THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 677 



be wanting. The grounds for such a view are based largely upon an increasing 

 knowledge of the selective character of toxins. Several instances of such have been 

 given in an earlier section, and here allusion may be made to progressive lenticular 

 degeneration — -a symmetrical degeneration of the lenticular nuclei — which Wilson 

 traces to the selective action of the morbid agent on these collections of grey matter ; 

 and also to the secondary neuroses (psychoses) following the various fevers, e.g. 

 pneumonia and typhoid fever, which Kraepelin has differentiated from one another. 

 Analogies can never be conclusive, but they at least mark the possible direction in 

 which we may look for a solution and allow of the suggestion that a characteristic 

 anatomical and clinical picture is called forth by a specific morbid agent. 



It is probable, however, that the significance of acute infectious diseases, when 

 they occur in the anamnesis in definite time relationship to the onset of symptoms, 

 is that which has been attributed also to chill, trauma, psychical shock, and all the 

 recognised external factors : that they are capable of acting only as exciting- factors 

 manifesting or aggravating the condition. In four of the nine cases from which the 

 material of this study has been drawn the symptoms came on without apparent cause, 

 and in the other cases the chill, trauma, shock, influenza, and miscarriage cannot be 

 regarded as in immediate causal relationship. The duration of the series of cases is 

 as follows : fifteen months, four years, five years, in three cases ten years, fifteen 

 years, and seventeen years. Eight of the nine patients were young women, whose 

 ages averaged slightly over twenty years at the time of the first appearance of 

 the symptoms. 



The essential points of difference between the standpoint of Ziegler, Strumpell, 

 and Muller and my own are very few, but they are basal. These writers confine 

 true disseminated sclerosis to a disease with a characteristic clinical course, i.e. with 

 remissions and relapses. So far we agree, but this condition has, as its anatomical 

 expression, an increasing glia hyperplasia (for the present the developmental factor 

 at its basis may be left out of account), and from this pathological conception all the 

 nine cases must be excluded. Further, these writers look upon secondary disseminated 

 sclerosis as chiefly due to toxi-infective agents, and these forms have as their 

 anatomical expression " areolierte " areas, and again, from this pathological conception 

 all the nine cases are ruled out. It may be argued that the notes in some of the 

 cases do not justify our looking upon them as cases of true disseminated sclerosis, 

 but if these are omitted and those only included which sufficiently point to their 

 inclusion in Muller's clinical picture of true disseminated sclerosis, there still 

 remains overwhelming evidence that the great majority of the areas arise on the 

 basis of an inflammatory process, and lead to areas of actual sclerosis in Muller's 

 sense. In five out of the nine cases areas in all stages of development were found 

 in both brain and cord ; in three, the areas in the cord were mostly of an older 

 date, and those in the brain at all stages ; while in one case the spinal cord areas 

 were all of an early type, and those in the brain of a more sclerotic type. It is, 



TRANS. ROY. SOO. EDIN., VOL. L, PART III (NO. 18). 94 



