520 



G. N. CALKINS AND L. H. GREGORY 



rived approximately at the same time (the ex-conjugant was con- 

 jugating December 8, the split pair was conjugating December 12 

 four days later). From table 8 it can be seen that the ex-con- 

 jugant divided 211 times during the one hundred and fifty days 

 that Al was dividing 181 times and the split conjugant 180 

 times. If the split conjugant had been derived from any one of 

 the other lines of A or B, the discrepancy would have been still 

 greater. 



This experiment demonstrates therefore that conjugation be- 

 ing the only known factor of difference in the individuals com- 

 pared, was the reason for the greater vigor of the ex-conjugant 

 while the individual ready for conjugation but prevented by 

 splitting, retained the level of vitality of the line from which it 

 was derived. 



TABLE 9 



"Split" conjugant, December I4, 1901-May 11, 1902. Number of divisions in 

 10-day periods of split conjugant and all possible ancestral lines 



