Wilson — The Inheritance of the Dun Coat- Colour in Horses. 195 



gamete, bay must be recessive to dun. Accordingly, bay, being recessive to 

 dun, must also be recessive to chestnut, which, as we know, is absurd. Our 

 assumption witli regard to Silverlocks needs revision therefore ; and we can 

 only suggest either that she was dun or some colour containing dun, or that 

 she was not the dam of the Grodolpliin Arabian's three dun foals. 



But there is no need to adopt tliis kind of argument, for tlie homozygous 

 bay Godolphin Arabian's three dun foals are sufficient proof that dun is 

 dominant to bay. Bach of them must have carried a bay gamete from their 

 sire, which was hidden by dun, and, therefore, recessive to it. 



The relative positions of duu and chestnut can also be made out from the 

 table. But there is really no need to do tliis; for, since chestnut is recessive to 

 bay, and bay to dun, therefore chestnut is a fortiori recessive to dun. The 

 table may be used in confirmation. Brilliant (0 3), the best-known dun of 

 this Thoroughbred dun family, was the sou of Silverlocks' eldest dun daughter 

 and Crab, a very famous sire. Brilliant had a number of chestnut foals, and 

 this colour must have been included in his gametic composition, and is, there- 

 fore, recessive to dun. His dam, as we have just seen, was a heterozygous 

 dun, with bay recessive, while his sire was a heterozygous grey, with chestnut 

 recessive.' In him a dun gamete from his dam must have united with a 

 chestnut gamete from his sire ; for, had a dun gamete united with a grey, 

 Brilliant would have had a number of grey foals, but no chestnuts. 



The position of dun relatively to brown and black cannot be made out 

 from the table, because the colour of only one foal from a brown and dun 

 mating is given, and only two black foals appear in the table. Besides, 

 there is uncertainty as to whether brown and black were accurately dis- 

 tinguished from each other. Black, however, may be taken as recessive to 

 dun, since it was found to be recessive to bay in the previous paper. 



Nor can the relative positions of dun and grey be made out by an exami- 

 nation of the gametic composition of the animals concerned ; for, although 

 the duns in the table have grey foals only when mated with greys, the grey 

 gametes of the foals may all be associated, although this is unlikely, with 

 recessive bay and chestnut gametes from their dun parents. In any case, the 

 numbers are few. 



For evidence on this point we must go to the Polo and Riding Pony 

 Stud-book, in which we find the statistical argument suggested in the last 

 paragraph completely confirmed ; for, here again, and now over a considerable 

 number of cases, dun does not produce grey unless it be mated with that 

 colour. There are now eleven volumes of this stud-book published, in which 

 60 matings of dun with other colours than grey are recorded, and in no case 



' This has been found by working through Crab's progeny in the first volume of the slud-book. 



