FUNCTIONS OF THE CEREBRUM. 535 



functions, there is no evidence whatever. But it appears 

 that, for all but its highest intellectual acts, one of the 

 cerebral hemispheres is sufficient. For numerous cases 

 are recorded in which no mental defect was observed, 

 although one cerebral hemisphere was so disorganized or 

 atrophied that it could not be supposed capable of dis- 

 charging its functions. The remaining hemisphere was, 

 in these cases, adequate to the functions generally dis- 

 charged by both ; but the mind does not seem in any of 

 these cases to have been tested in very high intellectual 

 exercises ; so that it is not certain that one hemisphere 

 will suffice for these. In general, the mind combines, as 

 one sensation, the impressions which it derives from one 

 object through both hemispheres, and the ideas to which 

 the two such impressions give rise are single. 



In relation to common sensation and the effort of the 

 will, the impressions to and from the hemispheres of the 

 brain are carried across the middle line ; so that in destruc- 

 tion or compression of either hemisphere, whatever effects 

 are produced in loss of sensation or voluntary motion, are 

 observed on the side of the body opposite to that on which 

 the brain is injured, 



In speaking of the cerebral hemispheres as the so-called 

 organs of the mind, they have been regarded as if they 

 were single organs, of which all parts are equally appro- 

 priate for the exercise of each of the mental faculties. But 

 it is possible that each faculty has a special portion of the 

 brain appropriated to it as its proper organ. For this 

 theory the principal evidences among those collected by 

 Drs. Grail and Spurzheim are as follows : i. That it is in 

 accordance with the physiology of the other compound 

 organs or systems in the body, in which each part has its 

 special function ; as, for example, of the digestive system, 

 in which the stomach, liver, and other organs perform each 

 their separate share in the general process of the digestion 

 of the food. 2. That in different individuals, the several 



