298 H. S. JENNINGS 



As the table shows, although the means for the conjugants are 

 throughout less (table 6), their standard deviations are as* a rule 

 greater than the standard deviations for those that have not 

 conjugated. As a result, the coefficient of variation (standard 

 deviation divided by the mean) is in every case much greater for 

 those that have conjugated. For the first week the variation, as 

 measured by this coefficient, is twice as great in the conjugants. 

 For the entire eight weeks it is nearly twice as great. 



Thus in this experiment, as in the former one, conjugation has 

 the effect of greatly increasing the variability of the fission rate. 



Mortality. Owing to the high general mortahty, due to imper- 

 fect culture methods, the distribution of deaths in this experiment 

 is of much less significance than in Experiment 1. It is sum- 

 marized in table 8. 



As the table shows, the death rate was greater in those that 

 had conjugated than in those that had not, in every week save 

 the second. In the second week I tried the experiment of adding 

 to the cultures water from a pool that was extremely foul, but 

 contained many Paramecia. It proved disastrous; many of my 

 lines were killed, and among these were a larger proportion of the 

 split pairs and free than of the pairs. I doubt if the distribution 

 in such a catastrophe is of any significance; though possibly it 

 indicates that those that have conjugated are more resistant 

 to such decidedly injurious conditions. 



Throughout the remainder of the experiment (as throughout 

 the entire time in Experiment 1), the mortality was highest among 

 those that had not conjugated. For the entire eight weeks 

 together the mortality is nearly the same for all three classes, 

 but is a little greater for those that have conjugated. 



There appears to be no significant difference, as to mortality, 

 between the split pairs and the free. There is thus no indication 

 that prevention of a conjugation that had been initiated is in any 

 way injurious. 



Abnorinalities. In this experiment, as in Experiment 1, I 

 noted frequent abnormalities among the progefiy of the conju- 

 gants; none among the other sets. No detailed study was made 

 of these. 



