The Wonders of Instinct Part 3

I make some chambers of suitable size in oak logs chopped in two; and each of my artificial cells receives a newly transformed Cerambyx, such as my provisions of firewood supply, when split by the wedge, in October. The two pieces are then joined and kept together with a few bands of wire. June comes. I hear a sc.r.a.ping inside my billets. Will the Capricorns come out, or not? The delivery does not seem difficult to me: there is hardly three-quarters of an inch to pierce. Not one emerges. When all is silence, I open my apparatus. The captives, from first to last, are dead. A vestige of sawdust, less than a pinch of snuff, represents all their work.

I expected more from those st.u.r.dy tools, their mandibles. But, as I have said elsewhere, the tool does not make the workman. In spite of their boring-implements, the hermits die in my cases for lack of skill.

I subject others to less arduous tests. I enclose them in s.p.a.cious reed-stumps, equal in diameter to the natal cell. The obstacle to be pierced is the natural diaphragm, a yielding part.i.tion two or three millimetres thick. (.078 to .117 inch.--Translator's Note.) Some free themselves; others cannot. The less vibrant ones succ.u.mb, stopped by the frail barrier. What would it be if they had to pa.s.s through a thickness of oak?

We are now persuaded: despite his stalwart appearance, the Capricorn is powerless to leave the tree-trunk by his unaided efforts. It therefore falls to the worm, to the wisdom of that bit of an intestine, to prepare the way for him. We see renewed, in another form, the feats of prowess of the Anthrax, whose pupa, armed with trepans, bores through rock on the feeble Fly's behalf. Urged by a presentiment that to us remains an unfathomable mystery, the Cerambyx-grub leaves the inside of the oak, its peaceful retreat, its una.s.sailable stronghold, to wriggle towards the outside, where lives the foe, the Woodp.e.c.k.e.r, who may gobble up the succulent little sausage. At the risk of its life, it stubbornly digs and gnaws to the very bark, of which it leaves no more intact than the thinnest film, a slender screen. Sometimes, even, the rash one opens the window wide.

This is the Capricorn's exit-hole. The insect will have but to file the screen a little with its mandibles, to b.u.mp against it with its forehead, in order to bring it down; it will even have nothing to do when the window is free, as often happens. The unskilled carpenter, burdened with his extravagant head-dress, will emerge from the darkness through this opening when the summer heats arrive.

After the cares of the future come the cares of the present. The larva, which has just opened the aperture of escape, retreats some distance down its gallery and, in the side of the exit-way, digs itself a transformation-chamber more sumptuously furnished and barricaded than any that I have ever seen. It is a roomy niche, shaped like a flattened ellipsoid, the length of which reaches eighty to a hundred millimetres.

(3 to 4 inches.--Translator's Note.) The two axes of the cross-section vary: the horizontal measures twenty-five to thirty millimetres (.975 to 1.17 inch.--Translator's Note.); the vertical measures only fifteen.

(.585 inch.--Translator's Note.) This greater dimension of the cell, where the thickness of the perfect insect is concerned, leaves a certain scope for the action of its legs when the time comes for forcing the barricade, which is more than a close-fitting mummy-case would do.

The barricade in question, a door which the larva builds to exclude the dangers from without, is two-and even three-fold. Outside, it is a stack of woody refuse, of particles of chopped timber; inside, a mineral hatch, a concave cover, all in one piece, of a chalky white.

Pretty often, but not always, there is added to these two layers an inner casing of shavings. Behind this compound door, the larva makes its arrangements for the metamorphosis. The sides of the chamber are rasped, thus providing a sort of down formed of ravelled woody fibres, broken into minute shreds. The velvety matter, as and when obtained, is applied to the wall in a continuous felt at least a millimetre thick.

(.039 inch.--Translator's Note.) The chamber is thus padded throughout with a fine swan's-down, a delicate precaution taken by the rough worm on behalf of the tender pupa.

Let us hark back to the most curious part of the furnishing, the mineral hatch or inner door of the entrance. It is an elliptical skull-cap, white and hard as chalk, smooth within and knotted without, resembling more or less closely an acorn-cup. The knots show that the matter is supplied in small, pasty mouthfuls, solidifying outside in slight projections which the insect does not remove, being unable to get at them, and polished on the inside surface, which is within the worm's reach. What can be the nature of that singular lid whereof the Cerambyx furnishes me with the first specimen? It is as hard and brittle as a flake of lime-stone. It can be dissolved cold in nitric acid, discharging little gaseous bubbles. The process of solution is a slow one, requiring several hours for a tiny fragment. Everything is dissolved, except a few yellowish flocks, which appear to be of an organic nature. As a matter of fact, a piece of the hatch, when subjected to heat, blackens, proving the presence of an organic glue cementing the mineral matter. The solution becomes muddy if oxalate of ammonia be added; it then deposits a copious white precipitate. These signs indicate calcium carbonate. I look for urate of ammonia, that constantly recurring product of the various stages of the metamorphoses. It is not there: I find not the least trace of murexide.

