SEX. REST AND WORK. 925 



That young individuals show a more active metabolism than adults, 

 follows, as above stated, principally from the relatively greater body 

 surface in the first as compared to the latter. According to TIGERSTEDT 

 and SONDEN, the greater metabolism in young animals depends neverthe- 

 less, also in part, on the fact that in these individuals the decomposition 

 in itself is more active than in older ones. The period of growth has a 

 considerable influence on the extent of metabolism (in man), and indeed 

 the metabolism, even when calculated on the unit of surface of body, is 

 greater in youth than in old age. This view is strongly disputed by 

 RUBNER. He does not deny that differences exist between young and 

 adult individuals which may be considered as a deviation from the above 

 rule; still these differences may, he claims, be dependent upon the work 

 performed, the food, and the nutritive condition. MAGNUS-LEVY and 

 FALK 1 have reported observations which support the conclusions of 

 SONDEN and TIGERSTEDT. 



Nurslings have a behavior different from older children, as with them 

 during the first months of life, and especially the first three days, the 

 metabolism, calculated on the unit of surface, is strikingly low, and 

 lower than with adults. After about two weeks it attains about the same 

 height as adults (SCHERER, FoRSTER 2 ). 



In old age the metabolism is very much reduced; and even when calcu- 

 lated upon the square meter of surface of body it is lower than in an* 

 individual of medium age. 



The question as to what extent sex specially influences metabolism 

 remains to be investigated. TIGERSTEDT and SONDEN found that in 'the 

 young the carbon-dioxide elimination, per kilo of body weight, as well as 

 per square meter of body surface, was considerably greater in males 

 than in females of the same age and the same weight of body. This 

 difference between the sexes seems to disappear gradually, and at old 

 age it is entirely absent. The investigations of .MAGNUS-LEVY and 

 FALK oppose these observations. They investigated by means of the 

 ZUNTZ-GEPPERT method, not only children, but also adults and old 

 persons of both sexes, but could not observe any positive influence of 

 the sex upon metabolism. 3 



ir Figerstedt and Sonden, Skand. Arch. f. Physiol. 6; Rubner, 1. c.; and Arch. f. 

 Hygiene, 66; Magnus-Levy, Arch. f. (Anat. u.) Physiol., 1899, Suppl. 



2 Cited by A. Loewy in Oppenheimer's Handb., Bd. 4, 189. 



Tigerstedt and Sonden, Skand. Arch. f. Physiol., 6; Magnus-Levy and Falk, 

 Arch. f. (Anat. u.) Physiol., 1899, Suppl. In regard to metabolism and its relation 

 to the phases of sexual life and especially under the influence of menstruation and 

 pregnancy, see the investigations of A. Ver Eecke (Bull. acad. roy. de me"d. de Bel- 

 gique, 1897 and 1901, and Maly's Jahresber., 30 and 31). See also Magnus-Levy 

 in-v. Noorden's Handb. d. Pathol. d. Stoffwechsels. 



