90 



Scientific Proceedings (52). 



60 (756) 



Changes in concentration of sea water and their influence upon 



regeneration. 



By A. J. Goldfarb. 



[From the Biologic Laboratories of the College of the City of New York.} 



The regeneration under changed densities of sea water was 

 observed under conditions that ensured the elimination or uni- 

 formity of associated factors such as size of medusae, volume, 

 surface and depth of solutions, extent of injury, level of amputa- 

 tion, temperature, crowding, aeration, etc. Furthermore, the 

 dilute solutions were made with water containing a known quan- 

 tity of sea salts, and the concentrated solutions were made by 

 slow evaporation in the sun's heat, which corrected certain errors 

 in previous experiments of this nature. The results were checked 

 by repeated observations, plotted for intervals of 14, 24 and 30 

 days, after amputation of the arms of Cassiopea xamanacha. 



These medusae lived in solutions ranging from 40 to 153 per 

 centum of the salts of sea water. They regenerated however in 

 50 to 133 per cent, solutions. The regeneration of normal arms 

 and supernumerary arms was limited further to 75 to 105 per 

 cent, solutions. Beyond these limits regeneration was atypic. 

 Optimum regeneration occurred not in sea water but in sea water 

 diluted 95 to 90 per cent. With increasing dilution the amount 

 regenerated was diminished very slowly, with increasing con- 

 centration very rapidly. The subsequent examinations revealed 

 the fact that in the sub-optimum solutions the arms regenerated 

 absolutely and relatively faster than in any of the other solu- 

 tions, correspondingly changing the character of the curve. 



When the results were compared with those of Loeb it was 

 found that both the hydroid Endendrium of Woods Hole, Mass., 

 as well as Cassiopea of Dry Tortugas, Fla., differed radically from 

 the classic experiments of Loeb on Tubularia of Naples, in respect 

 to the range of solutions in which animals lived or regenerated, 

 the optimum solutions, the normality of the regenerated parts 

 and the character of the curve. It is altogether probable that 

 Loeb's curve is limited to Tubularia of Naples and does not 



