HYBRIDS AND MONGRELS COMPARED 329 



resemble each other closely ; and so it is with mongrel plants 

 from a reciprocal cross. Both hybrids and mongrels can be 

 reduced to either pure parent-form, by repeated crosses in 

 successive generations with either parent. 



These several remarks are apparently applicable to ani- 

 mals; but the subject is here much complicated, partly owing 

 to the existence of secondary sexual characters; but more 

 especially owing to prepotency in transmitting likeness run- 

 ning more strongly in one sex than in the other, both when 

 one species is crossed with another, and when one variety is 

 crossed with another variety. For instance, I think those 

 authors are right who maintain that the ass has a prepo- 

 tent power over the horse, so that both the mule and the 

 hinny resemble more closely the ass than the horse ; 

 but that the prepotency runs more strongly in the male 

 than in the female ass, so that the mule, which is the 

 offspring of the male ass and mare, is more like an ass, 

 than is the hinny, which is the offspring of the female 

 ass and stallion. 



Much stress has been laid by some authors on the sup- 

 posed fact, that it is only with mongrels that the offspring 

 are not intermediate in character, but closely resemble one 

 of their parents ; but this does sometimes occur with hy- 

 brids, yet I grant much less frequently than with mongrels. 

 Looking to the cases which I have collected of cross-bred 

 animals closely resembling one parent, the resemblances 

 seem chiefly confined to characters almost monstrous in their 

 nature, and which have suddenly appeared — such as albinism, 

 melanism, deficiency of tail or horns, or additional fingers 

 and toes; and do not relate to characters which have been 

 slowly acquired through selection. A tendency to sudden 

 reversions to the perfect character of either parent would, 

 also, be much more likely to occur with mongrels, which are 

 descended from varieties often suddenly produced and semi- 

 monstrous in character, than with hybrids, which are de- 

 scended from species slowly and naturally produced. On the 

 whole, I entirely agree with Dr. Prosper Lucas, who. after 

 arranging an enormous body of facts with respect to animals, 

 comes to the conclusion that the laws of resemblance of the 

 child to its parents are the same, whether the two parents 



