HYDROIDS 195 



once, to begin again a few minutes after the current has 

 been cut off. Apparently this type of response in normal 

 animals is dependent upon quiet water. 



If a Corymorplia that is feeding regularly in quiet 

 water is deprived of its hydranth by having it suddenly 

 clipped off at the neck by scissors, the stalk continues the 

 feeding responses but without bowing low enough to bring 

 its distal end close to the substrate. In this sense the 

 response is defective and as the following record shows, 

 it is also slower than before. A normal polyp was found 

 to carry out feeding responses at the following intervals 

 in minutes : 3.5, 3.5, 2.5 ; whereupon its hydranth was cut 

 off and the stalk continued to respond at intervals in min- 

 utes of 5, 4, 5, 4.5, and 5, when the experiment was 

 concluded. 



Another curious effect of beheading a polyp was seen 

 in experiments with pairs of feeding individuals. A pair 

 of polyps regularly feeding in quiet water were watched 

 for a short time and then the hydranth of one was cut 

 off; both individuals, the one without a hydranth as well 

 as the one with a hydranth, continued to carry out bow- 

 ing movements. The circulating current in the aquarium 

 was then turned on, whereat the normal individual ceased 

 to respond while the headless one continued to carry out 

 rhythmic bowing movements. This experiment was often 

 repeated and with uniform results. The water currents 

 in some way stimulate the normal animal so as to cause 

 the feeding responses to cease, a condition that does not 

 obtain in the case of the stalk alone. This response gives 

 more evidence of nervous integration in Corymorpha 

 than any other thus far discovered. 



After the separation of the hydranth from the stalk, 

 not only does the stalk continue to respond, but the distal 



