As a rule, among these animals the males are smaller than the females. In the case of the Argonaut there is a yet more striking difference, for the female possesses a very beautiful shell in which she carries her eggs. This remarkable cradle, translucent and beautifully sculptured, she attaches to her person by means of a pair of arms which are expanded to form great lobes, almost but not quite completely covering the shell. The earlier naturalists believed that this shell served as a boat, and that the lobated arms were spread as sails! This supposed fact naturally caught the fancy of the poets, who seized upon it to point a moral and adorn a tale. Byron celebrated these imaginary feats of seamanship in the familiar lines:

and Pope bids us:

Sir Richard Owen years ago, however, dispelled these pretty fancies, though the facts are surely as wonderful as the fables they have replaced. They afford, too, one of the most striking secondary sexual characters to be met with among the Mollusca; nowhere else, indeed, among the members of this group is so strange a cradle to be met with.

But little, unfortunately, is known of the behaviour of these animals, which are by far the most active of the Mollusca, and which also display no small degree of intelligence. Their eyes, which are of great size and complex structure, are undoubtedly far more effective organs of vision than are possessed by any other Molluscs. It is possible, therefore, that the sexes discover one another by sight; and it is certain that something in the nature of a “Courtship” takes place. The majority of the species, also, possess the most extraordinary powers of changing their coloration, especially during moments of great excitement. The magnificence of the hues which succeed one another, like a series of variegated blushes suffusing the whole body, may be one of the weapons in the armoury of Cuttle-fish love-making. In how far the “courtship” of the Cuttle-fish resembles that of terrestrial animals, however, is a matter on which at present nothing is really known. That even the comparatively sedentary species, like the Octopus, seize upon and hold territory is very improbable, for there is no need of such landed estates, inasmuch as the offspring are not tended and fed by the parents—this would indeed be a laborious task in the case of some of the “Squids” which lay between thirty thousand and forty thousand eggs! Having regard to the fact that the records of the reproductive habits of the Octopus tribe date back to the time of Aristotle, more than two thousand two hundred years ago—for he first drew attention to the hectocotylized arm—it is curious that so little has been gleaned during this vast space of time.

There are facts in regard to the sexual relationships of some of the Snails that are in nowise less remarkable than those just related of the Octopus tribe. Unlike the Octopuses, the Snails are hermaphrodite, nevertheless sexual congress takes place as with unisexual species: the eggs of the one being fertilized by the spermatozoa of the other. During this process the orgasm of the sexual act appears to be brought about by stabbing one another by means of a little dart formed of carbonate of lime, the dart burying itself in the flesh and apparently promoting a pleasurable, tingling sensation in the course of its journey. Speedily, no doubt, it becomes absorbed, the material being then available for the formation of a new dart.

This remarkable instrument, which is known as a “Love-dart,” or Spiculum amoris, assumes a different form in each species in which it occurs. In some the shaft is ridged like a bayonet, as in the case of the Garden Snail, in others the form assumed is that of an awl. These darts are formed within a special receptacle, or “dart-sac,” but so far no explanation as to the origin of these remarkable structures has even been hinted at. They do not seem to have been derived by the modification of some pre-existing organ serving a different function, as wings, for example, are derived from walking limbs, or as lungs are derived from air-sacs. Their origin is as mysterious as their use: for they are not found in all Snails, though they occur in one or two Slugs—which are degenerate Snails. But no other Molluscs save the Snails and one or two of their immediate allies are so armed.

The hermaphrodite conditions of these animals, as with other Mollusca in like case, present some knotty points for consideration, and especially in regard to the problem of sex-attraction. Where each individual is as much male as female, which is the dominating factor in desire, the maleness or the femaleness? Though each individual contains both ova and sperm cells, probably these ripen at different times, to avoid danger of self-fertilization. In this case the sex impulses are on the same footing as in the case of animals wherein the sexes are not thus combined. That is to say, the individual which is for the moment only potentially male mates with another for the moment only potentially female. But this being so, how does each discover the condition of the other?

Many of the Snails, like Helix nemoralis, are gaily coloured. Are these hues, these bands of black and yellow, the product of “sexual selection”—the outcome of a process of selection from among the most conspicuously coloured individuals as postulated by the Darwinian theory of Sexual Selection? If so, then this choice must be regarded as a periodic recurrence coinciding with the period during which the individual is dominated by its female attributes. In due course it becomes, for the time, a male, and may find itself rejected, owing to a lack of intensity in its coloration, or, on the other hand, it may vanquish a rival by its very splendour. Each, in short, would help materially in this process of beautification. If the choice of mating for it is this rather than a choice of mates—proceeds on these lines, the bright coloration of the members of this species becomes easy to understand. But does it? It is more than doubtful whether the eyes of Snails are sufficiently good to distinguish the coloration of their neighbours’ shells, or for the matter of that of their own, for their eyes being carried on long mobile stalks, they should have no difficulty in contemplating their own charms. And what of Snails of more sober hues? It seems highly probable that here, as in so many cases, scent is the selecting factor, and the coloration is an “accidental” feature. That the colour of the shell plays no such part as that just postulated may be gathered from the evidence afforded by many marine species, whose shells, though conspicuously marked, are, during life, completely enveloped and concealed by the all-investing, fleshy mantle. In like manner the exquisite beauty in the form and sculpturing of the shell which so many species exhibit, are characters which cannot be regarded as due to sexual selection.

As touching the danger of self-fertilization to which reference has been made. That this is real is shown by the fact that the ova and spermatozoa are rarely ripe in one individual at the same time. However, among the pulmonata, or air-breathing gastropods, it seems to have been established that self-fertilization can, and does, occur. That in some species, at any rate, where cross-fertilization, for some reason, is impossible, the individual thus isolated can store up its own spermatozoa to be used in fertilizing its own eggs. But the fact that this rarely happens is testimony enough that such occurrences are inimical to well-being.

The Lamellibranch, or bivalve Mollusca, e.g., Oyster, Mussel, and Cockle, afford valuable evidence as to excrescences and extravagances of growth which appeal to our eyes as ornamental, and therefore likely to be due to the influence of sexual selection. And this because such ornamentation is a very conspicuous feature among these animals. Yet, save in a few cases, locomotion is impossible, and sight is wanting. Light-distinguishing organs, and therefore eyes, are possessed by some, but in no case probably are they strong enough to appreciate form. Even if they did, such revelations of beauty would play no part in mate selection from among the most ornamental; for these creatures are commonly fixed throughout life in one position, often, indeed, buried in mud or sand. Some move laboriously: a few, like the Cockles and Pectens, swim by rapidly opening and closing the shell. The Pectens are brilliantly coloured, not only as regards the shell, which is also beautifully sculptured, but the foot also is of a vivid scarlet, and the Pecten have numerous minute eyes. But the Cockles and Mussels possess like attributes as to colour and sculpture, yet they are blind. More to the point is the fact that these animals do not mate after the fashion of higher animals, but the males, where the sexes are distinct, discharge immense quantities of spermatozoa into the water, and these find their way to the ova of the female through the action of the inhalent currents set up by the animal for the purpose of drawing in fresh supplies of water containing food and oxygen. There are no “secondary sexual characters,” that is to say, that even where the sexes are separate, and many, like the Oysters, are hermaphrodite, they are externally indistinguishable. Nevertheless, many, as has been already remarked, have shells of great beauty. As, for example, the giant Tridacna and the strangely spinous valves of the “Thorny Oysters” (Spondylidæ).

