THE SILKWORM, 
find is thrown aside by the animal’s feet. All these changes 
are made in three weeks or a month’s time; after which it 
begin* to feed once more, still in its caterpillar form, but a 
good deal di tiering from itself belbre its change. In a few 
days’ time it seems to sleep again ; and, when it awakes, it 
again changes its clothing, and continues feeding as before. 
When it has thus taken a sufficiency of food, and its parts 
are disposed for assuming the aurelia form, the animal for- 
sakes, for the last time, all food and society, and prepares 
itself a retreat to defend it from external injuries, while it is 
seemingly deprived of life and motion. 
This retreat is no other than its cone or ball of silk, which 
Nature has taught it to compose with great art ; and within 
which it buries itself, till itassumes its winged form. This 
cone or ball is spun from two little longish kinds of bags that 
lie above the intestines, and are tilled with a gummy fluid, of 
a marigold colour. This is the substanceof which the threads 
are formed ; and the little animal is furnished with a surpris- 
ing apparatus lor spinning it to the degree of lineness which 
its occasions may require. This instrument in some measure 
resembles a wire-drawer’s machine, in which gold or silver 
threads are drawn to any degree of minuteness; and through 
this the animal draws its thread with great assiduity. As 
every thread proceeds from two gum bags, it is probable that 
each supplies its own ; which, however, are united, as they 
proceed from the animal’s body. If we examine the thread 
with a microscope it will be found that it is Hatted on each 
side, and grooved along its length : whence we may infer, that 
it is doubled just upon leaving the body ; and that the two 
threads stick to each other by that gummy quality of which 
they are possessed. Previous to spinning its web, the silk- 
worm seeks out some convenient place to erect its cell, with- 
out obstruction. When it lias found a leaf, on a chink 
fitted to its purpose, it begins to writhe its head in every 
direction, and fastens its thread on every side to the sides of 
its retreat. Though all its first essays seem perfectly con- 
fused, yet they are not altogether without design ; there 
appears indeed no order or contrivance in the disposal of its 
first threads : they are by no means laid artfully over each 
other ; but are thrown out at random, to serve as an external 
shelter against rain ; for nature having appointed the animal 
to work upon trees in the open air, its habits remain, though 
it is brought up in a warm apartment. 
Malpighi pretends to have observed six different layers in 
a single cone of silk: but what may be easily observed is, 
that it is composed externally of a kind of rough cotton-like 
