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E. Lindon Mellus 2 
posterior segment, but from this level downward they are passing into 
the thalamus faster than their places are taken by other degenerated 
fibers coming from the frontal lobe, so that below this level the amount 
of degeneration in the posterior segment of the internal capsule is con- 
stantly diminishing and has entirely disappeared when we reach the crus. 
These coarse fibers come apparently from the cortical area just in front 
of the external wound, corresponding to the center for the head and 
eye movements. Notwithstanding the extensive character of the lesion 
it is only in the lower levels of the external wound (studying the sections 
from above downward) that any considerable amount of degeneration 
ean be traced from the wound backward. In the plane in which these 
sections were cut the lower extremity of the external wound corresponds 
to the lower extremity of the fissure of Rolando, the development of the 
anterior segment of the internal capsule and the appearance in the sec- 
tion of the foramen of Monro (Fig. 3). Degenerated fibers appear in the 
first bundles going to form the anterior segment and increase rapidly in 
number from above downward. ‘The coarse and fine fibers gradually 
separate, the fine fibers being grouped upon the mesial side of the anterior 
segment, the coarse upon the external side next the lenticular nucleus. 
As stated above, this separation is barely accomplished when the coarse 
fibers disappear from the anterior segment. From this level downward 
copious fine degeneration passes backward from the lesion through the 
anterior segment until this structure disappears from the section and 
the posterior segment becomes the crus. In all these levels a small 
amount of fine degeneration passes backward from the lesion external to 
the lenticular nucleus in the external capsule to come to an end in the 
upper posterior portion of the superior temporal convolution. Although 
some of these fibers pass obliquely through the claustrum from the cap- 
sula extrema to the capsula externa, and vice versa, they do not ap- 
parently terminate in the claustrum. In lower levels (Figs. 6-9) the fibers 
passing backward, by way of the external capsule, turn around or break 
through the posterior angle of the lenticular nucleus, after which it 
becomes difficult to follow them with certainty, as they get mixed up with 
a lot of degenerated fibers coming from an area of softening in the 
splenium of the corpus callosum. <A few fibers appear to run backward 
toward the occipital lobe in the optic radiation, but the majority seem 
to pass into and through the posterior segment of the internal capsule, 
and to end, in the sub-thalamic levels of the capsule, in the external 
geniculate body and the superior colliculus. 
The coarse fibers, above alluded to, coming from the frontal lobe and 
