56 



The Potato 



yields to the acre will be increased to 156, 312 and 468 

 bushels respectively. If this reasoning were applied to 

 all of the potato fields in the United States, the result 

 would be almost unbelievable. Burbank has made the 

 conservative estimate that if one tuber were added to each 

 hill, the total resulting increase in the United States 

 would be 21,000,000 bushels yearly. 



The following table gives the yields to the acre from 

 hills of certain weights. It is assumed that the hills 

 were 18 inches apart in the rows and the latter were 3 feet 

 apart. This rate of planting gives 9372 hills on an acre : 



Table IX 



METHODS OF IMPKOVEMENT 



Plants are improved in three ways : first, by simple 

 selection, that is, breeding from the best, the object 

 being to improve the present varieties rather than the 

 production of new ones; second, to conduct extensive 

 plantings for the purpose of discovering some unusually 

 good individuals or mutants, which may become the 

 foundation of improved varieties and which subsequently 



