16 



Scientific Proceedings (ioi). 



3 to 6 days and the process may be watched in the living cell in 

 which the changes of the nucleus are clearly visible. The in- 

 dividual forming the V series required seven days for this reor- 

 ganization. 



It was most unexpected and interesting to find that the cut 

 individuals invariably went through the same nuclear reorganiza- 

 tion states as those of a normal ex-conjugant. If they died, death 

 was always at the last phase of the reorganization process. The 

 individuals destined to live and form the X series, the X6 series, 

 and the X7 series, required eight, nine, and eight days respectively 

 before the first division of the young cells. From the start each 

 series represented by five different lines, was carried on in cul- 

 ture like any normal ex-conjugant series, with similar records of 

 the daily division rate, the average rate for ten days, and the 

 average rate for the first and second sixty- day periods. The 

 results for the four months following the operations are given in 

 the following table. 



Average Division Rates in io-Day Periods, of Controls and Experimental 



Series. 





Parent 

 P Series 

 Non- 

 conju- 

 gant. 



Filial 

 V Series 

 Ex-con- 

 jugant. 



X Series 



Cat 

 Conju- 

 gating. 



V Series 

 Control 

 Ex-con- 

 jugant. 



P Series 

 Control 

 Non- 

 conju- 

 gant. 



X 6 

 Series 



Cut 

 Conju- 

 gating. 



<; X - 7 

 Series 



Cut 

 Conju- 

 gating. 



V Series 

 Control 

 Ex-con- 

 jugant. 



P Series 

 Control 

 Non- 

 conju- 

 gant. 



ISt " " 



13.6 



13-8 



8.8 



13-8 



13-2 



15.8 



17.6 



18.2 



12.4 



2d M " 



12.8 



16.0 



9-4 



14.6 



10. 0 



13-3 



16.4 



16.8 



12.2 



3d " " 



13-2 



13.8 



13-4 



18.2 



12.4 



15-8 



18.6 



18.2 



16.8 



4th " 



10.0 



14.6 



13-4 



16.8 



12.2 



14.0 



15.8 



14.8 



13.2 



5th ■ " 



12.4 



18.2 



14.2 



18.2 



16.8 



132 



15-4 



17.0 



I6.4 



6th " " 



12.2 



16.8 



12.0 



14.8 



13-2 



14.0 



16.8 



16.6 



14-4 



1st 60 " 



12.4 



155 



II-9 



16.0 



12.9 



14-3 



16.8 



16.9 



14.2 



2d 60 " 



14.2 



16.3 



12.5 



14.8 



11-5 



10.3 



12.0 



12.9 



7-7 



Average 120 



13-3 



15-9 



12.2 



15-4 



12.2 



12.3 



14.4 



14.9 



10.9 



days. 





















It has been shown in an earlier paper 1 that the extent of re- 

 juvenescence as indicated by the division rate, varies with the 

 age of the parent series at the time of conjugation. The greater 

 the vitality of the parent series the less is the difference in vitality 

 between parent and filial series. For example, if the filial series 

 starts by a conjugation occurring during the first 60 days (ap- 



1 Calkins. " UroUptus mobilis. VL The Renewal of Vitality through Con- 

 jugation." Jour. Exper. Zool., Vol. 29, No. 1, 1919. 



