MORBID ANATOMY 317 



vessels, as well as inflammatory lesions. On microscopic ex- 

 amination we find an increase of the plasma cells, augmenta- 

 tion of the reticular substance, fibrinous in character, between 

 the several layers of the meninges. 



2. The epithelium of the cerebro-spinal central canal has 

 proliferated. In the gray matter which surrounds the canal, 

 and especially in that of the floor, hemorrhages, sometimes 

 symmetrical, are often found. Microscopically, we often find 

 an obliteration or thrombosis of a vessel by a reticulated, hya- 

 line, pigmented material or bj' leucocytes or hyaline globules, 

 and sometimes a hyaline degeneration or even inflammation of 

 the vascular tunic. The extravasated blood also contains 

 much of the hyaline material. The hemorrhages are often 

 limited b}' the lymphatic sheath of the vessels. At the same 

 time the epithelium of the ventricles and central canal may be 

 partially lost. This last is occasionally filled with blood or 

 plugs, either granular or hyaline in character. 



3. With the naked eye small centers of degeneration 

 may sometimes be noted in the gra}^ matter, but often the}- 

 may be sought for in vain. 



4. The most constant lesions are microscopic in charac- 

 ter ; they are found more especially in tli£ gray matter sur- 

 rounding the cerebro-spinal canal and in the motor centers of 

 the medulla and spinal cord. These lesions consist at first in 

 hypersemia and accumulations of embryonic cells around the 

 small vessels, perithelial or migrator}' in origin, often showing 

 indirect division ; finally there are also found lesions of nerve 

 cells. 



5. The lesion of the nervous elements of the parts indi- 

 cated is quite characteristic ; it consists of signs of prolifera- 

 tion, namely, in the presence of several small cells in place of 

 one large one, or in a uniform degeneration and often in the 

 appearance of vacuoles with a reduction in size or disappear- 

 ance of the nucleus, or, again, its chromatic network disap- 

 pears. These cells frequenth' contain pigment. Round uni- 

 nuclear, more rarely multinuclear, elements of a lymphatic 

 origin often invade the protoplasm even of the cell and fill out 



