REFLEX AND CONDITIONED ACTION 59 



ously discharged into this center. That which was at 

 first a non-specific diffusion of the auditory stimulus 

 finally comes to be converged into a newly acquired 

 specific conduction path between the auditory field 

 and the origin of the descending salivatory path. 



It is not clear just what is the mechanism of this 

 facilitation and the opening up of a new associational 

 pathway, though there can be little doubt that some- 

 thing of this sort does take place.' There is probably 

 some enduring structural change in the interneuronic 

 connections within the correlation center which fixes 

 and preserves the newly acquired association. The 

 principle most commonly invoked here is the one 

 already mentioned, namely, the capture by an 

 activated path of all available energy from surround- 

 ing parts by reason of its lowered resistance or in- 

 creased permeability to conduction during functional 

 activity, a process which is sometimes called "drain- 

 age'' or "induction" (Sherrington, 1906, p. 206). 

 Thus in the course of the acquisition of the auditory- 

 salivatory conditioned reflex a particular path 

 through the correlation center which has adaptive 

 value in that it eventuates in a feeding reaction is 

 facilitated by use until it is taken to the exclusion 

 of the non-adaptive pathways. The animal has 

 "learned" to salivate when the bell rings. 



^ Hulsey Cason (1925^) has published a general review of the litera- 

 ture of conditioned responses. Two recent articles by the same author 

 (i;25, 1925^) take up some of the theoretic problems of the relation 

 p' conditioned responses to the learning process. 



