its brain is much smaller; and that the brain

C.A. P
226 CHILDHOOD OF ANIMALS

of a macaque is still smaller, but larger than that of a cebus
monkey. It is better not to include lemurs in this series.
Although they are more closely related with apes and monkeys than
with any other living animals, they form an independent series, the
lowest members of which have smooth and small brains, yet the
higher members of which have brains which surpass in develop-
ment those of the lowest monkeys.

But there is a more important consideration even than size.
The cerebrum, the great mass of the brain that fills most of the
hollow of the skull, is smooth in the lowest forms save for a few faint
wrinkles, which become more conspicuous and more numerous
successively in the cebus, macaque and chimpanzee, until they
attain the high complexity shown in the human brain. The corre-
spondence is so close that we may say almost definitely that, at least
inside the great groups of mammals, the length of the period of
youth increases with the size and complexity of the brain.

Without going too deeply into anatomical details, we can take
the comparison a little further. If a slice cut through a cerebrum
be examined even with the naked eye, it will be seen to consist of
a greyish layer, closely following the external contour, and a deeper-
seated white mass. If you compare two stretches of coast occupying
roughly the same space on a map, as, for instance, the east coast
of Wicklow and Wexford with the south-west coasts of Kerry and
Cork, you will see at once that the coast-lines corresponding with
the same inland area may differ enormously in length, according
to whether they present an even front to the sea, or are twisted
into bays and fiords. So also in brains of nearly the same size,
the amount of grey matter is much greater in one that is folded
and convoluted than in one that is nearly smooth. The duration
of youth in animals belonging to the same group varies with the
relative amounts of grey matter contained in their brains.

I am not going to discuss here whether the brain be an organ of
the mind, played on by some immaterial entity, as a musician plays
on a musical instrument, or whether mental qualities be emanations
of the brain as bile is a secretion of the liver. It is enough that
the mental powers are definitely associated with the grey matter,
and that their development and education write a record upon it.
The grey matter contains the nerve-cells of the brain. A fully
developed nerve-cell may be compared with a spider seated in the
centre of a web which is an actual set of outgrowths from itself.
Some of the fibres of the web are in connection with nerves ; indeed,
THE PURPOSE OF YOUTH 227

there are continuous fibres from the cells in the brain to the remotest
tissues of the body. Other fibres are continued to the web-fibres
of other brain-spiders. The sys-
tem might be compared with a
very complicated set of telephone
exchanges, each exchange supply-
ing a certain district near at hand
or far away, and each linked up
with a number of other exchanges
with their districts. The greater
the number of subscribers’ wires
to each exchange and the greater
the number of connections with
other exchanges, the more perfect
the system would be.

The details of the development
of the brain are difficult and
obscure, but there is a good deal
of evidence to show that the actual
number of brain-cells does not
increase during childhood, youth,
or adult life. The initial number
of cells may be taken as an index
or physical correlate of the natural
endowment. Species or indi-
viduals with many of them
in a given area have a richer
potentiality of mental life.
In the new-born mammal,
however, large numbers of
the brain-cells lie isolated
and quiescent in the grey
matter ; they are joined up
neither to each other nor to
distant parts of the body.
In early infancy the brain
has little or no control over '
even the chief muscles and Fic. 36. Brains of Primates. The largest

  
  
  
 
 
   
 
 
  
 
 
  
  
  
 
 
 
  
 
 
 
 
 
 
 
 
 

; . 8 (lowest figure) is human; next, that of
tissues of the body. This is a chimpanzee; next, that of a macaque
probably the explanation of monkey; next (uppermost figure), that

: of a cebus monkey. (The figures are all
a famous observation much reduced to the same scale.)
228 CHILDHOOD OF ANIMALS

written about some years ago. It is known that at least some very
young infants will seize firmly any object which they can grasp. If
one be givena broom-handle of which to lay hold, it will swing from
this by one hand or by both hands, and even, by bending the muscles
of the arms, pull itselfup. When a little older an infant is unable
to do this. The suggestion was that in its extreme infancy
the young human being showed this sign of its monkey ancestry
and swung from the broom-handle as an ape would swing from
the branch of a tree. The objection was taken to such an interpreta-
tion that the action of the young infant was purely automatic,
that its brain-cells were not yet joined up to the lower centres which
control the automatic movements of the body. A frog the cerebrum
of which has been destroyed, if placed in a bowl of water, will go
on swimming indefinitely until it dies of exhaustion. The contact
of water with the skin makes the direct and automatic suggestion
to the lower nerve-centres which control the operation of swimming,
whilst if the brain were intact, sensations of hunger, of weariness,
of desire to escape and so forth would have come into play and
caused a change in the movement. The young infant is a brainless
creature, because the nerve-cells of its cerebrum are not yet linked
up with the rest of the body. On this view, however, the comparison
really becomes more interesting. The infant swinging from the
broomstick is not acting like full-grown apes, but like young apes
clinging to their mother. A new-born leopard, or mole, or hedgehog
would not cling to a broomstick in this way, but a new-born ape
or monkey does so. The automatism lasts longer in the ape than
in man and is less interfered with by the suggestions coming from
the brain, as throughout life there are fewer brain-cells and these
have less complete junctions with each other and with the lower
centres. There are many cases in the adult life of human beings
where the higher cells or some of them are temporarily thrown out
of action, so that they are in the same position as if they had ceased
to be joined up. And in such cases the behaviour of the patient
recalls that of apes and monkeys. When a normal healthy human
being is struggling or fighting with persons trying to seize him, he
uses only a small part of his muscular power, because the higher
centres of the brain are interfering and warning him that he has to
take care of himself, toavoid being hurt and even to avoid hurting
his opponents too much. But if he be mad, if some of the higher
brain-cells are temporarily put out of action, then he loses all
restraint, and fights, as a desperate animal fights, without any
THE PURPOSE OF YOUTH 229

thought of his own safety, and so exercises much more than his
ordinary strength. The events of some cases of somnambulism are
still more remarkable examples of what happens when the higher
cells of the brain are temporarily shut off from their control. Metch-
nikoff has collected a number of cases in which persons in the condi-
tion of somnambulism performed with sureness and agility feats
such as running up and down the steep roofs of houses, climbing
to vlaces that they could not have reached and where they certainly
would not have retained their balance had they been in the normal
condition. He suggests that these are real returns to the automatic
fearlessness and semi-conscious gymnastics of the great apes.

The period of youth in mammals is the time when the brain-cells
of the superficial grey matter increase in size, throw out fibres,
and come into more and more complex connection with each other
and with the different systems of the body. Just as the number
of these cells forms an index of the natural endowment of an
animal, so the extent to which these interconnections are developed
is a measure of the effect of education, in the widest sense of the
word. An animal with a smaller natural endowment might reach,
by a greater development of the initial stock, a higher mental plane
than another animal with many more cells that had remained
quiescent. No doubt a certain amount of development of these
cells takes place throughout the whole period of life, particularly
in the higher and more intelligent animals. But even in human
beings, at least in average cases, there appears to be comparatively
little further change in female brains after the age of fifteen, and
in male brains after that of twenty-four or twenty-five. In animals,
which after they have come to maturity seldom change the cha-
racter of their experiences or of their abilities much, it is probable
that the growth of the processes of the brain-cells practically is
limited to the period of youth. We may in fact say more definitely
that the period of youth is necessary for and is occupied by the
co-ordination of the brain-cells of the grey matter and the develop-
ment of a greater complexity of the intercommunications of these.

We are on safer ground, however, when we turn from the physical
mechanism of the mind to the mental qualities themselves, and
consider the effect of education on these, without too nice an inquiry
as to what is education of the body and what is education of the
mental qualities. We like to think that animals have instinct and
that we have intelligence, but the passage from one to the other is
gradual. All instinct can be modified to a certain extent by expe-
230 CHILDHOOD OF ANIMALS

rience, and there remains a strong instinctive side in intelligence.
The modifications of instinct may last only a very short time or
they may remain almost permanent. They may be not much
more than purely mechanical changes, as when a new pen after a
little use writes more smoothly, or the other kind of change that
is known as fatigue, as when a watch-spring, repeatedly used,
must be allowed a rest to recover its normal reaction. From these
simple changes the effects of experience on instinct grade up towards
memory, and at least in human beings into conscious memory.
The period of youth is the time when instinct is gradually broken
down and replaced by experimental action.

Let us get the matter clear by some examples of undoubted
instinct. A caterpillar is developed from an egg laid on a leaf.
It has never seen its mother. It has never done anything all
through its life, except eat when it was hungry (and that was most
of the time), crawl under the leaf when it rained, come out again
and resume eating when it was dry, and, perhaps, when it was
startled, drop suddenly down, spinning a thread of silk, by which
it re-ascended after a time. Suddenly, and once only in its lifetime,
it completely changes its habits. It spins silk without having
been disturbed, rolls itself up in a leaf and fastens the edges of
this blanket with threads of silk. All the caterpillars in the same
brood do this exactly in the same way and almost exactly at the
same time. They either accomplish their task correctly or bungle
it completely. There is no question of practice, or imitation, or
of learning. The necessary act is accomplished once and for all.
When I was at Oxford, I used to keep common garden spiders
in a cage, and found that when they were provided with twigs and
proper surfaces to which they could attach the anchoring spokes
of their webs, they spun these always exactly in the same way, and
that in watching them the action seemed so orderly and was so
completely fitted for its object that it was difficult not to think
of it as intelligent. But one of the spiders, placed under an inverted
bell-jar to which the threads would not remain fastened, quite
contentedly went through the exact routine of operations for making
a web, although the result was a meaningless wisp of threads. A
chick that has been blinded by covering its eyes with a hood almost
before it has got out of the shell, and that is kept blindfolded and
fed by hand for a day or two until it is strong, will peck at objects
unerringly as soon as it is allowed to see them, although it will not
at once distinguish between food and stones. My caracal cub
THE PURPOSE OF YOUTH 23%

was taken from its mother when it was just able to see, and not
nearly strong enough to stand upright on its legs. It was born
very early'in the year, in what turned out to be a cold spring, and
for at least three months it had no opportunity of seeing cither
another caracal, or even any kind of cat. It lived entirely with
human beings. It was accustomed to be washed and brushed care-
fully, and yet as soon as it was strong enough, it began to lick its
own paws, to wet them and use them to wash its face, precisely
in the fashion of its parents and of all their ancestors and of the
whole tribe of cats from time immemorial. It is easy to misin-
terpret instincts and to think of them as intelligent, or as meaning
more than they do. A well-known naturalist has related that once
he passed straight from stroking his dog to a litter of kittens two
days old and still blind. As soon as he touched them, the tiny
things began to hiss and spit, and he explained this as an instance
of the instinctive enmity of cats for dogs. But this was reading
too much into it. The spitting of the kittens was a generalised
reaction to sudden disturbance. Young ocelots, leopards or caracals
will hiss and spit at any unknown touch or smell. In a beautiful
passage in one of his plays, M. Frangois de Curel describes some
one watching rats playing in the moonlight in a courtyard shadowed
by plane-trees. Suddenly a large leaf flutters down from a bough
and the scared rats bolt in every direction. You are not to laugh
at them and think of them as silly, being scared by ashadow. The
plane leaf might have been some nocturnal bird of prey, and the
rat that waited to investigate the danger would not have lived to
benefit by the experience it had gained.

