Hutchinson’s
Nature
Library
THE COURTSHIP OF ANIMALS
[Illustration: Plate 1.
LOVE-MAKING.
Frontispiece.]
The
Courtship of Animals
BY
W. P. PYCRAFT
OF THE
ZOOLOGICAL DEPARTMENT OF THE BRITISH MUSEUM: FELLOW OF THE ZOOLOGICAL
SOCIETY OF LONDON; ASSOCIATE OF THE LINNEAN SOCIETY: MEMBER OF THE
ROYAL ANTHROPOLOGICAL INSTITUTE; MEMBER OF THE BRITISH ORNITHOLOGISTS’
UNION; HON. MEMBER OF THE AMERICAN ORNITHOLOGISTS’ UNION; ETC., ETC.
Author of “A History of Birds,” “The Natural History Museum,” “Pads,
Paws and Claws,” “The Infancy of Animals,” etc., etc., etc.
_With 40 Plates on art paper Containing over 80 Illustrations_
_THIRD EDITION_
LONDON
HUTCHINSON & CO.
PATERNOSTER ROW
I DEDICATE THIS VOLUME
TO
H. ELIOT HOWARD
WHOSE OBSERVATIONS OF THE COURTSHIP OF BIRDS RECORDED IN HIS “HISTORY
OF THE BRITISH WARBLERS” CONSTITUTE A BEACON FOR ALL ENGAGED IN THE
STUDY OF ANIMAL BEHAVIOUR
PREFACE
That “one touch of Nature which makes the whole World kin” is surely
nowhere more obvious than in the “Courtship” of Animals. For the
“Beasts that Perish,” no less than Man himself, are stirred by the
same emotions; the Fever of Love runs as high in them as in ourselves;
and its modes of expression are not so different, though they may
superficially appear to be so. The nature of these differences and
their interpretation, it is the purpose of this book to set forth.
Charles Darwin laid the foundation for the study of this phase of
Animal behaviour in his masterly work on the “Descent of Man,” a work
which has been much criticized and much misunderstood since Carlyle’s
crude abuse of it as the “Gospel of Dirt.” Darwin was the first to show
us that the fierce battles, and strange antics, which characterize so
many of the “Lower Orders of Creation” under the exaltation of the
Sexual emotions are manifestations fraught with tremendous consequences
to the race.
The facts which he brought to light, and the discussions to which
they have given rise, have, however, unfortunately been too commonly
regarded as merely interesting to those who have a liking for Natural
History.
This is a most unfortunate mistake. For such facts have a vitally
important bearing on the very problems of social well-being which now
loom so largely among us. “Reform” is in the air. Its protagonists
are busy amongst us with schemes for our regeneration, among which
“Sex-problems” are made to occupy a very conspicuous place. But no
good can come of their cogitations so long as they fail to realize the
springs of behaviour in this regard. The facts herein set down will, it
is hoped, help much towards this end.
My labours in the preparation of these pages have been materially
lightened by the help and counsel of many friends. To them I desire now
to record my very grateful thanks. More especially am I indebted to my
friends Mr. H. Eliot Howard, Professor Lloyd Morgan and Mr. John Cooke.
I must also thank those who have contributed towards the illustrations
which enliven these pages. The delightful Frontispiece, and many of the
plates scattered through this work, I owe to the generosity of Messrs.
Rowland Ward, Limited. The excellent rendering of the Birds of Paradise
adapted in part from the work of Mr. G. E. Lodge and the late J. G.
Keulemans, and partly drawn from specimens in the British Museum, is
the work of Mr. Roland Green. The very difficult, and less fascinating,
technical figures I owe to the skill of Mr. Philip Whelpley. The
wonderful photographs illustrating the “Display” of the Sun-bittern and
the Kagu were taken by my friend Mr. D. Seth-Smith.
Finally I have to thank Mr. Roger Ingpen for the immense amount of
trouble which he has taken in seeing these pages through the press.
W. P. Pycraft.
October, 1913.
