424 



H. S. JENNINGS AND K. S. LASHLEY 



Experiments by the author 



In my Experiment 1 (this Journal, vol. 14, 1913, page 286) 

 we have the data for determining this point. In this experiment 

 there were 120 Hnes derived from animals that began conjugation; 

 61 from those that were allowed to complete the process, 59 from 

 those that were separated before the union was consummated 

 (spht pairs). In the five weeks during which the experiment 

 was continued, none of the strains from the split pairs died out, 

 showing that any deaths among the progeny of the pairs were not 

 due to lack of a revivifying effect of conjugation. We have al- 

 ready dealt with the deaths among the conjugants (page 416). 

 Here we will deal with the differences between members of pairs 

 in the rate of reproduction. 



The number of fissions for five successive weeks are given for 

 the progeny of each member of the pairs in table 29 of the paper 

 on the effects of conjugation (this Journal, vol. 14, 1913, page 

 379). From this table we may find the average difference be- 

 tween members of pairs in number of fissions for any given period; 

 and also the average difference that would exist if the organisms 

 were paired at random (that is, the average difference between 

 any two individuals of the lot). 



The method by which this is done may be illustrated as follows, 

 taking the fissions for the first week as an example. Here the 

 fissions are distributed among the 60 members of pairs as shown 

 in the following table 38 (data taken from table 29 of the paper 

 on the effects of conjugation '13). 



The differences in number of fissions between the two members 

 a and b of the 30 pairs are distributed as shown in the following 

 table 39 (data from table 29 of the preceding paper). 



TABLE 38 



