THE FOOD AND DIGESTION 363 



Since heat is constantly being given off, the temperature at 

 the surface of the body is always lower than the temperature 

 in the interior. The temperature of the rectum may be taken 

 as a measure of the internal temperature. 



The mean daily temperature of a healthy man is : 



c. F. 



Kectum . . . 37*2 98-96 



Axilla .... 36-9 9845 



Mouth .... 36-87 98-36 



But the temperature varies throughout the course of life. 



c. 



Infant . . . . 37 '5 

 Under 25 years . . 37*2 

 About 40 . . . 37-1 

 Old Age . . . 37-2 to 37*5 



It also varies throughout the course of the twenty-four 

 hours, and since this is a matter of great importance in 



FIG. 150. Chart of the daily variation of temperature in the normal human subject 

 in degrees Centigrade. (RiCHET. ) 



medicine, it has been very carefully studied by many 

 observers. The difference is not more than 1 C. It is 

 lowest in the early morning and highest in the afternoon. 

 Under all normal conditions the temperature of man 



