NORMAL PROCESSES OF ENERGY METABOLISM 643 



tempting to arrive at truly basal conditions. The environing temperature 

 was different in the groups of cases cited, but the fact that quiet sleep was 



TABLE 30 



AVERAGE MINIMAL METABOLISM OF NORMAL INFANTS 

 (All sleeping or nearly quiet) 



* No details given by authors for three of these infants. 



/ 



induced may be accepted as proof that the clothing was properly adapted 

 to the temperature of the chamber. 



We pass now to a consideration of the two factors just mentioned: 

 namely, (1) the dynamic action of food, and (2) the influence of age upon 

 the metabolism. 



3. Dynamic Action of Foods in Infants. It will be seen later that 

 the average energy metabolism of the sleeping infant from two months 

 to one year of age is about 2^ times that of the adult on the basis of 

 weight. This means that the alimentary tract of the infant must be at 

 least two and one-half times as active as that of the adult in order to 

 supply to the circulation the materials necessary for combustion. Added 

 to this is the requirement for growth. It might be expected a priori, there- 

 fore, that the proportionately more rapid streaming of materials into 

 the blood (see page G05) would sot up a greater dynamic effect in the in- 

 fant than in the adult. The evidence to date, however, is that the reverse 

 is true. 



Rubner and Heubner(6) were of the opinion that they had demon- 

 strated a dynamic effect of cow's milk when they found in their second 

 study a higher heat production in an artificially-fed infant of T 1 /^ months 

 than in their first breast-fed infant of nine weeks. Using the latter as a 

 basal experiment, they calculated that a diet of cow's milk containing 44 

 per cent more than the maintenance requirement of energy had raised the 

 metabolism in the former 9.7 per cent The difference in the ages of 

 the two infants together with the absence of certainty that the second 



