44 Colour Inheritance in Horses 



of bay and brown remain to be settled ; and although there is evidence 

 in favour of brown being dominant to bay, this conclusion is not clearly 

 established. It must be remembered these are the colours breeders 

 have the greatest difficulty in discriminating; and errors affect sires 

 and dams and foals. In regard to sires it has been possible to correct 

 the registered colours in several cases ; and while every correction has 

 increased the evidence in favour of brown being dominant, it is still 

 possible that there may be other explanations, as, for instance, that bay 

 is a diluted brown." 



I shall first give the figures bearing on this question, and then 

 discuss their significance in connection with the two views given above. 



My hypothesis that brown is a heterozygous colour was based upon 

 two facts. In the first place, I am unable to see any very sharp line 

 between bay and brown. "Wilson evidently thinks the two colours are 

 distinct, but I can find no definite statement as to what the difference 

 is, although he discusses the distinction between the various colours at 

 some length. Secondly, all the browns from which I could find any 

 fair number of foals produced some blacks, with the exception of the 

 stallion Prodigal, which, as I have explained above, now turns out to 

 be a bay. I have found 15 such brown sires producing black foals. 

 In Wilson's tables appear five brown and one doubtful bay or brown 

 Clydesdale sires, all of which have a fair number of black foals. There 

 are also five brown Thoroughbreds. Two of these sired no blacks 

 among 93 and 95 foals, respectively, though each has a foal recorded 

 as "brown or black." Ladas has one black and one black or brown 

 among 97 foals, Desmond three black and two brown or black among 

 48 foals, and Wolf's Crag seven black and one brown or black 

 among 95 foals. Here we meet an interesting fact — the extreme 

 scarcity of blacks among English Thoroughbreds. Wilson believes 

 that most, if not all, the recorded blacks are really browns, and was 

 not able to find a genuine black stallion. The Desmond mentioned 

 above is recorded as a black, but Wilson ascertained that he is really 

 a dark brown, and the same was found to be true of all the mares 

 recorded as black of which he could get definite and reliable informa- 

 tion. Only about 1 "/„ of these Thoroughbreds are recorded as blacks. 

 Of course by my hypothesis it would be hard to explain how there 

 could be about ] 4 °l^ browns and only 1 °/„ blacks. However, I shall 

 not try to explain this, as the hypothesis is pretty well disproved by 

 the result of mating browns together. If it were correct such matings 

 should produce 25 °/^ blacks, 25 °/^ bays, and 50 "/^ bays and browns. 



