NORMAL PROCESSES OF ENERGY METABOLISM 649 



They conclude that children produce more heat not merely for the 

 reason that their superficial area is greater in relation to their weight 

 but more also on account of the increased vital energy characteristic of 

 youth. 



Sonden and Tigerstcdt in the course of an extensive investigation on 

 the metabolism of children sitting quietly as in school, which will be pre* 

 sented later, obtained results on two boys 11.2 and 12 years of age re- 

 spectively while sleeping. They found the CO 2 elimination on the basis of 

 surface area (Meeh) 52 

 per cent higher than that 

 of adults in sleep. While 

 the conditions of these 

 experiments did not ex- 

 clude the influence of 

 food altogether, they ap- 

 proached the true basal 

 conditions very closely 

 and furnished early evi- 

 dence of a variation di- 

 rectly caused by a differ- 

 ence in age. The con- 

 clusion of these authors 

 agrees with that of Mag- 

 nus-Levy and Falk that 

 the youthful body in and 

 of itself independently of 

 its smaller size possesses PULSE 

 a more active metab- 

 olism. 



1. Basal Metabolism 

 of Children up to Pu- 

 berty. Among the sub- 

 jects studied at intervals 

 over a long period of time 

 by Benedict and Talbot(c) was a girl, designated in their series as Xo. 

 145, whose record extends from the age of five months to the age of three 

 years and five months. In all she was placed in the respiration chamber 

 on thirty-one different days and the observational periods of approximately 

 30 minutes each numbered 4 to 5 daily. The minimal metabolism is 

 given for 25 different days and the accompanying chart represents 19 

 distinct points in the course of the three years (Fig. 38). 



The most rapid growth (as would be expected) is seen in the first half 

 of the time, namely from the 5th to the 21st month. During this time the 

 basal metabolism, calculated to 24 hours (called "total calories" in thq 



Mos.3 



12 



39 42 



Fig. 38. Body-weight, pulse-rate and basal metab- 

 olism per 24 hours of a girl from 5 months to 41 

 months of age (Benedict and Talbot). 



