Social Life in the Insect World Part 12

The invariable situation of the wound being proved, I bend back the head of the bee, so as to open the articulation. I see under what we may call the chin of the bee a white spot, hardly a twenty-fifth of an inch square, where the h.o.r.n.y integuments are lacking, and the fine skin is exposed uncovered. It is there, always there, in that tiny defect in the bee's armour, that the sting is inserted. Why is this point attacked rather than another? Is it the only point that is vulnerable? Stretch open the articulation of the corselet to the rear of the first pair of legs. There you will see an area of defenceless skin, fully as delicate as that of the throat, but much more extensive. The h.o.r.n.y armour of the bee has no larger breach. If the Philanthus were guided solely by considerations of vulnerability she would certainly strike there, instead of insistently seeking the narrow breach in the throat. The sting would not grope or hesitate, it would find its mark at the first attempt. No; the poisoned thrust is not conditioned by mechanical considerations; the murderer disdains the wide breach in the corselet and prefers the lesser one beneath the chin, for purely logical reasons which we will now attempt to elicit.

The moment the bee is stung I release it from the aggressor. I am struck in the first place by the sudden inertia of the antennae and the various members of the mouth; organs which continue to move for so long a time in the victims of most predatory creatures. I see none of the indications with which my previous studies of paralysed victims have made me familiar: the antennae slowly waving, the mandibles opening and closing, the palpae trembling for days, for weeks, even for months. The thighs tremble for a minute or two at most; and the struggle is over.

Henceforth there is complete immobility. The significance of this sudden inertia is forced upon me: the Philanthus has stabbed the cervical ganglions. Hence the sudden immobility of all the organs of the head: hence the real, not the apparent death of the bee. The Philanthus does not paralyse merely, but kills.

This is one step gained. The murderer chooses the point below the chin as the point of attack, in order to reach the princ.i.p.al centres of innervation, the cephalic ganglions, and thus to abolish life at a single blow. The vital centres being poisoned, immediate death must follow. If the object of the Philanthus were merely to cause paralysis she would plunge her sting into the defective corselet, as does the Cerceris in attacking the weevil, whose armour is quite unlike the bee's. Her aim is to kill outright, as we shall presently see; she wants a corpse, not a paralytic. We must admit that her technique is admirable; our human murderers could do no better.

Her posture of attack, which is very different to that of the paralysers, is infallibly fatal to the victim. Whether she delivers the attack in the erect position or p.r.o.ne, she holds the bee before her, head to head and thorax to thorax. In this position it suffices to flex the abdomen in order to reach the joint of the neck, and to plunge the sting obliquely upwards into the head of the captive. If the bee were seized in the inverse position, or if the sting were to go slightly astray, the results would be totally different; the sting, penetrating the bee in a downward direction, would poison the first thoracic ganglion and provoke a partial paralysis only. What art, to destroy a miserable bee! In what fencing-school did the slayer learn that terrible upward thrust beneath the chin? And as she has learned it, how is it that her victim, so learned in matters of architecture, so conversant with the politics of Socialism, has so far learned nothing in her own defence? As vigorous as the aggressor, she also carries a rapier, which is even more formidable and more painful in its results--at all events, when my finger is the victim! For centuries and centuries Philanthus has stored her cellars with the corpses of bees, yet the innocent victim submits, and the annual decimation of her race has not taught her how to deliver herself from the scourge by a well-directed thrust. I am afraid I shall never succeed in understanding how it is that the a.s.sailant has acquired her genius for sudden murder while the a.s.sailed, better armed and no less powerful, uses her dagger at random, and so far without effect. If the one has learned something from the prolonged exercise of the attack, then the other should also have learned something from the prolonged exercise of defence, for attack and defence are of equal significance in the struggle for life. Among the theorists of our day, is there any so far-sighted as to be able to solve this enigma?

