16 



SERGIUS MORGULIS 



same lot the operation was executed twice during a similar period 

 of time. On looking through table 6, it will be noticed that in the 

 course of four weeks the worms have regenerated on the average 

 8.4 segments (5 to 14 segments). From previous studies on 

 Podarke (Morgulis, '09b), it is well known that the largest 

 number of segments was regenerated within the first two weeks 

 after the operation. 



TABLE 6 



JULY 2 — JULY 30 



Old segments. . 

 New segments. 



17 

 8.4 



Table 7 contains the records of an experiment where the worms 

 were operated on twice during the four weeks, the second opera- 

 tion having been executed at the end of two weeks. At that time 

 the average number of regenerated segments was 6.2, the number 

 ranging from 5 to 8 segments in different individuals. The stage 

 of greatest regenerative rate had thus been passed at the time the 

 regenerated tails were cut off, and the worms were left to regen- 

 erate anew for another two weeks. The average number of seg- 

 ments regenerated for the second period of two weeks is only 

 5.4, ranging from 4 to 7 segments, showing very definitely that 

 the rate of regeneration following the second operation was slower. 

 There is no significance in arguing that the decrease in the rate 

 of regeneration following an operation once repeated is no decrease 

 at all, but the outcome of a "general decline of the physiological 



