No. i.] STUDIES UPON HYDROMEDUSAE. 45 



this paper I have indicated an error in the former paper, as to 

 the paralysis of the Medusa following the complete removal 

 of the marginal portion of the bell. I desire, moreover, to 

 express more definitely than appears in the earlier paper, 

 though it was clearly implied at several points, the fact that 

 in all those experiments there does not appear to be any actual 

 increase of mass, or growth of the body as a whole, but that 

 in all the regenerative activity it was evidently at the expense 

 of other portions of the body proper. This would naturally 

 follow in most cases, since in producing a new manubrium, or 

 new tentacles, or in the grafting experiments, the animal was 

 practically incapacitated for obtaining food, and under the arti- 

 ficial conditions of the experiment could hardly have been suf- 



a 



FIG. 17. 



ficiently fed to make evident any growth. In many cases a 

 very evident decrease in size was apparent in the progress of 

 the experiment. Indeed, in many cases manubrium, velum, 

 tentacles, etc., continued to live for weeks accompanied by a 

 gradual decrease in the body mass, till it finally became wholly 

 consumed, after which the organs gradually disintegrated. 



In all essentials the later experiments confirm those earlier 

 made. Further attempts were made to put specimens under 

 such conditions as would render difficult any mere contraction 

 or approximation of the surfaces. Figs. 17 and 18 will show two 

 out of a considerable number and variety of the experiments. 

 In these the portions of the body were set in their relative 

 positions by bristles in such a way that only continued con- 

 tractions of considerable vigor would be able to change them. 

 But within forty-eight hours the results indicated in the several 

 figures had taken place, the stereotype form of body assumed, 



