After having thus provided a support and outlined the cocoon, the worm begins the serious work of constrution.  The filament from its silk receiver issues from two small spinnarets situated near its jaws.  Each filament, as it comes out, is coated with a layer of exceedingly tenacious natural gum, and they at once unite to form a single flattened thread, the two parts lying side by side.  It is this flat thread, called the “baye” or “brin,” which serves as the material for making the cocoon, and which, when subsequently unwound, is the filament used in making up the raw silk.  While spinning, the worm moves its head continually from right to left, laying on the filament in a succession of lines somewhat resembling the shape of the figure eight.  As the worm continues the work of making its cocoon, the filament expressed from its body in the manner described is deposited in nearly even layers all over the interior of the wall of the cocoon, which gradually becomes thicker and harder.  The filament issuing from the spinnarets is immediately attached to that already in place by means of the gum which has been mentioned.  When the store of silk in the body of the worm is exhausted, the cocoon is finished, and the worm, once more shedding its skin, becomes dormant and begins to undergo its change into a moth.  It is at this point that its labors in the production of silk terminate and those of man begin.  A certain number of the cocoons are set aside for reproduction.

In southern countries the reproduction of silkworms is a vast industry to which great attention is given, and which receives important and regular aid from the government.  It is, however, quite distinct from the manufacturing industry with which at present we have to do.  The cocoons to be used for reeling, i.e., all but those which are reserved for reproduction, are in the first place “stifled,” that is to say, they are put into a steam or other oven and the insect is killed.  The cocoons are then ready for reeling, but those not to be used at once are allowed to dry.  In this process, which is carried on for about two months, they lose about two-thirds of their weight, representing the water in the fresh chrysalis.  The standard and dried cocoons form the raw material of the reeling mills, or filatures, as they are called on the Continent.  Each filature endeavors as far as possible to collect, stifle, and dry the cocoons in its own neighborhood; but dried cocoons, nevertheless, give rise to an important commerce, having its center at Marseilles.  The appearance of the cocoon is probably well known to most of our readers.  Industrially considered, the cocoon may be divided into three parts:  (1) The floss, which consists of the remains of the filaments used for supporting the cocoon on the twigs of the brush among which it was built and the outside layer of the cocoon, together with such ends and parts of the thread forming the main part of the shell as have become broken in detaching and handling the cocoon; (2) the shell of the cocoon, which is formed, as has been described, of a long continuous filament, which it is the object of the reeler to unwind and to form up into threads of raw silk; and (3) the dried body of the chrysalis.