The Faber Book of Science (28 page)

But there is a part of the body where no such peril is to be feared – the thorax wounded by the sting. There and there only can the experimenter on a recent victim dig down the point of a needle – nay, pierce through and through without evoking any sign of pain. And there the egg is invariably laid – there the young larva always attacks its prey. Gnawed where pain is no longer felt, the cricket does not stir. Later, when the wound has reached a sensitive spot, it will move of course as much as it can; but then it is too late – its torpor will be too deep, and besides, its enemy will have gained strength. That is why the egg is always laid on the same spot, near the wounds caused by the sting on the thorax, not in the middle, where the skin might be too thick for the new-born grub, but on one side – toward the junction of the feet, where the skin is much thinner. What a judicious choice! what reasoning on the part of the mother when, underground, in
complete darkness, she perceives and utilizes the one suitable spot for her egg!

I have brought up Sphex larvæ by giving them successively crickets taken from cells, and have thus been able, day by day, to follow the rapid progress of my nurslings. The first cricket – that on which the egg is laid – is attacked, as I have already said, toward the point where the dart first struck – between the first and second pairs of legs. At the end of a few days the young larva has hollowed a hole big enough for half its body in the victim’s breast. One may then sometimes see the cricket, bitten to the quick, vainly move its antennæ and abdominal styles, open and close its empty jaws, and even move a foot, but the larva is safe and searches its vitals with impunity. What an awful nightmare for the paralysed cricket! This first ration is consumed in six or seven days; nothing is left but the outer integument, whose every portion remains in place. The larva, whose length is then twelve millimetres, comes out of the body of the cricket through the hole it had made in the thorax. During this operation it moults, and the skin remains caught in the opening. It rests, and then begins on a second ration. Being stronger it has nothing to fear from the feeble movements of the cricket, whose daily increasing torpor has extinguished the last shred of resistance, more than a week having passed since it was wounded; so it is attacked with no precautions, and usually at the stomach, where the juices are richest. Soon comes the turn of the third cricket, then that of the fourth, which is consumed in ten hours. Of these three victims there remains only the horny integument, whose various portions are dismembered one by one and carefully emptied. If a fifth ration be offered, the larva disdains or hardly touches it, not from moderation, but from an imperious necessity.

It should be observed that up to now the larva has ejected no excrement, and that its intestine, in which four crickets have been engulfed, is distended to bursting. Thus, a new ration cannot tempt its gluttony, and henceforward it only thinks about making a silken dwelling. Its repast has lasted from ten to twelve days without a pause. Its length now measures from twenty-five to thirty millimetres, and its greatest width from five to six. Its usual shape, somewhat enlarged behind and narrowed in front, agrees with that general in larvæ of Hymenoptera. It has fourteen segments, including the head, which is very small, with weak mandibles seemingly incapable of the part just played by them. Of these fourteen segments the intermediary ones are
provided with stigmata. Its livery is yellowish-white, with countless chalky white dots.

We saw that the larva began on the stomach of the second cricket, this being the most juicy and fattest part. Like a child who first licks off the jam on his bread, and then bites the slice with contemptuous tooth, it goes straight to what is best, the abdominal intestines, leaving the flesh, which must be extracted from its horny sheath, until it can be digested deliberately. But when first hatched it is not thus dainty: it must take the bread first and the jam later, and it has no choice but to bite its first mouthful from the middle of the victim’s chest, exactly where its mother placed the egg. It is rather tougher, but the spot is a secure one, on account of the deep inertia into which three stabs have thrown the thorax. Elsewhere, there would be, generally, if not always, spasmodic convulsions which would detach the feeble thing and expose it to terrible risks amid a heap of victims whose hind legs, toothed like a saw, might occasionally kick, and whose jaws could still grip. Thus it is motives of security, and not the habits of the grub, which determine the mother where to place its egg.

