LECTURE IV. 99 



passes above the cerebellum and gradually covers it with its 

 lower surface. A section along the course of the zygomatic 

 arch, dividing the skull, would almost exactly coincide with the 

 under surface of the cerebrum. The cerebellum would not be 

 touched in such a section, as it lies in the part of the occiput 

 covered by the insertions of the muscles of the neck. 



The mass of the cerebrum is insensible ; only the crura and 

 the tubercula quadrigemina are sensitive. In wounds of the 

 head, when the brain is exposed, the surface may be touched 

 or portions removed, without the manifestation of any pain. 

 On the other hand, experiments performed on animals, espe- 

 cially birds, have proved that the cerebrum is manifestly the 

 sole seat of intelligence. Pigeons may be kept ahve for weeks 

 after the removal of the hemispheres. You will find a sum- 

 mary of such experiments in my Physiological Lectures (3rd 

 edition, p. 316). But these phenomena prove that an animal 

 deprived of its brain continues to live, in a deep sleep as it 

 were. The power of motion remains as well as combined 

 muscular action to a limited extent j pain is felt, and certain 

 movements are made to avoid it ; but the animal is undoubt- 

 edly in a state of stupor, in a certain dreamy condition which 

 admits of no consciousness. There is no combination of the 

 sensations to manifest the feelings. The animal, as an ob- 

 server remarks, might die of starvation before a well-filled 

 trough, as the want of food does not induce the motion requi- 

 site for feeding. 



The cerebrum is thus unquestionably the seat of intelligence, 

 consciousness, and will, consequently of all intellectual ac- 

 tivity. The white fibres contained in it serve probably for 

 connecting the individual grey parts ; for they are, like them, 

 insensible. The question now is, whether the different intellec- 

 tual functions are confined to difierent parts of the brain, and 

 if so, to what parts ? 



Experiments on animals furnish, in this respect, only unsatis- 

 factory results. If the hemispheres are removed in shoes, the 

 phenomena of stupor become gradually more manifest. The 

 removal of one entire hemisphere presents no remarkable re- 

 sult ; whence it may be concluded that the remaining hemi- 



H 2 



