64 HISTORY OF 



prison. 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 re- 

 tarded or quickened, without doing it the smallest 

 injury. For this purpose, it is only requisite to 

 continue the insect in its aurelia state, by pre- 

 venting the evaporation of its humidity ; which 

 will consequently add some days, nay weeks, to 

 its life: on the other hand, by evaporating its 

 moisture in a warm situation, the animal assumes 

 its winged state before its usual time, and goes 

 through the offices assigned its existence. To 

 prove this, M. Reaumur enclosed the aurelia in 

 a glass tube, and found the evaporated water 

 which exhaled from the body of the insect, col- 

 lected in drops at the bottom of the tube ; he 

 covered the aurelia with varnish, and this mak- 

 ing the evaporation 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 animal in a warm 

 room, he hastened the disclosure of the butter- 

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

 same manner, he delayed it. Warmth acted, in 

 this case, in a double capacity, invigorating the 

 animal, and evaporating the moisture. 



The aurelia, though it bears a different exter^ 

 nal appearance, nevertheless contains within it 

 all the parts of the butterfly in perfect forma- 

 tion, and lying each in a very orderly manner, 

 though in the smallest compass. These, how- 

 ever, are so fast and tender, that it is impossible 

 to visit without discomposing them. When either 



