c. The sensory niches of this same animal were treated with 2.5 per cent. acetic acid by means of a pipette. The stalks of all four clubs showed white. Pulsations ceased. The velarium showed feeble local contractions. The movements of the proboscis and suspensoria drawing down the stomach continued. Upon stirring the animal it gave rather feeble, somewhat convulsive pulsations with local (fibrillar) contractions; the pulsations in some cases were pretty well coördinated, but were more on the twitching kind. 13. Three clubs were removed. The animal pulsated well, only a little less strongly, perhaps. After a minute or two the fourth club was removed. It pulsated almost immediately, perhaps thirty seconds after the operation. It swam very well and pulsated feebly five hours after the operation. 14. One from jar (a) (Experiment 6) was operated upon. When the first club was cut off there was a paralysis of pulsation followed by a quick recovery. Cutting off the second club seemed to stimulate pulsation, the third to diminish it; after cutting off the fourth club it still pulsated. When placed in a large jar it pulsated on the bottom, but not strong enough to swim. The pulsations were fairly regular and sometimes seemed to occur in groups of two, but these groups were not well marked. 15. Another one from jar (a) was taken. One club was cut out, upon which there was a very temporary paralysis followed by good pulsations afterwards. The _proboscis_, as in all cases noticed, gave active movements to this side and that side. These movements of the proboscis were often very quick and definitely directed as if a well defined stimulus were given. After the operation one _pedalium_ contracted so as to be at a right angle to the main axis of the bell; shortly a second pedalium also contracted. Placed in a small round dish the animal swam actively. A second club was removed, and it swam as well as before. After fifteen minutes it was not swimming but pulsating against the jar. Upon stirring it a little it swam vigorously ten to fifteen strokes and then stopped. It seemed weak and its movements appeared not so definite, though this might be due to weakness. A third club was removed. The only change seemed to be rather greater weakness. After about five minutes the fourth club was removed. Paralysis of pulsation followed. It had the power to contract its _pedalia_ when these were rather vigorously stimulated with a needle. It also gave one feeble pulsation when so stimulated. 16. The sensory clubs were removed from another. After removal of the third one it still pulsated actively, but stopped completely and apparently for good after the removal of the fourth club. Another one stopped pulsating apparently for good upon removing the third club.