54 THE MENDEL JOURNAL 



Sex Limitation in Staying Powers : Horses 

 V. Mares. 



As already stated, the sexes are foaled approxi- 

 mately in equal numbers. There is also but little 

 difference between the number of colts and fillies 

 which win at two years of age. Thus the winning 

 two-year-olds sired by the stallions set forth in the 

 table are made up of 980 colts and 1,050 fillies. But 

 in the whole of the winning stock of three years and 

 upwards by the same stallions the sexes are far from 

 being equally represented. 



It may be urged that the falling off in the number 

 of mares which win after two years of age is the direct 

 result of a corresponding decrease in the number of 

 mares which start at three years old and upwards. 

 To argue thus, however, would merely be to confuse 

 cause and effect ; for it must be remembered that the 

 trial ground, as well as the racecourse, is selective. 

 Owners, quite naturally, do not desire to pay training 

 expenses, entrance and jockeys' fees for mares or 

 fillies which, through lack of stamina, are unlikely 

 to win races. Were the number of races won by each 

 individual the subject of inquiry, the disparity in the 

 numbers of horses and mares which start after two 

 years might have to be taken into account. But this 

 is beside the point, for in the foregoing stamina 

 tables a winner of one race after two years has the 

 same numerical representation as a winner of eight 

 or a dozen races. Actually it is found that two-year- 

 old colts and fillies start in equal numbers, but that 

 after two years of age the horses which start out- 



