34 



Morphology. 17-28 by 1*5-3^. The blepharo- 

 plast is oval. There is not uncommonly a vacuole 

 in close association with it. The trypanosome, 

 at least in animals, occurs in two main forms, a long 

 and a short. With regard to the alleged sexual forms 

 occurring in the fly vide p. 341. 



The Spleen. Is considerably enlarged and con- 

 gested. 



Brain. The pia-arachnoid shews patchy thicken- 

 ing and opacity, especially at the base. Microscopically 

 the brain shews an absolutely characteristic change, viz., 

 chronic inflammation of the perivascular lymphatics. 

 Around the vessel there is always present a neuroglia cell 

 proliferation, and the branches of these cells form a 

 reticulum. In this reticulum occur a large number 

 of lymphocytes and plasma cells of Marschalko (p. 8). 



Besides this characteristic cell there are found also 

 makrophages, which are possibly altered perivascular 

 lymphatic endothelial cells ; so-called morular or 

 granule cells, i.e., cells containing a number of spherules 

 that stain with eosin ; and degenerated trypanosomes 

 and chromatin particles, probably nuclear remains of 

 the former. 



Lymphatic Glands. Are soft and moveable, and 

 the deeper ones may be as big as a walnut. They shew 

 increased vascularity (haemolymph glands) and chronic 

 inflammatory changes resembling those in the brain, 

 viz. : 



(1) Lymphocytes in all stages up to plasma cells 

 occur. 



(2) Proliferation of the connective tissue cells of 

 the reticulum of a lymph sinus, and marked prolifera- 

 tion of the nuclei* of the endothelial cells. 



(3) When the inflammation subsides they become 

 fibrous. 



