684 PROBLEMS IN REGARD TO LOCALIZATION OF 



lings Jackson, believe that a limitation of this kind does 

 obtain. But whilst the writer freely admits that lesions 

 of the left are more likely to be potential than those of 

 the right Hemisphere in the production of such states, it 

 seems to him that both facts and theory tend to negative 

 the idea that similar defects would not be induced by 

 lesions in certain parts of the right Hemisphere. 



It will be found that many such cases are already on 

 record — one of the most typical being that of Marcou, 

 as given by Trousseau (see p. 621). And if we bear in 

 mind that corresponding Perceptive Centres in the two 

 Hemispheres are almost habitually called into simul- 

 taneous activity, and are in structural continuity with 

 one another through the Corpus Callosum, it might be 

 expected that irritative or destructive lesions of the 

 Auditory or the Visual Word-Centres of the right side 

 could scarcely occur without producing distinct derange- 

 ment, at all events for a time, in the functional activity 

 of the similar centres in the left Hemisphere — which, 

 as one is bound to admit, seem to take the lead 

 in the expression of Thought by Speech and Writing. 

 On this very interesting subject much further information 

 is needed, and we have previously (p. 493) had to refer 

 to the doubt that exists as to the extent to which one 

 Hemisphere alone may suffice for ordinary mental activity. 

 It may fairly be expected, perhaps, that Amnesia produced 

 by a lesion of the right side would have a tendency to be 

 more temporary than such a condition when occasioned by 

 similar lesions of the left Hemisphere. 



Finally, another consideration of some importance in 

 connection with * cerebral localizations ' now suggests 

 itself. The condition of Amnesia may merge by insensible 

 gradations into one of Aphasia — so that the latter state, 

 with certain extra peculiarities, may at times result 



