THE REGENERATION OF GONIONEMA. I I 



SUMMARY AND REVIEW. 



Hargitt, '97, showed for the. first time that a medusa when 

 divided into two or several pieces had the capacity to recover the 

 original form, and that various organs, as manubria, canals and 

 tentacles, were also regenerated. He also showed that the proc- 

 ess was a gradual and orderly one. Further experiments in '99 

 by the same author showed that at least in case of radial canals 

 and manubria the process was one of actual generation of new 

 tissue and not merely the recasting of parts of old tissue into 

 new forms. 



Morgan, '99, experimenting on the same medusae, confirmed 

 these results to a certain extent, but claimed that new canals 

 were not regenerated. He showed, moreover, that when cut 

 into quadrants or smaller portions while a similar recovery of 

 form was common, the resulting medusa was not typical in that 

 in many cases there were lacking certains organs, as the typical 

 number of canals, gonads, etc. And furthermore in case of smaller 

 pieces where new manubria were regenerated it was not in the 

 normal position. This observer also claimed that where only a 

 portion of the margin was removed the regeneration of tentacles 

 was more prompt and better developed than where the emargi- 

 nation had been complete. 



As will have been seen, my own experiments confirm in part 

 those of both these observers, and in part extend their results, by 

 showing conclusively the regeneration and functional activity of 

 both radial and marginal canals. My experiments show that 

 when the division of the medusa was in vertical interradial planes 

 that the resulting half medusae were almost always perfectly sym- 

 metrical, while Morgan claimed they were otherwise, in that the 

 manubrium was eccentrically located. This, so far as my experi- 

 ments go, was only true when the section itself was quite unequal. 



I was also able to obtain better results in regeneration of 

 tentacles than either of the authors named, as an inspection of 

 several of the figures will show. Concerning the experiments 

 upon small pieces of medusae, and regeneration of tentacles of 

 partially emarginated specimens my own confirmed in almost all 

 details those of Morgan. 



