. The culture of the mulberry silkworm. Silkworms. s THE CULTUKE OF THE MULBEKRY SILKWOEM. The head is a small mass covered with a hard scale, and is provided with jaws that move laterally, like the wing's of a folding door. The alimentary canal extends throughout the entire length of the body, and on each side of it is placed a silk gland (tig. 2). These consist of two whitish or amber-colored cords, which after innumerable curves unite in the spinneret in the region of the mouth. There are also two glands, whose excretoiy canal opens in the spinneret, and covers the silk as it comes out with
. The culture of the mulberry silkworm. Silkworms. s THE CULTUKE OF THE MULBEKRY SILKWOEM. The head is a small mass covered with a hard scale, and is provided with jaws that move laterally, like the wing's of a folding door. The alimentary canal extends throughout the entire length of the body, and on each side of it is placed a silk gland (tig. 2). These consist of two whitish or amber-colored cords, which after innumerable curves unite in the spinneret in the region of the mouth. There are also two glands, whose excretoiy canal opens in the spinneret, and covers the silk as it comes out with an impermeable varnish rendering it insoluble in acids and alkalies. This varnish is about a fifth of the weight of the thread. Hatchings usually occur annually in the spring. Simple contact with the air causes the new-born insect immediately to acquire a vol- ume larger than it had in the egg^ and it quickly begins to gnaw the under surface and edges of the mulberry leaf. It eats day and night at all hours, except when asleep, and in about thirty days grows 14,000 times larger than it was at birth. As the silkworm grows larger it becomes paler in color, because its dark chestnut brown hairs are scattered over a larger surface, thus showing more of the true color of the skin. About five days from its birth the vitality- of the larva decreases, and it eats scantily or not at all, and becomes thin and whitish in color. Then it moves around unquietly, and finding a convenient place attaches itself to it, holding on by its false feet. It thus remains motionless, with the front part of its bod}^ raised up, for a period of time varying according to tempera- ture, and takes its first so-called "sleep," or molt, during which time the body undergoes extraordinary modifications. The skin is en- tirely shed, and all the tissues that can not keep up with the rapid growth of the insect are changed. The scale which covers the snout is the first part of the case to fall, and a new
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectsilkworms, bookyear19
