MENDELISM IN DOMESTIC ANIMALS 469 
indistinctly striped. Indistinct striping and other types of marking 
occasionally occur in horses, but the hereditary relations concerned in 
their appearance are not well understood. 
J. Wilson has advanced a formulation which is fundamentally different 
from the one which has been outlined above. He assumes that gray, dun, 
bay, black, and chestnut form a series of polygamous factors as he calls 
them, multiple allelomorphs according to our terminology, in which each 
go g” q’ g? G 
Gg Gg" Gq? Gg? GG 
G Gray Gray Gray | Gray Gray 
3 gray: 1 chestnut! 3 gray: 1 black | 3 gray : 1 bay | 3 gray: 1 dun | All gray 
| i 
gg | g2gh | g’g? | gge 
g4 Dun Dun Dun Dun 
3 dun: 1 chestnut | 3 dun:1 black | 3 dun: 1 bay | All dun 
gy pg" Gi 
a Bay | Bay Bay 
3 bay: 1 chestnut 3 bay: 1 black | All bay 
ghg? grgh 
g" Black Black 
3 black : 1 chestnut All black 
gg" 
g Chestnut 
All chestnut 
Fig. 187.—The genotypes of gray, dun, bay, black, and chestnut coat colors in the 
horse according to the formulation of Wilson. The way in which animals of a particular 
genotype behave in a subsequent generation when mated together is shown in each square. 
member of the series in the order named is dominant to succeeding 
members and recessive to the preceding ones. In Fig. 187 we have out- 
lined the possible combinations which could occur within such a series of 
multiple allelomorphs, and the consequences of such combinations. In 
addition to this pentuple series of multiple allelomorphs, Wilson assumes 
that there is an independent dominant roan factor for the roan pattern, 
and that there are modifying factors which affect the shade and distribu- 
tion of pigment. Brown he considers a modified bay. Although this 
formulation is undeniably simpler than the one which was discussed first, 
it is highly probable that this simplicity is very misleading. The series 
of colors evidently does not well conform to the general rule of multiple 
allelomorphism of exhibiting a graded series with a diminishing in- 
tensity; but, so far as the stud book records of Table LXI are concerned, 
about the only place where this formulation fails to meet all the ob- 
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