204 BRAINS OF RATS AND MEN 



or any other protoplasm seems to pass from regions of 

 higher excitability and more active metabolism to- 

 ward less active regions, and regions of greater activity 

 are physiologically dominant over regions of lower ac- 

 tivity in so far as these regions are in physiological re- 

 lationship through protoplasmic conductors. 



If now the occipital cortex is bridged into a nerv- 

 ous circuit involved in a brightness-discrimination re- 

 action, the activation of this cortex liberates the local 

 reserves of cortical nervous potential and this field im- 

 mediately becomes the dynamic center of the entire 

 neuronic system involved. The occipital cortex now 

 dominates the entire circuit as its dynamogenic cen- 

 ter, and the removal of this cortex disrupts an equili- 

 brated s^^stem, so that the reaction as a whole fails 

 despite the fact that the thalamic connections are 

 still intact. 



This analysis of the situation is not at all incon- 

 sistent with the fact that the habit can be acquired de 

 novo in the absence of the specific visual cortex of the 

 occipital pole. In this case the energy necessary is 

 drawn from some other source, perhaps wholly tha- 

 lamic, perhaps also from other parts of the cortex than 

 the visual area, or the corpus striatum. But the visual 

 area is evidently normally the most available source 

 of this energy, so that if the behavior pattern is estab- 

 lished with this area intact, its removal disorganizes 

 the pattern. 



On this view one would expect the habit to be more 



