Regeneration in Rhizostoma Piihno. 



83 



In this case the original operation had removed six rhopalia, 

 leaving but two. Soon after the appearance of the new rhopalia, 

 but before they had begun to approach complete development, or 

 before there was any indication of the presence of lithocysts or 

 pigment, the two original organs were carefully removed, and in 

 this case with what might likewise have been anticipated, namely, 

 the complete inhibition of the normal rhythm and the consequent 

 paralysis of the organism. This inhibition continued during the 



Fig. 2. 

 Section of rhopalium in early stage of regeneration, ect, ectoderm; ent, ento- 

 derm ; h, hood ; mgl, mesogloea ; r. c, radial canal ; s. e., sensory epithelium. 



following two days. With the continued development of the 

 new rhopalia activity was recovered, though, owing to the Inter- 

 position just at this juncture of an unhealthy condition of the 

 medusa, it failed to entirely recover the usual vigor or tone which 

 the others had shown. 



These experiments, abundantly corroborated by subsequent ones, 

 leave no shadow of doubt, it seems to me, as to the capacity of 



