ANIMAL BEHAVIOUR 181 



suffices for the potassium pill rushing about on the surface 

 of the water. 



The Amoeba encounters a hurtful stimulating influence 

 affecting part of the cell; it withdraws the stimulated part, 

 and that is related to the localisation of the influence. But 

 it proceeds to send forth a finger-like process of its living 

 matter in a new direction, and the issue of this is determined 

 by internal conditions. " If the new direction of movement 

 leads to further stimulation, a new trial is made. Such 

 trials are repeated till either there is no further stimulation, 

 or if it is not possible to escape completely, until the stimu- 

 lation falls on the posterior end, and the animal is retracted 

 directly from the source of stimulation " (Jennings, 1906, 

 p. 22). The importance of this is great. A direction is 

 taken because it relieves the Amceba from hurtful stimula- 

 tion. There is, Jennings says, " selection from among the 

 conditions produced by varied movements ". " Thus the 

 behaviour of Amoeba is directly adaptive ; it tends to preserve 

 the life of the animal and to aid it in carrying on its normal 

 activities" (p. 23). 



" The writer is thoroughly convinced, after long study 

 of the behaviour of this organism, that if Amoeba were a 

 large animal, so as to come within the everyday experience 

 of human beings, its behaviour would at once call forth the 

 attribution to it of states of pleasure and pain, of hunger, 

 desire, and the like, on precisely the same basis as we 

 attribute these things to the dog. This natural recognition 

 is exactly what Miinsterberg (Grundziige der Psychologic, 

 Bd. L, 1900) has emphasised as the test of a subject. In 

 conducting objective investigations we train ourselves to sup- 

 press this impression, but thorough investigation tends to 

 restore it stronger than at first" (p. 336). 



