Bramble-Bees and Others Part 8

Coming from Germany, this theory cannot but inspire me with profound distrust. As it has been given acceptance, with rash precipitancy, in standard works, I will overcome my reluctance to devoting my attention to Teutonic ideas and will submit it not to the test of argument, which can always be met by an opposite argument, but to the unanswerable test of facts.

For this optional fertilization, determining the s.e.x, the mother's organism requires a seminal reservoir which distils its drop of sperm upon the egg contained in the oviduct and thus gives it a feminine character, or else leaves it its original character, the male character, by refusing it that baptism. This reservoir exists in the Hive-bee.

Do we find a similar organ in the other Hymenoptera, whether honey-gatherers or hunters? The anatomical treatises are either silent on this point or, without further enquiry, apply to the order as a whole the data provided by the Hive-bee, however much she differs from the ma.s.s of Hymenoptera owing to her social habits, her sterile workers and especially her tremendous fertility, extending over so long a period.

I at first doubted the universal presence of this spermatic receptacle, having failed to find it under my scalpel in my former investigations into the anatomy of the Sphex-wasps and some other game-hunters. But this organ is so delicate and so small that it very easily escapes the eye, especially when our attention is not specially directed in search of it; and, even when we are looking for it and it only, we do not always succeed in discovering it. We have to find a globule attaining in many cases hardly as much as a millimetre (About one-fiftieth of an inch.--Translator's Note.) in diameter, a globule headed amidst a tangle of air-ducts and fatty patches, of which it shares the colour, a dull white. Then again, the merest slip of the forceps is enough to destroy it. My first investigations, therefore, which concerned the reproductive apparatus as a whole, might very well have allowed it to pa.s.s unperceived.

In order to know the rights of the matter once and for all, as the anatomical treatises taught me nothing, I once more fixed my microscope on its stand and rearranged my old dissecting-tank, an ordinary tumbler with a cork disk covered with black satin. This time, not without a certain strain on my eyes, which are already growing tired, I succeeded in finding the said organ in the Bembex-wasps, the Halicti (Cf.

Chapters 12 to 14 of the present volume.--Translator's Note.), the Carpenter-bees, the b.u.mble-bees, the Andrenae (A species of Burrowing Bees.--Translator's Note.) and the Megachiles. (Or Leaf-cutting Bees.

Cf. Chapter 8 of the present volume.--Translator's Note.) I failed in the case of the Osmiae, the Chalicodomae and the Anthophorae. Is the organ really absent? Or was there want of skill on my part? I lean towards want of skill and admit that all the game-hunting and honey-gathering Hymenoptera possess a seminal receptacle, which can be recognized by its contents, a quant.i.ty of spiral spermatozoids whirling and twisting on the slide of the microscope.

This organ once accepted, the German theory becomes applicable to all the Bees and all the Wasps. When copulating, the female receives the seminal fluid and holds it stored in her receptacle. From that moment, the two procreating elements are present in the mother at one and the same time: the female element, the ovule; and the male element, the spermatozoid. At the egg-layer's will, the receptacle bestows a tiny drop of its contents upon the matured ovule, when it reaches the oviduct, and you have a female egg; or else it withholds its spermatozoids and you have an egg that remains male, as it was at first.

I readily admit it: the theory is very simple, lucid and seductive. But is it correct? That is another question.

One might begin by reproaching it with making a singular exception to one of the most general rules. Which of us, casting his eyes over the whole zoological progression, would dare to a.s.sert that the egg is originally male and that it becomes female by fertilization? Do not the two s.e.xes both call for the a.s.sistance of the fertilizing element? If there be one undoubted truth, it is certainly that. We are, it is true, told very curious things about the Hive-bee. I will not discuss them: this Bee stands too far outside the ordinary limits; and then the facts a.s.serted are far from being accepted by everybody. But the non-social Bees and the predatory insects have nothing special about their laying.

Then why should they escape the common rule, which requires that every living creature, male as well as female, should come from a fertilized ovule? In its most solemn act, that of procreation, life is one and uniform; what it does here it does there and there and everywhere. What!

