SEXUAL DIMORPHISM
I. Invertebrates: formation of the male.--Primitivity
of the female.--Minuscule males: the bonellie.
--Regression of the male into the male
organ: the cirripedes.--Generality of sexual
dimorphism.--Superiority of the female in
most insect species.--Exceptions.--Numeric
dimorphism.--Female hymenoptera.--Multiplicity
of her activities.--Male's purely sexual rôle.--
Dimorphism of ants and termites.--Grasshoppers
and crickets.--Spiders.--Coleoptera.--Glow-worm.
--Cochineal's strange dimorphism.
I. Invertebrates.--At a moment fairly undecided in the general
evolution the male organ specializes into the male individual.
Religious symbolisms may or might have been intended to mean this.
The female is primitive. At the third month, the human embryo has
external uro-genital organs clearly resembling the female organs. To
arrive at complete female estate they need undergo but a very slight
modification; to become male they have to undergo a considerable
and very complex transformation. The external genital organs of
the female are not, as has been often said, the product of an
arrested development; quite the contrary, the male organs undergo a
supplementary development, which is moreover useless, for the penis is
a luxury and a danger: the bird who does without it is no less wanton
thereby.
One finds general proof of the female's primitivity in the extreme
smallness of certain male invertebrates, so tiny indeed that one
can only consider them as autonomous masculine organs, or even as
spermatozoides. The male of the syngames (an internal parasite of
birds) is less a creature than an appendix; he remains in constant
contact with the organs of the female, stuck obliquely into her side,
and justifying the name "two-headed worm" which has been given to this
wretched and duplex animalculus. The female bonellie is a sea worm
shaped like a sort of cornucopia sack fifteen centimetres in length:
the male is represented by a minuscule filament of about one or two
millimetres, that is to say about one-thousandth her size. Each female
supports about twenty. These males live, first in the œsophagus, then
descend into the oviduct where they impregnate the eggs. Only their
very definite function clears them from the charge of being parasites;
in fact they were long supposed to be parasites, while men sought
vainly for the male of the prodigious bonellie.
Side by side with males who are merely individualized sexual organs,
one sees males who have lost nearly all organs save the male organ
itself. Certain hermaphrodite cirripedes (mollusks attached by a
peduncle [stalk]) cling as parasites to the coat of other cirripedes:
whence a diminution of volume, a regression of ovaries, abolition of
nutritive functions; the stalk takes root in the living, nourishing
milieu. But one organ, the male one, persists in these diminished
cirripedes, and takes on enormous proportions, absorbing the whole
of the animal. With only a slight further change one would see the
transformation of male into male organ completely accomplished, as one
does, moreover, in the hydraria. Become again an integral part of an
organism from which it had formerly separated to become an individual,
the male merely returns, to its origins and clearly certifies what they
were.
The bonellie, which is one of the most definite examples of dimorphism,
is also an example of the singular feminism which one normally finds in
nature. For feminism reigns there, especially among inferior species
and in insects. It is almost only among mammifers and in certain
groups of birds that the male is equal or superior to the female.
One would say that he has slowly attained a first place not intended
by nature for him. It is probable that, relieved of all care, after
the fecundation, he has had more leisure than the female wherein to
develop his powers. It is also possible, and more probable, that
these extremely diverse cases of resemblance and dissemblance are due
to causes too numerous and too varied for us to seize their logical
sequence. The facts are obvious: the male and the female differ nearly
always, and differ often profoundly. Many insects vulgarly supposed
to be different species are but males and females of one race seeking
each other for mating. It needs some knowledge to recognize a pair of
blackbirds, the male black all over, and the female brown-backed with
grey throat and russet belly.
While hermaphrodism demands a perfect resemblance of individuals--save
in cases like the cirripedes, where there is a male supplementary
parasite--the separation of the sexes leads, in principle, to
dimorphism, the rôle of the male, his modes of activity differ from
those of the female; a difference found also among dioic plants. Hemp
is a well known case, although the taller shoots which the peasants
call male are in exact contrary, the females. The small garden-loving
nettle has two sexes on the same stalk; the greater nettle, found in
uncultivated land, is dioic: the male stalk has very long flopping
leaves and flowers hanging along the stem; the leaves and flowers
of the female stalk are short and stand almost upright. Here the
dimorphism is not in favour of the female, but impartial.