The fact that the Lamellibranch, or bivalve molluscs, are far less numerous in point of species than the univalve tribes is accounted for by the fact that in the first place they are of necessity aquatic, and in the second their means of locomotion is extremely limited. Some few species swim spasmodically: some crawl: many are incapable of movement when once the motile larva settles down and the shell-bearing adult stage is attained. Such species can extend their range only by means of larval wanderings. Enormous numbers, millions, of young have to be produced and set adrift each year by every adult in the community, and yet but a few of each brood can ever attain to maturity. Life, for such species, must be a dull, monotonous business: the only opportunity for excitement is that which is preliminary to being eaten, and the only purpose in life is to be eaten. But happily Oysters don’t think. They and their kind are simply semi-conscious living things, responding mechanically to stimuli. Any approach, then, to beauty, either of form or coloration, or both, must be regarded as due to innate, inherent changes in the germ-plasm affecting the parts so made conspicuous: the only form of selection to which such “ornaments” can be subjected is Natural Selection. If, and when, such ornaments penalize their possessor either by their cumbrousness or their conspicuous characters, or by increasing the difficulty of feeding or distributing offspring, then the further development of such excrescences is checked by the death of all individuals which have passed the bounds of endurance in this respect.

Sex, and all that appertains thereto, in short, is in these creatures reduced to its lowest terms. There are not wanting, to-day, both men and women, who affect to believe that all would be well for the human race could a similar slowing-down, or strangulation, of the sexual instincts be brought about. Such blind leaders might profitably contemplate the Oyster: but such contemplation, to be profitable, requires intelligence of a higher order than these protagonists of folly appear to possess.

In justice to Darwin it should be remarked that he himself fully realized, and carefully points out, the inconceivability of the application of the Sexual Selection theory to the Mollusca. In commenting on the beauty of colour and shape which many species display, he remarks: “The colours do not appear in most cases, to be of any use as a protection; they are probably the direct result, as in the lowest classes, of the nature of the tissues1: the patterns and the sculpture of the shell depending on the manner of growth.” Just so: and this is surely the fundamental explanation of ornament, using this term in its widest sense, everywhere in the Animal Kingdom. The peculiarities and eccentricities of behaviour, which occur among the higher groups, act as “aphrodisiacs” to hasten reproduction because this confers an advantage, the earliest to produce offspring—so soon as the conditions for their nurture are favourable—having the best chance of survival. Premature sexual activity is checked by the death of the offspring.

It has been contended that the hermaphrodite condition represents the primitive mode of reproduction among the multicellular animals—that is to say, all animals above the level of those whose bodies are composed of but a single cell, or particle, of protoplasm—but this view is probably erroneous, and the hermaphrodite state must be regarded as a secondary condition, a later innovation.

More remarkable are the facts concerned with that singular form of reproduction known as parthenogenesis, or the production of offspring by virgin females. This is undoubtedly a degenerate sexual condition occurring as a normal mode of reproduction, among the microscopic “Rotifers,” e.g. the “Wheel-animalcule,” Crustacea, and Insects, and in varying degrees of intensity.

The most familiar instances of Parthenogenesis are furnished by the Hymenoptera, and notably by the Bees and the Aphides.

There are certain cases among the Rotifers where no males have ever been found, and it is possible that they have become entirely suppressed, but in every other case the periodical advent of males is an absolute essential for the continuation of the race. Perhaps the least degenerate of these types are the Bees, wherein we meet with well-developed, highly-organized males and females, which, in their sexual relationships, are perfectly normal. But in the fulfilment of the mating instincts in these insects, a most amazing sequence of events is revealed such as are without parallel in the rest of the Animal Kingdom. The story has been charmingly told already by Maeterlinck, in his delightful “Life of the Bee,” and it has been told again by Tickner Edwardes, with less of poetry, perhaps, but still fascinatingly: and it must be told again now, but in a condensed fashion.

Briefly, a community of hive-bees harbours both male and female individuals only for a very short space. During the greater part of the year it consists only of a vast concourse of infertile females, the daughters of one mother; the “queen” of the hive. The males of that hive are the brothers, not the fathers, of the workers, as some have supposed, and their sojourn there is brief. To gain a clear idea of the facts in regard to the life-history of these insects it is necessary to trace some of the incidents which lead up to the manner in which the population of the hive is regulated, and its continuance ensured. These may well begin with the time when the number of the inhabitants consonant with the well-being of the hive has reached its limit. This occurs during the early part of June, when the queen leaves the hive, accompanied by several thousands of her daughters; they settle at some distance from their late abode in a “swarm” for the purpose of founding a new colony. Here we may leave them. The house just vacated is, however, not entirely deserted. A few of the inhabitants, the infertile sexless workers, degenerate females—degenerate so far as the power of reproduction is concerned at any rate—are left behind, and there remain also in their cradles a variable number of unhatched queens, and drones or males. One of these potential queens and the males now speedily emerge, and for a day or two remain within the seclusion of the hive, feeding upon the honey stored in the combs.

The males are the first to leave, making daily excursions abroad in the search for mates. They display in this a very leisurely behaviour, rising late and not venturing out till the day is well aired. Returning early in the afternoon with sharpened appetites, they feed to repletion and soon fall asleep.

In about three days, however, the young queen ventures abroad, timidly at first, to stretch her wings in the sunshine. She is preparing for the great moment of her life, the nuptial flight. So far, though drones may swarm on every side of her, no sign of recognition is given, nor do the males evince any consciousness of her presence. She behaves warily and demurely throughout. Her first excursions abroad are very brief; they are not so much trial flights, apparently, as efforts to locate the exact position of the hive in relation to the outer world. To this end the flights are rapidly extended in ever-widening circles, till at last, with lightning speed, she makes for the blue sky, to return to the gloom of the hive almost immediately after. During all this time the stimulus of sexual desire has been gathering force, and now, being no longer controllable, she darts off, and up into the sky; almost at once she is recognized by the swarms of males from neighbouring hives, some thousands in number, which for days have been seeking this event. Instantly they give eager chase, mounting after her higher and ever higher. But as they ascend so their numbers decrease. Some, the feeble, the ill-fed from impoverished hives, are speedily left behind; many endure to the end, but only one secures the prize, and this great moment of his life is also his last, for the fact of impregnation is no sooner completed than Death claims him. He falls earthwards, as if struck by lightning, and in his fall the intromittent organ is dragged from his body, to be removed by the survivor of this mad flight, on her descent.

