Notes on the Physiology of CharyMea rnstonii. 



formed upon several individaals changing the length of the incision 

 In five cases the length of incision, by which the reflex was stopped 

 in the two pedalia opposite the stroked side, was determined to 

 be as follows : 



In a few cases, instead of three rhopalia only two opposite 

 ones were extirpated, and the above experiments were repeated 

 with precisely the same result. From these experiments, as has 

 -already been alluded to, one cannot escape from the conclusion 

 that the upper third of the Charybdea bell does not transmit 

 nerve stimuli notwithstanding the presence of the subumbrellar 

 muscles due in all probability to the absence of nerve plexus 

 there. 



It should be noted that the pedalium is also bent into the 

 bell cavity by stimuli originating from a place other than the rho- 

 palium. If the outer edge of a pedalium, where there are many 

 patches of nematocysts, be stroked, then that pedalium alone con- 

 tracts, the other three remaining relaxed, as was ol)served l)y 

 Conant (Berger '00 p. 31). This reaction is seen in the individuals 

 deprived of all the rhopalia and also in the ring of ]>ell margin 

 made by a circular cut a little below the level of the sensory 

 niches. Such a ring was cut at one place and spread open on 

 the bottom of a vessel containing water. Various places of it were 

 pinched to see how the pedalia acted. In case the pinched place 

 was half way between any two pedalia, these alone contracted. 

 If, however, the place was nearer to one pedalium, that pedalium 

 alone usually contracted, but sometimes two on either side re- 