A suspicion suggests itself to me as to this. The first cricket, the ration on which the egg is laid, exposes the grub to more risks than do the others. First, the larva is still a weakly creature; next, the victim was only recently stung, and therefore in the likeliest state for displaying some remains of life. This first cricket has to be as thoroughly paralysed as possible, and therefore it is stabbed three times. But the others, whose torpor deepens as time passes, – the others which the larvæ only attack when grown strong, – have they to be treated as carefully? Might not a single stab, or two, suffice to bring on a gradual paralysis while the grub devours its first allowance? The poison is too precious to be squandered; it is powder and shot for the Sphex, only to be used economically. At all events, if at one time I have been able to see a victim stabbed thrice, at another I have only seen two wounds given. It is true that the quivering point of the Sphex’s abdomen seemed seeking a favourable spot for a third wound; but if really given, it escaped my observation. I incline to believe that the victim destined to be eaten first always is stabbed three times, but that economy causes the others only to be struck twice.

The last cricket being finished, the larva sets to work to spin a cocoon. In less than forty-eight hours the work is completed, and henceforward the skilful worker may yield within an impenetrable
shelter to the overpowering lethargy which is stealing over it – a state of being which is neither sleeping nor waking, death nor life, whence it will issue transfigured ten months later.

Who does not know the magnificent Moth, the largest in Europe, clad in maroon velvet with a necktie of white fur? The wings, with their sprinkling of grey and brown, crossed by a faint zigzag and edged with smoky white, have in the centre a round patch, a great eye with a black pupil and a variegated iris containing successive black, white,
chestnut
, and purple arcs.

Well, on the morning of the 6th of May [1897], a female emerges from her cocoon in my presence, on the table of my insect laboratory. I forthwith cloister her, still damp with the humours of the hatching, under a wire-gauze bell-jar. For the rest, I cherish no particular plans. I incarcerate her from mere habit, the habit of the observer always on the look-out for what may happen.

It was a lucky thought. At nine o’clock in the evening, just as the household is going to bed, there is a great stir in the room next to mine. Little Paul, half-undressed, is rushing about, jumping and stamping, knocking the chairs over like a mad thing. I hear him call me:

‘Come quick!’ he screams. ‘Come and see these Moths, big as birds! The room is full of them!’

I hurry in. There is enough to justify the child’s enthusiastic and hyperbolical exclamations, an invasion as yet unprecedented in our house, a raid of giant Moths. Four are already caught and lodged in a bird-cage. Others, more numerous, are fluttering on the ceiling.

At this sight, the prisoner of the morning is recalled to my mind.

‘Put on your things, laddie,’ I say to my son. ‘Leave your cage and come with me. We shall see something interesting.’

We run downstairs to go to my study, which occupies the right wing of the house. In the kitchen I find the servant, who is also bewildered by what is happening and stands flicking her apron at great Moths whom she took at first for Bats.

The Great Peacock, it would seem, has taken possession of pretty well every part of the house. What will it be around my prisoner, the cause of this incursion? Luckily, one of the two windows of the study had been left open. The approach is not blocked.

We enter the room, candle in hand. What we see is unforgettable. With a soft flick-flack the great Moths fly around the bell-jar, alight, set off again, come back, fly up to the ceiling and down. They rush at the candle, putting it out with a stroke of their wings; they descend on our shoulders, clinging to our clothes, grazing our faces. The scene suggests a wizard’s cave, with its whirl of Bats. Little Paul holds my hand tighter than usual, to keep up his courage.

How many of them are there? About a score. Add to these the number that have strayed into the kitchen, the nursery, and the other rooms of the house; and the total of those who have arrived from the outside cannot fall far short of forty. As I said, it was a memorable evening, this Great Peacock evening. Coming from every direction and apprised I know not how, here are forty lovers eager to pay their respects to the marriageable bride born that morning amid the mysteries of my study.

My very window-ledge, the confidant of bygone ages, talks to me of a vanished world. It is, literally speaking, an ossuary, each particle of which retains the imprint of past lives. That block of stone has lived. Spines of sea-urchins, teeth and vertebrae of fish, broken pieces of shells, shivers of madrepores form a pulp of dead existences. Examined ashlar by ashlar, my house would resolve itself into a reliquary, a rag-fair of things that were alive in the days of old.

