ANIMAL HEAT. 255 



tion is much less rapid, and the temperature of their bodies differs 

 but little from that of the air or water which they inhabit. Birds 

 and mammalians are therefore called " warm-blooded," and reptiles 

 and fish " cold-blooded" animals. There is, however, no other dis- 

 tinction between them, in this respect, than one of degree. - In 

 reptiles and fish there is also an internal source of heat ; only this 

 is not so active as in the other classes. Even in these animals a 

 difference is usually found to exist between the temperature of their 

 bodies and that of the surrounding media. John Hunter, Sir 

 Humphrey Davy, Czermak, and others, 1 have found the temperature 

 of Proteus anguinus to be 63.5, when that of the air was 55.4; 

 that of a frog 48 U , in water at 4AA ; that of a serpent 88.46, in 

 air at 81.5 ; that of a tortoise 84, in air at 79.5 ; and that of fish 

 to be from 1.7 to 2.5 above that of the surrounding water. 



The following list 2 shows the mean temperature belonging to 

 animals of different classes and species. 



ANIMAL. MEAN TEMPERATURE. 



f Swallow ...... 1110.25 



Heron ....... llic.2 



B,RDS. ' Raven ....... 108 ' 5 



Pigeon ....... 107.6 



I Fowl ....... 1060.7 



I Gull ....... 1000.0 



quirrel ...... 105O 



k>at . . ..... 1020.5 



at ....... 1010.3 



Dog ....... 990.4 



Man ....... 980.6 



[Ape ....... 950.9 



REPTILE. Toad ....... 51O.6 * 



r Carp ....... 510.25 



\ Tench ....... 520.10 



In the invertebrate animals, as a general rule, the internal heat 

 is produced in too small quantity to be readily estimated. In some 

 of the more active kinds, however, such as insects and arachnida, 

 it is occasionally generated with such activity that it may be 

 appreciated by the thermometer. Thus, the temperature of the 

 butterfly, when in a state of excitement, is from 5 to 9 above 

 that of the air; and that of the humble-bee from 3 to 10 higher 



1 Simon's Chemistry of Man, Philadelphia edition, p. 124. 



2 Ibid., pp. 123126. 



