450 H. S. yennings. 



tacles do not react for some minutes, the food lying on the disk 

 undisturbed, until finally it is slowly taken. Sometimes there is 

 an interesting combination of the positive food reaction and the 

 negative reaction (to be described later). The food is taken by 

 the tentacles and carried very slowly to the mouth, in the way 

 above described, while the mouth opens and the esophageal lobes 

 are protruded. But when the food body reaches the lobes, or 

 sometimes before, the process stops. The food is released by 

 the tentacles, and is finally carried away and rejected, in the way 

 to be described. Finally, when the animal seems fully satiated, 

 the piece of crab meat may be rejected as soon as it comes in 

 contact with the disk. But after one or more pieces have been 

 rejected one may sometimes see another piece accepted. The 

 internal state is in a condition of most unstable equilibrium, and 

 may easily incline toward the positive or the negative reaction. 



Thus it is clear that in Stoichactis the reaction to a given 

 stimulus is by no means a set, invariable property of the organism, 

 but depends on the state of the internal processes. To the same 

 stimulus we may get a quick positive reaction or a quick negative 

 reaction; a slow and deferred positive reaction or a combination 

 of the positive and negative reactions. 



Peculiar effects are observed when several pieces of meat are 

 placed at the same time on different parts of the disk. If the 

 animal is hungry all are carried to the mouth; the entire disk 

 folds inward and the pieces are swallowed simultaneously or 

 successively. I have seen six pieces, placed as far apart on the 

 large disk as possible, thus ingested. When the animal is less 

 hungry the results are different. In some cases, when two pieces 

 of meat are placed on the disk, one is swallowed while the other 

 is rejected. If the rejected piece is again placed on the disk 

 after the first piece has been disposed of, it will sometimes be 

 swallowed. 



Adding new pieces while swallowing is in progress often pro- 

 duces interference. Thus, in one case two pieces of meat, a and b, 

 were placed near opposite edges of the disk. Both began to 

 approach the mouth in the usual food reaction. Now two new 

 pieces, c and d, were placed near the edge midway between a and b. 

 Thereupon the reaction to a and b ceased, while d was transported 

 to the edge of the disk (about 2 cm.) and dropped off. Now the 

 food reaction was resumed, a, b and c traveling tow^ard the mouth. 