The lid, therefore, is composed solely of carbonate of lime and of an organic cement, no doubt of an alb.u.minous character, which gives consistency to the chalky paste.

Had circ.u.mstances served me better, I should have tried to discover in which of the worm's organs the stony deposit dwells. I am however, convinced: it is the stomach, the chylific ventricle, that supplies the chalk. It keeps it separated from the food, either as original matter or as a derivative of the ammonium urate; it purges it of all foreign bodies, when the larval period comes to an end, and holds it in reserve until the time comes to disgorge it. This freestone factory causes me no astonishment: when the manufacturer undergoes his change, it serves for various chemical works. Certain Oil-beetles, such as the Sitaris, locate in it the urate of ammonia, the refuse of the transformed organism; the Sphex, the Pelopaei, the Scoliae use it to manufacture the sh.e.l.lac wherewith the silk of the coc.o.o.n is varnished. Further investigations will only swell the aggregate of the products of this obliging organ.

When the exit-way is prepared and the cell upholstered in velvet and closed with a threefold barricade, the industrious worm has concluded its task. It lays aside its tools, sheds its skin and becomes a nymph, a pupa, weakness personified, in swaddling-clothes, on a soft couch.

The head is always turned towards the door. This is a trifling detail in appearance; but it is everything in reality. To lie this way or that in the long cell is a matter of great indifference to the grub, which is very supple, turning easily in its narrow lodging and adopting whatever position it pleases. The coming Capricorn will not enjoy the same privileges. Stiffly girt in his horn cuira.s.s, he will not be able to turn from end to end; he will not even be capable of bending, if some sudden wind should make the pa.s.sage difficult. He must absolutely find the door in front of him, lest he perish in the casket. Should the grub forget this little formality, should it lie down to its nymphal sleep with its head at the back of the cell, the Capricorn is infallibly lost: his cradle becomes a hopeless dungeon.

But there is no fear of this danger: the knowledge of our bit of an intestine is too sound in things of the future for the grub to neglect the formality of keeping its head to the door. At the end of spring, the Capricorn, now in possession of his full strength, dreams of the joys of the sun, of the festivals of light. He wants to get out. What does he find before him? A heap of filings easily dispersed with his claws; next, a stone lid which he need not even break into fragments: it comes undone in one piece; it is removed from its frame with a few pushes of the forehead, a few tugs of the claws. In fact, I find the lid intact on the threshold of the abandoned cells. Last comes a second ma.s.s of woody remnants, as easy to disperse as the first. The road is now free: the Cerambyx has but to follow the s.p.a.cious vestibule, which will lead him, without the possibility of mistake, to the exit. Should the window not be open, all that he has to do is to gnaw through a thin screen: an easy task; and behold him outside, his long antennae aquiver with excitement.

What have we learnt from him? Nothing, from him; much from his grub.

This grub, so poor in sensory organs, gives us no little food for reflection with its prescience. It knows that the coming Beetle will not be able to cut himself a road through the oak and it bethinks itself of opening one for him at its own risk and peril. It knows that the Cerambyx, in his stiff armour, will never be able to turn and make for the orifice of the cell; and it takes care to fall into its nymphal sleep with its head to the door. It knows how soft the pupa's flesh will be and upholsters the bedroom with velvet. It knows that the enemy is likely to break in during the slow work of the transformation and, to set a bulwark against his attacks, it stores a calcium pap inside its stomach. It knows the future with a clear vision, or, to be accurate, behaves as though it knew it. Whence did it derive the motives of its actions? Certainly not from the experience of the senses. What does it know of the outside world? Let us repeat, as much as a bit of an intestine can know. And this senseless creature fills us with amazement! I regret that the clever logician, instead of conceiving a statue smelling a rose, did not imagine it gifted with some instinct. How quickly he would have recognized that, quite apart from sense-impressions, the animal, including man, possesses certain psychological resources, certain inspirations that are innate and not acquired!

CHAPTER 5. THE BURYING-BEETLES: THE BURIAL.

