Page:The history of silk, cotton, linen, wool, and other fibrous substances 2.djvu/150

 appearing to find sufficient occupation in forming its silken web, and providing successors for our service, without indulging that grosser appetite which forms the beginning and the end of their desires during their caterpillar existence.

The moth enjoys its liberty for only a very brief space. Its first employment is to seek its mate; after which the female deposits her eggs; and both in the course of two or three days after, end their being.

Formation of Silk. By M. H. Straus, of Durckheim.—"It is generally admitted by naturalists that the thread of the caterpillar is produced by a simple emission of liquid matter through the orifice of the spinner, and that it acquires solidity at once from the drying influence of the air. It was easy to entertain such an hypothesis, for nothing is more simple than the formation of a very fine thread by such a process. But a little reflection will soon show us, even à priori, that it is not possible; for how can we comprehend that so fine a fibre, liquid at the instant of its issue from the aperture, should instantly acquire such a consistence as to bear the weight of the animal suspended by it, and at the same time that it is rapidly produced? Though the fluid, holding the silk in solution, should be quickly volatilised, it must still be a matter of conjecture, how the animal suspended by this thread could be able to arrest its issue, holding on only by the thread itself, for it cannot pinch the thread, seeing that it is only in a liquid state inside, and the thread cannot be glued to the edge of the opening, as its rapid adhesion would prevent its issue while the animal is spinning. A little examination would satisfy us that silk cannot be produced in this manner, but that it is secreted in the form of silk in the silk vessels, and that the spinning apparatus only winds it. The thread is produced in the slender posterior part of the vessel, the inflated portion of which consists of the reservoir of ready formed silk, where it is found in the form of a skein; each thread being rolled up so as to occupy in the silk-worm (Bombex mori) a space of only about a sixth part of the real length of the skein. The fact is shown by the following experiment I made for the purpose of ascertaining whether the silk is formed in the body of the caterpillars.