FISSION RATE OF STYLONYCHIA PUSTULATA 



489 



3. The third series of experiments 



Experiment 3-A. September 22 to October 21, 1914. 



To further test the results thus far reached, and to determine 

 whether they are based on conditions generally occurring in the 

 organism studied, a new wild individual was obtained from a 

 new mass culture brought into the laboratory September 15, 

 1914. From this, two sets of thirty individuals each, all belong- 

 ing to the seventh filial generation, were obtained, and sub- 



TABLE 13 



Experiment 3-A: Actual number of generations and of selections per ten-day period 

 per thirty lines of the 30 fast and 30 slow lines isolated among the progeny of the 

 single 'wild' individual subjected to opposite selections for 30 days 



TEN'-DAY PERIODS 



Fast Lines: 



Average number of selections. 



Total number of generations. 



Average number of genera- 

 tions 



Slow Lines: 



Average number of selections. 



Total number of generations. 



Average number of genera- 

 tions 



Actual excess in favor of the 



fast lines 



Average excess in favor of the 



fast lines .^ 



Percent the difference is of the 



total for both 



jected, in the manner previously described, one to 'fast,' the 

 other to 'slow' selection. In this series only one individual, in 

 place of two, was selected fi'om each line at each change, and the 

 selections were made daily. There was no reduplication of the 

 fastest and slowest lines. Fourteen of the fast and twenty-one 

 of the slow persisted intact throughout experiments 3-A and 3-B. 

 Opposite selection was practised for thirty days. The records 

 are given in table 13. In all three ten-day periods the fast- 

 selected lines produce more generations than the slow-selected, 



