THE CATERPILLAR. 



789 



make choice of some tender leaf, which they 

 render still more pliant by diffusing a kind of 

 glue upon it : the leaf thus gradually curls up, 

 and withering us it infolds, the insect wraps 

 itself within, as in a mantle, till the genial 

 warmth of the sun enables it to struggle for 

 new life, and burst from its confinement. 

 Others, whose time of transformation is also 

 near at hand, fasu n their tails to a tree, or to 

 the first worm-hole they meet in a beam, and 

 wait in that defenceless situation. Such 

 caterpillars, on the other hand, as are seen to 

 lie several months in their aurelia state, act 

 with much greater circumspection. Most of 

 them mix their web with sand, and thus make 

 themselves a strong covering : others build in 

 wood, which serves them in the nature of a 

 coffin. Such as have made the leaves of wil- 

 lows their favourite food, break the tender 

 twigs of them first into small pieces, then 

 pound them as it were to powder ; and, by 

 means of their glutinous silk, make a kind of 

 paste, in which they wrap themselves up. 

 Many are the forms which these animals as- 

 sume in (his helpless state ; and it often hap- 

 pens, that the most deformed butterflies issue 

 from the most beautiful aurelias. 



In general, however, the aurelia takes the 

 rude outline of the parts of the animal which 

 is contained within it ; but as to the various 

 colours which it is seen to assume, they are 

 rather the effect of accident ; for the same 

 species of insect docs not at all times assume 

 the same hue, when it becomes an aurelia. 

 In some, the beautiful gold colour is at one 

 time found ; in others, it is wauling. This 

 brilliant hue, which does not fall short of the 

 b ^t gililing, is formed in the same manner in 

 which we see leather obtain a gold colour, 

 though none of that metal ever enters into the 

 tincture. It is only formed by a beautiful 

 brown varnish, laid upon a white ground ; 

 and the white thus gleaming through the 

 transparency of the brown, gives a charming 

 golden yellow. These two colours are found, 

 one over the other, in the aurelia of the little 

 aniual we are describing; and the whole ap- 

 pears gil.led, without any real gilding. 



The aurelia thus formed, and left to time to 

 expand into a butterfly, in some measure re- 

 sembles an animal in an egg, that is to wait 

 for external warmth to hatch it into life and 

 vigour. As the quantity of moisture, that is 



enclosed within the covering of the aurelia, 

 continues to keep its body in the most tender 

 state, so it is. requisite that this humidity 

 should be dried away, before the little butter- 

 fly can burst its pris.on. Many have been the 

 experiments to prove that nature may in this 

 respect be assisted by art ; and that the life of 

 the insect may be retarded or quickened, with- 

 out doing it the smallest injury. For this 

 purpose, it is only requisite to continue the in- 

 sect in its aurelia state, by preventing the 

 evaporation of its humidity; which will con- 

 sequently add some days, nay weeks, to its 

 life : on the other hand, by evaporating its 

 moisture in a warm situation, the animal as- 

 sumes its winged s'ate before its usual time, 

 and goes through the offices assigned its ex- 

 istence. To prove this, Mr. Reaumur enclosed 

 the aurelia in a glass tube ; and found the 

 evaporated water, which exhaled from the 

 body of the insect, collected in drops at the 

 bottom of the tube : he covered the aurelia 

 with varnish ; and this making the evapora- 

 tion more difficult and slow, the butterfly was 

 two months longer than its natural term, in 

 coming out of its case : he found, on the other 

 hand, that by laying the anittial in a warm 

 room, he hastened the disclosure of the butter- 

 fly, and by keeping it in an ice-house, in the 

 same manner h-e delayed it. Warmth acted, 

 in this case, in a double capacity ; invigo- 

 rating the animal, and evaporating the mois- 

 ture. 



The aurelia, though it bears a different ex- 

 ternal appearance, nevertheless contains within 

 it all the parts of the butterfly in perfect for- 

 mation ; and lying each in a very orderly 

 manner, though in the smallest compass. These, 

 however, are so fast and tender,, that it is im- 

 possible to visit without discomposing them. 

 When either by warmth, or increasing vigour, 

 the parts have acquired the necessary force 

 and solidity, the butterfly then seeks to disem- 

 barrass itself of those bands whi< h kept it so 

 long in confinement. Some insects continue 

 under the form of an aurelia not above ten 

 days ; some twenty ; some several months ; 

 and even for a year together. 



The butterfly, however, does not continue 

 so long under the form of an aurelia, as one 

 would be apt to imagine. In general those 

 c -terpillars that provide themselves with cones, 

 continue within them but a few days after the 



