76 Dynamic Evolution 



and the facts which will be given later. First, 

 there is the advantage one horse has over the 

 other in regard to the number of years in the 

 stud. This should ordinarily make the first 

 horse a sire of a much more numerous progeny 

 than the second horse. Second, the con- 

 siderable number of foals got by the first 

 horse while the second is on the track should 

 make the first a sire at a less average age 

 than the second. Third, the maxim of 

 breeders of "breed to the blood of the winner" 

 and not to the winner should give the first 

 horse an advantage over the second horse 

 in breeding operations after the second horse 

 had retired from the track. This is particu- 

 larly true of full brothers, or horses closely 

 related to each other in blood. The first 

 horse would ordinarily be patronized more 

 frequently and be provided with the better 

 class of mares. Fourth, the temporary loss 

 of fertility coming from the strain of racing 

 should reduce the actual number of progeny 

 got by the second horse provided his oppor- 

 tunities were equal to those of the first horse. 



