76 THE MENDEL JOURNAL 



sprinters breed true, and this irrespective of weight 

 of ancestry, for I need hardly point out that natural 

 selection by the racecourse test is against the sprinting 

 sire. If the pedigree of a sprinter be examined, it 

 will be found that the names of the males which 

 occur in the second and earlier parental generations 

 are those of horses which could stay at least a mile, 

 and usually a greater distance. 



The winning stock of these sprinting sires can go 

 fast. Their nerve axons and muscle fibres conduct 

 impulses readily. Co-ordination, which involves the 

 alternate contraction and relaxation of voluntary 

 muscles, and even parts of the same muscle, is as 

 perfect as in the stayer. They have good bone, well- 

 proportioned frames, and the capacity for making 

 acquirements, desirable and undesirable, is not 

 wanting. One essential feature, however, they lack, 

 and can never acquire. They have not the faculty 

 for storing up an excess of oxygen in their muscle 

 fibres. A signal proof of this lies in the fact that 

 inhalation of oxygen has very little effect in increasing 

 a non-stayer's distance, but it has a decided effect in 

 that direction if given to an intermediate, and still 

 more in the case of a stayer. It very frequently 

 happens, if an attempt be made to train and race a 

 sprinter over long courses, that he rapidly looses 

 muscle and becomes slow. This would appear to be 

 the practical outcome of his carrying a muscle 

 slightly deficient in proteins and glycogen, and 

 proportionately increased in muscle fats and 

 water. 



