THE BRAIN. 243 



Placed on its back, it will right itself, but it does not show 

 the usual degree of intelligence and will power. 



Function of the Cerebral Cortex. " Experimentally, 

 we learn that after the removal of the cortex (gray matter) 

 an intelligent animal is reduced to the state of a non-intelli- 

 gent automaton, responding indeed to stimuli, internal as 

 well as external, but failing to interpret the significance of 

 present events in accordance with bygone experience. A 

 brainless dog is stupid ; he may see a bone in front of his 

 eyes without showing signs that he knows the meaning of 

 a bone or the use to which it may be put ; he may hear the 

 crack of a whip, but he no longer shows signs of fear, 

 for he does not remember its sting ; his former purposeful 

 behavior has entirely disappeared ; in short, he has lost 

 memory and judgment." WALLER. 



The Center of Sensations itself Insensible. The 



gray matter of the outside of the brain is the central organ 

 of intelligent sensation and motion. The functions of voli- 

 tion, of consciousness, of intelligence, seem to reside in, or 

 rather to depend upon the activities of, the cells of the 

 gray matter of the convolutions of the cerebrum. This we 

 have learned from experiments on the lower animals, and 

 from accidents and disease in the case of man. All sensa- 

 tion seems to be in the gray matter of the convolutions of 

 the cerebrum, and yet it is itself insensible ; it may be cut 

 and cause no sensation. But when the nerve impulses 

 from the various parts of the body reach the gray matter 

 of the cerebrum they rouse the cells here to an activity 

 that gives us what we call sensation. It is never a sensa- 

 tion until it reaches this part and is properly interpreted. 



Crossed Control of the Body. While each hemisphere 

 mainly controls the muscles of the opposite half of the 



