708 DR JAMES W. DAWSON ON 



figs. 166-173. In the cervical and dorsal segments there is no clearly-defined outline to 

 any of the areas in Weigert staining, and Marchi sections of the adjoining blocks, or Schar- 

 lach R. frozen sections, gave a picture of fat granule cell formation corresponding closely 

 to the extent of the demyelination. Bielschowsky preparations showed that a very large 

 number of the axis cylinders had disappeared and were in a granular condition. In the 

 lower cervical and dorsal cord many normal axis cylinders were retained in the ventral 

 portions of the posterior columns, and in the more isolated and smaller areas found at these 

 levels. The ganglion cells were in all stages of chromatolysis, both in the less and more 

 affected levels : they were not deficient in number, and showed no marked atrophy or pig- 

 mentation. The glia marginal zone was very widened : the nerve roots throughout the 

 cord and of the cauda equina showed a certain rarefaction ; and the membranes a slight 

 degree of cell infiltration. 



Similar changes were found in the areas in the medulla oblongata, pons, and brain, and 

 in the cerebellum. Areas in relation to the hilum of the dentate nucleus (fig. 177) showed 

 beautifully in Marchi sections, the early involvement of the longitudinal fibres passing to 

 the lamellae. 



In the brain no horizontal sections of the hemisphere were cut except at the lower level 

 of the basal ganglia, in close relation to the sub-thalamic region. These sections and those 

 through the mid-brain showed the involvement of the red nucleus on either side (figs. 161- 

 162). Over one hundred blocks of tissue, containing isolated or confluent areas, were taken 

 through, in celloidin and paraffin, from the hemispheres above this level, and these all showed 

 that the areas were in the stage of so-called " fat granule cell myelitis." A few showed a 

 central clearing up of these cells (fig. 182), and an advancing glia fibril formation (figs. 365- 

 366). The peri-ventricular affection, which was very marked, was also at an early stage 

 (fig. 181). Areas were found in every portion of the hemispheres, and especially numerous 

 in relation to the central convolutions. In most of these areas the extension was from 

 subcortical white matter to the deper layers of the cortex : the Betz cells were extensively 

 involved (fig. 387) ; and the vessels in these layers surrounded with fat granule cells. The 

 optic tracts were normal as far as they could be followed, but an early affection of the chiasma 

 and both optic nerves was present (figs. 163-165). The soft membranes of the brain showed 

 a moderate degree of cell infiltration. 



Topographical Distribution. 



Spinal Cord.- — Cervical Enlargement (figs. 167-169). — At the upper part the whole of 

 the posterior columns and the greater part of the left antero-lateral columns are involved 

 in an early area of sclerosis. A few well-marked patches also appear at the two entering 

 posterior root-entry zones and at the extreme lateral border of the cord. As we descend 

 the cord the group of normal fibres in the antero-lateral columns is greatly increased — the 

 principal fibres affected being in the position of, though not strictly limited to, the crossed 

 pyramidal tract. An earlier area is found in the opposite antero-lateral columns — the 

 peripheral cerebellar tracts escaping. At C5 the whole of the right antero-lateral and pos- 

 terior columns are affected — only a few fibres at the base of the anterior median fissure 

 and at the periphery of the posterior roots escaping. Signs of early involvement are also 

 found at the base of the opposite direct and crossed pyramidal tracts. 



In the segment lower one large area is present : this is mostly unilateral and involves 

 posterior and antero-lateral columns. A zone around the periphery, especially wide 

 anteriorly, escapes, while the outer two-thirds of the opposite posterior columns show only 

 slight involvement. The opposite crossed pyramidal and direct cerebellar tracts show early 

 involvement as before. 



At the lower part of the cervical enlargement the greater portion of the cord is involved. 