Of insects the female is nearly always the superior individual. It is
not this marvellous small creature, nature's divergent and minuscule
king who offers us the spectacle of the bilhargie, spearwort, whereof
the female, mediocre blade, lives, like a sword sheathed in the hollow
stomach of the male. This timid life and its perpetual amours would
horrify the bold female scarabœa, adroit chalicodomes, cold wise
lycoses, and proud, terrible, amazonian mantes. In the insect world the
male is the frail elegant sex, gentle and sober, with no employment
save to please and to love. To the female the heavy work of digging, of
masonry, and the danger of hunt and of war.
There are exceptions, but found chiefly among parasites, among the
degraded, like the xenos which lives without distinction upon wasps,
coleoptera, and neuroptera. The male is provided with two large wings;
the female has neither wings, feet, eyes, nor antennæ; is a small worm.
After metamorphosis the male emerges, flies a little, then returns to
the female who has remained inside the nymphal envelope, and fecundates
her in her wrappings.
Other exceptions, this time normal, are furnished by butterflies, that
is to say by a sort of insect which is very placid, and which, at least
in the winged form, is addicted neither to hunting nor to any trade
or business function. One gives the name "psyche" to a very small
butterfly which flutters out rather clumsily in the morning; it is
the male. The female is a huge worm, fifteen times as long, ten times
as fat. The lovers are in the proportion of a cock to a cow. Here the
feminism is wholly ludicrous. There is the same disproportion in the
mulberry bombyx, of which the female is much heavier than the male; she
flies with difficulty, a passive beast who submits to a fecundation
lasting several hours; likewise in the autumn butterfly, cheimatobia,
the male sports two pairs of fine wings on a spindle body, the female
is a gross fat keg with rudimentary wings, incapable of flight; she
climbs difficultly into trees on whose buds her caterpillar feeds
itself; in the case of another butterfly which one calls, absurdly,
the orgye, the male has all the characteristics of lepidoptera, the
female is almost wingless with a heavy and swollen body and a carriage
about as pleasing as that of a monstrous wood-louse; there is the same
disproportion in the graceful, agile and delicate liparis, known as the
zig-zag because of his wing-markings; he would hardly discover his mate
without aid from instinct, she being a whitish beast with heavy abdomen
ruminating motionless in the tree-bark. Neighbouring species, the monk,
the brown-rump, the gold-rump show hardly any sexual differences.
Numeric dimorphism follows dimorphism of mass; the family of one sort
of butterfly of the Marquesas Islands is composed of one male and of
five females all different, so different that one long supposed them
distinct species. Here the advantage is obviously on the side of the
male lord of this splendid harem. Nature, profoundly ignorant of our
sniveling ideas of justice and equality, vastly pampers certain animal
species, while showing herself harsh and indifferent to others; now
the male is favoured, now the female, upon whom the greatest mass of
superiorities is heaped, and upon whom likewise all the cruelties and
disdains. The hymenoptera include bees, bumble-bees, wasps, scolies,
ants, masons, sphex, bembex, osmies, etc. The place of these among
insects is analogous to that of the primates or even of man among
mammifers. But while woman, not animally inferior to her male, remains
below him in nearly all intellectual activities, among the hymenoptera
the female is both brain and the tool, the engineer, the working-staff,
the mistress, mother, and nurse unless, as in the case of bees,
she casts upon a third sex all duties not purely sexual. The males
make love. The male of the tachyte, a sort of wasp rather like the
sphex, is about eight times smaller than the female, but he is a very
ardent small lover, marvellously equipped for the amorous quest; his
citron-coloured diadem is made of eyes, is a girdle of enormous eyes, a
lighthouse whence he explores his horizon, ready to fall like an arrow
upon the loitering female. When fecundated, the she-tachyte constructs
a cellular nest which she packs with the terrible mantis, of whom
she is the always victorious enemy; for knowing by incomprehensible
instinct whether she is about to lay a male or a female egg, she
augments or diminishes, according to its sex, the larder for the larvæ
the tiny male is allotted a dwarf provision.
