226 BEHAVIOR OF THE LOWER ORGANISMS 



on the internal processes. An Aiptasia (species undetermined), studied 

 by the present author, continued to take filter paper till the body was a 

 swollen sack, and pieces of the paper were repeatedly disgorged. But 

 new pieces, and even those that had just been disgorged, were readily 

 swallowed when apphed to the disk. But when specimens of this 

 Aiptasia were fed considerable quantities of meat, they refused to take 

 either more meat or paper. 



The reactions of well-fed sea anemones dififer in many other ways 

 from those of hungry specimens. They are much less inclined to react 

 to stimuh of all sorts. A disturbance in the water, or a touch with a 

 needle, that would produce a strong contraction in the hungry animal, 

 often causes no reaction whatever in the satiated specimen. A much 

 stronger solution of any given chemical is required to produce contrac- 

 tion than in the well-fed individual. If we should attempt to determine 

 the strength of a given chemical that caused contraction in Aiptasia, we 

 should get totally different results, according as we employed specimens 

 that were very hungry, or only moderately hungry, or thoroughly satiated. 



Another factor influencing the food reactions of the sea anemone is 

 fatigue, and the effects due to this are easily mistaken for phenomena 

 of a different character. If the tentacles of a certain region of the disk 

 of Metridium are given many pieces of food, one after the other, they 

 refuse after a time to take the food, though the other tentacles will still 

 take food readily. In taking food very large quantities of mucus are 

 produced, and it is not surprising that many rapid repetitions of this 

 process exhaust the tentacles. If they are allowed to rest five to ten 

 minutes, they usually take food as at first. 



As the fatigue comes on, the tentacles first cease to react to weak 

 stimuli, such as are produced by plain paper, or paper soaked in meat 

 juice ; later to strong stimuli, such as that produced by meat. If meat 

 and paper are given in alternation, the tentacles will thus at first take 

 both ; then they come to refuse the paper, while the meat is still taken. 

 Later they come to refuse the meat also. 



The reaction to food varies also with certain other conditions. In 

 Metridium and Aiptasia the following is often observed: A specimen 

 refuses to take bits of filter paper, though it still takes meat. After it 

 has thus refused paper, two or three pieces of meat are given in succes- 

 sion, and taken readily. Now the bit of paper is placed again on the 

 disk, and it too is swallowed. Clearly, the uninterrupted taking of a 

 number of pieces of meat changes the physiological condition in some 

 way, preparing the animal for the taking of any object with which it 

 comes in contact. One cannot fail to note the parallelism with what 

 occurs in higher animals under similar conditions. 