She leaves a bride and returns a widow, filled with murderous intentions. There are captive queens in the hive, and she can tolerate no rivals. So soon as she has removed from her person the embarrassing souvenir of her nuptial flight she makes for the Royal cells. Accompanied by attendant workers she proceeds to tear off their waxen coverings and put their occupants to death with a thrust of her stiletto. No sooner is the work of execution over than the dead bodies are seized by the workers and borne out of the hive. This awful task is soon over, however, and henceforth for four or five long years she remains a prisoner within the walls of her own palace. Craving neither the air nor the light of the sun, she will die without once having sipped the nectar from a flower. And during all this time, save during the winter sleep, her sole duty is to produce sons and daughters. In the prime of her maternity she may lay as many as three thousand eggs a day. But strangely enough the number of eggs produced is determined for her by the workers, who are the real rulers in this constitutional state. By varying the amount and quality of the food they give her they can increase or check the number of eggs produced; while even the sex of the resultant larva is apparently also under their control.

During that brief, weird honeymoon in the clouds she received a store of spermatozoa, the fertilizing male germs, sufficient for all the eggs she can ever lay, and they may amount to nigh on a million. Incredible as this may seem, their purpose is yet more so; for they are destined to be expended solely in the production of female offspring doomed for the most part to perpetual spinsterhood. One youngster in ten thousand may attain to a higher state, may, if Fate wills, become a queen and mother. And because of this need for mothers to carry on the race, this extraordinary state of affairs has been brought about. All is under the control of her daughters—the spinster-workers. As she proceeds on her rounds of egg-laying an attendant crowd waits upon her, controlling her actions by gentle caresses. As she passes from cell to cell, the cradles of the young that are to be, she thrusts down her abdomen and lays an egg in each. The cells destined to produce the workers are the smallest, those for drones are larger, and those for queens are largest of all, and the walls are formed of pure pollen, not of wax as are those of the workers and drones. But it would seem that she never lays an egg in any of the last named. The sight of a queen-cell rouses her to fury. These cells, then, are filled by the workers, who remove the requisite number of worker—eggs from the cells in which they were laid and deposit them in the queen-cradles. The larvæ at hatching, and for the first three days of life, differ in no wise from their sisters around them. Their Royal state is determined solely by the food which is administered to them. This consists of “bee-jelly,” which is furnished in abundance: a white, shining liquid, regurgitated by the ever-zealous nurse-bees. These superfed babies cease feeding at about the fifth day, and each spins for herself a silken vestment in which to undergo the pupal state. This done, the door of each cell is sealed up with pollen. During the following sixteen days strange transformations take place: the queen that is to be is taking shape. But the cradle now becomes a prison, for at the end of the sixteenth day each of the four or five young queens begins to clamour for release. But this cannot be, for such as succeeded in emerging would immediately be slain by the reigning queen. A small hole is bored through the roof of the cell, and through this each is fed, and a close guard is kept night and day to ensure that they shall not emerge till the moment is ripe. Soon each captive begins to gnaw away the roof of her prison chamber, and as rapidly more material is placed by her guards on the outer surface. Not until the old queen leaves the hive with thousands of her daughters to “swarm” and found a new colony will freedom be allowed; and then only to one. The rest must remain till the new queen either also “swarms,” or returns from her nuptial flight, and in this case all will be slaughtered in their cramped quarters, unable to resist.

But what of the drone? He, as has already been mentioned, is reared in a larger cradle than that of his sisters—save such as are destined to be queens—and for the first three days of his life is fed on “bee-milk” of a special kind and more generous quality than that of his worker—sisters, the Cinderellas of the hive; but this generous diet is diminished at the end of three days, when a mixture of honey and pollen is given him. In about three weeks or rather more he emerges, a great, lazy drone, and for a fortnight more he wanders about the hive alternately soliciting bee-milk from his sisters and helping himself to honey from the comb, and when full to repletion he seeks some snug corner in which to sleep off his surfeit. In due time, however, he ventures abroad, his hour is at hand. He takes his daily flights abroad in search of a mate, returning home early in the afternoon for his rations, being too indolent or too stupid to draw nectar from the flowers for himself. Thus for many days he and his brothers disport themselves in riotous living, till one or other of them attains the end for which he was born; and after a few delirious moments drops earthwards a mutilated corpse.

But so far only a part of the story of the drone’s life-history has been told. Though the son of a queen, he has never had a father; and should he ever attain to the dignity of fatherhood his posthumous children are all daughters, most of whom die spinsters within six or seven weeks of their birth, worn out by a life of ceaseless toil and drudgery!

The queen, it will be remembered, cohabits with the male but once in her life. The sperm-cells then received are stored in a special receptacle and are released during the passage of the egg down the oviduct. In this act of releasing the fertilizing germs a singular economy is practised. In the case of most other creatures myriads of sperm-cells are released for the fertilization of a single egg, and of these but one can possibly attain its goal, the minute aperture or “micropyle” which is the doorway to the germ liberated, in the form of an egg, by the female. The rest die. In the case of the queen bee but one of these precious sperm-cells is liberated at a time. Hence her prolonged ability to produce fertilized eggs. But eggs destined to produce males, or drones, are never thus fertilized: they are born without the intervention of a father. A queen which has never mated will lay only male-producing eggs. This is an astounding thing, but it is true. No less remarkable is the fact that the sperm-cells should survive in their encapsuled state for periods extending over several years: it seems almost incredible, but it is nevertheless true.

One cannot suppose that the queen in coming to a drone cell deliberately withholds the male germ as the egg passes down her oviduct; some inhibitory factor preventing the release of the sperm-cell must be brought into play which as yet we have not discovered. This production of males from unfertilized eggs, or “parthenogenesis” as it is called, is a common feature among the hymenoptera, and some other groups of insects, and it occurs also among other lowly creatures to be described later.

