16 build: definition and ontogeny. 



leg-length. Likewise the leg-length of the gorilla is about 70 per cent 

 that of a European man (German, cf. Martin, 1914, p. 308). Con- 

 sequently the relative leg-length of the infant, at birth, is to that of the 

 adult as the relative leg-length of an anthropoid ape is to the relative 

 leg-length of man. Incidentally, it may be added that the relative 

 length of the arm of the infant is only slightly (8 per cent) less than 

 that of the adult, while in the chimpanzee the relative arm-length is 

 18 per cent greater than that of man. 



We have seen that the relative leg-length of the boy increases to 

 about 12 years and thereafter diminishes to the period of completed 

 growth. The white man has his greatest leg-length shortly before 

 adolescence. We find that among the races of mankind it is the long- 

 legged negro tribes of East Africa, especially the upper Nile (Johns- 

 ton, 1906, II, p. 932), which are among the lowest races of mankind, 

 and which seem to represent in the adult the physical stage through 

 which the white boy passes at 12 years. Other African tribes have, 

 indeed, relatively shorter legs and thus show a persisting adult stage 

 that is either slightly younger or slightly older than that of the 

 12-year-old white boy. 



Figure 1 (to return to it after this digression) seems thus adequately 

 to measure the varying build of humans from birth to past maturity. 

 It may, indeed, be regarded as composed of two parts ; first, that from 

 birth to the cessation of growth in stature, and second, that beyond 

 cessation of growth in stature. 



The curve of build thus obtained is, apart from the first period of 

 adjustment that follows birth, a smoothly flowing one, that might 

 indeed be expressed by a formula 



y = ax + bx 2 + cx s + dx*, etc. 



The curve of build of figure 1 seems to be new in this form. It is, 

 however, of the same general shape as the curve of varying "Korper- 

 fiille" drawn by Martin (1914, p. 246) from Quetelet's data and based 

 on the relation of weight -j- stature 3 . The numbers of children con- 

 sidered in Martin's figure are inadequate and there is hardly sufficient 

 justification for the use of this formula to express changes of build 

 during ontogeny. 



The ontogenetic curve of build may serve as a graphic representa- 

 tion of the stages of development as listed by Stratz (1922). These 

 stages are shown in table 5. 



Later Ontogenetic Changes in Individual Build. 



Any investigation of the heredity of build is apt to meet with the 

 difficulty that only the present weights and statures of children, par- 

 ents, and grandparents are known; that the persons are of different 

 ages and hence the data concerning them are not precisely com- 



