In the next place we shall introduce a subject of great curio-sity, well known by the name of The Silk-worm. - The silk-worm is a species of caterpillar, and, like it, is formed of several moveable rings, and is well furnished with feet and claws, to rest and fix itself where it pleases. It has two rows of teeth, which do not move upwards and downwards, but from right to left, which enables it to press, cut, and tear the leaves in every direction. Along the whole length of its back we perceive through its skin a vessel which performs the functions of a heart. On each side of this insect are nine orifices, which answer to as many lungs, and assist the circulation of the chyle, or nutritive juice. Under the mouth it has a kind of reel with two holes, through which pass two drops of the gum with which its bag is filled; they act like two distaffs, continually furnishing it with the materials of which it makes its silk. The gum which distils through the two holes takes their form, lengthens into a double thread, which suddenly loses the fluidity of the liquid gum, and acquires the consistence necessary to support or to envelope the worm. When that time arrives, it joins the two threads together, by gluing them one over the other with its fore feet. This double thread is not only very fine, but also very strong, and of great length. Each bag has a thread which is nearly five hundred ells long; and as this thread is double, and joined together throughout its length, each bag will be found to contain a thousand ells of silk, though the whole weight does not exceed two grains and a half.

The life of this insect in its vermiform state is very short, and it passes through different states till it gradually arrives at its greatest degree of perfection. When it first emerges from the egg, it is extremely small, perfectly black, and its head of a still brighter black than the rest of its body: in a few days it begins to grow white, or of an ash colour; its coat becomes dirty and ruffled; it casts it off, and appears in a new dress; it becomes larger and much whiter, though a little tinged with green, from feeding upon green leaves. After a few more days (the length of time varying according to the degree of heat and quality of its nourishment) it ceases to eat, and sleeps for about two days; it then agitates and frets itself extremely, becoming red with the efforts it makes: its skin wrinkles and shrivels up, and it throws it off a second time, together with its feet. Within the space of three weeks or a month, we see it fresh dressed three times. It now begins to eat again, and might be taken for a different creature, so much is the appearance of its head, colour, and figure, altered. After continuing to eat for some days, it falls again into a lethargic state; on recovering from which, it once more changes its coat, which makes the third since it issued from its shell. It continues to eat for some time, then, entirely ceasing to take any nutriment, prepares for itself a retreat, and draws out a silken thread, which it wraps round its body in the same manner as we might wind thread round an oval piece of wood. It remains quietly in the bag it has formed, and at the end of fifteen days would pierce it, to issue forth, if it was not killed by being exposed to the heat of the sun, or shut up in an oven. The silk-bags are thrown into hot water, and stirred about with birch twigs to draw out the heads or beginning of the threads, and the silk is afterwards wound upon reels made for the purpose. Thus we are indebted to this little insect for our greatest luxury in clothing: a reflection which ought to humble our pride ; for how can we be vain of the silk which covers us, when we reflect to what we are indebted for it, and how little we are instrumental in the formation of those beauties in our clothing, of which we are vain? Thus we find the most insignificant and despicable objects are the instruments of ornament and advantage to man; an insect that we scarcely condescended to look at, becomes a blessing to thousands of human beings, forms an important article of trade, and is the source of great riches.