20 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



regained its normal rate of pulsation and continued to live over two 

 weeks. A long latent period followed the cutting of an arm, before 

 the stimulation of cutting manifested itself. 



An Aurelia, with all its lithocysts removed, still gave spontaneous 

 and coordinated contractions after allowing time for recovery from 

 the operation. This was the result in one instance, while in several 

 others only a few contractions were observed. Removal of the 

 sixteen marginal bodies (lithocysts) in a Cassiopoea produced paralysis 

 for a time but recovery soon followed. A Polyclonia with its entire 

 margin removed was paralyzed but had so far recovered in a day 

 as to be able, at intervals, to give spontaneous pulsations. 



The removed margin of a Polyclonia pulsated vigorously. This 

 margin was then split so as to make a ring within a ring but 

 connected at one point by a small bridge of tissue. The waves of 

 contraction, which always originated on the ring with the lithocysts, 

 passed the bridge to the inner ring quite as Romanes experienced. 

 The outer ring was next split so as to separate the exumbral 

 portion from the subumbral, when it was found that the contractions 

 always originated from the latter. Seven days after its removal, 

 this same margin was still alive and pulsating vigorously, and 

 broken-off pieces of the subumbral portion were pulsating by 

 themselves. Fifteen of the ganglia were removed. It was then 

 found that while most of the pulsations originated at the remaining 

 ganglion, now and then contractions originated in other parts where 

 no ganglion remained. Two days later this margin was still alive 

 with contractions originating as often from other parts as from the 

 ganglion. A similar observation was made on a margin of Cassiopoea. 



A Polyclonia with the eight lithocysts of one side removed, to 

 compare with a normal one, gave no evidence of affected coordination. 



An oral lobe from an Aurelia could give contractions some 

 minutes after removal. 



In another Aurelia a circular cut was made about the base of 

 the oral lobes through the epithelium of the subumbrella. The 

 animal could pulsate well enough but coordination seemed a little 

 affected, while in another one with a like cut but semicircular, no 

 effect was noticed. 



These results on the removal of the lithocysts (and margin in 

 Polyclonia) in Aurelia, Polyclonia and Cassiopoea agree quite with 

 those on Charybdea and, of course, also with Romanes 1 and Eimer's 



