^ Giispard's Memoir on the 



suits. It appears therefore that dunng the complete hibernation 

 of the snail, the circulation is entirely suspended. 



§ 10. Respiration is also found by the experiments of the author, 

 to cease during this period. If the snails remained submersed dur- 

 ing the whole time, they did not perish : and it is proved that they 

 do not respire the air which fills the space between the operculum 

 and the animal, by its being found to possess the usual proportion 

 of oxygen, on being collected and submitted to tests at the latter 

 part of the period of hibernation. 



§ 11, 12. The animal heat, which even in the summer, when 

 respiration and circulation are most lively, does not exceed one 

 degree above the surrounding atmosphere, is not perceptible dur- 

 ing the months of torpidity. The animal becomes frozen when 

 exposed to cold at exactly the same degree as any other gelatinous 

 body, if the shell is not closed by its operculum ; whilst on the 

 other hand those which are perfectly operculated, and slightly co- 

 vered with earth, endure without injury all the rigours of winter. 

 This power of enduring cold however has its limits, and it appears 

 that on being submitted to a temperature of 16° Fahr. they are 

 frozen, and on becoming thawed, although sometimes they shew 

 signs of life, and even walk, they soon re-enter their shells and 

 shortly after die. At a lower degree, approaching Zero of Fahr., 

 they perish at once. 



§ 13. Their power of sustaining a high degree of heat is no less 

 extraordinary. If exposed to 100° F. they indicated a high great 

 of irritability, alternately emerging from their shells, and re- 

 entering them, and on the temperature being raised to 1200, they 

 appeared dead but became resuscitated on its gradual diminution. 

 Even after sustaining a still higher degree of heat they became 

 slightly re-animated, but subsequently perished ; and on being ex- 

 posed to 127° they were found to be irrecoverably destroyed. 

 Similar experiments made by warm water afforded the same results. 

 § 14. Respecting the remaining functions of these animals, se- 

 cretion, nutrition and absorption, the following is the result of the 

 author's observations. On examining the fringe of the mantle, on 

 the resuscitation of the animal in the spring, it is invariably found 

 io the same state of leanness, and of the same greyish colour as 