The sporule of a sc.r.a.p of moss requires an antherozoid before it is fit to germinate; and the ovule of a Scolia, that proud huntress, can dispense with the equivalent in order to hatch and produce a male? These new-fangled theories seem to me to have very little value.

One might also bring forward the case of the Three-p.r.o.nged Osmia, who distributes the two s.e.xes without any order in the hollow of her reed.

What singular whim is the mother obeying when, without decisive motive, she opens her seminal phial at haphazard to anoint a female egg, or else keeps it closed, also at haphazard, to allow a male egg to pa.s.s unfertilized? I could imagine impregnation being given or withheld for periods of some duration; but I cannot understand impregnation and non-impregnation following upon each other anyhow, in any sort of order, or rather with no order it all. The mother has just fertilized an egg.

Why should she refuse to fertilize the next, when neither the provisions nor the lodgings differ in the smallest respect from the previous provisions and lodgings? These capricious alternations, so unreasonable and so exceedingly erratic, are scarcely appropriate to an act of such importance.

But I promised not to argue and I find myself arguing. My reasoning is too fine for dull wits. I will pa.s.s on and come to the brutal fact, the real sledge-hammer blow.

Towards the end of the Bee's operations, in the first week of June, the last acts of the Three-horned Osmia become so exceptionally interesting that I made her the object of redoubled observation. The swarm at this time is greatly reduced in numbers. I have still some thirty laggards, who continue very busy, though their work is in vain. I see some very conscientiously stopping up the entrance to a tube or a Snail-sh.e.l.l in which they have laid nothing at all. Others are closing the home after only building a few part.i.tions, or even mere attempts at part.i.tions.

Some are placing at the back of a new gallery a pinch of pollen which will benefit n.o.body and then shutting up the house with an earthen stopper as thick, as carefully made as though the safety of a family depended on it. Born a worker, the Osmia must die working. When her ovaries are exhausted, she spends the remainder of her strength on useless works: part.i.tions, plugs, pollen-heaps, all destined to be left unemployed. The little animal machine cannot bring itself to be inactive even when there is nothing more to be done. It goes on working so that its last vibrations of energy may be used up in fruitless labour. I commend these aberrations to the staunch supporters of reasoning-powers in the animal.

Before coming to these useless tasks, my laggards have laid their last eggs, of which I know the exact cells, the exact dates. These eggs, as far as the microscopes can tell, differ in no respect from the others, the older ones. They have the same dimensions, the same shape, the same glossiness, the same look of freshness. Nor are their provisions in any way peculiar, being very well suited to the males, who conclude the laying. And yet these last eggs do not hatch: they wrinkle, fade and wither on the pile of food. In one case, I count three or four sterile eggs among the last lot laid; in another, I find two or only one.

Elsewhere in the swarm, fertile eggs have been laid right up to the end.

Those sterile eggs, stricken with death at the moment of their birth, are too numerous to be ignored. Why do they not hatch like the other eggs, which outwardly they resemble in every respect? They have received the same attention from the mother and the same portion of food. The searching microscope shows me nothing in them to explain the fatal ending.

To the unprejudiced mind, the answer is obvious. Those eggs do not hatch because they have not been fertilized. Any animal or vegetable egg that had not received the life-giving impregnation would perish in the same way. No other answer is possible. It is no use talking of the distant period of the laying: eggs of the same period laid by other mothers, eggs of the same date and likewise the final ones of a laying, are perfectly fertile. Once more, they do not hatch because they were not fertilized.

And why were they not fertilized? Because the seminal receptacle, so tiny, so difficult to see that it sometimes escaped me despite all my scrutiny, had exhausted its contents. The mothers in whom this receptacle retained a remnant of sperm to the end had their last eggs as fertile as the first; the others, whose seminal reservoir was exhausted too soon, had their last-born stricken with death. All this seems to me as clear as daylight.

If the unfertilized eggs perish without hatching, those which hatch and produce males are therefore fertilized; and the German theory falls to the ground.

