288 



H. S. JENNINGS 



with the culture fluid, in the hope that this would improve the 

 latter. It had the reverse effect, making the animals unhealthy, 

 and almost or quite stopping multiplication. As a result, the 

 figures for the fifth week are very low and irregular for both 

 sets. It would beyond doubt give a more correct idea of the 

 real relations if we should exclude the fifth week entirely, and 

 consider the experiment as ending with the fourth week. But 

 I have not felt justified in suppressing any part of the record, 

 and the main results are clear in spite of the irregularity due to 

 the exceptional conditions of the fifth week. But it will be well 

 to keep in mind the fact that the results obtained from the fifth 

 week have little or no significance on our main problems. 



Rate of fission. Table 2 gives the mean number of fissions for 

 each of the two sets, for each week and for various combinations 

 of weeks; also the ratio of the means for those that have not 

 conjugated (split pairs) to the means for those that have con- 

 jugated. 



TABLE 2 



Experiment 1 . Mean numbers of fissions per week and for certain other periods, 

 in those that have conjugated (pairs) as compared with the same for those that 

 have not conjugated {split pairs); also ratio of the means for the two sets. 



First week 



Second week 



Third week 



Fourth week 



Fifth week 



First two weeks 



Second two weeks 



Four weeks : 



(a) Those that lived 



through 



(b) All, including those 



that did not live to 



end 



Five weeks: 



(a) Those that lived 



through 



(b) All 



MEMBERS OF PAIRS 



No. Mean 



42 



61 



3.279 

 4.661 

 5.000 

 3.976 

 2.737 

 7.589 

 9.306 



0.148 

 0.205 

 0.264 

 0.210 

 0.156 

 0.363 

 0.415 



18.857 ±0.526 



13.918 ± 0.775 



21.842 

 15.902 



0.602 

 0.833 



MEMBERS OF SPLIT 

 PAIRS 



No. 



Mean 



RATIO OF MEAN 



FOR SPLIT PAIRS 



TO MEAN FOR 



PAIRS 



6.729 

 5.932 

 6.678 

 5.102 

 2 . 593 

 12.661 

 11.780 



0.0991 

 0.093 

 0.199; 

 0.130 

 0.113 

 0.144 

 0.287! 



59 24.441 ± 0.352 



59 



24.441 ±0.352 



27.034 ± 0.3S4 

 27.034 ± 0.384 



2.052 

 1.273 

 1.336 

 1.283 

 0.947 

 1.668 

 1.266 



1.296 



1.756 



1.238 

 1.700 