CONTENTS
CHAPTER
INTRODUCTION
The nature of Life and its power of reproduction—The
stuff of which Life is made—The Emotions—The simplest
living things—Where is neither Birth nor Death yet the
Population increases—The First Marriage—The beginning
of sex—The two dominating instincts—The conditions
of survival—The Oyster’s narrow world—“Fiddling
work”—Amorousness—The superior Male—Where Death
begins—“Germ-plasm” and what it means—Sex and “Secondary
sexual Characters”—Some theories—“Hormones” what are
they? 1
CHAPTER II
“MANKIND IN THE MAKING”
The use of the term “Courtship”—Primitive Man and
the Foundations of Society—“Amorousness” as a motive
force—Polygamy—Our half human ancestors—Standards of
Beauty—Disquieting signs 21
CHAPTER III
MAN’S COUSINS THE APES
The Man-like Apes and their mode of Life—Their
“Courtships”—Musical Chimpanzees—How the Orang-utan
improves his voice—His likeness to Caliban—The truculent
visage of the Gorilla—“Ornament” in the lower Apes—The
Concerts of the Howler Monkeys 40
CHAPTER IV
AT DAGGERS DRAWN
The Birth of Weapons—All Flesh is Grass—Utility and
Ornament—The Fever of Love—The “Challenge” of the
Deer—What it means-More about “Hormones”—“Hummel”
Stags—The Age of Deer—The “Courtship” of the Moose—Types
of Antlers—Antlered Females—Fighting Topi—The Lance
of the Oryx in the Lion’s Flanks—Happiness and
Hartebeestes—Odoriferous Suitors—The Bloody Sweat
of the Hippopotamus—The Elephant in Love—Concerning
Tusks—Polygamy 49
CHAPTER V
THE LION AND HIS KIN
A Surprising Relationship—The Lion’s Mane—The
Sabre-toothed Tiger—Some Theories about Origins—Sea-lions
in Love—Some Strange Ornaments—Whales and Weapons 77
CHAPTER VI
COURTSHIP AMONG BIRDS
Generalities—Darwin v. Wallace—The Peacock in his
Pride—The “Display” of the Peacock Pheasant—The
Splendour of the Argus Pheasant and the Marvel of
its Eyes—The Frill of the Amherst Pheasant—Birds of
Paradise in the Toils of Love—Inflated Suitors-Ruffs
and Reeves—Fearsome Weapons and their Uses—Birds which
dance-Musical Birds—The Bird’s Voice-box—The “Lek” of
the Capercaillie—Instruments of Percussion—The Curious
Performance of the Woodpecker 92
CHAPTER VII
THE SEXUAL SELECTION THEORY AS APPLIED TO BIRDS
Where the Rôle of the Sexes is reversed—Polygamy and how
it is brought about—Coloration and Courtship—Instinctive
Actions—The Importance of Landed Possessions—The Meaning
of “Display”—The Springs of “Behaviour”—A New Light
on the Wild-duck—The “Display” of the Great-crested
Grebe—Some Neglected Factors 134
CHAPTER VIII
SOME “COLD-BLOODED” LOVERS
The Courtship of the Crocodile—Amorous Lizards—Horned
Chameleons—A Flagellating Terrapin—The Frog that would
a-wooing go—Some Musical Frogs—Some marvellous instincts
in Newts 161
CHAPTER IX
LOVE-MAKING AMONG THE FISHES
Germinal variations—Fishes and Mate-hunting—Some
Remarkable Sexual Differences displayed by the Teeth
of “Rays”—The Double-eyed Fish—The Coloration of the
Dragonet—Some Curious Facts about Salmon—The Strange Use
of the Kidney in the Stickle-back—The Stickle-back and
Parental Duties—Siamese Fighting-fish 175
CHAPTER X
SOME OF THE “LOWER ORDERS”
Butterflies and Moths, and the Coloration of their
Wings—Female Choice and “Fine Feathers”—When Male
Butterflies are Dominant—Sexual Selection among
Butterflies—Abortive Experiments—Wallace and the Sexual
Selection Theory—The Sense of Smell in Butterflies and
Moths—Fragrant Butterflies—Wingless Moths and their
Lures to Lovers—Methods of Pairing among Butterflies and
Moths—More Experiments 185
CHAPTER XI
BEETLES THAT “BLUFF”
The Coloration, and other Forms of Ornament in Beetles,
and the Significance thereof in regard to the Sexual
Selection Theory—The Courtship of Grasshoppers and their
Kin—The Remarkable Ears of Locusts and Grasshoppers—The
Field-cricket and the Katydid as Troubadours—The
Wonderful Performances of the Cicadas—The Duels of
Long-horned Locusts—Dragon flies—The May-flies’ “Dance of
Death”—The Jaws of the Giant Alder-fly and their Strange
Use—Some Curious Facts about Stone-flies 208
CHAPTER XII
SCORPIONS, SPIDERS AND CRABS
Musical Lovers among Spiders and Scorpions—Colour
among Spiders, and its uses—The Spiders’ Dance of
Death—Spiders and Conjugal Bliss—How Pairing is
accomplished—Scorpions in Love—Musical Crabs—Quarrelsome
Fiddler-crabs—Crabs and Courtship in the Deep Sea-Amazons
among Prawns—Brine-shrimps and Water-fleas—“Natural” v.
