HYBRIDIZATION METHODS IN CORN BREEDING. 99 



particulars fundamentally alike, but as they approach the subject from 

 somewhat different points of view it will be interesting to compare 

 them briefly. 



The suggestion for a hybridization method in corn breeding is 

 not entirely new. A very clear outline of such a method, with ex- 

 perimental results sufficient to warrant the suggestion, was presented 

 by Morrow and Gardner in Bulletins 25 and 31 of the Illinois Agri- 

 cultural Experiment Station in 1893 and 1894. These bulletins were 

 evidently unknown to two of the three writers above mentioned/ 1 and 

 the third, Mr. Collins, while referring to Morrow and Gardner's 

 bulletins, makes no statement of the fact that they had devised an 

 adequate hybridization method for the practical utilization of the 

 advantage shown by them to be sometimes attainable by crossing 

 two distinct varieties. 



In my paper on "The composition of a field of maize," read before 

 the American Breeders Association in Washington two years ago, 

 I pointed out the fundamental defect of the method now in general 

 use, which simulates to a degree the isolation methods so successfully 

 used in the improvement of small grains, and I suggested there that 

 "continuous hybridization is perhaps the proper aim of the corn 

 breeder." The conceptions which formed the basis of that paper 

 were the complex hybridity of corn as ordinarily grown and the 

 stimulating effect Ow- heterozygosis or hybridity. It was shown that 

 this stimulating effect comes into play in corn breeding because self- 

 fertilizations result in the partial or complete isolation of many quite 

 distinct strains, and that cross-fertilization must therefore result in 

 the production of hybrid combinations of these pure strains. 



My suggestion for a pure-line method in corn breeding was a 

 direct logical sequel of this original paper on "The composition of 

 a field of maize." Dr. East's article on inbreeding above mentioned 

 is also a sequel to the same paper, as shown by his references to it 

 and also by his excellent discussion of the stimulation which results 

 from hybridity, in regard to which he has arrived at views identical 

 with those entertained by me at the time my original corn paper was 

 written. It may be said, therefore, that Dr. East's paper and my 



a I am indebted to Prof. W. J. Spillman for calling my attention to these 

 bulletins. Dr. East has informed me since this was written and read at Omaha, that 

 he, too, knew of the existence of Morrow and Gardner's bulletins or. corn, but was 

 not aware that these authors had described a method for continuous hybridization 

 in the culture of this crop. G. H. S. 



