150 
MATHEMATICAL CONTRIBUTIONS TO THE THEORY OF EVOLUTION. 
Fathers. 
Colours 
1-3. 
Colours 
4-8. 
Average 
of totals. 
Colours 
1-3. 
3-83 
4-57 
4-07 
Colours 
4-8. 
3-82 
3-73 
3-79 
Average 
of totals 
3-83 
4T7 
3-94 
Fathers. 
Colours 
1-2. 
Colours 
3-8. 
Average 
of totals 
Colours 
1-2. 
3-19 
4 - 52 
3-86 
Colours 
3-8. 
3-98 
3-96 
3-97 
Average 
of totals 
3-68 
4-09 
3*94 
The first table entirely confirms all the conclusions reached,—dark fathers and 
light mothers are most fertile absolutely and in union. The second table shows 
that it is the blue-green and grey rather than pure blue-eyed mothers who are most 
fertile. This supplementary investigation accordingly seems to support the view of 
the text of the memoir, namely that reproductive selection is the source of the 
secular change in eye-colour noted, only the prepotent fertility which is replacing the 
blue eyed element is in the first place that of the dark-eyed male, and only in the 
second place due to mothers having eye-colours dark or light other than true blue. 
We seem accordingly in eye-colour to have reproductive selection working through 
heterogamy rather than through liomogamy as in the case of stature.* The effect, 
however, is like,—the progressive elimination of one type of character.] 
* See 1 Roy. Soc. Proc.,’ vol. 66, p. 30, and vol. 66, p. 316 et seq. 
