466 THE AMERICAN NATURALIST [Vol. XLVIII 



elusions. However, the indications are that from a prac- 

 tical breeder's standpoint permanent improvement in 

 pure lines in small grains, if possible, is certainly not 

 rapid or apt to be very marked. Thirteen years of selec- 



Plate III. Average height of all varieties. X-X, fitted straight line. 



tion covers considerable time and expense, and, as far as 

 can be seen from the varieties reported in this paper, it 

 has resulted in no permanent improvement. This would 

 suggest that some other line of improvement must be 

 sought. It is probable that much more rapid progress 

 could be made by segregating pure lines from mixed 

 populations and combining the desirable characters of 

 these lines by hybridization. 



