G4 NATURAL HISTORY. 
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itfelf, till it affumes its winged form. This cone or ball is fpun frorii 
two little longifh kinds of bags ‘that lie above the inteftines, and 
are filled with a gummy fluid, of a marigold colour. This is the 
fubRance of which the threads are formed; and the little animal 
is furnifhed with a furprifing apparatus for {pinning it to the degree 0 
finenefs which its occafions may require. This inftrument in fome 
meafure refembles a wire-drawer’s machine, in which gold or filver y 
threads are drawn to any degree of minutenefs; and through this the 
animal draws its thread with great afliduity. As every thread proceeds 
from two gum bags, it is probable that each fupplies its own; which, 
however, are united, as they proceed from the animal’s body. If we 
examine the thread with a microfcope, it will be found thar it is flatted 
on one fide, and groved along its length: from hence we may infer, 
that it is doubled juft upon leaving the body; and that the two threads 
ftick to each other by that gummy quality of which they are poffeffed. 
Previous to fpinning its web, the filkworm feeks out fome convenient 
place to erect its cell, without any obftrudion. When it has found 4 
leaf, or a chink fitted to its purpofe, it begins to wreathe its head in 
every direction, and faftens its thread on every fide to the fides of its 
retreat. ‘Though all its firft effays feem perfectly confufed, yet they 
are not altogether without defign: there appears indeed, no order oF 
contrivance in the difpofal of its firft threads; they are by no means 
laid artfully over each other, but are thrown out at random, to fervée 
as an external fhelrer againft 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. 
Malphigi pretends to have obferved fix different layers in a fingle 
cone of filk: but what eafily may be obferved is, that it is compofed exter 
nally of a kind of rough cotton-like fub&ance, which is called flofs; within 
the thread is more diftiné and even; and next the body of the aurelia, 
the apartment feems lined with a fubftance of the hardnefs of papers 
but of a much ftronger confiftence: It mult not be fuppofed, that the 
thread which goes to compofe the cone, is rolled round, as we roll 4 
bottom; on the contrary, it lies upon it in a very irregular mannet, 
and winds off now from one fide of the cone, and then from the other. 
"This whole thread, if meafared, will be found about three hundred 
yards long; and fo very fine, that eight or ten of them are generally 
volled off into one by the manufacturers. The cone, when completeds 
is in form like a pigeon’s egg, and more pointed at one end. than the 
other; at the fmaller end, the head of the aurelia is generally found + 
and this is the place that the infe€t, when converted into a moth, if 
generally feen to burft through. \ e 
It is generally a fortnight or three weeks before the aurelia is chat 
ed into a moth; but no fooner is the winged infect completely form? 
ed, than having divefted itfelf of its aurelia fkin, it prepares to bur# 
through its cone, or outward prifon: for this purpofe it extends il8 
head towards the point of the cone, butts with its eyes, which at® 
rough, againft the lining of its cell, wears it away, and at laft pufhe® 
forward, through a paflage which is fmall at firft, but which enlarge? 
as the animal increafes its efforts for emancipation ; while the tattere® 
femnants of its aurelia fkin lic in confufion within the cone, like a but 
Th 
dle of dirty linen, : 
