CHAPTER XI. 



DISEASES CAUSED BY PROTOZOA 

 GENUS TRYPANOSOMA. 



§304. Classification of Trypanosoma. The Trypan- 

 osoma belong to the protozoa, but their species diagnosis is 

 not satisfactorily determined. A number of classifications of 

 these organisms have been proposed. The one suggested by 

 Salmon and Stiles is appended. 



Protozoa, clads Mastigophora , 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 undulating membrane and becoming free at the anterior 

 extremity Trypanosotna 



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



teriorly Trypanoplastna 



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 anteriorly 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 u long, 2 to 3 /( broad, 24 to 34 jx 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 contractible vesicle ... as 

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



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