510 PHYSIOLOGY. 



upon the surface, where exposure is such that the leveling function 

 of the blood is hindered. The mean, daily temperature of a healthy 

 man varies between 98 and 99 F. In the rectum it is 98.96 F.; 

 in the axilla, 98.45 F.; in the mouth, 98.36 F. These figures 

 represent the averages obtained from various observations, but they, 

 too, are subject to various variations from exercise, rapid respiration, 

 food within the alimentary tract, etc. 



From frequent observations and numerous tables it will be 

 found that the mean rectal temperature of other mammals is, for the 

 most part, higher than that of man. In the case with birds, the 

 temperature averages from two to three degrees higher than that of 

 mammals. In securing these observations it is always necessary that 



Fig. 179. Variations in the Bodily Temperature during Health 

 within Twenty- four Hours. (LANDOIS.) 



L according to v. Liebermeister. J according to Jtirgensen. 



the animal should not struggle either before insertion or during the 

 time that the thermometer is in position. A faulty reading of as 

 much as three degrees may occur when the animal struggles or has 

 been previously chased. 



Hibernation. Many animals regularly at the approach of cold 

 weather gradually lose their activities until they apparently have 

 lost all of their functions and are dormant. Such a state is known 

 as hibernation. The temperature of the animal's body is but a trifle 

 above that of the surrounding atmosphere. The respirations are 

 greatly decreased in number, while the rhythm is of the Cheyne- 

 Stokes type. The heart's action in point of force and frequency is 

 much reduced during hibernation. Animals whose hearts during 

 active life beat one hundred or more now register but fourteen or 