“Sexual” Selection 236
CHAPTER XIII
SOME STRANGE MARRIAGE-CUSTOMS: AND VIRGIN BIRTHS
The Courtship of the Cuttle-fish—The Sumptuous Cradle of
the Argonaut—The Love-darts of the Snail—Hermaphrodites
and the Dangers of Self-fertilization—Oysters and
Beauty—Sex reduced to its Lowest Terms—Parthenogenesis
and Virgin Birth—The Story of the Hive-Bee—The Departure
of the Queen—The New Queen and her Marriage-flight—The
Celebration of the Nuptials and its Surprising Sequel—The
Widowed Queen turns Executioner—The Queen as Mother—The
Queen’s Daughters—Nursemaids’ Duties—Change of Work—The
Drones and their Career—Food and Sex—The Bumble-bee and
its Life-story 265
CHAPTER XIV
PARTHENOGENESIS AND ITS SEQUEL
Courtship among the Ants—The Great Renunciation—Maternity
carried to Extremes—Where Males are
Superfluous—Degenerate Males—Keeping Death at Bay—Where
Females are Unknown 296
LIST OF ILLUSTRATIONS
Love-making Frontispiece
Facing page
The Gorilla preparing for hostilities 42
The barometer of maleness—among the Apes 44
Weapons of offence 52
Manchurian Wapiti “calling” 54
Group of Beisa Oryx 60
Eland Cows 64
American Bison 64
Elephants 70
Head of male Wart-hog 72
Male and female Babirusa 72
Somali Zebras 72
Giraffe 72
Californian Sea-lions, or Eared Seals 82
Elephant Seal 88
Northern Elephant Seal 88
“The Peacock in his pride” 96
Peacock Pheasant 96
Patterns which puzzled Darwin 98
The “Strutting Turkey” 100
The display of the Great Bustard 100
Some of Fortune’s favourites 104
The love-making of the Prairie Hen 110
Grades of evolution in the syrinx or organ of voice in
the males of Surface-feeding and Diving-ducks 126
Fighting for territory 140
The display of the Grasshopper Warbler 142
The display of the Sun-bittern 142
The Kagu in display 142
A male-Savi’s Warbler 152
Another aspect of the Kagu’s “display” 154
Some strange accompaniments of courtship:
The White-headed Bell-bird 156
The Umbrella-bird 156
Skull of the American white-beaked Pelican 156
Head of a Puffin, showing the moulting of the beak
sheath 156
The Satin Bower-bird and its bower 158
The “bower” of the Bower-bird 158
The Bearded Lizard 166
Bright colours which cannot be attributed to “sexual
selection” 200
Stridulating organs, etc. 218
Crickets and May-flies 220
Male Astia displaying before the less brilliant female 242
Male Icius displaying 242
Scorpions 252
Death of the male Scorpion 254
The female Mantis devouring her mate 254
The “Fiddler-crab” among mangrove roots 258
The “Fiddler-crab” 258
Some remarkable devices 262
Some remarkable methods of “courtship” 268
THE COURTSHIP OF ANIMALS
CHAPTER I
INTRODUCTION
The nature of Life and its power of reproduction—The stuff of which
Life is made—The Emotions—The simplest living things—Where is neither
Birth nor Death yet the Population increases—The First Marriage—The
beginning of sex—The two dominating instincts—The conditions of
survival—The Oyster’s narrow world—“Fiddling work”—Amorousness—The
superior Male—Where Death begins—“Germ-plasm” and what it means—Sex and
“Secondary sexual Characters”—Some theories—“Hormones” what are they?
The nature of life is generally regarded as affording a theme which
possesses no more than an academic interest: but there is one aspect
of this great subject which must attract us all, and that is its power
of reproducing itself. Life begets Life, as Love is said to beget
Love. The nature of this mysterious power we can only dimly realize,
and the forces which underlie its manifestations few even suspect,
save perhaps in a vague way. Yet the tree of Knowledge bears no fruit
more vitally important to our well-being, than that which will make us
“as Gods, knowing good and evil” in all that concerns the processes
of reproduction. But curiously enough, this is a forbidden fruit, and
those who eat thereof are expected to maintain a discreet silence on
the subject. These enlightened ones, however, cannot remain altogether
dumb. But they speak, in the veiled language, of Art and Poetry,
Literature and the Drama. They talk round the subject rather than of
it. Love, Hate, Jealousy, and Envy, are but attributes thereof. We
profess to believe that “Knowledge is Power” and to desire to increase
its force among us by raising the standard of our system of education.
But education which does not, of set purpose, reveal the sources of our
being and of our emotions, good and evil, is no more than a travesty
of education; and they who seek to foist upon the community Knowledge
thus emasculated, are unworthy to wield the power which has been placed
in their hands. If social well-being be the aim of the high-priests
of Education, then something more than copybook maxims like “Be good
and you will be happy” must henceforth be preached. Of what avail is
it to exalt the name of Knowledge, while the straightest road thereto
is barred across and marked “No thoroughfare!” These blind leaders of
the blind seem to imagine that the social well-being they profess to
desire can only be attained by side roads, leading anywhere, save in
the direction of this Pool of Siloam.
The stuff of which living things are made is called “Protoplasm.”
Text-books of Physiology give its chemical constituents with fearsome
accuracy, and each of these constituents can be isolated in the
laboratory, but “all the king’s horses and all the king’s men” cannot
build these up again into living matter. Its consistent inconsistency
defies us; every statement we make of it has to be qualified by
reservations and saving clauses. Its permanency is attested by the
fact that it has endured through millions of years, yet we are daily
reminded of its evanescent nature. Its power of reproducing itself
according to type, none can doubt, yet no two individuals are exactly
alike.
