570 
Journal of Agricultural Research 
Vol. XXIII, No. 7 
spotting may not be apparent in all individuals carrying it because the 
spots may all happen to be covered epistatically with black pigment. 
The third form of bicolor appears as a red with a sandy or white belly 
(PI. 2, D), or a sandy with a white belly. Black may or may not be 
present, but the occurrence, or at least the observance, of this character 
is more frequent with the nonblacks. Both the bicolor reds occurring 
in the back-cross and all three of the bicolor reds in the generation 
were of this type. The line of demarcation between the two colors 
may be sharp or they may blend into each other. This type of color— 
that is, a lighter underline than sides or back—is common to most mam¬ 
mals as an integral part of the agouti pattern. It is striking in the young 
of the wild hog, which also exhibit both (if they are genetically separate) 
the agouti and the striping patterns. For reasons to be discussed later 
it is considered probable that the three characters of lighter underline, 
Striping pattern, and adult agouti pattern are due either to identical or 
to closely similar factor complexes. 
A most interesting peculiarity of the F 2 Berkshire-Duroc generation 
was that two of its individuals, which were otherwise a light sandy with 
white bellies, distinctly showed longitudinal stripes of a pattern similar 
to that of the young of the wild hog, but not nearly so intensely colored 
and hence not so contrasted. They were also not so permanent and 
disappeared within a very few weeks after birth. In the founding of 
the Sapphire breed, according to McEean (7), the striping pattern 
appeared several times, and the stripes in some individuals persisted 
throughout life. Simpson also reports (13, 11) the appearance of striped 
individuals in crossing several breeds, of which he mentions specifically 
a Tamworth by Yorkshire cross and a Berkshire by Poland-China cross. 
This striping pattern as seen in a hog of unknown ancestry found on 
a farm in Wisconsin is shown in Plate 2, E. Considering everything, 
this phenomenon of the striping pattern in pigs is quite comparable with 
the appearance of barring on pigeon wings when distinct breeds are 
crossed and with the dorsal and shoulder stripes sometimes seen on 
mongrel dun-colored horses, phenomena which have been discussed since 
Darwin’s time. 
There was one litter of pigs of the F 3 generation which threw some light 
on this question in an unexpected manner. A white F 2 sow (which had, 
however, patches of black pigment in her skin although the hair growing 
out of these patches was quite white) when mated with an F 2 boar 
(PI. 2, F) which was red with a sandy belly produced the litter of 11 
pigs shown in Plate 2,G. All were some shade of sandy or red, but also 
all had light bellies and all were striped even more distinctly than either 
of the F 2 Berkshire by Duroc striped pigs. None of them showed .any 
trace of a skin spot of black pigment. Four were classified as dark red, 
5 were light red, 1 was a sandy red, and 1 was a very light sandy, almost 
white. The red pigment on the dark red ones was more of a brown 
than on any F 2 individual and their stripes were very distinct. Neither 
parent was observed to be striped and only the sire exhibited the lighter 
belly, but it is conceivable that the dam possessed the factors for both 
(if they are two) patterns, but did not have enough pigment in her hair 
for the expression of either. Although a complete factorial analysis 
has not yet been achieved, this much is certain; the striping pattern 
and the lighter underline are closely related and the factors which pro¬ 
duce them are relatively few and simple in the mode of their expression, 
else such a combination would not have appeared uniformly in such a 
