All this seems clear, does it not? The ancient mystery has perished? Man has discovered, in its fulness, the secret of things?
Réaumur does not think so; Réaumur himself, who has guided us so far. In recording his observations he does not appear satisfied, and confesses "that they still leave very much to be desired."[I]
[I] Réaumur, "Histoire des Insectes," tome i., p. 351.
In truth, it is a thing to confound and almost to terrify the imagination, to think that a grub, at the outset no bigger than a thread, should include in itself all the elements of its moultings and metamorphoses; should contain its triple, and even octuple envelopes; nay more, the sheath or case of its nympha and its complete butterfly, all folded up one in another, with an immense apparatus of vessels, respiratory and digestive, of nerves for feeling and muscles for moving! A prodigious system of anatomy! first traced out in complete detail in Lyonnet's colossal work on the willow-grub. The twofold monster, endowed with a strong grub-stomach for the destruction of innumerable hard leaves, will possess ere long a light and delicate apparatus for extracting the honey of flowers. And yet the clothed creature, which contains in its organism a complete silk-manufactory, will almost immediately sweep away the complex system.
One knows the gentle manœuvres by which nature conducts the young of the higher animals from the embryonic existence to the independent life, adapting the old organs to new functions. Here, this is not done. It is not a simple change of condition. The destination is not merely different, but contrary, with a violent contrast. Therefore, instruments fitted for an entirely novel existence are required, and the abolition and definitive sacrifice of the primitive organism.
The revolution, which for all other beings is so well concealed, is here entirely thrown open. And we are enabled to scrutinize with our eyes this astonishing tour de force in numerous grubs which undergo the great change in the light of day, suspended to the branch of a tree by a silken cable.
The effort is worthy of our admiration and pity. To see yonder nymph, short and feeble, soft and gelatinous, without arms or paws, contriving, by the skill with which it expands and contracts its rings, to escape from the heavy and rough machine which it was at first, flinging aside its limbs, setting free its head, and—one hardly dares to record the fact—throwing off its body, and rejecting many of its principal internal organs!
This little body, when it has thus escaped from its long heavy mask (living, nevertheless, but a moment since, a life full of energy), will dangle, and grow dry, and skilfully ascend to its silken fastening. There it prepares to fix itself in its new "Me" as a nymph, while its former "Me," tossed about by the wind, is speedily driven I know not whither.