THE AFRICAN TRYPANOSOMIASES 



ing a clear eosinophile area; (d) a few mononuclear leucocytes; 

 (e) a few polymorphonuclear leucocytes. The cells of Marschalko 

 are considered by Mott to be derived from lymphocytes, and the 

 morula cells to be degenerated cells of Marschalko. Mott considers 

 that the lymphocytes are probably formed by proliferation of the 

 endothelial cells of the perivascular lymphatic space. According 

 to Breinl, a layer of blood cells may be found external to the round 

 cells, and haemorrhages may be found in the cord. The ependyma of 

 the lateral ventricle also shows a proliferation and dense fibrous 

 formation at times. With regard to the parenchymatous elements, 

 Mott considers that there may be increase in neuroglial nuclei and 

 lymphocytes in the perineural spaces, while there is atrophy of the 

 dendrons and diminution of the Nissl bodies, and alteration in the 

 nucleus, which becomes large, clear, and excentric. These changes 

 are most marked in the cerebral cortex and medulla, and less so in the 

 spinal cord. The cells of the posterior spinal ganglion, however, show 

 chromatolysis. The central canal of the spinal cord may be dilated, 

 but is more generally occluded by proliferation of the cells of the 

 ependyma. It is interesting to note that Mott did not find any of 

 these changes in the brain and spinal cord of a cured case of try- 

 panosomiasis, who died several years later of cystic disease. 



The histological lesions of the encephalitis found in sleeping sickness closely 

 resemble those of general paralysis and encephalitis lethargica (nona). 



The next series of characteristic changes are in the lymphatic 

 glands, in which trypanosomes are often found. These changes 

 begin with a conversion of the lymphocytes into cells of Marschalko, 

 and these, again, into morula cells. The endothelial cells of the 

 lymph sinus proliferate and take on a phagocytic action, containing 

 lymphocytes, red blood cells, and chromatin particles. At the same 

 time the gland becomes intensely congested, and the fibrous tissue 

 of the capsule and septa proliferates, so that they and the walls of 

 the lymph sinuses and of the vessels become thickened. 



A lymph nodule therefore appears to be surrounded by a fine 

 connective meshwork, containing few lymphocytes, but many red 

 corpuscles and phagocytes. As time goes on, the inflammation in 

 the gland subsides, and it becomes less vascular, firm, and hard, and 

 full of dense fibrous tissue. Secondary infection, however, may 

 occur with the formation of abscesses. 



Microscopically, the lungs may be found to be hypersemic, even 

 when normal, to the naked eye, while the complication of pneu- 

 monia will give rise to the usual appearances. The heart shows 

 small-celled infiltration in all its layers, with sometimes haemor- 

 rhages. Vianna has noted in animals infected with C. castellanii 

 cysts in the muscles similar to those of S. cruzi, and appears to have 

 found them also in the muscular and nervous tissues from a case of 

 sleeping sickness. The liver and spleen may show thickening of the 

 capsule, while the latter is very congested, and its trabeculae are in- 

 creased in thickness. In natives signs of chronic malaria are almost 