I will take this opportunity of presenting a second point which embarra.s.ses me; it is the carelessness--it is worse than that--the imbecility of the bee in the presence of the Philanthus. One would naturally suppose that the persecuted insect, gradually instructed by family misfortune, would exhibit anxiety at the approach of the ravisher, and would at least try to escape. But in my bell-gla.s.ses or wire-gauze cages I see nothing of the kind. Once the first excitement due to imprisonment has pa.s.sed the bee takes next to no notice of its terrible neighbour. I have seen it side by side with Philanthus on the same flower; a.s.sa.s.sin and future victim were drinking from the same goblet. I have seen it stupidly coming to inquire what the stranger might be, as the latter crouched watching on the floor. When the murderer springs it is usually upon some bee which pa.s.ses before her, and throws itself, so to speak, into her clutches; either thoughtlessly or out of curiosity. There is no frantic terror, no sign of anxiety, no tendency to escape. How is it that the experience of centuries, which is said to teach so much to the lower creatures, has not taught the bee even the beginning of apine wisdom: a deep-rooted horror of the Philanthus? Does the bee count upon its sting? But the unhappy creature is no fencer; it thrusts without method, at random. Nevertheless, let us watch it at the final and fatal moment.

When the ravisher brings her sting into play the bee also uses its sting, and with fury. I see the point thrusting now in this direction, now in that; but in empty air, or grazing and slipping over the convexity of the murderer's back, which is violently flexed. These blows have no serious results. In the position a.s.sumed by the two as they struggle the abdomen of the Philanthus is inside and that of the bee outside; thus the sting of the latter has under its point only the dorsal face of the enemy, which is convex and slippery, and almost invulnerable, so well is it armoured. There is no breach there by which the sting might possibly enter; and the operation takes place with the certainty of a skilful surgeon using the lancet, despite the indignant protests of the patient.

The fatal stroke once delivered, the murderer remains for some time on the body of the victim, clasping it face to face, for reasons that we must now consider. It may be that the position is perilous for Philanthus. The posture of attack and self-protection is abandoned, and the ventral area, more vulnerable than the back, is exposed to the sting of the bee. Now the dead bee retains for some minutes the reflex use of the sting, as I know to my cost: for removing the bee too soon from the aggressor, and handling it carelessly, I have received a most effectual sting. In her long embrace of the poisoned bee, how does Philanthus avoid this sting, which does not willingly give up its life without vengeance? Are there not sometimes unexpected accidents? Perhaps.

Here is a fact which encourages me in this belief. I had placed under the bell-gla.s.s at the same time four bees and as many Eristales, in order to judge of the entomological knowledge of Philanthus as exemplified in the distinction of species. Reciprocal quarrels broke out among the heterogeneous group. Suddenly, in the midst of the tumult, the killer is killed. Who has struck the blow? Certainly not the turbulent but pacific Eristales; it was one of the bees, which by chance had thrust truly in the mellay. When and how? I do not know. This accident is unique in my experience; but it throws a light upon the question. The bee is capable of withstanding its adversary; it can, with a thrust of its envenomed needle, kill the would-be killer. That it does not defend itself more skilfully when it falls into the hands of its enemy is due to ignorance of fencing, not to the weakness of the arm.

And here again arises, more insistently than before, the question I asked but now: how is it that the Philanthus has learned for purposes of attack what the bee has not learned for purposes of defence. To this difficulty I see only one reply: the one knows without having learned and the other does not know, being incapable of learning.

Let us now examine the motives which induce the Philanthus to kill its bee instead of paralysing it. The murder once committed, it does not release its victim for a moment, but holding it tightly clasped with its six legs pressed against its body, it commences to ravage the corpse. I see it with the utmost brutality rooting with its mandibles in the articulation of the neck, and often also in the more ample articulation of the corselet, behind the first pair of legs; perfectly aware of the fine membrane in that part, although it does not take advantage of the fact when employing its sting, although this vulnerable point is the more accessible of the two breaches in the bee's armour. I see it squeezing the bee's stomach, compressing it with its own abdomen, crus.h.i.+ng it as in a vice. The brutality of this manipulation is striking; it shows that there is no more need of care and skill. The bee is a corpse, and a little extra pus.h.i.+ng and squeezing will not deteriorate its quality as food, provided there is no effusion of blood; and however rough the treatment, I have never been able to discover the slightest wound.

