194 Prof. S. Ringer and Mr. A. P. Stuart on the 



We are now in a position to compare the temperature of persons 

 under 25 with that of persons over 40 years of age. 



Average daily maximum temperature of all the observations 



made on persons under 25 years 99° Fahr. 



Average daily variation of the temperature of the same 



persons 1 0, 9 



Average maximum temperature of persons over 40 98°* 8 



Average daily variation o, 87 



From this Table it appears that the daily variations in old people is 

 considerably less than that of young people ; in fact the variations in 

 persons over 40 is only half that of persons under 25 years. 



On the other hand, the daily maximum temperature is much the same 

 both under 25 and over 40. 



But the difference is not merely in the amount of depression, but in 

 the manner of its occurrence. In young people we get in the evening 

 a very rapid fall, and the minimum temperature of the day is quickly 

 reached ; often, indeed, in three or fours hours. In persons over 40, 

 whose temperature was taken through the day and night, so rapid a fall 

 rarely occurs ; but the temperature usually declines very slowly, and as 

 soon as the minimum is reached it again begins to rise, so that not ouly 

 is the amount of the evening fall less in these older persons, but the 

 period of the depression is also shorter, generally very much shorter. 



It may here be noted that on some days, even when the temperature 

 was observed for twenty-four hours, no diurnal variation occurred in 

 persons over 40 years of age. But the temperature of these older 

 differs in yet another respect from that of younger persons ; thus 

 apparently the diurnal fall does not observe any particular time, but 

 occurs sometimes in the middle of the night, and at other times in the 

 morning at about 9 a.m. 



Past II. 



Concerning the influence of Food on the Temperature of Healthy People. 



In a previous section a considerable diurnal variation in the tempera- 

 ture, often amounting to two degrees, has been shown to occur. 



It is important to ascertain whether this variation is produced by food 

 or is due to other causes. Our present section is devoted to the solu- 

 tion of these questions. 



"We shall at first turn our attention to the observations made on the 

 lads Eundell and Mountain. As these were continued night and day, 

 without any interruption, and as we have accurate accounts of the quan- 

 tity and the nature of their food, it is obvious we shall obtain much more 

 trustworthy conclusions from these than from less elaborate and exact 

 observations. 



These two lads were about twelve years of age. The observations 



