The Beginnings of Intelligence 127 



responded to a stimulus has become transformed 

 into a different mechanism which may respond more 

 or less readily than before or radically change its 

 method of behavior. 



A striking illustration of varied responses to a 

 given stimulus has been described by Jennings in the 

 sea anemone Stoichactis. If a foreign body is placed 

 upon its disk the anemone tries to rid itself of the 

 object in various ways. The tentacles near the ob- 

 ject collapse and the area between them extends, 

 thus producing a relatively smooth surface so that 

 the waves can readily wash the object away. If this 

 does not occur the region under the object begins to 

 swell, thus rendering the removal of the object still 

 easier. If this reaction is unsuccessful the edge of 

 the disk begins to sink so that a smooth sloping sur- 

 face is formed from which the object can readily 

 slide. Here, as in the case of Stentor, we have an 

 organism capable of reacting in several ways to a 

 given stimulus. What particular reaction is evoked 

 depends upon previous stimulations. 



Modifications of behavior caused by different con- 

 ditions of nutrition are found in the lowest mem- 

 bers of the animal kingdom. Even the white blood 

 cells after they have ingested a number of bacteria 

 refuse to take in more. Whether there is a limit 

 to the appetite of Amoeba has not been determined, 

 but many infusorians such as Stentor, after having 

 swept in a certain amount of food, react to food 

 particles in a quite different way than when in a hun- 



