592 NERVOUS SYSTEM 



the anatomical arrangement of the arteries, which seem to furnish 

 a greater quantity of blood to the left hemisphere, it is evident that so 

 far as voluntary movements are concerned, the right hand, foot, eye etc., 

 are used in preference to the left, and that the motor operations of the 

 left hemisphere are superior in activity to those of the right. Bateman 

 has quoted two cases of aphasia dependent on lesion of the right side 

 of the brain, and consequent left hemiplegia, in which the persons were 

 left-handed ; and these, few as they are, are important, as showing that 

 a person may use the right side of the brain in speech, as in the other 

 motor acts. 



Broadbent has reported an examination of the encephalon of a deaf 

 and dumb woman. In this case the brain was found to be of about the 

 usual weight, but the left third frontal convolution was of " comparatively 

 small size and simple character." 



Taking into consideration all the pathological facts bearing on the 

 question, it seems certain that in the great majority of persons the organ 

 or part presiding over the faculty of language is situated on the left 

 side, at or near the third frontal convolution and the island of Reil, 

 mainly in the parts supplied by the middle cerebral artery. In some 

 few instances the organ seems to be in the corresponding part on the 

 right side. It is possible that originally both sides preside over speech, 

 and the superiority of the left side of the brain over the right and its 

 more constant use by preference in right-handed persons may lead to 

 a gradual abolition of the action of the right side of the brain, in con- 

 nection with speech, simply from disuse. This view, however, is purely 

 hypothetical. In some cases of aphasia from lesion of the speech- 

 centre in the left hemisphere, recovery takes place, and occasionally 

 " speech has been again lost when a fresh lesion occurred in this part 

 of the right hemisphere " (Cowers). In the ataxic form of aphasia, the 

 idea and memory of words remain, and there is loss of speech simply 

 from inability to coordinate the muscles concerned in articulate lan- 

 guage. Patients affected in this way can not speak but can write with 

 ease and correctness. In the amnesic form of the disease, the idea and 

 memory of language are lost ; patients can not speak, and are affected 

 with agraphia, or inability to write. The motor tracts from the centre 

 for speech pass to the anterior portion of the posterior division of the 

 internal capsule and thence through the left crus, into the pons Varolii^ 

 where they decussate and go to the right side of the bulb. 



Recently the curious fact has been noted that in the deaf and dumb, 

 who use a sign-language made with the fingers, lesion of the speech- 

 centre is attended with aphasia, in which the power of expressing ideas 

 by means of the sign-language is lost. 