These various manipulations, above all the compression of the throat, lead to the desired result: the honey in the stomach of the bee ascends to the mouth. I see the drops of honey welling out, lapped up by the glutton as soon as they appear. The bandit greedily takes in its mouth the extended and sugared tongue of the dead insect; then once more it presses the neck and the thorax, and once more applies the pressure of its abdomen to the honey-sac of the bee. The honey oozes forth and is instantly licked up. This odious meal at the expense of the corpse is taken in a truly sybaritic att.i.tude: the Philanthus lies upon its side with the bee between its legs. This atrocious meal lasts often half an hour and longer. Finally the exhausted corpse is abandoned; regretfully, it seems, for from time to time I have seen the ogre return to the feast and repeat its manipulation of the body. After taking a turn round the top of the bell-gla.s.s the robber of the dead returns to the victim, squeezes it once more, and licks its mouth until the last trace of honey has disappeared.

The frantic pa.s.sion of the Philanthus for the honey of the bee is betrayed in another fas.h.i.+on. When the first victim has been exhausted I have introduced a second bee, which has been promptly stabbed under the chin and squeezed as before in order to extract its honey. A third has suffered the same fate without appeasing the bandit. I have offered a fourth, a fifth; all are accepted. My notes record that a Philanthus sacrificed six bees in succession before my eyes, and emptied them all of honey in the approved manner. The killing came to an end not because the glutton was satiated, but because my functions as provider were becoming troublesome; the dry month of August leaves but few insects in the flowerless garden. Six bees emptied of their honey--what a gluttonous meal! Yet the famis.h.i.+ng creature would doubtless have welcomed a copious addition thereto had I had the means of furnis.h.i.+ng it!

We need not regret the failure of bees upon this occasion; for what I have already written is sufficient testimony of the singular habits of this murderer of bees. I am far from denying that the Philanthus has honest methods of earning its living; I see it among the flowers, no less a.s.siduous than the rest of the Hymenoptera, peacefully drinking from their cups of nectar. The male, indeed, being stingless, knows no other means of supporting himself. The mothers, without neglecting the flowers as a general thing, live by brigandage as well. It is said of the Labba, that pirate of the seas, that it pounces upon sea-birds as they rise from the waves with captured fish in their beaks. With a blow of the beak delivered in the hollow of the stomach, the aggressor forces the victim to drop its prey, and promptly catches it as it falls. The victim at least escapes with nothing worse than a blow at the base of the neck. The Philanthus, less scrupulous, falls upon the bee, stabs it to death and makes it disgorge in order to nourish herself upon its honey.

Nourish, I say, and I do not withdraw the expression. To support my statement I have better reasons than those already presented. In the cages in which various predatory Hymenoptera whose warlike habits I am studying are confined, waiting until I have procured the desired prey--not always an easy proceeding--I have planted a few heads of flowers and a couple of thistle-heads sprinkled with drops of honey, renewed at need. On these my captives feed. In the case of the Philanthus the honeyed flowers, although welcomed, are not indispensable. It is enough if from time to time I place in the cage a few living bees. Half a dozen a day is about the proper allowance. With no other diet than the honey extracted from their victims I keep my specimens of Philanthus for a fortnight and three weeks.

So much is plain: in a state of freedom, when occasion offers, the Philanthus must kill on her own account as she does in captivity. The Odynerus asks nothing of the Chrysomela but a simple condiment, the aromatic juice of the a.n.a.l pouch; the Philanthus demands a full diet, or at least a notable supplement thereto, in the form of the contents of the stomach. What a hecatomb of bees must not a colony of these pirates sacrifice for their personal consumption, to say nothing of their stores of provisions! I recommend the Philanthus to the vengeance of apiarists.