The purely physical phenomena of life, to be rightly appreciated, must
always be considered in relation to the psychical phenomena which
are the soul of life. These subtle and intangible forces cannot be
experimented with in the laboratory, or expressed in formulæ; we
cannot denote their strength in horse-power. Just as the physical
manifestations of life begin with lowly types, so the psychical begin,
and they gather strength and complexity with the bodies they pervade.
These manifestations we call behaviour, and in their more intense
developments, “emotions.”
These emotions present an infinite range of variety in the higher
animals, and they attain their maximum of intensity wherever the
reproductive activities are concerned. The part which these activities
play in controlling behaviour is by no means always apparent, and
is commonly not even suspected. Even man himself is subject to this
control. And it is this fact which lifts the “Courtship” of the lower
animals out of the category of merely curious phenomena. For the
springs of his conduct, his behaviour and “emotions” under varying
circumstances, can only be understood, and even then but imperfectly,
by comparison with other creatures lower in the scale, so far, of
course, as comparison is possible.
This line of inquiry, then, takes one back to the simplest living
things, among which there is neither marrying nor giving in marriage,
neither birth nor death. Life is reduced to its simplest terms—a speck
of animated jelly is all that confronts one, and this is only to be
seen under a high power of the microscope. It has neither mouth nor
organs of digestion, no visible means of locomotion are traceable,
and the special senses of sight and hearing are wanting; but taste
and smell, of a nebulous kind, are there. Shape it cannot be said to
have, for its bodily outline is constantly changing, thereby it moves.
A long tongue of its jelly-like substance, or “protoplasm” as it is
called, is thrust forwards, and the rest of the body is, as it were,
dragged after it. Whatever animal, or vegetable, matter it passes
over, in the course of its wanderings, is drawn up into the semi-fluid
substance of this diaphanous body, and its juices extracted, the
undigestible residue is left behind in the course of the morning’s
walk! In due time it becomes adult; further growth is impossible. When
this stage is attained a strange thing happens. A certain minute, more
solid portion of this body, which lies in the very centre of the mass
and is known as the “nucleus,” begins to assume an hour-glass shape.
Speedily the constriction becomes apparent across the whole body and
rapidly increasing, cuts it in two, as if by the tightening of some
invisible thread. Here Death is cheated, and records of births are
unknown! And just as there are no parents so there are no children.
But a foreshadowing of what is to be occurs even here. For every now
and then two individuals, to all appearances identical, meet and
promptly begin to merge the one into the other till they twain become
one flesh in very truth. Here is the most primitive form of marriage
in Nature. And here, in this union, or fusion, of separate entities of
Germ-plasm, we have the beginning of sex. Such unions are common among
these primeval forms of life. In many cases this “marriage” takes place
between two particles of Protoplasm of which one is rather larger than
the other. In such case the smaller is regarded as male, the larger as
female. Here we have the first sign of “sexual differentiation” or the
evolution of “male” and “female” individuals.
Some such union, some such process of “rejuvenation” by the importation
of “fresh blood” seems to be imperative for the continuance of
existence throughout the whole animal world, even though it may take
place at rare intervals of time. Why should this be? Is this strange
meeting and commingling a matter of chance, or is the one seeking the
other possessed by a ravenous mate-hunger?
As we ascend higher in the scale it becomes apparent that life has
gathered force. That primitive speck of jelly, the Amœba, with which
we started, gave but two signs of animation—the power of movement,
and hunger. Whether these responses to internal stimuli can be called
instinctive is open to argument. But there can be no question about
the instinctive nature of the behaviour of these higher animals.
After the instinct to feed the two most powerful are the desire for
self-preservation—the avoidance of danger—and the desire to mate. These
two are the dominating instincts throughout the rest of the animal
world, not even excepting man himself.
The tremendous power of “mate-hunger” has been overlooked by a strange
confusion between cause and effect. Almost universally its sequel, the
production of offspring, has been regarded as the dominant instinct in
the higher animals. This view has no foundation in fact. “Desire” for
the sake of the pleasure it affords, and not its consequences, is the
only hold on life which any race possesses. And this is true both in
the case of man himself and of the beasts that perish. Wherever this
instinct becomes weak, or defective, extinction speedily and inevitably
follows. This “Amorousness” is the motive power of “Courtship” wherever
it is met with; manifesting itself in the eccentric, and often
grotesque posturings, or in the loud and often musical cries which
constitute the study of courtship. Intensity of desire is indispensable
to survival.
Only the lowly and sedentary types, of which the Oyster may be taken
as an example, lack this fire; and here because it is unnecessary. For
the reproductive germs of this animal are discharged into the water,
to take their chance of attaining their object. They are liberated
unconsciously, discharged like the undigested residue of the food,
without effort, and without cognizance of the act. This must be so,
for the Oyster merely lives—vegetates. Sightless, and without power
of movement, after its larval wanderings are over, it lives merely
to eat. And even in this, choice is denied it. The currents of water
mechanically brought to afford the necessary oxygen for the maintenance
of life, bring with them the food which is to restore the slowly
wasting tissues. To such a creature there can be no “outer-world,” no
consciousness of the existence of individuality other than its own.
