THE PURE LINE AND SELECTION 185 



in each of the nineteen instances. When, however, ex- 

 tremes from any pure line series were selected and bred 

 from, the results showed complete regression away from 

 the extreme condition of the parent bean back to the 



Average of_ 

 all progeny" 

 Weight of parent seed \ 



10203040606070 10 20 80 40 BO 60 70 10203040506070 10203040606070 10208040606070 



Pure line number >U VU XV XVIII 



FIG. 24. The result of selection in four pure lines of beans. The 

 vertical columns, representing the average progeny from 

 different sized parents all derived from the same pure line, 

 contain groups nearer alike than the horizontal columns, rep- 

 resenting progeny from the same sized parents, but different 

 pure lines. All the numbers indicate centigrams. Data from 

 Johannsen. 



type of the entire pure line in question. That is, 

 selection within a pure line is absolutely without effect 

 in modifying a particular character in the offspring of 

 the line in question. 



This is illustrated in Figure 24 in which the results 

 of selecting for size in the year 1902 is shown for four 



