1878.] 



of the Motor Area of the. Brain. 



47 



frontals presents almost invariably a marked sinuous flexure, the 

 central portion of which often forms a tolerably plump lobule. A 

 large area is represented by the parietal aspect of the upper two- 

 thirds of this region in which the cells are large and numerous, 

 extending beyond the vertex of the convolution (Plate 3, K), but, 

 sloping backwards at a lower level until they finally disappear 

 (Plate 3, M). Thus from the points M to 1ST no groupings of these 

 cells were discoverable. Again, the remaining third of this region, 

 and the portion immediately connected with the second frontal con- 

 volution, show a separate grouping of these great cells (Plate 3, 

 N— 0). The latter group commences posteriorly and spreads beyond 

 the vertex of the convolution. The two separate areas last described 

 (H — M and N — 0) occupy approximately the circles 6 and 7 in Ferrier's 

 figures.* The posterior extremities of the superior and middle frontal 



Fig. 2. Left ascending frontal convolution, seen from the side, including that portion 

 of the two upper frontals (E — S) admitted into the scheme for examination. 

 The letters, as in fig. 1, correspond with those of the scheme (Plate 3) . 



convolutions exhibit a very extensive area of these cells, which, how- 

 ever, rapidly disappear as our sections extend forwards. It is to be 

 observed that this extensive group of cells can be followed back into 

 the ascending frontal convolution, communicating therefore with the 

 series which at the origin of the frontals have been seen to occupy the 

 anterior aspect (Plate 3, R and S). 



To recapitulate, we have presented to us a series of distinct group- 

 ings of these great cells arranged chiefly along the parietal aspect of 

 * Op. cit. Figs. 63 and 65. 