Instincts, whether they are complicated, like the spinning of a
web, or simple, like the sudden response to a disturbance, have not
to be learned and imply neither intelligence nor consciousness.
They either fit a very precise set of conditions, and if these are not
present they break down, or they are so vague and generalised that
they are not easy to distinguish from processes with which the
brain has nothing to do. If an unpleasant substance such as an
acid be applied to the leg of a frog, it will pull the leg away ; if the
leg be held, it will apply the other leg to the affected spot, and try
to rub the acid off. Such behaviour we certainly regard as a
simple kind of protective instinct, but, as it takes place as precisely
in a frog which has had its cerebrum destroyed as in an undamaged
animal, probably all such instincts are combinations, more or less
complicated, of the direct physical responses to stimulation which
222 CHILDHOOD OF ANIMALS

living matter displays. To analyse them into their constituent
parts is a kind of vital chemistry still beyond our power, and it is still
more difficult to understand the complex results, arising from their
combinations in different proportions, than it is for us to understand
how it is that when hydrogen and oxygen are combined in a particu-
lar proportion, the qualities of the resulting water are so different
from the qualities of the two elements. Still less do we understand,
although we know that it must exist, the physical machinery by
which these complex inborn instincts are worked and transmitted
from parent to offspring.

A few examples of some of the simpler elements out of which the
instincts are combined may make this difficult subject clearer.
They are what are known as tropisms, tendencies to turn towards,
or to turn away from, the source of physical stimulation, and are
found in all kinds of living matter, animal or vegetable. They
may be traced upwards to the most highly developed of living
beings, including ourselves, although in these latter they may be
disguised or controlled by the higher nerve-centres. The reaction
to light is known as phototropism or phototaxis. Many free-living
cells, especially the swarm-spores of plants, diatoms, and even
many colourless animal and vegetable organisms move in the direc-
tion of illumination, if the light be not too strong, but on over-
stimulation may move away from it. Other small organisms
move away from light towards darkness under all circumstances.
In some of the compound organisms this reaction to light, positive
or negative, may be shown by the direction of growth rather than
of locomotion, as when the shoot of a plant bends towards the light,
or its rootlet on emergence from the seed-capsule bends away from
it, and some of the plant-like compound polyps show precisely
similar reactions. Hydra bends towards light, some small worms
move towards it and others away from it. From these simple
reactions, we pass by easy transitions to the much more complicated
and yet more precise actions of the higher animals with eyes and
with definite nervous systems. Turn up a stone on the seashore
or a log of wood in a garden, and you will see numberless little
creatures disturbed by their exposure to light and at once setting
about wriggling, creeping or running, until they can get to darkness
again. The reaction begins before there is any trace of a definite
mechanism to produce it, and is continued up to those animals to
which even persons least inclined to assent to the existence of con-
sciousness in all living matter are quite ready to attribute some
THE PURPOSE OF YOUTH 233

form of consciousness. Very low in the series, too, we see the
simple reaction changing with the state of the creature to which
it is applied, the turning towards light, for instance, being reversed
to a turning away from it, when the stimulation reaches a certain
degree of intensity. And so long before the dawn of consciousness,
unless the term consciousness be so attenuated as to be meaningless,
we get a beginning of adaptive response.

The contact tropisms are other factors of instinct at first extremely
simple. A free-swimming, single-celled creature, animal or plant,
which comes in contact with an obstacle, responds in some way.
It may shrink back, sometimes with a little turning movement,
and advance again, and it may proceed by this system of trial and
error until it finds a way round. On the other hand, if an amceba
come across a solid surface, it at once creeps out over it, for it is
the habit of that creature to creep in contact with any flattened
surface, instead of drifting freely in the mud or water. A growing
rootlet burrows into every crevice, whilst a shoot moves in the
direction of free space and air. As we ascend the scale of the
animal kingdom, we find numberless creatures, low and high,
which exhibit such a choice with regard to surfaces. The stems
of polyps grown in a glass tank cling closely to the walls of the
vessel, but their upper portions, carrying the mouth and tentacles,
turn outwards towards the open space. Free-swimming larve
wriggle out of a crevice if they drift into it. Most marine worms
move about restlessly until they have an opportunity of burrowing
into sand, or of creeping into some chink in the rocks. A very
large number of insects, from cockroaches to ants, and whether
they are exposed to light or kept in the dark, will move about rest-
lessly until they can squeeze between the folds of a sheet of paper,
or into some similar place where they are in contact with a surface
all round. In an aquarium, pieces of drain-pipe have to be placed
for many different kinds of fish, such as eels and pike, whilst others
become restless if they are enclosed in such a fashion. So also
amongst reptiles, there are some which must be provided with
retreats into which they can creep, others which like to lie in the
open. Amongst mammals there are some that cannot be persuaded
to enter any box or chamber if it appear to be closed. Deer,
antelopes, cattle and sheep and most of the large carnivores can
be boxed only with the greatest trouble, sometimes by the device
of making the box apparently a narrow tunnel open at the end
turned away from the entrance. Such animals often damage
234 CHILDHOOD OF ANIMALS

themselves seriously in their endeavour to escape from a closed
chamber, but will be comparatively content if at least one of the
sides is protected by light bars. Another set of mammals, of which
the small rodents are the best-known instances, at once enter any
little hole or aperture and lie placidly in a closed chamber. In
higher animals these contact reactions naturally are modified by
other factors, such as positive and negative phototropisms, and
they are affected by mental factors, but none the less they are
linked up with the simplest responses given by single-celled organ-
isms. Traces of them survive even in man. In nervous subjects
the condition of claustrophobia is well known. Persons affected
by it have an almost hysterical dread of closed spaces. They will
hesitate to enter a very small room, to go down a narrow alley, to
sit in the middle of a row at the theatre, to ride in a closed carriage.
Victims of the opposite tendency are said to be affected with agora-
phobia. They have a fear of open spaces, will go round two sides
of a square rather than cross the open place, are happier in a crowd,
prefer a closed carriage, and so on.

Chemotropisms, or attraction to or repulsions from chemical
stimulation, occur not only in free-living cells but in the separate
cells and every part of the tissues of higher animals and plants.
Some microbes move towards a supply of oxygen, others away from
it, so that where such are mixed in a drop of water under the micro-
scope they will quickly arrange themselves in a pattern, one set
crowded in the centre, the other round the edges where the water
is in contact with the air. Weak alcohol repels most free-living
cells, weak acid attracts them. Some will move towards solutions
of sugar, others towards meat-juice diffusing in the water. One
observer found that when he had a number of ciliated animalcula
freely swimming in a drop of water under a thin slip of glass, he
could kill some of them by applying a hot needle to the surface of
the glass cover-slip. The motionless bodies soon became surrounded
by a clear space, as if some repelling chemical substance had exuded
from the corpses, and he applied to the phenomenon the fanciful
name of nekrophobia, fear of the dead. The meeting of the sexual
cells, the attraction of food, the senses of taste and of smell are all
cases in which chemotropism plays an important part.

I have given only a few simple instances of these fundamental
reactions of living matter. They occur at first without any of the
‘complicated bodily machinery through which they act in the higher
forms of life. They are not rigid like the actions and reactions
THE PURPOSE OF YOUTH 235

between bodies of matter that are not alive, for the living matter
is constantly changing and almost from moment to moment may
behave differently with regard to the same stimulus. They do
not occur separately and independently, but in all the higher forms
they are combined in varying degrees. But without doubt they
are, so to say, the raw materials or uncombined elements of the
instincts. A new-born mammal pressing against its mother and
seeking the nipple acts through a complicated nervous and muscular
machinery so nicely adapted to its purpose that it can hardly fail
to act. But it acts through various tropisms, the reactions to
warmth, to contact, and to chemical stimulation through taste
and smell.

These various factors of instinct can be modified by experience.
In a few cases the same response is repeated to each application of
the stimulus, but it is far more usual for a change in the response
to take place, the duration of the change increasing in the higher
animals until it passes into what can be called memory. An in-
fusorian animalcule will go on bumping up against an obstacle
indefinitely, at each contact recoiling, twisting over and charging
again, and it is mere luck if in a series of movements of this kind
it finally discovers a way round. A worm similarly confronted
with an obstacle behaves practically in the same way, but it gets
more and more excited in its movements, and may finally get round
by some violent contortion, more or less in the fashion that a man
reading a book will, from time to time,simply put up his hand to
push away a persistent blue-bottle, but at last will get out of his
chair and hunt it round the room. In the latter case, however,
in addition to the summation of the irritating effect of the stimulus,
the higher parts of the man’s brain come into play, and he ceases
to be merely insti.ctive. A fish which was kept in a tank was
accustomed to come to a particular place for a piece of food that
was dropped in. Then a sheet of glass was fixed between the
habitual lurking-place and the spot where the food was dropped.
For some time the fish continued to dart out on the food, bumped
up against the glass, retired and returned to the charge. Presently,
however, it ceased to respond, and, for a few days afterwards, no
longer rushed at the food even although the glass had been removed.
It is the natural instinct of a spider to drop from its web at any
sudden vibration, or when a shadow is thrown on it. Mr. and
Mrs. Peckham, experimenting with spiders, found that they would
drop when a tuning-fork was sounded near them, but that after
236 CHILDHOOD OF ANIMALS

fifteen times they ceased to take any notice of the disturbance.
Even extremely simple creatures which live attached to a surface
by a contractile stem and shrink up to their support when they are
touched soon fail to respond to a repeated stimulus. The infusorian
Vorticella, the polyp Hydra, behave in this way, and a sea-anemone
which at first contracts its tentacles when they are touched will
very quickly cease to respond. So also single-celled creatures
become accustomed to, and may even reverse their response to
weak chemical stimulation ; instead of withdrawing from alcohol,
they may move towards it. When the chemical tropism is a response
to a food substance, it may cease when the animal is satiated, to
be resumed later on, and this may mean no more than a change of
chemical interaction due to the changed condition of the fully fed
organism. When a sea-anemone is fed a certain number of times
in succession with pieces of fish or flesh, it will refuse further pieces,
so that here there must be a transference to the tentacles of the
change produced by the food in the digestive tract. But a more
complicated change in reaction has also been obtained by experi-.
ments on the sea-anemone, for one that was fed repeatedly on
filter-paper soaked in the juice of a crab ejected the paper, and
after some experiments would not even swallow it.

There is no doubt but that the effect of the stimulus can be
inodified or reversed by repetition in all the simpler cases that have
been tried. These results, however, wear off very quickly in the
case of single-celled creatures and the simpler animals, and after
a lapse of time, which may be measured in minutes, hours or days,
the normal responses to the stimulus are resumed. We may sup-
pose the protoplasm and the very simple mechanisms of muscle
and nerve concerned to recover from the fatigue or strain, or
abnormal chemical condition, into which they have been thrown,
and on their recovery to be practically, perhaps completely, un-
altered. It is different, however, with higher animals, where there
seems to be a power of registration of the effects of experience, a
registration that becomes not only more complete but more easily
available in vertebrates than in other animals, and in the higher
vertebrates than in the lower vertebrates. The organic mechanism
itself consists of a simple form of sensitive organ to receive the
stimulation, nerves to transmit the message to a group of nerve-
cells which again directly or indirectly control a group of muscles
to carry out the reaction. This mechanism may be permanently
altered by experience, but, besides such alteration, the results of
THE PURPOSE OF YOUTH 237

experience seem to be stored, so to say, in some separate receptacle.
All physiological knowledge points to part of the grey matter on
the surface of the brain as the storehouse, and it is precisely this
region which becomes relatively larger and more complex in the
higher vertebrates. What we must suppose to happen in those
animals which possess this storehouse of experience is that when
stimulation occurs it calls up or awakens not only the special
mechanisms with which it is connected, but the reservoir of past
experience. The resulting action is controlled not only by the
mechanism, but by the effect on the mechanism of the stored expe-
rience. The name for this storehouse of experience is memory,
so that what happens in the higher animals is that response to
stimulus is increased, controlled or modified by the memory of
past responses. It has to be remembered that memory need not
be conscious. Consciousness is the most difficult idea to transfer
from ourselves to animals, but memory we can observe and make
the subject of experiment. Sometimes the word memory is applied
not only to the separate storing of experience in the reservoir that
we must believe to lie in the grey matter of the brain, but to the
warping of the actual mechanism. There is a distinction in fact
between the two. We can see the more sensitive “ brain memory ”
switched off by operation or disease, or by drugs, or by gusts of
passion that do not reach the mechanism. And we see by keeping
clear the distinction between the two the opportunity for a choice
of response to stimulation; the response may be due chiefly to
mechanism or chiefly to memory, and if chiefly to memory, to one
of several memories. Add consciousness to memory, and you
will find it very difficult to distinguish the simultaneous know-
ledge of several different possible responses from what we know
as free will.

