PROFESSOR K. PEARSON AND DR. A. LEE ON 
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the avuncular and the fraternal correlation in the cases of both horse and man, it is 
yet in both these cases unsatisfactory so far as the grandparental inheritance is con¬ 
cerned. It may be imagined that if we allowed for reversion, we might emphasise 
the grandparental correlation beyond the value '25 suggested by theory. But I 
have shown in my memoir on the “ Law of Reversion,” that with the parental correla¬ 
tion as high as '5, we cannot hope to have the grandparental correlation even with 
reversion higher than '25. (See ‘ Roy. Soc. Proc.,’ vol. 66, p. 140 et seq.) Clearly the 
values obtained for grandparental correlation in this paper—the first I believe 
hitherto investigated—seem to present anomalies which our theory of blended 
inheritance totally fails to account for, and which may require some modification of 
our views on reversion before we can meet them on our theory of exclusive 
inheritance. 
I note the following general results deduced from our values of the grandparental 
correlations :— 
(i.) Grandsons are more closely correlated with both grandparents than grand¬ 
daughters are. This is true for three out of the four cases; the exception, maternal 
grandmother, is covered by another rule (iv.). The mean correlation for grandparents 
and grandsons is ‘3294, and for grandparents and granddaughters 'SOSO. 
(ii.) Grandfathers are more closely correlated with grandchildren than grand¬ 
mothers are. This is true in three out of the four cases, the fourth being again 
subject to rule (iv.). The mean correlations for grandfathers and grandmothers are 
‘3675 and ’2658 respectively. 
(iii.) Paternal grandparents appear to be more closely correlated with their 
grandchildren than maternal grandparents, the average values of the two correlations 
being '3236 and ‘3097 respectively. 
(iv.) Resemblance between individuals of the same sex is closer than between 
individuals of the opposite sex. The mean values for the grandparental and 
grandchild correlation in the same and the opposite sexes are '3329 and '3004 
respectively. 
(v.) Grandfathers are. more closely related to grandsons than grandmothers to 
granddaughters, the mean correlations being as '3965 and ‘2693 respectively. It 
will be noted at once that these five rules are identical with those we have obtained 
for the avuncular correlations. So that there is small doubt that they are general 
rules relating to all grades of relationship for this character. 
It seems to me probable that the correct form of (iii.) is : Paternal grandfathers are 
more highly correlated with grandchildren ('4006) than maternal grandfathers ('3343), 
and paternal grandmothers (‘2468) less highly correlated than maternal grandmothers 
(2851). I have not stated the rule in this form, because it is not confirmed by 
the corresponding results for uncles and aunts. Paternal uncles (’3024) are more 
closely correlated with nephews and nieces than maternal uncles (’2722), but paternal 
aunts (’2414) are slightly more instead of less correlated with nephews and nieces 
