FUNCTIONS OF THE CEREBRUM. 533 



according to which we can judge ; 2ndly, by which are 

 performed those acts of will, each of which requires a 

 deliberate, however quick, determination ; ^rdly, they are 

 the means of retaining impressions of sensible things, and 

 reproducing them in subjective sensations and ideas; 

 4-thly, they are the medium of the higher emotions and 

 feelings, and of the faculties of judgment, understanding, 

 memory, reflection, induction, and imagination, and others 

 of a like class. 



The evidences that the cerebral hemispheres have the 

 functions indicated above, are chiefly these : I. That any 

 severe injury of them, such as a general concussion, or 

 sudden pressure by apoplexy, may instantly deprive a 

 man of all power of manifesting externally any mental 

 faculty. 2. That in the same general proportion as the 

 higher sensuous mental faculties are developed in the 

 vertebrate animals, and in man at different ages, the more 

 is the size of the cerebral hemispheres developed in com- 

 parison with the rest of the cerebro-spinal system. 3. That 

 no other part of the nervous system bears a corresponding 

 proportion to the development of the mental faculties. 

 4. That congenital and other morbid defects of the cerebral 

 hemispheres are, in general, accompanied with correspond- 

 ing deficiency in the range or power of the intellectual 

 faculties and the higher instincts. 



Respecting the mode in which the brain discharges its 

 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 disorganised 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 



