624 CEREBRAL CONVOLUTIONS [BOOK in. 



to decide between these two views ; meanwhile it will be well not 

 to consider the latter as the only possible one. 



With this preliminary caution we may now proceed to inquire 

 whether we can attribute different functions to different parts 

 of the cerebral cortex. All the older observers, Flourens and others, 

 agreed that when the cerebral cortex was gradually removed, 

 piece by piece or slice by slice, no obvious effects manifested 

 themselves, either in the intelligence or volition of the animal, 

 when the first small portions were taken away ; but that, as the 

 removal was repeated, the animal became more and more dull and 

 stupid, until at last both intelligence and volition seemed to be entirely 

 lost. It has been frequently observed that in case of wounds of 

 the skull large portions of the brains of men might be removed 

 without any marked effect on the psychical condition of the 

 patients. The brain when exposed was found not to be sensitive ; 

 and ordinary stimuli applied to the surface of the convolutions of 

 animals failed in the hands of most experimenters to produce any 

 clearly recognizable effect. Hence it became very common to deny 

 the existence of any localization of functions in the convolutions of 

 the hemisphere, and to speak of the brain as * acting as a whole,' 

 whatever that might mean. On the other hand, pathological 

 observation seemed clearly to shew that diseased conditions limited 

 to different areas of the convolutions, produced different effects. It 

 was found that in the case of circumscribed lesions confined to 

 parts of the cerebral cortex, the effects whether in the way of 

 paralysis or of convulsive movements, were frequently confined to 

 certain regions of the body or were even limited to particular 

 groups of muscles. One set of phenomena in particular spoke very 

 strongly in favour of definite convolutions, i.e. definite parts of the 

 cerebral cortex having definite functions. In certain cases of cere- 

 bral disease the patient is unable to speak at all or speaks imper- 

 fectly or incorrectly. It is obvious that the failure to speak or to 

 speak properly may be brought about in various ways; the fault 

 may be simply in the tongue or hypoglossal nerve, or it may lie in 

 one or other of the series of central and cerebral processes which 

 issue in coordinate impulses being sent to the organs of speech. 

 Using the word aphasia, as is usually done, in its general sense to 

 denote the partial or complete loss of articulate speech, due to 

 cerebral causes, we may say that aphasia was found to be so closely 

 associated with disease of a definite part of the brain, viz. the 

 posterior portion of the third frontal convolution, Fig. 86 (9) (10), 

 as to afford almost irresistible proof that this particular part of 

 the brain must be specially connected with the faculty of speech. 

 Moreover the disease occurs in so great a majority of cases on one 

 side of the brain only, namely the left (aphasia being frequently a 

 symptom accompanying right hemiplegia, or paralysis of the right 

 side of the body, the disease in such cases affecting other parts of 

 the brain as well), as to suggest the idea that in the act of speech, 



