THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 665 



The frequent sharp delimitation of the primary isolated areas gives the impression 

 that the spread of the process is in the nature of the diffusion of a toxic substance 

 which spreads from a central focus till it exhausts itself. Williamson puts forward 

 a very suggestive view of the causation of this characteristic. The margin or outline 

 of an area is noted as passing through the structure of the brain or cord substance 

 regardless of fibre tracts, nerve cells, or vessels. He suggests that this is due to the 

 infiltration of the nerve tissue with a fluid of destructive character, the shape and 

 margins of the area being determined by physical conditions, since patches of 

 similar form can be produced when stained fluid is allowed to infiltrate the cord 

 (post-mortem) from various points. 



2. Further Advance of the Process. 

 The ebb and flow of the symptoms are, clinically, amongst the most character- 

 istic features of the disease, and, anatomically, " early " areas are the expression 

 of this recurrence of a long-standing disease. When the primary direct effect 

 of the causal agent has become exhausted the areas become sclerosed, and in 

 such cases there may be a true remission, but frequently in addition to " early " 

 areas there are found at the periphery of the old areas indications of an advanc- 

 ing process. This may be due to the persistence of the action of the primary 

 agent, or to the fact that the products of degeneration had caused a secondary 

 reaction after the infective or toxic agent had ceased to work, or, possibly, to a new 

 process surrounding the older one. Such recent areas show that the morbid agent 

 persists in the organism. Muller has urged that the similarity of the basal features 

 of the clinical and anatomical pictures points to one common cause of the disease : he 

 thinks that we cannot assume that, for example, the toxi-infective agents of the acute 

 infectious diseases, i.e. of so different a nature, will always lead to one and the same 

 definitely characteristic disease-picture. A similar view has been upheld by numerous 

 writers, and, in the absence of any specific organismal or toxic cause, an explanation 

 has been sought for along very varied lines. Redlich thinks it possible that the 

 characteristic symptom-complex is caused by the " general functional injury " to the 

 nervous system : that the acute infectious disease, whose cause we otherwise look 

 upon as specific, may yet produce a definite metabolic disturbance, which, in its 

 action upon the central nervous system, is specific. Marburg also looks upon 

 disseminated sclerosis as a " meta-infectious " disease in this sense. Such a term 

 seems justifiable in view of the use of the term meta- or para-syphilis in which it 

 was believed -that the syphilitic virus induced in the body profound metabolic 

 changes. Mott has pointed out that these resulted in a large amount of lipoids 

 occurring in the serum and in the cerebro-spinal fluid : that these same lipoids are 

 found in the normal body fluids, so that the specific character is thus manifested by 

 quantity rather than by quality. The relations of syphilis to the para-syphilitic 

 affections are of special interest in relation to the possibility that a latent organism 