For the moment we will not look further into the original causes of the crime. Let us consider matters as we know them, with all their real or apparent atrocity. In order to nourish herself the Philanthus levies tribute upon the crop of the bee. This being granted, let us consider the method of the aggressor more closely. She does not paralyse its captives according to the customary rites of the predatory insects; she kills them. Why? To the eyes of understanding the necessity of a sudden death is as clear as day. Without eviscerating the bee, which would result in the deterioration of its flesh considered as food for the larvae; without having recourse to the b.l.o.o.d.y extirpation of the stomach, the Philanthus intends to obtain its honey. By skilful manipulation, by cunning ma.s.sage, she must somehow make the bee disgorge. Suppose the bee stung in the rear of the corselet and paralysed. It is deprived of locomotion, but not of vitality. The digestive apparatus, in particular, retains in full, or at least in part, its normal energies, as is proved by the frequent dejections of paralysed victims so long as the intestine is not emptied; a fact notably exemplified by the victims of the Sphex family; helpless creatures which I have before now kept alive for forty days with the aid of a little sugared water. Well! without therapeutic means, without emetics or stomach-pumps, how is a stomach intact and in good order to be persuaded to yield up its contents? That of the bee, jealous of its treasure, will lend itself to such treatment less readily than another. Paralysed, the creature is inert; but there are always internal energies and organic resistances which will not yield to the pressure of the manipulator. In vain would the Philanthus gnaw at the throat and squeeze the flanks; the honey would not return to the mouth as long as a trace of life kept the stomach closed.

Matters are different with a corpse. The springs relax; the muscles yield; the resistance of the stomach ceases, and the vessels containing the honey are emptied by the pressure of the thief. We see, therefore, that the Philanthus is obliged to inflict a sudden death which instantly destroys the contractile power of the organs. Where shall the deadly blow be delivered? The slayer knows better than we, when she pierces the victim beneath the chin. Through the narrow breach in the throat the cerebral ganglions are reached and immediate death ensues.

The examination of these acts of brigandage is not sufficient in view of my incorrigible habit of following every reply by another query, until the granite wall of the unknowable rises before me. Although the Philanthus is skilled in forcing the bee to disgorge, in emptying the crop distended with honey, this diabolical skill cannot be merely an alimentary resource, above all when in common with other insects she has access to the refectory of the flowers. I cannot regard her talents as inspired solely by the desire of a meal obtained by the labour of emptying the stomach of another insect. Something must surely escape us here: the real reason for emptying the stomach. Perhaps a respectable reason is concealed by the horrors I have recorded. What is it?

Every one will understand the vagueness which fills the observer's mind in respect of such a question as this. The reader has the right to be doubtful. I will spare him my suspicions, my gropings for the truth, and the checks encountered in the search, and give him the results of my long inquiry. Everything has its appropriate and harmonious reason. I am too fully persuaded of this to believe that the Philanthus commits her profanation of corpses merely to satisfy her appet.i.te. What does the empty stomach mean? May it not--Yes!--But, after all, who knows? Well, let us follow up the scent.

The first care of the mothers is the welfare of the family. So far all we know of the Philanthus concerns her talent for murder. Let us consider her as a mother. We have seen her hunt on her own account; let us now watch her hunt for her offspring, for the race. Nothing is simpler than to distinguish between the two kinds of hunting. When the insect wants a few good mouthfuls of honey and nothing else, she abandons the bee contemptuously when she has emptied its stomach. It is so much valueless waste, which will shrivel where it lies and be dissected by ants. If, on the other hand, she intends to place it in the larder as a provision for her larvae, she clasps it with her two intermediate legs, and, walking on the other four, drags it to and fro along the edge of the bell-gla.s.s in search of an exit so that she may fly off with her prey. Having recognised the circular wall as impa.s.sable, she climbs its sides, now holding the bee in her mandibles by the antennae, clinging as she climbs to the vertical polished surface with all six feet. She gains the summit of the gla.s.s, stays for a little while in the flask-like cavity of the terminal b.u.t.ton or handle, returns to the ground, and resumes her circuit of the gla.s.s and her climbing, relinquis.h.i.+ng the bee only after an obstinate attempt to escape with it.

