REGENERATIVE POTENCIES OF DISSOCIATED CELLS. 37I 



of similar experiments by Dr. Wilson, which reached Naples 

 about April i, just when my own experiments were being con- 

 cluded, results of which had already been written and some of 

 which will appear in the following sections just as originally 

 prepared. I immediately wrote Professor Wilson, giving a brief 

 account of my work and stating that my results would be held 

 pending the appearance of his completed report. This appeared 

 in due course ('ii). While dealing in the main with different 

 material yet he had employed essentially the same methods 

 which I had followed and they seemed so conclusive that I had 

 laid my own paper aside, deeming it unnecessary. However, 

 the report in the Journal of the Marine Biological Associa- 

 tion of similar experiments by DeMorgan and Drew (Oct., '14) 

 which seemed to express some doubt as to the conclusiveness of 

 Wilson's results, prompts me to submit even at this late date 

 my own results, though in somcM^hat abbreviated form. 



Material and Methods. 



Concerning material employed in the experiments mention 

 has been made in the previous section as to the several species 

 used, though two species of medusa instead of one were experi- 

 mented upon. For the most part particular care was taken to 

 have perfectly fresh and vigorous specimens, but it was later 

 found that this precaution was not absolutely essential in all 

 cases, some of my best hydranths having been reared from mater- 

 ial which had been several days in the laboratory before being 

 used. Later mention will also be made of a probable reason why 

 this may happen. One point however calls for special emphasis, 

 namely, that of the freshness and purity of the water used in the 

 experiments. In my work several expedients were employed 

 to guard against the presence of parasitic organisms, especially 

 predatory protozoa. Of most efficiency was that of having 

 water fresh from the open sea. Another expedient was that of 

 sterilizing water of the aquaria, and still a third was that of 

 using synthetic, that is, artificial sea-water. But of all these 

 the first was found to be most satisfactory. 



Concerning methods much might be said, though only the 

 briefest reference will be made of those employed by me. Among 