The desire for sexual intercourse is met with only where the
co-operation of two individuals is necessary to ensure the production
of offspring. Such individuals being free to roam, must have some
incentive to seek one another at the time when their germ-cells have
attained maturity. And this incentive is furnished by the glands in
which these elements are produced: supplemented by the secretions
of certain ancillary glands. These stimulating juices, known as the
“Hormones,” will be presently described.
But if we owe our existence to the gratification of what may be called
our lower instincts, it is no less certain that all that is best in us
we owe to our offspring. We meet with the beginnings of altruism, which
the begetting of offspring entails, far down in the animal kingdom, and
it attains to its full perfection in the human race. Here only, in its
best and truest sense, Love begins: though affection may be found, and
in a high degree, in many of the lower animals.
Living things are as clay in the hands of the potter. But it is as if
they made themselves, for the designer and the guiding hand are alike
invisible. No vessel is exactly like its neighbour, either in the
quality of its substance or in the details of its construction. And
this because the clay of which it is made possesses that mysterious
property we call life. A property which endows each new feature as
it appears, with an individuality of its own, whose survival, or
suppression, depends entirely on its relationship to surrounding parts;
on its harmony with its environment, in short. Colour, size, shape,
temperament, behaviour, may each be regarded as so many entities
depending for survival on whether or not they can exist in harmony with
their environment—the several parts which make up what we call the
individual.
In like manner the individual—the complex bundle of parts and
qualities—must attain, and maintain, a certain harmony with its
environment—the outer world. The process of change, both in quality
and quantity, which is for ever going on among the several parts of
every separate individual, brings about the elimination of unfavourable
variations; and “selects” those which vary in the right direction:
that is to say, which serve to maintain a place in the sun for the
individual in which these momentous changes are going on. But it is not
enough that the individual should be in “working order”; it must be in
harmony with all the conditions on which existence depends. And the
standard of this harmony is set by that very exacting arbiter of life
and death, “Natural Selection.” It is not enough that the instincts
in regard to this or that habit should be keen, or that this or that
particular organ of the body should be efficient—a certain minimum,
all-round, standard of efficiency is demanded, or elimination follows.
It is through this instability of “temperament,” this tendency to vary
in infinite directions, that the balance between the individual and
the environment is maintained. Evolution follows the line of least
resistance.
The little boy who remarked that it must be “fiddling work, making
flies,” was more sage than he knew. The complex web of factors which
even a fly represents are beyond the grasp of human understanding. But
it is clear that the reproductive instincts, and the emotions they
beget, have played, and play, a tremendous part in the evolution of the
higher animals.
Those whose business it is, for one reason or another, to study
these emotions know well that “mate-hunger” may be as ravenous as
food-hunger, and that, exceptions apart, it is immensely more insistent
in the males than in the females. But for this, reproduction in many
species could not take place: for the sexes often live far apart, and
mates are only to be won after desperate conflict with powerful rivals
no less inflamed. Thus it is idle to speak of an equality between the
sexes in this matter, in regard to the human race. Dogmatism, and the
frequent repetition of pretty platitudes, will not alter what Nature
has ordained. The failure to realize this is painfully obvious in
the utterances of many who speak in the name of the newly-founded
“Eugenics” society, which seeks the means to ensure the well-being
of the race by the spread of a more intimate knowledge of this
all-important subject. The existence of what Mr. Heape has recently
called a “sex-antagonism” is beyond dispute, for the instincts of the
male and female are fundamentally different. The male is dominated
by the desire to gratify the sexual appetite; in the female this is
counteracted by the stimulation of other instincts concerned with the
cares of offspring.
Amorousness, then, is the dominant feature of the males among all
animals: and this sex presents yet another characteristic which is to
be borne in mind. In all that concerns the evolution of ornamental
characters the male leads. In him we can trace the trend which
evolution is taking; the female and young afford us the measure of the
advance along the new line which has been taken. Why this should be is
inexplicable. But sooner or later the females assume, or will assume,
all the features originally possessed by their lords; and finally the
young also follow suit. That is to say, the females and young tend to
retain the ancestral characters. In the course of time the ability to
develop new features by the male loses its impetus, and not till then,
apparently, do the females, and still later, the young, begin to share
his glory. These remarkable features are strikingly illustrated among
the birds, as these pages will show.