The persistence with which the Philanthus retains her clasp upon the enc.u.mbering burden shows plainly that the game would go straight to the larder were the insect at liberty.

Those bees intended for the larvae are stung under the chin like the others; they are true corpses; they are manipulated, squeezed, exhausted of their honey, just as the others. There is no difference in the method of capture nor in their after-treatment.

As captivity might possibly result in a few anomalies of action, I decided to inquire how matters went forward in the open. In the neighbourhood of some colonies of Philanthidae I lay in wait, watching for perhaps a longer time than the question justified, as it was already settled by what occurred in captivity. My scrupulous watching at various times was rewarded. The majority of the hunters immediately entered their nests, carrying the bees pressed against their bodies; some halted on the neighbouring undergrowth; and these I saw treating the bee in the usual manner, and lapping the honey from its mouth. After these preparations the corpse was placed in the larder. All doubt was thus destroyed: the bees provided for the larvae are previously carefully emptied of their honey.

Since we are dealing with the subject, let us take the opportunity of inquiring into the customs of the Philanthus in a state of freedom.

Making use of her victims when absolutely lifeless, so that they would putrefy in the course of a few days, this hunter of bees cannot adopt the customs of certain insects which paralyse their prey, and fill their cellars before laying an egg. She must surely be obliged to follow the method of the Bembex, whose larva receives, at intervals, the necessary nourishment; the amount increasing as the larva grows. The facts confirm this deduction. I spoke just now of the tediousness of my watching when watching the colonies of the Philanthus. It was perhaps even more tedious than when I was keeping an eye upon the Bembex. Before the burrows of _Cerceris tuberculus_ and other devourers of the weevil, and before that of the yellow-winged Sphex, the slayer of crickets, there is plenty of distraction, owing to the busy movements of the community.

The mothers have scarcely entered the nest before they are off again, returning quickly with fresh prey, only to set out once more. The going and coming is almost continuous until the storehouse is full.

The burrows of the Philanthus know nothing of such animation, even in a populous colony. In vain my vigils prolonged themselves into whole mornings or afternoons, and only very rarely does the mother who has entered with a bee set forth upon a second expedition. Two captures by the same huntress is the most that I have seen in my long watches. Once the family is provided with sufficient food for the moment the mother postpones further hunting trips until hunting becomes necessary, and busies herself with digging and burrowing in her underground dwelling.

Little cells are excavated, and I see the rubbish from them gradually pushed up to the surface. With that exception there is no sign of activity; it is as though the burrow were deserted.

To lay the nest bare is not easy. The burrow penetrates to a depth of about three feet in a compact soil; sometimes in a vertical, sometimes in a horizontal direction. The spade and pick, wielded by hands more vigorous but less expert than my own, are indispensable; but the conduct of the excavation is anything but satisfactory. At the extremity of the long gallery--it seems as though the straw I use for sounding would never reach the end--we finally discover the cells, egg-shaped cavities with the longer axis horizontal. Their number and their mutual disposition escape me.

Some already contain the coc.o.o.n--slender and translucid, like that of the Cerceris, and, like it, recalling the shape of certain h.o.m.oeopathic phials, with oval bodies surmounted by a tapering neck.

By the extremity of the neck, which is blackened and hardened by the dejecta of the larvae, the coc.o.o.n is fixed to the end of the cell without any other support. It reminds one of a short club, planted by the end of the handle, in a line with the horizontal axis of the cell. Other cells contain the larva in a stage more or less advanced. The grub is eating the last victim proffered; around it lie the remains of food already consumed. Others, again, show me a bee, a single bee, still intact, and having an egg deposited on the under-side of the thorax. This bee represents the first instalment of rations; others will follow as the grub matures. My expectations are thus confirmed; as with Bembex, slayer of Diptera, so Philanthus, killer of bees, lays her egg upon the first body stored, and completes, at intervals, the provisioning of the cells.

