THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 523 



in the same case ; some patches presenting firm sclerosis, whilst others are soft and 

 recent, and may resemble ordinary softening." 



A brief reference must now be made to some of the main problems met with in 

 the study of the pathology and pathogenesis of disseminated sclerosis. Recent 

 works show how widely views differ regarding these, and how vague and confused 

 are the issues placed before the reader. One reason for this seems to lie in the 

 absence of any distinction being drawn between the question of the nature and that 

 of the origin of the process. These are undoubtedly the two most important 

 problems : (l) what is the nature of the process underlying disseminated sclerosis? 

 and (2) where has it its origin, i.e. in which structural element of the nervous tissue 

 does it take its rise ? 



An attempt to answer the first of these questions has led many writers to 

 a diffuse discussion regarding the distinction between inflammatory and non- 

 inflammatory processes in the central nervous system. The views as to what 

 constitutes true inflammation are nowhere so conflicting as when the term is used 

 in connection with the central nervous system, and in the case of no other organ 

 are the conceptions of different writers as to the relation of inflammation to pure 

 degeneration so fundamentally opposed. The nature of chronic inflammation also is 

 again nowhere so obscure as when the term is used in connection with the central 

 nervous system. Schmaus (1903) has summarised the inflammatory process in the 

 central nervous system under the general conception of a reaction process, which 

 may express itself by an increase in the vital activity of any of the tissue elements, 

 and, for the purposes of this paper, the term is used in this sense 



The pathological anatomy of disseminated sclerosis bears no analogy to any 

 other known pathological process in the body. We know, e.g., of no process in 

 other organs in which the relative integrity of the specific functioning parenchy- 

 matous tissue is associated with the enormous increase of the interstitial tissue 

 occurring in definite circumscribed areas. 



Further, experimental investigation has as yet thrown little light on this 

 question : it has proved only that disseminated areas of myelitis may result in a 

 reparative growth of neuroglia, but it has not proved that areas of disseminated 

 sclerosis proceed from an acute myelitis. 



The attempt to define more clearly the nature of the process is rendered more 

 difficult, therefore, by the difficulty of defining the term inflammation in the central 

 nervous system, by the absence of analogies from the pathology of other organs, and 

 by the absence of results realised from experimental investigations. 



Two views in particular have been advanced to explain the nature of the process. 

 Byrom Bramwell (1904) has succinctly summarised them thus: " (l) That the 

 sclerotic lesions are the result of some irritant which is distributed through the 

 nerve centres by the blood-vessels. (2) That the disease is due to some develop- 



