Modification by Experience 215 



There are many examples of similar behavior in other 

 animals. Hydra, which sometimes displays the phenome- 

 non of adaptation by refusing to react at all to repeated 

 stimulation, in other cases tries first the ordinary negative 

 response of contraction, and later moves away from the region 

 it has been occupying (418). Frandsen found that if the slug 

 Limax maximus has a tentacle touched several times in suc- 

 cession, it at first withdraws the tentacle and turns away from 

 the stimulus. Later, it may move toward and push against 

 the stimulus, and do the same if the touch is on the side of 

 its body, resisting and curving around the obstacle another 

 way, of course, of getting rid of it (135). Preyer, again, 

 observed a very pretty instance of this sort of behavior in the 

 starfish. He slipped a piece of rubber tubing over the middle 

 part of one of the arms of a starfish belonging to a species in 

 which those members are very slender, and found that the 

 animal tried successively various devices to get rid of the 

 foreign body, to wit, the following: rubbing it off against 

 the ground, shaking it off by holding the arm aloft and wav- 

 ing it pendulum-wise in the air, holding the tube against the 

 ground with a neighboring arm and pulling the afflicted arm 

 out, pressing other arms against the tube and pushing it off, 

 and, finally, as a last resort, amputating the arm. This, says 

 Preyer, is intelligence, for the emergency is not one normal to 

 the animal, and it is adapting itself to new conditions (350). 

 It would, however, be demanding too much even from intel- 

 ligence to suppose that the starfish's behavior is entirely 

 new. A human being, capable of ideas, could only, in a 

 similar predicament, "think of," that is, call up, ideas of the 

 behavior which on former occasions somewhat resembling 

 the present had proved effective. Do such cases of the trial 

 of different devices indicate that the animal concerned calls 

 up any kind of idea or image of each device, before putting 



