144 Drs. F. W. Mott and W. D. Halliburton. [Nov. 14, 
ablation ; some few may pass into the internal capsule (vide figs. 1 and 2, 
Plate 3). The degenerated myelin, in the form of black dots and rods, cannot 
be followed farther than the deeper layers of the opposite cortex. Appa- 
rently these fibres either end in the polymorph layer or the inner line of 
Baillarger, where the large psychomotor cells are situated (vide fig. 2, 
Plate 3). (3) A large number of coarse and fine degenerated association 
fibres pass from the lesion to the adjacent uninjured motor cortex; some 
run horizontally into the inter-radial association fibres, the majority, however, 
enter the radiating fibres. We were uncertain whether degenerated associa- 
tion fibres pass to remote regions of the cortex, but some certainly pass to 
the post-central and temporal regions ; there was no degeneration in the pre- 
frontal, hippocampal, or occipital regions. (4) The basal ganglia, especially 
the nucleus caudatus, exhibited great numbers of scattered fine black dots ; 
it is not improbable that this may be accounted for by degenerated collaterals 
given off by the degenerated efferent fibres contained in the internal capsule. 
The degeneration in the lower portions of the central nervous system may 
be most conveniently described by taking separately the individual cases. 
In Lemur 9 (Plate 3, figs. 1 to 8) the lesion involved the head and face 
region. ‘The degenerated peduncular fibres were traced. into the crusta 
of the mid-brain (fig. 5); they are most numerous in its outer and inner 
fourth, and least numerous in the middle two fourths. In Lemurs 7 and 8, 
where limb areas were removed, this relationship was reversed. In Lemur 9, 
_as might be expected, degenerated fibres can be seen leaving the pyramidal 
bundles in the pons, and crossing the median raphe, to arrive at the various 
motor nuclei of the pons, eg., the facial and fifth. This decussation of 
degenerated fibres can be followed all the way down the pons and medulla. 
Only a few degenerated fibres exist in the crossed pyramidal tract of the 
spinal cord in the upper cervical region. (See figs. 3 to 7, Plate 3.) These 
fibres have entirely disappeared in the cervical enlargement (fig. 8). 
In Lemur 7 (Plate 2, figs. 2 to 8), the lesion involved mainly the region 
of the forelimb, and we observe a heavy scattered degeneration in the 
pyramidal system of fibres in the pons and medulla; these fibres do not begin 
to decussate until the mid-portion of the medulla is reached, that is, they 
decussate at a much lower level than in Lemur 9, and at a higher level than 
in Lemur 8, There are no degenerated fibres in the lumbo-sacral region. 
(Fig. 8.) 
In Lemur 8 (Plate 3, figs. 9 to 16) the lesion has involved a part of the 
arm area and the whole of the area of the trunk and lower limb, except that 
lying on the mesial surface of the hemisphere; we observe the heavy pontine 
and medullary degeneration, but the fibres do not begin to decussate until 
