186 METABOLISM AND GROWTH FROM BIRTH TO PUBERTY. 



was 909 calories, while at 12 years and 1 month it had risen to 1,179 

 calories, or an increase of nearly 30 per cent. The general picture is 

 therefore essentially the same as that noted in figure 23 for the total 

 calories referred to age. 



When the caloric output per square meter of body-surface is referred 

 to body-weight, as in figure 43, a wide difference in the heat production 

 per square meter at these two weights is exhibited. While, therefore, 

 the great difference in total heat production noted on the chart for 

 total calories referred to age (fig. 23) is in large part removed by refer- 

 ence to heat production per kilogram of body-weight (fig. 31), there 

 still remains a very striking difference between the prepubertal and 

 pubertal stage when the heat production per square meter is con- 

 sidered. Precisely the same order of differences is to be observed with 

 this girl when the total calories are referred to the surface and the 

 calories per square meter are referred to surface in figures 39 and 41, 

 respectively. 



What little evidence, if any, can be drawn from these charts for 

 boys and girls as to the influence of prepubescence and the establish- 

 ment of puberty on metabolism may be summed up in the statement 

 that prior to puberty there is no tendency for a change in the general 

 trend of the basal metabolism. The establishment of puberty in at 

 least one girl resulted in a relatively high metabolism, which was made 

 clear by measurements both prior to and subsequent to the establish- 

 ment of puberty. Sonden and Tigerstedt 1 and Olin 2 report no increase 

 per kilogram or per square meter following puberty. 



Since with our boys and girls we did not find the increase in metab- 

 olism which Du Bois found, it becomes necessary for us to disagree 

 with his findings for boys 12 and 13 years old, and we believe our con- 

 clusion is justified, that the prepubescent period is without significant 

 effect upon the metabolism of the boy or girl. The evidence regarding 

 the effect of puberty fully established is sufficiently divergent in the 

 existing researches to warrant much further study on this important 

 point. Du Bois's evidence indicates strongly a decrease in metabolism 

 following the prepubescent stage. The very meager evidence we 

 possess indicates a tendency to an increase, although admittedly this 

 is largely based upon the measurements of one girl, which were made 

 before and after the establishment of puberty. Had not the question 

 of the influence of puberty upon the metabolism been raised by earlier 

 investigators, we should not feel that we were in any way justified on 

 the basis of this one experiment in discussing the question. We 

 believe that the chief point to be raised here is that further studies 

 with children of this age are imperative. Such investigation is now 

 in progress at the Nutrition Laboratory. 



1 Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 6, p. 75. 



2 Olin, Skand. Archiv f. Physiol., 1915, 34, p. 432. 



