288 FUNCTIONS AND INSTINCTS. 



cells filled with air between it and the oper- 

 culum. 



The membranous partitions are more nume- 

 rous at the end than at the beginning of winter, 

 and, in snails inhabiting the mountains, than in 

 those on the plains. These animals hybernate 

 at the proper period, at very different tempera- 

 tures, varying from 37 to 77 Fahrenh. Respira- 

 tion ceases during the period of hybernation. 



The mode in which these animals escape 

 from their winter confinement is singular : the 

 air they had expired on retiring into their shell 

 further and further, remains between the dif- 

 ferent partitions of mucous membrane above 

 mentioned, which forms so many cells hermeti- 

 cally sealed ; this they again inspire, and thus 

 acquiring fresh vigour, each separate partition, 

 as they proceed, is broken by the pressure of 

 the foot, projected in part through the mantle; 

 when arrived at the operculum they burst it by 

 a strong effort, and finally detaching it, then 

 emerge, begin to walk and to break their long 

 fast. 1 



In all these proceedings the superintending 

 care and wise provisions of a Father Being are 

 evident. This creature can neither foresee the 

 degree of cold to which it may be exposed in its 

 state of hybernation, nor know by what means it 

 may secure itself from the fatal effects it would 



1 Gaspard and Bell, Zool. Jour. i. 93. ii. 174. 



