Factors in Regeneration 347 



Many cut ends regenerated but once during this entire period, 

 others as many as ten times. The greater or less regeneration 

 was not confined to any definite region of the stems. The oral 

 ends rarely produced any polyps for reasons already given. The 

 stems continued to regenerate polyps normal in every regard, 

 until the last days of the experiment when they decreased appre- 

 ciably in size. Though observations ceased at the end of 31 days, 

 regeneration of polyps would most likely have continued further. 



EFFECTS OF OTHER INJURIES TO STEMS 



If a Stem or branch is cut at any level and the cut end is exposed 

 to sea-water, a hydranth is normally produced. The question 

 arose whether any severe injury except cutting a stem completely 

 across would result in the formation of a polyp at the point of 

 injury, and whether the regeneration of such adventitious polyps 

 would effect regeneration at the neighboring cut ends. 



Experiment 26. All theinternodes of several stems were either, 

 bored through with a needle, or severely lacerated or slit with a 

 fine scissors. No regeneration at the injured internodes occurred 

 except in two instances. The wound appeared to close up imme- 

 diately, only a crack in the perisarc marked the place of injury. 

 In the two instances, above noted, the hydranths grew out at 

 right angles to the stem, in marked contrast to the hydranths on 

 the rest of the stem, all of which pointed orally. The large num- 

 ber of injuries on each stem did not reduce the number of lateral, 

 oral or basal hydranths regenerated. Nor did the bending of 

 large stems permanently into an acute angle, effect regeneration 

 at any of the cut ends. When, however, one or two internodes 

 on each stem were slit and the stems then bent so that the wounds 

 were kept exposed to the sea-water, a large number of hydranths 

 appeared from the bent ends. It made no difference whether the 

 bend formed an acute or right angle. Nor was regeneration at 

 any of the other cut ends, including oral and basal, effected by 

 the formation of these adventitious hydranths. 



The coenosarc from each of the two injured ends of a slit would 

 grow out directly in line with the axis of the stem, and then fuse 

 into a single branch which would regenerate a hydranth at the 



