738 
MR. W. BE VAN LEWIS ON THE COMPARATIVE 
forming the peduncular portion and apex of the wedge (Plate 49, fig. 9, D), contains 
a far greater proportion of fibres than the outer, which are consequently much more 
closely approximated, consisting, as Meynert indicates, of fibres extending from the 
outer segment, as well as fibres originating afresh in itself. The further our exami¬ 
nation of these nuclei by vertical sections extends, the more restricted becomes the 
dimensions of the lenticular nucleus, the mass of the thalamus intervening until on 
a plane with the origin of the pineal peduncles ; its extent is very insignificant,* 
whilst the tail of the caudate nucleus (Plate 49, fig. 10, D) and the stria cornea are 
seen as two small oval bodies, separated from it by the intervening cortical connexions 
of the ganglia. In these posterior planes, vertical sections passing through the tuber 
cinereum will exhibit within the substance of the inferior limbic arc two noteworthy 
structures : first, a compact cylindrical band, consisting of some thirty or more fasciculi 
of medullated fibres, which results from the convergence of fibres from the cortex of 
this region, and is really the temporal extension of the stria cornea ; and secondly, 
just external to it lies a somewhat oval nuclear grey body, the tail-like prolongation 
of the caudate nucleus (Plate 49, fig. 10, C). In sections through the hemispheres 
at that site where the retiring optic tracts are concealed betwixt the crus cerebri and 
hemisphere, the stria cornea will appear to a certain extent of their course cut length¬ 
wise and entering the substance of the limbic lobe external to the optic tract (Plate 49, 
fig. 10, E). 
Coronal projections to the motor ganglia and interned capsule .—Traced from the 
cortex down-wards it is found that the wdiole marginal aspect of the hemisphere at the 
vertex and for a certain distance outside the median line, constitutes the area whence 
the coronal radiations arise which converge to the internal capsule and corpus striatum 
below. Upon arriving at the centric pole of the corpus striatum, the fibres form a 
dense projection mass, which in the form of small fasciculi spread out and almost 
completely enfold the upper and outer aspect of this ganglion, the innermost series 
entering the ganglion direct, the outer fasciculi proceeding along the arched surface of the 
lenticular nucleus to enter it at its outer aspect, whilst the intermediate fibres terminate 
at various points along the intervening surface (Plate 49, fig. 10, A). The receiving 
surface or centric pole of the striate body is therefore a very extensive one, being 
constituted by the whole of its upper and greater part of its outer aspect. The above 
description of its cortical connexions holds good only as regards that region where the 
centric pole of these ganglia attains its greatest height, viz.: anterior to the thalamus 
where the corpora striata lie in closer contiguity. To study its exact distribution a 
series of vertical sections of the brain of the Eat should be examined at different 
planes from before backwards. Thus, in regions of the septum lucidum, in front of 
the anterior commissure, we find the innermost fasciculi of the projection mass where 
they leave the ganglia only 2 mm. distant from the marginal angle of the hemisphere. 
* Vide Plate 49, fig. 10, between A and B. 
