COLOR INHERITANCE IN THE HORSE. 
BY EDWARD N. WENTWORTH. 
While laboratory animals have yielded very nicely to the study of 
their inheritance of color, the horse still remains a mystery in many of 
the phases of coat transmission. Hnrst and Bunsow have recognized 
chestnut with the sorrel and liver shades as a true recessive, and Hurst 
has shown black to be epistatic to this reddish pigment. Bays and browns 
have been with difficulty separated but have been considered as epistatic 
to both colors mentioned, while grays and roans seem dominant to the 
entire series of color. One difficulty which seems to have beset all in- 
vestigators up to the present time, with the exception of Dr. Walther, 
is the tendency to arrange all colors as an epistatic and hypostatic series, 
expecting them, then, to conform to the simple laws of presence and 
absence. That this attempt has been a real stumbling block the writer 
hopes to show, by means of his arrangement of factors in a manner 
slightly similar to Walther ’s and Sturtevant’s methods but differing in 
the factors themselves. 
THE PIGMENTS IN THE EQUINE COAT. 
A microscopic examination and simple chemical tests reveal only two 
pigments in the coat of the ordinary horse. These seem to correspond 
to the red or yellow and the black pigments found in rodents. There 
is quite evidently a lack of chocolate or else such a close linkage of the 
brown and black pigments that they are not readily separable. 
Under both the low and high power red pigment granules may be 
discerned in the sorrel, chestnut, bay or red roan hairs. The granules 
are sharply distinct and typical in form but there seems also to be a 
diffuse red, slightly lighter in tinge, distributed quite evenly throughout 
the cortical layer. This is entirely separate from the effects of spherical 
aberration, and is quite evidently a basal ground pigment found in all 
but white or albino hairs. 
Black pigment granules rather larger, coarser and more frequently 
clustered appear in the black horse. They are so numerous and typical 
that they quite obscure the red ground pigment. 
