A. H. Sturtbvant 51 



However, his sire is one of the dark-eyed somewhat spotted whites, his 

 dam being a brown Trotter. Since "glass" eyes occur not infrequently 

 in pigmented horses it seems probable that this white-eyed albino (?) is 

 really an extreme case of spotting, plus an entirely independent "glass" 

 eye. Mr Newell writes that white mated to white gives about 50 % 

 white to 50°/„ pigmented. He reports only three matings of white to 

 white. The results of these were, one white, one roan, and one gray. 

 Apparently, then, the white factor stands at the very top of the series. 

 However, I am not sure that this is the whole story, as it would be a 

 peculiar coincidence if it were a mere accident that the only two non- 

 whites produced from white by white are representatives of the only 

 two other colours having white in the coat, and these both such un- 

 common colours. On the other hand, it does not appear that white by 

 pigmented gives a. lai'ge percentage of grays and roans. 



In addition to those already mentioned I wish to extend my thanks 

 to the following horsemen, who have supplied me with information used 

 in this paper: Messrs S. J. Fleming, W. B. Wallace, D. W. Northrop, 

 T. Sterneman, and G. M. Garth. 



Summary. 



It seems probable that chestnut always breeds true. Therefore the 

 placing of C (chestnut or yellow) at the bottom of the scale probably 

 represents the condition of nearly all breeds of horses. Epistatic to it 

 is H (black). Next comes, in the breeds studied, B (baj' or brown), 

 epistatic to both the preceding. G (gray) is next higher. Next is 

 R (roan), which is probably always evident when present' and which 

 probably merely causes a sprinkling of white hairs, without otherwise 

 affecting the colour. Finally, we have W (white). 



' Unless suppressed by the next factor, TV. 



4—2 



