RISE AND PROGRESS OF ZOOLOGY. Iv 



so cold; but if they are suffered to sleep at 

 some degrees below Zero, they are frozen to 

 death. 



In these facts we find evident proofs of the 

 influence of the external irritants in maintain- 

 ing the activity of the vital system, and we also 

 find evidences equally clear, that life may con- 

 tinue to subsist under the most excessive re- 

 laxation of its movements. 



The peculiar circumstances of organiza- 

 tion which predispose those animals to the 

 lethargic state during winter are as yet very 

 obscure. 



Vipers and rattle-snakes were considered from 

 time immemorial to possess a power of fasci- 

 nating, or attracting within reach, the little 

 animals on which they prey. This Dr. Barton, 

 of Philadelphia, has proved to be a popular 

 error. The rattle snake catches in this manner 

 those little birds, #c, that nestle near the 

 ground, in consequence of their approaching 

 too near in the motions they make to defend 

 their little ones. 



The galvanized electricity emitted by certain 

 fishes constitutes one of the most singular phe- 

 nomena of nature. The wonderful degree to 

 which it exists in the Gymnotus of Guiana has 

 been described by M. de Humboldt; and M. 



