Dr. Foville on the Anatomy of the Brain. 27 



the anterior commissure only unites parts devoted to sensa- 

 tion. 



I shall not insist further on this anatomical proposition, 

 but if you will allow me briefly to add a few physiological 

 deductions, I would say that the fibrous parts intermediate 

 between the internal surface of the convolutions and the an- 

 terior pyramids, appear to me to be simple conductors, as 

 well as those which unite the organs of sensation with the 

 circumference of the gray substance of the convolutions; these 

 transmitting to the muscles the influence of the gray substance 

 which determines their contraction, whilst those convey from 

 the organs of sense to the same gray substance impressions 

 made on the surface of these organs. 



The grey substance of the convolutions appears to me to 

 be the material substratum, by the intervention of which the 

 will directs the movements of the body. For the last twenty 

 years lesions of this substance have been pointed to as those 

 most frequently occurring in the insane, by those physicians 

 who expect to find in the brains of such patients alterations 

 corresponding to the characteristic symptoms of their dis- 

 orders. 



Atrophy of the convolutions, so frequently seen in de- 

 mentia, appears to me to result from disuse of the functions 

 of the gray substance ; then the fibrous matter proceeding 

 from this gray substance becomes atrophied also, just as the 

 optic nerves fall into a state of atrophy in the blind. 



Pathological anatomy furnishes numerous examples of le- 

 sions of the fibrous matter intermediate between the cortical 

 substance of the convolutions and the anterior pyramids. 

 Paralysis of the active organs of motion on the opposite side 

 is generally the consequence. 



The information afforded by pathological anatomy, relative 

 to the effects of lesions affecting the fibrous parts intermediate 

 between the gray substance of the convolutions and the or- 

 gans of sense, is not so clear. This is owing, J imagine, to 

 the communication in the median line between these fibrous 

 parts of opposite sides, and the great number of these parts 

 rendering the complete obstruction of the impressions they 

 are meant to convey, difficult. 



Before summing up these conclusions, relative to the struc- 

 ture and office of some parts of the brain, I should like to say 

 a few words on the relations which the study of the cranium 

 establishes between different regions of this bony case and the 

 corresponding regions of the organ which it incloses. 



If the two frontal eminences are divided horizontally by 

 sawing on a plane perpendicular to their centre, and this sec- 



