Mar. so. 1916 
Inheritance of Fertility in Swine 
ii57 
Before these curves 
can be accepted as 
more than merely sug¬ 
gestive a further anal¬ 
ysis must be made. 
There is a significant 
deviation from ex¬ 
pectancy in the right- 
hand branch of the 
curve of the total pop¬ 
ulation, which persists 
even after the separa¬ 
tion into three curves. 
In figure 4 this defi¬ 
ciency is located in the 
left-hand branch of 
curve 3, but the minus 
deviations may just as 
logically belong in the 
right-hand branch of 
curve 2, suggesting 
that it also may be 
compounded of two 
curves dependent on a 
genetic factor not dis¬ 
closed thus far. 
Paralleling this 
study some actual 
matings of swine have 
been planned and are 
in progress. 
SUMMARY 
(1) Fertility in swine 
offers favorable mate¬ 
rial for the study of 
quantitative inheri¬ 
tance, because the 
units of deviation are 
discrete. 
(2) Biometric stud¬ 
ies of litter size with 
mother and daughter 
have indicated a small 
degree of inheritance. 
(3) Crosses of breeds 
having different mean 
