674 DR JAMES W. DAWSON ON 



(2) that acutely-inflamed areas are rarely present, and (3) that in subacute 

 processes the general architecture of the tissue is retained, it is concluded that : 

 (i) The process underlying disseminated sclerosis is a subacute disseminated 

 encephalo-myelitis, which terminates in disseminated areas of actual and complete 

 sclerosis. 



It has been contended, however, by Schmatjs, Ziegler, Strumpell, and Muller 

 that there are two forms of disseminated sclerosis : the one, true primary dis- 

 seminated sclerosis, which develops on the basis of an increasing glia hyperplasia 

 — with developmental factors as its determining cause ; the other, secondary 

 disseminated sclerosis, which develops on the basis of an inflammatory process ; 

 and further, that the two forms can be clinically and anatomically distinguished 

 from each other. This point of view is admirably simple, and I admit not only 

 that certain areas in individual cases arise on the basis of an increasing glia 

 hyperplasia — for such in small numbers are present in my cases — but also that, 

 in certain cases of disseminated sclerosis in which the symptoms evolve very 

 gradually, the areas might altogether develop on such a basis — discounting, however, 

 the developmental factor. But when Muller, who is the most strenuous upholder 

 of this position, further contends that disseminated sclerosis, developing on such a 

 basis, is a " comparatively common disease" in contrast to secondary disseminated 

 sclerosis, and further states that the essential histological characteristic of the areas 

 in the latter forms is " areolar," it is at once obvious that this study prevents the 

 acceptance of such a uniform conception of the process — a conception which would 

 rule out each of the nine cases. Muller defends his position by arguments based 

 on clinical and anatomical data, and the objections to his contentions may be put 

 from these two points of view — clinical and anatomical. The question whether this 

 is a position compatible with clinical experience lies outside the scope of this paper, 

 and can be only briefly alluded to. My position is, naturally, determined by the 

 cases that have come under histological observation. In these, two things stand out 

 clearly : the one that the clinical notes, though admittedly meagre, point to a sub- 

 acute onset of the symptoms, with no apparent immediate cause (see later), to 

 periods of quiescence and betterment followed by relapses, again with subacute 

 onset, and to the circumstance that these symptoms are quite compatible with the 

 variability of the symptoms found in disseminated sclerosis. The second and more 

 decisive fact, however, is related to the character of the areas. On pages 638-644 have 

 been given Muller's criteria of the anatomical characteristics of the areas of primary 

 and secondary sclerosis : it has also been stated above that the great majority of the 

 areas in these cases develop on the basis of an inflammatory process, in Muller's 

 sense, and that in the end-result they bear all the characteristics ascribed by Muller 

 to areas in primary disseminated sclerosis, i.e. with dense glia meshes in which 

 persistent axis cylinders may frequently be found, and altogether different from the 



