No. 572] THIRTEEN YEARS OF WHEAT SELECTION 461 



many cases it has not appeared certain that the material 

 studied was a pure line. Since the plants have bred true 

 to type throughout the whole period of study, it is obvi- 

 ous that this criticism will not hold for the data herein 

 presented. 



The work has been conducted at this station under the 

 direction of Professor W. M. Hays from 1901 to 1905, 

 under Professor E. C. Parker 1905 to 1908, under Pro- 

 fessor Andrew Boss from 1908 to 1911 and under Pro- 

 fessor C. P. Bull 1911 to 1913. 



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5 







Selection to Increase Yield 

 The varieties studied, the average annual yield of each 

 variety and the average yield per plant for the six vari- 

 eties under test are shown in Table I. In the years 1903 

 and 190-4 weather conditions were unfavorable, making 

 it impracticable to obtain correct average yields per 

 plant, so data for these years were omitted. However, 

 selections of the best plants were made in these two 

 seasons as in the others and the best seed from them 

 were kept for planting, so the continuous selection for 

 increased yield was uninterrupted. 



