Réaumur experienced the same disappointment. He tells us how all the eggs sent by his friends proved failures, even when he carried them in a glass tube in his fob to give them a mild temperature. O my revered master, neither the warm shelter of our studies nor the niggardly heating-apparatus of our breeches is enough in this case! What is needed is that supreme stimulant, the kisses of the sun; what is needed, after the morning coolness, which already is sharp enough to make us shiver, is the sudden glow of a glorious autumn day, summer’s last farewell.
It was in such circumstances as these, when a bright sun supplied a violent contrast to a cold night, that I used to find signs of hatching; but I always came too late: the young Cicadæ were gone. At most I sometimes happened to find one hanging by a thread from his native stalk and struggling in mid-air. I thought him caught in some shred of cobweb. [[97]]
At last, on the 27th of October, despairing of success, I gathered the asphodels in the enclosure and, taking the armful of dry stalks on which the Cicada had laid, carried it up to my study. Before abandoning all hope, I proposed once more to examine the cells and their contents. It was a cold morning. The first fire of the season had been lit. I put my little bundle on a chair in front the hearth, without any intention of trying the effect of the hot flames upon the nests. The sticks which I meant to split open one by one were within easier reach of my hand there. That was the only consideration which made me choose that particular spot.
Well, while I was passing my magnifying-glass over a split stem, the hatching which I no longer hoped to see suddenly took place beside me. My bundle became alive; the young larvæ emerged from their cells by the dozen. Their number was so great that my professional instincts were amply satisfied. The eggs were exactly ripe; and the blaze on the hearth, bright and penetrating, produced the same effect as sunlight out of doors. I lost no time in profiting by this unexpected stroke of luck. [[98]]
At the aperture of the egg-chamber, among the torn fibres, a tiny cone-shaped body appears, with two large black eye-spots. To look at, it is absolutely the fore-part of the egg, which, as I have said, resembles the front of a very minute fish. One would think that the egg had changed its position, climbing from the bottom of the basin to the orifice of the little passage. But an egg to move! A germ to start walking! Such a thing was impossible, had never been known; I must be suffering from an illusion. I split open the stalk; and the mystery is revealed. The real eggs, though a little disarranged, have not changed their position. They are empty, reduced to transparent bags, torn considerably at their fore-ends. From them has issued the very singular organism whose salient characteristics I will now set forth.
In its general shape, the configuration of the head and the large black eyes, the creature, even more than the egg, presents the appearance of an extremely small fish. A mock ventral fin accentuates the likeness. This sort of oar comes from the fore-legs, which, cased in a special sheath, lie backwards, stretched against each other in a [[99]]straight line. Its feeble power of movement must help the grub to come out of the egg-shell and—a more difficult matter—out of the fibrous passage. Withdrawing a little way from the body and then returning, this lever provides a purchase for progression by means of the terminal claws, which are already well-developed. The four other legs are still wrapped in the common envelope and are absolutely inert. This applies also to the antennæ, which can hardly be perceived through the lens. Altogether, the organism newly issued from the egg is an exceedingly small, boat-shaped body, with a single oar pointing backwards on the ventral surface and formed of the two fore-legs joined together. The segmentation is very clearly marked, especially on the abdomen. Lastly, the whole thing is quite smooth, with not a hair on it.
What name shall I give to this initial state of the Cicada, a state so strange and unforeseen and hitherto unsuspected? Must I knock Greek words together and fashion some uncouth expression? I shall do nothing of the sort, convinced as I am that barbarous terms are only a cumbrous impediment to science. I shall simply call it “the primary [[100]]larva,” as I did in the case of the Oil-beetles, the Leucospes and the Anthrax.[10]
The form of the primary larva in the Cicadæ is eminently well-suited for the emergence. The passage in which the egg is hatched is very narrow and leaves just room for one to go out. Besides, the eggs are arranged in a row, not end to end, but partly overlapping. The creature coming from the farther ranks has to make its way through the remains of the eggs already hatched in front of it. To the narrowness of the corridor is added the block caused by the empty shells.
In these conditions, the larva in the form which it will have presently, when it has torn its temporary scabbard, would not be able to clear the difficult pass. Irksome antennæ, long legs spreading far from the axis of the body, picks with curved and pointed ends that catch on the road: all these are in the way of a speedy deliverance. The eggs in one cell hatch almost simultaneously. It is necessary that the new-born grubs in front should move out as fast as they can and make [[101]]room for those behind. This necessitates the smooth, boatlike form, devoid of all projections, which makes its way insinuatingly, like a wedge. The primary larva, with its different appendages closely fixed to its body inside a common sheath, with its boat shape and its single oar possessing a certain power of movement, has its part to play: its business is to emerge into daylight through a difficult passage.
Its task is soon done. Here comes one of the emigrants, showing its head with the great eyes and lifting the broken fibres of the aperture. It works its way farther and farther out, with a progressive movement so slow that the lens does not easily perceive it. In half an hour at soonest, the boat-shaped object appears entirely; but it is still caught by its hinder end in the exit-hole.