2l6 A. H. STURTEVANT. 



nut roans there should be no chestnuts carrying the roan factor). 

 With one possible exception in the case of each color I have found 

 no such case. How unsatisfactory these two cases are will 

 appear from the color pedigrees of the horses concerned. 



( Banker Rothschild, f Rothschild. 



brown. { Pilot Anna, gray. 



i Lady Forrester, ] Royal George, chestnut. 



chestnut. \ Belle of Saratoga, brown. 



f Young Clay Pilot. / Clay Pilot, bay. 



North Wind, roan. bay , R Executorf brown . 



I Lola M., chestnut. { Ljght ^ chestnut< 



SUMMARY. 



This study of the pedigrees of blooded trotters indicates that 

 the color of such horses is usually controlled by five factors, as 

 follows. First, a factor for chestnut, C, present in all the horses 

 studied. Second, a factor for black, Hurst's factor, H, epistatic 

 to the factor C, and hypostatic to the three following. Third, 

 a factor for bay, B. Fourth, a factor for roan, R. Fifth, a 

 factor for gray, G. R or G inhibits B if it is present, but whether 

 they depend upon its presence for their own appearance or not 

 is not clear. 



COLUMBIA UNIVERSITY, 

 June, 1910. 



