ELEMENT OF NOVELTY IN MEASUREMENTS OF METABOLISM. 97 



Aside from the physical difficulties met with in attempting to secure 

 measurements of the metabolism of children under true basal condi- 

 tions, we have to deal with the possibility of an incipient acidosis. 

 With adults, complete fasting soon produces a reduction in the store 

 of glycogen and shortly thereafter acidosis sets in. The earlier 

 experiments of Schlossmann and Murschhauser 1 seemed to show that 

 this acidosis appeared much earlier with children than with adults. 

 Experience in this laboratory, both with a fasting man 2 and with 

 diabetics, 3 indicates strongly that the metabolism is noticeably stimu- 

 lated by acidosis. As has been shown in other publications, it becomes 

 a serious problem to decide upon the exact point when the stimulating 

 effect of food ceases and the stimulus of acidosis begins. Even with 

 adults this point has never been sharply denned, although from the 

 general trend of metabolism during long experiments it appears that a 

 minimum is reached not far from 10 to 12 hours after the last food is 

 taken, unless the last meal was particularly rich in protein. Since 

 one may designate the measured metabolism of these younger children 

 only as approximating basal, comparisons between these values and 

 true basal values for adults must be made with extreme caution. 



THE ELEMENT OF NOVELTY IN MEASUREMENTS OF 



METABOLISM. 



Throughout our entire series of experiments we were frequently con- 

 fronted with the question as to how much of a role the element of 

 novelty played in the determination of metabolism. Naturally, when 

 the children went into the respiration chamber for the first experi- 

 ment, their attitude toward the apparatus was somewhat different 

 from that in the second experiment. While every effort was made to 

 accustom the children to seeing the apparatus in working order and 

 to assure them that there was nothing distressing or uncomfortable 

 in the experiments, the novelty of being placed inside the respiration 

 chamber might conceivably affect the basal metabolism; hence values 

 secured on the first day might be looked upon as aberrant. 



For a strict comparison of the results obtained under the two con- 

 ditions, it is important in the first place that the two days be reason- 

 ably close together, so as to eliminate the factors of age and weight. 

 Secondly, the periods for comparison must be of the lowest order of 

 activity; that is, the child should preferably be in complete repose in 

 both periods. After a careful scrutiny of our data, we have selected a 

 number of experiments with children of both sexes and varying ages, 

 which give suitable data for such comparison. These are brought 

 together in table 24, which shows the heat production on the 24-hour 



1 Schlossmann and Murschhauser, Biochem. Zeitschr., 1913, 56, p. 396. 



J Benedict, Carnegie Inst. Wash. Pub. No. 203, 1915, p. 365. 



3 Benedict and Joslin, Carnegie Inst. Wash. Pub. No. 176, 1912, pp. 125 and 134. 



