KLEIBEB 



o o 



it. When the air temperature rises from 30 C to 40 C, the man 



and cow maintain an almost constant difference between skin and 

 body temperature. This is mainly the result of evaporative cooling. 

 The rabbit, however, lets his skin temperature almost reach the 

 level of the rectal temperature. Rabbits presumably rely mainly on 

 the evaporative cooling in the respiratory system (or possibly the 

 ear surfaces). 



Richet (1889) shaved a rabbit and observed that in this condition 

 the rabbit regulated its body temperature at a lower level. This 

 effect is shown in Figure 4, drawn from data in Richet' s book on 

 animal heat. 



Diurnal Changes of Body Temperature 



Man changes his body temperature during a day in a cyclic 

 fashion, and Kleitman (1951) suggests that differences in this cycle 

 account for differences in the behavior of two types of people, the 

 early risers and the late risers. The late risers are grouchy be- 

 cause their body temperatures are low. They need to be warmed 

 up by a cup of hot coffee to reach a friendly disposition and a posi- 

 tive outlook on life, (See also Kleitman, et al, 1935). 



Some domestic animals, such as the donkey and the camel, 

 start their days with a considerably lower body temperature than 

 that of man, and they do not have the benefit of a cup of coffee. 

 They may possibly be endowed with a higher basic level of social 

 grace than man and donotexpress their grouchy feelings as strong- 

 ly as some human beings do. 



Figure 5 shows the diurnal temperature change of a Holstein 

 cow subjected to an environment simulating the Imperial VaUey 

 (Kibler and Brody, 1956). In man, a temperature of 108 F (42 C) 

 would be regarded as a very high fever and the cow's thermostatic 

 capability seems therefore not very impressive; yet comparison of 

 the cow's daily temperature fluctuations with those of the air tem- 

 perature under actual conditions in the Imperial Valley shows that 

 temperature changes in the body are a small part of those in the 



248 



