Silk

and Silk-worm, (silk-.) [A. S. seo lc.] (Zool. and Manuf.) Silk is a well-known species of glo y thread, spun by the caterpillar of various species of the gen. Bombyx (see BOMBYCIDAE), of which Bombyz mor i, the Silk-worm, which feeds, as every one knows, on the leaves of the white mulberry, or, when they cannot be obtained, on those of the black mulberry or lettuce. The Silk-worm remains in its larva state about six weeks, changing its skin four times during that period, and, like other caterpillars, abstaining from food for some time before each change. When full grown, it entirely ceases to feed, and begins to form itself a loose envelopment of silken fibres in some convenient spot which it has chosen for that purpose, and afterwards proceeds to enwrap itself in a much closer covering, forming an oval yellow silken case or ball about the size of a pigeon's egg, in which it changes to a chryBalis, and after lying thus enclosed about fifteen days, gives birth to the Moth. This, however, is always carefully prevented when these insects are reared for the purpose of commerce, the Moth greatly injuring the silk of the ball by discharging a quantity of colored fluid before it leaves the cell. The Silk-worm, when first hatched, is black, and does not exceed in length one fourth of an inch. The desire for food is the first symptom it exhibits of life, and at this period it is more active than at any other. When about eight days have elapsed after its hatching, its head becomes considerably enlarged, and it turns sick, refuses food, and remains in a state of lethargy for about three days. This sickne would appear to arise from the pre ure of the animal's skin, which has become too tight for the increased bulk of its body. Indeed, the very great difference in the size of the worm, from the beginning to the end of its caterpillar state, is so great, that nature has furnished it with several skins, each of which it casts in succe ion. Another species of Silk-worm, Bombyx cynthia, which feeds on the Ailanthus glandulosa, has been lately introduced from China into Europe, where it seems to succeed well. In a state of nature everything now remains quiet till the pupa becomes a moth. Where the insect is bred as an article of trade, the ball is taken from the mulberry-tree in the condition at which it is now described to be, and the S., W., having been killed by heat, is unwound. If the animal were left to itself it would force its way through, and spoil the S. As soon as the worms have produced their balls, or cocoons, they become an article of commerce, for in those countries where S. is cultivated,few persons reel off their cocoons, but sell them to others, who make this operation a separate busine . The S., as formed by the worm, is so very fine that, if each ball, or cocoon, were reeled separately, it would be totally unfit for the purpose of the manufacturer; in the reeling, therefore, the ends of several cocoons are joined and reeled together out of warm water, which, softening their natural gum, makes them stick together so as to form one strong thread. The first S. known in Europe appears to have been brought from China; for, though a trade in S. began in a very early age, it was not before A. D. 555 that the arts of raising the worms and working the silk were known to the Western world. When S. was first introduced into Rome it was so costly that it sold for its weight in gold, and was only used by a few ladies of the patrician rank. In the beginning of the reign of Tiberius, a law was pa ed that no man should disgrace himself by the effeminate practice of wearing silken garments; but Helio gab alus broke this law by wearing a dre composed wholly of silk. The example was quickly followed, and from the capital the practice soon extended to the provinces. Greece was distinguished not only for the rearing of the Silk-worm, but for the skill and succe with which the manufacture was carried on by the inhabitants of Thebes, Corinth, . In time it spread to Italy; and in 1480 it was introduced into France, the city of Lyon being still, up to the present time, the great European mart for silk manufacture. The cultivation and production of S. was commenced in the United States at a very early period. but it is only half a century since the first mill in America for making sewing-silks was erected in Mans field, Connecticut, and the first S. made by machinery was also turned there in 1829. There are now many manufactories at Paters on, N. J., at Philadelphia, and in the States of New York, Ma achusetts, Connecticut, . In California, the cultivation of S. began on a large scale in 1869, and promises to be very remunerative. S. changes its name as its manufacture progre es. When wound off the cocoons, it is raw S.; when one of the reeled threads is twisted to give it strength, it is singles; when two or more threads are twisted together, it is tram, and is generally used as the " shoot," or "weft; " when two or more singles are twisted together, in a direction contrary to their own twist, it is thrown S.; the proce is called organ zin ing, the S. thus manufactured organ zine, and it serves for the " web" of the best S. stuffs. The S. which the Silk-worm first forms, by throwing the thread in different directions, and also that from any cause not reeled off, is flo [Fr. filoselle), and is used for carding and spinning. [s. 826] Silk - cotton Tree. (Bot.) The common na Silk - cotton Tree. (Bot.) The common name of the gen. BOMBAX, q. v. [s. 827]