The rocky layer from which building-materials are derived in these parts covers, with its mighty shell, the greater portion of the neighbouring upland. Here the quarry-man has dug for none knows how many centuries, since the time when Agrippa hewed cyclopean flags to form the stages and façade of the Orange theatre. And here, daily, the pick-axe uncovers curious fossils. The most remarkable of these are teeth, wonderfully polished in the heart of their rough veinstone, bright with enamel as though still in a fresh state. Some of them are most formidable, triangular, finely jagged at the edges, almost as large as one’s hand. What an insatiable abyss, a jaw armed with such a set of teeth in manifold rows, placed stepwise almost to the back of the gullet; what mouthfuls, snapped up and lacerated by those serrate shears! You are seized with a shiver merely at the imaginary reconstruction of that awful implement of destruction!

The monster thus equipped as a prince of death belonged to the order of Squalidæ. Paleontology calls him Carcharodon Megalodon. The shark of to-day, the terror of the seas, gives an approximate idea of him, in so far as the dwarf can give an idea of the giant.

Other Squali abound in the same stone, all fierce gullets. It contains Oxyrhinæ (Oxyrhina Xiphodon, Agass.), with teeth shaped like pointed cleavers; Hemipristes (Hemipristis Serra, Agass.), whose mouths bristle with flexuous, steeled daggers, flattened on one side, convex on the other; Notidani (Notidanus Primigenius, Agass.), whose sunk teeth are crowned with radiate indentations.

This dental arsenal tells me how extermination came at all times to lop off the surplus of life; it says:

‘On the very spot where you stand meditating upon a shiver of stone, an arm of the sea once stretched, filled with truculent devourers and peaceable victims. A long gulf occupied the future site of the Rhône Valley. Its billows broke at no great distance from your dwelling.’

Here, in fact, are the cliffs of the bank, in such a state of preservation that, on concentrating my thoughts, I seem to hear the thunder of the waves. Sea-urchins, Lithodomi, Petricolæ, Pholaidids have left their signatures upon the rock: hemispherical recesses large enough to contain one’s fist, round cells, cabins with a narrow conduit-pipe through which the recluse received the incoming water, constantly renewed and laden with nourishment. Sometimes, the erstwhile occupant is there, mineralized, intact to the tiniest details of his striæ and scales, a frail ornament; more often, he has disappeared, dissolved, and his house has filled with a fine sea mud, hardened into a chalky kernel.

In this quiet inlet, some eddy has collected and drowned at the bottom of the mire, now turned into marl, enormous heaps of shells, of every shape and size. It is a molluscs’ burying-ground, with hills for tumuli. I dig up oysters a cubit long and weighing five or six pounds apiece. One could shovel up, in the immense pile, Scallops, Cones, Cytheridæ, Mactridæ, Murices, Turritellidæ, Mitridæ and others too numerous, too innumerable to mention. You stand stupefied before the vital ardour of the days of old, which was able to supply such a pile of relics in a mere nook of earth.

The necropolis of shells tells us, besides, that time, that patient renewer of the order of things, has mown down not only the
individual, a precarious being, but also the species. Nowadays, the neighbouring sea, the Mediterranean, has almost nothing identical with the population of the vanished gulf. To find a few features of similarity between the present and the past, we should have to seek them in the tropical seas. The climate, therefore, has become colder; the sun is slowly becoming extinguished; the species are dying out. Thus speak the numismatics of the stones on my window-ledge.

Without leaving my field of observation, so modest, so limited and yet so rich, let us once more consult the stone and, this time, on the subject of the insect. The country round Apt abounds in a strange rock that breaks off in thin plates, similar to sheets of whitish cardboard. It burns with a sooty flame and a bituminous smell; and it was deposited at the bottom of great lakes haunted by crocodiles and giant tortoises. Those lakes no human eye has ever seen. Their basins have been replaced by the ridges of the hills; their muds, peacefully deposited in thin courses, have become mighty banks of rock.

Let us break off a slab and subdivide it into sheets with the point of a knife, a work as easy as separating the superposed layers of a piece of paste-or mill-board. In so doing, we are examining a volume taken from the library of the mountains, we are turning the pages of a magnificently illustrated book. It is a manuscript of nature, far superior to the Egyptian papyrus. On almost every page are diagrams; nay, better: realities converted into pictures.