46 



Colour Inheritance in Horses 



was, then the whole family works out exactly according to expectation. 

 The produce from one gray parent and one not gray is as follows : 



Total 



400 



428- 



Of the 428 — foals neither gray nor chestnut 38, plus an unknown 

 number of the Percherons, are blacks. This gives a clue as to whether 

 or not the bay factor is necessar}^ before G can cause gray. If it is, 

 then these 38+ blacks should be eliminated from the table, and the 

 result would be 400 grays to 390 — bays and browns, or, leaving out 

 all Percherons, 369 grays to 361 bays and browns. Now gray is an 

 unpopular colour, and it seems very unlikely that as large a proportion 

 of the gray foals would be recorded as of the other colours, and I should 

 therefore expect fewer grays than the calculation calls for, rather than 

 more. For this reason, and because no black has yet been found io 

 carry the G factor, I believe that G can cause gray in the absence of 

 B, though this is by no means proven as yet. 



Grays to grays give the expected 3 to 1 ratio. 



Just what this G factor is is a rather difficult question. Gray 

 differs from the colours hypostatic to it both in the posses.sion of white 

 hairs, and in the mottled or dappled pattern. Now this dappled 

 pattern, or one very similar to it, is to be seen also on chestnuts, bays, 

 browns, duns, and sometimes even blacks. In the case of browns, the 

 spot inside may be lighter than the ring around it, that is it may have 

 more brown hairs, or this condition may be just reversed. If there is 

 a separate dappling factor, then gray \vould not act like an ordinary 

 colour due to a single factor, but would be produced by non-gray 

 parents, unless the dappling factor is present in most horses. Many 



