THE BRAIN. 



497 



there may be certain areas within which the resistance is such 

 that impulses are usually confined to them, it is also true that, 

 as in the cord, there may be a kind of overflow. Adjacent cells, 

 possibly widely separated cells, may become inTolved. "We shall 

 return to this important subject again, however, as, without 

 recognizing such relationships, it seems to us quite impossible 

 to vmderstand the facts as we find them in the working of the 

 body and the mind. 



•'P''^^,'- ' - 



The Cerebral Cortex. — We may now proceed to inquire what 

 are the functions of the cells of the gray matter covering the 

 surface of the cerebrum. Before the birth of physiology as a 

 32 



