NORMAL PROCESSES OF ENERGY METABOLISM 647 



TABLE 34 

 BASAL HEAT PRODUCTION FROM Two MONTHS TO ONE YEAR OF AGE 



H. Energy Metabolism of Children 

 up to Puberty 



Logically, as we now see very clearly, everything starts from the mini- 

 mal or mere maintenance requirement, although historically the order 

 has been quite different. The latest and in many respects the most com- 

 plete researches have been made upon the basal metabolism. It is proper, 

 however, to see how much had been learned regarding the basal needs 

 from earlier investigations. 



The Zuntz school headed by the late !N". Zuntz of Berlin had long 

 emphasized the necessity of eliminating the influence of muscular activity 

 and of food if results upon subjects of different size or age were to be com- 

 pared. Magnus-Levy and Falk, followers of Zuntz, employing the well- 

 known method of Zuntz and Geppert with which important results had been 

 obtained on the influence of muscular work in mountain climbing, in 

 marching, and in the treadmill, on the influence of altitude and on the 

 influence of digestion, undertook in 1899 an investigation on the influ- 

 ence of age on the basal metabolism. The subjects ranged from 2*/> 

 years to old age, including eleven boys and nine girls under fourteen 

 years of age. At the time of observation the subjects were all in the 

 nuchlern condition, which is Zuntz's term for the absence of digestion, i. e., 

 at least twelve hours since taking food, or, what has been called by others, 

 the "post-absorptive state." The subject lay upon a couch and suppressed 

 all muscular contractions. The Zuntz method as described on page 539 

 permits of the determination of oxygen absorbed as well as of CO 2 elimi- 

 nated. 



The results upon the group of children mentioned above are presented 

 in Table 35. The respiratory quotient characteristic of the nilchiern 

 condition in children is well illustrated in this table. The average is 

 0.82 for boys and 0.84 for girls. With adults the quotient is quite 

 commonly several points higher for the reason that adults do not consume 

 their store of glycogen quite so rapidly. This is in accord with the well 

 known fact that fasting is much more exhausting for children than for 

 adults. The capacity to handle carbohydrates in the diet is the basis 

 of the craving for sweets among children. The arrangement in Table 

 35, following that of the authors themselves, is according to weight rather 

 than age. It is apparent at once that the metabolism in both sex groups 



