CHAPTHR XI. 



DISEASES CAUSED BY PROTOZOA 

 GENUS TRYPANOSOMA. 



§304. Classification of Trypanosoma. The Trypan- 

 osoma belong to the protozoa, but their species diagnosis is 

 not satisfactoril}' determined. A number of classifications of 

 these organisms have been proposed. The one suggested by 

 Salmon and Stiles is appended. 



Protozoa, class Masfigophora, subclass Flagellata, order 

 Monadida, family Trypanosomidae, genus Trypanosoma Gruby. 



According to Stiles the family contains at present two 

 genera, which are distinguished as follows : 



1. One flagellum present, extending from the centrosome along 



the undulatingmembrane and becoming free at the anterior 

 extremity Trypanosoma 



2. Two flagella, one extending anteriorly, the other pos- 



teriorly Trypano plasma 



Generic diagnosis of Trypanosoma. " Body fusiform, presenting a 

 lateral, longitudinal, undulating membrane, the thickened border of 

 which terminates posteriorly, in the posterior half of the body in a 

 ' centrosome,' and is prolonged anteriorh^ in a free major flagellum ; 

 nucleus generally anterior ; there is a tendency to agglomeration by 

 the posterior extremity ; divisions longitudinal and unequal. Parasitic 

 in the blood of vertebrates." 



In order that a somewhat definite idea of the structure of 

 these organisms may be obtained the specific characters of Tr. 

 Lewisi are quoted. 



Trypanosoma : "8 to 10 // long, 2 to 3 // broad, 24 to 34 a long by 

 1.44 broad (Laveran and Mesnil, 1901) ; a very refringent granule (near 

 centrosome ) in place of which a clear vacuole is seen in stained prepara- 

 tions. Animalcules exceedingly minute, alternate and vermicular 

 under normal conditions, but highly polymorphic and capable of assum- 

 ing a variety of contours ; flagellum single, terminal, two or three times 

 the length of the extended body. No contraclible vesicle ... as 

 yet detected. Habitat, blood of the rat and hamster. " 



