362 



H. S. JENNINGS 



are the non-conjugants. It will be well to summarize here the 

 coefficients of variation for conjugants and non-conjugants in 

 certain periods of each experiment. This is done in table 26. 



As the coefficient of variation was computed for several dif- 

 ferent periods in most of the experiments, it hardly appears 

 practicable to bring together in table 26 all the coefficients given 

 in the tables of the body of the paper. I have therefore selected 

 the longer periods, with some typical partial periods. 



As table 26 shows, the difference in variability between con- 

 jugants and non-conjugants is not a slight one, but is very great. 

 The coefficient of variation averages at least twice as great for 

 the conjugants, and in some of the cases given in table 26 it is 

 three or four times as great. There can be no question but that 

 conjugation increases greatly the variation in rate of reproduction, 

 both in wild cultures and in pure races. 



If in place of studying the variation relative to the mean rate, 

 as shown by the coefficient of variation, we examine the absolute 

 amount of the variation, as shown by the standard deviation, we 



TABLE 26 



Comparative variability, as measured by the coefficient of variation, for the lines 

 descended from conjxigants and for those descended from non-conjugants, in num- 

 bers of fissions to a given period; for various experiments of the present paper. 



EXPERIMENT 



(Wild Cultuies) 



1 



1 

 « 2 



2 



3 

 (Pure strains) 



4 



5 



13a 

 13b 

 13b 

 13b 

 13b 

 15 

 15 

 15 



First 2 weeks 



Second 2 weeks 



First 2 weeks 



Second 2 weeks 



Four days 



Twenty days 



Six days 



Seven days 



18 Days, December 8-26 



January 2-14 



January 30-February 12. 

 December 8-January 29 



First 12 (11) days 



Later September 8-16. . . 

 24 (21) days 



conjugants 

 (pairs) 



non-conjugants 

 (split pairs) 



Num- 

 ber of 

 lines 



Coefficient 



Num- 

 ber of 

 lines 



Coefficient 



12.975 ± 0.819 

 27.743 ± 1.850 

 21.350 ± 1.489 

 22.847 ± 2 246 

 12.756 ± 1.546 



19.792 ± 2.310 

 14.382 ±1.565 

 17.550 ± 0.953 

 18.263 ± 2.405 

 12.832 ± 1.662 

 19.735 ± 2.821 

 16.428 ± 2.150 

 11.789 ± 0.453 

 8.585 ± 0.315 

 7.122 ±0.284 



