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THE AMERICAN NATURALIST [Vol. XL V 



which had the highest capacity for the production of 

 the desired qualities. At least in regard to yield and 

 not improbably also in regard to the other qualities for 

 which selections were made, the results were dependent, 

 not upon the isolation of pure types possessing the de- 

 sired quality, but upon the securing and maintaining the 

 proper combination of types. I have shown above that 

 segregation takes place in a manner at least similar to, 

 if not identical with, the well-known behavior of Men- 

 delian characters. As a consequence of this, no strain of 

 corn can be maintained at a high value with respect to 

 any quality whose development is correlated with heter- 

 ozygosis, except by continued selection for the particular 

 qualities desired. If in any such specialized strain selec- 

 tions should be made for a few years on the basis of 

 some character independent of the one used in establish- 

 ing the strain, the superior qualities for which it was 

 originally selected would quickly disappear, owing to 

 the breaking up of the efficient combinations which had 

 been segregated mid maintained by selection. 



The principles here presented have very great poten- 

 tial consequence for the practical grower of corn, and 

 possibly for the breeder of many other cross-breeding 

 plants and of animals. Their importance seems not to 

 have been fully appreciated by any one however, until 

 recently, though several breeders appear to have glimpsed 

 the possibilities at one time or another. Thus G. N. 

 Collins, 9 of the United States Department of Agriculture, 

 has recently shown that several breeders at different 

 times began experiments to test the value of hybridiza- 

 tion in the production of high-yielding strains of corn. 

 The first attempt of this kind which he has found was 

 that of W. J. Beal 10 at the Michigan Agricultural College 

 in 1876. At Professor Beal's instance several other ex- 

 periment stations undertook to work in co-operation with 

 the Michigan Station in testing the value of hybrids in 



9 Collins, G. K, "The value of first generation hybrids in corn," Bull. 

 191, U. S. Bureau of Plant Industry, 45 pp., 1910. 



10 Beal,- W. J., Reports, Michigan Board of Agriculture. 1876-1881. 



