CHAP. IL] THE BRAIN. 1117 



place in the cortex. If we accept the view just laid down, 

 we must regard the supereminent activity of the cortex and 

 the characters of the processes taking place in it as due not so 

 much to the intrinsic chemical nature of the nervous substance 

 which is built up into the cortical grey matter as to the fact that 

 impulses are continually streaming into it from all parts of the 

 body, that almost all influences brought to bear on the body 

 make themselves felt by it. To put the matter in a bald way 

 we may ask the question, what would happen in the cortex if, its 

 ordinary nutritive supply remaining as before, it were cut adrift 

 from afferent impulses of all kinds ? We can hardly doubt but 

 that volitional and other psychical processes would soon come to 

 a standstill and consciousness vanish. This is indeed roughly 

 indicated by the remarkable case of a patient, whose almost only 

 communication with the external world was by means of one eye, 

 he being blind of the other eye, deaf of both ears, and suffering 

 from general anesthesia. Whenever the sound eye was closed, he 

 went to sleep. It is further indirectly illustrated by the following 

 experimental result. We have seen ( 654) that a vertical incision 

 carried through the depth of the grey matter around an area does 

 not prevent stimulation of the surface of the area producing the 

 usual movements. But after such an incision the animal suffers a 

 paralysis of the movements connected with the area, like that 

 resulting from the removal of the grey matter of the area ; and 

 the operation is said to be followed by degenerative changes in 

 the area, and degeneration of the pyramidal fibres starting from it. 

 Some of this effect may be due to nutritive changes brought about 

 by injury to the pia mater and division of blood vessels; but it 

 cannot be wholly accounted for in this way ; it appears as if the 

 life of the area is curtailed when its nervous ties are broken. 



We may conclude then that we are not justified in speaking 

 of consciousness or volition, or other psychical processes, even 

 admitting that these fail when the cortex is removed, as being 

 functions of the cortex in the same way that we speak of the 

 functions of other organs ; they are rather functions of the con- 

 nections of the cortex with the other parts of the central nervous 

 system. 



We should add that they are also functions of the connections 

 of the several parts of the cortex with each other. All our 

 knowledge goes to shew that psychical processes are dependent 

 on, or are in some way associated with the cortex ; but whatever 

 classification of psychical functions we adopt, we are wholly unable 

 to make out any localisation of functions, such as we can make 

 out for movements, visual sensations and the like. Even taking 

 the broad and elementary division into " the emotions " and " the 

 intellect," we cannot satisfactorily allot either division to any 

 particular part of the hemisphere. In dogs, removal of particular 

 parts of the hemispheres has indeed been observed to change the 



