AMKRICAN BREEDERS ASSOCIATION ^7 



form and size of the ear, width, depth, shape, and composition of the 

 grains, and any other feature in which homogeneity may be desired. 

 This is doubtless the explanation of the interesting experience related 

 by Mr. Joseph I. Wing at the meeting of the American Breeders' 

 Association in Columbus two years ago. His father had selected a 

 very fine deep-grained variety of corn in which great uniformity had 

 been attained but only at the expense of decreased yield. 

 In the pure-line method outlined below all individuals in the field 

 will be Fj hybrids between the same two homozygous strains, and 

 there are theoretical grounds for expecting that both in, yield and 

 uniformity superior results should be secured. Thus, every individual 

 will be as complex as every other one and should produce an equal yield 

 of grain if given an equal environmental opportunity, so that in so far 

 as hereditary influences are concerned the vigor of the entire crop 

 should be equal to the best plants produced by the methods now in 

 use. This would seem to result necessarily in a larger yield than can 

 be produced by the present method. But not only will all the plants 

 in the field have the same degree of complexity, but they will all be 

 made up of the same combination of hereditary elements, and conse- 

 quently there must result such uniformity as is at present unknown in 

 corn. 



With such a prospect as this, I believe we will be sufficiently interested 

 to make the discussion of the method by which such results are to be 

 attained worth while. The question naturally arises as to whether the 

 technique of the new method will be sufficiently simple to make it 

 practicable. To this question I believe I can safely answer that the 

 pure-line method will be considered simpler than the elaborate one now 

 in use among the most careful breeders, e. g., those at the Illinois, Con- 

 necticut, and Ohio State Experiment Stations. The process may be 

 considered under two heads: (i) Finding the best pure-lines; and (2) 

 The practical use of the pure-lines in the production of seed-corn. 



(i) In finding the best pure-lines it will be necessary to make as 

 many self-fertilizations as practicable, and to continue these year after 

 year until the homozygous state is nearly or quite attained. Then all 

 possible crosses are to be made among these different pure strains and 

 the F! plants coming from each such cross are to be grown in the form 

 of an ear-to-the-row test, each row being the product of a different 

 cross. These cross-bred rows are then studied as to yield and the pos- 

 session of other desirable qualities. One combination will be best 

 suited for one purpose, another for another purpose. Thus, if the self- 

 fertilized strains be designated by the letters of the alphabet, it may 



