ENERGY CALCULATION IN INFANCY 523 



From these facts the author is inclined to believe (as, too, 

 from the objections of Zuntz and his pupils and those of 

 H. Friedenthal and others) that we may conclude that main- 

 tenance exchange does not depend merely upon the surface 

 area of the body, but also, and in very distinct manner, upon 

 the amount of active protoplasm, and doubtless also upon a 

 number of other items which we cannot entirely overlook. 20 



The female sex does not show any lower activity in main- 

 tenance metabolism than the male ; but in senility there is a 

 notable diminution, and in childhood exchange is always 

 distinctly higher than in adult life, whether determined in 

 relation to body weight or to surface area of the body. If 

 the amount of gas interchange in a man be taken as 100, 

 according to Magnus-Levy and Falck, it is 78 in a senile 

 individual and in the child it may reach about 110. 



Energy Calculation in Infancy. Special attention 

 should be devoted to the energy calculation in infancy. The 

 infant's exchange is peculiar in that, even when determined 

 for the surface unit, it is decidedly low during the first month 

 of life, and only reaches by a gradual rise the level char- 

 acteristic of childhood about the end of the third month. 21 

 The method of energy computation introduced by Camerer 

 into the study of child nutrition has since come to be a mat- 

 ter of considerable consequence to pediatrists. Heubner and 

 Eubner have attempted to systematize the matter of energy 

 recording in infants, deducting from the "native calories" 

 of the food the number of calories lost in the faeces and urine 

 and thus arriving at the "net calories" which are actually 

 available to the infant. By dividing the number of native 

 calories introduced into the body by the body weight Heub- 

 ner 's energy-quotient is obtained, which refers to the num- 



20 Cf. A. Lowy, Handb. d. Biochem., 4', 186, 1908; H. Friedenthal (Lake 

 Nicholas, Berlin), Centralbl. f. Physiol., 23, 437, 1909; J. Howland (Graham 

 Lusk's Lab., New York), Zeitschr. f. physiol. Chem., 74, 1, 1911. 



21 Cf. A. Lowy, Handb. d. Biochem., 4', p. 189, 1908. 



