MEASUREMENT OF BUILD. .". 



build from birth to maturity. This ratio, chest-girth -s-stature, has 



thus been used in discussing this law, as more fully described in g 

 tion B. This relation can be used for tracing the change in build of 

 the same developing child or for tracing the average change of build. 

 Adult. — In the study of adult changes of build we start with the 

 condition that in the individual the stature is fixed. Consequently, 

 in an individual whose weight is changing, the relation of the build at 

 a years is to that at another period n years later as chest -girth 

 at a years : chest-girth at a -f n years. Thus, in the adult period, 

 changes of build arc proportional to chest-girth. In different persons, 

 of differing stature, the stature has to be taken into account, and the 

 differences in build are measured by the relation of relative chest- 

 girth as in children. Unfortunately, in our study of heredity in adult 

 build, we usually do not know the chest-girth of the different mem- 

 bers of the family, but only their stature and weight. Our problem is, 

 then, to find a relation between chest-girth and weight that will 

 enable us to infer the one from the other. This problem will be further 

 considered in a later section (p. 24). 



Sexual Differences in Build. 



Sex influences the body so profoundly that we have, first of all. to 

 consider its influence on build, either in early or in adult stages. At 

 birth there is, on the average, a difference between the sexes in 

 weight. The male is about 2.5 per cent heavier than the female 

 (3,310 : 3.230 grams in German children, Daffner. 1902, p. 125, quoting 

 Hecker; 3,606 : 3,485 grams in American children, Benedict and Tal- 

 bot, 1915). But this does not imply that the boy baby is the 

 chubbier, since the boy baby is longer by about 1.7 per cent than the 

 girl baby. There is no obvious difference in the chubbiness of the 

 sexes at birth. Likewise, in later infancy no obvious difference has 

 been detected, though no thoroughgoing studies have been made on 

 this subject. In childhood and youth children of different sex differ 

 in build on the average, but this is because the form of the ontogenetic 

 curve of build is very different. After maturity and cessation of 

 growth, there is a marked difference in form between the sexes. The 

 female has more subcutaneous fat and appears plumper. If the 

 criterion of weight be applied, the complication arises that the specific 

 gravity of the female seems to be less than that o\ the male | Bardeen, 

 1920, p. 488, following Meeh, 1895). As found by Medico-Actuarial 

 Mortality investigations of the Associated Life Insurance .Medical 

 Directors of the Actuarial Society of America. 1912, volume I. p. 251 : 

 "The difference in weight between men and women iA the same 

 height is slight under the age of 20, but above that age young men 

 are distinctly heavier than young women, the difference becoming less 

 marked as they grow older. The tall women are markedly lighter 



