56 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



an individual history of the performer, certainly nothing 

 like history with regard to the particular stimulus then 

 at work. 



But then historical elements of this sort are entirely 

 absent in another group of phenomena, where at first 

 glance it might possibly seem that they were present. 

 Let us begin with an instance discovered by Jennings 

 in studying the Protozoon Stentor, and already shortly 

 mentioned above. To one and the same mechanical 

 stimulus Stentor first reacted by a simple turning aside, 

 but this reaction did not bring it out of reach of the 

 stimulus; it then reversed the direction of its ciliary 

 movement, and after that contracted itself into its tube, 

 but without success; the stimulus, a falling of powder, 

 continued; then, finally, the Stentor swam away. "We 

 here see three or more different reactions following each 

 other in correspondence to one stimulus. We may say, 

 perhaps, that the following reactions occurred because the 

 first one was not successful, and certainly there is some- 

 thing of an individual historical element in this behaviour ; 

 but, in spite of that, we should prefer not to speak of an 

 action. It is one series of events that occurs here, not one 

 reaction at one time and another reaction, modified by 

 experience, at another ; there is " trial ' perhaps, but no 

 " experience." 



But there is " experience," and therefore action, though 



1 The same holds for the movements of Ophiurids, according to von 

 Uexkuell and Glaser (Journ. exp. Zool. 4, 1907). There is a great variety 

 of reactions, but no "experience." Preyer was right in his description of 

 facts, but not in his interpretation. But in Asterids there exists " experience," 

 besides a great variability of reacting (see the recent memoir of Jennings 

 cited on page 31). 