Having regard to the importance of the workers, a brief summary of their life-history must be given. These, it has already been indicated, are all, at any rate till three days old, potential queens. Their development into, or degradation to, the lower grade is determined, apparently, solely by the quality of the food, for the fact that queens are reared only in specially constructed cells of large size with walls of pollen instead of wax is explained by the larger size of the queen and the need for a more porous, air-permeated cell-wall on account of the longer time which must be spent in confinement. The worker is certainly the most “intellectual” member of the hive, but this superiority has been gained at a great price. Emerging from the chrysalis skin at about three weeks from the time that the egg from which she emerged was laid, she begins forthwith to gnaw her way through the mass of wax and pollen which forms the door of her prison. Rather, she eats her way through, for the material removed is swallowed as it is detached, thus the young bee, as Mr. Tickner Edwardes remarks, is caused to effect her own release by the promptings of her appetite. Hunger-strikes in the bee community are unknown. Speedily the youngster steps out, distinguishable from her elder sisters only by her weak, grey-hued, flaccid appearance. Her first act on gaining freedom is to groom herself down, after which she proceeds to explore the gloomy, busy, crowded thoroughfares of the hive. A day or two is thus passed in gathering strength. On the second appetite returns, and she proceeds to help herself from the vats of honey and pollen bins scattered here and there among the cradles of her sisters yet prisoners. But speedily she is caught and thrust, so to speak, on to the treadmill of work which is to know no cessation during her short span of life-some six or seven weeks. Her first duties are those of nursemaid. Without instruction, or previous experience, she begins to feed her younger sisters and brothers yet in the larval stage. But besides, during her first fortnight, before she is allowed to leave the hive she and her sisters of the same age have to fulfil a variety of tasks. All the indoor work of the house falls on these Cinderellas. Not only do they, and they alone, feed the young, but they have to produce the wax and build the combs and attend to the sanitary arrangements: “they are the brewers of the honey and the keepers of the stores; they feed the queen bee on her ceaseless rounds and give the drones, their brothers, their daily rations of bee-milk”—what else these lazy creatures need they take for themselves from the honey-vats. But this is not all. They have to meet their older sisters returning from the fields and gardens laden with nectar. This is regurgitated and transferred to the pouches of the youngsters, by whom it is transformed into honey and stored in the combs in the upper region of the hive. At the end of about a fortnight these little drudges are allowed a brief respite, during the heat of the day, to emerge into the outer air and gather ideas on the world which is yet to be explored. Soon a measure of freedom is allowed, the indoor work ceases, and each takes up the new and more agreeable task of gathering pollen, and after a few days of this the more responsible task of gathering nectar is undertaken, which is continued till death ends one of the most crowded, surely, of existences. Such as are born near “swarming-time” may have the good fortune to take part in the exodus and the settling down in the new home, and some may taste yet other moments of excitement, but they are moments only. The worker bee knows no leisure for the improvement of her mind and morals. She needs none, for she has neither: she is a creature of routine, a living automaton apparently. Yet there are incidents in this wonderful community which seem too complex to be merely the result of instinct unaided, uninspired, by intelligence albeit of a nebulous kind.

The worker-bees, it has been remarked, are barren: their reproductive organs are atrophied, and by the decree, not of the queen-mother of the hive, nor of the males, but of their own caste. In spite of the fact that they are incapable of producing offspring, they, and they alone, determine who shall undertake this task; and they decree the fate that awaits those thus appointed when they can no longer fulfil this purpose.

When the queen, waxing old, and waning in fecundity, lays fewer and fewer eggs, and these only producing males, they take silent note of the fact, and at the appointed time decree the death of their Sovereign-mother. Yet they hesitate to lay violent hands on her. She, as queen, claimed the right in her early youth to slay her sister-queens, and sped them with a dagger-thrust; now her turn comes to die. But it must be a bloodless death, carried out with due ceremonial. So her daughters cluster about her, and in a mock embrace, that tightens every moment, her breath is squeezed out of her body. There are no State pensions for those who are past work, but a State execution instead. This is vastly more economical, and it may yet commend itself to some would-be social “reformers,” who will doubtless contrive to make exceptions to the rule!

The execution of a queen is not an event of common occurrence; but that of male members of the hive forms part of the ordinary routine, though coming only within the larger cycle of the year. As the summer wanes and the harvest of nectar grows perceptibly less, visions of a possible famine, and its attendant horrors, seem to arise. So heads are counted and occupations are scrutinized, when it is discovered that the only members of the community who are contributing nothing to the general well-being are the males, who are now but useless drains on the hive. None of the neighbouring hives are now likely to send forth a virgin queen to her nuptials, to which end each hive is obliged to contribute—for no hive utilizes the services of its own drones; these idle fellows, then, are “eating their heads off”—and males, too; perish the thought! While they had anything to gain from him their motto was “Feed the brute”; but now, on each, doom is pronounced. It must be admitted that a live drone at the end of summer is one of life’s failures. Notoriously unable to feed himself save upon the honey made by his sisters, and having no function in life to perform save that of mating, his very existence now is a damning witness against himself.

When the mother of the hive ceases to maintain the standard of fertility set by her exacting daughters, she is put to death stealthily, as if in an excess of devotion: she is smothered under their embraces. Towards the drones now under sentence no such consideration is to be shown. When the word goes forth, the slaughter begins, and it gathers in ferocity. It begins in a massacre of the innocents—every helpless larval drone is ruthlessly dragged from its cot and thrown out of the hive to die: there is now no crime in infanticide, nor in the most gruesome massacre that is presently to follow. The drones, all unsuspecting, are to be tolerated a brief spell longer. The cool, calculating spirit of these unsexed ones seems to realize that there is even yet a remote possibility that the services of these doomed ones may be wanted. No sooner, however, does it become clear that this chance is past, than the decree of death is made absolute, and the poor drones are suddenly and viciously attacked by half a dozen frenzied spinsters at once. Each tries to bite through the base of the victim’s wings, and succeeding in this, he is speedily pushed towards the door of the hive and out into the open, whence return is impossible, so that nothing is left but death by starvation. Some of the victims will escape in the mêlée, but only for a brief season. Such as find their way, unmaimed, to the open air, are still faced by inevitable death. To remain out is to die of starvation or cold, to return is to fall a prey to the now infuriated guards, who, strongly reinforced, stand at the doorway of the hive to intercept and dispatch these unlucky fugitives. It will be remarked that these executioners make no use of their stings; these they might be unable to withdraw from their victim’s body, in which case they, too, would die. But there is no need to run this risk, for the males, their brothers, whom they so cheerfully slay, are unarmed; they may be attacked without risk. The dreadful work, however, is soon over, and the survivors, the queen and her daughters, have the house to themselves to make the final preparations for the winter sleep, which is apparently undisturbed by qualms of conscience.

There are certain structural differences distinguishing the three types in such a hive—the queen, the drone and the worker—which must now be referred to. The queen is larger than the worker; she has a larger and longer abdomen, a longer and much-curved sting, and her eyes have fewer facets. Only vestiges remain of the wax-secreting organs, and no trace is to be found of the wonderful pollen-baskets which perform so important a function in the worker; and finally, her instincts are of a very different kind.

The “pollen-basket” of the worker is a strange contrivance. The pollen is mainly collected by the hairs which clothe the under surface of the body, from which it is scraped by special brushes of hairs which clothe the inner surface of the “metatarsus “—the big, flat joint to which are attached a series of small triangular joints, the last of which bears the claws. When the brushes are “clogged up,” the legs are crossed and the pollen is combed out by specially stiff hairs on the “tibia”—the joint immediately above the metatarsus—and the bolus thus formed is then transferred to the outer surface of the tibia, which is trough-shaped, forming the “corbiculum,” or pollen-basket. The next, or middle, pair of legs are then employed to ram the pollen well into the basket, for safe conveyance to the hive. On arrival at the combs, the bee pushes its hind-legs into a cell, or “pollen-tub,” and with a special spur dislodges the pellet of pollen and lets it fall into the tub. These are complex movements, performed without instruction and, we must suppose, without any intelligent conception of their purpose.

The drone is larger than either queen or worker, and has enormous eyes, which meet one another over the top of the head; he has no wax-secreting organs, no pollen-basket, no sting. His antennæ are longer, his hum is deeper, his sole function is to fertilize a queen, and this done, he promptly dies. Failing in his first flight, he may make yet other ventures, but the chances are that he will die without attaining the only purpose for which he exists.

