220 



anus, was found to be 92.5, beyond which it could 

 not be raised in the above heat. An eel, very weak, 

 whose heat was 44, which was nearly that of the 

 atmosphere, was put into water heated to 65, for 

 fifteen minutes j and upon examination, it was of 

 the same degree of heat with the water. The heat 

 of a tench was, in ten minutes, raised from 41 to 

 55 both in the stomach and rectum, by being put 

 into water at 65. He found also, that a living and 

 a dead tench, and a living and a dead eel, put toge- 

 ther into warm water, received heat equally fast : 

 and when they were exposed to cold, both the living 

 and the dead admitted the cold likewise with equal 

 quickness *. Hence, therefore, the animal heat, in 

 all the classes of animals hitherto mentioned, whether 

 they inhabit the air or the water, seems to follow 

 nearly that of the medium in which they are placed ; 

 and their standard temperature cannot, in conse- 

 quence, be restricted to any fixed point, but must be 

 considered always in relation to that of their sur- 

 rounding medium, 



178. Notwithstanding, however, the low degree 

 of heat which these several classes of animals pos- 

 sess, hardly, in some instances, exceeding that of 

 the medium in which they live, yet this small excess 

 is a proof that they possess within themselves a 

 power of producing heat. The loss of heat which 

 insects (173.) suffer under cold, the fall of tempera- 

 ture which many of the vermes class (174.) undergo 

 from the same cause, the melting of snow (175.) by 



* Observations on Anirral (Economy, p. 104, 105. 



