EXPERIMENTS OF INSECTS. 313 



the envelope, taking care to leave the respiratory 

 spiracles unobstructed. But it is most obvious, that 

 the 'greater part of all the evaporation which occurs 

 must be through the spiracles, in the same way as a 

 large proportion of the moisture of the human body 

 passes off by the breath. The result, however, of 

 Reaumur's experiments with the varnished chrysalides 

 was, that they were developed several weeks later 

 than wlien placed in their natural circumstances, — 

 which proves, we think, that the envelope has consi- 

 derable influence on the transformatory process going 

 on in the interior, even were we to leave the trans- 

 piration of moisture out of the question.* 



We may remark, that the resuUs of these experi- 

 ^ments afford interesting illustrations of the torpidity 

 of both the larger animals and of plants. In ihe 

 United States of America, for example, many species 

 of animals which become torpid in Pennsylvania, and 

 other more northern parts of the country, remain 

 lively in the Carolinas, and other southern parts of 

 the continent.! Mr. Gough found that the dormouse 

 may be prevented from becoming torpid by supplying 

 it plentifully with food ; and Dr. Reeve, of Norwich, 

 observed the same circumstance in a hedge-hog, 

 which being kept warm and well fed, showed no dis- 

 position to become torpid even during severe weather. | 

 Pallas had a tame marmot, also, which, having be- 

 come very fat during the summer, showed no dispo- 

 sition to torpidity, though exposed to a temperature 

 which threw the whose species into a torpid state in 

 that part of Siberia, In the vegetable kingdom, 

 again, it is a very common phenomenon to see plants 

 revive after exposure to severe frost. Mr. Gough 



* Reaumur, Mem. vol. ii. p. 56. 



•V Barton, in Amer. Phil. Trans, vol. iv. 



I Reeve on Torpidity, p. 73. 



T 



