THE CATERPILLAR. 



assuming another, seems, in comparison, but 

 a slight operation among these animals: this 

 is but the work of a day ; the other is the 

 great adventure of their lives. Indeed, this 

 faculty of changing the skin, is not peculiar 

 to caterpillars only, but is common to all the 

 insect kind; and even to some animals that 

 claim a higher rank in nature. We have 

 already seen the lobster and the crab out- 

 growing their first shells, and then bursting 

 from their confinement, in order to assume a 

 covering more roomy and convenient. It is 

 probable that the louse, the flea, and the spi- 

 der, change their covering from the same 

 necessity; and growing too large for the crust 

 in which they have been for some time enclos- 

 ed, burst it for another. This period is pro- 

 bably that of their growth ; for as soon as 

 their new skin is hardened round them, the 

 animal's growth is necessarily circumscribed, 

 while it remains within it. With respect to 

 caterpillars, many of them change their skins 

 five or six times in a season ; and this cover- 

 ing, when cast off) often seems so complete, 

 that many might mistake the empty skin for 

 the real insect. Among the hairy caterpil- 

 lars, for instance, the cast skin is covered 

 with hair; the feet, as well gristly as mem- 

 braneous, remain fixed to it; even the parts 

 which nothing but a microscope can discover, 

 are visible in it; in short, all the parts of the 

 head ; not only the skull, but the teeth. 



In proportion as the time approaches in 

 which the caterpillar is to cast its old skin. 

 its colours become more feeble, the skin 

 seems to wither and grow dry. and in some 

 measure resembles a leaf, when it is no lon- 

 ger supplied with moisture from the stock. 

 At that time, the insect begins to find it- 

 self under a necessity of changing; and it is 

 not effected without violent labour, and per- 

 haps pain. A d ly or two before the critical 

 hour approaches, the insect ceases to eat, 

 loses its usual activity, and seems to rest im- 

 moveable. It seeks some place to remain in 

 security ; and no longer timorous, seems re- 

 gardless even of the touch. It is now and 

 then seen to bend itself and elevate its back; 

 again it stretches to its utmost extent: it 

 sometimes lifts up the head, and then lets it 

 fall again; it sometimes wavf>s it three or 

 four times from side to side, and then remains 



no. 67 & 68. 



in quiet. At length, some of the rings of its 

 body, particularly the first and second. ;ire 

 seen to swell considerably, the old skin dis- 

 tends and bursts, till, by repeated swellings 

 and contractions in every ring, the animal 

 disengages itself and creeps from its incon- 

 venient covering. 



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 vigour, as well as ac- 

 quired colouring and beauty. Sometimes it 

 happens that it takes a new appearance, and 

 colours 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. 

 However, the fact 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 con- 

 tinued for several days feeding, and at inter- 

 vals casting its skin, begins at last to prepare 

 for its change into an anrelia. It is most 

 probable that, from the beginning, all the 

 parts of the butterfly lay hid in this insect, 

 in its reptile state; but it required time to 

 bring them to perfection ; and a large quan- 

 tity of food, to enable the animal to undergo 

 all the changes requisite for throwing ofTthese 

 skins, which seemed to clog the butterfly 

 form. However, when the caterpillar has 

 fed sufficiently, and the parts of the future 

 butterfly have formed themselves beneath its 

 skin, it is then time for it to make its first 

 great and principal change into an aurelia, 

 or a chrysalis, as some have chosen to call it; 

 during which, as was observed, it seems to 

 remain for several days, or even months, 

 without life or motion. 



Preparatory to this important change, the 

 caterpillar most usually quits the plant, or 

 the 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 fastiug, to undergo its transmu- 

 tation. In this period, all the food it has 

 taken is thoroughly digested ; and it often 

 voids even the internal membrane which lined 

 its intestines. 



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