Wilson — Polygamous 3fendeUan Factors. 



Colours of dams 



307 



In the one case in which the discrepancies are serious, that namely in 

 which 16 black foals are recorded as the progeny of chestnut mares and brown 

 horses containing recessive chestnut, five of the sixteen are the progeny of a 

 sire which was so very dark brown that he was frequently spoken of as black, 

 and there can be very little doubt that these five foals were the colour of tlieir 

 sire. 



But what of the three remaining colours, cream, dun, and grey ? Are 

 they also the result of single factors which are polygamous ? It is scarcely 

 conceivable they could be anything else, for if they were, a factor or factors 

 in any of them would find no factor to pair with when these colours were 

 mated with brown, black, or chestnut. It can be shown, however, that the 

 six colours : chestnut, black, brown, cream, dun, and grey are each the 

 result of single polygamous factors, and that they form a series in which 

 each can mate with any of the others and each, taken in the order above, is 

 recessive to all set down to its right. 



If they do form such a series, tlien, since no colour can be impure for more 

 than one other colour at a time, it should follow that : — 



(1) No colour should produce any other colour than itself and its recessives 

 unless mated with a colour which is its dominant. 



(2) When a colour whicli is impure is mated with th-e colours lower in the 

 scale of dominance than itself it should produce itself on the one hand and an 

 equal number of 2l\\ the other lower colours together on the other. Impure 

 greys, for instance, should produce greys on the one hand and an equal 

 mimher of all the other colours together on the other. For the grey factor 

 must be carried off by half the progeny, and tlie recessive factor, whatever it 

 may be, by the other half, and the non-grey colours will be of various kinds, 

 depending upon the factors with which the recessive combines. 



(3) An impure colour should produce no colour lower in the scale than 