These high problems have taken us far away from instinct.
Although what I believe to be the component parts of the instincts,
the responses to stimulation, can be modified by experience, the
more complicated and typical instincts are not modified by expe-
rience, and, indeed, many of them are called into play only once
in the life of an individual. Nature has chosen another path for
them. They have been built up in the long history of the race
into very perfect mechanisms which admit of no alteration and
of no blundering. Given the appropriate conditions and the result
follows. The animals are fully equipped to meet a certain set of
circumstances, and if these present themselves, the adaptation
238 CHILDHOOD OF ANIMALS

between organism and environment is complete. If the proper
environment does not present itself, the instinct cannot come into
operation, and if it be necessary to the life of the animal, the animal
dies. No doubt instincts vary, like every part of the animal organ-
ism, and in course of time, by a continuous rejection of the less
suitable variations and a continuous preference of the more suitable
variations, an instinct might change. But so far as the individual
is concerned, the instinct is fixed.

The operation of an instinct requires, in proportion to its com-
plexity, a certain complexity of structure, and unti the latter has
been attained it cannot take place. On the other hand, it does
not require practice, and there is no reason why animals that rely
upon instincts should have their period of youth longer than the
time required for bodily growth and development. In the verte-
brates, however, and especially and increasingly so in vertebrates
with high brain development, the rigid instincts are being broken
down and replaced by actions controlled by experience and by
memory, and so fitting more varied circumstances and more varied
environment. The period of youth is prolonged to afford time for
this. The animals are protected and cared for by their parents,
and allowed a space in which the burden of life does not press
heavily upon them, and in this time they have to educate their
instincts, destroy their rigidity, allow them to be controlled by the
stored-up results of experiment. The purpose of youth is to give
time for this, and therefore those animals which are most intelligent,
which have the most complex brains, have the longest period of
youth.
CHAPTER XV
EDUCATION

THERE is no complete separation between instinct and experimental
action. The animals in which instinct rules come into their full
powers at once, and have little or nothing to gain from experience.
But the higher types of animals, those in which experimental action
directed from the experience stored in the brain is the dominating
feature of life, start with certain clearly marked aptitudes or ten-
dencies which may be called instinctive. It is not merely because
a carnivore has teeth and claws that it becomes a beast-of-prey, or
because a duck has webbed feet that it begins to swim. In the
slow process of evolution, the structure of different kinds of mammals
has become so fitted to the kind of life they are going to lead that
it is difficult for their machinery to work, so to speak, in any way
but the way for which it is fitted. And part of the structure is
the unconscious nervous mechanism which lies behind instinct,
and which requires time for growth, but not necessarily time for
training. But however definite may be the direction of apti-
tudes, most of these have to be educated by experiment and teach-
ing, to adapt them to the varying circumstances to which they
must be applied. The animals have to be initiated into life, they
have to learn to use their bodies. The moment a may-fly has freed
itself from its pupal case, it is able to crawl up on a dry bank, and
the moment its wings have expanded under the influence of light
and air, it flies off with as complete control of its powers as it will
ever have during its short life. This is not so with most of the
powers of the higher animals. They have to learn control over
their own body and over their special kind of locomotion. Even
when they are strong and active, young birds and mammals fly
or run against obstacles, lose their balance, fail to stop in time or
to turn quickly, and hurt themselves in many ways. The very flexi-
bility of their powers makes it more difficult to exercise them with-
out practice. They have to acquire skill in obtaining their food, as
well as knowledge of what that food is. To nibble grass, to gnaw
239
240 CHILDHOOD OF ANIMALS

roots, to strip fruit or leaves from trees require a certain amount
of skill, and it is amusing .0 see how clumsily young animals usually
set about these necessary tasks. When the food is a living prey
that runs or jumps or turns on its enemy, even greater knowledge,
skill and agility are required. The young animals have to learn
to defend themselves by recognising danger, by hiding or escaping
by swiftness, or by fighting.

Young birds and mammals differ very much in the difficulty
they seem to have in acquiring their various forms of locomotion.
Ducklings, even if they have been reared under a hen, take to the
water at once and swim without any practice. Cygnets have to
be coaxed or pushed into the water by their parents, and seem
anxious to get out of it, either on the bank or by climbing
on the backs of the adults (see Plate XI). Young gulls
avoid the water for a considerable time, but eventually are
taken to it by their parents. The aquatic mammals, except,
of course, whales, dolphins and porpoises, manatees and
dugongs, are all born on land, and have to be coaxed or driven
into the water by their parents, but as soon as they get there
swim as instinctively as fishes or snakes. So far as I know,
all the quadrupeds are able to swim, partly because the attitude
in the water and the movements of the limbs are not very different
from those to which they are accustomed. Most of them are very
much alarmed at first and would readily drown from the exhaustion
produced by their violent, spasmodic efforts. The fact, however,
that most of them soon become accustomed to water, and swim with
ease for long distances, shows the remarkable difference between
their flexible varied possibilities and the rigid adaptation of lower
animals.

The ancestors of birds were quadrupeds and no doubt walked
on all fours like most living lizards. The front limbs have been
transformed into wings, and birds are now purely bipeds, walking,
hopping or running only on their hind-legs. This form of loco-
motion appears to be more difficult to learn than the quadrupedal
gait of four-legged creatures. Newly hatched chicks take some
hours to learn to walk, even if they are helped by the mother. At
first they shuffle along clumsily, using the wings as crutches. The
wing of a nestling chick has a little claw at the tip of the thumb,
and if a still earlier stage be examined, the tips of the first and
second fingers as well as the thumb are seen to be separate, and
appear as if they were going to develop claws, although they do
+s PLATE XI

BLACK-NECKED SWAN CARRYING
CYGNETS ON HER BACK
 

 

 

 

 
EDUCATION 24r

not actually do so. The nestlings of the common moorhen, of the
porphyrios, and of quite a number of birds that haunt reeds and
water-weeds have a well-developed claw on the thumb, and by
the help of this, use the wing in scrambling over the nest. The
nestling of a peculiar South American bird, the hoatzin or stink-
pheasant, has not only a thumb-claw but a claw on the index finger.
The nests are built high up in trees overhanging the water, and
for some time the little birds crawl over the twigs on all fours like
young reptiles. It is clear that the bipedal gait is a recent acquisi-
tion, and traces of the older form of walking are seen not only in
the structure of young birds, but in the difficulty which they have
in learning to walk.

Little quadrupeds find it easy to walk as soon as their legs are
strong enough to support them. Young kangaroos, when they
begin to come out of the pouch, use their front paws a great deal
in walking, and only gradually acquire the hopping gait of the
adult. Most monkeys are really quadrupeds in gait, and when
they are running fast on the ground, gallop on all fours. Little
monkeys certainly do so, and it is only when they jump up on their
mother or on a branch that they use their hands as hands rather
than as paws. Even when they are climbing trees, the posture
of monkeys is not upright, and all the young chimpanzees and
orangs that I have seen get on all fours when they are moving
quickly. Gibbons run on their hind-legs, with their bodies
erect, but with an uneasy swaying movement, using their long
arms as balancers and holding them ready to give support at any
moment. Human children, of course, begin to crawl on all fours
and learn to walk only with much difficulty and with a good deal
of persuasion and help.

The difficulty which bipeds have in learning to walk is thus due
to a double cause. In the first place the action, like most of the
actions of the higher animals, is not purely an instinct, but the
complex balancings and the varied movements are learned partly
by experience. In the next place, it is a comparatively recent
acquisition of the race, and the structure still contains many
elements which are not yet completely adapted to it.

Learning to fly is a still more difficult task. Young swallows
are said to fly without any teaching or persuasion, and it may be
that these, which are, perhaps, the most completely aerial of birds,
have reached a stage which most birds are only on the way to
reach. In most cases, the mothers have to use persuasion or force,

C.A. Q
242 CHILDHOOD OF ANIMALS

and to protect the fledglings from hurting themselves in their first
efforts. Sparrows may be seen tempting their young into the air
by offering them food and then flying off a little distance before
it has been taken. The mother stork pushes the young birds off
the edge of the nest or chimney-stack on which they have been
resting. Most of the birds-of-prey and many of the perching and’
singing birds push their young off a support and then hurriedly
fly under them to break their fall. Even after the first fluttering
movements have been made, young birds take weeks or months
before they acquire perfect control, before they can turn in the air
alight suddenly on a branch or even on the ground, and certainly
before they can readily launch themselves into the air from the
ground. I have not been able to obtain any information as to
how young bats, flying squirrels and other volant mammals take
to the air. I should expect to find that they learn with difficulty
and that they are aided by their parents.

The process of learning to eat shows an intimate blending of
instinct and experience in both birds and mammals. The instinctive
part resides chiefly in the senses of taste and smell, and the part
that comes by experience is the association of appearance with
edible qualities. But the matter is further complicated by the
fact that many young birds and mammals are fed by their parents
and would otherwise starve in the midst of plenty. In the case
of birds, those that are hatched in an active condition generally
pick up their own food almost at once. At first they peck at every-
thing, taking stones, grains, fragments of vegetation, insects or
pieces of flesh, but very soon select only vegetable matter if they
are eaters of plants, different kinds of material if they are omni-
vorous, or grubs, insects, fish or flesh if they are carnivorous. The
carnivorous young birds do not seem to have any strongly marked
choice between fish and flesh. A good many of the active young
birds are assisted by their parents, either by food being brought
to them, or disgorged in front of them, and these when they are
left to themselves will pick up food, but will die rather than hunt
for it. They learn only slowly that food may be edible even although
it is not brought by the parent. All the birds in the mouths of
which the parents place the food take a very long time to associate
the appearance of food with the idea of eating. If substances are
actually placed in their mouths, they instinctively swallow them,
but reject them if they are unsuitable, and soon learn to do so
without having swallowed them. On the other hand, hungry young
EDUCATION 243

birds, large enough to be able to hop on the branches or even on
the ground, will shriek for food with their bills gaping widely,
although attractive worms are wriggling and squirming within an
inch of their nose and eyes. When they are rather older and have
learned to go in quest of their food, they are still indiscriminate.
Opinions are divided as to how far old and experienced birds eat
the brightly coloured, nasty-tasting caterpillars and insects which
are supposed to warn prospective enemies of their unpalatableness
by their gaudy hues, but it is at least certain that young birds have
no instinctive knowledge of this kind of advertisement, and greedily
eat creatures with which their palates or their stomachs quarrel.
There is much the same set of differences amongst young mam-
mals. The act of suckling seems to be purely instinctive and takes
place as soon as the little creature finds the warm nipple. An
artificial teat arouses the instinctive action nearly as well as the
natural organ, and young mammals take readily to the bottle.
But if the liquid supplied be cold, or very different in flavour from
milk, the reflexes do not work and the material is not swallowed.
When the milk diet begins to be varied with other substances, there
is an interplay of instinct with the results gained by experiment.
The vegetarians will not attempt to nibble flesh or fish or living
animals, but they take some time to learn the difference between
grass and dry paper, and so forth. The sense of smell and that of
taste are certainly present, but act at first only on acute differences
and lead them to reject certain substances rather than to show
preferences amongst those that they will take. When they
are a little older, they begin to select, but the choice they make is
difficult to understand. I have offered green vegetation of different
kinds to many young herbivorous mammals with most conflicting
results. They are attracted by green colour, and I have never
found any that would refuse such palatable and wholesome leaves
as willow, poplar, hawthorn and elm. Young camels, sheep, goats
and deer will take leaves like elder into their mouths, and some of
them will swallow it, whilst others reject it after having tasted it.
Antelopes and cattle are more wary or have a keener sense of smell,
for they generally refuse leaves of elder after smelling them
but before tasting them. Green French beans, of which most
young animals can have no experience, are approached with the
greatest caution and are generally refused until a good deal of
persuasion has been employed, although I cannot perceive that
these vegetables have any appreciable odour. When animals have
244 CHILDHOOD OF ANIMALS

taken them once, and chewed and swallowed them, they recognise
them again and seize them greedily. Green onions, celery and
some other wholesome but strong-smelling leaves most of the
animals to which I have offered them have taken at once. I do
not think that there is any instinctive recognition of or rejection of
poisonous plants; the young animals have good memories, and if
a plant is unpleasant either to the sense of smell or still more to the
palate, it is rejected after trial and not taken again.

