132 THE ORIGIN OF SPECIES 



nine out of ten mules have striped legs. I once saw a mule with 

 its legs so much striped that any one might have thought that it 

 was a hybrid zebra; and Mr. W. C. Martin, in his excellent treatise 

 on the horse, has given a figure of a similar mule. In four colored 

 drawings, which I have seen, of hybrids between the ass and zebra, 

 the legs were much more plainly barred than the rest of the body; 

 and in one of them there was a double shoulder-stripe. In Lord 

 Morton's famous hybrid, from a chestnut mare and male quagga, 

 the hybrid and even the pure offspring subsequently produced 

 from the same mare by a black Arabian sire, were much more 

 plainly barred across the legs than is even the pure quagga. Lastly, 

 and this is another most remarkable case, a hybrid has been 

 figured by Dr. Gray (and he informs me that he knows of a sec- 

 ond case) from the ass and the hemionus; and this hybrid, though 

 the ass only occasionally has stripes on his legs and the hemionus 

 has none and has not even a shoulder-stripe, nevertheless had all 

 four legs barred, and had three short shoulder-stripes, like those 

 on the dun Devonshire and Welsh ponies, and even had some 

 zebra-like stripes on the sides of its face. With respect to this last 

 fact, I was so convinced that not even a stripe of color appears 

 from what is commonly called chance, that I was led solely from 

 the occurrence of the face-stripes on this hybrid from the ass 

 and hemionus to ask Colonel Poole whether such face-stripes ever 

 occurred in the eminently striped Kattywar breed of horses, and 

 was, as we have seen, answered in the affirmative. 



What now are we to say to these several facts? We see several 

 distinct species of the horse genus becoming, by simple variation, 

 striped on the legs Jike a zebra, or striped on the shoulders like an 

 ass. In the horse we see this tendency strong whenever a dun 

 tint appears — a tint which approaches to that of the general color- 

 ing of the other species of the genus. The appearance of the 

 stripes is not accompanied by any change of form, or by any other 

 new character. We see this tendency to become striped most 

 strongly displayed in hybrids from between several of the most 

 distinct species. Now observe the case of the several breeds of 

 pigeons: they are descended from a pigeon (including two or 

 three sub-species or geographical races) of a bluish color, with 

 certain bars and other marks; and when any breed assumes by 

 simple variation a bluish tint, these bars and other marks in- 

 variably reappear; but without any other change of form or 

 character. When the oldest and truest breeds of various colors 

 are crossed, we see a strong tendency for the blue tint and bars 

 and marks to reappear in the m©ngrels. I have stated that the 



