140 NATURAL INHERITANCE. [CHAP. 



also shown from his data, that yeux gris (which I take 

 to be the equivalent of my hazel) are referable to a 

 light ancestry rather than to a dark one, but his data 

 are numerically insufficient to warrant a precise estimate 

 of the relative frequency of their derivation from each 

 of these two sources. 



In the following discussion I shall deal only with 

 those fraternities in which the Eye-colours are known 

 of the two Parents and of the four Grand- Parents. 

 There are altogether 211 of such groups, containing 

 an aggregate of 1023 children. They do not. however, 

 belong to 211 different family stocks, because each 

 stock which is complete up to the great grand-parents 

 inclusive (arid I have fourteen of these) is capable 

 of yielding three such groups. Thus, group 1 contains 

 a, the " children ; " b, the parents ; c, the grand- 

 parents. Group 2 contains a, the father of the 

 " children " and his brothers and his sisters ; b, the 

 parents of the father ; c, the grand-parents of the 

 father. Group 3 contains the corresponding selections 

 on the mother's side. Other family stocks furnish two 

 groups. Out of these and other data, Tables 19 and 

 20 have been made. In Table 19 I have grouped 

 the families together whose two parents and four grand- 

 parents present the same combination of Eye-colour, 

 no group, however, being accepted that contains less 

 than twenty children. The data in this table enable 

 us to test the average correctness of the law I desire 

 to verify, because many persons and many families 

 appear in the same group, and individual peculiarities 



