230 



CHAP. XIII. 



ANIMAL HEAT. 



"MAN, other mammalia, and birds, are distinguished from the 

 rest of animals by the natural temperature a of their bodies 

 greatly exceeding that of the medium in which they are accus- 

 tomed to exist. Man is again distinguished from these classes 

 of animals by possessing a much lower temperature than they ; 

 so that in this climate it is about 96 of Fahr., while in them, and 

 especially in birds, it is considerably higher." b 



But all animals, as far as can be ascertained, and even vege- 

 tables, have a tendency to preserve a temperature more or less 

 distinct from that of the surrounding medium ; yet the difference 

 among them in this respect is so great, that they have been di- 

 vided into warm and cold-blooded. To the former belong the 

 more complicated, those whose pulmonary apparatus is most ela- 

 borate, man and mammiferous quadrupeds and birds: to the 

 second, oviparous quadrupeds, fish, and most of the invertebrate. 

 Birds have the highest temperature, 107 to 110; mammiferous 

 quadrupeds, 100 to 101; man, 96 to 98J. There is some va- 

 riety, not only in individuals, but according to age, season, and 

 climate. It is less in the young, according to Dr. Edwards and 

 Despretz c : the former states the human temperature in infancy 

 to be 94? ; the latter asserts, that, while in birds it is 105 in 

 winter, it is nearly 111 in summer, gradually increasing in spring 

 and decreasing in autumn. In the high temperature to which we 



a " W. B. Johnson, History of Animal Chemistry, vol. iii. p. 79." 

 b " The torpid state of some animals, during winter, is of course an exception 

 to this. During it most of the functions cease or languish considerably, and the 

 animal heat is reduced nearly to coolness. This well-known circumstance pre- 

 vents me from acceding to the opinion of the very acute J. Hunter, that the 

 animals which we call warm-blooded should rather be called animals of a per- 

 manent heat under all temperatures. On the Blood, p. 15." 



c De V Influence des Agens Physiques. Edinburgh Journal of Science, vol. iv. 

 p. 1 85. J. Hunter states that the temperature of the ass is one degree higher in 

 the evening than the morning. - On the Blood, p 298. 