Young mammals which naturally would have their. food brought
to them by their parents, seem to have a very small amount of
instinctive selection or rejection, and when they are brought up
by hand will take very unsuitable food. This at least has the
convenience that they are not at all difficult to get to feed when
they are being brought up artificially, and will often live for a time
on very erroneous diet. Many of them that have been treated in this
way acquire unwholesome tastes which are not easy to replace.
Young walruses and polar bears have reached zoological collections
after having been kept alive since their capture on whales’ blubber,
which is certainly an unsatisfactory diet for a growing animal, and
there has been the greatest difficulty in getting them to take fish
or flesh.

Thus even in the simplest and most necessary parts of their
activities, young birds and mammals do not spring fully equipped
into life, but have to learn by trying. They have instincts, but
these carry them only a little way. Few of them can walk or swim
or fly without laborious practice, often aided by help or coercion
from their parents. They have not full control even over their
muscular powers, and there is not a proper adjustment of the co-
ordination between eyesight and movement. They overbalance
themselves, totter, outrun themselves, stumble and bump about,
miscalculating distances, and are blundering creatures in an un-
familiar world, whilst the lower animals take up the game of life
as if they were only renewing it after a sleep. At first sight, the
advantage seems to rest with the animals guided and ruled by
perfected instincts, but we have to remember that they are at the
mercy of the chance of finding the right conditions and the right
stimulations to awaken these instincts. If the conditions are wrong,
the world is not merely strange, but forbidding, hostile, impossible,
and they perish. The higher types, being less accurately adjusted
to any particular environment, can become accustomed to a much
wider range of environment. No conditions are quite right for
EDUCATION 245

them, but they can learn to make shift with almost any conditions
in which they happen to find themselves. It is with this task of
fitting themselves to the world that they occupy their youth, and
it is for this task that they enjoy a prolonged period of youth and
a degree of freedom from the immediate cares of finding their own
livelihood and protecting themselves against the dangers of the
world.

The high spirits of young animals are proverbial. The Latin
song, familiar to university students of the Calvinistic North,
“ Gaudeamus igitur, juvenes dum sumus ’’—“‘ Let us rejoice whilst
we are still young ’’—is at once needlessly defiant and needlessly apolo-
getic. Therandomhigh spirits of youth are as necessary and inevitable
as the serious and restrained pertinacity of maturity. Not only young
human beings, but young apes and monkeys, carnivores and herbi-
vores, rodents and edentates, liberate an excess of vitality in the
wildest antics. But it is to be noticed that this is not true of all
young animals. Caterpillars young cockroaches or grasshoppers,
lobster; or crabs or snails are not to be distinguished from their
seniors by any excessive gaiety. The exuberance of youth begins
with the higher animals and increases as we ascend the scale of
vertebrate life, precisely as parental care, intelligence and relative
duration of youth increase. The high spirits of youth are part of
the new order of things in which the period of youth is devoted
to the replacement of instinctive action by experimental action.

It used to be said that as young animals of these higher types
were fed and protected, they had a surplus of income over output,
and that their high spirits, expressed in games and antics, were
the inevitable result of this surplus vitality. Certainly, if they
were left to themselves, they might have no spare energy, but to
say that their exuberance is the mere discharge of a waste product
is to read very plain facts wrongly. They are fed and protected
in order that they may have surplus energy, and they require the
surplus energy for the experimental business of their youth. They
use their surplus energy in ceaseless experiment with all their powers.
Limbs, claws, nose, teeth, tail, all their senses and organs are
exercised in every possible way, are applied in every possible direc-
tion, on e erything that comes within their reach. They learn to
use their natural powers, they gain experience of their limitations,
and acquire knowledge of the world.

The destructive habits of young animals are by no means specially
marked in predaceous creatures, but are simply a part of the experi-
246 CHILDHOOD OF ANIMALS

mental curiosity of youth. Human children, until they have been
laboriously taught to behave differently, pull to pieces everything
they can get hold of, toys, dolls, implements of all kinds, and even
such live animals as they are able to reach, using their teeth and
fingers in the work of destructive exploration. Young monkeys
behave exactly in the same way. They break all the toys that
are given to them, tear their blankets, pick their bedding to pieces
and scatter it about, spend almost inexhaustible patience in un-
ravelling the wire of their cages, or in trying to open the doors or
break the hinges, and, just like children, they can be taught, up
to a certain point, to handle things more carefully and to refrain
from breaking them in the presence of their keepers. But as soon
as they are left alone, they resume their occupation. Puppies,
the cubs of wolves and foxes, and kittens of every kind, colts, the
fawns of deer and antelopes, calves and kids, and even young
elephants show the same restless exploring energy. There is no
corner of my study that my young hyrax has not thoroughly in-
vestigated, pulling books out of their shelves, nibbling the corners
of papers, pulling about the skins of birds, trying teeth on the tele-
phone receiver and the electric lamp-shades, jumping up against and
trying to push over things out of reach. It has now learned to stop
when I shout ‘“‘No”’ across the room, but at once proceeds to hunt
for a new game. Its greatest delight is to climb on my shoulder
and tug at my tie until it has succeeded in unfastening it. Some
birds, such as parrots and cockatoos, remain mischievous and
destructive all their lives and beguile the tedium of captivity by
pecking and gnawing every object they are able to damage, and
sheet iron seems the only material that beats them; they destroy
the woodwork of their cages, twist and unpick the wire, strip the
bark from every piece of wood, root up every plant, and pull
to pieces and scatter any faggots that are placed to shelter them.
But most birds in their youth have similar instincts, and often
cause their parents much labour in repairing the damage they do
to the nest.

Much of the experimental activity of the young, and especially
that shown in games, is not random, but is defined and directed by
their structure and instincts. Professor Groos has shown that the
games of young animals bear a definite relation to their future life ;
he has extended to other mammals the application of the saying
that the battle of Waterloo was won on the playing fields of Eton.
Animals that have to escape or to catch their prey by swiftness
EDUCATION 247

‘and dexterity rush madly in circles, or race each other until they
have to lie down from exhaustion. Goats, sheep and chamois are
mountainous, rock-loving animals, accustomed to make high vertical
jumps from one ledge to another. Their kids and lambs practise
high jumps with an effect that is ludicrous when we see them on
flat ground suddenly springing into the air. Rocky-mountain
goats are said to be the most sure-footed of all animals; they
are slow and deliberate in their movements, creeping along almost
invisible ledges on the face of precipitous cliffs. Their kids show
the same stealthy and careful movement, climbing to the roof of
their shelter, not by sudden jumps, but almost inch by inch. Gazelles
and antelopes which inhabit open plains practise long jumps when
they are young. Young dogs and wolves run round and round in
circles trying to head each other off. Most of the smaller cats are
accustomed to take almost vertical high jumps; domestic kittens
can be seen to make sudden leaps in the air almost like young goats ;
my tame caracal kitten used to stop suddenly when running, gather
its legs together and make most comical vertical leaps in the air.
Caracals in the wild state prey chiefly on birds, which they stalk
until they flush them, and then leap in the air and catch them on
the wing. I have seen an adult caracal in the Zoological Gardens
stand under a shelf five feet above him, look up at it as if measuring
it with his eye, and then reach it by a straight vertical jump without
arun. Climbing animals, when they are young, practise climbing
assiduously. My tame hyrax, almost day by day, found some new
feat to attempt, and kept trying until it succeeded. One of its
first serious experiments was to climb the smooth leg of an iron
bedstead, which it did at first rather clumsily, choosing after
many vain efforts the leg that stood in a corner, and getting
up by pressing its back against the angle of the wall and its feet
against the iron rod, much in the fashion that a mountain climber
ascends a “‘chimney.’”’ It soon became perfect in this method of
reaching the bed, and then proceeded to acquire the art of swarming
up the more difficult legs where there was no wall to help. The
smooth leg of a mahogany chair was then mastered. The polished
rails of a hot-water towel stand took a longer time, but the little
animal persevered until it had learned to climb the vertical barg
and walk along each of the horizontal bars, and finally to swing
down from one horizontal bar to another. One evening it dis-
covered that it was possible to ascend the vertical moulding that
surrounded a door. The moulding was about four inches across
248 CHILDHOOD OF ANIMALS

and projected an inch and a half from the wall. The hyrax straddled
this, pressing against the projecting edges with the palms of its
fore-paws and the soles of its feet, and got a good way up in a series
of little jumps. Its usual method of descending a pipe was to
turn round and come down head foremost, which was impossible
in this case. It suddenly stopped and shrieked until I came and
helped it down. It then at once made a second attempt, I standing
near ; when it got near the top, it turned round as if to see that
help was at hand, and then slowly slid down backwards, refusing
any assistance. When it found that it was possible to get down
safely, it tried again and again, until at the fifth attempt it reached
the top of the door, where it could turn round and come down in
the way it preferred. A lesson once acquired was never forgotten ;
after finding out how to master a difficulty, the animal never bungled.
Similar observations have been made on many young animals,
but particularly in domestic animals. In the case of the hyrax
there was no possible taint of ancestral modification by domestica-
tion, as its ancestors from time immemorial had lived in the high
tree-tops of Nigeria. I have said a good deal about it not merely
because it was an engaging and unfamiliar pet, belonging to a group
of mammals of which we do not know much, but because it shows
admirably the fundamental difference between the instinctive and
the experimental types of action, and the great advantage that
those animals enjoy which have the power of fitting their natural
capacities to any strange environment in which they may come to
be placed.