The male hornet is notably smaller than the female, and the neuter
hornet still smaller. The male pine lophyr is black, the female
yellow. The male of the chalicodome or mason-bee is russet, the far
more beautiful female is a fine velvety black with deep violet wings.
While the male loafs and bumbles she artfully and patiently rears the
big-domed clay nest where her offspring pass their larvæ days. This bee
lives in colonies but the labour is individual, each doing her work
without bothering about that of her neighbour, unless it be to rob her
or spoil her construction, as in a civilization not unknown to us. The
female mason is armed, but by no means aggressive.
In many hymenoptera only the female carries the sword, as in the case
of the gilded wasp, gold-striped over blue or red, who can project a
long needle from her abdomen; the female philanthe, who is carnivorous,
while the puerile unarmed male lives upon flower-pollen. Not
disdaining this natural dessert, the female philanthe will attack the
nectar-loaded bee with her great dart, stab him and pump out his crop.
One may see the ferocious small animal knead the dead bee for half an
hour, squeeze him like a lemon, drink him out like a gourd. Charming
and candid habits of these winged topazes whirring among the flowers!
Fabre has excused this sadique gourmandizing: the philanthe kills bees
in order to feed her larvæ, who have, however, so great a repugnance
for honey that they die upon contact with it; it is therefore out of
sheer maternal devotion that she intoxicates herself with this poison!
All things are, in nature, possible. But it might not be unreasonable
to say that if the larvæ of the philanthe hate honey, it is because
their greatly honey-loving mother has never allowed them a drop of it.
One of the rare cases of hymenoptera where the female appears inferior
to the male is the mutille or ant-spider. The male is larger, has wings
and lives on flowers. The female is apteral, but provided with a noisy
apparatus for attracting the male's attention. The male of the cynips
of the oak-apple, the terminal cynips, has a blond body with large
diaphanous wings, the brown and black female is wingless. The male
yellow cimbex slender, and brown with a spot of yellow, is so different
from the round female with yellow belly and black head, that they were
long thought of different species.
Ants like all social hymenoptera are, as one knows, divided into three
sexes, winged males and females and wingless neuters. Fecundation takes
place in the air; the lovers fly up, join, fall enlocked, a golden
cloud which the death of the males disperses, while the females, losing
their wings, re-enter the house for egg-laying. The workers or neuters
are generally smaller, as noticeably in the great red wood-ants, who
dig their shelters in stumps. White ants or termites[1] show very
accentuated dimorphism; the female or queen having a head almost as
large as that of a bee, a belly the thickness of one's finger, long in
proportion, and growing to be fifteen times as large as the rest of
her body. This sexual tub lays continuously without any let-up at the
speed of an egg per second. The male, as in Baudelaire's vision of the
giantess, lives in the shadow of this formidable mountain of female
power and luxury. Among the termites there is not a fourth sex but a
fourth way of being sexless. There are soldiers as well as workers, the
soldiers having powerful mandibles mounted on enormous heads. All the
termite customs are extraordinary, and their conic nests reach a height
having a relation to them that a house five or six hundred metres high
would have to us.
Of mosquitoes and maringouin mosquitoes and all insects of that sort,
the females alone prick and suck the blood of mammifers. The males
live on flowers and tree-trunks. One sees them in forest alleys and
clearings, moving regularly as in army manœuvres, they are scouting,
watching for females; as soon as a male has caught one he seizes
her, and disappears up into the air where the union is accomplished.
Only the male cricket has a noise-machine, only the female a hearing
mechanism, situated in her front legs. Likewise it is the male
grasshopper who sounds. A love-call? People say so, but there is no
proof. Grasshoppers live, male and female in complete promiscuity
lined up on the tree-bark; such a quantity of music is unnecessary,
and moreover if the female grasshopper isn't deaf, she has an almost
insensible hearing. It is probable that the song of insects and birds,
if it is sometimes a love-call, is more often only a physiological
exercise, at once necessary and disinterested. Fabre, who lived all
his life among the implacable noises of the Provençal country-side,
sees in "the violin of the locust, in the bag-pipe of the tree-toad,
in the cymbals of the cacan only a means suitable to expressing the
joy of living, the universal joy which each animal species celebrates
in its own fashion."[2] Why then is the female mute? It is certainly
absurd and profoundly useless to summon, in almost uninterrupted song,
from morn till eve, a companion whom one sees seated beside one pumping
the juice out of a plane-tree; but it has perhaps not always been
so. The two sexes may have had, in the past, habits more divergent.
