THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 627 



white matter with the adjacent anterior and lateral horns but sparing the area 

 occupied by the direct pyramidal tract. A few sections lower this area increased in 

 size and extended mesialwards to the anterior median fissure. A second area, of 

 more complete sclerosis, is now present, involving the columns of Goll along their 

 anterior two-thirds. This area increases very rapidly and soon forms a broad band 

 along each side of the mesial line, both anteriorly and posteriorly, involving grey and 

 white matter indiscriminately. The symmetrical distribution of the sclerosis is here 

 very marked. Slightly lower, the early "shadow" area has almost disappeared, the 

 large mesial area now extends laterally to involve the greater part of the posterior 

 horn and column on one side and the corresponding third of the other side, and a 

 third area has appeared on the opposite side in the crossed pyramidal tract. 



In the third segment four well-marked areas are visible : the largest involves the 

 whole of the right lateral column with the exception of the fibres of Lissauer's tract : 

 on the same side a small triangular area extends outwards from the tip of the 

 anterior horn. On the left side an irregular patch is present in the antero-lateral 

 region, separated from the anterior horn by a narrow zone of normal fibres, while the 

 fourth patch, roughly quadrilateral in outline, is found in the posterior columns and 

 involves the centre of the posterior columns, extending slightly beyond the mesial 

 line on each side. At a slightly lower level, each of these patches extends and leaves 

 the normal tissue in the form of the letter H, while only a few sections lower there is 

 almost a complete transection of the cord. 



A section across the upper part of the cervical enlargement exhibits only a small 

 area, along the periphery of the left antero-lateral region of the cord, where the fibres 

 were unaffected, and even this area had a small patch of sclerosis about the middle. 

 On the opposite side small isolated groups of normal fibres are present near the 

 internal margin of the anterior horn and at the posterior root entry zone. In C6 the 

 previous groups of uninvolved fibres have almost disappeared. On the right side, 

 however, the direct pyramidal tract and the greater portion of the posterior columns 

 are unaffected, and in 07 the normal tissue is increased — the greater part of the 

 posterior columns on both sides being normal, as well as a portion of the right lateral 

 and left anterior columns. In C8, the normal tissue is again much diminished and 

 consists of fibres on either side of the anterior median fissure and a portion of the 

 posterior columns. At a slightly lower level the posterior columns become involved, 

 only a few scattered fibres here and there escaping — the lateral column on one side, 

 and the antero-lateral on the other also escape. In the lowest part of 08, the only 

 lesion is one large patch on one side, limited by the posterior horn of grey matter, 

 extending over the whole antero-lateral portion, but allowing the direct cerebellar 

 tract to escape. 



Dorsal region (figs. 55-58). — In Dl, this patch of sclerosis has spread across to 

 the opposite side, leaving only a small area on the lateral part unaffected. In the 

 third segment only two early areas are found : one on the right side, involving the 



