206 BREEDING CROP PLANTS 



abnormalities which are isolated. These abnormalities through 

 ordinary seed selection are not eliminated from the commercial 

 variety. Self -fertilized strains, however, stand or fall upon their 



FIG. 48. Average yields of 4 self-fertilized corn strains above; F\ crosses in 

 the center; the double cross below. (After Jones.) 



own merits. Through self-fertilization the unfavorable strains 

 may be eliminated. Crossing of the more desirable strains 

 followed by selection seems a logical method for synthetically 

 producing improved maize varieties. 



