54 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



muscles of the aboral end relaxed and the meat taken 

 in before by this mouth fell out. When I fed the 

 mouths in succession, the mouth that was fed first 

 ejected the food as soon as the other began to eat. 

 It is obvious from this that a peristaltic wave is 

 started from the end which takes up food. 



Thus far we have considered only the head-piece. 

 If we turn our attention now to the foot-piece, we 

 find that on the oral end a new oral disc with tentacles 

 soon begins to form. Before this has occurred, how- 



o 



ever, the mouth takes pieces of meat and swallows 

 them. It seemed to me as though this new mouth, 

 even before the regeneration of the oral disc, re- 

 sembled the normal mouth more than the aboral 

 mouth in the head-piece, for it did not accept paper 

 wads and grains of sand, while it swallowed meat 

 well. 



4. In the foot of the Actinians the contact-irrita- 

 bility is of special interest. The foot of a normal 

 Actinia equina attaches itself to the surface of solid 

 bodies. The character of the surface is of great im- 

 portance for producing these processes of attachment. 

 If it finds no other body, the Actinian attaches itself 

 to the glass of the aquarium, and glides about on it. 

 If, however, the shell of a Mytilus is placed in the 

 aquarium and the animal comes in contact with it 

 while moving about, it immediately attaches itself to 

 the shell, and remains there, whether the shell is 

 empty or inhabited. The surface of an ulva leaf has 

 the same effect. While the animal upon contact with 



