RELATIVES ON THE SUPPOSITION OF MENDELIAN INHERITANCE. 427 
of span this seems likely, the correlations for uncle and cousin will be the same as 
those for grandparent and great-grandparent, being given by the formulae 
and 
/ 1+AV 
leading to the numbers 
Stature. 
Span. 
Cubit. 
Grandparent . 
•3502 
•2907 
•2737 
Great-grandparen t 
•2421 
1861 
•1793 
24. Neither these nor the similar table for the first hypothesis accord ill with 
the value obtained for uncle and nephew, '265, from measurements of eye colour. It 
may, however, be thought that neither of them give high enough value for cousins. 
Certainly they do not approach some of the values found by Miss Elderton in her 
memoir on the resemblance of first cousins ( Eugenics Laboratory Memoirs, iv). 
Series are there found to give correlations over '5, and the mean correlation for the 
measured features is '336. From special considerations this is reduced to '270, but 
if the similarity of first cousins is due to inheritance, it must certainly be less than 
that between uncle and nephew. No theory of inheritance could make the correla- 
tion for cousins larger than or even so large as that for the nearer relationship. 
It will be of interest finally to interpret our results on the assumption that the 
figures quoted (Article 20) represent actual coefficients of selection. Manifestly it 
would be better to obtain the value of A experimentally from the ratio of the 
ancestral correlations, using the collateral correlations to determine what are the 
marital correlations for y. For the present we must neglect the possibility of an 
independent selection in y ; and although we know that the figures are not final, we 
shall write s, the coefficient of selection, equal to '2374, '0053, and '1043 in our 
three cases. 
Further, let 
so that 
whence we deduce 
2 i> = <h 
c 2 (l + s) + fjL - s, 
Stature. 
Span. 
Cubit. 
c x c 2 
. -7841 
•7108 
•6725 
A . . . 
. -2410 
•2761 
•2090 
i(l + A) . . 
•6205 
•6381 
•6045 
the values of A being now in much 
closer agreement for 
the three features. 
Further, from the fraternal 
o 
o 
CD 
£7 
trt- 
o’ 
we have 
C ± . 
with a mean at ‘9821. 
. 1-0112 
1-0370 
■8940 
Again, for the dominance ratio 
•2763 -3880 '2940 ’3194 (mean), 
leaving a trifle under 2 per cent, for causes not heritable, but requiring high values 
about '32 for the dominance ratio. 