Beside the footpath in April lies the Mole, disembowelled by the peasant's spade; at the foot of the hedge the pitiless urchin has stoned to death the Lizard, who was about to don his green, pearl-embellished costume. The pa.s.ser-by has thought it a meritorious deed to crush beneath his heel the chance-met Adder; and a gust of wind has thrown a tiny unfeathered bird from its nest. What will become of these little bodies and of so many other pitiful remnants of life? They will not long offend our sense of sight and smell. The sanitary officers of the fields are legion.

An eager freebooter, ready for any task, the Ant is the first to come hastening and begin, particle by particle, to dissect the corpse. Soon the odour of the corpse attracts the Fly, the genitrix of the odious maggot. At the same time, the flattened Silpha, the glistening, slow-trotting Horn-beetle, the Dermestes, powdered with snow upon the abdomen, and the slender Staphylinus, all, whence coming no one knows, hurry hither in squads, with never-wearied zeal, investigating, probing and draining the infection.

What a spectacle, in the spring, beneath a dead Mole! The horror of this laboratory is a beautiful sight for one who is able to observe and to meditate. Let us overcome our disgust; let us turn over the unclean refuse with our foot. What a swarming there is beneath it, what a tumult of busy workers! The Silphae, with wing-cases wide and dark, as though in mourning, fly distraught, hiding in the cracks in the soil; the Saprini, of polished ebony which mirrors the sunlight, jog hastily off, deserting their workshop; the Dermestes, of whom one wears a fawn-coloured tippet, spotted with white, seek to fly away, but, tipsy with their putrid nectar, tumble over and reveal the immaculate whiteness of their bellies, which forms a violent contrast with the gloom of the rest of their attire.

What were they doing there, all these feverish workers? They were making a clearance of death on behalf of life. Transcendent alchemists, they were transforming that horrible putridity into a living and inoffensive product. They were draining the dangerous corpse to the point of rendering it as dry and sonorous as the remains of an old slipper hardened on the refuse-heap by the frosts of winter and the heats of summer. They were working their hardest to render the carrion innocuous.

Others will soon put in their appearance, smaller creatures and more patient, who will take over the relic and exploit it ligament by ligament, bone by bone, hair by hair, until the whole has been resumed by the treasury of life. All honour to these purifiers! Let us put back the Mole and go our way.

Some other victim of the agricultural labours of spring--a Shrew-mouse, Field-mouse, Mole, Frog, Adder, or Lizard--will provide us with the most vigorous and famous of these expurgators of the soil. This is the Burying-beetle, the Necrophorus, so different from the cadaveric mob in dress and habits. In honour of his exalted functions he exhales an odour of musk; he bears a red tuft at the tip of his antennae; his breast is covered with nankeen; and across his wing-cases he wears a double, scalloped scarf of vermilion. An elegant, almost sumptuous costume, very superior to that of the others, but yet lugubrious, as befits your undertaker's man.

He is no anatomical dissector, cutting his subject open, carving its flesh with the scalpel of his mandibles; he is literally a gravedigger, a s.e.xton. While the others--Silphae, Dermestes, Horn-beetles--gorge themselves with the exploited flesh, without, of course, forgetting the interests of the family, he, a frugal eater, hardly touches his booty on his own account. He buries it entire, on the spot, in a cellar where the thing, duly ripened, will form the diet of his larvae. He buries it in order to establish his progeny therein.

This h.o.a.rder of dead bodies, with his stiff and almost heavy movements, is astonishingly quick at storing away wreckage. In a shift of a few hours, a comparatively enormous animal--a Mole, for example--disappears, engulfed by the earth. The others leave the dried, emptied carca.s.s to the air, the sport of the winds for months on end; he, treating it as a whole, makes a clean job of things at once. No visible trace of his work remains but a tiny hillock, a burial-mound, a tumulus.

With his expeditious method, the Necrophorus is the first of the little purifiers of the fields. He is also one of the most celebrated of insects in respect of his psychical capacities. This undertaker is endowed, they say, with intellectual faculties approaching to reason, such as are not possessed by the most gifted of the Bees and Wasps, the collectors of honey or game. He is honoured by the two following anecdotes, which I quote from Lacordaire's "Introduction to Entomology," the only general treatise at my disposal:

"Clairville," says the author, "records that he saw a Necrophorus vespillo, who, wishing to bury a dead Mouse and finding the soil on which the body lay too hard, proceeded to dig a hole at some distance in soil more easily displaced. This operation completed, he attempted to bury the Mouse in this cavity, but, not succeeding, he flew away, returning a few moments later accompanied by four of his fellows, who a.s.sisted him to move the Mouse and bury it."