Nature is nothing, if not perverse. And hence it happens that there
are many exceptions to every rule which one formulates. Among the
birds, for example, there are species wherein the rule that the female
follows her mate in the acquisition of new characters is, so to
speak, set aside. She follows a line of her own. This is true, at any
rate, of superficial characters, such as coloration. By some curious
change in her “metabolism,” as the conversion into living tissue of
the substances taken as food is called, this coloration may attain
a brilliance in no way inferior to that of the male, but strikingly
different. The beautiful Orange Fruit-pigeon (_Chrysoenas victor_)
furnishes a case in point, the male being of a gorgeous orange-yellow,
the female of a no less vivid green. But the differences are not so
great as they appear at first sight. For the male was originally green,
and the female has thus but intensified the ancestral livery. Green,
it should be remarked, of a more or less olive shade, always precedes
yellow in development; and yellow may yield to red, but this order is
never reversed. A no less striking case is that of the Upland Goose
(_Cloephaga magellanica_), the male of which is pure white, while the
female wears a livery of chestnut and brown. But so sharply are the
colours defined that it would be difficult to say that one was of a
higher order of coloration than the other. To what causes or factors
are these departures due?
Reproduction in the simplest living things takes place by a simple
division of the body into two as soon as its maximum size or adult
condition has been attained. In such simple types the body consists
only of a single “blob,” or particle, of jelly. But a new era began
when large numbers of such particles, or “cells,” began to form
coherent masses, different parts of the mass performing different work
for the mutual benefit of the community. Some have come to form what
we call the body, which is born, and in due course dies. Others are
alone concerned with the task of reproduction. They are nourished by
the body, and on attaining maturity, give rise to new bodies. These
reproductive cells are excessively small. The male, or “sperm” cell,
can only be distinguished under the highest powers of the microscope.
The female cell, or “Ovum,” is always larger than the male, because, in
addition to the germinal matter which it contains, it is furnished with
a store of food in the shape of yolk. This accounts for the relatively
enormous size of the egg of the hen. Within the hardened shell the
germ develops into the chick, deriving food for its growth from this
generous store. Where this yolk is limited in quantity the growing
body is hastily fashioned, and launched forth into the world in the
form of a “larva,” when it must forage for itself till it has attained
its adult form. Or it is retained within the body of the mother until
development is complete.
The reproductive cells are the bearers of the Germ-plasm, the stuff
of which man and the beasts of the field alike are fashioned. Only a
portion of this germ-plasm gives rise to a new body; the rest is, as it
were, held over and stored within the new body to give rise to another
in due course. That which produces the body we call the “Somatoplasm,”
because it is the “plasm” or stuff of which the “Soma,” or body,
is made. As to the nature of this Germ-plasm and its mysterious
properties, a wide divergency of opinion exists among _savants_. But the
views which find most favour to-day are those of the veteran Professor
August Weissmann, as set forth in his work on the “Germ-Plasm, a Theory
of Heredity.”
The excessively minute quantity of this germ-plasm which suffices
to form a new body is incredible. By what miracle of miracles is
the essence of a man distilled? His body arises from the union or
commingling of two particles of living matter so minute as to be
invisible to the naked eye. One of these particles is the “sperm”—cell
furnished by the male parent; the other, the “ovum,” furnished by
the mother. True the ovum may measure as much as the one-hundred and
fiftieth part of an inch, but the bulk of this is yolk-food necessary
to furnish the tender germ with life and energy till it shall have
attached itself to the walls of the womb, whence all its future
nourishment is derived.
By no process of analysis known to us could the germ-plasm of man be
distinguished from that of, say, a jelly-fish; and in the matter of
quantity there is no more difference. Yet, identical to our senses, in
potentiality how amazingly different are these two particles of jelly!
In the lowliest animals, such as jelly-fish, one cannot distinguish
male and female at sight. The appearance of separate male and female
individuals begins somewhat high in the scale marking an epoch in
the history of animal life. For the birth of sex inaugurated not
merely individuals producing distinctive “male” and “female” germs,
but individuals which, by virtue of their sex, developed differences
of behaviour and mentality which were to be followed by tremendous
consequences. Certain aspects of this behaviour are to furnish the
theme of these pages; others, and no less important, those who will may
discover in Professor Arthur Thomson’s “Evolution of Sex.”
We are far, indeed, from being able to explain the attributes of sex.
At most, we can but endeavour to interpret the behaviour associated
therewith. This was the task which Darwin set himself to achieve in
his theory of sexual selection. He was influenced in the train of
thought which he followed up with such brilliant success by what he had
observed in the behaviour of highly-ornamented species, such as the
Peacock and the Birds of Paradise. The strange antics of these birds
when under the influence of sexual excitement persuaded him that they
were at least dimly conscious of their splendour, and of its power
to fascinate. The female, on the other hand, was supposed to be coy,
and to bestow her person on the finest performer. In this way the
dullest birds and the poorest performers were gradually eliminated.
Here, indeed, was sexual selection. The frills thus begotten he called
“Secondary Sexual Characters,” a term which is also used, and was used,
by him, to include any feature whereby the sexes can be distinguished
apart from the character of the genital organs.
Horns, tusks, and spurs are other forms of secondary sexual characters.
And these stand for another form of sexual selection—that of selection
by battle. Herein victory falls to the strongest and most pugnacious
male who, as the spoils of victory, annexes the females which formed
the subject of the duel. This theory, which must be discussed at
greater length in the course of these pages, has had many critics,
and among them men of mark. But whatever modifications may be deemed
necessary, they will be such as are demanded by the results of later
discoveries rather than to the force and subtlety of the arguments of
his opponents.
