SOME “COLD-BLOODED” LOVERS
The Courtship of the Crocodile—Amorous Lizards—Horned Chamæleons—A
flagellating Terrapin—The Frog that would a-wooing go—Semo musical
Frogs—Some marvellous instincts in Newts.
The measure of the vitality of animals may be estimated by their
response to stimuli; and their behaviour increases in variety and
complexity as the nervous system develops. Our interpretation of
that behaviour commonly leaves out of account the character of this
responsiveness: we are apt to see proof of intelligence in acts which
should be read as instinctive. And instinct is to be regarded as a
co-ordinated response to stimulus, independent of prior experience.
The complexity of this response stands in very close relation to the
structural complexity of the organism in which it occurs, and this
because an ever-increasing number of mechanisms and actions must be
set in motion to carry out the fulfilment of any given stimulus, as
this is traced from the lower to the higher groups of animals: till at
last we have to distinguish between movements that are merely reflexes,
and those which are “instinctive.” The latter must be fulfilled by
the former—the reflex actions are the agents of the instinctive.
Indifferent performance in either, endangers the existence of the
individual, and in some directions of the race itself.
The sexual instincts, with which alone these pages are concerned, are
primarily stimulated and sustained by internal forces, generated, as we
have already seen, by the juices of certain glands whose relation to
the reproductive system has only recently been discovered. Though not
commonly realized, and though denied by some, the sexual instincts are
the dominant factors in the animal world. Even Man himself, the lord
of Creation, knowing good and evil, cannot escape their overmastering
rule. Commonly he is by no means inclined to rebel against this control
But there be some who, in their arrogance, imagine that its overthrow
is an end to be desired. Having scaled some slight intellectual
eminence they fondly imagine this feat was accomplished by virtue
of some spiritual grace of their own cultivation, and call to their
fellow-men to emulate their example. But such preceptors are labouring
under a strange delusion: they are suffering from a disease they wot
not of, a “Disharmony,” as Metschnikoff calls it, a disease which
blinds their perception of the motive power which has given them all
that they believe themselves to have created. For these same despised
instincts are the sacred fires of our being, and when they are quenched
all that makes us human, love, ambition, and life itself will be
extinguished. If the continuance of the race be a thing to be desired
it is well that the choice should not be left to us.
Truisms are sometimes trite, and while it is a truism to say that
no race can continue which does not reproduce its kind, it is more
exact to say that, other things being equal, the race depends for
its existence, primarily, on the efficient working of the sexual
instincts. In the higher animals, the phenomena which these present are
so complex that they often assume something more than a semblance of
intelligent, purposeful behaviour. It is therefore necessary, for their
right understanding, that they should be analysed in animals lower and
lower in the scale of life till at last we come to the very simplest
types of organisms wherein instinct can be said to play a part.
The lower we descend in the scale of animal life in our survey of
behaviour during the reproductive period, the more the evidence seems
to grow in favour of the interpretation of the Sexual selection theory
adopted in these pages—the view that neither the formal displays nor
the exaggerations of colour and ornament which so commonly accompany
them, are due to female choice; a choice not necessarily conscious,
but rather to be interpreted as the final abandonment to the finest
performer of a number of suitors. On the contrary, this ornamentation,
of whatever kind, is the expression of an intensification of the gland
secretions which is manifested by the process of pigment concentration
and a consequent intensification of coloration. Hand in hand with
these developments it would appear goes an exaggeration of the normal
movements which characterize the species when under the influence
of great excitement, whether of fear or pleasure. At any rate, the
displays of gaudily coloured and highly ornamental species are commonly
more striking than those of sober hue.
On this rendering, the behaviour of Reptiles, Amphibia and Fishes, is
much more readily interpreted, and this is even truer of the more lowly
groups of animals such as Spiders, Butterflies and Beetles.
Among the Reptiles, as among the birds and beasts, the desire to
obtain territory seems to be strong. But the information to be
gathered as to their behaviour in the search for mates, and after, is
exceedingly small.
Sluggish by nature, all become animated under the stimulus of
mate-hunger, and this is especially true of the males. As one
would have expected, from what has just been said, desire is most
demonstrative in brightly coloured and highly ornamented species. But
even the dullest hued and most phlegmatic display quite surprising
agility and animation under the fever of Love. Thus among the
Crocodiles fierce battles are fought by rival males for the possession
of some coveted female: and later the victor strives to dispel the
apathy of his mate by caperings most undignified in a Crocodile. He
will twist and turn, or rather twirl, round on the surface of his
chosen pool, with head and tail raised high in air, and his capacious
barrel of a body swollen out to bursting point. These antics are
performed to the accompaniment of loud bellowings and roars heard at no
other season of the year. But more than this, an appeal is made to the
nose as well as to the eyes of his apathetic mate, for during all this
parade of love he exudes from glands in the lower jaw, and tail, an
almost overpowering smell of musk. At last, however, these antics have
their reward, for sooner or later apathy awakens into interest, and
interest ends in desire.
