HARE KIND. 159 



the congelation of their blood, which is naturally 

 much colder than that of all other quadrupeds. 

 The usual heat of man, and other animals, is 

 about thirty degrees above congelation ; the heat 

 of these is not above ten degrees. Their inter- 

 nal heat is seldom greater than that of the tem- 

 perature of the air. This has been often tried by 

 plunging the ball of the thermometer into the 

 body of a living dormouse, and it never rose be- 

 yond its usual pitch in air, and sometimes it sunk 

 above a degree. It is not surprising, therefore, 

 that these animals, whose blood is so cold natu- 

 rally, should become torpid when the external 

 cold is too powerful for the small quantity of 

 heat in their bodies yet remaining ; and this al- 

 ways happens when the thermometer is not more 

 than ten degrees above congelation. This cold- 

 ness M. Buffon has experienced in the blood of 

 the bat, the dormouse, and the hedgehog, and 

 with great justice he extends the analogy to the 

 marmot, which like the rest is seen to sleep all 

 the winter. This torpid state continues as long 

 as the cause which produces it continues ; and it 

 is very probable that it might be lengthened out 

 beyond its usual term, by artificially prolonging 

 the cold : if, for instance, the animal were rolled 

 up in wool, and placed in a cold cellar, nearly 

 approaching to, but not quite so cold as an ice- 

 house, for that would kill them outright, it would 

 remain perhaps a whole year in its state of insen- 

 sibility. However this be, if the heat of the air 

 be above ten degrees, these animals are seen to 

 revive ; and if it be continued in that degree of 