One of the most formidable of the opponents of the Sexual Selection
theory was Wallace. But his arguments were far from convincing, and
often inconsistent. He attributed the more frequent occurrence in male
animals of brilliant coloration and exaggerations of growth such as
give rise to manes, beards, long plumes, and so on, to a “surplus of
strength, vitality and growth-power which is able to expend itself
in this way without injury,” or, as he sometimes expresses it, to
superabundant vitality. He was evidently striving to find words for
the faith that was in him, and he was nearer the truth than he knew
or than his critics supposed. He was seeking facts which only the
physiologist could furnish. And these made their appearance long years
after with Professor Starling’s discovery of Hormones. We are far from
understanding the origin of these mysterious juices which must be so
frequently alluded to in these pages, but they are evidently intimately
associated with the expenditure of energy. This may sometimes find an
outlet in increased stature, sometimes in pure luxuries of growth. The
force of Wallace’s arguments was crushed out by the weight of detail
they were made to bear.
Mr. J. T. Cunningham a few years ago entered the lists and failed to
achieve his purpose no less completely. His was a theory which assumed
too much. In the first place it was based on the transmissibility of
acquired characters, of the truth of which there is at present no
evidence.
He contends, for example, that the vivid hues of scarlet, blue, yellow
and violet which colour the naked skin of the neck of the cassowaries
and of both sexes, and the curious horny casque which surmounts the
head, are the outcome of the constant laceration of the skin inflicted
by the males during their conflicts for the possession of the females.
He assumes that such conflicts take place, and he assumes that such
“acquired characters” are transmitted. Now, as a matter of fact, these
birds do not fight with their beaks, but with their feet. And to this
end the claw of the inner toe is enlarged to form a great spur. But
there is no evidence that the skin of the neck is ever damaged in such
conflicts as they may engage in. No scars are ever found, at any rate,
to lend support to this theory. The casque, which is similarly supposed
to be a mark of honourable conflict, is an “ornament” of great frailty,
for it is composed of a delicate filigree-work of bone covered with a
thin sheath of horn. In like manner, the long plumes which surmount the
heads of birds like the Peacock, and many Birds of Paradise, and the
wattle which surmounts the beak of the Turkey, are supposed to have
had their origin in similar pugilistic encounters in the past. Mr.
Cunningham is surely pushing the theory of the transmission of acquired
characters a little far. For what has been transmitted in these cases
is not a number of scarred surfaces, but a series of hypertrophied
structures. An amazing array of ornamental characters, symmetrically
disposed, and often vividly coloured, in short, has been produced from
lacerated tissues which in kind and extent can have varied but little.
Evidence has been accumulating during the last few years which would
have rejoiced the heart of Darwin. Had he known that birds of sober
hues “display” with the same animation and with as much elaboration
of posture as the Peacock and the Pheasant, his theory of “Sexual
Selection “would probably have left little for those who came after him
to criticize. Since his time it has been discovered that both permanent
and recurrent secondary sexual characters, such as the antlers of
deer and the temporary nuptial plumage of birds, such as the Ruff for
example, are controlled as to their growth by the stimulating action
of the “secretions or juices formed by certain of the ductless glands
“; that is to say, of glands having no apparent connection with their
surrounding tissues. We owe much of our knowledge of this subject to
Professor Starling, who has called these secretions “Hormones.”
Darwin knew that the essential sexual glands, the testes and the
ovaries, in some mysterious way controlled, in a large degree, the
development of these “hall-marks” of sex, for it was known in his
time that castrated stags failed to produce antlers, and that hen
pheasants, for example, in extreme old age, or when the ovaries were
damaged by disease or injury, at once assumed the plumage of the cock;
but the part played by these ductless glands was quite unsuspected.
They are the Thyroid, and the Thymus glands, which are attached to
the outer walls of the trachea or windpipe. The Pituitary body, which
forms part of the brain, and the Suprarenal bodies, attached to the
kidneys. It would be foreign to the purpose of these pages to enter
into the functions of these glands; suffice it to say, that the juices
formed therein are taken up by the blood, and distributed over the
system. Their action is only very imperfectly understood. We know
that any derangement in their efficiency results in disease, and that
they play a very important part in the reproductive system, as will
become abundantly evident in the course of these pages. Much hitherto
attributed to the action of “Sexual Selection” alone, it is now evident
is largely due to their action.
The all-sufficiency of the “Sexual Selection” theory to account for
the development of armature, such as horns, antlers, and the huge
spine-like outgrowths which form so conspicuous a feature of many
of the extinct Land-dragons, or Dinosaurs, has been by no means
universally accepted. Some authorities like Dr. A. Smith Woodward and
Professor Osborne interpret these after another fashion. They hold
that these are the “expression points” of inherent growth forces, a
process of concentration marking the final stages of evolution prior
to extinction. From which it may be inferred that there is a term to
the life of a species as there is to the life of the individual. In
many cases it is suggested the very exuberance of growth has been the
exterminating factor, as in the case of the huge antlers of the Irish
“elk,” whose enormous weapons hampered his endeavours to escape his
enemies. This is the theory of “Orthogenesis,” or direct development.
