HABITS AND REACTIONS OF SAGARTIA DAVIS1. 2 I I 



stimulators with uniform results. Small amphipods were devoured 

 with avidity. The response differed according as the stimulus 

 was applied locally or generally. For my first experiment I 

 placed a small piece of worm on several of the outstretched ten- 

 tacles of a polyp. The tentacles immediately adhered, bending 

 at and toward the point stimulated, as though responding to a 

 purely mechanical stimulus, and then contracted, dragging the 

 morsel to the mouth. For some seconds the tentacles not in 

 contact with it remained motionless. Then, one or two at a time, 

 they waved slowly inward and grasped the flesh, almost every 

 tentacle finally becoming thus engaged. This experiment was 

 tried many times with similar results. Apparently the tentacles 

 not mechanically stimulated were irritated by substances in solu- 

 tion diffusing out of the flesh, and the reaction was as definite as 

 it would have been if induced by a mechanical stimulus. The 

 movement was toward the stimulus. 



The possibility of an indirect stimulation of these tentacles 

 through the oral disk from the tentacles touching the flesh was 

 eliminated by holding a piece of worm flesh immediately above the 

 mouth of another polyp. In a few seconds some of the tentacles 

 began to twitch slightly, and a little later all began to wave slowly 

 inward, toward the flesh, finally grasping it. A similar result 

 followed numerous trials. 



Next, a bit of flesh was placed on the aquarium floor, near, 

 but not in contact with the foot disk of another polyp. Would 

 the tentacles bend in the direction of the flesh now, or toward the 

 mouth? This experiment, repeated a number of times, did not 

 give uniform results. In the majority of cases the tentacles 

 waved toward the mouth, away from the flesh. In the rest they 

 moved toward the flesh in the most definite and unmistakable 

 manner. Not only that ; the column, in several cases, bent 

 toward the morsel which was seized by the tentacles nearest it 

 and dragged toward the mouth. There is no doubt here that 

 the movements were in the direction of the stimulating object, 

 and are thus comparable to the well-known movements of the 

 manubria of various mendusae toward stimulated points on the 

 subumbrella. The proboscis of Corymorpha reacts similarly, as 

 will be shown in a forthcoming paper. 



