THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 633 



white matter, especially towards the occipital lobe — the largest of these measuring 

 1 X f centimetre. 



In the convolutions one small area is present at the tip of the frontal lobe ; 

 another occupies completely the medullary ray of the post-Rolandic gyrus ; another 

 is at the junction of the white and grey matter of the pre-cuneus, and two others, 

 both circular in outline, occur in the grey matter of the calcarine region — one on 

 the outer and one on the mesial surface. 



The opposite surface of the cerebral hemisphere at this level shows a very similar 

 affection and distribution. 



(3) Above the ventricles (fig. 25). 



Numerous areas occur in the white and grey matter of both hemispheres. In the 

 frontal lobe on the right side one large irregular patch occupies the centre of the 

 white matter ; several smaller areas are found on either side ; and three early 

 patches extend from the white matter into the medullary rays of the convolutions at 

 the tip of the lobe. A small oval area is present in the post-Rolandic convolution at 

 the junction of white and grey matter, while a smaller one is present in the white 

 matter adjoining it. Another very well-marked area is present in the calcarine 

 fissure : this extends from fissure to fissure, undermining completely the upper 

 portion of the arcus parieto-occipitalis. Two or three small areas, confined to the 

 grey matter, are also present in this region. 



(4) Horizontal sections through the temporo-sphenoidal lobe (fig. 29). 



Sections just below the floor of the descending and posterior horns of the lateral 

 ventricle show on both sides large irregular areas of sclerosis, which represent the 

 downward continuation of the peri-ventricular sclerosis which has affected both these 

 horns. The areas extend from the white matter almost to the surface of the 

 convolutions, and the anterior margins of the descending horns are similarly affected. 

 The sclerosis involves the greater part of the course of the occipito-temporal bundle 

 of fibres ; the convolutions in the region of the calcarine fissure are extensively 

 involved — especially in the more superficial fibres of the grey matter ; similar but 

 more defined areas are present in almost all of the convolutions at the tip of the 

 temporo-sphenoidal lobes ; and the fibres of the hippocampal convolutions are also 

 markedly affected. 



3. Note on the Pathological Physiology. 



There is no disease of the nervous system in which the symptoms may be more 

 varied, in origin and in succession, than in disseminated sclerosis, a fact which can 

 be well understood when one considers the wide range and irregular distribution of 

 the areas of sclerosis. These, as we have seen, may occur in almost any part of the 

 nervous system, producing peculiar symptoms and combinations of symptoms, which 



