266 Charles Zeleny 



METHOD 



An abundance of material of all sizes was obtained in the moat 

 of the fort at Tortugas. The animals were found to live very well 

 in glass dishes in the laboratory with but a single change of water 

 each day. Every effort was made to keep all conditions, except 

 the ones used in comparison, as much alike as possible. None 

 of the animals were fed during the experiments and as a result 

 both normal and mutilated specimens decreased in size. Not- 

 withstanding this decrease the animals remained healthy and 

 regenerated readily even after severe injuries. The starving of 

 the animals was necessary because it is impossible to feed equal 

 amounts to animals with different degrees of mutilation. 



DATA AND RESULTS 



I The Influence of Degree of Injury on the Rate of Regeneration 



The rate of regeneration of a single oral arm in each of the 

 following cases was determined: 



a one arm removed at its base; 



b two arms removed at their bases; 



c four arms removed at their bases; 



d six arms removed at their bases; 



e all eight arms removed at their bases; 



/ whole mouth apparatus removed. 



Case / is not an integral part of the series because the arms do 

 not regenerate from the same level as in cases a to e. 



Five groups each similar to the above were obtained, the mem- 

 bers of a group being approximately equal in size. 



The data as given in Table I show that the rate of regeneration 

 of an oral arm is the lowest when that arm alone is removed. 

 From this minimum the rate increases up to the optimum at six, 

 removed arms. It then decreases being less when eight arms are 

 removed. The first five cases in the table are strictly comparable 

 because in each the arms were removed at the base, and therefore, 

 the regeneration is from the same surface in each. In the sixth 

 or last case / this is not true. Here the whole mouth apparatus, 

 including the arms, was removed and regeneration is not from 



