THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 735 



pyramidal tracts. Section is given to illustrate the use of Heidenhain's iron-hsematoxylin stain to bring 

 out myelinated nerve fibres. 



Figs. 292-294. Areas with central blood-vessels : fig. 292, x 30, in external capsule and claustrum ; 

 fig. 293, x 30, in central white matter ; fig. 294, x 13, in central white matter. 



Fig. 295, x 28. Multiple, minute, demyelinated areas in the superficial cortex : sections cut at right 

 angles to the radiating fibres of the cortex. 



Fig. 296, x 50. Radiating fibres passing for an irregular distance into an area. 



Fig. 297, x 10. Bowl-shaped area in the superficial cortex. 



Fig. 298, x 30. Demyelinated area (a) showing no change in the cyto-architecture of the cortex 

 (cf. next figure). 



Fig. 299, x 50. Demyelinated area (a) showing marked cell reaction in the cortex (cf. previous figure). 



Fig. 300, x 30. Slight demyelination (a) of the tangential fibres of the cortex. 



Plate LXVI. 



Figs. 301-312. Special features of early cerebral areas, in which numerous fat granule cells are present, 

 both scattered in the tissue and collected around the blood-vessels. Marchi method. 



Fig. 301, x 20. Area in the central white matter. 



Fig. 302, x 20. Area confined to a medullary ray. 



Fig. 303, x 20. Area involving apex of a medullary ray and passing into the radiations. 



Fig. 304, x 20. Similar area with central (older) portion clearing up. Note that the longitudinally- 

 running vessels, passing from the area, are outlined by fat granule cells. 



Fig. 305, x 20. Narrow area extending along the transition zone of a medullary ray. 



Fig. 306, x 30. Area distinctly limited to the medullary ray in one convolution but passing in another 

 into the radiations. 



Fig. 307, x 20. Involvement of the genu of the corpus callosum. 



Fig. 308, x 30. Peri-ventricular area around the descending horn of the lateral ventricle. 



Fig. 309, x 20. Involvement of the hilum and lamellae of the dentate nucleus of the cerebellum. 



Fig. 310, x 33. Area in central white matter, showing clearing up of the central zone. 



Fig. 311, x 20. Area on the path of the optic radiations (cf. fig. 268). Note that the fat granule 

 cells are confined to the peripheral zone. 



Fig. 312, x 50. Area, almost completely sclerosed, in which a few fat granule cells are present in 

 both central and peripheral zones. 



Plate LXVI I. 



Figs. 313-324. Special features of areas in the spinal cord: figs. 313-315, transverse section; figs. 

 316-323, longitudinal section. Marchi method. 



Fig. 313, x 35. Small area around the vessels of the posterior median fissure (cf. fig. 66); fat granule 

 cells, stained black with the osmic acid, permeate the tissue and surround the capillary and larger vessels. 



Fig. 314, x 100. H.P. of previous figure. 



Fig. 315, x 30. Margin of cord with pia, showing the lateral vessels, with fat granule cells in their 

 adventitial lymphatic sheaths, passing towards the inner layers of the pia, within which they spread in all 

 directions. 



Fig. 316, x 5. Longitudinal interrupted lines of fat granule cells. 



Fig. 317, x 7. Ditto. Paler appearance of part of the section is due to the removal of the fat granule 

 cells in the adventitial lymphatics. 



Fig. 318, x 35. H.P. of previous section, showing these cells in longitudinal rows. 



Figs. 319-323. Evolution of the Marchi changes, in the nerve fibre, which lead to the formation of the 

 fat granule cells; early change frequently a darkening of the myelin (fig. 319, x 50) ; early degeneration 

 in the form of rows of small globules (figs. 320-322, x 30); gradual appearance of fat granule cells (fig. 

 323, x 200). 



Fig. 324, x 40. Degeneration in the sciatic nerve in Case I. 



