THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 649 



content — meet with a resistant factor in the numerous ganglion cells and axis 

 cylinders, so that there results a sclerosis so limited that numerous authors state 

 that it does not exist in the cortex. 



Cajal and Marinesco, in relation to the satellite cells of the grey matter, have 

 also developed Weigert's conception. It is maintained that the nerve cells and the 

 glia cells develop parallel to one another, and that in the normal state there is 

 established a nutritive equilibrium between these two elements. This equilibrium 

 probably is maintained by the secretion of certain substances — elaborated by the 

 nerve cell — which hinders the excessive development of the glia cells. The nerve 

 cells and satellite cells, therefore, constitute a kind of symbiosis, but Mott thinks 

 that the proliferation of satellite cells seen in acute toxic conditions is due to a 

 failure of assimilative metabolic processes in the nerve cells as a result of the poison. 

 There is, therefore, more nutriment at the disposal of the satellite cells, and they 

 are thereby stimulated to proliferation. 



In the description of areas in the grey matter, it has been shown that the 

 involved ganglion cells in the cortex were frequently surrounded by proliferating 

 satellite cells of various forms with numerous fine black granules in their protoplasm 

 and branching processes (osmic acid), and at other times almost replaced by nests 

 of proliferated satellite cells. In the grey matter of the spinal cord, on the other 

 hand, no such satellite cells were ever found, and the ganglion cells seem there to 

 undergo simply a gradual atrophy. 



3. Blood-vessels and Lymphatics. 



The general agreement of the areas, especially of isolated cerebral areas, with the 

 topographical distribution of the blood-vessels has long led to the belief that these 

 were primarily affected in the diseased process. The changes in the vessels may be 

 expressed, however, in very various ways : a chronic inflammation of the walls of 

 the vessel may affect the nutrition of the area supplied by it : primary thrombosis 

 or thrombosis secondary to irritation of the intimal lining, by toxins circulating in 

 the blood, might lead to similar malnutrition : some effect, toxic or mechanical, on 

 the intimal lining may lead to minute capillary haemorrhages : a primary acute 

 vascular change with peri-vascular cell infiltration — a true inflammation in the 

 generally accepted sense of the term — might extend to involve the adjoining- 

 tissue : or, finally, the vessel wall changes might lead to adhesion and closure 

 of the lymphatic sheaths with a subsequent lymph stasis in the tissues. Each 

 of these views has its adherents, and it is necessary briefly to indicate the sequence 

 of the changes. 



Rindfleisch thought that the chronic changes in the vessel walls (the cause of 

 which appeared to him quite unknown) was followed by an atrophy of the nerve 

 elements from malnutrition and a secondary glia proliferation. It is evident that 

 the areas in which such chronic vessel changes were found must have been old 



