72 PHYSIOLOGY CHAP. 



exchange of material and energy to the inversion of the two 

 phases, positive and negative, of its functional tone is undoubtedly 

 the result of habit. Toulouse and Pieron . observed a complete 

 inversion of the curve of temperature in the case of nurses 

 obliged for a long period to watch by night and sleep by day. 

 This inversion of temperature, however, was only obtained after 

 several weeks, when the nurses had become thoroughly accustomed 

 to their new mode of life. 



Galbraith and Simpson (1903) obtained the same result in 

 monkeys after keeping them for some time in pitch darkness 

 during the day and in the light during the night. When these 

 animals were kept for the whole time during which they were 

 under observation either continuously in the dark or in the 

 light, the characteristic daily curve disappeared and there were 

 only irregular variations in the temperature. Worthy of note 

 is the observation of these investigators, that in night birds the 

 daily curve is the reverse of the normal one characteristic of day 

 birds, which seems a direct confirmation of the older teaching 

 of Chossat. 



III. The average temperature varies but little with age. The 

 temperature of the foetus is somewhat higher than that of the 

 mother (H. Eoger). The temperature of the rectum of the infant 

 immediately after birth is, according to repeated observations 

 made by Barensprung, 37'81, while the normal temperature of 

 the uterus is 37'5. According to Eoger the temperature of 

 the arm-pit of the new-born child is 37'75, that of the mother 

 being 3675. Half an hour after birth it is 37'6 ; ten hours after 

 37-05 (Andral). 



The relative hyperthermia of the foetus and the new-born 

 child is due to the combustion in the foetal organism itself; the 

 gradual hypothermia constantly noticed after birth is probably 

 due to the imperfect development of its nervous system, the 

 regulator of the temperature, and in this respect the new-born 

 child resembles hibernating animals. 



A few days after birth the temperature of the child becomes 

 much the same as that of the adult. The temperature of old 

 people does not differ much from that of adults. Charcot found 

 the temperature of the rectum in the old to be 37'2-37'5, and 

 that of a healthy centenarian to be 37'1 in the arm-pit and 38 

 in the rectum. Mosse and Ducamp, in 180 cases observed, found 

 an average difference in the temperature of the arm -pit and 

 rectum in old people of 75-80 years of age to be 0'45. In the 

 morning the temperature of the arm -pit was 36'32, in the 

 evening 36'46, about a tenth of a degree lower than in middle- 

 aged persons. 



Sex exercises no sensible influence on the average temperature. 

 Roger in ten boys found the average temperature to be 37107 