The problem of the dead bee is elucidated; there remains the other problem, of incomparable interest--Why, before they are given over to the larvae, are the bees robbed of their honey? I have said, and I repeat, that the killing and emptying of the bee cannot be explained solely by the gluttony of the Philanthus. To rob the worker of its booty is nothing; such things are seen every day; but to slaughter it in order to empty its stomach--no, gluttony cannot be the only motive. And as the bees placed in the cells are squeezed dry no less than the others, the idea occurs to me that as a beefsteak garnished with _confitures_ is not to every one's taste, so the bee sweetened with honey may well be distasteful or even harmful to the larvae of the Philanthus. What would the grub do if, replete with blood and flesh, it were to find under its mandibles the honey-bag of the bee?--if, gnawing at random, it were to open the bees stomach and so drench its game with syrup? Would it approve of the mixture? Would the little ogre pa.s.s without repugnance from the gamey flavour of a corpse to the scent of flowers? To affirm or deny is useless. We must see. Let us see.

I take the young larvae of the Philanthus, already well matured, but instead of serving them with the provisions buried in their cells I offer them game of my own catching--bees that have filled themselves with nectar among the rosemary bushes. My bees, killed by crus.h.i.+ng the head, are thankfully accepted, and at first I see nothing to justify my suspicions. Then my nurslings languish, show themselves disdainful of their food, give a negligent bite here and there, and finally, one and all, die beside their uncompleted meal. All my attempts miscarry; not once do I succeed in rearing my larvae as far as the stage of spinning the coc.o.o.n. Yet I am no novice in my duties as dry-nurse. How many pupils have pa.s.sed through my hands and have reached the final stage in my old sardine-boxes as well as in their native burrows! I shall draw no conclusions from this check, which my scruples may attribute to some unknown cause. Perhaps the atmosphere of my cabinet and the dryness of the sand serving them for a bed have been too much for my nurslings, whose tender skins are used to the warm moisture of the subsoil. Let us try another method.

To decide positively whether honey is or is not repugnant to the grubs of the Philanthus was hardly practicable by the method just explained.

The first meals consisted of flesh, and after that nothing in particular occurred. The honey is encountered later, when the bee is largely consumed. If hesitation and repugnance were manifested at this point they came too late to be conclusive; the sickness of the larvae might be due to other causes, known or unknown. We must offer honey at the very beginning, before artificial rearing has spoilt the grub's appet.i.te. To offer pure honey would, of course, be useless; no carnivorous creature would touch it, even were it starving. I must spread the honey on meat; that is, I must smear the dead bee with honey, lightly varnis.h.i.+ng it with a camel's-hair brush.

Under these conditions the problem is solved with the first few mouthfuls. The grub, having bitten on the honeyed bee, draws back as though disgusted; hesitates for a long time; then, urged by hunger, begins again; tries first on one side, then on another; in the end it refuses to touch the bee again. For a few days it pines upon its rations, which are almost intact, then dies. As many as are subjected to the same treatment perish in the same way.

Do they simply die of hunger in the presence of food which their appet.i.tes reject, or are they poisoned by the small amount of honey absorbed at the first bites? I cannot say; but, whether poisonous or merely repugnant, the bee smeared with honey is always fatal to them; a fact which explains more clearly than the unfavourable circ.u.mstances of the former experiment my lack of success with the freshly killed bees.

This refusal to touch honey, whether poisonous or repugnant, is connected with principles of alimentation too general to be a gastronomic peculiarity of the Philanthus grub. Other carnivorous larvae--at least in the series of the Hymenoptera--must share it. Let us experiment. The method need not be changed. I exhume the larvae when in a state of medium growth, to avoid the vicissitudes of extreme youth; I collect the bodies of the grubs and insects which form their natural diet and smear each body with honey, in which condition I return them to the larvae. A distinction is apparent: all the larvae are not equally suited to my experiment. Those larvae must be rejected which are nourished upon one single corpulent insect, as is that of the Scolia.

