THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 703 



of the thalamus, in addition to the irregular zone of sclerosis extending inwards from the 

 ventricular surface. 



Convolutions. — Left side. Numerous very minute areas are found in the white matter 

 of the frontal, parietal, and occipital lobes. An oval area is present at the foot of the fissure 

 of Rolando in the medullary ray, and several small areas are confined to the parietal grey 

 matter. A long narrow patch is present in the white matter of the occipital lobe : this 

 involves the tapetal fibres, the inferior longitudinal fasciculus, and the optic radiations, 

 and projects into the grey matter of the calcarine fissure. On the right side also several 

 small areas are found in the white substance of each lobe : a very defined area is present 

 at the foot of the fissure of Rolando — in a position almost exactly corresponding to the 

 area on the left side — and the optic radiation is here again extensively involved. 



(2) Horizontal sections immediately above the roof of the lateral ventricles (fig. 117). On 

 the left side seven isolated areas, in various stages of development, are present in the white 

 matter : these cut across the superior longitudinal fasciculus and the corona radiata. Several 

 of these areas are surrounded by a zone of lighter staining. On the mesial surface the grey 

 matter, especially on the surface of the convolutions, is very definitely involved. On the 

 left side the cups of several of the convolutions on the mesial surface of the frontal lobe 

 are picked out by a well-marked sclerosis ; other areas are found in the white matter of 

 the frontal lobe, and one very well-defined patch involves both medullary ray and grey matter 

 of the convolution atf the tip of the lobe. Another well-defined area, involving both grey 

 and white matter, is present at the foot of the fissure of Rolando, in its anterior wall, and a 

 smaller patch in the white matter of the post-Rolandic convolution, together with two 

 early areas in the white matter at the foot of this gyrus. The cups of two of the convolu- 

 tions in the parieto-occipital fissure are also affected. 



(3) Sections of the hemispheres 1 cm. above the roof of the ventricles. Here only 

 two areas could be detected microscopically : one in a convolution of the internal parieto- 

 occipital fissure : this was an elongated oval patch which involved the medullary ray 

 and extended into the adjoining grey matter on one side ; the other area is found on the 

 mesial surface of the marginal convolution. 



(4) Sections at a still higher level (fig. 116) also show few areas. One is found in the 

 white matter of the post-Rolandic gyrus, and one in the white matter of the upper frontal 

 convolution towards the mesial surface. 



(5) Sections through the hemispheres at their highest level. These show a sudden 

 increase in the number of the areas. On the left side at least twelve can be identified micro- 

 scopically. A very large oval patch is present at the foot of the Rolandic fissure : this 

 extends across the grey matter into the white matter and then into the grey matter of the 

 marginal convolution. Another oval area, involving both grey and white matter, is present 

 on the mesial surface of the frontal lobe, and on the outer surface of this lobe three areas 

 are present ; one in the grey matter alone, one involving both grey and white matter, and 

 the third in the medullary ray alone. Behind the pre-central fissure two areas are present : 

 one limited to the grey matter and one to the medullary ray ; and at the foot of the intra- 

 parietal fissure a clearly-marked area involves the cup of the convolution. Small areas 

 cocur in the posterior part of the section. 



(6) Sagittal sections through the temporo-sphenoidal lobe. These show a well- 

 marked peri-ventricular sclerosis around the descending horn of the lateral ventricle. This 

 extends into the adjoining white matter, intersecting the inferior longitudinal fasciculus 

 and spreading into the radiations. The white matter of the hippocampal convolution is 

 also extensively affected. 