The games of young carnivores have a direct bearing on the
catching of a living prey. A kitten’s play with a reel, patting it,
making it roll to a distance and then springing on it, like the game
of the mother with a real mouse, is a method of training the eye
and muscles for the important business of catching dinner. The
natural instinct for such games is inborn, but the capacities have
to be trained. The mother of wild carnivores gives her kittens
or cubs the tip of her tail as a toy, making it quiver to attract their
attention, flicking it away from them and tempting them to spring
on it. My caracal kitten, which had been removed from its mother
long before it was old enough to play, amused itself with a reel and
a ball exactly like a domestic kitten. When it was being played
with, it used to bring back the ball and lay it down to be thrown,
but it invented a game of its own. There is a rather long corridor
in my house where it was possible to have a very good game of ball.
EDUCATION 249

At first the caracal used to bring the ball back to one end of the
corridor and chased it as soon as it was rolled along, in a few days
learning not to dash up against the wall at the end, if it had not
previously captured the elusive prey. But it tired of this, and,
having brought back the ball, it would dash half-way down and
lurk in one of the doorways where it could not see the ball except
for the moment it flashed by, and the game was not to run after
it, but to intercept it as it passed.

Many of the games of young animals are preparations for fighting.
Kids, lambs and calves butt and engage in endless mimic combats.
Deer stand up on their hind-legs and ‘fight with their fore-legs.
Young donkeys, horses and zebras dash at one another, rearing
and striking with their heads and fore-legs. All the young carni-
vores romp and tussle with each other. Puppies try to seize their
friendly enemy by the throat, to roll it over and to hold it down;
the vanquished animal lies on its back and strikes ou twith its fore-
paws. Young lions, tigers, cats of all kinds and young bears
wrestle and struggle with each other, sometimes biting rather
severely. My caracal was extremely fond of fighting in a playful
way. He used to bring to me a felt slipper and invite me to take
it from him, when a wild romp with teeth and paws followed ; he
tried hard to remember not to bite me, but in the excitement of
the struggle sometimes forgot or misjudged. His favourite attitude
of defence was to lie on his back, holding the slipper in his teeth,
and ready to strike out with all his claws; he soon learned to be
a good deal quicker than I was, and if he got into his most favourable
position, I could not get the slipper without some risk. But it
was only a game, and when it was over, the ears came forward to
their normal position, the muscles were relaxed, the claws sheathed,
and the little fiend became again a gentle pet. When young carni-
vores are playing too roughly with their mother, she teaches them
a lesson by cuffing them, but I have never seen her interfering to
stop a quarrel in her family, and not infrequently a good deal of
damage is done as the excitement of the game passes over into
reality. Many years ago, I saw by accident a fatal fight between
a young lion and tiger of about the same weight and age. Two
tiger cubs and a lion had been brought up together in the same
compartment of the Lion House and were a little over two years
old, and thoroughly accustomed to rough but friendly play.
One Sunday morning, however, when I think I was the oniy
visitor in the Lion House, I heard a sudden commotion and ran to
250 CHILDHOOD OF ANIMALS

see what was happening. The tiger (it was a tigress) had seized
the lion by the throat and was holding him down. The other tiger
walked round and round the couple, apparently not much interested,
but every time it passed the outstretched tail of the lion it stooped
down, and bit it in a casual and rather bored way. Before the
keeper could separate the animals the lion was strangled. I do
not know what was the cause of the dispute, but mimic fights often
become serious. When young animals are beginning to take
pleasure in their strength, it is important that they should have
plenty of room and a diversified open space in which to run about.
They then work off much of their surplus energy in chasing each
other, and are less disposed to fight to a finish. But even under
natural conditions, usually one or two of the weaker cubs are killed
in these experimental trials of strength.

Perhaps the most interesting and distinctive feature of the higher
animals when they are young is their faculty of attention. In
the drawing of the Springbuck shown on the plate (XII) the
artist has caught a very characteristic attitude of attention. Adult
animals are alert and watchful. A sudden sound, a moving object,
a vibration of the soil or the surface on which they are placed at
once arrest their attention. They stop chewing or drinking, even
if they are hungry or thirsty, cock their ears, turn their eyes in the
direction from which the disturbance seems to be coming, and you
see that every sense is on the alert. Then some process takes place
which if it were in a human being we should associate with memory
and judgment. The disturbance is recognised as something not
worth troubling about, and the occupation is resumed, or it is
followed by some action, of retreat or of preparation for aggression.
These successive actions take place whether they are accompanied
by some dim mental phase corresponding in a faint way to our
conscious judgment, or whether they are like the unconscious action
of a sleep-walker. Adult animals generally decide at once as to
whether an event which has engaged their attention is of a kind
to neglect or of a kind requiring action. They do not show much
curiosity, but, right or wrong, abide by their decision and proceed
with the business in hand. They have stored up enough experience
and have no special wish to learn anything new. Young animals,
on the other hand, are intensely curious, and the process by which
they fit themselves to their environment can be watched. My
hyrax was at first much disturbed by the sound of a clock in
my room, which chimes the quarters and strikes the hours. At
PLATE XII

GROUP OF SPRINGBUCK AND
YOUNG

Drawn from examples living in the London Zoological

Gardens a few hours after a kid was born. The adults

showed the characteristic attitude of attention as they
faced the artist.
 

 
EDUCATION 251

first it would stop whatever it was doing when the sound began;
letting even a piece of its favourite ice-wafer drop from its mouth ;
then it became accustomed to the sound and now just stops for
a second and resumes at once. I have tried it with other striking
clocks, and it seems to have classified all of them as harmless.
With the telephone bell it acts differently, rushing across the room
to the telephone table, climbing up to the instrument and waiting
there for me. I have tried it with an alarm clock, the sound of
which is much like that of a telephone bell, and it at once accepted
that as one of the things to be run to. So also the sound of passing
motors, of persons talking in the adjoining room, were noted,
acquired and put into categories.

Curiosity, attention and memory do much for the education of
young animals, but the very strange faculty of imitation also plays
its part. I do not know of any term used of animals that is
more difficult to understand or to apply justly. The chief difficulty
is that we are disposed to interpret the actions of animals too much
in the same fashion as those of human beings, and to suppose the
presence of a conscious factor which may not exist. When we
speak of imitation in human beings, we think of the imitator as
forming an idea of the action, and of that idea suggesting corre-
sponding action on his own account. It would be going very far
indeed to assert such a mental process in the case of animals. Many
cases that are sometimes set down to imitation are no more than
instances of similar vital machines responding in the same way to
the same stimulus. A kitten washes itself or plays with a ball
precisely in the same fashion whether it has been brought up
by its mother with its brothers and sisters, or has been reared
pray from all other: cats. Animals left to themselves gain the
same lessons from the same experiences that they would have learnt
in association with their kind. I do not doubt but that my hyrax
climbs at least as well as if it had been running with its mother in
the tree-tops. The fact that so many young animals follow their
mother accounts for many of the circumstances that look like imita-
tion. When she runs, they run after her, and it is only by experience
that they learn to associate with running the stimulus that made
the mother run. They run, not because they are imitating her
action, but because itis their habit to run after her. So also when
she leads them to the proper food, and they follow her example
by eating it, all that it is necessary to suppose has happened is
that the food stimulus to which they have been led excites them
252 CHILDHOOD OF ANIMALS

to the same action as it excites their mother. Nor does the common
action of gregarious animals really imply imitation. The flayful
stampedes of cattle, the game of “‘ follow my leader ’’ indulged in
by sheep and goats and antelopes, the migrations of mammals and
birds do not necessarily mean more than similar response to similar
stimulation.

Nevertheless there are many facts which make it difficult to
doubt that the higher animals, especially when they are young,
perform actions, consciously or unconsciously, because they have
just been performed by other animals or by human beings. I do
not think that this happens whilst the young creatures are quite
infantile, but only after the period which is well described as ‘‘ begin-
ning to take notice.’ The action must be more or less like one
that the animal would naturally do, or if it be complicated, it must
be built up step by step out of separate actions which are not too
unfamiliar or incongruous with’ natural habits. I picture, rather
than explain, the process to myself by supposing that in animals
with well-developed grey matter in the brain actions write some
sort of record of themselves in the brain, apart from the necessary
reflex brain-and-muscle mechanism by which they are controlled.
This record can be excited in various ways, and its excitement may
set going the actual mechanism. When the young animal’s atten-
tion and curiosity are aroused by the action of another animal,
the records already stored in its brain are awakened, and the most
closely corresponding reflex mechanisms are “called up’’ and set
going. Consciousness is not necessarily involved, but the process
is a result of organic memory.

However it be explained, action which is the result of a corre-
sponding action becomes increasingly important in the higher
animals. Wild animals acquire or at least perfect many of their
capacities in this way. The process of taming and training animals
is based on it. How far birds learn from one another or from their
elders I do not know, and it is a much disputed question. It seems
to be fairly certain that building of nests does not come about by
any process that may be called imitation, and that birds reared
by hand or away from their allies will in due course build according
to the pattern of their kind, although their first attempts may not
be so good as later efforts. The ordinary call-notes and narrow
range of voice that occur in most of the families of birds are similarly
inborn, but the higher and more complicated kinds of song certainly
owe much to practice and emulation. Singing birds that are reared
EDUCATION 253

away from their kind achieve only a feeble and halting song, but
rapidly acquire elaboration and richness when they hear others
singing. There is a kind of local tradition of song, and now and
again you will find a wood resonant, season after season, with
songsters of a more mellowed sweetness, due to the example of
some genius amongst them. Our own intell gence is so remote
from that of birds that we come into little organic contact with
them, and I doubt if birds ever imitate human beings except in
sound, and it is certainly ridiculous to suppose that the cleverest
talking birds have any consciousness of the occasional appropriate-
ness of their remarks.

With mammals we own kinship in every fibre of our bodies and
we can establish 1elations with them in many different ways. Their
senses of smell, taste, touch, sight and hearing, their muscular
movements and reflexes, their passions and their pleasures, the
instincts with which they start life and their mode of modifying
them, are all like our own. This very similarity makes it difficult
not to confuse between real imitation and corresponding action
in corresponding circumstances. There seems no conceivable
doubt about imitation, however, in the case of man and the great
apes. Chimpanzees and orangs watch what is happening round
about them. If you take a wooden match-box out of your pocket
and open and shut it, and then give it to one of them, it will try
to repeat the movement. They copy their keeper in sweeping out
their cage. They are taught many kinds of tricks and perform-
ances almost as much by doing the various motions required in
front of them as by actually guiding them. They will run when
you run, danc when you dance, shoot out their lips and scream
when you set them the example. No doubt there is a pitfall even
here. Monkeys are, as it were, caricatures of human beings; in
a sense they ape man, although they may never have seen him. I
am convinced however, that they constantly perform new actions
because similar action have been carried out in their sight, and
I find it difficult to avoid the belief that the anthropoid apes at
least have some dim consciousness of what they are about. Not-

withstanding the innumerable anecdotes about the intelligence
of other mammals, and the great difficulty there is in describing
or even thinking over one’s own personal experience in taming
and training animals without slipping into language that implies
conscious imitation, I do not think that there is any real evidence
for it outside the group of monkeys. Curiosity, attention and
254 CHILDHOOD OF ANIMALS

organic memory seem to me to account for all the facts, and it
must be remembered that even the word curiosity is a dubious
term. It may mean no more than that the senses are alert to any
stimulation, and that stimulation is followed by action directed
towards the source of the stimulus.

This may seem a doubtful end to an argument, and a cold con-
clusion for one who is a lover of animals. The trouble lies in the
word consciousness. In my opinion instincts, experimental action,
experience, memory with its consequence—choice of motives for
action, the immediate and the remembered—states of pleasure
and pain, all may precede consciousness. Consciousness is some-
thing apart from them, different from them, probably dimly begin-
ning in the lower animals, a little clearer in the apes, still clearer
in savages, but even in ourselves intermittent, and at its best much
less complete than we think.

