98 THE MENDEL JOURNAL 



is the difference in the physiological energy and 

 endurance between the red and pale varieties of 

 muscle fibre. Mr. Robertson has explained that the 

 red fibre in racehorses has a greater staying power 

 than the pale on account of its innate capacity to 

 store up within its own substance a greater reserve 

 of oxygen. But from the social aspect of the matter, 

 in which I am now chiefly concerned, this fact is 

 valuable as emphasizing that inherent physiological 

 differences do exist between different sorts of muscle 

 fibres. We may take two horses which in form 

 and other external attributes appear very similar, 

 but yet their performances will be very dissimilar. 

 And that dissimilarity is due to inherent causes. 

 No amount of environmental influence, in the way 

 of feeding, training, and external stimulation, will 

 ever convert the pale-fibred " sprinter " into the 

 red-fibred " stayer." Indeed — and from our view 

 this is a crucial social fact — the more we endeavour 

 by environmental influences to change the " sprinter " 

 into the " stayer " the worse we make him. For in 

 Mr. Robertson's words : "It very frequently happens, 

 if an attempt be made to train and race a sprinter 

 over long courses, that he rapidly loses muscle and 

 becomes slow."* In the light of this fact, perhaps 

 we have a more rational explanation of the dullness 

 and stupidity often shown by children in elementary 

 national schools, than that other explanation so 

 often urged by emotional sentimentalists, that these 

 mental defects are due to want of proper food. 



* Page 76. 



