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H, S. JENNINGS 



Experiment 11 a: cultivation on slides. From the watch glass 

 (fig. 2, E), thh'ty-two ex-conjugants, from 16 pairs (G, fig. 2) and 

 thirty-two non-con jugants (F, fig. 2) were isolated. These 64 

 lines were cultivated side by side, on slides, under identical 

 conditions. 



In both sets the mortality was high (as I have invariably 

 found to be the case in attempting to cultivate Paramecium 

 aurelia in hot summer weather). By June 13, 25 of the 32 lines 

 of ex-conjugants (G) had died. By June 16 all the ex-conjugant 

 lines were dead, while nine of the non-conjugant lines (F) were 

 still alive. 



In the ex-conjugants the average number of fissions, for those 

 that lived to June 13, was 5.445, while in the non-conjugants, for 

 the same period, it was 7.857. The average rate of fission for 

 all the ex-conjugants (reckoning the rate for each one as long as 

 it lived), was 0.5485 per day, while for the non-conjugants, 

 reckoned the same way, the average rate was 0.7365 per day; so 

 that the rate for the non-conjugants was 34.27 per cent greater 

 than for the ex-conjugants. 



Experiinent 11 b: cultivation in ivatch glasses. Parallel to the 

 slide cultures of 11 a, two watch glass cultures, one of conjugants 

 (fig. 2, K), one of non-conjugants (H), were propagated. One of 

 these contained at the beginning 30 ex-conjugants, the other 30 

 non-conjugants. On each of the following days the animals were 

 removed one by one to a new watch glass, counted, and the 

 number reduced so as to be the same for each. The ratio of the 

 number present on each day to the number present the day 

 before was thus obtained, this may be called the multiplication 

 ratio. It was as follows for eight successive days, beginning 

 June 5: 



