BIPARENTAL INHERITANCE IN PARAMECIUM 419 



The mortality in this experiment gives then no indication of 

 sexual differentiation, nor of any other special relation between 

 the members of pairs. The very high mortality, taken in con- 

 nection with the conditions of the experiment, shows that the 

 causes of death were mainly extrinsic. 



Experiment Jj.: Paramecium aurelia 



This Journal, volume 14, 1913, page 304 



In this experiment with the race k, there were included 40 hues 

 derived from 20 complete pairs (2 other lines having lost their 

 mates through accident). Of these, 23 hues died out during the 

 twenty days of the experiment, and among these were both mem- 

 bers of 8 pairs. The most probable number of pairs when 23 

 die out of 40, is 6, if the deaths have no relation to the pairing, 

 although 7 is nearly as probable. Thus the number of pairs that 

 died is greater than would be expected if the deaths had no rela- 

 tion to the pairing; not less, as would be required in order to give 

 evidence of sexual differentiation. The excess is however small, 

 the probability of getting eight pairs being 0.144, so that this 

 would happen in one case out of seven, purely as a matter of 

 chance. No positive conclusions could therefore be drawn from 

 this result, taken by itself. 



Experiment 6: Paramecium aurelia 

 This Journal, volume 14, 1913, page 308 



In this experiment on the pure strain k, lasting six days, 8 

 lines died, out of 16 (derived from 8 pairs). Among these were 

 both members of 3 pairs. The most probable number of pairs, 

 if the deaths are distributed at random, is 2. The chance of 2 

 is 0.522; that of 3 is 0.174. 



Among the 9 lines that died from among 20 derived from 10 

 split pairs, there were both members of 2 spHt pairs. The most 

 probable number, on a chance distribution of deaths, is likewise 2, 



