196 THE SMALL GRAINS 



201. Examples of the fixity of pure lines. In some 

 pure-line selections of oats conducted several years by 

 the United States Department of Agriculture, the same 

 process was attempted with Swedish Select oat, a pure 

 strain already selected at Svalof years ago. Much better 

 yielding strains were separated from several standard 

 varieties, but the progeny from selected individuals of 

 the Swedish Select showed little or no change from the 

 parent variety, one way or another. Nilsson records 

 several similar examples at Svalof, giving also negative 

 results. Hutcheson (1914, pp. 459-466) gives the results 

 of 13 years of continuous selection in pure lines of six 

 wheat varieties, in which there has been " no perma- 

 nent improvement." In 3 years' work only, Williams 

 (1912, pp. 409-412) found that there is " no encourage- 

 ment for believing that there is any heritable variation 

 in pure lines of wheat with respect to size of kernels or 

 protein content." Thatcher (1913) states that after 

 5 years of line selection for high and low nitrogen 

 content at the Washington Experiment Station no change 

 has been accomplished. 



202. Centgener method in pure-line breeding. - 

 There are two methods of individual selection, the cent- 

 gener and the plant-row. The first was originated by 

 Hays (1899, pp. 127-134) at the Minnesota Experiment 

 Station. The method begins with foundation beds from 

 bulk seed, planting one kernel in a place at equal distances 

 apart each way. From these beds 10 to 75 of the best 

 individuals are selected for mothers of centgeners. The 

 following year 100 seeds from the progeny of these best 

 plants are planted in square centgener plats, in the 

 same manner as in the foundation beds. After choosing 

 the best plants from the best centgeners for further 



