Appendix 201 



Gen. D. These selected horses in their turn are 

 sons of sires averaging about ten years of age, 

 but they come from only about 450 of the original 

 1 1 00 selected in Gen. B. When we examine the 

 remaining 450 in Gen. B. we find that they were 

 sons of horses in Gen. A which averaged about 

 thirteen years of age at the time these particular 

 sons were born. The breeders, in selecting from 

 Gen. C, eliminated from Gen. B. principally 

 horses which were sons of young sires in Gen. A. 

 Cutting down the lines of descent in Gen. B 

 from 1 100 to 450 made a further elimination in 

 Gen. A, so that when the selection is made in 

 Gen. C descent runs back in male line to not 

 more than about two hundred horses in Gen. A. 

 When we examine this remaining two hundred 

 in Gen. A we find that they are sons of horses 

 averaging about fourteen years of age, which 

 means that there has been a further elimination 

 of sons of young sires in Gen. A. 



When the breeders select from Gen. D those 

 horses which they intend to use to produce Gen. 

 E, they take sons of horses averaging about ten 

 years of age, but in doing so they eliminate part 

 of their previous selection in Gen. C, which in 

 turn eliminates more from Gen. B, and this in 

 its turn eliminates more from Gen. A. Each one 

 of these eliminations bears more heavily on the 

 sons of young sires than it does on the sons of old 

 sires, the result of which is seen in the fact that 



