ix] IntcnnciUdtc I'rcct'iitral Area '2'2\ 



Summing up what has been written in the foregoing paragraphs we find that it is 

 possible to determine the limits and extent of the strip of cortex to which I have given 

 the name "intermediate precentral " by no less than three methods, viz., by experimentation, 

 by developmental investigation, and by histological examination in the adult condition. And 

 although, if we except the results of experiment, this does not bring us much nearer our 

 explanation of its function, still the coincidence of results is full of suggestion, particularly 

 when considered along with what we already know of the contiguous " precentral " area 

 prnpiT, and above all when taken in conjunction with the teachings of clinical medicine. 

 Having also seen that this field has important associations and connections, the ground is 

 now cleared for the further pursuit of evidence which will help to prove that its enveloping 

 cortex is specially designed for the control of skilled movements of an associated kind. 



MOTOR APHASIA. 



In view ot my thesis, the most suggestive fact brought out by histology is that the 

 " intermediate precentral " field embraces the classical area which we associate with the name 

 of Broca, the centre for speech, the centre for a faculty which is a skilled movement in 

 the highest degree. We can now discuss this function, and while I must digress to 

 a certain extent to do this I would point out that I do not pi'opose to give a full analysis 

 of the highly developed sensori-motor combination involved in the faculty of speech ; I shall 

 not follow up the complex theories expressed by authorities on this subject, and I shall pass 

 over the various associative and perceptive components supposed to combine in perfecting 

 this function, in order that my remarks may be confined to the motor element in the faculty 

 and to the localisation of the same component, and that the thread of my argument may 

 not be completely broken. 



Since the year 1861 when Broca published his cases of motor aphasia and indicated 

 the association between the power of articulate speech and the posterior part the pars 

 basilaris of the left inferior frontal convolution, numerous cases of a confirmatory nature 

 have been recorded, all proving that here we have an exceedingly vulnerable area. But 

 although it is established beyond doubt that a maximum effect is produced by a minimum 

 lesion in this situation, it is not yet proved with equal clearness and with a sufficient 

 degree of exactitude upon what structure, what particular collection of neurones, the integrity 

 of the high motor mechanism involved in articulate speech essentially rests. In plainer 

 terms, in the numerous cases of motor aphasia resulting from beautifully localised lesions 

 which have been recorded, and in the instances which many of us have seen in our own 

 practice, it is not known whether destruction of the cortex, and of the cortex only, of the 

 pars basilaris has been the essential lesion in the production of the speech defect, or whether 

 it has been due to interruption of subjacent associating or centrifugal neurones, and in what 

 degree either of these has shared in bringing about the disability ; in short the essential 

 link in this mechanism still remains to be decided. 



Recalling what we have learned from experiment and clinical experience concerning 

 localisation of the cortical elements primarily governing movements of the larynx, tongue, 

 mouth, and lips, we may assume, and I think reasonably, that as in the anthropoid ape the 

 elements I have named are deposited in the ascending frontal gyrus in the precincts of 

 the lower end of the fissure of Rolando, so is it also in the human being. But on 

 topographical and clinical grounds we know that this particular part does not represent the 



