REGENERATION IN A TROPICAL EARTHWORM. 357 



at once made to secure several thousand worms of this species 

 from various quarters of the town. A considerable number of 

 individuals thus obtained had evidently been deprived in some 

 manner of a head or tail or quite rarely of both ends. One col- 

 lection of more than three hundred worms contained more than 

 a hundred mutilated specimens. This percentage was so high 

 that previous digging was suspected of being the cause of the 

 mutilations. As the collections had been made on successive days 

 over a period of several weeks, it is possible that some at least of 

 the mutilated specimens were produced in this way. In order to 

 avoid this factor, collections were made at several localities which 

 presented every appearance of having been undisturbed for 

 months. Such collections also contained high percentages of 

 mutilated individuals. Practically all the mutilations found were 

 amputations of a head or a tail at an intersegmental furrow. 

 Only three regenerating individuals were found in which excision 

 had occurred in the middle of a segment. In these specimens the 

 missing half segment had been regenerated as well as a portion of 

 the tail behind. One worm mentioned elsewhere had been de- 

 prived of dorsal portions of two segments in addition to the an- 

 terior end. 



Table IV. summarizes the information available from records 

 of the collections. It should be noted that all mutilations included 

 within this table had been produced at least several days previous 

 to the time of collection. Such few specimens as were brought 

 into the laboratory obviously injured as the result of collecting 

 processes were, of course, discarded and not included in the tables. 



Through such collections more than fifteen worms were secured 

 that had lost their heads. Nine were regenerating new anterior 

 ends when brought into the laboratory. Of this latter number 

 four were either immature or if mature had lost more than eight- 

 teen segments, for there were no characteristic sexual markings to 

 make a determination possible. The remaining five specimens 

 had lost their heads anterior to the prostatic segment. By assum- 

 ing that the prostatic segment of each of these animals was the 

 eighteenth metamere before the mutilation, as in normal worms, 

 it was possible to determine the number of segments lost and the 

 type of regeneration that ensued. On the basis of this assump- 



