244 BRAINS OF RATS AND MEN 



ord of its incipience in usable form marks just the 

 difference between the explicit and the implicit types 

 of behavior — in brief, the difference between brute 

 and man. Apes and some other higher mammals ap- 

 parently exhibit recognizable stages in this transi- 

 tion. 



Quite apart from such speculative considerations 

 it is clear that the mnemonic functions of the associa- 

 tional cortex are fundamental. The impressionability 

 of this cortex and its retentiveness of patterns once 

 impressed upon it underlie all of its mysterious capaci- 

 ties as the organ of the distinctly human functions, 

 capacities which are clearly recognizable in the anthro- 

 poid apes and which are probably incipient in dogs. 



This more complex organization of the association 

 centers not only enormously increases the flexibility 

 of the action system by permitting a greater variety 

 of types of connection between the various projection 

 centers under present stimulation, but it also brings 

 to bear upon the now acting stimulus complex mem- 

 ory traces of previous successful reactions in similar 

 cases, thus immeasurably broadening the field of 

 efficient correlation — traces which can on occasion be 

 called into play, even in the absence of any present 

 sensory stimulation by changes in internal state. 



One of Kohler's observations shows how impor- 

 tant this retentiveness is in the development of in- 

 ventiveness. Young chimpanzees generally quickly 

 pick up a stick to pull a banana to them that lies just 



