242 POWER AND THE PLOTV 



The future will see a wider variety of equipment for the ap- 

 plication of power to the work of the farm than would ever 

 have been possible with animal power alone. Man has made 

 no fundamental change in the horse in thousands of years of 

 breeding and selection. In a single generation he has produced 

 mechanical motors with much greater variation in speed than 

 exists between the Belgian and the thoroughbred; with vastly 

 greater difference in size than between the Shire and the Shet- 

 land; and with thousands of differences in design, materials, 

 and construction that breeders have never been able to create 

 in flesh and blood. 



