CHAPTER XII 

 THE FRONTAL LOBES 



Without an extended discussion of the anatomical details 

 of the central nervous system, we may fall back upon the 

 axiom — agreed to by physiologists, pathologists, and anato- 

 mists — that ^'movements, not muscles, are represented in the 

 cerebral cortex'' 



— F. Wood Jones 



WE have now analyzed as best we can with 

 the data available the learning process 

 and its mechanism in lower vertebrates. 

 We shall next sketch in outline the probable history 

 of the elaboration of this mechanism through the 

 vertebrate series to its culmination in man. The tre- 

 mendous enlargement and complication of this mech- 

 anism as we pass from the highest living brutes to 

 the lowest surviving races of men is indicative of a 

 gap in the phylogenetic series of wide extent — a gap 

 which up until now has been only partially filled by 

 paleontological and archaeological discoveries. No 

 attempt will be made here to outline this unwritten 

 chapter of evolutionary history, but we shall touch 

 very Hghtly upon some of the differences between the 

 organization and functions of the cerebral cortex as 

 we find it in lower mammals and in the higher mem- 

 bers of this class. 



The analysis of the preceding chapters seems to 



