REGENERATION IN RHIZOSTOMA PULMO. 



BY 



CHARLES W. HARGITT. 



With 6 Figures. 



I. INTRODUCTORY. 



The several experiments, of which this paper presents a resume, 

 were conducted during the early summer of 1903, at the Naples 

 Zoological Station, while occupying the table of the Smithsonian 

 Institution, for the courtesy of which it is a pleasure to express 

 my obligations. 



The primary object of the experiments was to test the regen- 

 erative capacity of the Scyphomedusae and to institute certain 

 comparisons between these results and those obtained by similar 

 experiments previously made upon the Hydromedusae. So far 

 as I am aware no similar experiments have been made upon the 

 Scypliomedusae with the definite purpose of testing this particu- 

 lar aspect of their physiological constitution. Romanes in his 

 experiments upon " Primitive Nervous Systems," '85, has record- 

 ed incidentally the fact that certain mutilations of medusae are 

 promptly healed, but gave no details. Eimer, '78, has also 

 carried on similar experiments and with the same general purpose 

 of testing the character and distribution of nervous centers, but 

 makes no reference to the matter of regeneration. And quite 

 recently Uexkiill, '00, has likewise reviewed these experiments 

 of Romanes and Eimer and carried them somewhat farther than 

 they had done. But while arriving at somewhat different con- 

 clusions, drawn from a series of experiments in some features 

 coincident with those to be described now, he makes no reference 

 to any regenerative processes, devoting attention almost exclusively 

 to the movements, specially those of rhythmic character, and seek- 

 ing physical explanations of them. 



