CiiAP. XXX] HIGHER CEREBRAL FUNCTIONS. 67.*^ 



In 1836 Dr. Marc Dax called attention to the great 

 frequency of loss of Speech in association with right 

 rather than with left-sided Paralysis. The title of his 

 essay was this : — *' Lesions of the left half of the Brain 

 coinciding with the loss of memory of the Signs of 

 Thought." * In support of this view that loss of Speech 

 depended especially upon lesions of the left half of the 

 Brain, Dr. Dax brought forward 140 observations. 



But in 1831, Brocaf went still further. Whilst affirm- 

 ing, with Dr. Marc Dax, that the left Hemisphere was 

 the one principally concerned with articulate Speech, ho 

 precisely defined the seat of lesion in that condition which 

 we now call Aphasia as "the posterior part of the third 

 frontal convolution of the left hemisphere.'* 



This view, originally based upon a very small number 

 of cases, was received at first with the greatest surprise and 

 scepticism. It was thought by many to be most improbable 

 that such a faculty as Speech should depend upon the in- 

 tegrity of one small portion of only one of the two Cerebral 

 Hemispheres. Yet by reason of the observations which 

 have accumulated during the last eighteen years, it is now 

 admitted by most of those who are best entitled to judge, 

 that Broca's localization is in a certain sense correct, and 

 that in the instances of real typical Aphasia the lesion is, 

 in a large majority of cases, found to involve the posterior 

 part of the third frontal gyrus on the left side, or else the 

 immediately subjacent white substance intervening between 

 this convolution and the Corpus Striatum. The reason why 

 lesions in other parts may, according to their situation, 

 either occasionally or invariably lead to a more or less 

 similar Speechless condition, is a question upon which we 

 shall hope to throw additional light in this chapter. 



* Republished in the " Gaz. Hebdomad.," April 28, 1865. 

 f " Bulletin de la Soc. Anatom.," Aug. and ISTov., 1801. 



