No. 507] DEVELOPMENT AND HEREDITY 181 



in a modified form, and suggests the following scheme. 

 There must always be corn specialists to continue line 

 breeding, and this method is not for the corn breeder, but 

 the corn grower. The latter should purchase from the 

 line breeder two strains of seed each year, and grow the 

 F 1 generation of the cross between them. 



The method requires a small isolated hybridization plot 

 in addition to the commercial field. In this plot the two 

 strains are planted in alternate rows. The male in- 

 florescence is removed from one strain at flowering time 

 and all of the seed for the commercial field selected from 

 this crossed strain. Some hybrid combinations will be 

 found to be more vigorous than others, but I am con- 

 vinced that practically any cross within the subspecies 

 will be profitable. Crosses between the subspecies, while 

 more vigorous than the mean between the parents, have 

 certain disadvantages, such as variation in the time of 

 ripening, which make them less desirable for practical 

 use. 