The Crocodile is colourless, or at least is monochromatic; not so many
of the Lizards, which rival the birds in the vividness of their hues.
With the birds the colours undergo no changes save such as are due
to the incidence of light; with the Lizards, however, the bare skin
is exposed and this can, as it were, be made to blush with all the
colours of the rainbow. Having regard to what has been said already
as to the sources of this coloration it is not surprising to note
that here also the males are the more vividly coloured whenever the
sexes differ in this particular. And further, it is among the most
vividly coloured males that most animated displays take place when the
endeavour is being made to excite the amorous instincts of the females.
The males of the genus Sitana are very brightly garnished. They possess
a large throat pouch, coloured blue, black, and red when expanded, and
this occurs only during moments of excitement, whether this is due to
fear or pleasure. And at the same time the vividness of the coloration
is greatly increased. No such secondary sexual characters are present
in the female.
A variant on the throat pouch, of a much more striking character, is
displayed by the Frilled Lizard (_Chlamydosaurus kingi_), wherein
the tongue bones have become enormously elongated so as to project
backwards on each side of the body almost as far as the base of the
tail. With them they have carried a thin fold of skin, so that whenever
the mouth is opened these bones stand out at right angles to the head
and display a circular fold of skin stretched as it were on rods; or
they may be compared to the ribs of an umbrella. The great Elizabethan
frill thus formed, is displayed only during moments of great
excitement, and the open mouth, at such times, is flushed with a vivid
red, which, contrasting with the teeth, gives a very terrifying aspect
to prospective enemies, and doubtless also proves a valuable asset as a
“secondary sexual character.”
The display of a vividly coloured mouth during moments of sexual
excitement, it may be remembered, occurs in some birds. Among reptiles
it is a common feature. A good illustration of this is furnished
by the Moustached Lizard (_Phrynocephalus mystaceus_), a native of
Southern Russia. When violently excited it raises itself on its hind
legs, curls and uncurls its tail, and opens its mouth to its widest
extent, presenting, to our eyes, a quite fearsome aspect. This effect
is immensely increased by the fact that the corners of the mouth
are provided with flanges of skin, which at this time swell up into
crescentic plates, the inner borders of which pass gradually into the
rosy lining of the mouth, thereby causing it to appear much wider
than it really is. So far this display has been witnessed only when
the animal is under the influence of fear. But since we find that
birds will make similar displays, both when under the stimulus of fear
and that of sex, we may assume, with no little degree of certitude,
that the same applies in the case of the reptiles, for the origin of
the ornaments is almost certainly to be attributed to the same gland
secretions which produce the secondary sexual characters of birds and
beasts.
This, however, is no mere assumption, for we have some positive
evidence as to the association of bright coloration with “courtship,”
which has been furnished by Mr. Annandale, a naturalist of long
experience and having a first-hand acquaintance with tropical life.
He has given us a lively description of the courtship of the Malayan
Lizard (_Calotes emma_). “The males,” he says, “are very pugnacious,
and change colour as they fight. At the time of courtship a curious
performance is gone through by the male, the female remaining concealed
in the foliage hard by. He chooses some convenient station, such as a
banana-leaf, or the top of a fence, and advances slowly towards the
female. His colour is then pale yellowish flesh colour, with a
conspicuous dark spot on each of the gular pouches, which are extended
to their utmost. He stands upright, raising the fore-part of the body
as high as possible, and nodding his head up and down. As he does so
the mouth is rapidly opened and shut, but no sound is emitted. When he
is driven away, caught, or killed, the dark spot disappears entirely
from the neck.”
[Illustration: Plate 30.
Photo by W. Saville-Kent.
THE BEARDED LIZARD.
Paring moments of excitement the Bearded Lizard opens the mouth widely
displaying a vividly coloured interior.
Face page 166]
Normally sluggish, the Lizards display, it will have been remarked, a
quite surprising degree of animation when maddened by mate-hunger. Some
exhibit a considerable degree of pugnacity. In _Anolis carolinensis_,
for example, when two males meet they face one another, bob the head up
and down two or three times, expand the throat pouch, lash their tails
from side to side, and then, worked up to the requisite degree of fury,
rush at one another, rolling over and over and holding firmly with the
teeth. The conflict generally ends in one of the combatants losing his
tail, which is eaten by the victor.
The Chamæleons include among their number species which have developed
quite formidable horns, recalling those of the Rhinoceros or, better,
of the extinct Arsinoetherium, since they are placed side by side
instead of one behind the other. In Owen’s Chamæleon there are three
such horns, two on the forehead and a median horn on the snout, and
these are borne only by the males.
