THE ACTIVITIES OF CORYMORPHA 327 



case of the stalk alone. This response gives more evidence of 

 nervous integration in Corymorpha than any other with which 

 I am acquainted. 



After the separation of the hydranth from the stalk, not only 

 does the stalk continue to respond but the distal tentacles 

 of the hydranth close and open at regular intervals as they 

 did in the normal feeding responses; the rates of response in 

 the two parts are, however, quite different. Thus in a normal 

 polyp whose feeding movements had been carried out for some 

 time at intervals of 2.5 to 3 minutes the hydranth and stalk 

 were separated, after which the stalk responded every 8 to 9 

 minutes and the hydranth every 3.5 to 4 minutes. Thus each 

 part individually had a slower rate than the whole animal, the 

 stalk being much slower than the hydranth. It would be 

 natural to expect that one or other of these parts might serve 

 as a pace-maker for the whole system, but of this there is no 

 evidence. 



In a similar way a stalk may be cut crosswise in halves and 

 the two halves will continue to show rhythmic contractions. As 

 in the former case, both halves have a lower rate than the whole 

 stalk had. Possibly in both cases the reduced rates give evi- 

 dence of a general control which is somewhat disturbed by the 

 cutting, though of this there is no conclusive evidence. 



Besides the type of feeding that has just been considered 

 and that is apparently characteristic of quiet water, a second 

 type is also to be noted (Torrey, '04 a, p. 397). When de- 

 tritus of one kind or another is carried by a gentle current on to 

 the expanded proximal tentacles of an erect Corymorpha, 

 these are very likely to wave inward carrying everything with 

 them toward the distal tentacles, which in turn move quickly 

 outward to meet the incoming proximal members and eventu- 

 ally transport their booty to the mouth (Torrey, ; 04 a, p. 402.) 

 In this way under favorable circumstances much food i doubt- 

 less obtained, but the success of this operation is much more 

 dependent upon accident and the whole procedure seems to 

 have less organized effort about it than the plan of feeding de- 

 scribed for quiet water. 



