OF PAPILIONACEOUS INSECTS. 51 



we should have naturally concluded that all others 

 required the same. A slight knowledge of the 

 physiology of minute animals, instructs how many 

 kinds produce at a much lower temperature. The 

 eggs of butterflies and many other insects hatch at a 

 temperature so low as forty-five degrees. If these 

 eggs emerge at fifty-nine degrees lower than is 

 required for the development of birds, what difficulty 

 can we have in believing that at thirteen degrees less 

 than the freezing pqint, other animals are capable of 

 being hatched ? Nor should I be surprised at being 

 told, that there are animals whose eggs would hatch 

 in a much greater degree of cold, after being aware 

 that there are plants, which are beings so similar to 

 animals, that flourish amidst the regions of winter, 

 and even fructify. " 



From the experiments of John Hunter, we find that 

 a hen's egg will freeze by a great degree of coldj 

 while, at the same time, it is possessed of a principle 

 of vitality which prevents its destruction ; but, if 

 once that principle is destroyed, cold operates on it 

 more easily. He mentions that an egg was frozen 

 by the cold of zero. After it was thawed, and again 

 exposed to the same depth of cold, it froze seven 

 minutes and a half sooner. A new laid egg took an 

 hour to freeze in fifteen and seventeen degrees ; but 

 when again exposed, it froze in twenty-five degrees, 

 in half that time.* 



With all these facts before us, we are warranted in 

 coming to the conclusion that cold does not destroy 



* See HUNTER on the Animal JSconomy. 