The fact that he lives for some days in the hive with the queen, before her nuptial flight, apparently unaware of her presence, would seem to indicate some special “trigger” for the release of the sexual instincts. But it must be remembered that he does not attain to maturity until after his first flight, and this it is, probably, which arouses the mate-hunger. More than this, however, it is probable that coitus is possible only when on the wing, when the air-sacs become inflated, and exert pressure on the genital organs. How he recognizes the queen when on her wild flight heavenwards is unknown: possibly by scent, but more probably by the very different vibrative note of her wings, that of the male being much stronger and deeper. His continued return to the hive is a proof of his failure to justify his existence, for no drone ever experienced Love’s embrace and lived to tell the tale: hence, when the time comes, he is slain without compunction.

These differences between the fully-developed male and female present nothing very striking; but how are the singular peculiarities of structure and instinct in the “workers” to be accounted for? They are present in neither queen nor drone, yet by them they are transmitted to their offspring from one generation to another! It is true that every worker, for a time, is a potential queen, and every queen, but for the grace of Chance, might have been a worker. All depends on the food. It is remarkable, but apparently the fact, that a more generous diet, or, rather, a more stimulating diet, should so profoundly modify the organism, but, it is to be noted, this sleight-of-hand is only successfully practised on a larva during its first three days of existence. Thus the royal bee jelly stimulates the growth of the sexual organs and inhibits the development of the structures peculiar to the worker—the basket, and pollen-hairs, and so on. These structures are not made by the food; they are simply nourished or inhibited, as the case may be. Nevertheless, one cannot help being mystified by the fact that the mere difference in the quality of the food, or, rather, in the chemical constituents thereof, should cause the inhibition, or, rather, the suppression, of relatively complex structures like the corbiculum and the reduction of the number of the facets of the eye. To say that the structures inhibited, in the case of the queen, are just those which will be of no service when in her royal state, is by no means to explain the mystery. And what is true of the physical side is no less true of the psychical, for with this change of diet the behaviour of the insect, throughout its whole life, is most profoundly changed. If the pollen-basket is wanting, no less so are the instinctive actions associated with its use; if the genital organs are atrophied, so also are the instinctive acts associated therewith. This nexus between instinct and structure is not to be lost sight of.

How—and the question has often been asked—are the experiences of the infertile females, the workers, transmitted to the germ-plasm? For the workers, it has been contended, being sterile, are incapable of handing on such acquirements: this is so. These workers hold the same position in regard to the species that structures essential to well-being hold in regard to the individual. These last are not under the control of the individual, but are determined by a plus or minus quality in its germ-plasm. The worker-bees are products of the germ-plasm, committed to the care of the queens. Any strain, so to speak, of that germ-plasm which gives rise to defective workers brings about its own extinction, or elimination, sooner or later. Any strain of germ-plasm which contains, so to speak, a spark of that quality which in the individual is expressed by intelligent behaviour, will gain advantages in the struggle for existence.

The complex, the extraordinarily complex, behaviour of the worker-bees on any interpretation is still mysterious. This interpretation can be tested only by a reference to the life-history of other social-bees which have attained to a less complexity. This shows us that the sterile worker is not to be regarded as a newly-evolved type so much as an arrested stage of a more complete ancestral condition, and the fact that the worker is potentially a queen is further evidence of this.

A clue to many of the more puzzling features presented by the domestic economy of the Hive-bee may be obtained by a study of the life-history of other species of social-bees which have not attained to so high a degree of specialization. The Bumble-bees afford illustrations of the stages through which Apis mellifica, the Hive-bee, must have passed.

In the stone Bumble-bee (Bombus lapidarius), a queen, who has passed the winter in blissful sleep, will lay the foundation for a new colony on some bright May morning by collecting a small quantity of moss. This done, she starts forth to gather pollen, with which, under cover of the moss, she forms a waxen cell, mixing the newly-gathered pollen with the wax so mysteriously formed within her body, as in the case of Hive-bees of the worker type. Slowly and laboriously this waxen cradle grows. Fashioned like a globe, its inner surface is lined with pollen soaked in honey, and with the last pellet of this a number of eggs are laid arid the nursery is sealed up. By the time these labours are completed the queen is worn out; she therefore rests awhile, clinging to the outer wall of this cunningly-wrought cradle. After a few days’ rest she adds another and commonly yet a third cell to the first, joining each to the other with wax. But before the third cradle is finished the eggs in the first have hatched. The youngsters will have consumed the layer of honey-soaked pollen placed there for this purpose. They therefore require feeding, and thus the labours of this very industrious queen are still further increased. Divining the needs of her imprisoned first-born, she bites a small hole through the nursery wall and pours in a quantity of honey for their sustenance. In due time they are “full-fed,” and each spins for itself a silken vestment wherein to undergo its transformation into a worker-bee. The careful mother, during this period of transition, now scrapes away an opening through which the young bees may creep when they awake. This event takes place in the course of a few days, when her work is materially lightened, for these newly-hatched workers at once take over the duties of building nurseries and feeding the further batches of young which, for a time, follow one another in quick succession. The queen, indeed, has now nothing else to do but to lay eggs in the nurseries as they are ready. So far all the children born to her are daughters. The earliest-born, it is to be noted, were “workers”; those which follow and are tended by the workers are also females, and supplement their mother’s labours by producing fertile eggs, though they have never even seen the male of their own species. Thus, if the queen-mother die her virgin daughters carry on the colony. But it sometimes happens that she may have left no descendants capable, for the time, of laying fertile eggs. In this case, if there be larvæ still in the nursery, the workers feed them assiduously as if in the hope that some may prove fertile. But if there be no infants to be fed they apparently abandon work, become despondent, and spend the greater part of their time sitting at home by the empty cradles, till at last death comes to their rescue and the colony is extinct.

Much that baffles one in the history of the Hive-bee becomes clear in the light of the facts revealed by the life-story of the Bumble-bee. In the first place it will be remembered her first eggs produced only workers, which appeared at a time when her energies were severely strained, and their food allowance was no more than barely sufficient to sustain life. The females which appeared later produced fertile eggs, having been more abundantly fed by their infertile elder sisters. The number of fertile females which appear at this stage of the colony seems again to be regulated by the abundance of food, which varies in amount with fine, or cold, weather. Even among the worker broods fertile females may appear. They owe their fertility apparently to good luck, which afforded them the opportunity of securing more food than their sisters. The birth of young from females about whose virginity there can be no question is certainly remarkable, but it would seem that this parthenogenetic state is one of limited endurance, for towards the end of summer males appear, and these mating with some of the later-born females, lead again to the appearance of a queen, who, being fertilized, alone survives the winter to carry on the race with the succeeding summer.

