NORMAL PROCESSES OF ENERGY METABOLISM 653 



of Scharling; but it is not until the classic investigation of Sonden and 

 Tigerstedt that definite proof is furnished. While the conditions of ex- 

 perimentation were not those recognized to-day as essential to demon- 

 strate a basal difference, the authors are very positive in their opinion that 

 under like conditions in the young the CO 2 output both per kilogram of 

 weight and per square meter of surface (Meeh) is considerably greater in 

 males than in females (see page 656). The average difference for their 

 age series (see below, Table 38) is as 140 : 100, "This difference appears 

 to vanish gradually with increasing age until in old age it disappears 

 completely." 



DuBois(a) first drew attention to a probable difference of actual basal 



2kgs. 6 



10 



14 



18 



22 



26 30 34 38 42 



Fig. 43. Comparison of basal heat production of boys and girls per 24 hours referred 

 to body-weight (Benedict and Talbot). 



metabolism between the sexes in children (Fig. 35, p. 613) upon the basis 

 of the observations of Magnus-Levy and Falk, who did not themselves rec- 

 ognize such a difference. Its demonstration, however, is due to Benedict 

 and Talbot (c). They find that the absence of a sexual difference for the 

 very young infant (p. 635), "persists until about the weight of 11 kgm., 

 but that frequently there is a tendency for the boys to have a somewhat 

 higher metabolism (average) than girls of the same weight" (Fig. 43). 

 On the basis of surface they find that the two sexes remain at, essentially 

 the same metabolism (average) until the surface reaches 0.48 sq. M. 

 (DuBois). "From this point the line for the boys rises above that for 

 girls and there is no evidence of a tendency for the two lines to cross 

 later." 



