HYBRIDIZATION 



563 



ccptiblo to Rust, with Wheat, iniiuuno to Rust but less desirable 

 in other features, a type of Wheat having the Rust resistance 

 of one parent and the desirable features of the other has been 

 obtained. Cotton producing longer and better lint has l^een 

 obtained by crossing the Sea Island Cotton with the Upland 

 Cottons. There are many instances in which more desirable 

 races have ])een secured through hybridization. 



Fig. 48G. — The effect of three degrees of relationship in breeding Corn. 

 Nos. 3 and 4 are pure strains from seed-stock inbred for three years. No. 2 

 is from a closc-fertihzed seed-stock, the plants each year being fertilized with 

 pollen from sister plants grown from the same ear. No. 1 is from seed-stock 

 that has been cross-fertilized for three years. After Montgomery. 



The greatest advantage arising from hybridization is among 

 plants propagated by vegetative methods, as by tubers, bulbs, 

 cuttings, layering, grafting, etc.; for in these cases the progeny 

 is simply a continuation of the hybrid individual and not the 

 result of the fusion of gametes. Many berries, vegetables, fruit 

 trees, and ornamental plants are hybrids. By crossing different 

 kinds of Strawberries, hybrids more desirable than either of the 

 parents have been obtained, and since they propagate by run- 



