PLANT BREEDING 3138 
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 dn increase of two 
per cent in the yield would mean a gain of something like 
$100,000 per year in the beet-sugar production of the 
United States. 
393. Corn-Breeding. — Indian corn is preéminently 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 yearly value of the grain 
alone (excluding that of the leaves and stems used for 
fodder, ensilage, and so on) amounts to about a billion 
dollars. 
Corn breeding is directed mainly to securing some one 
of these three kinds of results: 
(1) More 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 
corn 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 coming 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. 
