356 S. O. MAST 



it was much smaller. I believe the great variation in the 

 death-rate of the former was largely due to the fact that in the 

 process of isolation the individuals were transferred to solutions 

 consisting of various degrees of dilution of the culture solution in 

 which conjugation occurred. The results of observations made 

 on this point, seem to show that the less the dilution of the 

 solution which induces conjugation the lower the death-rate. 

 If conjugation results in better adaptation to the environment in 

 which it occurs in accord with the contention of Calkins then 

 this is just what would be expected. My observations were, 

 however, not extensive enough to settle the question. I refer 

 to them here merely to indicate that the problem is subject to 

 experimental analysis with the hope of encouraging someone to 

 undertake its solution. 



THE EFFECT OF CONJUGATION ON VARIATION IN THE RATE OF 



FISSION 



All the essential data obtained in regard to the relation be- 

 tween conjugation and variation in the rate of fission are brought 

 together in table 3. This table shows the interrelationship of 

 the different groups of lines; the number of lines in each group 

 the coefficient of variation to three decimal places and the dates 

 of the different periods. The standard deviations were also 

 calculated for all of the periods. They were, however, in such 

 close agreement with corresponding coefficients of variation that 

 their reproduction in the table would have been superfluous. 



By comparing the coefficients of variation for the ex^conju- 

 gants with the corresponding coefficients for the non-conjugants 

 and conjugants separated, it will be seen that while in some in- 

 stances the variation is greater in the ex-con jugants than in the 



TABLE 3 



The effect of conjugation on variation in the rate of fission in Didinium 



Each of the large numbers in the columns is the coefficient of variation for the 

 fission-rate in the different lines of a given group of lines. They represent the 

 variation in the total number of fissions produced by the different lines in the 

 groups during the periods indicated above. The small numbers directly below 

 each coefficient represents the number of lines involved in the calculation of the 

 Goefficient. The brackets and arrows show the origin and the ancestry of the 

 different groups of lines. Conj., Conj. sep., etc., signify the same as in Table 1. 



