520 DR JAMES W. DAWSON ON 



The earliest pathological studies in disseminated sclerosis were made in chronic 

 cases of the disease, and the lesions described were the sclerotic areas found distri- 

 buted in the brain and spinal cord. The recognition by later writers of acute stages 

 of the disease and of cases of typical disseminated sclerosis running an acute course 

 has caused me to direct special attention to the early changes and their relation to 

 the development of the chronic sclerotic areas. In spite of the large number of 

 works on the subject of disseminated sclerosis, its etiology and pathology present 

 many problems for future elucidation. Our knowledge of the histology, especially 

 of the early stages, has not kept pace with our recognition of the early clinical 

 aspects of the disease. It was hoped, therefore, that a study of the earliest lesions, 

 in tracing the role which falls to the various tissue elements before secondary 

 factors had been introduced, would throw some light upon the nature and origin 

 of the process. 



No attempt has been made to give a complete representation of the literature of 

 the subject. This is so extensive that it would scarcely have been possible, and, 

 further, a detailed statement of all the hypotheses, often very vague and 

 insufficiently based, seemed of little value. I have had in view, rather, a brief 

 continuous account of the most important problems met with in the considera- 

 tion of the pathological anatomy and pathogenesis of disseminated sclerosis. 

 Having critically sifted all the available literature of the last twenty years, 

 those writers have been chosen whose work has marked a new standpoint 

 or an important step in our progressive knowledge of the subject. . In the 

 critical discussion on the nature, origin, and cause of disseminated sclerosis, the 

 works of Borst (1904) and M tiller (1904) have been freely drawn upon, and readers 

 are referred to Muller's monograph for a complete bibliography up to 1904. 

 A list of the more recent anatomical researches will be found at the close of 

 this study. 



The clinical notes of the cases were very incomplete, and no attempt has been 

 made to correlate clinical symptoms with the anatomical lesions in individual cases. 

 The difficulty of bringing clinical symptoms into harmony with the anatomical 

 findings in the central nervous system is a well-recognised fact, but, from the frequency 

 with which certain areas are affected, attention has been drawn in the note on 

 the Pathological Physiology to the possibility of predominant anatomical lesions 

 explaining certain clinical symptoms. 



As the significance and interpretation of our observations depend largely upon 

 the judgment we pass upon, and the importance we attach to, the methods of 

 investigation used, I have given in considerable detail an outline of the methods 

 employed. During the last third of the nineteenth century neuro-pathology laid 

 special stress on problems affecting the localisation of nerve fibres in an endeavour 

 to define accurately the position of diseased processes, and to follow out secondary 

 degenerations while almost neglecting the histo-pathology of the diseased processes 



