Chap. XIII. 



REVERSION. 



43 



or leg stripes ; but traces of these latter stripes may occasionally be seen 

 even in the adult; 36 and Colonel S. Poole, who has had ample oppor- 

 tunities for observation, informs me that in the foal, when first born, the 

 head and legs are often striped, but the shoulder-stripe is not so distinct 

 as in the domestic ass ; all these stripes, excepting that along the spine, 

 soon disappear. Now a hybrid, raised at Knowsley 37 from a female of 

 this species by a male domestic ass, had all four legs transversely and con- 

 spicuously striped, had three short stripes on each shoulder, and had 

 even some zebra-like stripes on its face ! Dr. Gray informs me that he 

 has seen a second hybrid of the same parentage similarly striped. 



From these facts we see that the crossing of the several equine 

 species tends in a marked manner to cause stripes to appear 

 on various parts of the body, especially on the legs. As we do 

 not know whether the primordial parent of the genus was 

 striped, the appearance of the stripes can only hypothetically 

 be attributed to reversion. But most persons, after considering 

 the many undoubted cases of variously coloured marks re- 

 appearing by reversion in crossed pigeons, fowls, ducks, &c, will 

 come to the same conclusion with respect to the horse-genus; 

 and in this case we must admit that the progenitor of the group 

 was striped on the legs, shoulders, face, and probably over the 

 whole body, like a zebra. If we reject this view, the frequent 

 and almost regular appearance of stripes 'in the several fore- 

 going hybrids is left without any explanation. 



It would appear that with crossed animals a similar tendency 

 to the recovery of lost characters holds good even with instincts. 

 There are some breeds of fowls which are called " everlasting 

 layers," because they have lost the instinct of incubation ; and 

 so rare is it for them to incubate that I have seen notices pub- 

 lished in works on poultry, when hens of such breeds have 

 taken to sit. 38 Yet the aboriginal species was of course a good 

 incubator; for with birds in a state of nature hardly any 



35 Another species of wild ass, the 

 true A. hemionus or Kiang, which 

 ordinarily has no shoulder-stripes, is 

 said occasionally to have them; and 

 these, as with the horse and ass, are 

 sometimes double : see Mr. Blyth, in 

 the paper just quoted, and in 'Indian 

 Sporting Review,' 1856, p. 320; and 



Col. Hamilton Smith, in ' Nat. Library, 

 Horses,' p. 318 ; and 'Diet. Class. d'Hist. 

 Nat.,' torn. iii. p. 563. 



37 Figured in the ' Gleanings from the 

 Knowsley Menageries,' by Dr. J. E.Gray. 



38 Cases of both Spanish and Polish 

 hens sitting are given in the ' Poultry 

 Chronicle,' 1855, vol. iii. p. 477. 



