In rearing the silk-worm, as soon as the latter is hatched, it is placed on mulberry-leaves, and for five weeks it does nothing but eat, in that time consuming many times its weight of food.[33] Then it begins to spin the material that forms its chrysalis case or cocoon. The outer part of the case consists of a tough envelope not unlike coarse tissue-paper; the inner part is a fine thread about one thousand feet long that has been wound around the body of the worm. This thread or filament is the basis of the silk textile industry.
Copyright, 1898, by Nature Study Pub. Co.
SILK INDUSTRY
1. Silkworm Eggs
2. Fourth-stage Worm
3. Pupa in Cocoon
4. Cocoon
5. Male Moth
6. Female Moth
7. Unspun Silk
8. Raw Manufactured Silk
9. Manufactured Silk
SILK PRODUCING REGIONS
At the proper time the cocoons are gathered and, if immediately to be used, are plunged into hot water. This not only kills the chrysalids but softens the cocoons as well, so that the outer cases may be removed. The cases removed, the rest of the cocoon is soaked in warm water until the gummy matter is softened and the fibres are free enough to be reeled. In the latter process the ends of a number of cocoons, varying from five to twenty, are caught and loosely twisted into a single strand. The silk thus prepared forms the "raw silk" of commerce. Sometimes a number of strands of raw silk are twisted into a coarse thread, thereby forming "thrown silk." For convenience in handling, both raw and thrown silk are made into large skeins called hanks, and most of the silk product is exported in this form.
A given quantity of cocoons yields scarcely more than one-tenth its weight in good raw silk. The remaining part, consisting of broken fibres and cases, is shredded and spun into silk thread of inferior quality. This material, commonly called "husks" or "knubs," forms an important item in silk manufacture, and much of it is exported to Europe and America.
