310 RESEARCHES ON CORTICAL LOCALISATION AND 



similar, though related, modes which in many instances fulfil their 

 purpose in an admirable manner. 



Hence, the histological investigation of a given cerebrum is 

 probably capable of affording a rough criterion of the anatomical 

 basis which subserves, not the actual grade of functional activity, 

 but the possible limits of educdbility of the organ. It may be re- 

 marked that this mode of viewing the subject disposes of the chief 

 objection urged by Bianchi against the doctrine of Flechsig. 



It may therefore be stated that the exact limits of the psycho- 

 motor or Betz cell area, and of the visuo-sensory area, are known 

 beyond doubt, and that their functions have been proved by 

 experimental or histo -pathological methods. As regards the less 

 certainly denned visuo-psychic region, the associational, in contra- 

 distinction to receptive, function of this area has been develop- 

 mentally proved by facts stated earlier in this article. These 

 from a different aspect, that of the evolution of cortical lamina- 

 tion, confirm the doctrine of Flechsig with regard to centres of 

 association and of projection. A similar statement may be made 

 with regard to the well-known, but as yet not precisely defined, 

 prefrontal region of the cortex cerebri (10 of Brodmann). Further, 

 anatomical evidence points to the post-central gyrus or some part 

 of it as the projection area for bodily sensibility, and the recent 

 experiments of Oskar Vogt, who states that ablation of this gyrus 

 in the monkey is followed by ataxy without palsy, have finally 

 proved the truth of this view. There are anatomical grounds for 

 considering that the projection spheres for hearing and for olfactory 

 and gustatory sensations are more or less correctly located, but 

 experimental or histo-pathological proof in these cases is not yet 

 available. With regard to the numerous other areas mapped out 

 by Brodmann and by Campbell, there is little doubt that future 

 research will enable both their exact or variable limits to be 

 determined, and their functions to be finally proved. 



It is ti us possible to make the broad statement that the human 

 cerebral cortex, excluding for the moment the frontal lobes, is 

 histologically differentiate into areas of projection connected with 

 the various senses, each of which areas possesses a zone of cortex 

 connected with or surrounding it, and into further areas which 

 occupy the remainder of the cortex. Reasoning by homology on 

 the truths known with regard to the visuo-sensory and visuo- 

 psychic regions, it is possible to state that the areas of projection 



