32 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 



The pedalia could be made to contract by giving the subumbrella 

 a prick, generally a rather severe one was necessary. The upper 

 part of the subumbrella seems not so sensitive as the lower part and 

 the proboscis, and the base of the stomach did not give any reflex 

 at all (two specimens). One of the two could be made to give the 

 reflex only with much difficulty. This was a very lively one. It 

 would even stand severe pricks on the nerve, or even through the 

 region of the sensory clubs, without contracting the pedalia or stop- 

 ping pulsations. 



Cutting the frenula seemed not to affect the ability to swim well. 

 Cutting in this region brings about the reflex of the pedalia. 



In the preceding fish the velarium was cut away wholly in some 

 places, in other places it was left only as ragged strips. The pedalia 

 became very strongly contracted and the tentacles were brought inside 

 the bell. Pulsations that seemed strong produced much less progress 

 than with the velarium intact. [Repeated.] 



30. One with the whole margin cut off still gave pulsations. Upon 

 the removal of the region of the radial ganglia, however, pulsations 

 were seen no more. 



The velarium in the above continued to give twitchings. The four 

 pedalia were cut off with plenty of the tissue at their bases to insure 

 the removal of interradial ganglia, and twitchings of the velarium with 

 irregular contractions continued. No full contraction all around the 

 velarium was noticed. When all the tissue was trimmed off as nearly 

 as possible down to the velarium, the latter still gave twitchings and 

 irregular contractions as before, even more so as if excited by the 

 operation. The power of originating contractions evidently resides in 

 the velarium or in the ganglion cells of the frenula just as it does in 

 the proboscis and the floor of the stomach. 



Small pieces cut from between the pedalium corners and the 

 frenula, so as to have tissue on them from neither, could contract 

 by themselves. (See also for Pedalia, Experiments 15, 23, 41b ; 

 Velarium 18, 41c.) 



Tentacles. 31. A cut-off tentacle can contract by itself, sometimes 

 with squirming contractions. A prick at either end can produce a 

 forcible contraction. A slight prick at the distal end may produce a 

 local contraction. The proximal end is more sensitive, but this differ- 

 ence is not very marked. One with only the tentacles removed 

 seemed to be a little less able to guide itself well. 