Thus, then, the mysterious existence of the workers among the Hive-bees, displaying structural peculiarities and instincts so different from those of the queen-mother, is explained. For the queen, in this case, is evidently the product of a more intensified, more perfected, social system, relieved, from the first, of the labours of building and the care of her offspring, duties which the queen Bumble-bee has at first to perform for herself, because all her children die at the end of the summer. Among Hive-bees fertile workers also occasionally occur; they are probably bees which in their larval state received a more than usually abundant supply of food, or food approximating to the “bee jelly” which produces young queens. The difference, then, between the individuals of a colony of Hive-bees and one of Bumble-bees lies in the greater abundance of fertile workers and in the fact that the queen of the Hive-bees is relieved of all work from the first, and so is enabled to devote her whole energies to the duties of reproduction. She is the descendant of a race of queens which in earlier times, like the Bumble-bee queen, had to perform the duties now relegated to her daughters, who inherit not only her house-building and child-nurturing instincts, but also her potentiality for child-bearing, though this potentiality is commonly inhibited by the starvation of the reproductive activities. Selection secures survival of this state of affairs by the elimination of any tendency to lose any of these qualities on the part of the queen. The workers of the Hive-bee, in short, have not evolved their peculiarities of structure and instinct by some mysterious process of natural selection confined to the workers individually, for these, being infertile, could not transmit any of their inherent qualities or tendencies to variation in the direction of more efficient workers. On the contrary, all that they possess they inherit from the queen-mother, who transmits to her offspring the qualities and characteristics her forebears in the female line possessed in their own person.

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.

The phenomenon of virgin birth is one of profound mystery. The existence of so astonishing a mode of reproduction was an established belief among the ancients, though they could have had no means of demonstrating the faith that was in them. But these men saw no difficulty in ascribing to the females of their own race this faculty of producing offspring without the intervention of a male. One suspects, indeed, that there was no solid foundation whatever for this belief in these miraculous powers: they lived in credulous times, and the recorded occurrences of these, even to them, irregular births are to be regarded as devised to afford a convenient means of escape from the consequences of lapses from the path of virtue. Yet, incredible as it may appear, there are not wanting to-day both men and women who affect to believe that this mode of reproduction obtains still among the human race, in certain exceptional cases; and further, they profess a conviction that in the future it may become the normal mode, males, in consequence, becoming unnecessary! Such professions of faith are made only by the ignorant, or by those who trade on human credulity. Parthenogenesis not only does not occur in the human race, but it does not even occur in any member of the great group of vertebrates of which man himself stands at the head, and it never will occur.

Those near relations of the Bees, the Ants, afford a further insight into this strange method of reproduction. Each community in the case of these insects harbours not one, but many queens. The nuptial flight, like that of the Bees, takes place in mid-air; but myriads of both sexes participate therein, forming a filmy, ever-shifting cloud, now rising, now falling, in the shimmering sunlight. At no time do they seek to attain the altitude, or the privacy, so strenuously striven for by the Bees. But in the case of the latter there is but one female, and her life is precious. She must seek sanctuary for the consummation of her marriage in the highest heavens, beyond the risk of instant destruction by insect-eating birds; for though thousands of suitors accompany her, she rises above them all, save one or two, and hence would form an easy mark. With the Ants there are thousands of queens, and the destruction of a few hundreds more or less is rather an advantage to the species than otherwise. On their return to earth the males die: their life’s work is accomplished. The females, or as we must call them, the queens, on the other hand, have a long life before them; far longer than that of the queen bee. But for them the joys of flight are restricted to this one brief revel, for, no sooner have they reached terra firma, than they renounce, as it were, the pleasures of life to devote themselves entirely to the work of reproduction. And as if to make all regrets vain, to stamp out all possible temptation to desert their vows, they tear off their gauzy wings, and with them goes all hope of fertile repentance: for the rest of this life their home is underground.

Each queen, on her descent, departs a separate way, and hard is the road before her. She left the parental nest well-fed, and in good liking, her body well, stored with food in the shape of fat and the now useless, bulky, wing-muscles, and with this, her only dowry, she starts the formation of a new colony out of her own substance. Her first task is to form a burrow, and at the end of this she fashions a small chamber. This done, she closes the mouth of the burrow and cuts herself off from the world. The labour of this burrowing is so severe that it often wears away her teeth, her only tools, and the hairs from her body. In this retreat she now waits patiently for the eggs within her to ripen, which may take months to accomplish: she is still fasting, or, rather, feeding upon herself. When at last the eggs are laid and hatched, she feeds her children on saliva, the very juice of her body, for she is still fasting. Nor is the strain relaxed till the larvæ undergo their transformation into pupæ, and, after a brief sleep, emerge as “worker” Ants, puny in stature owing to the poorness of their food during larval life. In some species this fast may last for ten long months. So soon, however, as these little workers emerge, like dutiful daughters they make their way to the outer world, and go forth in search of food, which they share with their now exhausted mother. But, besides, they enlarge the original chamber, and drive galleries in all directions to provide accommodation for the vast population that is soon to crowd the thoroughfares. Meanwhile the queen resumes her task of producing more and yet more daughters, in whom she now displays not the slightest interest. Her elder children now bear away the eggs, and feed the young as they hatch. In course of time, as with the Bees, the task of wet-nurse falls on the youngest of the Ants, those who have just attained to anthood. For ten or fifteen years this queen-mother may continue her work of reproduction, a slave, indeed, to domesticity, with monotonous regularity, checked only by the chill of autumn and the sleep of winter.

Those among our own race who profess to hail the prospect of a time when parthenogenesis shall be the normal mode of reproduction may well take the Ant as an awful warning. Their ambitions may overreach the mark. The poor queen becomes a slave to reproduction; children in myriads are born to her; even if she would she could not sustain her interest in them, she could not even recognize them as the fruit of her body. Her daughters are born to a lifelong drudgery, her sons are mere fertilizing agents: for their only purpose in life is to perpetuate this awful thraldom, this appalling prolificness; and having accomplished this, they die forthwith. If there be any joy in this life it is drunk by the males alone. Thus does the female rule overreach itself. It is well, indeed, that the participants of the joyous nuptial flights dancing deliriously on gauzy wings in the glare of a summer day, have no foreknowledge of the long night that is to follow.

Unlike the Bees, the Ants may produce as many as five grades of workers, each of which have different duties towards the community. But the nature of those duties and the manner of the evolution of these types, are themes foreign to these pages: enough has been said already to indicate the nature of the problems they present when discussing the life-history of the Bees.

The subject of parthenogenesis need be pursued no further in this volume than is sufficient to bring out its retrograde character. It is a form of reproduction which may be limited to a small number of generations, as with the Aphides, or to a single generation alternating with normal sexual generations, as in many Cynipidæ or Gall-flies, or it may be the only mode of reproduction, as in some other Gall-flies, some Saw-flies and some Crustacea, wherein no males have ever been seen. In some species this form of reproduction gives rise to females only—the Thelyotokous parthenogenesis of scientific text-books—as in the Saw-flies and Gall-flies, and the parasitic Tomognatbous. In some other Saw-flies, unfertilized queens and workers of Ants, Bees, and Wasps, which occasionally produce offspring, the progeny is always male, and this is known as Arrhenotokous parthenogenesis. In one or two species of Saw-fly, e.g. Nematus curtispina, both males and females may be produced, when the species is said to be Deuterotokous.