Then what explanation shall I give of the wonderful facts which I have set forth? Why, none, absolutely none. I do not explain facts, I relate them. Growing daily more sceptical of the interpretations suggested to me and more hesitating as to those which I may have to suggest myself, the more I observe and experiment, the more clearly I see rising out of the black mists of possibility an enormous note of interrogation.

Dear insects, my study of you has sustained me and continues to sustain me in my heaviest trials. I must take leave of you for to-day. The ranks are thinning around me and the long hopes have fled. Shall I be able to speak to you again? (This is the closing paragraph of Volume 3 of the "Souvenirs entomologiques," of which the author has lived to publish seven more volumes, containing over 2,500 pages and nearly 850,000 words.--Translator's Note.)

CHAPTER 6. INSTINCT AND DISCERNMENT.

The Pelopaeus (A Mason-wasp forming the subject of essays which have not yet been published in English.--Translator's Note.) gives us a very poor idea of her intellect when she plasters up the spot in the wall where the nest which I have removed used to stand, when she persists in cramming her cell with Spiders for the benefit of an egg no longer there and when she dutifully closes a cell which my forceps has left empty, extracting alike germ and provisions. The Mason-bees (Cf. "The Mason-bees": chapter 7.--Translator's Note.), the caterpillar of the Great Peac.o.c.k Moth (Cf. "Social Life in the Insect World" by J.H. Fabre, translated by Bernard Miall: chapter 14.--Translator's Note.) and many others, when subjected to similar tests, are guilty of the same illogical behaviour: they continue, in the normal order, their series of industrious actions, though an accident has now rendered them all useless. Just like millstones unable to cease revolving though there be no corn left to grind, let them once be given the compelling power and they will continue to perform their task despite its futility. Are they then machines? Far be it from me to think anything so foolish.

It is impossible to make definite progress on the shifting sands of contradictory facts: each step in our interpretation may find us embogged. And yet these facts speak so loudly that I do not hesitate to translate their evidence as I understand it. In insect mentality, we have to distinguish two very different domains. One of these is INSTINCT properly so called, the unconscious impulse that presides over the most wonderful part of what the creature achieves. Where experience and imitation are of absolutely no avail, instinct lays down its inflexible law. It is instinct and instinct alone that makes the mother build for a family which she will never see; that counsels the storing of provisions for the unknown offspring; that directs the sting towards the nerve-centres of the prey and skilfully paralyses it, so that the game may keep good; that instigates, in fine, a host of actions wherein shrewd reason and consummate science would have their part, were the creature acting through discernment.

This faculty is perfect of its kind from the outset, otherwise the insect would have no posterity. Time adds nothing to it and takes nothing from it. Such as it was for a definite species, such it is to-day and such it will remain, perhaps the most settled zoological characteristic of them all. It is not free nor conscious in its practice, any more than is the faculty of the stomach for digestion or that of the heart for pulsation. The phases of its operations are predetermined, necessarily entailed one by another; they suggest a system of clock-work wherein one wheel set in motion brings about the movement of the next. This is the mechanical side of the insect, the fatum, the only thing which is able to explain the monstrous illogicality of a Pelopaeus when misled by my artifices. Is the Lamb when it first grips the teat a free and conscious agent, capable of improvement in its difficult art of taking nourishment? The insect is no more capable of improvement in its art, more difficult still, of giving nourishment.

But, with its hide-bound science ignorant of itself, pure insect, if it stood alone, would leave the insect unarmed in the perpetual conflict of circ.u.mstances. No two moments in time are identical; though the background remain the same, the details change; the unexpected rises on every side. In this bewildering confusion, a guide is needed to seek, accept, refuse and select; to show preference for this and indifference to that; to turn to account, in short, anything useful that occasion may offer. This guide the insect undoubtedly possesses, to a very manifest degree. It is the second province of its mentality. Here it is conscious and capable of improvement by experience. I dare not speak of this rudimentary faculty as intelligence, which is too exalted a t.i.tle: I will call it DISCERNMENT. The insect, in exercising its highest gifts, discerns, differentiates between one thing and another, within the sphere of its business, of course; and that is about all.

