ANIMAL HEAT 523 



Natural Surfaces (continued). 



On hair (boy) 30' 



Under hair over sagittal suture (boy) - 337-34* 



Shaved skin of neck (rabbit) - - 36-5 " 



On hair 31-5 



between eyes - - - 307 



Artificial Surfaces. 



Room (Surface of trousers over thigh 237-287 

 temperature,! coat over arm - - - 26-8 

 ^ 7 . 5 o ' [ waistcoat - - - -26* 



Normal Variations in the Temperature. The internal tem- 

 perature, as has been already said, is not strictly constant. 

 It varies with the time 

 of day ; with the taking 

 of food ; with age ; to 

 some extent with violent 

 changes in the external 

 temperature, such as 

 those produced by hot 

 or cold baths ; and pos- 

 sibly with sex. 



The daily curve of 

 temperature shows a 

 minimum in the early 

 morning, between two FIG. 143. CURVE SHOWING THE DAILY 

 and six o'clock (36-3 C.), VARIATION OF BODY TEMPERATURE. 



and a maximum in the evening, between five and eight o'clock 

 (37*5 C.) (Fig. 143). The extreme daily range in health 

 may be taken as a little over i C., or about 2 F. In fever 

 it is generally greater, but the maximum and minimum fall 

 at the same periods ; and it is of scientific, and also of 

 practical, interest that the early morning, when the tempera- 

 ture and pulse-rate are at their mininum, is often the time 

 at which the flagging powers of the sick give way. From 

 two to six o'clock in the morning the daily tide of life may 

 be said to reach low-water mark. Even in a fasting man 

 the diurnal temperature curve runs its course, but the varia- 

 tions are not so great. The taking of food of itself causes an 

 increase of temperature, although in a healthy man this 

 rarely amounts to more than half a degree. The rise of 



