in 



THE COEFFICIENT OF VARIABILITY 



129 



epoch after birth are growing rapidly and are already "big for their 

 age"; and .others, of retarded development, who are comparatively 

 small and have not reached the period of acceleration which, in 

 greater or less degree, will come to them in turn. In other words, 

 there must under such circumstances be a strong positive "coefl&cient 

 of correlation" between stature and rate of growth, and also between 



§ 20 



7 8 9 10 II 12 13 14 15 



Age in years 



Fig. 24. Coefficients of variability, in annual increments of stature. 

 After Boas. 



the rate of growth in one year and the next. But it does not by 

 any means follow that a child who is precociously big will continue 

 to grow rapidly, and become a man or woman of exceptional 

 stature *. On the contrary, when in the case of the precocious or 

 "accelerated" children growth has begun to slow down, the back- 



* Some first attempts at analysis seem to shew that the size of the embryo at 

 birth, or of the seed at germination, has more, influence than we were wont to 

 suppose on the ultimate size of plant or animal. See (e.g.) Eric Ashby, Heterosis 

 and the inheritance of acquired characters, Proc. R.S. (B), No. 833, pp. 431-441, 

 1937; and papers quoted therein. 



