194 THE ELEMENTAEY NERVOUS SYSTEM 



acteristic sets of responses in Corymorplia. In an aqua- 

 rium through which a gentle current of water has been 

 sweeping and in which the specimens of Corymorpha 

 have become well acclimated, they will be found well fixed 

 in the silt, with stalks upright and with their hydranths 

 pointing in the direction in which the current Hows. If 

 the current is now shut oft', feeding movements will be- 

 gin in about three to fourth minutes. These have been 

 briefly described by Torrey (1904 b) and consist of the 

 following steps. At the beginning of a feeding move- 

 ment the expanded proximal tentacles with two or three 

 convulsive efforts are drawn together around the pro- 

 boscis and at the same tune the stalk is shortened. The 

 stalk then curves so that the hydranth is brought close 

 to the mud. The proximal tentacles are opened and the 

 distal tentacles and proboscis are applied to the mud. 

 The stalk then slowly straightens and becomes vertical, 

 the proximal tentacles attaining full expansion as the 

 resting position from which the response started is again 

 assumed. The whole response partakes of the nature of 

 a deep bow and requires for its completion about one 

 minute. As a result of it many small bits of detritus 

 and the like become entangled among the distal tentacles, 

 whence they are transferred to the mouth. The proximal 

 tentacles seem to play a very minor part in this type of 

 food gathering. Records on a single individual showed 

 that in one hour twenty feeding movements were made. 

 Of the three minutes involved in each interval, for the 

 intervals were very regular, about one minute was taken 

 up in the actual feeding movement and about two in rest. 

 When a Corymorpha that has been exhibiting a regu- 

 lar sequence of feeding movements in quiet water is sub- 

 jected to a current of water, these movements cease at 



