REJUVENESCENCE IN UROLEPTUS MOBILIS 



149 



The results ^Table 6) show that conditions of the conjugation 

 test haqe no stimulating effect on the protoplasmic activities. 

 Indeed there is evidence of a depressing effect as indicated by the 

 average division rates for sixty days. The rates for non-conju- 

 gants are not only lower than that for the ex-con jugant (U 

 Series) but, in all cases, are lower than that of the control parental 

 series. All were descendants of the same series (L series) and 

 all were of the same age. The starved individuals are grouped 

 in four aggregates of five each in table 6, as follows : 



Average division-rate first 10 



days 



Second 10 days 



Third 10 days 



Fourth 10 days 



Fifth 10 days 



Sixth 10 days 



Average division-rate 60 days.... 



PARENT 



RACE 

 L SERIES 



(5 lines) 



8.4 



5.4 

 10.0 

 10.4 

 7.6 

 5.6 



7.9 



EX-CONJU- 

 GANT FROM 

 L series 

 U SERIES 

 (5 LINES) 



9.2 

 14.0 

 13.4 

 14.0 

 13.6 

 13.6 



12.96 



NON-CONJtJGANTS FROM SAME 



CONJUGATION TEST AS U SERIES. 



TWENTY INDIVIDUALS IN 4 



GROUPS OF 5 EACH 



Group 1 Group 2 Group 3 Group 4 



7.0 



5.8 

 4.4 

 7.0 



7.6 

 6.6 

 5.6 



7.6 



7.4 

 6.6 

 6.8 

 8.4 



7.2 

 6.4 



7.1 



6.8 

 5.4 

 5.4 



7.2 

 7.4 



6.5 



There is some evidence, by no means complete as yet, that 

 vitality of the more recent series lacks the endurance of the earlier 

 series. This is apparent in diagram 1, where the curves of the 

 filial series are progressively shorter from the C series to the J 

 series. Both I and J are now in the last stages of metabolic 

 vigor and no further divisions in either series will occur. The 

 I series is now 235 days old, and the J series 200 days, the former 

 having divided 322 times, the latter 253 times. The shortened 

 cycle appears to be accompanied by greater intensity of division 

 energy than in the earlier filial series, the I series having an 

 average division rate of 13.2 divisions in ten days, the J series, 

 12.6 (table 3). In a few months the cycles of the L, N, 0, P, 

 and R series will be complete and will furnish more adequate data 

 for conclusions on this interesting point. 



