LOCALIZATION OF LEARNING PROCESS 209 



is what we mean by saying that cortical activities are 

 more plastic than subcortical acts, even though the 

 latter may be more quickly established. The func- 

 tions of the cortex must not be evaluated from a single 

 point of view, or with narrow outlook, as would be the 

 case if the rate of establishment of a new habit were 

 used as the only criterion of cortical efficiency. 



Evidence has already been presented (p. 77) that 

 at the inception of well-differentiated cortex it appears 

 as three distinct sheets, each with its own character- 

 istic physiological pattern of subcortical connections. 

 It was pointed out that the distinctive intracortical 

 functions probably involve the interaction of these 

 physiologically diverse cortical areas. With the great 

 increase in the complexity of anatomical and physio- 

 logical specificity of diff"erent cortical areas manifested 

 by even the lowest mammals, the co-operative action 

 of these areas doubtless becomes progressively more 

 significant. In short, some localization of function 

 within the cortex is probably the distinctive feature 

 of normal cortical action, even in its reinforcement 

 and facilitation of lower behavior patterns. The stud- 

 ies of vicarious function (1922), however, do seem to 

 indicate some measure of unlocalizable cortical facili- 

 tation in residual parts of the cortex after removal of 

 the specific areas which are physiologically colligated 

 with particular learning processes. 



The argument as developed here for the functions 

 of the occipital cortex might be applied with but little 