In the case of the Aphides, winged males normally appear in large numbers at the end of the summer, and these fertilize the females; but if kept in a warm green-house, parthenogenetic reproduction may be sustained for as long as four years. Under quite normal circumstances these tiny insects show a singular range of variability, for egg-laying and viviparous individuals are met with; while winged and wingless generations appear sporadically, apparently according to the abundance of food. The winged form is sometimes so abundant as to float about in swarms that darken the air. There are at least three kinds of males-winged males, wingless males with a functional mouth, and small wingless males which have no mouth, and, one need hardly say, are very short-lived. The Aphides are a feeble folk, individually, but collectively a power in the land, causing at times incalculable loss to the farmer and gardener; but on this head and on the subject of their strange habits, and sometimes adventurous lives as slaves in the service of Ants, no more than a hint may be dropped in these pages. But some such aids to faith seem to be necessary when those who are not tolerably familiar with these insects are told of their amazing fertility. Linnæus long since estimated, in regard to one species, that in the course of one year a single Aphis will give rise to a quintillion of descendants—all produced without the aid of a male. Every one of these females begins to reproduce within from ten to twenty days of her birth, but even this statement does not bring home the result of such an astounding fecundity like Huxley’s calculation which was carefully worked out. He estimated that the produce of a single female would, in the course of ten generations, supposing all the individuals to survive—and possess the normal fertility of their race—“contain more ponderable substance than five hundred millions of stout men: that is, more than the whole population of China.”

To explain such a riot of reproduction one might almost suppose these insects to be imbued with a dread of the impending dissolution of their race, and endowed with the power to avert such a calamity by these stupendous efforts; for it is evident that parthenogenesis confers quite extraordinary powers of raising the birth-rate. But then the normal mode of procreation is capable of achieving results quite as remarkable. The queen Termite or White Ant, for instance—which, by the way, is no Ant, but a near relation of the Stone-flies—when in her prime will lay eggs at the rate of sixty a minute, or eighty thousand and upwards in the course of a day of twenty-four hours. But this unenviable mode of breaking the record is attended, surely, with some little inconvenience; for to attain to such fertility her abdomen increases until it attains something like two thousand times that of the workers of the community in which she lives. That the history of the queen Termite is unique of its kind is not surprising: indeed, such an amazing story could only be told of creatures which enjoyed the seclusion of a subterranean existence. Here, on a bare couch, with her Royal spouse beside her, she lies, a bloated, heaving mass, incapable of movement, depositing eggs with the rhythm of a machine, the mother of offspring which she will never see. A more unsightly picture of maternity it would be impossible to conceive: it is well, indeed, that it is hidden from the light of day. No such state of affairs could ever arise among creatures living an outdoor life, with enemies to avoid, and food to find.

The instances just surveyed, these extremes of the potentiality of procreation, are instructive in more ways than one. They are to be regarded as “excrescences” of reproduction, comparable to those “excrescences” of individual growth which we call “ornament,” for example. Individuals on whom this fertility has settled, so to speak, are the victims of the machinery of sex and reproduction. Their amazing powers of multiplication are not of their own seeking, they are inherent manifestations of variations of growth, uncontrollable save by the machinery of Natural Selection. Incidentally such victims serve a useful purpose, for their myriad hosts afford food for hordes of other animals, which in turn are eaten. Little though we realize it, the well-being of the human race would suffer if these prolific creatures—the uncomplaining victims of that inexorable law which bids all living things “increase and multiply” or die—should cease to be; for with them would disappear a host of animals on whose existence man’s comfort more or less depends.

During the millions of years that have rolled by since the first appearance of life on the earth, who shall count the number of types which have been exterminated without leaving the faintest trace of their having ever existed? The survivors which have contrived to maintain a place in the sun present an infinite range of variation in colour, size, habit, and structure, as well as in emotions. These varied aspects are all so many facets of the mysterious phenomenon we call Life: and they are so many witnesses of the versatility of Life. Not the least mysterious feature of this Life is its faculty of reproduction, which expresses itself in an infinite variety of ways, defying all but the crudest forms of analysis. The evolution of sex has exercised the speculative ingenuity of some of the acutest students of Nature from the earliest times, and we are still far from a satisfactory solution of the problems it presents. Hermaphroditism and Parthenogenesis are commonly regarded as degenerate forms of reproduction, but it would probably be more correct to see in them exceptional modes of adaptation enabling such individuals to occupy niches in the world untenable to creatures of more conservative habit. That the peculiar “strains” of animal life have turned into backwaters which offer no opportunity or possibility of further advancement seems clear enough, but they are nevertheless interesting and instructive.

The parthenogenetic Crustacea and the Rotifers afford some good evidence of this adaptability—of the way in which creatures manage to cling to the skirts of life by reason of their power to survive the extremest tests of endurance. And this success has largely been due to some mysterious property of the germ-plasm enabling reproduction to take place through the female line alone, or in some cases with an occasional fillip from the intervention of males. Of the many marvellous things that could be related of these creatures but few instances can be cited here.

The case of the Brine Shrimp (Artemia salina) will afford an exceptionally good illustration because the facts can be tested by anyone who will take the trouble to make a simple experiment for himself. Those anxious to do this should dissolve eight ounces of Tidman’s sea-salt in a glass jar containing five pints of water, keeping the mixture well stirred till the salt is dissolved. It should be allowed to stand and be carefully watched. In about three days, with a pocket-lens, or even without, minute white specks will be seen moving with a jerky motion up and down the water. These are larval Brine Shrimps. Now they must be fed. Take a piece of lettuce-leaf or any green stuff, and pound it up, or grind it up with a knife-blade on a plate with a little water, till the whole is reduced to the consistency of green paint; then empty this into the water. This must be done daily, or at any rate frequently. Quickly these tiny specks will grow into Brine Shrimps, translucent creatures nearly half an inch long, swimming about back downwards with a marvellously rhythmical movement of delicate feet. In all probability no males will be found, but, on the other hand, both sexes in almost equal numbers may be present. The males may readily be distinguished by their massive arms immediately behind the head, for the purpose of embracing the females.

Whence came these wonderful animals? The mystery is easily explained. The salt is genuine sea-salt, formed in brine-pans, chiefly in the Mediterranean. As the water evaporated the Shrimps it contained gradually died; but the eggs in the females became encapsuled in the salt-crystals to hatch out long months after. In one of my own experiments I succeeded with salt that I had kept for more than a year. Of course, every sample of salt experimented with will not yield successful results, but failures are not expensive. Now in this brine-pan there were myriads of other animals which were killed outright: the Brine Shrimp is at least able to pass on descendants by reason of the vitality of its eggs. Some near relations of the Brine Shrimps live in fresh water and possess similar powers of resistance to adverse conditions. The Fairy Shrimp (Chirocephalus) is one of these. Not unlike its cousin the Brine Shrimp in appearance, it lives in shallow pools, such as have muddy bottoms and are constantly liable to dry up. Birds hunting by the margins of the pool where the retreating water has left a fringe of mud bear away more or less of this on their feet and transport it to similar pools, or even puddles. Such transplanted samples may easily contain numbers of eggs of this tiny creature. Only a year or two ago Fairy Shrimps were found in abundance in rain pools at Eton, and some, indeed, were discovered swimming gaily about in a rain-filled cart-rut!