If, however, we remember that the terms we employ must gain
or lose colour and change their significance according to the extent
to which we are willing to suppose consciousness involved, then
there is no doubt about the facts. The reason why the higher
animals have a long period of youth is that instinctive action may
be replaced by action based on experience, upon the remembered
results of experiment. For this purpose they are fed and protected,
freed from the cares of the world and shielded from its troubles,
dowered with an excess of energy and a fund of high spirits. When
adult, independent life is reached, there is seldom time for reflection
or experiment. The business of life is to meet a continuous series
of emergencies by prompt and unhesitating action, and this is
accomplished best by those animals that have had the longest
youth, the best opportunity for playing at life whilst it was still a
game, and for making mistakes when mistakes mattered least.

The mental field of youth and especially of our own youth is
sometimes spoken of as a tabula rasa, a clean sheet upon which
anything may be written. Nothing is further from the truth. In
young animals and in ourselves it is a blend of all sorts of inherited
instincts and aptitudes, and we have gained the tremendous advan-
tage over other animals and over the lower members of our own
race, that we have a prolonged time for finding out and developing
the aptitudes and for modifying the instincts. O r own youth
should be devoted to this natural purpose. What is called technical
education, the training for a special avocation, the development
of an aptitude for a special calling, should be put off as long as
EDUCATION 255

possible. The infant prodigy, and the youth who quickly finds out
one thing that interests him and plods successfully at it, represent
lower and older types, grades in the evolution of man which are
being discarded. Youth should be spent in blunting every instinct,
in awakening and stimulating every curiosity, in the gayest roving,
in the wildest experiment. Education should be a parade of all
handicrafts, of all mental and emotional stimulations, of the arts
and sciences, and the last thing to be considered is what is practically
useful. The supreme duty of youth is to try all things, to experi-
ment with everything, to be scatter-brained rather than con-
centrated. In due time the world will certainly close round and
press each beginner of life in one direction, but he will meet the
pressure most successfully who has remained young longest and
who has stored up the most varied experience.
INDEX

ADAPTATIONS, 105, 155
Adder, 2, 146
Advertisement, coloration as, 72
Affection, origin of, 131
Afterbirth, 166
Agoraphobia, 234
Agouti, 220
Albatross, 104
Albumin in milk, 185
Alcohol, 186, 234, 236
Alligator, 144, 196
Alpaca, 46, 93, 218
Alytes, brood-care, 141
Amblystoma, 60
Ameeba, 5, 233
Amphiuma, breeding habits, 140
Anaconda, 197
Ancestral and adaptive characters, 8, 16,
223
Andrena, 33
Angler, marbled, nesting habits, 137
Aniline dyes, 112
Animalcula, tropisms of, 234, 235
Anteaters, 163, 178, 220
Antelopes, 46, 75, 115, 170, 171, 219
American, 91
angas, gI
striped, 78
tragelaphine, 89
coloration, 88
rump patches, 71
sexual coloration, 69
skin glands, 184
Antennarius marmoratus, 137
Anthophora, 33
Antlers of deer, 12, 46
Ants, 73, 128, 132, 205
CA.

Ants, white, 125
Anura, 18
Apes, consciousness, 253
milk of, 188
tricks of, 253
anthropoid, 38, 39, 148, 165
Aphides, 133
Appetite, 193
Apteryx, 104, 153
Aquarium, 233
Aristotle, 137
Armadillo, 81, 179, 220
Armour of extinct mammals, 81
Arrau-turtle, 143
Arthropods, 30
Ascidian, 20
Ash of milk and flesh, 186
Aspredo, 138
Asses, 45, 75, 95, 172, 217
Attention, 202, 250
Auk, 149, 154
Automatism, 6, 228, 229
Avocet, 102
Axis deer, 92
Axolotl, 60

BABIRUSSA, 93

Baboons, longevity, 39
Background, patterns matching, 78
Bacteria as external parasites, 82
Bactrian camel, 93

Badgers, 42, 79, 87, 169
Bandicoot, 129

Banteng, 88

Barasingha deer, 92

Barbets, 153

Barley-water for diluting milk, 191

257 K
258

Basket-work, 151

Bates, H. W., 73

Batrachians, 15, 48, 51, 59, 60, 70, 140

Bears, 10, 42, 86, 194
Polar, 168, 169, 243

Beaver, 46, 176, 177, 220

Bee-eater, 153

Bees, 33; 55, 72) 73, 127, 132, 205

Beetles, 33, 70, 128

Beisa, 89

Berries of lobster, 121

Binturong, 85

Bipinnaria larva, 23

Birds,
ancestors, 159, 240
brood-care, 147
domesticated, 204
down of, 97, Iot
duration of youth, 49
eggs of, 147
feeding young, 242
imitation by, 252
insectivorous, 72, 161
intelligence, 50
learning to walk, 240
limitation of family, 148
longevity, 49
patterns, 79
preen-gland, 184
sexual coloration, 69
size and longevity, 49
skin glands, 184
talking, 253

Birds-of-paradise, 49, 62, 66, 69, 109

Birds-of-prey, 49, 105, 110, 150, 152, 153,

154, 242

Bison, 46, 115

Bitterling, 138

Bittern, 153

Bivium, 119

Blenny, 138

Blood, 63, 156, 214, 225

Blow-fly, 31

Blubber, 243

Blunt, Captain E., 56

Boa, 146

Bonavia, Dr., 81

Bongo, gt

Bontebok, 88

INDEX Be, a

Bottle-feeding, 243
Bow-fin, 136
Brain, convolutions of, 226
development of, 226, 227
grey matter, 226
and imitation, 252
of Primates, figured, 227
as storehouse of experience, 237
structure of, 226
and duration of youth, 41
Brain-growth in youth, 229
Breeding plumage, 79, 112
Breeding season, colours of, 69, 113
Bristle-tail, 33
Brittle-star, 120
Brocket-deer, 92
Brood-care, 120
in birds, 145, 159
in frogs and toads, 140
in mammals, 163
in rodents, 176
in spiders, 122
in lower vertebrates, 134
Brood-pouches, 121
Brush turkey, 97, 102, 107, 150, 159, 194
Budgett, J. S., 135
Buffalo, 170
Bufo, 170
Bugs, 70, 82
Bullhead, 136
Bustard, 101, 154
Butter, 186
Butterfish, 135
Butterflies, 55, 70, 73, 118
Button quails, 70, 109, 154

CatveEs of ruminants, 171
Camel, 11, 46, 93, 171, 218
Campodeiform larva, 33, 55
Canary, 205
Cane-sugar, 186
Cannibal larve, 132
Captivity, effects of, 207, 220
Capybara, 175, 220
Caracal, 10, 41, 85

tame, 42, 213, 230, 247, 248, 249
Care, parental, 118, 168, 245
Cariama, 154
Carnivores, boxing of, 233
INDEX

Carnivores, breeding, 41, 166
characters, 42
domesticated, 204
cubs, 169
games, 228
habits at night, 213
handling of, 219
size and intelligence, 43
milk, 188, 190
nervousness of, 213
sexual coloration, 69
taming of, 210, 211
young, 10
and ungulates, 173
vegetarian, 169

Carp, 205

Cassowary, 70, IOI, 106, 109, 149, 154, 161

Castor-oil, 194

Caterpillars, 3, 32, 75, 76, 127, 224, 230

Cat-fish, 137

Cats, 10, 41, 84, 231

Cattle, 46, 88, 171, 219

Cells, of brain, 226, 227
in embryology, 223
as units of structure, 65

Cerebrum, 231

Cereopsis, 106

Chameleon, viviparous, 145

Chamois, 88, 171

Chauna, 104

Cheetah, 85

Chemistry compared with vital func-

tions, 232

Chemotropism, 234

Chevrotain, 93

Chicks, precocious, 101

Childhood, definition of, 1
summary of characters, 222

Chimpanzee, ancestor of, 7
fear of snakes, 201
gait of, 241
and imitation, 253
longevity, 38
performing, 209
taming of, 208
trained, 221

Chrysalid, 3, 32

Cicada, seventeen-year, 56

Cichlids, brood-care, 138

259

Circus-performing elephants, 44
Civets, 10, 85
Civilisation of ants, 132
Cladocera, brood-care, 120
Claustrophobia, 234
Claws of young carnivores, 212
Cleanliness, in apes, 210
of carnivores, 211
of hyrax, 216
of nests, 161
of ungulates, 216
Cliff-swallow, nest of, 151
Coal-tar, 112
Coati, 87
Cockatoo, 199
Cockroach, 34, 124, 205, 233
Cocoon, 122, 124, 130
Cod, 117, 134
Ceecilian, 140
Cold, effect of, 162, 168
Colies, 153
Colonies, of ants, 132
birds, 152
termites, 125
Coloration, definition of, 63
summary of, 68, 112
of birds, 103, 113
concealing, 74, 104, 114
of deer, 72
of down, 104
of eggs, 154, 155
of mammals, 81
protective, 78, 224
sexual, 70
warning, 72, 74, 75
Colour, 62, 66, 67, 112
Communities, of ants, 128, 132
bees, 132
social insects, 132
termites, 125, 132
wasps, 132
Companionship, loss of, 67
animals, 168, 211
Concealment by coloration, 78, 96, 114
Condor, 49, 105, 108
Coney, 95, 216
Consciousness, 233, 237, 251-253
Conspicuousness, 69
Contour-feathers, 97, 98
260

Control, power of, 239, 243
Convolution of brain, 225
Coots, 104

Cormorants, 102, 103, 153, 162
Countershading, 75-78, 88, 97
Coursers, 154

Cowbirds, 148, 157, 190

Coypu, 178

Crabs, 30, 121

Cranes, I01, 154

Crayfish, 15

Cream, 186

Crocodiles, 15, 144, 145, 184, 166
Crows, 150

Crustaceans, 27, 30, 34, 118, 120
Cubs, 10, 168, 190

Cuckoo, 102, r11, 149, 153, 1545 157
Cud, 188

Curassow, 153

Curd, 188

Curel, F. de, 231

Curiosity, 250, 253

Curlew, 102

Cygnet, 240

Darwin, 36, 70, 72, 113, 115
Dassie, 44, 173
Dasyure, 96
Death and young animals, 116
Death-rate of sparrows and human
beings, 116
Deer, 75, 77
antler-growth in, 12
coloration, 91
duration of youth, 46
milk for, 190
rump patches, 71
sexual colours, 69
skin glands, 184
spotted, 78
tameness of young, 219
young, 171
Demersal eggs, 135
Deniker, J.,9
“ Descent of Man,” 70
Desert animals, 77
Development, embryological, of indi-
viduals, 223
Devil, Tasmanian, 180, 220

INDEX

Diatoms, 232
Digestion, 183, 198
Dik-dik antelope, 89
Dipleurula larva, 23
Display of cock pheasants, 71
Divers, 102, 154
Dog-fish, 138
Dogs, coloration, 86
duration of youth, 42
habits of young, 247
qualities of, 205
skin glands, 184
Dolphins, 240
Domestic animals, 48, 75, 204
Domestication, 204, 205, 221
Doves, 111
Down feathers, 97, 98, 101-105, 159
Dragonflies, 56, 70, 125
Drakes, 69, 109
Dromedary, 11, 93
Duck-billed mole, 163
Ducklings, 102, 161, 240
Ducks, coloration of young, 104, 106
colour of eggs, 153
fledging of, 108
longevity of, 49
plumages of, 98, 100, 103, 109
South American, 112
Duckweed, 161
Dugong, 240
Duikers, 46, 88, 89
Duration of youth, 37, 49, 54, 112

