74 



VERTEBRATE RESPIRATION 



10 20 30 AO°C 



External temp. 



Fig. 21. 



The body temperature of a reptile and some mammals at different 

 environmental temperatures (after Martin, C. J. : Phil. Trans. Roy 

 Soc. Lond. Vol 195, 1902.) 



The relationship between external temperature and body 

 temperature of different types of mammal is shown in fig. 21. It 

 is apparent that a eutherian mammal, like a cat, is able to main- 

 tain its temperature near 37° C. for a considerable lowering of 

 environmental temperature. In the monotreme, Echidna, 

 regulation is not so good and the body temperature falls some 

 five degrees when that of the environment is lowered from 

 35° to 5° C. Monotremes, some marsupials, and forms like 

 the Sloth and Anteater amongst the eutherian mammals 

 tend to have relatively low body temperatures (27°-32° C). 

 In these and others, sometimes called heterotherms, the range 

 of body temperature compatible with normal activity may 

 be quite large, e.g., hedgehog, 31-r-36-7° C; dormouse, 

 3r-38° C; opossum, 29-3°-37'8° C. In marsupials, the 