The marvellous play of colour which many Lizards display is commonly
attributed indifferently to “protective coloration” and to “sexual
selection.” It is unlikely that both have played equally important
parts in their development. If the case of certain of the Geckoes alone
is taken, then there would seem to be no doubt but that “Natural
Selection” was the agent which had determined their elaborations
for protective purposes, and in such and similar cases this may be
largely true. But the material which “Natural Selection” has worked
upon has been furnished by the secretions of the sexual glands to
which reference has so frequently been made already. These seem to
possess a very marked tendency to contain an excitant which promotes
the formation of intense pigmentation, or an excess of tissue which
may assume the form of weapons of offence, or of excrescences in the
form of spines, or other ornamental features. Animals in whom this
tendency to pigmentation and ornament has developed must, so to speak,
obtain a licence from “Natural Selection” if they are to retain it.
That is to say, if such ornament whenever it appears makes the wearer
conspicuous to its enemies, or hampers it in escaping therefrom, or in
fulfilling the ordinary avocations of life, then its further progress
will be inhibited, or the wearer will be exterminated. But the tendency
to produce colour, a by-product of the sexual gland secretions, may
incidentally serve to afford it a protective garb, and in this event
its further elaboration in the required direction is assured.
In certain abnormal, sexually poisoned individuals among the human race
it is well known pleasure is derived from flagellation. There is but
one instance known to me where this obtains as a normal accompaniment
of desire among the lower animals, and this occurs in one of the
Painted Terrapins (_Chrysemys picta_), whose finger-nails are produced
into long, whip-like ends. I had the good fortune to witness their use
one day when in the Reptile House at the Zoological Gardens in London.
The unusual activity of a male of this species was the first thing to
attract attention to his movements. Watched more closely, he was found
to be dodging a female and making frantic efforts to swim round so as
to oppose her path. This done, he closed up and immediately commenced
to apply the bastinado to her head. The movements were so rapid that
nothing more than a blurred image of these strange whips was visible.
As soon as she escaped his attentions, he set about circumventing her
again, and again succeeded: and this most extraordinary performance was
repeated many times during my watch.
Turning to the Amphibia, the descendants of that stock which must be
regarded as the ancestors of the Reptiles, the version of the sexual
rôle which is adopted in these pages, that “Sexual Selection” in the
older, Darwinian sense, does not exist, finds further support.
Among the tailless Batrachians—the Frogs and their kind—there is no
“display” immediately preceding the act of pairing. The males seize
upon the females and hold them in a close embrace which lasts for a
very prolonged period, covering many days or even weeks, until the
extrusion of the eggs, which he impregnates by successive emissions
of the fertilizing element. What controls the orgasm no one has yet
succeeded in discovering, but this is an important point, for it is
essential that the seminal fluid should not be emitted until the moment
the eggs are set free. The pairing act is here purely instinctive, as
is shown by the fact that if a Frog in embrace be removed and replaced
on some inanimate body, this will be treated as though it were a female.
With the tailed Batrachians—the Newts and Salamanders—the male
commonly executes a very animated display which is followed by
behaviour of a quite remarkable character. The display, which is always
associated with vivid coloration, or the development of fin-like
frills along the back, takes the form of amorous writhings and other
gesticulations. At times he will hit his mate with his snout, and
at others he will simply rub sides with her, as if to entice her
to respond to his advances. These evolutions may be followed by an
amplexus, an embrace. In some species, however, these performances are
followed by behaviour which leaves one gasping with astonishment.
To begin with, there is no act of pairing, no coitus, but the male
discharges a number of conical or bell-shaped “spermatophores,” each of
which is crowned by a bunch of spermatozoa, the male germs necessary
to ensure fertilization of the ova. These spermatophores adhere to
the bottom of the stream, and are gathered up by the female, either
directly, by placing herself in such a position that they can be seized
by the lips of the genital opening, or by seizing the spermatophore,
with its fertilizing germs, between her hind legs and pressing it
home! The more one contemplates this extraordinary proceeding the more
one marvels at the evolution of a departure from the normal sexual
relations so inconceivably strange. Here one sees the purpose of the
aphrodisiac in its true light. But for these facts it would have seemed
certain that its primary object was to enable the male to relieve
desire and at the same time to accomplish its end—the fertilization of
ova—without undue waste. And this, in all the cases so far discussed,
is possible only when the female has become inflamed with a like
desire for coitus. But here the male finds relief, without more ado,
by depositing the precious germs upon the ground. The display then is
indeed to serve as an aphrodisiac. For the continuation of the race now
rests entirely on the female. Any defect in the orderly working of her
sexual appetite means the waste of the spermatozoa and the failure to
effect fertilization. We cannot suppose that there is any realization
of these facts, or any deliberate action on her part, but rather that
she derives pleasurable feelings from the necessary passage of the
spermatophore, which, probably, she recognizes by its smell.
