INHERITANCE OF COLOR IN PERCH KRON HORSES. 2/1 



About 75 per cent, of the parents of grays are gray while 

 only 60 per cent, of the parents of black individuals are black. 

 This was found to be the case with the parents of 300 grays and 

 300 blacks selected at random from data not included in the rest 

 of this paper. Thus the reason for the prepotency of gray is 

 manifest from the average character of its ancestry. 



The prepotency of the dam seems to be partly explained by the 

 fact that gray dams are most numerous, but this does not wholly 

 explain the dam's prepotency. For gray dams are prepotent in 

 a higher degree than are gray sires (56:51 for colts ; 55:50 for 

 fillies). 



It must be remembered that we are dealing with the recorded 

 colors as yearlings and that a certain per cent, of color changes 

 must occur later on. It would be interesting, for example, to 

 have data bearing upon the question whether the young of both 

 sexes tend to resemble the dam. 



Pearson ('01) finds in respect to the inheritance of eye- color 

 in man, " That the younger generation takes as a whole more 

 after its male than its female ascendents and collaterals." In 

 this paper the prepotency of the dam has been shown to be 

 partly the result of association with a prepotent color, but this 

 factor does not wholly explain the dam's prepotency although it 

 diminishes her apparent prepotency. 



The conclusion that the prepotency of the gray color is the 

 effect of inbreeding owing to its long established existence as a 

 racial characteristic in this breed may suggest the question as to 

 how long would be required for the black color to become fixed 

 by long continued selection and inbreeding. There may be 

 some evidence as to the point in the data contained in Table 

 XV. (see Appendix). Of the 91 black offspring 38 had both 

 parents and at least half of the grandparents and great grand- 

 parents black. Moreover all the individuals having that amount 

 of black in their ancestry were black. Of course this apparent 

 result must be largely caused by breeders' selection, eliminating 

 grays from the records. If it has any force at all as an exhibi- 

 tion of the effects of the cumulation of black in the near ancestry 

 it would go to show that the selected color tends to become 

 stamped in "indelibly" so to speak after a few generations of 

 selective inbreeding. Any such facts, if proved, would of course 



