PHYSIOLOGICAL VARIATIONS IN PARAMECIUM 



519 



Lr 



tx CcrvJVMNT fHOM A I 

 A I COMTROL 



3b9 



Diagram 8 



days, while the remaining three Hved for more than two months 

 in culture. One whose history we give below living in isolation 

 cultures for a little more than five months. 



From the natm-e of the mixture it is impossible to compare 

 with certainty the division rate of the split individual with that 

 of the actual line from which it was derived. But we can get 

 faii'ly close to it indirectly by comparing its division rate with 

 the rates of all of the eight lines which were running at that time. 

 Its ancestral line, and therefore, control line, must have been one 

 of these eight. Table 9 gives the exact number of divisions in ' 

 consecutive ten day periods for all eight possible ancestral lines 

 (comprising the same dates of course for all lines). 



In one hundred and fifty days the split individual divided 180 

 times. Al of the regular series divided 181 times in the same 

 period, while none of the other lines came very close, A 2 with 

 169 divisions being the nearest. Jennings has shown that split 

 individuals do not vary from the mean of the stock from which 

 they were selected, hence it is probable that the spht ex-conju- 

 gant whose history is given above was derived from the A 1 line, 

 or the same line from which the ex-con jugant in table 8 was de- 