In such actions, Lacordaire adds, we cannot refuse to admit the intervention of reason.

"The following case," he continues, "recorded by Gledditsch, has also every indication of the intervention of reason. One of his friends, wishing to desiccate a Frog, placed it on the top of a stick thrust into the ground, in order to make sure that the Necrophori should not come and carry it off. But this precaution was of no effect; the insects, being unable to reach the Frog, dug under the stick and, having caused it to fall, buried it as well as the body." ("Suites a Buffon. Introduction a l'entomologie" volume 2 pages 460-61.--Author's Note.)

To grant, in the intellect of the insect, a lucid understanding of the relations between cause and effect, between the end and the means, is an affirmation of serious import. I know of scarcely any better adapted to the philosophical brutalities of my time. But are these two little stories really true? Do they involve the consequences deduced from them? Are not those who accept them as reliable testimony a little over-simple?

To be sure, simplicity is needed in entomology. Without a good dose of this quality, a mental defect in the eyes of practical folk, who would busy himself with the lesser creatures? Yes, let us be simple, without being childishly credulous. Before making insects reason, let us reason a little ourselves; let us, above all, consult the experimental test. A fact gathered at hazard, without criticism, cannot establish a law.

I do not propose, O valiant grave-diggers, to belittle your merits; such is far from being my intention. I have that in my notes, on the other hand, which will do you more honour than the case of the gibbet and the Frog; I have gleaned, for your benefit, examples of prowess which will shed a new l.u.s.tre upon your reputation.

No, my intention is not to lessen your renown. However, it is not the business of impartial history to maintain a given thesis; it follows whither the facts lead it. I wish simply to question you upon the power of logic attributed to you. Do you or do you not enjoy gleams of reason? Have you within you the humble germ of human thought? That is the problem before us.

To solve it we will not rely upon the accidents which good fortune may now and again procure for us. We must employ the breeding-cage, which will permit of a.s.siduous visits, continued inquiry and a variety of artifices. But how populate the cage? The land of the olive-tree is not rich in Necrophori. To my knowledge it possesses only a single species, N. vestigator (Hersch.); and even this rival of the grave-diggers of the north is pretty scarce. The discovery of three or four in the course of the spring was as much as my searches yielded in the old days. This time, if I do not resort to the ruses of the trapper, I shall obtain them in no greater numbers; whereas I stand in need of at least a dozen.

These ruses are very simple. To go in search of the layer-out of bodies, who exists only here and there in the country-side, would be almost always waste of time; the favourable month, April, would elapse before my cage was suitably populated. To run after him is to trust too much to accident; so we will make him come to us by scattering in the orchard an abundant collection of dead Moles. To this carrion, ripened by the sun, the insect will not fail to hasten from the various points of the horizon, so accomplished is he in the detection of such a delicacy.

I make an arrangement with a gardener in the neighbourhood, who, two or three times a week, supplements the penury of my acre and a half of stony ground, providing me with vegetables raised in a better soil. I explain to him my urgent need of Moles, an indefinite number of moles.

Battling daily with trap and spade against the importunate excavator who uproots his crops, he is in a better position than any one else to procure for me that which I regard for the moment as more precious than his bunches of asparagus or his white-heart cabbages.

The worthy man at first laughs at my request, being greatly surprised by the importance which I attribute to the abhorrent creature, the Darboun; but at last he consents, not without a suspicion at the back of his mind that I am going to make myself a wonderful flannel-lined waist-coat with the soft, velvety skins of the Moles, something good for pains in the back. Very well. We settle the matter. The essential thing is that the Darbouns shall reach me.

They reach me punctually, by twos, by threes, by fours, packed in a few cabbage-leaves, at the bottom of the gardener's basket. The worthy man who lent himself with such good grace to my strange requirements will never guess how much comparative psychology will owe him! In a few days I was the possessor of thirty Moles, which were scattered here and there, as they reached me, in bare portions of the orchard, amid the rosemary-bushes, the arbutus-trees, and the lavender-beds.

Now it only remained to wait and to examine, several times a day, the under-side of my little corpses, a disgusting task which any one would avoid who had not the sacred fire in his veins. Only little Paul, of all the household, lent me the aid of his nimble hand to seize the fugitives. I have already stated that the entomologist has need of simplicity of mind. In this important business of the Necrophori, my a.s.sistants were a child and an illiterate.

Little Paul's visits alternating with mine, we had not long to wait.

