700 BR JAMES W. DAWSON ON 



in many of the areas, but these were more markedly swollen and faintly stained than in any 

 of the other cases. The areas in the cord, especially in the cervical enlargement, were, as 

 a rule, sharply outlined and, though many areas of " shadow " sclerosis could be traced, 

 these were also less numerous than in some of the other cases. 



Topographical Distribution of Areas. 



Spinal Cord. — Cervical Enlargement (figs. 125-129). — At its upper level several areas are 

 present : one lies in the posterior columns, roughly triangular, with its apex near the central 

 canal : the other patches involve the crossed pyramidal and direct cerebellar tracts on each 

 side ; and a band of sclerotic tissue connects that on the left with the area in the posterior 

 columns. Lighter staining is present in the white matter at the tips of both anterior horns. 

 In the sixth segment the posterior column patch is now limited to an area on each side of 

 the middle line ; the lateral patches are still present — the one extending to involve the 

 whole lateral region of the cord, the other separated from the surface by a narrow zone of 

 normal fibres. The early areas close to the anterior horns are present as before. In the 

 seventh segment the posterior area is very irregular in shape and very extensive. The 

 sclerotic tissue extends anteriorly along the two sides of the anterior median fissure, involv- 

 ing the tissue around the central canal : it then passes dorsally to involve the whole of one 

 posterior horn with all the corresponding white column and the greater part of the opposite 

 posterior columns : it also extends laterally to involve the lateral region on one side. 

 The opposite crossed pyramidal and direct cerebellar tracts show an area commencing at 

 the surface and extending inwards to involve the posterior horn, and an oval area lies in 

 the white matter in front of the right anterior horn. In the eighth segment two areas are 

 present : one in the posterior region, which extends into the lateral portion of the cord, and 

 the area in the opposite crossed pyramidal tract, which is now smaller. At the first dorsal 

 segment the posterior patch is extremely irregular and forms a band which arises in the 

 middle of one posterior column and extends into the middle of the opposite posterior column. 

 It also sends a tongue-like projection in the direction of the central canal, the posterior com- 

 missure of which is sclerosed. This area is connected with a large sclerosed area in the 

 opposite side of the cord by a number of separate strands which pass through the grey matter 

 at the root of the anterior horn. 



Dorsal Region (figs. 130-134). — In the upper dorsal segments the whole of the centre of 

 the cord is occupied by a patch which sends marked projections both dorsally and laterally. 

 At a slightly lower level this becomes broken up into three areas : one on the lateral side 

 of the anterior horn, one in the posterior columns close to the posterior commissure, and 

 the third in the lateral columns, involving crossed pyramidal and direct cerebellar tracts. 

 About the middle dorsal region the most extensive involvement is a patch on both sides of 

 the anterior median fissure, which extends into each anterior and antero -lateral column, 

 obliterating the anterior grey matter on one side and including part of the corresponding 

 posterior horns. In the lower dorsal region four individual areas are present : one, around 

 the central canal, which extends into the posterior columns ; another occupies the whole 

 of the lateral region of the cord ; a third involves the lateral horn and the adjoining grey 

 matter ; and the fourth reaches from the tip of the anterior horn to the periphery of the cord. 

 In the last dorsal segment there is a dense patch in the posterior columns, extending from 

 the central canal backwards : a second dense area is found between the lateral horn and 

 the surface ; and a third, early, area in the crossed pyramidal tract of the opposite side. 



Lumbar Region (figs. 135-138). — In the lumbar region the areas are very few, small, and 

 isolated. In the first segment a narrow ring of sclerosis surrounds the central canal, and 

 there is an indication of early involvement of one crossed pyramidal tract. In the second 

 segment early areas occur in both crossed pyramidal tracts, at the inner anterior angle of 



