146 NATURAL INHERITANCE. [CHAP.
also shown from his data, that yeux g?-is (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 (and I have fourteen of these) is capable of yielding three such groups. Thus, group 1 contains a, the " children;" b, the parents ; c, the grandparents. 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 grandparents 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