EAGLES, 49, 102, 103, 105

Earthworm, 120

Earwig, 34, 124

Eat, learning to, 242

Echidna, 2

Echinoderms, 22, 23

Eclectus, 64, IOI, 111

“ Eclipse” plumage, 99, 100, I10, 112

Edentates, 220

Education, 37, 48, 169, 239, 255

Eels, 53, 54; 233

Egg-cell, 222

Eggs, of birds, colours, 153, 154
incubation, ror
laying of, 148, 149
shapes of, 152
1

INDEX 261

Eggs, butterflies, 129
fish, 52, 115, 130, 134, 138
mammals, 163
marine animals, 117
reptiles, 142, 145, 163
Elands, 46, 90, 219
Elasmobranch, 138
Eld’s deer, g2
Elephants, breeding, 115, 173
domestication, 216
duration of youth, 43
intelligence, 44
size and weight, 43
skin gland, 184
taming, 216
training, 44
young, II, 95
Elephant-seal, 194, 214
Elk, 46, 92
Embryology, 222
Embryos, 129, 139, 142, 163, 224
Emotions, 182
Emu, 101, 105, 149, 154, 161, 182
Endowment, natural, 229
Environment, 223, 238
Evolution, 36, 222, 223, 239
Excretion, 67, 113, 161
Experience, 235-237, 239, 242, 245

Famizy, limitation of, 115, 118, 131, 134,
142, 148
Fantang, 136
Fascination by snakes, 202
Fatigue, 230
Fat in milk, 186
Fawns, 219
Fear, of man, 214
of snakes, 200
Feathers, 83, 97, 98
Feeding, artificial, 190
by spoon, 189
of reptiles, 197
of young animals, 188
Feeding-bottles, 189
Females with male plumage, 70, 109
Ferrets, 169
Fieldmouse, 175
Fight, lion and tiger, 249
Fighting of young animals, 249

Finches, food of young, 161
nests of, 156
Fish, ancestral history, 21
annual rings, 52
brood-care, 139
contact reactions, 233
development of, 222
eggs of, 52
fertility, 134
instincts modified by brood -care, 139
mucous glands of, 184
rate of growth, 51
sexual coloration, 70
temperature of, 50
typical shape of, 21
Fish-lice, brood-care, 120
Flamingo, 49, 104, 111, 151, 153
Flat-fish, metamorphosis, 21
Fleas as parasites, 82
Flies, green, 54
Flight of birds, 97, 242
Fly, 31, 55
Fly-catcher, 111
Foals, 94, 172
Feetus, 9
Fontainebleau, 205
Food, 48, 161, 183, 188, 194, 236, 239, 242
Forest animals, 77
Fossils, 64
Fowls, 69, 107, 108, 222
Fox, 86
Freewill, 237
Freiburg, University of, 60
Frigate-birds, 153
Frog-mouth, 153
Frogs, 15, 17, 51, 59, 75, 140, 184, 231
Fruit-pigeon, 111
Fur, 83
Fur-seal, 42

Gauay, C. J., 56

Gall-flies, 127

Gall-midges, 59

Game-birds, ro1, 103, 106, I12, 153
Games of young animals, 246
Gannets, 102, 116

Garden-spider, 122

Gayal, 88

Gazelles, 89, 219, 247
262

Geese, coloration of young, 104, 106
colour of egg, 153
fledging of, 108
longevity, 49
Genets, 85
Gharial, 144
Gibbons, 38, 201, 209
Gills, 17, 19
Giraffe, 4, 11, 46, QI, 171
Glands, mammary, 183, 185
sebaceous, 185
skin glands in different animals, 184
sweat, 185
Glochidium, 129
Glutton, 87
Gnu, 88, 219
Goats, 75, 88, 170, 219, 247
Goat-sucker, 169
Goldfish, 205
Gorilla, 7, 8, 38, 40, 207, 208
Grades of coloration, 69
Grape-sugar, 186 '
Grasshopper, 124
Grass-snake, 184
Grebes, 102, 106, 153, 160
Green, attraction of young mammals for,
243
Green-fly, 54
Green plants, food of, 183
Gregarious animals, 71
Gregariousness, 145, 177, 207, 252
Greyhound, duration of youth, 42
Grey matter of brain, 229, 237
Grilse, 53
Grizzly bear, moult of, 86
Groos, Professor, 246
Ground-parrot, nest, 149
Growth-patterns, 65, 105
Growth, rate of, 47, 48, 223
Grubs, 127, 128
Guemal deer, coloration, gz
Guillemots, colour of eggs, 154
Guinea-pigs, 46, 176
Gulf Stream, 137
Gulls, coloration of young, 102, 107
colour of eggs, 154
food of young, 162
learning to swim, 240
longevity of, 49

INDEX

Gymunarchus niloticus, 136

HAGENBECK, Carl, 101, 212
Hag-fish, secretion of mucus, 184
Hair of immature animals, 81
Hammerkop, 150
Hamsters, 176
Hand-feeding, 189
Handling of young animals, 219
Hare, 3, 46, 75, 77, 78, 176, 178
Hartebeeste, 88
Harvest-mouse, 176
Hawfinch, nest of, 150
Hawks, young, 102, 103
Heat, radiation of, 67
Hedgehog, 175, 220
Hemipode, plumage of female, 109
Hen pheasants, plumage of, 108
Herbivores, milk of, 187
Herons, 150
Herring, 117, 135, 222
Hessian-fly, 59
Heterotis niloticus, nesting habits, 136
Hibernation of polar bear, 168
Hippocampus, brood-pouch figured, 137
Hippopotamus, 11, 45, 93, 171, 172, 175
218
Hoatzin, 241
Hog-deer, 92
Hog, pygmy, 93
Hoopoo, 149, 154
Hornbill, 103, 149, 151, 153, 158
Horns, 12, 13
Horses, 45, 81, 93, 95, 172) 184, 190, 217
Huanaco, 93, 218
Hudson, W. H., 148
Human death-rate, 116
Human race, 182
Humming-bird, 49, 103
Hunger, 168, 188
Hunting-spider, 122
Hyznas, 10, 86
Hydra, 232, 236
Ayla, 140, 142
Hyrax, 173, 184
tame, 44, 216, 241, 247, 250, 251

IBis, 110, 154
Ichneumon-flies, 127
INDEX

[chneumons, 85
[mitation, 251-253
[ucubation, 101, 145, 156-158
Insectivora, 175, 220
Insects, 31, 34, 54, 55 58, 123, 233
(Instincts, 55, 131, 152, 166, 221, 229-239,
242, 243, 254
Institution, Royal, 199, 200
Intellect, 182
{ntelligence, and duration of youth, 41
and instinct, 229
of birds, 50
of insects, 55
Intestines, 187
Invertebrates, temperature of, 50

JACAMAR, 153
Jackal, 86
Jaguar, 10, 41, 75, 78, 81, 85
Japanese ape, 39, 165
deer, 92
Jardin des Plantes, 60
Jelly-fish, 118
Judgment, 250
Jungle-fowl, 106

KaKaPo, 149

Kaleidoscope, 64

Kangaroo, 3, 46, 75, 77, 164, 179, 241
Kephir, 186

* Khaki,” 78

Kingfishers, 100, 102, 103, III, 149, 153
King-penguin, 110

Kittens, 3, 190

Klipspringer, 89

Koala, 181

Kob, 89

Kumiss, 186

LANDSNAILS, 130

Langur monkey, 165

Lapwing, 99

Lark, 103

Larve, 17, 18, 19, 36, 117, 224
of ascidian, 19
of blow-fly, 31
campodeiform, 55
echinoderm, 22
of eels, 53

263

Larve, of fish, 52

of mussel, 129
Lavatory, chimpanzee and, 210
Leaf-insect, 124
Leaves chosen by mammals, 243
Leeches, 120
Lemmings, 178
Lemurs, 83, 166, 167, 184, 200
Leopards, 10, 41, 75, 78, 81, 85, 213
Leptocephali, 53
Lice, 82
Life, family, in invertebrates, 132
Light, 77, 232
Limitation of families, 118
Limpet, 130
Linsang, 85
Lion, 10, 41, 62, 75, 84, 85, 166, 249
Litter, 193
Lizards, 15, 75

breeding, 145

food, 72, 195

sexual coloration, 70

skin glands, 184

viviparous, 145
Llama, 46, 93, 218
Loach, 130
Lobster, 121
Locomotion, 239
Locust, 35, 124
London, birds in the parks, 207
Longevity and duration of youth, 40
Lumpsucker, 135
Lungfish, 17, 67, 13
Lynx, 10, 41, 84, 85

MACAQUES, 39

Mackerel, 117

Madness, 228

Mammals, armour of extinct, 81
birth of, 165
brood-care, 163
coloration, 97
compared with birds, 49
duration of youth, 37
geological age of, 163
learning to feed, 243
moult of, 82
patterns of, 96
size of, 47
264

Mammals, skin glands, 184
summary of relations to young, 182
weaning of, 191

Mammary glands, 183

Mammoth, 11

Manatees, 240

Mandrills, 39

Mansbridge, keeper at Zoological Gar-

dens, 209

Mantis, 124

Mares, milk of, 186

Marmosets, 166

Marsupials, 2, 179, 182
coloration, 95
duration of youth, 46
eggs of, 163
low intelligence of, 220

Marsupium, 2, 179

Marten, 42

Martin, 161

Mastiff, 42

Mayflies, 55, 125

Meals, intervals between, 188

Meat, raw, use of, 191

Medicine, administration of, 189

Megapodes, 150, 159

Memory, 221, 237, 250, 252

Menageries, wild animals in, 205

Mendel, 74

Mental capacity and duration of youth,

41
qualities, 229

Metamorphosis, 17, 18, 19, 59, 60

Metchnikoff, Professor E., g, 58, 229

Mice, 47, 176, 178

Microbes, 234

Microscope, 117

Migrations, 177

Milk, 166, 185, 186, 187, 188, 190, 191

Milk-glands, 183

Milk-sugar, 186

Mimicry, 73, 74

Mind, 229

Mink, 87

Minnow, 130

Mirror and pattern, 64

Model to show countershading, 77

Models in mimicry, 73, 74

Mole, 175

INDEX

Mole, duck-billed, 163
Mole-cricket, 125
Molluscs, 26, 118, 129, 130
Molobrus, 148
Monkeys, and domestication, 204
as caricatures of human beings, 253
as egg-stealers, 148
coloration of young, 83
diet of, 192
distinctive habits, 246
fear of snakes, 200
fur of young, 83
gait of, 241
milk for, 190
milk of, 188
mode of handling, 210
moult, 83
sexual colours, 69
Moorhen, 104, 241
Mortality of young, 224
Mosaic, body as, 68
Moths, 31, 55, 70, 73, 75, 153
Moulds, 82
Moult, of birds, 98-103, 108
in birds and mammals, 83
and coloration, 69
of down, 107
of mammals, 82, 84, 86, 87, 88, 96
and plumage change, 99
of quills, 98
of spiders, 122
Mouse-deer, 93
Mucus, secretion of, 184
Mule-deer, 92
Miiller, F., 73
Mungoose, 85
Muntjac, g2
Muscle-nerve, 236
Museum, British, 56, 102
Musk-deer, 92
Mussel, 129
Mynah, 199
Mysis larva, 29

Naturat selection, 113
Nature, absence of purpose, 63
prodigality of, 224
Nauplius figured, 29
Nekrophobia, 234
Nestlings, 14, 101-103, 159, 160, 241
Nests, of birds, 101, 149-152, 158
fishes, 135
mammals, 176
spiders, 122
Newts, 2, 15, 17, 70, 184
Night, effect on carnivores, 213
Nightjars, 154
Nilgai, 91
Nipple, 189, 242
Nototvema, 142