As long as we confound acts of pure instinct and acts of discernment under the same head, we shall fall back into those endless discussions which embitter controversy without bringing us one step nearer to the solution of the problem. Is the insect conscious of what it does? Yes and no. No, if its action is in the province of instinct; yes, if the action is in that of discernment. Are the habits of an insect capable of modification? No, decidedly not, if the habit in question belongs to the province of instinct; yes, if it belongs to that of discernment. Let us state this fundamental distinction more precisely by the aid of a few examples.

The Pelopaeus builds her cells with earth already softened, with mud.

Here we have instinct, the unalterable characteristic of the worker.

She has always built in this way and always will. The pa.s.sing ages will never teach her, neither the struggle for life nor the law of selection will ever induce her to imitate the Mason-bee and collect dry dust for her mortar. This mud nest needs a shelter against the rain. The hiding-place under a stone suffices at first. But should she find something better, the potter takes possession of that something better and instals herself in the home of man. (The Pelopaeus builds in the fire-places of houses.--Translator's Note.) There we have discernment, the source of some sort of capacity for improvement.

The Pelopaeus supplies her larvae with provisions in the form of Spiders. There you have instinct. The climate, the longitude or lat.i.tude, the changing seasons, the abundance or scarcity of game introduce no modification into this diet, though the larva shows itself satisfied with other fare provided by myself. Its forebears were brought up on Spiders; their descendants consumed similar food; and their posterity again will know no other. Not a single circ.u.mstance, however favourable, will ever persuade the Pelopaeus that young Crickets, for instance, are as good as Spiders and that her family would accept them gladly. Instinct binds her down to the national diet.

But, should the Epeira (The Weaving or Garden Spider. Cf. "The Life of the Spider" by J. Henri Fabre translated by Alexander Teixeira de Mattos; chapters 9 to 14 and appendix.--Translator's Note.), the favourite prey, be lacking, must the Pelopaeus therefore give up foraging? She will stock her warehouses all the same, because any Spider suits her. There you have discernment, whose elasticity makes up, in certain circ.u.mstances, for the too-great rigidity of instinct. Amid the innumerable variety of game, the huntress is able to discern between what is Spider and what is not; and, in this way, she is always prepared to supply her family, without quitting the domain of her instinct.

The Hairy Ammophila gives her larva a single caterpillar, a large one, paralysed by as many p.r.i.c.ks of her sting as it has nervous centres in its thorax and abdomen. Her surgical skill in subduing the monster is instinct displayed in a form which makes short work of any inclination to see in it an acquired habit. In an art that can leave no one to practise it in the future unless that one be perfect at the outset, of what avail are happy chances, atavistic tendencies, the mellowing hand of time? But the grey caterpillar, sacrificed one day, may be succeeded on another day by a green, yellow or striped caterpillar. There you have discernment, which is quite capable of recognizing the regulation prey under very diverse garbs.

The Megachiles build their honey-jars with disks cut out of leaves; certain Anthidia make felted cotton wallets; others fashion pots out of resin. There you have instinct. Will any rash mind ever conceive the singular idea that the Leaf-cutter might very well have started working in cotton, that the cotton-wool-worker once thought or will one day think of cutting disks out of the leaves of the lilac- and the rose-tree, that the resin-kneader began with clay? Who would dare to indulge in any such theories? Each Bee has her art, her medium, to which she strictly confines herself. The first has her leaves; the second her wadding; the third her resin. None of these guilds has ever changed trades with another; and none ever will. There you have instinct, keeping the workers to their specialities. There are no innovations in their workshops, no recipes resulting from experiment, no ingenious devices, no progress from indifferent to good, from good to excellent.

To-day's method is the facsimile of yesterday's; and to-morrow will know no other.

But, though the manufacturing-process is invariable, the raw material is subject to change. The plant that supplies the cotton differs in species according to the locality; the bush out of whose leaves the pieces will be cut is not the same in the various fields of operation; the tree that provides the resinous putty may be a pine, a cypress, a juniper, a cedar or a spruce, all very different in appearance. What will guide the insect in its gleaning? Discernment.

