30 HEREDITY AND EUGENICS 



independent factors govern the size in different parts 

 of the bod}'. The correlation-coefficients obtained 

 were uniformly high, and Castle reaches the conclusion 

 that " the genetic agencies affecting size in rabbits 

 are general in their action, influencing in the same 

 general direction all parts of the body." 



This important contribution of Castle to the subject 

 of size-inheritance seems to indicate that, in so far as 

 rabbits are concerned, there is no certain evidence of 

 factors independently influencing the size of particular 

 organs. Castle applies the same views to mammals 

 and man, but not to plants where " hormone action 

 is less in evidence." He regards the view of the 

 genetic independence in size of the various parts of 

 the body as a " sporadic relapse into preformation- 

 ism," and denies that any lack of co-ordination of 

 organs, such as Davenport has suggested, can arise 

 through the crossing of different races of man. He 

 points out also, that the measurements used by 

 Davenport were not sufficiently precise to give reliable 

 correlation-coefficients, and criticises the photographs 

 of a Dinka negro and a Chiriguan Indian as evidence 

 that length of legs and trunk is independently 

 inherited. Castle suggests that there is the same 

 difference in proportions between a boy and a man 

 as between the Chiriguan Indian and the Dinka 

 negro, and that the latter, therefore, merely repre- 

 sents a later stage of development. He believes 

 that Southern Italians are short of stature and short- 

 limbed because they cease to grow early, while Swedes 

 and Scotch are tall and long-limbed because they 

 mature later, in the same way that Flemish rabbits 

 are large and have long ears because of their late 

 maturity. Davenport also recognises general growth 

 factors, and it is evident that the last word has not 

 yet been said on this important subject. What is 

 required is a mass of more accurate measurements. 



