CEREBRAL LOCALIZATION 169 



a lesion in Broca's gyrus with aphasia resulting ; 

 they contend that Marie's " quadrilateral " contains 

 the projection fibres of the third frontal convolution, 

 which in their view explains the anarthria ; and they 

 maintain that most of the fifty-seven cases of aphasia 

 in which Broca's convolution was intact were 

 associated with much defect in understanding 

 language spoken or written, and that the lesion was 

 one of the dominant auditory word centre in the 

 temporal lobe, without which Broca's convolution 

 cannot work. 



If it were proved that in cases of apraxia, previously 

 referred to, the lesion was in the first frontal con- 

 volution for the legs, and in the second frontal for 

 the arms, the location of speech just in front of 

 the motor centres for the face and mouth would 

 receive strong support by analogy, but all this is 

 still very uncertain. 



To sum up, we may express current opinion by 

 accepting the existence of a large diffuse centre in 

 the left temporo-parietal region in which recognition 

 of spoken and written language and " internal 

 speech " take place ; when it is seriously damaged 

 these are all lost and the intelligence is impaired. 

 Whether there is a special departure platform in 

 Broca's convolution for uttering speech is uncertain, 

 but probably there is. Lesions of the projection 

 fibres from the cortex ( (?) of Broca's convolution) 

 will cause " anarthria," that is, loss of external but 

 not of internal speech. 



Practical deductions are not to trust aphasia as 

 conclusive localizing evidence of a lesion in the left 



