568 
Journal of Agricultural Research 
Vos XXIII No, 7 
The most obvious color, and the one about which there is the least 
chance for mistake, 3 is the black, and since it gives an exact 3 to i ratio 
in F 2 generation with such a relatively large number of individuals and 
such a close approximation to a 1 to 1 ratio in the back-cross, it is rather 
clearly evident that the presence of black color, irrespective of whatever 
pattern it may assume, is due in this cross to a single dominant Men- 
delian factor received from the Berkshire. 
In a few cases it was rather difficult to distinguish accurately between 
red and sandy and between sandy and white, but, on the whole (PI. 2, C), 
these colors segregated distinctly, and in the case of certain combinations 
such as black-and-red or black-and-white there was never any question. 
This distinctness of color was most marked when the pigs were young 
because some became darker as they grew older while others became 
lighter. There were different shades of sandy and different shades of 
red, but these are not considered in detail in this discussion. 
The ratio of the pigs showing red to the number not showing any red 
is very suggestive of a 9 to 7 ratio in the F 2 generation, and the ratio in 
the back-cross seems to prove definitely that at least one dominant 
factor whose function is to produce red pigment, rather than sandy or 
white, is possessed by the Duroc-Jersey breed. 
From the ratios of sandy to nonsandy and white to nonwhite we get 
definite proof only that sandy is not a heterozygous red, since the sandy 
pigs are so much less numerous than the reds, and that white is not due 
simply to an absence of factors for black and red and sandy. 
The independence in inheritance of the black color and distribution of 
spotting with black make it possible to regard red or sandy (that is, the 
possession of red pigment) as the fundamental ground color of the hog. 
In order to get at the relation of red, sandy, and white, therefore, it 
may be permissible to examine them, disregarding whatever black may 
be shown on the bodies of the animals. If the black color is omitted 
from Table III, the result shown in Table V is obtained. 
Tabus V .—Distribution of red , white , and sandy colors in Berkshire-Duroc-Jersey F 2 
generation 
Color. 
Number 
in Fj. 
Number 
in the 
back-cross. 
Red. 
61 
33 
White. 
So 
Sandy. 
18 
Red-and-sandy. 
13 
13 
x 
Red-and-white. 
I 
Sandy-and-white. 
x o 
13 
Total. 
3 
I48 
0 -5 
Let us first consider the relation of red and sandy. Omitting white on 
the theory that it is due to superimposed spotting factors, there are 87 
reds (61 red, 13 red-and-white, and 13 red-and-sandy) to 31 sandy (18 
sandy and 13 sandy-and-white). This misses a true 3 to 1 ratio (88^ 
to 29X) very slightly and suggests a single intensity factor difference 
6 Three of the pigs of the back-cross were classified as black-and-red although they possessed only one 
small black spot each, and in one of these cases the black was in the skin only and not in the hair growing 
on it. If either of these three cases has been placed in the wrong genetic classification, the correct ratio in 
the back-cross would still more closely approximate i to i. 
