"The silkworm is the caterpillar of the mulberry-tree moth (_Bombyx mori_) belonging to the tribe of mealy-winged nocturnal insects, of which in the summer evenings we see so many examples. The eggs of this moth are smaller than grains of mustard-seed, very numerous, slightly flattened, yellowish at first, but changing in a few days to a slate colour. In temperate climates they can be preserved through the winter without hatching until the time when the mulberry tree puts forth its leaves in the following spring. This tree forms the entire food of the caterpillar, and seems almost exclusively its own; for while other trees and vegetables nourish myriads of insects, the mulberry tree is seldom attacked by any but this insect, which in many parts of its native country, China, inhabits the leaves in the open air, and goes through all its changes without any attention from man. The common mulberry (_Morus nigra_), so well known in Great Britain, is not the best species for the nourishment of the silkworm. The white-fruited mulberry (_M. alba_), a native of China, is the best, and is greatly preferred by the insect."[9] The silkworm when first hatched is about a quarter of an inch long. After eight days' feeding, it prepares to change its skin. It throws out filaments of silk, attaching its skin to adjacent objects, becomes sluggish, raises the forepart of its body, and finally the whole outer case is cast off, including the feet and jaws. The newly moulted worm is pale in colour, but speedily regains its appetite, which had failed previous to the change, and it swells so fast that in five days another uncasing becomes necessary. Four of these moults and renewals of the skin bring the caterpillar to its full size, when its appetite becomes voracious, and the succulent parts of the mulberry leaf disappear with extraordinary rapidity. The insect is now nearly three inches long. Beneath the jaw are two small orifices through which the worm draws the silken lines out of its body.