Color inheritance in the Horse. 



By E. N. Wentworth, Ames Iowa, U. S. A. 

 (Eingegangen: 15. Mai 19 13.) 



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. Hurst 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 investigators 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 foimd 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. 