The statement that the Frogs and their kind dispense with a display
requires some qualification. For in the first place they, like their
tailed relatives the Newts, develop secondary sexual characters, but
these are of a quite peculiar kind. Among the Newt tribe, as has been
mentioned, these characters take the form of frills and crests and
vivid colours. They are intended to stimulate through the sense of
sight, and arouse emotion, as a city is beflagged to welcome those it
may delight to honour. The Frog tribe appeal to the musical sense, even
though that music be of a barbaric kind. But, it would seem, when once
the errant females have been drawn to the spot chosen by the males, no
further aphrodisiac is used, the male simply seizing upon the female
nearest at hand and, having once embraced her, she is not released
again until the eggs have been extruded and fertilized. To maintain
his hold, the forearm is often excessively muscular, while one or more
of the fingers may be armed with pads. In some cases, as with the
Himalayan _Rana liebigi_, the inner side of the arm and each side of
the breast are studded with small conical spines. But the absence of
ornament in these cases, as with such of the Newts where there is no
amorous display before embrace, is significant.
And now, as touching the musical performances of these troubadours.
These commence in the early spring. With many species, as with our
Common Frog (_Rana temporaria_) nothing more than loud croakings are
attained. But with others this “music” is enormously increased in
volume by resonators in the form of air-sacs or wind-bags. We may
surely, with some show of certainty, liken this “music” to the song
of birds, and assign its primary purpose to the same cause—a device
to advertise their presence to wandering females seeking mates. That
birds sing after mates have been found, and later, is no doubt due
to a general feeling of “fitness,” which finds expression in what
has become the usual mode for such emotional states. Most people
must have heard the spring concerts of our Common Frog; but these
are incomparably surpassed in volume by the Edible Frog and the Bull
Frog, which are provided with large, globular, inflatable, air-sacs in
the throat, serving as voice-resonators. Such performances, however,
are mere bawlings compared with some other species, which mew like
cats, or bark like dogs. The most famous of all is the Brazilian
“Ferreiro” or “Smith” (_Hylodes faber_), whose voice is one of the
most characteristic sounds to be heard in Tropical South America.
“Fancy,” says Dr. Gadow, “the noise of a mallet, slowly and regularly
beaten upon a copper plate, and you will have a pretty good idea of
the concert given generally by several individuals at the same time
and with slight variations of tone and intensity.” When seized, the
performer utters a “loud and shrill, most startling cry, somewhat
similar to that of a wounded cat.” Another, a Paraguayan species,
_Phryniaxus nigricans_, at the breeding season, utters a call note
which consists of two clear, musical “rings,” followed by a long
descending “trill” like that of our British Greenfinch. But, it is to
be noted, both sexes in this case perform.
The period of sexual activity with perhaps the majority of animals
is intermittent and extends over but a short period annually; with
others potency is continuous, at least with the males, though desire
becomes clamant only when aroused by external stimuli. But whenever
this condition be aroused it invariably finds expression in exaggerated
movements or vocal demonstrativeness. It uses the normal channels of
expression, in short, but intensifies them. Now this period of sexual
activity represents the maximum of “fitness” in animals, and it is not
surprising, therefore, to find that when the barometer of vitality
stands high some approach to the maximum of activity is indicated. In
many birds this is revealed in song, though the earlier stimulating
cause is absent. Among the cold-blooded frogs the same obtains. In the
Edible Frog (_Rana esculenta_), for example, the males, which “are
great musicians,” remarks Dr. Gadow, “go on singing for sheer enjoyment
not only during the pairing time, but throughout the months of June and
July. Warm, moonlight nights are the favourite times for the concert,
which takes place in the water, beginning at sunset and continuing till
early dawn. A few individuals utter a single note, ‘gwarr-oo-arr’ or
‘coarx’ but these are only preliminaries. The precentor ... begins with
a sharp-sounding ‘brekeke’ and this is the signal for all the others
to chime in with the same note, varied with all sorts of other sounds,
bass, tenor and alto, each performer filling its resounding vocal sacs
to bursting size, and these bags then look as if they acted as floats.
When there are several hundred of these sociable creatures the din is
continuous, and may be heard more than a mile off.”
From what has been said of the Amphibia, and especially of the
Newts, it would seem that, among the land vertebrates at any rate,
the sexual instincts in this lowest or simplest form are satisfied
with the discharge of the germinal products. Many, however, have
advanced a stage further and reveal the rudiments of that instinctive
care for offspring which develops to higher and higher grades as we
ascend in the animal kingdom, till at last, in the human race, where
the offspring is desired for its own sake, we ascend to the highest
plane of all. The varied means of expression which these rudimentary
instincts take in the Amphibia have already been discussed in “The
Infancy of Animals,” which preceded this present volume, and hence no
more need be said on this head in these pages.