476 



AUSTIN RALPH MIDDLETON 



90 100 



Fig. 9-a. Curves of variation of the lines of Experiment 1-B, the ninety- 

 days of balanced selection. The ordinates give the number of lines, the abscissae 

 the number of generations produced. The continuous line is the curve of the 

 fast set, the broken line that of the slow set. 



Fig. 9-6 Curves of variation of the first ten fast and first ten slow lines of 

 Experiment 1-B (balanced selection). The ordinates represent numbers of lines, 

 the abscissae, generations. The continuous line is the curve of the fast set, the 

 broken one the curve of the slow set. 



Fig. 9-c Curves of variation of the last twenty fast and last twenty slow 

 lines of Experiment 1-B (balanced selection) . The ordinates represent numbers 

 of lines, the abscissae, generations. The continuous line is the curve of the 

 fast set, the broken one the curve of the slow set. 



rate to survive long continued balanced selection (Experiment 

 1-B) ; 2) To discover what would be the effect if selection con- 

 tinued further on these lines. During the first three ten-day 

 periods there was no further reduplication of extreme lines and 

 tjie slides were changed daily. At the end of the third ten-day 

 period the fastest lines of the fast set and the slowest lines of the 

 slow set were again chosen for reduplication and continued 

 selection, as described for Experiment 1, part 3. This was the 

 only time this was done during the present experiment. The 

 slides were changed every forty-eight hours during the fourth 

 and fifth ten-day periods. The ninth to the thirteenth ten-day 