Another very singular Crustacean, known as Apus, bears a curious superficial likeness to the King Crab (Limulus), having a large back-shield and a long tail. This little creature, a giant compared with his nearest relations, is an inhabitant of wayside ponds and ditches. Thousands of females may be taken for years in succession without the advent of a single male. Then, for some strange reason which we cannot even guess at, males appear. Like its freshwater cousin, the Fairy Shrimp, Apus can withstand drought: its favourite haunts may be transformed into sun-baked hollows, but with a heavy fall of rain and a few hours’ soaking the eggs left by dead females develop, and once more the pool and its inhabitants are established again. Having regard to the extraordinary vitality of these small creatures, it is curious that they should ever disappear from their favoured haunts. But they do. Not many years ago Apus could be found in abundance in many parts of the South of England. It is now extinct; its last resorts were the ponds at Hampstead: now one may search in vain for them. “No British specimens,” remarks Dr. Caiman, a great authority on the Crustacea, “had been recorded for over forty years, and the species was believed to be extinct in this country, when it was found in 1907 by Mr. F. Balfour Browne in a brackish marsh near Southwick, in Kirkcudbrightshire.” These had probably developed from eggs accidentally transported by some bird from the Continent. The extinction of the race throughout the British Islands can only be attributed to the too long absence of males, and the consequent inability to restore vigour by the more normal method of reproduction by sexual congress.

Among the Rotifers the little Wheel-animalcules exhibit an even greater vitality, for not only can their eggs withstand prolonged desiccation, but in some the body of the animal survives even harsher treatment. If specimens be enclosed within a chamber containing a little sand or moss the contents may be dried over sulphuric acid, or heated up to 200° F., or left to the neglected dust of years, and will yet revive if a little fresh water be added to the sand. Males are rare, and when they do occur are little more than animated receptacles for semen, for they are incapable of feeding, the gullet and digestive tract being reduced to a solid cord. A certain amount of nourishment, however, may be absorbed through the delicate body wall.

The degeneration of the males in these parthenogenetic species irresistibly reminds one of the smile of the Cheshire cat; they grow smaller and smaller, and their functions less and less, till finally nothing is left. The “complemental males” discovered years ago by Darwin in the Barnacles well illustrate this process. In dissecting adult specimens of the stalked Barnacle (Scalpellum) he found, just inside the valves, in a pocket of the mantle, a varying number of “complemental males,” tiny organisms which Mr. Geoffrey Smith describes as “little more than bags of spermatozoa,” and they apparently serve to fertilize the ripe ova of the larger animal—one cannot say of the female, for Scalpellum, like most of the Barnacles, is hermaphrodite. But it is believed that these complemental males are really arrested hermaphrodites. At any rate, if it so be noted that with some of the Barnacles, as with some other Crustacea, the larvæ are males, but when adult life is attained female glands appear and hermaphroditism is established. Such hermaphrodites have the singular distinction of being males which have acquired female attributes, true females being unknown among them!

In one of the parasitic Crustacea (Chondracanthus) infesting the gills of Gurnard, Plaice, Skate and other fish, the adult female is about half an inch long, and very unlike a Crustacean in appearance; the male is an extremely minute maggot-like object—a few millimetres in length—and lives permanently attached to the belly of his mate just at the base of the egg masses. More remarkable still is the case of another nearly related parasitic species—Lernea—which becomes sexually mature in its childhood. The males perform their part and die; their mates arrive at maturity and settle down to a comfortable life as parasites on fish, reproducing without further mating.

That Parthenogenesis and Hermaphroditism are but specialized forms of reproduction, leading sooner or later to degeneration and extinction, there can be no doubt. They are, so to speak, failures in the evolution of sex, demonstrating in a very forcible fashion the impossibility of progress—as we understand it—where the sexual functions are thus combined.

To the differentiation of sex, resulting in separate male and female individuals, we must attribute the marvellous complexity of the pageant of life which confronts us to-day. The story of the Courtship of Animals is only one of an infinite number of incidents in this pageant, and one which is by no means easy of interpretation.

In these pages an attempt has been made to show that this differentiation of sex has, throughout, been accompanied by, and largely moulded by, common instincts and behaviour, and this interpretation is only to be reached by a study of the phenomena in their simplest form among the lower grades of animal life. Colour and the various sexual differences in form have been allowed to dominate this investigation of the problem of sex, and have diverted attention from more profitable and fruitful channels.

The lower we descend in the scale of animal life the less convincing becomes the argument that the colour, ornament or armature of the males is the result of sexual selection in the older, Darwinian sense. The argument of Geddes and Thomson and others that the males are more “katabolic,” the females more “anabolic,” seems no less unsatisfactory, for in many cases the female is just as highly ornamented as the male, and in others she is considerably large. Further, in their less specialized species the sexes are almost or quite indistinguishable externally, and are sombrely clad, just as at the opposite extreme we find them equally ornamented and equally active.

We shall be nearer the truth if we regard these secondary sexual characters as expression points of germinal variations. Though we seem hopelessly ignorant as to the inciting cause of the variations, at least we seem to be able to lay a finger on the agents by which they are effected. And these are the hormones of the primary and secondary sexual glands, whose functions affect more than the merely sexual side of the organism. They profoundly affect the coloration of animals, giving rise on the one hand to purely ornamental “secondary sexual characters,” and on the other to changes of coloration which achieve the ends of protective resemblance colours, or of “warning coloration,” as circumstances may demand. There is nothing more remarkable in this than the control which the pituitary body exercises over stature, either when in a pathological condition, or when the controlling action of the other gland secretions is removed, as by castration.

Hitherto much has been made of trophic nerves, which control growth; but it is probable we have overlooked the still more important action of “trophic” glands, such as the thyroid. This apparently controls growth in many directions. Adaptations to environment which are effected by changes in bodily shape-as in the transformation of land-dwelling mammals into Seals and Whales—are probably largely controlled by these glands. Their activity is as great as their manifestation is varied.

Why their action should be more stimulating in the case of the male, why he should lead the way in all the new acquirements of the species, both in non-sexual as well as in sexual characters, is by no means plain. But the fact remains that this is so. Remove any one of these glands and the machinery of growth is thrown out of gear; it is not merely the secondary sexual characters which are affected.

But these glands are concerned no less intimately with the behaviour of animals. This is most obvious in all that concerns sexual appetite as the preceding chapters have already shown. Having regard to the immense variety of animals concerned, this behaviour presents an underlying uniformity of expression which must not be lost sight of: and the same is no less true of what we may call the physical manifestations of these glandular activities.