The Effect of Conjugation. 



59 



Using a longer unit period of 60 days to avoid the minor fluc- 

 tuations of the 1 o-day periods, we find that all ex-con jugant series 

 show a remarkable uniformity in corresponding periods. The 

 standardized diet was not used until the 50th day of the parent A 

 series so the rate for the first 60 days of the A series is not com- 

 puted. The mean division rate, computed biometrically, for the 

 first 60 days of the C series was 8.6333d: .2185, or a rate of 17.26 

 divisions in 10 days; for the first 60 days of the D series, it was 

 8-58333± .1349 or 17.16 in 10 days; for the F series it was 8.6oo± 

 .2320 or 17.2 in 10 days; for the H series it was 8.666 ± .1892 or 

 17-33; for the I series (from F143) it was 8.5833d: .2468, or 17.16; 

 for the J. series (from A 311) it was 8.966^: .2252 or 17.93 an d 

 for the first 60 days of the L series (from I 199) it was 8.7000 ± 

 .2986 or 17.4 divisions in 10 days. All ex-conjugant series, 

 therefore, start with an initial optimum average division rate of 

 l7-± divisions in 10 days. In the second 60-day period for each 

 series, the rate falls to I5.± divisions in 10 days. In the third 

 60-day period the rate falls again to from 8 to 12 divisions in ten 

 days while the variations become more marked. In the fourth 

 60-day period, the average division rate falls still lower, and all 

 series, thus far, have died before the end of the fifth period. This 

 decreasing vitality and death, cannot be due to food or other 

 environmental factors, for, while one series is dying, a filial series 

 whose protoplasm has been under identical conditions for the 

 same length of time, is in full metabolic vigor. The cause of 

 depression and death is endogenous, not exogenous. 



Second, as regards the effect of conjugation on vitality. This 

 question obviously is already answered by the results given 

 above. In every case conjugation results in restoring the lagging 

 activities to optimum metabolic vigor, indicated by the rate of 

 17 + divisions in 10 days, for the first 60-day period. It is still 

 more obvious if we compare the metabolic activity of this pro- 

 toplasm after it has conjugated, with a portion of the same pro- 

 toplasm which has not conjugated. Thus the J series was derived 

 from an ex-conjugant of the A series when the latter was in the 

 311th generation and nearly exhausted. The mean division rate 

 of the offspring (J) was 17.9 divisions in 10 days while that of the 

 parent (A) for the same calendar period, was only 0.25 divisions 



