702 DR JAMES W. DAWSON ON 



nerve are involved in the sclerosis. The white matter of the cerebellum on both sides shows 

 irregular diffuse areas of " shadow " sclerosis. The dentate nucleus on both sides contains 

 in its hilum early areas, with an additional area of older date on the left side. The medul- 

 lary cores of the vermis are markedly altered. 



Middle Third (fig. 122). — The patches here are mostly small in size and are related to 

 the ventricle. One area of sclerosis extends from the median raphe to one angle of the ven- 

 tricle, and in relation to it a more diffuse " shadow " sclerosis is present. Several other 

 diffuse and dense areas are present in the formatio reticularis on both sides, and one very 

 marked area is present in the intra-medullary root zone of the left Vth nerve. Numerous 

 patches are found in relation to the dentate nuclei, several small ones in the middle peduncle, 

 and several of the cores of the foliee of the cerebellum are cut across by minute patches. 



Upper Third. —Patches, around the aqueduct of Sylvius, pass into the posterior portion 

 of each superior cerebellar peduncle. Numerous smaller areas occur on each side of the 

 raphe, in the formatio reticularis, and a dense area, in front of the superior cerebellar 

 peduncle, obliterates the lateral and part of the mesial fillet. On each side dense areas of 

 sclerosis involve the emerging root zones of the Vth nerve — the one on the right side ex- 

 tending irregularly from it around the surface of the pons into the middle peduncle fibres. 

 Another small area is found in the transverse fibres near the left margin, while several early 

 areas appear in the pyramidal and other fibres, and the grey matter in this region. 



At a higher level (fig. 123) the areas round the Vth root zones increase rapidly in size, 

 especially on the right side. The area around the aqueduct extends forwards to involve the 

 IVth nucleus and the motor fibres of the Vth nerve on each side. 



Mid-Brain (fig. 124). — A dense triangular area is found around the aqueduct of Sylvius : 

 this extends along the median raphe to the anterior surface. Two areas are found in the 

 corpora quadrigemina on one side and several small ones in the formatio reticularis on the 

 other. Sclerosis also occurs, on both sides, near the point of emergence of the Illrd nerves, 

 the fibres of which are involved. Several small areas are present in both substantia nigra, 

 one of which extends into the red nucleus on one side and another into the middle third 

 of the crus on the same side. 



Optic Tract and Chiasma. — On each side patches are found at the junction of optic tract 

 and chiasma. The remainder of both optic tracts is unaffected till near the point of its 

 passage into the corpora geniculata interna, when both are again sclerosed. The optic nerves 

 on both sides show an advanced sclerosis : this sclerosis extends on both sides up to the 

 junction of the nerve with the chiasma, and on one side extends into it. The chiasma is 

 thus less affected than optic nerves or optic tracts. 



Cerebral Hemispheres. — (1) Horizontal sections at level of the middle of the basal ganglia 

 (figs. 114-115). 



Ventricles. — Narrow bands of sclerosis are found irregularly distributed around the 

 posterior horns. On the left side one of these passes for a considerable distance into the 

 adjoining white matter and cuts across the optic radiations ; the tips of both anterior horns 

 also show similar areas, extending diffusely into the surrounding white matter ; the lateral 

 surfaces of both optic thalami are also extensively affected — the areas extending, for a varying 

 distance, into their substance. Numerous small areas are found in the substance of the 

 genu of the corpus callosum : some of these have their long axis parallel to the direction 

 of the fibres. More extensive areas are found in the splenium, and the ventricular margin 

 of the forceps major is markedly affected. The fibres of the anterior pillars of the forceps 

 also show early involvement. 



Basal Ganglia. — On the left side a well-marked oval area is present in the anterior part 

 of the substance of the thalamus : a small circular patch in the putamen of the lenticular 

 nucleus ; and three irregular areas in the white and grey matter of the island of Red, involving 

 to a slight extent the claustrum. On the right side two areas are present in the substance 



