150 SOCIÉTÉ DE BIOLOGIE 



The essential Features of the Lésions caused 

 BY Trypanosoma hippicum. 



Note de S. T. Darling, présentée par Auguste Pettit. 



Laveran, Baldwin, Mott, Thomas, Breinl,^ Claude and Renaud, Roudsky, 

 and others, hâve contributed to our knowledge of the lésions elicited by 

 pathogenic trypanosomes; and Pettit has recently niade an important contri- 

 bution to the subject by a systematic study of the lésions caused by eight 

 species of trypanosomes in as many varieties of animais. My observations 

 with Tr. hip2oicurn tend io confirm and amplifyhis fmdings and interprétations. 



I hâve studied lésions in mules and horses, monkeys {Cebus and Nyctipi- 

 thecus), coati {Nasua narica), raccoon, dog, rabbit, guinea pig, rat and 

 mouse ; and with the exception of Nyctipithecus a.nd the raccoon comparisons 

 hâve been made with normal tissues. 



The lésions, similar in type to those caused by other pathogenic 

 trypanosomes, are due to an intoxication resulting in cellular degene- 

 raTions, anémia, lymphocytosis, terminal ecchymoses of serous and 

 mucous membranes, œdema and extensive hyperplasia of lymphoid 

 and myeloid tissu e, with focal, cellular infiltrations which are partly 

 inflammatory and partly haemopoietic in function. 



Spleen : Great enlargement was more common in the smaller animais, 

 in which there was a higher degree of infection, and consequently a 

 greater need for mononuclear phagocytes. 



The enlargement was due to a greatly increased number of retained 

 erythrocytes in various stages of décline, phagocyted and free hemosiderin, 

 large phagocytes, and to hyperplasia of the Malpighian corpuscles, as well 

 as lo large and small lymphocytes in the splenic spaces. In the coati, guinea pig 

 rat and mouse, there was an augmentât on of tl number of megakaryocytes 

 and nucleated red cells, normally found in thèse animais. There were also 

 foci of eosinopliilic leucocytes in the coati. The périphéries of the malpi- 

 ghian corpuscles of a mule showed a transition into plastic cells resembling 

 the polyblasts of Maxiraow. Cells identical with thèse vere also found throug- 

 hout the blood stream and in areas of necrosis and cellular infiltration. 



Bone Marrow : The yellow marrow became transformed into cellular 

 red marrow containing many megakaryocytes. 



Liver : The sinusoids usually contained a great excess of leucocytes 

 in which mononuclear cells frequently predominated. Thèse, with 

 nécroses, were very constant in mules. Nécroses were common in ail 

 animais, and were of Iwo types, each one suggesting a distinct etiolo- 

 gical agent. In the central zones the nécroses were hyaline or fatty 

 and of large size, and relatively free from leucocytic infiltration. Those 

 in the intermediate and peripheral zone were smaller and the hepatic 

 cells were replaced by polymorphonuclear and mononuclear leuco- 



