Xll GENERAL INTEODUCTION. 



iuterbreedingj and prepotency. Tlie reversion hypothesis 

 or dogma is an extremely fascinating one. It has long 

 interested breeders of all kinds, yet it is still shrouded 

 in mystery. It is commonly believed that a child some- 

 times, instead of taking after its father, closely resembles 

 its father's mother, or is the image of its own mother ; 

 but we are still a long way from accounting for such 

 phenomena. As is pointed out in the second paper, 

 some of the hybrids in make and disposition strongly 

 suggest their zebra sire, othei-s their respective dams ; 

 but even the most zebra-like in form are utterly unlike 

 their sire in their markings. It is not a matter of taking 

 after a grandparent, but after an ancestor in all proba- 

 bility thousands of generations removed, an ancestor 

 probably far more like the Somali than any of the Bur- 

 chell zebras. 



Closely connected with reversion is the question of 

 prepotency. It is generally assumed that an old species 

 or variety is prepotent over a more recent species or 

 variety. It is impossible to saj whether zebra hybrids 

 in their markings take after a remote zebiu ancestor, or 

 after an ancestor common to both zebras and horses, or 

 after a hypothetical mid-parent combining the characters 

 of the less remote ancestors of both zebras and horses. 

 There is, however, no difficulty in seeing that while some 

 zebra hybrids, apart from their stripes, closely resemble 

 the zebra parent, others take after their horse parent, 

 thus showing that the wild sire is not necessarily the 

 most prepotent. But even when the hybrids are dis- 

 tinctly horse-like they never repeat recently acquired 

 peculiarities, such as a blaze or short ears, high withers, 

 or a small head and long neck. 



It would not, e.g., judging from the results already 

 obtained, be possible to breed from a piebald mare a 

 hybrid showing patches of white ; even from a mare 

 that produced a piebald foal to a whole-coloured horse. 

 This, I think, is not because of the prepotency of the 

 wild sire, but because there is reversion at least in 

 the body colour towards the wild and never gaudily 



