The removal of a single oral arm or of the whole eight, in Polyclonia, had much the same effect as the removal of a lithocyst: there was a decided slowing of the rate of pulsation, while the immediate effect of cutting was an acceleration or a return to near the normal rate. About a day later this same animal had quite 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 coördinated 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 Cassiopœa 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 Cassiopœa. A Polyclonia with the eight lithocysts of one side removed, to compare with a normal one, gave no evidence of affected coördination. 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 coördination seemed a little affected, while in another one with a like cut but semicircular, no effect was noticed.