OF THE GYRUS MARGIHALTS AYD GYRUS FORNICATUS IN MONKEUS. 
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The part of the capsule along the inner border is occupied by tlie fibi’es from the 
gyrus marginalis (diagr. 2), as is proved by the fact that when the entire motor 
area (including the gyrus marginalis) is removed, the whole width of the internal 
capsule is degenerated (diagr. 3), although the inner border never appears so 
completely degenerated as the outer. 
Diagram 2. 
Horizontal section through one hemisphere showing the position of degeneration following 
removal of the gyrus marginalis. 
Diagram 3. 
Frontal section through brain, showing diagrammatically the coui’se, through internal capsule, taken by 
degeneration following lesions in both the outer and mesial motor surface.* 
Diagram 4. 
' Diagrammatic representation of the degeneration in the crusta. 
In the crusta, the degeneration occupies the middle third (diagr. 4), and little 
difierence in appearance can be seen between that following an exteriicd motor 
(exclusive of gyrus marginalis), and that following a complete motor lesion ; except 
that after removal of the external motor area only, the degeneration is not so great 
along the dorsal as along the ventral border of the crusta. 
In the medulla the whole area of the pyramid is degenerated in those cases where 
* The course of the fibres from the mesial surface is represented by darker shading than that of those 
from the external motor surface. 
