288 
PROFESSOR KARL PEARSON AND MISS ALICE LEE, 
duration of the son’s marriage, and since there is a longer period for the possible 
exhaustion of the male fertility, we find is slightly larger. Although the numbers 
are smaller than in Case (i.), the probable error is not so large but that we can still 
assert an inheritance of fertility in man. 
(iv.) Lastly, to compare with Case (iii.) for women, 1000 cases were extracted 
from the Landed Gentry, and are given in Table VIL Here no marriage of the son 
or parents was taken under a minimum of 15 yeai's’ duration, and only one son 
taken from each family. We found : 
M, = 5-304, = 6-272, 
cr, = 2'95], o-p = 2-911, 
= -iifii. 
Thus the longer duration of the marriage, which gives a greater chance for the 
exhaustion of the fertility of a partially sterile father, leads to an increased corre¬ 
lation. The probable error here is -0210, and the correlation is thus unquestionable. 
It would be idle to apply the theory before developed to these male cases, for the 
simple reason that we must certainly look upon them as containing a large proportion 
of uncorrelated material. But they suffice to show that male fertility is an inherited 
character, and although the results are widely different from those indicated by the 
law of ancestral heredity, they are large when we consider how little male fertility 
appears measurable by the results of monogarnic marriage. Were an approximately 
close measure of male fertility available, there is certainly in the above results no 
reason to induce us to believe that it would not be found to obey the law of ancestral 
heredity. 
4 
(11.) 0)1 the Inheritance of Fertility in Woman through the Male Line. 
Although we are not able to measure the potential fertility of the male, we are 
able to determine whether he transfers fertility from his mother to his daughter. 
This may be simply done l)y correlating the fertility of a woman and that of her 
paternal grandmother. This problem belongs to an important class—namelv, 
questions as to the extent to which a sexual character is inherited through the 
opposite sex. Darwin has touched upon this “ transmission without development ” in 
Chapter viii. of the ‘ Descent of Man,’* and we shall find his views amply verified. 
The problem before us is : Does a woman have as close correlation with her paternal 
as with her maternal grandmother in the matter of fertility ? 
To solve this problem 1000 cases were taken out of the Peerage for the fertility of 
a woman and of her paternal grandmother. The marriages of the woman and of her 
grandmother were botn taken with a minimum duration of fifteen years. Every care 
was taken that no weight should be given to fertile families bv taking only one out 
* Second Edition, p. 227, ‘ Laws of Iqheritance,’ 
