PREVIOUS STUDIES OF THE METABOLISM OF CHILDREN. 21 



The pulse-rates in all instances but one showed a pronounced decrease 

 in the second series of experiments, L. B., for example, having a pulse- 

 rate of 88 in the first experiment and when two years older a pulse-rate 

 of 65. It seems almost impossible to ascribe this decrease in metab- 

 olism to a difference in age of two years, and this, combined with the 

 gross irregularities in metabolism in the two 1-hour periods in the 

 first experiment, and pronounced alterations in the pulse-rates, makes 

 it all the more desirable to have researches of this type include a 

 sufficient number of observations with each subject to establish 

 definitely the basal minimum metabolism for each individual. It is 

 clear that the average values used by Du Bois for the first series of 

 experiments are certainly not basal values. From the results of the 

 second series of experiments, in which the agreement between the two 

 periods is much more satisfactory, the authors consider that the metab- 

 olism per hour according to the Du Bois linear formula of the boys is 

 still higher than that of the average adult, the difference being about 

 11 per cent for boys 14 to 15 years old. 



CONTROL EXPERIMENTS AND BASAL METABOLISM. 



As will be seen from the foregoing abstracts of previous investi- 

 gations, the influence of both muscular activity and food was dis- 

 regarded in the earlier experimental work on metabolism; conse- 

 quently the values obtained in these researches were usually not 

 strictly basal. Most of this material was collected before the impor- 

 tance of absolute muscular repose was sufficiently recognized by 

 experimenters. Furthermore, ocular observations of the degree of 

 repose were used in the earlier studies, and these are untrustworthy, 

 since interpretations vary widely and accurate records are obtained 

 only by the graphic method. 



While these faults in technique have, in later days, been corrected 

 in large part, greater uniformity in experimental conditions and 

 standards should be the rule in all laboratories studying metabolism. 

 As emphasized in a previous section (see page 2), a knowledge of the 

 basal metabolism is very necessary, since it represents the basic 

 requirements of the human body to which the requirements for all 

 activities are added. According to modern conceptions of ideal 

 studies of the basal metabolism, which require the subject to be in 

 the post-absorptive condition (12 hours without food) and in com- 

 plete muscular repose, the basal metabolism is a perfectly definite 

 factor. Even if the values obtained are complicated by food, as in 

 some of the earlier experiments in this study of the metabolism of 

 children, yet the error can not be more than a maximum of 20 per 

 cent for short periods and rarely as high as this. 



The criticism has been raised that the conditions outlined for 

 obtaining the basal metabolism are not normal conditions, but this 



