858 INSECTA—CATERPILLAR 
together; and though they seem dead at the bottom, yet, when taken out 
yecover, and resume their former vivacity. 
If the caterpillar be cut open longitudinally along the. back, its intestines 
will be perceived running directly in a straight line from the mouth to the 
anus. They resemble a number of small bags opening into each other, 
and strengthened on both sides by a fleshy cord, by which they are united. 
These insects are, upon many occasions, seen to cast forth the internal coat 
of their intestines with their food, in the changes which they so frequently 
undergo. But the intestines take up but a small part of the animal’s body, 
if compared to the fatty substance in which they are involved. This sub- 
stance changes its color when the insect’s metamorphosis begins to approach ; 
and from white it is usually seen to become yellow. If to these parts we 
add the caterpillar’s implements for spinning (for all caterpillars spin at one 
time or another,) we shall have a rude sketch of this animal’s conformation. 
The life of a caterpillar seems one continued succession of changes; and 
it is seen to throw off one skin only to assume another; which also is di- 
vested in its turn; and thus for eight or ten times successively. 
How laborious soever this operation may be, it is performed in the space 
of a minute ; and the animal, having thrown off its old skin, seems to enjoy 
new vigor, as well as to have acquired coloring and beauty. Sometimes it 
happens that it takes a new appearance and colors very different from the 
old. Those that are hairy still preserve their covering, although their 
ancient skin seems not to have lost a single hair; every hair appears to have 
been drawn, like a sword from the scabbard. The fact, however, is, that 
a new crop of hair grows between the old skin and the new, and probably 
helps to throw off the external covering. 
The caterpillar having in this manner continued for several days feeding, 
and at intervals casting its skin, begins at last to prepare for its change into 
an aurelia or pupa. 
Preparatory to this important change, the caterpillar most usually quits 
the plant or tree on which it fed; or at least attaches itself to the stalk or 
the stem, more gladly than the leaves. It forsakes its food, and prepares, by 
fasting, to undergo its transmutation. 
Those of them which are capable of spinning themselves a web, set about 
this operation; those which have already spun, await the change in the best 
manner they are able. The web or cone, with which some cover them- 
selves hides the aurelia contained within from the view; but in others, 
where it is more transparent, the caterpillar, when it has done spinning, 
strikes in the claws of the two feet under the tail, and afterwards forces in 
the tail itself by contracting those claws, and violently striking the feet one 
against the other. If, however, they be taken from their web at this time, 
they appear in a state of great languor; and, incapable of walking, remain 
on that spot where they are placed. In this condition they remain one or 
two days, somewhat in the manner they made preparations for changing 
