Modifiabihty in Behavior. 449 



specimen, the tentacles immediately surrounding it (including 

 many not in contact with it) begin suddenly to wave back and 

 forth. After an instant this usually ceases, and all is absolutely 

 quiet for a few seconds. Then the movement begins again. 

 All the tentacles that in their waving motion come in contact with 

 the food, bend over against it and shrink, in such a way as to 

 hold it down against the disk. Now that portion of the disk 

 bearing the food begins to sink inward, by a folding of the surface. 

 The mouth, which may be 4 or 5 cm. distant, begins to open, 

 and the walls of the esophagus protrude from the mouth as large 

 bladdery lobes. The region between the mouth and the food 

 body begins to contract, the tentacles borne here collapsing and 

 almost completely effacing themselves. By this contraction the 

 mouth and food approach each other, the intervening region 

 disappearing. Meanwhile other parts of the disk swell and their 

 tentacles become plump and enlarged; this appears to be a 

 secondary phenomenon due to the squeezing of the internal 

 fluid from the contracted region to other parts. The esophageal 

 lobes increase in size, becoming 2 to 4 cm. long, and half as 

 thick; they extend toward the food, finally reaching it. By the 

 contractions and expansions already mentioned the mouth may 

 be moved from the center of a disk 10 cm. in diameter to within 

 I cm. of the edge. By this time mouth and food may be hidden 

 beneath the surface of the contracted disk, though in other cases 

 they lie on the surface in plain view. Now the esophageal lobes 

 extend over and around the food, while the tentacles progressively 

 withdraw from it until the food body is lying on the contracted 

 portion of the disk, completely covered by the esophageal lobes. 

 Next that part of the disk beneath the food withdraws, involving 

 an enlargement and further displacement of the mouth, till there 

 is nothing beneath the food body, and it is pressed by the 

 esophageal lobes into the internal cavity. The whole reaction is 

 thus very complex. 



Twenty or more pieces of crab, including entire large append- 

 ages, may thus be successively taken, till the body of the anemone 

 has become a mere stretched sack full of crab appendages. But 

 in the later reactions of a series the process of food-taking becomes 

 much slower, the animal seeming to become gradually satiated. 

 The food may be taken by the tentacles and held for a long time 

 before it is finally moved to the mouth. In other cases the ten- 