The grub attacks its prey at a determined point, plunges its head and neck into the body of the insect, skilfully divides the entrails in order to keep the remains fresh until its meal is ended, and does not emerge from the opening until all is consumed but the empty skin.

To interrupt the larva with the object of smearing the interior of its prey with honey is doubly objectionable; I might extinguish the lingering vitality which keeps putrefaction at bay in the victim, and I might confuse the delicate art of the larva, which might not be able to recover the lode at which it was working or to distinguish between those parts which are lawfully and properly eaten and those which must not be consumed until a later period. As I have shown in a previous volume, the grub of the Scolia has taught me much in this respect. The only larvae acceptable for this experiment are those which are fed on a number of small insects, which are attacked without any special art, dismembered at random, and quickly consumed. Among such larvae I have experimented with those provided by chance--those of various Bembeces, fed on Diptera; those of the Palaris, whose diet consists of a large variety of Hymenoptera; those of the Tachytus, provided with young crickets; those of the Odynerus, fed upon larvae of the Chrysomela; those of the sand-dwelling Cerceris, endowed with a hecatomb of weevils. As will be seen, both consumers and consumed offer plenty of variety. Well, in every case their proper diet, seasoned with honey, is fatal. Whether poisoned or disgusted, they all die in a few days.

A strange result! Honey, the nectar of the flowers, the sole diet of the apiary under its two forms and the sole nourishment of the predatory insect in its adult phase, is for the larva of the same insect an object of insurmountable disgust, and probably a poison. The transfiguration of the chrysalis surprises me less than this inversion of the appet.i.te.

What change occurs in the stomach of the insect that the adult should pa.s.sionately seek that which the larva refuses under peril of death? It is no question of organic debility unable to support a diet too substantial, too hard, or too highly spiced. The grubs which consume the larva of the Cetoniae, for example (the Rose-chafers), those which feed upon the leathery cricket, and those whose diet is rich in nitrobenzine, must a.s.suredly have complacent gullets and adaptable stomachs. Yet these robust eaters die of hunger or poison for no greater cause than a drop of syrup, the lightest diet imaginable, adapted to the weakness of extreme youth, and a delicacy to the adult! What a gulf of obscurity in the stomach of a miserable worm!

These gastronomic experiments called for a counter-proof. The carnivorous grub is killed by honey. Is the honey-fed grub, inversely, killed by carnivorous diet? Here, again, we must make certain exceptions, observe a certain choice, as in the previous experiments. It would obviously be courting a flat refusal to offer a heap of young crickets to the larvae of the Anthophorus and the Osmia, for example; the honey-fed grub would not bite such food. It would be absolutely useless to make such an experiment. We must find the equivalent of the bee smeared with honey; that is, we must offer the larva its ordinary food with a mixture of animal matter added. I shall experiment with alb.u.men, as provided by the egg of the hen; alb.u.men being an isomer of fibrine, which is the princ.i.p.al element of all flesh diet.

_Osmia tricornis_ will lend itself to my experiment better than any other insect on account of its dry honey, or bee-bread, which is largely formed of flowery pollen. I knead it with the alb.u.men, graduating the dose of the latter so that its weight largely exceeds that of the bee-bread. Thus I obtain pastes of various degrees of consistency, but all firm enough to support the larva without danger of immersion. With too fluid a mixture there would be a danger of death by drowning.

Finally, on each cake of alb.u.minous paste I install a larva of medium growth.

This diet is not distasteful; far from it. The grubs attack it without hesitation and devour it with every appearance of a normal appet.i.te.

