56 APPLICATION OF PRINCIPLES OP HEREDITY TO BREEDING. 



remarked that the pure strains of corn, because of the close inbreed- 

 ing, had become very weak yielders, while the hybrid yielded an 

 exceedingly large crop. 



Dr. E. M. East, of the Connecticut Agricultural Experiment Sta- 

 tion, in a similar manner produced on small plots at the experiment 

 station yields of corn exceeding 200 bushels per acre from hybrid 

 seed. Here is an important point for the corn breeder. 



A good deal of effort has been made to secure uniformity of the ears 

 in corn by a system of rather close breeding. This method will give 

 the desired uniformity, but the close breeding in a species naturally 

 cross-fertilized is likely to lead to lessened yields. Is it not better 

 to breed for excellence, taking care not to breed too closely, and let 

 uniformity take care of itself ? A method of using two strains of corn 

 in the breeding plot in order to secure hybrid seeds for the field crop 

 has already been described. 



Increased vegetative vigor does not occur in all crosses. Before 

 recommending the cross-breeding of any particular crop in order to 

 secure increased vigor, the fact that in that crop the desired results 

 will follow should be determined. 



The following are other cases of characters which occur only in 

 heterozygote form. In the cross between Black Andalusian fowls 

 and a variety of White Andalusians having black splashes on the 

 feathers, here called White Andalusians for convenience, the hetero- 

 zygote is blue. If these blue fowls be mated with each other one- 

 fourth of their progeny is black, one-half blue, and one-fourth white. 

 If Blue Andalusians are desired, 100 per cent of blues can be obtained 

 only by mating blacks and whites. 



According to Professor Bateson, exactly the same phenomenon 

 occurs in the Bredas, a breed of fowls found in Holland. 



A similar case occurs in the cross between a certain red primrose and 

 a certain white primrose, reported by Professor Bateson. The hetero- 

 zygote is purple and is known to the trade under the name of 

 ''Imperial Primrose." Fifteen years of persistent selection has 

 failed to cause this primrose to come true to seed. Every year one- 

 fourth of its seed produce plants having red flowers, one-half of the 

 seed produce plants having purple flowers, while the remaining one- 

 fourth have white flowers. 



Dr. G. H. Shull found a mottled character in the seed coat of cer- 

 tain flrst-generation hybrid beans which proved to be a heterozygote 

 character; that is, when it appeared it was always heterozygote 

 and would then reappear in only half of the plants whose seeds 

 were mottled. Prof. R. A. Emerson, of the University of Nebraska, 

 found the same character in beans, as did also Professor von Tscher- 

 mak, of Vienna, and Mr. Locke, of Ceylon. 



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