THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 563 



isolated in the white matter varied in diameter from 1 to 10 or 12 millimetres, 

 and were mostly oval or circular. The largest were found in the immediate 

 neighbourhood of the roof of the lateral ventricle, and gave the impression of 

 being upward extensions of the peri-ventricular sclerosis of the roof. 



In examining the microscopic findings it is important to recognise that different 

 stages of the disease come under observation, and it would appear natural to differ- 

 entiate acute, subacute, and chronic stages, for they are often enough found close 

 together in one and the same case. The finding at the autopsy of patches at 

 different stages in their evolution accords with the clinical history of the affection, 

 which has usually progressed with remissions and relapses. It is, however, by no 

 means universally admitted that the recent areas are transformed into those which 

 would seem to represent a chronic process, in which all traces of inflammation have 

 disappeared. If such chronic areas do not develop on the basis of the former, it 

 must be acknowledged that there is a strong justification for looking upon them 

 as a multiple gliosis, related to an anomaly of development, and upon the recent 

 areas as an acquired form of sclerosis, whose origin lies probably in toxi-infective 

 conditions. 



This study, therefore, begins with a short description of these two types of 

 areas; the one an old area, typical of the "sclerose en plaques "of the earlier 

 writers ; the other, a recent area, corresponding to those found in the so-called acute 

 multiple sclerosis of recent writers. It will then be necessary to endeavour to 

 trace all the stages in the development of an actual sclerotic area, and further to 

 describe other types of areas present. A second section will deal with the 

 structure of areas in special situations, e.g. peri-ventricular sclerosis, cortical and 

 combined subcortical and cortical areas, areas in the grey matter of the cord, areas 

 in the cerebellum, nerve roots, etc. A further section will deal with the changes 

 in the individual structural components of the central nervous system, and a final 

 section with other features, e.g. the form, symmetry, and distribution of the areas, 

 and changes such as secondary degeneration outside of the area. 



(2) Structure of Different Types of Areas, 



1. An Actual Sclerotic Area. 



(a) In the Spinal Cord. 



(i) Nerve fibres cut longitudinally (figs. 4, 31, 331-336, and 341, 342), e.g. 

 in the ventral third of the posterior columns. 



The histological structure of such an area is a very simple one. It consists 

 almost entirely of newly-formed fibrils which are arranged parallel to the original 

 course of the nerve fibres. In sections stained by means of Weigert's medullated 



