lo6 Amos W. Peters. 



the result was the same. In both cases the piece without the 

 sense organ, as well as that with it, was phosphorescent. 



It the whole animal had been made phosphorescent in the dark- 

 box before the operation, both pieces retained phosphorescence; 

 if the whole animal was originally non-phosphorescent, the pieces 

 acquired this property in the dark-box. 



Numerous tests were made to determine whether after trans- 

 verse or longitudinal division the piece retaining the sense organ 

 acquired phosphorescence sooner or later than the other piece. 

 A normal animal, as a check, was subjected to the same test at the 

 same time. The results seemed to follow the law of chance. 

 Sometimes the piece with the sense organ phosphoresced more 

 quickly than the other, sometimes more slowly. The results 

 were hence negative and warrant the statement that the sense 

 organ is not a controlling center for phosphorescence. 



It was now clear that phosphorescence was localized somewhere 

 in or near the paddle plates, and that the reaction-chain from 

 stimulation to response consists very probably of an anatomically 

 short and entirely local series of elements, z. e., there is no distant 

 central station for the reception, modification, or dispatch of 

 impulses. Although it was shown that phosphorescence bears a 

 local relation to the paddle plates the question was still open 

 whether any necessary relation existed. 



The attempt was therefore made to ascertain by experiment 

 whether all movement of the paddle plates are accompanied with 

 phosphorescence. A glass evaporating dish eight inches in 

 diameter and three inches in depth was filled with sea-water to 

 within half an inch of the top. At night a single medium-sized 

 and strongly phosphorescent ctenophore was placed in the dish in 

 the dark-room. The whole was left undisturbed for some time 

 to insure the absence of currents originating from external me- 

 chanical disturbance of the dish. At intervals the dark-room was 

 sufficiently illuminated to enable the observer to note the position 

 of the animal in the dish. During the dark periods the attention 

 of the experimenter was directed upon the dish for the purpose of 

 observing phosphorescence, if any occurred. The result was that 

 though the ctenophore was almost constantly changing position, 

 sometimes to the extent of half the diameter of the dish, yet it 

 showed no phosphorescence during the great majority of the dark 

 intervals. Evidently during such intervals "the paddle plates are 