OIL-BEETLE, 33
Operations on animals, 189
Opossum, 181
Orang, 7, 38, 194, 201, 208, 241, 253
Organs, larval, 224
Oribi, 89
Orioles, 111
Oryx antelope, 89
Osprey, 105
Ostrich, coloration of chick, 104
duration of youth, 49
eggs of, 101
food of young, 161
longevity of, 49
presence of quills, 97
sexual coloration 69
South American, 105
Otoliths of fish, 52
Otter, 42, 87
Ovary of fishes, 138
Oven-birds, 148, 151
Ovipositor, 124, 127, 138
Owls, 49, 102, 105, III, 149, 153
Oxygen, 234
Oyster, 63, 129
Oyster-catcher, 79

Paints, scaling, 82
Paludina, 130

Pampas deer, 92

Panda, 87

Pangolin, 179

Parasites, 58, 82, 192
Parasitism, 149

Parental care, 118, 161, 262
Parr, 52

INDEX 265

Parrots, 49, 64, 100, 102, III, 149, 153s
161
Partridges, 106, 108
Pattern, in animals, 62
in birds, 112
conspicuous, 75
growth, 81
of mammals, 81, 96
origin of, 113
primitive, 113
as repetition of parts, 64
rupture, 78, 96
secant, 78
spotted, 81
striped, 81
of young animals, 224
Peacock, “eyes” in tails, 76
pheasant, 71
sexual coloration, 69
Peat-moss, 193
Peccaries, 45, 171, 184, 218
Peckham, Mr. and Mrs., 235
Peewit, 99
Pelage, 87, 96
Pelicans, 49, 104, 110, 153, 162)
Penguins, 63, 97, 102, 104, 107, 110, 149,
153, 157
Perennibranchs, 60
Performing animals, 212
Pets, 213, 216
Petrels, 102, 149, 154, 162
Phalarope, 70, 109
Pheasants, 69, 71, 106, 108, 24r
Pholis, 135
Phototaxis, 232
Phototropism, 232
Phyllomedusa, 14
Pigeons, 49, 101-103, III, 150, 153, 162
Pigments, 66, 154
Pigs, 46, 93, 164, 171, 175
Pike, 233
Pipe-fish, 137
Placenta, 138, 139
Plant-lice, 54
Plants, reaction to light, 232
Platypus, 2
Plovers, 102
Plumage, breeding, 99, 112
coloration of, 104
266

Plumage, “ eclipse,” 110, 112
of nestlings, 78, 102, 107
sexual, 69, 110
successive, 99, 108

Pocock, R. I., 198

Pointer, 42

Poisonous plants, 244

Polar bears, 42, 77, 86, 168, 169

Polecat, 42, 87, 169

Polygordius, 24, 25

Polyps, 117, 233

Pompilide, 128

Pond-snail, 130

Pond-tortoise, 143

Porcupine, 176

Porphyrio, 241

Porpoise, 75, 240

Poulton, Professor E. B., 76

Pout, 136

Prairie-dogs, 178

Prawns, 29, 121

Preen-gland, 184

Prolegs, 32

Prongbuck, 91

Protection, coloration, 74, 155
of larva, 224
by spots and stripes, 96
of young, 225

Protein, 185

Protococci, 117

Protopterus, 135

Protozoa, 6

Puffin, 149, 153

Puma, 85, 167

Puppies, 10, 87

Pycraft, W. P., 102

Pythons, 146, 196, 197

QUADRUPEDS, 240, 241
Quail, 106
Quills, 97, 98

RaBBITS, 3, 46, 72, 75, 77) 1495
Raccoons, 10, 87, 169, 176
Rails, ror, 102, 104

Rainbow, 112

Rana, 140

Ratel, 79, 87, 147

Rats, 46, 176, 178, 231

INDEX

Rays, 139
Reactions of living matter, 236
Recognition, 71, 131, 145
Red deer, 92
Reed-buck, 89
Reindeer, 92
Regent’s Park, squirrels in, 147
Reptiles, ancestors of birds, 159
mammals, 163
breeding, 51
feeding, 196
incubation, 163
longevity, 50
reduction of family, 142
sexual coloration, 70
size, 48, 50
skin glands, 184
scales, 81
young, 15, 51, 176, 195
Respiration, 113
Rhacophorus, 142
Rhea, 101, 107, 154, 161
Rhinoceros, 45, 93, 94, 172, 190
Rhinoderma, 141
Rhubarb, 194
River-hog, 93, 218
Roan antelope, 89
Rock-hopper, 104
rabbit, 44, 173
Rodents, 46, 77, 95, 147, 164, 175 177,
178, 204, 219, 234
Roe of herring, 222
Roe-deer, 92
Rollers, 153
Romanes, Professor J. G., 201
Rookeries of penguins, 104, 152
Rose, W., 56
Ruby-flies, 127
Ruminants, 46, 87, 93, 170, 184

SaBLeE antelope, 89
Salamander, 2, 17, 40

Saliva, nests of, 152

“ Sally,” the chimpanzee, 209
Salmon, 52, 135

Sambur, 92

Samlets, 52

Sand-goby, 135

Sand-grouse, 101
INDEX 267

Sand-martin, 149

Sardine, 117

Sargasso Sea, 137

Sunflies, 126

Scarabeus, 128

Schizopod, 29

Scorpion, 121

Screamer, 102, 104, 153, 157

Sea, carnivorous population of, 116
food supply of, 117

Sea-anemone, 118, 236

Sea-bear, 87

Sea-birds, 110, 152

Sea-cucumber, 119

Sea-gulls, 62

Sea-horse, 137

Sea-lions, 10, 87, 214

Sea-squirts, 118

Sea-urchin, 119

Seal, elephant, 194, 214

Seals, 10, 42, 87, 214

Sebaceous glands, 185

Secretary bird, colour of eggs, 154

Secretion of milk, 188

Seedlings, food of, 183

Selection, 58, 66, 70, 75, 113

Selenka, E., on embryology, 9

Selous’ antelope, coloration figured, go

Senses of vertebrates, 54

Serpents, 15, 83, 184

Serval, 85

Setter, 42

Sex, battle of, 207
determination of, 202

Sexes, coloration of, 69

Sexton-beetles, 129

Sharks, eggs of, 139

Sheep, 75, 88, 219

Sheldrake, 107

Shells of eggs, 152

Shore-birds, 79, 101

Shrew, 49,175

Silkworms, 205

Silurus, 137

Silver-fish, 33

Singing birds, 101, 108

Sitatunga antelope, 90

Size and duration of youth, 4o, 47, 48
and food, 48

Size and temperature, 48
Skin, 83, 105
glands, 184.
Skink, 145
Skunk, 72, 79, 87
Sloths, 178, 220
Sloughing by snakes, 83
Slow-worm, 145
Smell, sense of, 243
Smooth-hound, 139
Snails, 130
Snakes, 75
breeding, 146
coloration, 72
€8ss, 145
fascination, 57, 202
fear of, 199
feeding of, 196, 197
viviparous, 146
Snipe, 70, 78, 109
Sole, 22, 63
Solenostomus, 137
Somnambulism, 229
Song of birds, 252
Sound, reaction to, 250
Sparrow, 98, 115, 116
Speke’s antelope, go
Spiders, 15, 70, 71, 121, 123, 128, 205,
230, 235
Spirits of youth, 244, 245
Spoonbills, 154
Spoon-feeding, 189
Spots of animals, 78, 81-85, 89, 92, 96,
113
Squirrels, 147, 176, 177
Stampedes 252
Starfish, 23, 119
Starling, 103, 148
Stick-insects, 124
Stickleback, 129, 130, 136
Stimulation, 232, 235, 236
Stock-breeders, 58
Stomach, 187
Stone-curlew, 149
Stone-flies, 125
Storks, 49, 110, 153, 161, 242
Stripes of animals, 78, 81, 82, 84, 89, 93
95, 96
Structure and colour, 113
268

Struggle for existence, 36
Struthidea, 151

Suckers, 135

Suckling, 235, 243
Sugar, 186
Summer-duck, 107
Sunlight on skin, 76
Swallows, 151, 152, 241
Swamp-deer, 92

Swans, 102, 104, 153, 161
Swarm-spores, 232
Sweat-glands, 185
Swifts, 102, 103, 152
Swimming, 240

Swine, 45, 171, 216

Tasoo, 132
Tadpoles, 18, 20, 51, 59, 200
Tail, 17, 97
Tailor-bird, 150
Takin, 13
Talking birds, 253
Taming and tameness, 204, 205, 207, 221
Tanager, 100, 112
Tapirs, 45, 62, 67, 93, 172, 190, 218
Tasmanian devil, 180

wolf, 96
Tasting, experimental, 73
Temperature, 48, 50, 54, 156, 162, 185
Termites, 125, 132
Terns, 107
Thayer, Abbott, 75, 76, 77
Thomson, Sir Wyville, 119
Thrushes, 103, 111, 150
Thylacine, 96, 180, 220
Ticks, 82
Tigers, 10, 41, 75, 78, 84, 85, 214, 249
Timber-wolf, 10
Tinamou, roi, 107, 154
Titmouse, 103
Toads, 15, 51, 59, 76, 141, 140, 184
Todies, 153
Tortoises, 15, 143, 195, 196
Toucans, 66, 153
Tow-net, 117
“Towns” of beavers, 177
Tree-bear, 180
Tree-frogs, 17, 59, 140
Tree-hyrax, 44, 174, 194

INDEX

Tree kangaroo, 179
Trochophore larva, 25, 26
Trogons, 153

Tropisms, 232-234; 236
Trumpeter, 153

Turaco, 154, 159

Turbot, 21, 115, 134
Turkey-vulture, 50
Turtles, 143, 144

UMBRE, 150

Ungulates, 45, 46, 87, 93) 171, 172, 174»
204, 215

Unpalatability, 72

Urodeles, 59

Utility, 63, 74

VARIABILITY, 58
Vegetation, 116, 243
Veliger, 26

Vermin, parasitic, 82
Vertebrates, 53, 54, 134, 237
Vicugna, 93, 218

Vitality of youth, 224, 245
Voice, 168

Vorticella, 236

Vultures, 49, 103, 105

WADERS, 107
Walk, learning to, 241
Wallaby, 179
Wallace, A. R., 72
Walrus, 214, 243
Warrens, 176
Wart-hog, 93, 218
Wasps, 73, 127, 128, 132
Water-beetle, 129

chevrotain, 93

deer, 92

fleas, 120

fowl, 98

hen, 104

spider, 122
Weaning, 169, 191
Weasels, 10, 42, 87, 169
Weaver-birds, 110, 112
Webs, spiders’, 122, 230
Weismann, A., 57
Whales, 75, 240
Whelk, 130
White ants, 125
Whitebait, 137
Wings, 97, 108, 240
Wolf, 86, 96, 184, 220
Wolf-fish, 135

spiders, 123
Woodcock, 78, 160
Woodpeckers, 102, 149, 153, 161
Wood-pigeons, 207
Worms, 118, 120, 192, 233
Wren, 49

York, 163
Youth, definition, 1, 3

duration, 37, 40, 475 54s 55s 225
games, 246

INDEX 269

Youth, growth of brain, 229
instinct in, 238, 243
mind of, 254
purpose of, 222
spirits of, 245
summary of, 254

Yung, E., 203

ZEBRAS, 45, 759 95, 115, 172; 217

Zebra-duiker, 89

Zoéa, 29

Zoological Gardens, London, 38, 41, 51,
86, 124, 147, 150, 158, 165, 166,
168, 194, 201, 208, 212, 214, 218,
247