THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 533 



point to the primary dependence on the blood-vessels. Williamson records a case 

 where one of the areas corresponded roughly with the distribution of the anterior 

 median artery of the spinal cord at one region, and the vessels in the anterior median 

 fissure were dilated and surrounded by round cells and nuclei before they entered 

 the substance of the cord. A thrombus was also present in the anterior median vein 

 just at the commencement of the anterior median fissure, and several small throm- 

 bosed veins were found in the pia mater on the surface of the cord. 



The pathological changes in disseminated sclerosis are thought to be very 

 suggestive of the presence of some irritating substance in the blood, which stimulates 

 the endothelium of the walls of blood-vessels and of the walls of the peri-vascular 

 lymphatics, and which causes an extravasation of toxic lymph into the surrounding 

 nerve tissue, with consequent degeneration of the myelin sheath of the nerve fibre. 

 The presence of recent patches alongside old patches shows that the morbid agent 

 persists in the organism and is able to cause the development of new patches of the 

 disease long after the onset of the affection. 



Goldscheider (1896). The views of this writer are very similar to those of 

 Williamson. He believes that the walls of the blood-vessels play an important role 

 in the process, and that substances giving rise to cell-proliferation affect the walls of 

 the blood-vessels by filtration and diffusion from the blood. The peri-vascular 

 inflammation leads first to a solution of the surrounding myelin, and this leads to a 

 reactive interstitial inflammation. Goldscheider thinks that disseminated sclerosis 

 is a disseminated myelitis running in acute and subacute stages. 



D. Disturbances in the Lymph Circulation. 



Changes in the lymphatics of the central nervous system have recently received 

 considerable attention. In disseminated sclerosis the lymphatic spaces of the 

 adventitia of the blood-vessels are frequently distended and filled either with fluid 

 or with cells, or they are more or less obliterated by dense fibrous tissue. Borst was 

 the first to bring these changes, which are dependent on a primary disease of the 

 blood-vessels, into causal relationship to the areas of sclerosis. The disturbed lymph 

 circulation expresses itself in characteristic serous infiltration, and the obstruction to 

 the return of the lymph causes a lymph stasis in the area, which leads both to a 

 myelin sheath degeneration and a forcing apart of the meshes of the glia, on the 

 basis of a hyperlymphosis. 



Borst (1897-1904) made a very careful histological investigation in five cases of 

 disseminated sclerosis. He has also written a review of the whole subject (1904), a 

 review to which I have already expressed my frequent indebtedness. On the 

 grounds of his own investigations Borst thinks that the indications of lymph con- 

 gestion and lymph stasis were sufficiently significant to account for the origin and 

 for the dissemination of the areas. The areas were very sharply denned macroscopic- 

 TRANS. ROY. SOC. EDIN., VOL. L, PART III (NO. 18). 76 



