40 VALUE OF FIRST-GENERATION HYBRIDS IN CORN. 



yields than the average of the parents, the amount rangmg as high 

 as 95 per cent. The series inckides experiments in six different States 

 and embraces a wide range of varieties. 



Similar increases are here reported in crosses between the mem- 

 bers of a new series of types of corn from China, Africa, and the 

 American Tropics, very different from United States varieties and 

 very unlike among themselves. These experiments show that a very 

 wide application of this principle is possible. 



In addition to increased yields there is reason to believe that the 

 increased vigor of first-generation hybrids may become an important 

 factor of adaptation to different conditions of growth. Tlie hyl)rids 

 appear not to require the delicate adjustment to local conditions 

 necessary to the pro])er performance of pure strains. The utiliza- 

 tion of hybrids may be expected to extend the range of utility of the 

 high-yielding types beyond the present range of adaptation of such 

 varieties. 



First-generation hybrids are a distinct factor in the problem of 

 securing varieties of corn with adaptations that fit them for special 

 conditions. The increased vigor which these hybrids possess should 

 make possible their growth in regions where pure strains fail and 

 should also provide some measure of disease resistance. 



The advantage of crossing distinct varieties is equally ap{)licable to 

 the improvement of sweet corn and affords a measure of protection 

 to those discovering new and valuable combinations. 



191 



