Wilson — The Inheritance of Coat Colour in Horses. 333 



It also became apparent that there was some possibility of separating the 

 bays and the browns ; and in all tables these are put in separate columns. 

 There was, however, considerable difSoulty about the roans, in regard to 

 which we started with no definite theory. Several were tried, but none was 

 found to answer. The one expected to fit best was that the roans were a 

 hybrid between grey and one or more of the other colours, but it had to be 

 given up. Eventually it was found that roans stand by themselves ; and, for 

 the present, they may be left out of consideration. We have thus five 

 colours left to deal with : chestnut, black, bay, brown and grey. 

 The dominance of one colour over another is shown by — 



(ff) the dominant mated with the recessive producing sometimes the 

 dominant sometimes the recessive ; 



{b) the recessive mated with itself producing always the recessive. 



For example, Mr. Hurst showed that bays mated with chestnuts produced 

 both bays and chestnuts, while chestnuts mated with chestniits produced 

 chestnuts only. 



According to this criterion our figures from the first four volumes of 

 the Shire stud-book indicate, although the numbers are small, that grey is 

 dominant to the other four colours, and that black, in addition to chestnut, 

 is also recessive to bay or brown. The relative positions of black and 

 chestnut on the one hand and of bay and brown on the other are not 

 clear. Black may be dominant to chestnut and brown to bay, but there 

 are discrepancies in both eases. 



MaTINGS in vols. I. TO IV. OF THE ShIEE StUD-BOOK. 



Another set of figures was collected, but this time foals of the more 

 eminent sires were taken. It was thought thus to include more valuable and 

 therefore more carefully registered animals. And the search was continued 



3h2 



