98 The Functions of the Postcentral Cortex [CHAP. 



From the evidence brought forward in the preceding section, and the general tenor of my 

 incidental comments thereon, it is patent that I am no believer in the view that the central 

 convolutions have a mixed function, and although in rejecting that belief I feel that I am 

 running the risk of being accused by the physiologist and the clinician of reasoning beyond 

 my facts, I hope that my stand will receive the support of the anatomist. 



Discussing the evidence which has been advanced in favour of the view that the sensory 

 and motor functions are coincident, notice must first be taken of the arguments of those, who 

 have relied upon facts supplied by the study of diseased conditions in the central gyri in 

 the human being, because, for reasons which are apparent, it is to observations on the human 

 subject that we must look for final and conclusive information on this question. Now, although 

 numbers of cases have been recorded in the literature I do not pretend to have read more 

 than a fraction of them of lesions in the Rolandic zone in which the resulting motor paralysis 

 has been definitely associated with sensory disorder in some of its forms, it cannot be denied 

 that recent researches render a very large proportion of these cases useless as evidence either 

 for or against the point under discussion. I refer, of course, to Professors Sherrington and 

 Griinbaum's discovery that the whole of the " so-called " Rolandic zone is not to be included 

 in the motor area, and naturally maintain that before the information obtainable from a study 

 of the results of pathological conditions in the human brain can be regarded as trustworthy, 

 the findings in all previously published cases will have to be thoroughly and carefully revised ; 

 not only so, cases of lesions absolutely confined to one or other of the central gyri and their 

 effects will have to be studied anew and with infinite exactitude ; and as an insufficient period 

 of time has elapsed to allow of a wide propagation of the results of the discovery just referred to, 

 and also to admit of the revision and confirmation necessary to meet it, all our clinico-pathological 

 evidence bearing on the question must for the time being stand in abeyance. Here also I would 

 repeat my caution to the clinico-pathologists, as to the extreme care which must be exercised 

 in the future in selecting cases which are to be utilised for the purpose of tin-owing light on 

 this subject; and for reasons detailed in the chapter on the motor area I would urge them to 

 carry out a painstaking examination of the lesion in the Rolandic area which they believe to 

 have been the source of the previously-observed clinical manifestations ; for clearly it is essential 

 that, if it is to be proved that the anterior central gyrus possesses sensory as well as motor 

 functions, only the effects of lesions strictly confined to that gyrus, and preferably to the 

 cortex alone, can be taken into account ; and if, on the other hand, it is to be proved that 

 the posterior central gyrus has to do with sensation only, the lesion must be similarly confined 

 to this gyrus. 



It would be presumption on my part also to warn clinical observers against arriving at 

 hasty conclusions concerning the sensory effects of such lesions, if there be any, but I take 

 the liberty of quoting on the subject from von Monakow's personal experiences. This accom- 

 plished clinician writes, " that in testing sensation it is essential to carry out not only prolonged, 

 but repeated observations by the most delicate methods, because frequently the sensory changes 

 resulting from a cortical lesion undergo pronounced variations, and in course of time clear up 

 to a remarkable degree." 



Just as it is with the clinical evidence, so also in the case of experimental observations 

 on lower animals, the results which have been set on record in support of the "sensori- 

 motor" hypothesis prove nothing one way or the other; for obviously the wholesale ablations 

 of both central gyri which have been practised must of necessity have occasioned mixed motor 



