METABOLISM AS AFFECTED BY GROWTH. 139 



metabolism calculated with the American normal (multiple prediction) 

 formula for man that agrees remarkably well with that found, while 

 all the other values are much higher. With girls, therefore, as with 

 boys, the results of the earlier observations tend, in general, to have a 

 higher level of basal metabolism than was found in our series. 



GENERAL CONCLUSIONS AS TO TOTAL METABOLISM AND AGE IN CHILDREN. 



Our observations indicate a continually increasing metabolism from 

 birth to 13 years of age with both boys and girls. A slight deviation 

 in the general trend, as shown by the hypothetical smoothed curves 

 laid on these charts, suggests that the trend for girls is slightly different 

 from that of boys, especially about the age of 2 to 4 years. No other 

 sexual differentiation can at this point of the analysis be observed. 



Reference to all the available earlier observations suitable for 

 comparison as basal measurements shows that for boys, save in rare 

 instances, the observations always lie considerably above our line 

 representing the general trend. The scattered observations with girls 

 indicate substantially the same situation. From a careful analysis of 

 all the earlier experiments, we believe that the results of our observa- 

 tions more nearly approach the true basal values than those of the 

 previous investigations; hence, in lieu of further data, they must be 

 looked upon as the closest estimates of the true basal metabolism of 

 youth that have thus far been obtained. 



TOTAL METABOLISM WITH INCREASING BODY-WEIGHT. 



While physiological observations with children are commonly 

 referred to age, it is particularly unfortunate that the total metabolism 

 should be thus referred, for experience with adults has shown us that 

 a number of physiological factors play an important role in the total 

 metabolism, among these being body-weight, stature, and age. Of 

 these, body-weight has by far the greatest influence, much greater 

 than that of age; consequently we should more properly refer the 

 total number of calories per day to the body-weight rather than to 

 the age of the child. In general, the larger the child is, one would 

 a priori expect a greater metabolism. Furthermore, since we have 

 found that the metabolism increases with age, and since age and body- 

 weight, especially during the period of growth, go more or less hand 

 in hand, we should expect changes in metabolism to be in reasonable 

 conformity with changes in weight. Our curves representing the 

 relationship between total calories and age may simply be an ex- 

 pression of the fact that as children grow older they likewise grow 

 heavier, and the larger organism has a larger heat production. Physio- 

 logically, therefore, the better method of comparison is on the basis 

 of weight rather than of age. 