The four winds of heaven bore forth in all directions the odour of the carrion; and the undertakers hurried up, so that the experiments, begun with four subjects, were continued with fourteen, a number not attained during the whole of my previous searches, which were unpremeditated and in which no bait was used as decoy. My trapper's ruse was completely successful.

Before I report the results obtained in the cage, let us for a moment stop to consider the normal conditions of the labours that fall to the lot of the Necrophori. The Beetle does not select his head of game, choosing one in proportion to his strength, as do the predatory Wasps; he accepts it as hazard presents it to him. Among his finds there are little creatures, such as the Shrew-mouse; animals of medium size, such as the Field-mouse; and enormous beasts, such as the Mole, the Sewer-rat and the Snake, any of which exceeds the powers of excavation of a single grave-digger. In the majority of cases transportation is impossible, so disproportioned is the burden to the motive-power. A slight displacement, caused by the effort of the insects' backs, is all that can possibly be effected.

Ammophilus and Cerceris, Sphex and Pompilus excavate their burrows wherever they please; they carry their prey thither on the wing, or, if too heavy, drag it afoot. The Necrophorus knows no such facilities in his task. Incapable of carrying the monstrous corpse, no matter where encountered, he is forced to dig the grave where the body lies.

This obligatory place of sepulture may be in stony soil; it may occupy this or that bare spot, or some other where the gra.s.s, especially the couch-gra.s.s, plunges into the ground its inextricable network of little cords. There is a great probability, too, that a bristle of stunted brambles may support the body at some inches from the soil. Slung by the labourers' spade, which has just broken his back, the Mole falls here, there, anywhere, at random; and where the body falls, no matter what the obstacles--provided they be not insurmountable--there the undertaker must utilize it.

The difficulties of inhumation are capable of such variety as causes us already to foresee that the Necrophorus cannot employ fixed methods in the accomplishment of his labours. Exposed to fortuitous hazards, he must be able to modify his tactics within the limits of his modest perceptions. To saw, to break, to disentangle, to lift, to shake, to displace: these are so many methods of procedure which are indispensable to the grave-digger in a predicament. Deprived of these resources, reduced to uniformity of method, the insect would be incapable of pursuing the calling which has fallen to its lot.

We see at once how imprudent it would be to draw conclusions from an isolated case in which rational coordination or premeditated intention might appear to intervene. Every instinctive action no doubt has its motive; but does the animal in the first place judge whether the action is opportune? Let us begin by a careful consideration of the creature's labours; let us support each piece of evidence by others; and then we shall be able to answer the question.

First of all, a word as to diet. A general scavenger, the Burying-beetle refuses nothing in the way of cadaveric putridity. All is good to his senses, feathered game or furry, provided that the burden do not exceed his strength. He exploits the batrachian or the reptile with no less animation, he accepts without hesitation extraordinary finds, probably unknown to his race, as witness a certain Gold-fish, a red Chinese Carp, whose body, placed in one of my cages, was instantly considered an excellent t.i.t-bit and buried according to the rules. Nor is butcher's meat despised. A mutton-cutlet, a strip of beefsteak, in the right stage of maturity, disappeared beneath the soil, receiving the same attention as those which were lavished on the Mole or the Mouse. In short, the Necrophorus has no exclusive preferences; anything putrid he conveys underground.

The maintenance of his industry, therefore, presents no sort of difficulty. If one kind of game be lacking, some other--the first to hand--will very well replace it. Neither is there much trouble in establishing the site of his industry. A capacious dish-cover of wire gauze is sufficient, resting on an earthen pan filled to the brim with fresh, heaped sand. To obviate criminal attempts on the part of the Cats, whom the game would not fail to tempt, the cage is installed in a closed room with glazed windows, which in winter is the refuge of the plants and in summer an entomological laboratory.

Now to work. The Mole lies in the centre of the enclosure. The soil, easily shifted and h.o.m.ogeneous, realizes the best conditions for comfortable work. Four Necrophori, three males and a female, are there with the body. They remain invisible, hidden beneath the carca.s.s, which from time to time seems to return to life, shaken from end to end by the backs of the workers. An observer not in the secret would be somewhat astonished to see the dead creature move. From time to time, one of the s.e.xtons, almost always a male, emerges and goes the rounds of the animal, which he explores, probing its velvet coat. He hurriedly returns, appears again, once more investigates and creeps back under the corpse.

The tremors become more p.r.o.nounced; the carca.s.s oscillates, while a cushion of sand, pushed outward from below, grows up all about it. The Mole, by reason of his own weight and the efforts of the grave-diggers, who are labouring at their task beneath him, gradually sinks, for lack of support, into the undermined soil.