The plane-tree which unites them in the same feeding-ground has not
always grown in Provence. The unending song may have been useful
at a time when the sexes lived separate, and may have remained as
evidence of ancient customs. It is moreover a commonly observed fact
that activities long survive the period of their utility. Man and all
animals are full of maniac gestures whose movement is only explicable
on the hypothesis that it had once a different intention.
The female spider is nearly always superior to the male in size,
industry, activity, and means of defence and attack. We will note their
sexual habits later, but must observe here their particular cases of
dimorphism. The Madagascar she-epeire is enormous, very handsome,
black, red, silver and gold. She rigs up a formidable web in her tree,
near which one sees always a modest and puerile skein, the work of a
minuscule male keeping an anxious eye on the chance of sidling up to
his terrible mistress, and risking his wedding-death. The argyronete or
water-spider, returns the balance to the male, who is fatter, larger,
and provided with longer limbs.
The male triumphs again, and more frequently, among coleoptera. The
nasicom scarab, so called most aptly because he carries on his head a
long back-bending arched horn, has all his chest solidly armoured; the
female has neither horn nor cuirass. Everyone knows the flying-stag or
lucane (stag-beetle, bull-fly), enormous coleoptera which flies through
the summer evening buzzing like a top. He is feared for the bold
appearance of his long mandibles which branch like stag's horns and
which the uninstructed take for dangerous pincers. He is the male, his
war-gear pure ornament, as he lives inoffensively by sucking tree-sap.
The much smaller females are devoid of warlike apparatus, they are very
few in number, and it is in the excitement of searching for them that
the male, whose life is short and who knows it, whirls like a maniac,
and bangs himself into our trembling ears. Here again one divines
animals who have changed their habits more quickly than their organs.
The old pirate has kept his daggers and axes, but abandoned, no one
knows why, to vegetarian diet, he has lost all power to use them, he
is merely a stage-super. But maybe this gear impresses the female?
She cedes more willingly to this hector who gives her the illusion of
strength, that is of the male's beauty.
The glow-worm is a real worm, but a larva rather than a definitive
animal. The male of this female is a perfect insect, provided with
wings which he uses to seek in the darkness the female who shines more
brightly as she more desires to be looked at and mounted. There is a
kind of lampyre of which both sexes are equally phosphorescent, one in
the air, the male, the other on the ground where she awaits him. After
coupling they fade as lamps when extinguished. This luminosity is,
evidently, of an interest purely sexual. When the female sees the small
flying star descend toward her, she gathers her wits, and prepares
for hypocrite defence common to all her sex, she plays the belle and
the bashful, exults in fear, trembles in joy. The fading light is
symbolic of the destiny of nearly all insects, and of many animals
also; coupling accomplished, their reason for being disappears and life
vanishes from them.
The male cochineal has a long body with very delicate wings,
transparent and which at a distance look like those of a bee; he is
provided with a sort of tail formed of two silky strands. One sees
him flying over the nopals, then suddenly alighting on a female, who
resembles a fat wood-louse round and puffy, twice as stout as the
male, wingless. Glued by her feet to a branch, with her proboscis
stuck into it, continually pumping sap, she looks like a fruit, like
an oak-apple or oak-gall on a peduncle for which reason Réaumur called
her picturesquely the gall-insect. In certain species of cocides the
male is so small that his proportion is that of an ant strolling over
a peach. His goings and comings are like those of an ant hunting for
a soft spot to bite, but he is seeking the genital cleft, and having
found it, often after long and anxious explorations, he fulfills his
functions, falls off and dies.
[1] These are neuroptera or pseudo-neuroptera, but their habits bring
them noticeably near to social hymenoptera.
[2] Souvenirs entomologiques, tome V. p. 256.