CHAPTER V 



CEREBRAL CORTEX AND 

 CORPUS STRIATUM 



The odors borne by the air are the source oj so many and 

 varied forms of information or clues regarding the environ- 

 ment of a land animal^ not only with reference to food but 

 with reference to all its external relations^ that the expansion 

 of the pallium for correlation of tactual^ visual^ auditory and 

 proprioceptive impressions with one another demands a co- 

 ordinate develop7nent of centers for the correlation of all these 

 with olfactory impressions. The lateral olfactory area, though 

 it elongated pari passu with the general pallium^ was not 

 equal to this task without further development and differentia- 

 tion. 



— J. B. Johnston 



COMPARISON of the normal behavior of 

 fishes and amphibians where both corpus 

 striatum and cortex are rudimentary, birds 

 where the striatum complex is enormously developed 

 but cortex is very deficient, reptiles with large stria- 

 tum and small but well-defined cortex, and mammals 

 where the cortex is progressively amplified clearly 

 shows that the striatum complex and thalamus are 

 enlarged in proportion to the complexity of the innate 

 and instinctive behavior and that the cortex is en- 

 larged in proportion to individual initiative, docility, 

 and inventiveness. 



Attempts to control these observations experi- 



92 