These, I think, are sufficient details of the fundamental distinction to be drawn in the insect's mentality; the distinction, that is, between instinct and discernment. If people confuse these two provinces, as they nearly always do, any understanding becomes impossible; the last glimmer of light disappears behind the clouds of interminable discussions. From an industrial point of view, let us look upon the insect as a worker thoroughly versed from birth in a craft whose essential principles never vary; let us grant that unconscious worker a gleam of intelligence which will permit it to extricate itself from the inevitable conflict of attendant circ.u.mstances; and I think that we shall have come as near to the truth as the state of our knowledge will allow for the moment.

Having thus a.s.signed a due share both to instinct and the aberrations of instinct when the course of its different phases is disturbed, let us see what discernment is able to do in the selection of a site for the nest and materials for building it; and, leaving the Pelopaeus, upon whom it is useless to dwell any longer, let us consider other examples, picked from among those richest in variations.

The Mason-bee of the Sheds (Chalicodoma rufitarsis, PEREZ) well deserves the name which I have felt justified in giving her from her habits: she settles in numerous colonies in our sheds, on the lower surface of the tiles, where she builds huge nests which endanger the solidity of the roof. Nowhere does the insect display a greater zeal for work than in one of these colossal cities, an estate which is constantly increasing as it pa.s.ses down from one generation to another; nowhere does it find a better workshop for the exercise of its industry. Here it has plenty of room: a quiet resting-place, sheltered from damp and from excess of heat or cold.

But the s.p.a.cious domain under the tiles is not within the reach of all: sheds with free access and the proper sunny aspect are pretty rare.

These sites fall only to the favoured of fortune. Where will the others take up their quarters? More or less everywhere. Without leaving the house in which I live, I can enumerate stone, wood, gla.s.s, metal, paint and mortar as forming the foundation of the nests. The green-house with its furnace heat in the summer and its bright light, equalling that outside, is fairly well-frequented. The Mason-bee hardly ever fails to build there each year, in squads of a few dozen apiece, now on the gla.s.s panes, now on the iron bars of the framework. Other little swarms settle in the window embrasures, under the projecting ledge of the front door or in the cranny between the wall and an open shutter. Others again, being perhaps of a morose disposition, flee society and prefer to work in solitude, one in the inside of a lock or of a pipe intended to carry the rain-water from the leads; another in the mouldings of the doors and windows or in the crude ornamentation of the stone-work. In short, the house is made use of all round, provided that the shelter be an out-of-door one; for observe that the enterprising invader, unlike the Pelopaeus, never penetrates inside our dwellings. The case of the conservatory is an exception more apparent than real: the gla.s.s building, standing wide open throughout the summer, is to the Mason-bee but a shed a little lighter than the others. There is nothing here to arouse the distrust with which anything indoors or shut up inspires her. To build on the threshold of an outer door, or to usurp its lock, a hiding-place to her fancy, is all that she allows herself; to go any farther is an adventure repugnant to her taste.

Lastly, in the case of all these dwellings, the Mason-bee is man's free tenant; her industry makes use of the products of our own industry. Can she have no other establishments? She has, beyond a doubt; she possesses some constructed on the ancient plan. On a stone the size of a man's fist, protected by the shelter of a hedge, sometimes even on a pebble in the open air, I see her building now groups of cells as large as a walnut, now domes emulating in size, shape and solidity those of her rival, the Mason-bee of the Walls.

The stone support is the most frequent, though not the only one. I have found nests, but spa.r.s.ely inhabited it is true, on the trunks of trees, in the seams of the rough bark of oaks. Among those whose support was a living plant, I will mention two that stand out above all the others.

