Silk owes its position as one of the three leading textiles to its qualities of strength, elasticity and beauty—in which respects it surpasses all other fabrics. Its production dates far into antiquity; for centuries China was the seat of the industry, guarding the secret methods and processes with the utmost care. During the sixth and seventh centuries A. D. the secret began to leak out and sericulture gradually found root in the Near East and the Levant, whence it spread to Greece, Italy, France and Spain. Japan also took it up and developed it to a very high point.
Industry in America
Attempts to establish the industry in America have been generally unsuccessful, high costs precluding the possibility of competing with foreign conditions. In addition, the raising of raw silk has been built up principally in countries where there is a system of home industry—a social and industrial system never developed in the United States. However, although America has never been a factor in the producing of the raw material, it has risen to a place of utmost importance in the manufacture of the finished textile. Immense quantities of raw silk are imported from abroad—principally Japan, Italy, and China—and its conversion into the finished products constitutes a most important part of our industry.
2. The Silk Worm
Names and Types of Silk Worms
The textile fibre known as silk is a filament secreted by one of two general types of moth larvæ—the cultivated and the wild. The largest proportion is, of course, made up of the former, produced by the worm known as the Bombyx mori, while the most common type of wild silk worm is called the Tussah. The name Bombyx mori comes from the name of the family to which the silk worm belongs: the Bombycidoe (spinners), and mori, from the morus multicaulis or mulberry tree, on the leaves of which it feeds. The species Sericaria mori, or silk worm of the mulberry, belongs to the generic class of Lepidoptera or scaly-winged insects.
Bombyx Mori
The Bombyx mori, with which we are chiefly concerned, is divided into other groups according to the cycle of reproduction. The annuals reproduce once a year, and sixty per cent of the silk worms belong to this class. The bivoltines reproduce twice a year, and the polyvoltines, several times during the year, the first crop being the best.
Full Grown Worms