736 DR JAMES W. DAWSON ON 



Plate LXVI1I. 



Figs. 325-333. Evolution of an actual sclerotic area, in the posterior columns of the spinal cord, 

 through a stage of fat granule cell formation (fig. 333) ; sections cut in the longitudinal direction of the 

 nerve fibres (pp. 584-585). Of. figs. 1-4. Figs. 325-331, x 200, Heidenhain's iron-haematoxylin ; figs. 

 332-333, x 200, Palladium methyl-violet. a = glia nuclei ; 6 = glia fibrils ; c = fat granule cells ; c? = persistent 

 axis cylinders ; e = blood-vessels. 



Fig. 325. Commencing reaction of all the tissue components. 



Fig. 326. Fat granule cell formation with commencing glia fibril formation. 



Figs. 327-328. Glia cell proliferation with glia fibril formation at the expense of the glia cell protoplasm 

 and protoplasmic processes. 



Figs. 329-330. Increasing glia fibril formation with gradual removal of fat granule cells. 



Figs. 331-333. Advancing and complete sclerosis. 



Figs. 334-336. Variations in the final glia picture. Fig. 334, retained axis cylinders (darker lines) sur- 

 rounded by parallel coursing fine glia fibrils. Methyl-violet, x 200. Fig. 335, undulating lines of glia fibrils 

 and thickened longitudinal vessels. Kulschitsky-Pal and picro-fuchsin, x 50. Fig. 336, sclerosed area with 

 numerous glia nuclei. Haematoxylin and eosine. x 200. 



Plate LXIX. 



Figs. 337-342. Low-power view of the evolution of an actual sclerotic area through stages similar to 

 those in previous plate. Longitudinal sections of the posterior columns of the spinal cord. Van Gieson's 

 stain, x 70. Fig. 341, x 50. Letters a-e, as in previous plate ; /= still myelinated nerve fibres; g = dense 

 sclerotic tissue. 



Fig. 337. Commencing glia proliferation and fat granule cell formation. Note the rows of large proto- 

 plasmic glia cells (fig. 379). 



Fig. 338. Typical picture of "early" area in stage of so-called "fat granule cell myelitis." 



Fig. 339. Increasing glia fibril formation. 



Fig. 340. Gradual condensation and removal of fat granule cells. 



Fig. 341. Advanced sclerosis with their complete removal. 



Fig. 342. Complete sclerosis; tissue consists of longitudinally coursing glia fibrils, blood-vessels, and a 

 few persistent axis cylinders. 



Figs. 343-348. Evolution of an actual sclerotic area in the spinal cord through stages of increasing glia 

 hyperplasia. Transverse sections of the lateral columns. Note no fat granule cells are seen in any of these 

 sections, a = glia nuclei; 6 = glia trabecular ; c = glia reticulum ; d = naked axis cylinders ; e = blood-vesse! ; 

 /= myelinated nerve fibres. 



Fig. 343, x 80, and fig. 346, x 500. Commencing thickening of the glia trabecular and of the fine glia 

 reticulum. Van Gieson's stain. 



Fig. 344, x 50, and fig. 347, x 150. Gradual condensation of this reticulum. Van Gieson's stain. 



Fig. 345, x 150. Condensation and almost fusion of the glia reticulum. Note the still preserved axis 

 cylinders and the enlarged glia cells. Cajal's silver method. 



Fig. 348, x 200. Shows lesser and more advanced degrees of the increasing glia hyperplasia. h = 

 transition zone. Cajal's silver method. 



Plate LXX. 



Figs. 349-354. Evolution of an actual sclerotic area (fig. 354) in the posterior columns of the spinal 

 cord, through a stage of fat granule cell formation ; sections cut transversely to the direction of the nerve 

 fibres (pp. 577-583). Gf. figs. 8-12. Heidenhain's iron-haematoxylin stain. Figs. 349-351, x 370 ; figs. 

 352-354, x 200. a = glia cells ; 6 = glia fibrils ; c = fat granule cells ; d = axis cylinders ; e= " Kielstreifen " ; 

 /= blood-vessels surrounded by layers of fat granule cells; r/ = central canal; h = dense glia tissue ; i = glia 

 fibrils forming whorls. 



Fig. 349. Stage of glia cell proliferation and fat granule cell formation. 



