METABOLISM AS AFFECTED BY GROWTH. 107 



errors and average the two lowest periods? Obviously, if 315 calories 

 had been the result of duplicate simultaneous determinations, its 

 validity could hardly be questioned. 



In an earlier communication 1 we emphasized strongly the relation- 

 ship observable between the pulse-rate and the total metabolism. The 

 pulse-rate for the four periods in this experiment varied only between 

 111 and 119. In the earlier observations just referred to, special 

 stress was laid upon the countings of the pulse-rate to secure a suf- 

 ficiently large number of counts to use for comparison with the metab- 

 olism which was simultaneously determined. In the present studies- 

 the records of the pulse-rate were necessarily subordinated in many 

 instances to other technique. The average of 111 for the pulse-rate 

 in the first period does not, therefore, necessarily represent the same 

 number of counts as does the average of 119 for the fourth period. 

 Effort was made, however, to secure a sufficient number of counts to 

 give a representative average. In this observation the lowest carbon- 

 dioxide production per hour (that of the fourth period) occurred when 

 the pulse-rate was actually the highest. Judging from these data alone, 

 the correlation between pulse-rate and metabolism is by no means 

 positive and gives no further evidence of the validity of the value for 

 the metabolism in this fourth period. 



A second observation of 6 periods was secured on the next day (June 

 16). The high carbon-dioxide production for the preliminary period 

 of 50 minutes (which is here given as 7.91 grams per hour) is readily 

 accounted for by the activity in this period represented by the arbi- 

 trary designation IV. An accentuation of the pulse-rate is also found 

 in this period, with a rate of 126 beats. The agreement in the carbon- 

 dioxide production for the several periods of the main experiment is 

 reasonably close, the values ranging from 4.34 to 4.93 grams per hour. 

 The two lowest values, 4.38 and 4.34 grams, were coincidental with 

 periods in which the activity was but I. For this day it is obvious 

 that 4.34 grams of carbon dioxide, or from 318 to 321 calories, may 

 justifiably be considered as the minimum. This amply confirms the 

 single low value of 315 calories noted for the fourth period of the day 

 before. While, therefore, the value for the last period on June 15 

 gave a true measure of the basal metabolism on this day, it has far 

 greater weight from its substantiation by the values found in the two 

 periods on June 16. 



There was an interval of 5 months between the observation of June 

 15 and the next on November 22, during which there was a consider- 

 able increase in the length and weight of the child. The higher values 

 for the carbon dioxide are thus easily explained by these increases. 

 On November 22 we have but one period with the lowest grade of 



1 Benedict and Talbot, Carnegie Inst. Wash. Pub. No. 201, 1914, p. 130. 



