ORGANIC MOVEMENTS 113 



the Eussian physiologist Pawlow with dogs. 1 In all these 

 cases a certain reaction, originally caused by the stimulus 

 A, is in the end called forth by a stimulus B that always 

 was united with A. Whilst in the instance with the crab 

 shortening its way to the water there was a very clear kind 

 of trial, there is not trial in the second experiment. Both 

 experiments offer good instances of the two fundamental 

 characters of our historical basis : in the first it is not only 

 former stimuli but former effects also that are responsible 

 for the specificity of the reaction, in the second it is former 

 stimuli only. 



But the scheme is always the same. 2 



A fine instance of real " training " by means of " lessons ' 

 has been demonstrated by Jennings in his excellent paper 

 on the movements of the starfish, already referred to. 

 " Training " relates to the righting movements in this case ; 

 former stimuli, former reactions, and former effects are 

 equally concerned here. 



And now let us close our long discussions of animal 

 motions with some remarks of a most general character. 



1 But here the process influenced by association is not movement but 

 secretion of the salivary glands. Compare in particular, besides the writings of 

 Pawlow himself, the good article by Boldyreff in Zcitschr. /. d. Ausbau d. 

 Entw.-lehre, vol. i., 1907, Hefte 5 and 6. 



2 Compare our general discussion on pages 63-65. In the experiment de- 

 scribed by Yerkes the term " trial and error" as used by Jennings is quite 

 appropriate : what was at first the effect of a series of trials including errors 

 will become the immediate reaction when the stimulus appears a second 

 time. But it seems to me unjustified to speak of trial and error when there 

 is no objectified experience, and when a series of consecutive various reactions 

 only ceases if a certain state is reached : this state may be a " liked " one, but 

 there is no criterion to discover this in lower animals. What Jennings 

 calls the "resolution of the physiological states one into another" expresses 

 about the same as does my "historical basis of reaction." But Jennings 

 is wrong when he says that this "resolution" only becomes "easier and 



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