594 DR JAMES W. DAWSON ON 



histological characters in no way differ from that just described. Fig. 417 shows 

 an involvement of the hypoglossal nucleus. 



Sclerosis of the olivary bodies and of the dentate nuclei leads to a gradual 

 thinning of the lameltae. In numerous specimens there is present a very advanced 

 degree of sclerosis of the fibres entering at the hilum and passing to the grey matter 

 before there is any noticeable involvement of the glia reticulum of the lamellae, 

 unless these are involved in a general extension inwards from the surface of the 

 medulla or ventricle. The ganglion cells (fig. 375), as far as it was possible to 

 interpret their changes, seemed to undergo a gradual and uniform structureless 

 appearance, and to retain a deeply-staining nucleus till the cell body was almost 

 completely atrophied. 



Numerous areas at all stages of development were found in the basal ganglia 

 (figs. 265-267). In the evolution of these areas there is little distinctive to be 

 added. The numerous bundles of parallel nerve fibres which pass through these 

 ganglia and intersect each other frequently give to the resulting glia reticulum a 

 more uniform appearance over short stretches. It was also noted that in such areas 

 it was possible to prove how the process advanced without any relation to any 

 conducting tract of fibres, and simply involved the immediately adjoining tissue 

 bundles in whatever direction they ran. It was found impossible to relate any 

 specific changes in the ganglion cells to the sclerotic process : these underwent a 

 gradual atrophy as the fibril formation became closer. Very large and very 

 numerous spider cells were found in all the early areas, and the fibril development 

 was a very close-meshed one, the sclerosed tissue being formed by a web of very 

 closely arranged fibrils oriented in all directions. The special changes in the 

 branches of the lenticulo-optic and lenticulo-striate vessels will be considered later. 



(b) Cortical Grey Matter. 



It is now well recognised that the cortex is affected in disseminated sclerosis. 

 Before the introduction of the Weigert medullated sheath stain, such areas were often 

 overlooked, and by many their existence was denied. Two deductions may be drawn 

 from this circumstance : the one, that cortical areas are difficult to recognise except 

 with a medullated sheath stain ; the other, the completement of the first, that the 

 glia, axis cylinder, and cell changes in the cortical areas are very slight. Both 

 deductions are, in my experience, justified. A very large number of portions of 

 tissue from the cerebral convolutions, in which macroscopically — after fixation in 

 formalin or after mordanting in bichromate — cortical areas could be distinctly made 

 out, were taken through both for celloidin, paraffin, and frozen sections. In only a 

 small proportion of these could the demyelinated area be recognised in cell stains, 

 even after the most careful comparison with the control Weigert or iron-hsema- 

 toxylin-stiiincd section. The cortical portion, which showed a complete absence of 

 myelin (figs. 298, 385), seemed to show no other change related to the process of 