According to this, new structures, arising in the germ-plasm as
“variations,” will of their own inherent vitality go on increasing in
each generation unless, and until, checked by “Natural Selection.”
Changes in the character of the “Hormones” might very well bring
about these excesses of growth. It is well known that the exuberance
of growth which produces giants among the human race is due to a
derangement of the secretions or hormones of the pituitary body which
largely control growth.
Another factor of Sexual Selection which is commonly ignored, but which
is of profound importance, is to be found in the part played by the
emotions in regard to sexual relationships; the part which the “mind”
has played, and plays, in the mating of animals, at any rate of the
higher types.
Darwin touched but lightly on this theme. Later writers have almost
entirely ignored it. Almost all that is worth knowing on the subject
we owe to Professor Lloyd Morgan, who was one of the first to take up
this difficult line of investigation, and to Professor Groos. Their
researches have shown that there can be no doubt but that the emotions
have played and are playing an important part in the phenomena we are
striving to analyse. Sexual selection, in short, is concerned not
merely with the evolution of the physical characters of the body, but
also, and no less, with the psychological attributes thereof. Many new
and extremely valuable facts in this regard have been brought to light
by Mr. H. Eliot Howard in the course of his remarkable studies on our
native warblers. Not until the psychology of sex in the lower orders
of creation has been further investigated shall we have a properly
balanced account of the part played by sexual selection in the scheme
of evolution.
By now it will have become apparent that the study of the “Courtship”
of animals is one of alluring interest and full of pitfalls for the
unwary. And this because of the apparent difficulty in drawing any
hard-and-fast line between the part played by “Natural” and the part
played by “Sexual” Selection, at any rate in some cases.
To this aspect of the theme Professor Lloyd Morgan has drawn particular
attention. “It is difficult,” he remarks, to accept the view that
individual choice has played no part where the sexual instincts are
concerned. But supposing that it has played its part ... the effects
will be wrought into the congenital tissue of the race if, and only
if, there are certain individuals which, through failure to elicit the
pairing response, die unmated. Is preferential mating, supposing it to
occur, carried to such a degree that some individuals fail to secure
a mate? That is the question. If so, sexual selection is a factor in
race progress; if not, though it may occur in nature, it is inoperative
as a means of evolutionary development. The whole question, in itself a
difficult one, is further complicated by the fact that the males which
are possessed of the most exuberant vitality, and are therefore by
hypothesis rendered the most acceptable through emotional suggestion,
are likely to compete with other males of less exuberant vitality by
direct combat. Such competition, by which the weakest are excluded from
mating through no choice on the part of the female, falls under the
head of natural selection, and not of sexual selection, if by that term
we understand preferential mating.
“This serves to bring out the difference ... between natural selection
through elimination and conscious selection through choice....
Sexual selection by preferential mating begins by selecting the most
successful in stimulating the pairing instinct.... The process is
determined by conscious choice. It is in and through such choice that
consciousness has been a factor in evolution.”
Herein Lloyd Morgan, like Darwin, recognizes the existence of a
dual machinery in determining survival, where this depends on the
co-operation of two individuals leading separate existences—Natural,
and Sexual, Selection—sometimes the one and sometimes the other
prevailing. In the former, the females are seized by force; in the
latter, won by displays.
But is this really so? In these pages it is contended that a sharp
line must be drawn between all those attributes and characters which
are necessary to achieve individual survival, the survival of the
Ego, and all those which, on the other hand, are necessary to achieve
reproduction and the survival of the race. The former are governed, or
determined, by Natural, the latter by Sexual, Selection.
The sphere of influence of these two factors may be delimited, if
we regard natural selection as the factor accountable only for the
qualities necessary for the survival of the individual—necessary to
ensure success in the struggle for existence. Then it will become
apparent that the qualities and attributes necessary to achieve the
survival of the _race_ are of a different kind, and these are the
factors which are embraced under the term “Sexual Selection.”
It is a mistake to regard animals in relation to the selection theory
as if they were so many tailors’ “mannikins.” Yet a large number of the
critics of the selection theory seem to fall into this error, ignoring
all but the most superficial characters.
The peculiarities of colour, structure and behaviour, that is to say,
the characters and qualities which distinguish the individuals of any
given race, are due to inherent qualities of the germ-plasm. Each of
such qualities, therefore, may be regarded as entities. Selection
determines their survival. Intracellular selection is the first sieve
through which they have to pass, natural and sexual selection are
others, as circumstances may determine.
As a rule the sex of an individual is attested by more or less
conspicuous external features. These are known as the “Secondary Sexual
Characters.” But no hard-and-fast line can be established for these,
at any rate, so far as colour and ornament are concerned, for such, as
will become apparent in the course of these pages, tend to appear first
in the male, and then, later, to be acquired by the female, until in
many cases the two sexes become again indistinguishable.