Matters could not go better if the food had not been modified according to my recipes. All is eaten; even the portions which I feared contained an excessive proportion of alb.u.men. Moreover--a matter of still greater importance--the larvae of the Osmia fed in this manner attain their normal growth and spin their coc.o.o.ns, from which adults issue in the following year. Despite the alb.u.minous diet the cycle of evolution completes itself without mishap.

What are we to conclude from all this? I confess I am embarra.s.sed. _Omne vivum ex ovo_, says the physiologist. All animals are carnivorous in their first beginnings; they are formed and nourished at the expense of the egg, in which alb.u.men predominates. The highest, the mammals, adhere to this diet for a considerable time; they live by the maternal milk, rich in casein, another isomer of alb.u.men. The gramnivorous nestling is fed first upon worms and grubs, which are best adapted to the delicacy of its stomach; many newly born creatures among the lower orders, being immediately left to their own devices, live on animal diet. In this way the original method of alimentation is continued--the method which builds flesh out of flesh and makes blood out of blood with no chemical processes but those of simple reconstruction. In maturity, when the stomach is more robust, a vegetable diet may be adopted, involving a more complex chemistry, although the food itself is more easily obtained. To milk succeeds fodder; to the worm, seeds and grain; to the dead or paralysed insects of the natal burrow, the nectar of flowers.

Here is a partial explanation of the double system of the Hymenoptera with their carnivorous larvae--the system of dead or paralysed insects followed by honey. But here the point of interrogation, already encountered elsewhere, erects itself once again. Why is the larva of the Osmia, which thrives upon alb.u.men, actually fed upon honey during its early life? Why is a vegetable diet the rule in the hives of bees from the very commencement, when the other members of the same series live upon animal food?

If I were a "transformist" how I should delight in this question! Yes, I should say: yes, by the fact of its germ every animal is originally carnivorous. The insect in particular makes a beginning with alb.u.minoid materials. Many larvae adhere to the alimentation present in the egg, as do many adult insects also. But the struggle to fill the belly, which is actually the struggle for life, demands something better than the precarious chances of the chase. Man, at first an eager hunter of game, collected flocks and became a shepherd in order to profit by his possessions in time of dearth. Further progress inspired him to till the earth and sow; a method which a.s.sured him of a certain living. Evolution from the defective to the mediocre, and from the mediocre to the abundant, has led to the resources of agriculture.

The lower animals have preceded us on the way of progress. The ancestors of the Philanthus, in the remote ages of the lacustrian tertiary formations, lived by capturing prey in both phases--both as larvae and as adults; they hunted for their own benefit as well as for the family.

They did not confine themselves to emptying the stomach of the bee, as do their descendants to-day; they devoured the victim entire. From beginning to end they remained carnivorous. Later there were fortunate innovators, whose race supplanted the more conservative element, who discovered an inexhaustible source of nourishment, to be obtained without painful search or dangerous conflict: the saccharine exudation of the flowers. The wasteful system of living upon prey, by no means favourable to large populations, has been preserved for the feeble larvae; but the vigorous adult has abandoned it for an easier and more prosperous existence. Thus the Philanthus of our own days was gradually developed; thus was formed the double system of nourishment practised by the various predatory insects which we know.

The bee has done still better; from the moment of leaving the egg it dispenses completely with chance-won aliments. It has invented honey, the food of its larvae. Renouncing the chase for ever, and becoming exclusively agricultural, this insect has acquired a degree of moral and physical prosperity that the predatory species are far from sharing.

Hence the flouris.h.i.+ng colonies of the Anthophorae, the Osmiae, the Eucerae, the Halicti, and other makers of honey, while the hunters of prey work in isolation; hence the societies in which the bee displays its admirable talents, the supreme expression of instinct.

This is what I should say if I were a "transformist." All this is a chain of highly logical deductions, and it hangs together with a certain air of reality, such as we like to look for in a host of "transformist"

arguments which are put forward as irrefutable. Well, I make a present of my deductive theory to whosoever desires it, and without the least regret; I do not believe a single word of it, and I confess my profound ignorance of the origin of the twofold system of diet.