690 DR JAMES W. DAWSON ON 



Bielschowsky's, at every level gave a striking illustration of the extensive persistence 

 of the axis cylinder in not only demyelinated, but in far advanced sclerotic tissue (fig. 427). 

 At not a single level of the many examined were these wanting : they also retained their 

 normal arrangement, calibre, and numbers to a remarkable degree. It must be remembered, 

 however, that the cross-section of the cord was much smaller than normal. Further, the 

 ganglion cells in the demyelinated and sclerotic tissue showed all degrees of pigmenta- 

 tion, atrophy, and disappearance, but very many rounded forms were present, with an 

 otherwise normal structure and chromatophile granule content and arrangement (cf. fig. 410). 

 In Marchi sections, it was possible to recognise a few fat granule cells at almost every level: 

 these were, in most of the segments, confined to the walls of the vessels, and longitudinal 

 sections showed beautifully long stretches of capillaries and transition vessels with a single 

 outer layer of these cells along their whole course or at isolated stretches. Marchi sections 

 thus gave a picture almost as completely negative as the Weigert sections, but there 

 were also present a few isolated areas still in a stage of fat granule cell myelitis. Such 

 areas, as a rule, immediately adjoined the grey matter, especially mesialwards from the 

 posterior horns. 



In the medulla oblongata, pons, and mid-brain, the extensive peri-ventricular and peri- 

 aqueductal sclerosis is well brought out in figs. 76-82. The cranial nuclei, without ex- 

 ception, were involved, and their cells showed marked pigmentation and a degree of atrophy 

 not nearly so marked as those in the anterior horn of the cord. Most of the areas also showed 

 not so advanced a degree of sclerosis, and several areas were present in a stage of fat granule 

 cell myelitis. 



In the brain the areas were present in all stages of fat granule cell formation, and in all 

 degrees of sclerosis, but the majority examined still showed fat granule cells distributed 

 throughout the tissue as well as in the walls of the blood-vessels. The ganglion cells of 

 the cortex throughout not only the areas but in adjoining convolutions, which showed no 

 patch, were found to be surrounded or replaced by satellite cells (fig. 393). Cortical and 

 subcortical areas presented a marked persistence of the axis cylinders. The degree of 

 peri-ventricular sclerosis, the affection of the basal ganglia, the demyelination of long stretches 

 of medullary rays, and the frequent involvement of the cortex, all of which were more 

 marked than in any other case, is well brought out in figs. 70-75. 



The optic nerves-, chiasma, and tracts were completely gelatinous to the naked eye, 

 and as it was evident that they were demyelinated, the tissue was fixed in alcohol for Cajal's 

 stain. It was found that there was an apparently complete persistence of even the finest 

 axis cylinders, and that these were almost unchanged in calibre. Figs. 431 and 432 are 

 taken from one optic nerve and the chiasma respectively. 



The soft cerebral and spinal membranes were thickened and the vessels, both of the 

 meninges and of the nervous tissues, were infiltrated with cells of a lymphocyte type. 



Topographical Distribution of Areas in Weigert Sections. 



Spinal Cord (figs. 83-90). — Areas of sclerosis caused almost a complete transection 

 of the cord at every level, and in no section were more than a few normal fibres present. 

 These, as a rule, occupied the marginal areas and frequently exhibited a marked sym- 

 metrical arrangement (fig. 87). The whole cord from the upper cervical region to the lowest 

 sacral segment seemed to be involved in the sclerosis, and the margins between white and 

 grey matter were invisible. The normal peripheral fibres sometimes formed a continuous 

 band, occupying the region of the posterior or lateral circumference of the cord, or individual 

 small groups of fibres were scattered irregularly along the circumference. The fibres fre- 

 quently stain faintly, and are obviously involved in an early stage of sclerosis. In the 

 eighth cervical segment a larger triangular band of darkly-staining fibres is present on each 



