152 BRAINS OF RATS AND MEN 



ing cortical fields is apparently determined by that 

 of the older thalamic centers. The tactile and audi- 

 tory fibers go out laterally to their cortical projection 

 centers. The visual fibers pass more dorsally. In 

 higher mammals the visual cortical area has been 



loteral nuclei 



lateral geniculate body 



medial goniculptebody 



ditory 



visual 



Fig. 34. — Diagram to illustrate the relations of the thalamic centers 

 for touch, vision, and hearing to the cortical projection centers as seen in 

 horizontal section of a primitive mammal. 



carried farther backward by the enlargement of the 

 posterior pole of the hemisphere. These projection 

 centers comprise nearly all of the neopallium except 

 the frontal pole. Accordingly, motor cortex (primi- 

 tively kinesthetic-motor) is developed within the 

 somesthetic field and in front of it. 



The anatomical analysis of the cerebral cortex of 



