THE TEMPERATURE OF THE HUMAN BODY 399 



33-35 C.; the naked skin in a bath of 5 C. still has a temperature of 

 17, and in a bath of 18 and 25 has a temperature of 22 and 26.5 re- 

 spectively. The temperature 2 mm. below the surface i. e., in the subcu- 

 taneous tissues under the same circumstances is 24, 24.8, and 27.5 re- 

 spectively, and in the muscles 12 mm. below the surface is 36.3, 35.9, and 

 36.9 C. (Lefevre). The organs in the upper part of the abdominal cavity 

 are still warmer than the muscles and the rectum. According to Quincke, 

 the temperature in the interior of the stomach (man) is 0.12 C. higher 

 than the rectal temperature, and according to Ito, that of the duodenum 

 (rabbit) is 0.7 C. higher. These higher temperatures may be due, in part 



6P.M. 8 10 12 2A.M. 4 G 10 12 2 p. M. 4 



FIG. 147. The normal diurnal variation of temperature in man, after Jiirgensen. 



at least, to the proximity of the liver, for, according to Lefevre, the tem- 

 perature of the liver (of the dog) may be more than 1 C. higher than the 

 rectal temperature. 



Numerous determinations" of the normal body temperature of man have 

 shown that it presents individual variations of some tenths of a degree. As 

 a mean value 37.5 C. is given as the temperature in the rectum, 37.2 C. 

 in the mouth, and 37 C. in the axilla. Moreover it is not entirely correct 

 to say that man has a constant temperature. Even if we neglect the varia- 

 tions due to diseases or the diminutions due to excessive cooling of the body, 

 it has been shown that the temperature of man in the course of a day under- 

 goes certain normal variations. The difference between minimum and maxi- 

 mum in a thoroughly healthy individual may amount to 1-1.5 or more. 

 These variations run a very regular course which, according to Jiirgensen, 

 shows a minimum early in the morning from three to six o'clock, increases 

 gradually from that time, and after some fluctuations, reaches a maximum 

 about six to seven o'clock in the evening (Fig. 147). 



The cause of these variations is primarily the variations in the intensity 

 of metabolism. If the C0 2 elimination, which to a certain extent may be 

 looked upon as an expression of the relative amount of metabolism, be deter- 

 mined at different times of the day, a surprising agreement is found between 

 its course and that of the body temperature (cf. Fig. 148). It should be 

 noticed that the temperature curve in the figure was not taken from the same 



