298 HELEN DEAN KING. 



droids and well-developed tentacle anlagen were present on the 

 other branches ; there was no indication of a regeneration at the 

 oral end of any of the stems. The next day all of the branches 

 bore hydranths, and in but one case had any regeneration taken 

 place at the oral end of the stem. In this instance, the stem 

 extended about o. 5 mm. above the place of insertion of the 

 branch and a considerable amount of red pigment had collected 

 at its extreme oral end. In the course of forty-eight hours more 

 a polyp formed on the oral end of this stem but no regeneration 

 took place at the oral end of any of the other stems, although 

 they were kept for over a week. 



Series 6. Sixteen experiments were made in which the branches 

 were cut off very close to their origin on the stem. The oral 

 end of the stem was then removed leaving a piece about 5 mm. 

 in length above the origin of the branch, in order to see whether 

 the formation of a hydranth at the oral end of the stem would 

 prevent or merely delay the formation of a polyp at the place 

 where the branch was removed. In all cases the wound in the 

 side of the stem healed over very quickly and, although the 

 hydroids were kept alive for a number of days, no regeneration 

 of any kind took place at the point of injury. 



Series 7. - - In ten cases the entire branch was removed from 

 the stem, but the old hydranth at the distal end of the stem was 

 not cut off. The result was the same as in the previous set ot 

 experiments, as the cut surface was very soon covered over and 

 no subsequent regeneration took place from it. 



Series 8. - - In sixteen cases where long pieces of stem bore 

 from two to four branches, the anterior end of the stem and the 

 apical end of each branch were removed by transverse cuts leav- 

 ing the lengths of the branches approximately the same as that 

 of the stem above the origin of the most anterior branch. The 

 experiments were made to see if there is any difference in the 

 relative rate of regeneration of the anterior branches and of the 

 proximal ones. There was no uniformity whatever in the results 

 of this set of experiments. In some cases a hydranth regenerated 

 on a posterior branch before it did on the oral end of the main 

 stem ; and in other cases all of the branches produced hydranths 

 at the same time that one developed at the oral end of the stem. 



