METABOLISM AS AFFECTED BY GROWTH. 151 



Du Bois with boy scouts in his second series of experiments indicate 

 values a little below our projected general trend. 



This comparison, in which the influence of variations in weight is in 

 part eliminated, still shows that practically all of the values obtained 

 in the earlier work are on a higher metabolic level than ours. We are 

 thus forced to the conclusion that much of the earlier work was un- 

 wittingly affected by muscular activity to such an extent that it fails 

 to meet modern requirements for basal metabolism measurements. 

 Still, the general trend of the earlier work is not widely different from 

 that observed in our research, for a smoothed curve passed through 

 the points on the chart in figure 32 would be of approximately the 

 same order, although at a higher level than that shown by our results. 

 This suggests that the differences in the various series of observations 

 are due wholly to differences in the degree of approximation to basal 

 conditions. The earlier work does not, however, bring out the dis- 

 tinctly lower metabolism in the first few months of life which is so 

 clearly shown by the general averages of our more numerous data. 



The relatively few observations of earlier writers on girls make it 

 seemingly unnecessary to burden this report with a reproduction of 

 an additional chart comparing the values per kilogram of body-weight 

 referred to age for these investigators. It is sufficient to state that 

 all of the earlier values lie above our smoothed curve, with the excep- 

 tion of two of Magnus-Levy and Falk's girls at 11 and 12 years, both 

 of which lie but little below. The points for the Magnus-Levy and 

 Falk girls, however, are grouped about the curve with a distribution 

 not dissimilar to that for our own values. In general, all the girls 

 previously measured who were 10 years of age and over show a reason- 

 ably close agreement with our smoothed curve on the basis of calories 

 per kilogram of body-weight. 



The importance of studying the metabolism during youth was 

 clearly emphasized in the classical studies of Sonden and Tigerstedt, 1 

 but owing to the absence of conditions prerequisite for the determina- 

 tion of basal metabolism, the values are not strictly comparable and 

 only two could be used in the chart in figure 32. We have, however, 

 selected minimum carbon-dioxide periods and computed the minimum 

 calories per kilogram referred to age; these are plotted in figure 33 

 for boys. Upon the same chart we have laid our curve for basal 

 metabolism of boys from 7 to 16 years and likewise included the values 

 recently cited by Carl Tigerstedt 2 for boys from 9 to 14 years of age. 

 This last citation is preceded by a careful statement as to the im- 

 portance of muscular rest, and these values have accordingly been 



1 Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 6, p. 1. 



2 Tigerstedt, Carl, Ueber die Nahrungszufuhr des Menschen in ihrer Abhangigkeit von Alter, 



Geschlecht und Beruf, Helsingfors, 1915. See also Skand. Archiv f. Physiol., 1916, 34, 

 p. 151. 



