Page:Popular Science Monthly Volume 3.djvu/680

662 born infant; the caterpillar, when perfectly developed, is 72,000 times heavier than when it first came from the egg.

In every thing that relates to the body, there is between men and animals more resemblance than is ordinarily believed. We also come from an egg which essentially resembles all others. That this egg may become a man, it must undergo very great changes, many metamorphoses. But all these changes, all these metamorphoses occur in the bosom of the mother, as they are accomplished within the shell for the chicken. For insects in general, and consequently for the silk-worm, a part of these metamorphoses occur in the open day. Hence they have drawn the attention, excited the curiosity, and provoked for a long time the study of naturalists. Let us say a few words about them.

Scarcely is the caterpillar born than it begins to eat. It has no time to lose in gaining a volume 72,000 times greater than it had at first; so it acquits itself conscientiously of its task, and does nothing but eat, digest, and sleep. At the end of some days this devouring appetite ceases; the little worm becomes almost motionless, hangs itself by the hind-feet, raising and holding a little inclined the anterior of its body.

This repose lasts 24, 36, and even 48 hours, according to the temperature; then the dried-up skin splits open behind the head, and soon along the length of the body. The caterpillar comes out with a new skin, which is formed during this species of sleep.

This singular crisis, during which the animal changes his skin as we change our shirt, is called moultmg, when it is a question of caterpillars in general. For the silk-worm, we designate it under the name of sickness. It is, in fact, for the silk-worm, a grave period, during which it often succumbs, if its health is not perfect.

The silk-worms change their skin four times. After the fourth moulting comes a redoubled appetite, which permits them to attain their full size in a few days. Then other phenomena appear. The caterpillar ceases to eat, and empties itself entirely; it seems uneasy, wanders here and there, and seeks to climb. Warned by these symptoms, the breeder constructs for it with branches a cradle or bower, into which it mounts. It chooses a convenient place, hangs itself by the hind feet, and soon, through the spinner of which I have spoken (Fig. 2),