In the middle of the floss-silk fabric, the silkworm—by a swinging movement of its head—spins the real cocoon. (It is upon this head movement and the resultant stretching principle that the strength of the raw silk depends, and, copying this method of the silkworm, high-tenacity Rayons are produced by a stretching of the fibre.) Over a quarter-of-a-million swinging movements—in the form of a figure “8”—are necessary for the spinning of a cocoon in coils, which coils are firmly fastened together by a gum-fluid, and the cocoon being spun around the body of the silkworm thus provides it with a natural armour during pupation.
Every cocoon consists of one filament of 1,000/3,000 yards length, and as the filament lengthens, the spinning silkworm gradually disappears from view, and the cocoon becomes thicker and thicker (d).
After 3/4 days, the silkworm will have used up all its liquid, and by and by, as the juice diminishes, the filament becomes thinner and thinner until at last the silkworm polishes the inner side of the cocoon, and changing its skin for the last time, becomes the silk-moth pupa.
After 14/20 days, the pupa develops into the moth which softening the cocoon with a brown, gland liquid, in the place where it wishes to emerge, separates the cocoon threads with its forefeet and comes out to the daylight (e). This is the natural method adopted by the moth, but with a view to the prevention of damage to the cocoon, the pupa in the cocoon is killed by artificial means (reference to these means is made later) before reaching the moth stage.
The male moth (h) is smaller, more lively, and has bushy feelers. The female (g) is larger, and has feelers like threads.