PLANT BREEDING 313 



have been found to contain more than double this amount. 

 It would be impossible to produce the roots in large quan- 

 tities with anywhere near this percentage of sugar, but de- 

 cided gains may easily be secured and an increase of two 

 per cent in the yield would mean a gain of something like 

 !flOO,000 per year in the beet-sugar production of the 

 United States. 



393. Corn-Breeding. — Indian corn is preeminently an 

 American plant, and several varieties of it were known 

 and valued by the Indians before the coming of the whites. 

 The United States at present produces about four-fifths of 

 the world's corn supply', and the 3'early value of the grain 

 alone (excluding that of the leaves and stems used for 

 fodder, ensilage, and so on) amounts to about a biUion 

 dollars. 



Corn breeding is directed mainly to securing some one 

 of these three kinds of results : 



(1) jMore bushels per acre. 



(2) A higher percentage of any of the principal constit- 

 uents of the grain (starch, proteids, or oil). 



(3) Early maturing, to secure a harvest in the northern 

 states where the season is too short for the larger varieties. 



The choice of the best seed would certainly increase our 

 com crop more than ten per cent and add over -¥100,000,- 

 000 per year to its value. 



Corn for human food should contain a high per cent 

 of proteids, and this can readily be secured by using seed 

 chosen for the purpose. Corn-oil is commg to be an im- 

 portant article of commerce for food and for manufactur- 

 ing purposes. The proportion of oil in the grain has been 

 more than doubled by corn-breeders using seed selected 

 for its high oil contents. 



