Instinctive Movements of Amoeba 25 



reference to this performance that it is difficult 

 to conceive each phase of action of the pursuer 

 to be completely determined by a simple pre- 

 sent stimulus. For example . . . after Amoeba 

 b had escaped completely and was quite 

 separate from Amoeba c, the latter reversed its 

 course and recaptured b. What determines the 

 behaviour of c at this point ? If we can imagine 

 all external physical and chemical conditions to 

 remain the same with the two Amoebae in the 

 same relative position, but suppose at the same 

 time that Amoeba c has never had the experi- 

 ence of possessing b, would its action be the 

 same? Would it reverse its movements, take 

 in b, then return on its former course ? " One 

 who sees the behaviour as it occurs hardly resists 

 the conviction that the action at this point is 

 partly determined by the change in c, due to 

 the former possession of b, so that the beha- 

 viour is not purely reflex, but partly the result 

 of memory." l 



1 Behaviour of Lower Organisms, by H. S. Jennings, p. 24. 

 New York, 1906. 



Prof. W. B. Hardy, when discussing the nature of the move- 

 ments made by Amoebae, observes : "They manifest discrimination, 

 imperfect no doubt, but as the choice is beneficial it contains an 

 element of purpose." Science Progress, October, 1906, p. 182. 



