CHAP. XXX.] HIGHER CEREBRAL FUNCTIONS. 687 



typical Aphasia, in which little or no mental degradation 

 is to be detected. 



This being true, a general law may provisionally be 

 formulated, as a future working hypothesis : that the ten- 

 dency to mental impairment with Aphasia, and the degree of 

 such impairment, will, other things being equal, increase 

 as lesions of tlie left Hemisphere recede in site from the 

 ' third frontal convolution' and approach the Occipital Lobe. 

 The general doctrine of Marc Dax seems to be justified, 

 whilst Broca's more special localization must be held to 

 hold good only for one particular though very common 

 form of Loss of Speech or, to use the broader and more 

 accurate phraseology, loss of the power of Intellectual 

 Expression. 



The conclusions above arrived at are found to afford a 

 new and quite unlooked for confirmation of the view 

 already announced as to the special frequency with which 

 lesions of the Occipital Eegions of the Hemisphere are 

 apt to be associated with marked mental degradation ; they 

 will also tend to make us appreciate more fully the real 

 validity of the objections raised by some against the 

 doctrine that the posterior part of the left ' third frontal 

 gyrus ' is the region always damaged in cases of Aphasia ; 

 and they may pave the way for new and more exact 

 differential observations, by means of which alone we can 

 expect to make real progress in a task of extreme diffi- 

 culty, in which we are now only breaking ground in a 

 tentative manner that is, in the endeavour to determine 

 what kind of functions are principally carried on in differ- 

 ent regions of the Cerebral Cortex. 



If we have said nothing in regard to the ' localization ' 

 of certain higher Intellectual and Moral Powers, the reason 

 for this will be obvious to all thoughtful readers. No step 



