Mar. 20 ,1916 
Inheritance of Fertility in Swine 
1151 
Table I .—Deviation in size of litters in swine 
Generation. 
Number of 
litters. 
Mean. 
Standard devia¬ 
tion. 
Coefficient of 
variability. 
P. 
1,770 
885 
885 
7.84±a 3494 
7.82 ± . 4897 
7 - 9 i± -4965 
2. l8±o. 2461 
2. i6± • 3462 
2. ig± . 3511 
27. 80 
27. 60 
27. 55 
F x . 
f 2 . 
The mean litter size is quite constant from generation to generation, 
and furthermore quite close to that obtained by Surface (26) for the 
breed in general. If anything of Mendelism is involved here, it is not 
revealed by this method of treatment, for the standard deviation is so 
nearly the same for each of the generations involved as tfc give no hint 
of segregation. In fact, the coefficients of variability would indicate a 
slowly increasing degree of homozygosis. 
Two interpretations may be placed on these figures. The animals 
studied are either practically constant from a zygotic standpoint, and 
the variations in litter size are due to environmental treatment, or else 
there is so much heterozygosis present in the grandparents that the 
parents are as much F 2 as F t in hereditary make-up. For the present 
the writers are going to use the latter interpretation, as there is no 
evidence at hand to support a belief in the former. 
Table II .—Deviation in litter size of the offspring from the parental generation in swine 
BOAR I 
Size of litter of 
parents. 
Num¬ 
Fi generation. 
F* generation. 
ber of 
mat¬ 
Boar. 
Sow. 
ings. 
Mean. 
Standard devia¬ 
tion. 
Mean. 
Standard devia¬ 
tion. 
I 
9 
I 
5 
O 
9 
O 
I 
4 
I 
2 
0 
9 
O 
BOAR 2 
2 
5 
1 
4 
0 
6 
0 
2 
6 
2 
8 ±1.43 
3 ±1.0117 
7-5 ±o -239 
.5 ±0. 1686 
2 
8 
2 
6. s ± . 717 
i- 5 ± • x 737 
4 ± -479 
1 ± .3372 
2 
9 
1 
6 
0 
6 
0 
BOAR 3 
3 
4 
3 
7 ±0. 171 
1. 41 ±0. 3433 
9 ±1.704 
4 - 3 2 ± i * x 94 
3 
6 
2 
< 5 . 5 ± • 239 
.5 ± . 1686 
8 ± .95 
2 ± .674 
3 
7 
4 
7. 25± 1. 6218 
4. 8 ± 1. 1502 
7. 75± .8869 
2.63d: .627 
3 
11 
1 
6 
0 
8 
0 
3 
10 
2 
10 ± .95 
2 ± . 674 
11 
0 
3 
14 
1 
11 
0 
6 
6 
