II2 BIOMETRY 
character. The estimations were made by teachers 
having at least six months’ experience of the children 
in question. 
The method of statistical treatment was, as we have 
said, the same as that employed in the case of physical 
characters not capable of quantitative measurement, 
and there is little doubt that it is equally valid in the 
present case. We may well feel, however, some 
hesitation in accepting as sound the data to which the 
method is applied. At the best this data can only be 
of a roughly approximate kind. The evidence is, 
however, undoubtedly sufficient to establish the con- 
clusion that mental characters are inherited in man, 
and that they are probably inherited at a rate not 
greatly different from that at which physical characters 
are inherited. For it will be observed that the values 
given in Table VII. are in close agreement with one 
another, and that they also agree with the average 
value of fraternal correlation as found for a variety of 
physical characters both in men and in other animals. 
Assuming—and the assumptionseems to beareasonable 
one—that equal fraternal correlationsindicate the exist- 
ence of equal correlations between parents and children, 
we arrive at the conclusion that the resemblance 
between parents and their offspring is of much the 
same kind and amount in the case of mental as it is in 
the case of bodily characteristics. 
What we may perhaps describe as the main general- 
ization so far arrived at by biometricians is known 
as the Law of Ancestral Heredity. This hypothesis 
supposes, or at least in its original form supposed, that 
