HYBRIDIZATION IN ANIMAL BREEDING 517 
nevertheless a brief mention of a few considerations which tend to cloud 
the issue cannot be held out of place. The mule at its best, when com- 
pared with the beauty of form of a well-bred horse, suffers greatly. It 
partakes too much of the characters of the ass, ancient symbol of all 
that is silly and ugly, to excite greatly the admiration of those who have 
sentimental regard for the horse, the close companion of man in battle, 
foray, and chase. A second consideration is the fact, also true in cross- 
- breeding, that the breeding of mules withdraws permanently from .the 
racial stream much of the very best of horse blood. While inferior mares 
Fic. 198.—A hinny, obtained by mating a jennet to a stallion. (After Mumford.) 
may produce mule colts that are better for draft purposes than any horse 
colts they might produce, nevertheless for the production of the best class 
- of mules, it is absolutely necessary to select with care the very best type 
of brood mares. For these reasons, and others of less importance, 
strong partisans of the horse are prone to permit their prejudice against 
the mule and their high regard for the horse to influence strongly their 
judgment of the point at issue, namely this, whether a given lot of 
mares when bred to a good jack will produce mules which are better 
suited for draft purposes than would be the horse colts produced by these 
mares when bred to an equally good stallion. 
By common consent the mule is considered more vigorous, hardier, 
and freer from disease than either parent. Part of these qualities may 
be ascribed to the ass’s influence, but certainly these are characters 
common to a large number of species hybrids. The reciprocal cross, 
jennet X stallion, the hinny, is commonly reported to be different from 
the mule. According to Darwin, the male is prepotent in both crosses 
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