716 DR JAMES W. DAWSON ON 



median fissure as a broad band, which is surrounded by a zone of lighter staining : and 

 further areas involve the other anterior horn, part of the an tero -lateral column, and the 

 posterior horn on the same side. At a slightly lower level we find a complete transection 

 posterior to a line drawn horizontally across the cord at the level of the base of the anterior 

 fissure. At a lower level the sclerosis ' affects the whole of one-half of the cord, except the 

 anterior third, part of the opposite posterior column, and then stretches as a broad band 

 diagonally across the grey matter of the opposite side to involve the part of the corresponding 

 antero -lateral column. At the next segment the whole of the former severely-affected 

 half of the cord is involved — except a few peripheral anterior and lateral fibres — and the 

 sclerosis advances on the opposite side uniformly as far as a line drawn antero -posteriorly 

 at the outer margin of the anterior horn. At D8 one-half of the cord is again deeply sclerosed, 

 and the opposite side shows evidence of early involvement. At D9 the sclerosis is now much 

 less marked : one small peri-central area and an early degree of sclerosis in one antero- 

 lateral column being alone present. At D10 the same picture is presented, but the antero- 

 lateral area is more evident. At Dll there is again considerable involvement : one-half 

 of the cord is more or less sclerosed, except a peripheral zone, and at D12 two dense areas 

 occur : one in the posterior columns, the other an irregularly-outlined patch which involves 

 a great part of the grey matter on one side and the base of the anterior horn on the opposite. 



Lumbar Region (figs. 215-216). — The first lumbar segment is practically normal. L2, 

 at its upper part, is also normal, but at the lower levels small areas lie peri-centrally and in 

 the substantia gelatinosa Rolandi on both sides. In L3 these areas are all more definite 

 and larger, and the posterior and lateral columns on one side show early involvement : at 

 the lower levels of this segment minute areas appear also at the lateral margin of one anterior 

 horn and along the posterior median fissure. In L4 the early involvement seen in the pre- 

 vious segment has become a large definitely demyelinated area, which occupies the whole 

 of one-half of the section — with the exception of posterior and antero -lateral broad peri- 

 pheral zones — and stretches across the middle line to involve the inner portions of the anterior 

 and posterior horns and a corresponding portion of anterior and posterior column fibres. 



Sacral Region (fig. 217). — As this area is traced downwards through L5, it becomes very 

 irregular in outline, and in Si it forms a broad band on each side of the mesial line : frcuu 

 one side of this band projections pass laterally through the posterior horn and crossed pyra- 

 midal tract to the surface and also anteriorly along the outer aspect of the anterior horn. 

 Two early areas also occur on the opposite half of the cord. In S2 these areas have dis- 

 appeared, and there is little abnormal except a possible lightening of the fibres in the antero- 

 lateral region and a demyelination of the substantia gelatinosa Rolandi. S3 and S4 are 

 normal, with a possibly increased peri-central sclerosis. 



Medulla Oblongata. — In its lower part (fig. 204), about the level of the decussation of 

 the fillet, an early area is present on both sides : this shows a diffuse and light staining, 

 and stretches between the inferior olive and the substantia gelatinosa Rolandi. In the middle 

 of the medulla (fig. 205) similar areas are found in the left restiform body — one towards 

 its centre and one at its posterior surface. 



Pons Varolii (figs. 206-208). — The areas lie mostly in the cerebellar portion. Only a 

 slight involvement is found around the ventricle, but slightly internal to the angles small 

 areas occur which involve the fibres of the Vlllth nerve on both sides. Sclerotic tissue 

 is also closely related to the zone of entry of this nerve : on one side this area is situated 

 immediately on its cerebellar side and is surrounded by a zone of lighter staining which 

 involves the root-entry zone. On the opposite side a similar small early area also involves the 

 fibres of the Vlllth nerve as they pass into the pons. In the upper part of the pons (fig. 207) 

 the section is apparently normal, except for small areas which lie in the pontine grey matter 

 and middle cerebellar peduncle. On the right side a small, dense, somewhat rectangular 

 area is present, slightly internal to the surface : this is situated just at the point where 



