12 SERGIUS MORGULIS 



The depressing effect upon the regenerating tails produced by 

 an extra operation can be seen already during the first week. 

 Thus on July 29 in groups B and C, both at this time containing 

 worms with heads intact, the number of regenerated segments 

 varied from 4 to 6, but in group A, containing decapitated worms, 

 the number of regenerated segments varied from 2 to 4. Com- 

 paring with each other the corresponding data in groups A and 

 C it will be observed that in the former the worms never regen- 

 erated as large a number of segments as are sometimes found 

 in the latter. A scrutiny of the numbers pertaining to group 

 B shows that after the tail had commenced to grow, the removal 

 of the head had no immediate depressing effect upon the regen- 

 erating tails. 



Thus far the experiments were preformed on worms cut through 

 the middle of the body. The question then arose — Would the 

 results be the same for worms regenerating from a more poste- 

 rior level? With this in mind, an experiment was performed, sim- 

 ilar to the one just described, but in this case only about one- 

 sixth of the worm was cut off. The results of this experiment 

 are reported in table 4. 



It will be noticed on glancing over the column under July 29, 

 i.e., one week after the operation, that in this case the number of 

 regenerated segments in all three groups. A, B and C, varies from 

 3 to 4, the number 3 being, perhaps, predominant in the A-group, 

 or 'decapitated worms. For the next ten days (till August 8) there 

 is scarcely a change in the condition, and the worms in group B — 

 decapitated after a week's regeneration — show no indication 

 of either an increase or decrease in their regenerative power fol- 

 lowing the additional operation. 



Comparing the results of the last two experiments on worms 

 regenerating from different posterior levels, it is apparent that 

 the additional injury in the anterior region affects the regenera- 

 tion of the tail the less the more posterior the level of the cut, but 

 that in no case is the tail regeneration accelerated. 



Bearing in mind the importance, for purposes of comparison, 

 of following the process of regeneration step by step from the 

 earliest stages (see Morgulis, '09b), I traced the influence of 



