Modifiability in Behavior. 453 



The species of Aiptasia are relatively active and quick-moving 

 anemones. Especially is this true of Aiptasia annulata. If the 

 tip of one of the long tentacles is touched, the whole disk and 

 column shrinks with a sudden quick contraction, reminding one of 

 the rapid contraction of a medusa. To the eye all parts of the 

 body appear to contract at once. Often the disk and column 

 have contracted strongly before the actual contraction wave has 

 made any apparent progress from the tip of the long tentacle to 

 the disk. Certainly in this animal the general contraction does not 

 appear to be due to a spreading of an actual contraction wave 

 from one part of the animal to another, through the actual pulling 

 of one region upon the neighboring one, as it does in Hydra, and 

 according to Torrey ('04), in Sagartia. On the contrary, there 

 seems certainly to exist some rapid method of conduction, suggest- 

 ing nervous action. 



In Aiptasia annulata the use of India ink indicates the presence 

 of cilia driving a current away from the mouth and toward the tip 

 of the tentacles, as in Metridium. 



Aiptasia annulata usually takes crab meat or filter paper soaked 

 in the juices of such meat, but refuses neutral bodies, such as 

 plain filter paper or sand. Aiptasia No. 2, on the other hand, is 

 usually prepared to swallow readily balls of plain filter paper and 

 other small neutral bodies, as well as crab meat. This furnishes 

 opportunity for some interesting comparative experiments. 



Food is taken in the following way: If a small object comes in 

 contact with a tentacle it adheres to the surface, and the tentacle 

 contracts strongly, the whole animal usually contracting at the 

 same time. Then the tentacle bends over and places the food 

 with considerable precision on the mouth. The tentacles near 

 by likewise bend over and are applied to the food body, holding 

 it down against the mouth. This happens even when the body 

 is quite neutral, as plain filter paper, so that the bending of the 

 neighboring tentacles is clearly due to some influence transmitted 

 from the one tentacle in contact with the body. The mouth now 

 opens, the lips protruding a little and seizing the food, while the ten- 

 tacles may release it and bend away. But sometimes the tentacles 

 follow the food into the mouth and their tips remain enclosed for 

 some time. The actual swallowing of the food is mainly due to 

 the activities of the lips and esophagus; it may occur without any 

 intervention of the tentacles, when the food is placed directly on 



