METABOLISM AS AFFECTED BY GROWTH. 109 



three weeks later (February 19). In one instance food containing 260 

 calories was taken immediately before the observations began; in the 

 other, food containing 470 calories was given 30 minutes before the 

 observations. The carbon-dioxide production and total heat pro- 

 duction on February 19 are noticeably greater than those for January 

 31, but owing to a coincidental increase in body-weight, the heat 

 production per kilogram of body-weight and that per square meter 

 of body-surface are practically unaltered. 



The pulse-rate for February 19 is distinctly higher on the average 

 than on January 31, although in both observations the subject is 

 reported as being asleep, with, if anything, the lesser activity on the 

 second day. A complicating circumstance here is the fact that on 

 February 19 there was a slight rise in rectal temperature, the record 

 at the beginning of the observations being 99.8 F. and that at the 

 end 100.5 F. The possible influence of food and the possible influence 

 of a slightly febrile state are thus commingled and no sharp deductions 

 can be made. 



The influence of a slightly febrile temperature seems to be more 

 marked upon the pulse-rate than upon the metabolism itself. On the 

 two days when slightly febrile temperatures were noted, namely, on 

 February 19, and April 2, 1917, the pulse-rates were noticeably higher 

 than on the days immediately before or after. A corresponding 

 increase in the metabolism is not always definitely noted. Still, the 

 very fact that the pulse-rate was so obviously disturbed by this slight 

 rise in temperature makes it all the more important to avoid the use 

 of observations when the body temperature is even slightly febrile, 

 especially in comparison experiments. 



Perhaps one of the most pronounced instances of the influence of 

 food is that shown by comparing the tests of May 18 and June 20, 

 1917. In the second observation it would appear as if the influence 

 of food was clearly present, although the minimum value of 47 calories 

 per kilogram of body-weight is but 10 per cent above the minimum of 

 May 18. After the age of 2 years, the food was almost invariably 

 taken 4 to 5 hours prior to the observations and hence may be con- 

 sidered as of comparatively little effect. After that age, the calories 

 in the food represent not far from one-third to one-fifth of the daily 

 requirement. Experience with adults would imply that at the end 

 of 4 hours the peak of the stimulating effect of food would have been 

 considerably passed. In none of these observations, therefore, 

 have we the ideal condition of the post-absorptive state. The fact 

 that in most cases the observations were made with the child asleep, 

 and that in many instances, especially in the later years, the food had 

 been given 4 or 5 hours before, undoubtedly minimizes and compen- 

 sates the influence of the ingestion of food. Still, in any comparison 

 of the metabolism of children at varying ages, it must constantly be 