The first was built in the lobe of a torch-thistle as thick as my leg; the second rested on a stalk of the opuntia, the Indian fig. Had the fierce armour of these two stout cactuses attracted the attention of the insect, which looked upon their tufts of spikes as furnishing a system of defence for its nest? Perhaps so. In any case, the attempt was not imitated; I never saw another installation of the kind. There is one definite conclusion to be drawn from my two discoveries. Despite the oddity of their structure, which is unparalleled among the local flora, the two American importations did not compel the insect to go through an apprenticeship of groping and hesitation. The one which found itself in the presence of those novel growths, and which was perhaps the first of its race to do so, took possession of their lobes and stalks just as it would have done of a familiar site. From the start, the fleshy plants from the New World suited it as well as the trunk of a native tree.

The Mason-bee of the Pebbles (Chalicodoma parietina) has none of this elasticity in the choice of a site. In her case, the smooth stone of the parched uplands is the almost invariable foundation of her structures.

Elsewhere, under a less clement sky, she prefers the support of a wall, which protects the nest against the prolonged snows. Lastly, the Mason-bee of the Shrubs (Chalicodoma rufescens, PEREZ) fixes her ball of clay to a twig of any ligneous plant, from the thyme, the rock-rose and the heath to the oak, the elm and the pine. The list of the sites that suit her would almost form a complete catalogue of the ligneous flora.

The variety of places wherein the insect instals itself, so eloquent of the part played by discernment in their selection, becomes still more remarkable when it is accompanied by a corresponding variety in the architecture of the cells. This is more particularly the case with the Three-horned Osmia, who, as she uses clayey materials very easily affected by the rain, requires, like the Pelopaeus, a dry shelter for her cells, a shelter which she finds ready-made and uses just as it is, after a few touches by way of sweeping and cleansing. The homes which I see her adopt are especially the sh.e.l.ls of Snails that have died under the stone-heaps and in the low, unmortared walls which support the cultivated earth of the hills in shelves or terraces. The use of Snail-sh.e.l.ls is accompanied by the no less active use of the old cells of both the Mason-bee of the Sheds and of certain Anthophorae (A.

pilipes, A. parietina and A. personata).

We must not forget the reed, which is highly appreciated when--a rare find--it appears under the requisite conditions. In its natural state, the plant with the mighty hollow cylinders is of no possible use to the Osmia, who knows nothing of the art of perforating a woody wall. The gallery of an internode has to be wide open before the insect can take possession of it. Also, the clean-cut stump must be horizontal, otherwise the rain would soften the fragile edifice of clay and soon lay it low; also, the stump must not be lying on the ground and must be kept at some distance from the dampness of the soil. We see therefore that, without the intervention of man, involuntary in the vast majority of cases and deliberate only on the experimenter's part, the Osmia would hardly ever find a reed-stump suited to the installation of her family.

It is to her a casual acquisition, a home unknown to her race before men took it into their heads to cut reeds and make them into hurdles for drying figs in the sun.

How did the work of man's pruning-knife bring about the abandonment of the natural lodging? How was the spiral staircase of the Snail-sh.e.l.l replaced by the cylindrical gallery of the reed? Was the change from one kind of house to another effected by gradual transitions, by attempts made, abandoned, resumed, becoming more and more definite in their results as generation succeeded generation? Or did the Osmia, finding the cut reed that answered her requirements, instal herself there straightway, scorning her ancient dwelling, the Snail-sh.e.l.l? These questions called for a reply; and they have received one. Let us describe how things happened.

Near Serignan are some great quarries of coa.r.s.e limestone, characteristic of the miocene formation of the Rhone valley. These have been worked for many generations. The ancient public buildings of Orange, notably the colossal frontage of the theatre whither all the intellectual world once flocked to hear Sophocles' "Oedipus Tyrannus,"

derive most of their material from these quarries. Other evidence confirms what the similarity of the hewn stone tells us. Among the rubbish that fills up the s.p.a.ces between the tiers of seats, they occasionally discover the Ma.r.s.eilles obol, a bit of silver stamped with the four-spoked wheel, or a few bronze coins bearing the effigy of Augustus or Tiberius. Scattered also here and there among the monuments of antiquity are heaps of refuse, acc.u.mulations of broken stones in which various Hymenoptera, including the Three-horned Osmia in particular, take possession of the dead Snail-sh.e.l.l.