EVOLUTION 459 



We see that, on the average, the intensity of parental 

 correlation is about .3 to .5, of grandparental about 

 .15 to .3, and of fraternal about .4 to .6, the latter corre- 

 lation being somewhat reduced when the " fraternity " 

 consists of members of opposite sexes. We shall find later 

 that there are theoretical grounds for supposing that the 

 intensity of heredity in cases of blended inheritance zvitk 

 panganiy are very nearly given by the lower limits, .3, .15, 

 and .4. 



§ 8. — On Prepotency and Tclegony 



We see now that the important question of prepotency 

 can be definitely settled for any organ and any pair of 

 relatives. We have only to investigate whether there is 

 a sensible difference between the coefficients of heredity 

 determined in the manner indicated in the last section. 

 Thus without entering here into a general theory of how 

 prepotency is distributed with regard to sex and character, 

 we may draw some general conclusions to illustrate 

 method. Thus we find : — 



{a) That the father is prepotent in the matter of 

 stature, and this for offspring of both sexes. 



{b) That the intensity of heredity is stronger in the 

 son than in the daughter for both stature and shape of 

 head. This appears to be only part of a much more 

 general rule, i.e. that the male inherits more than the 

 female ; for I have found on investigating the inherit- 

 ance of eye-colour, that taking the eight possible grand- 

 parental and the eight possible avuncular relationships, 

 the rule holds with only one exception. 



{c) That allowing for the prepotency of the male the 

 hereditary resemblance between relatives of the same sex 

 is greater than that between members of the opposite sex. 

 This rule is seen when we compare brother and brother, 

 or sister and sister with brother and sister in the above 

 table. Pairs of the same sex are more alike than pairs of 

 the opposite sex. This is true for eye-colour, as well as 

 for stature, head-index, and coat-colour. 



