Chapter 3 



THE 

 HBmHAGEUATBS 



The flagellates belong to the class 

 Mastigasida. They have 1 or more fla- 

 gella, and a few have pseudopods as well. 

 Their nutrition is holophytic, holozoic or 

 saprozoic. They multiply by longitudinal 

 binary fission, and many produce cysts. 



The class is divided into 2 subclasses, 

 Phytomastigasina and Zoomastigasina. 

 The former contains the phytoflagellates, 

 the great majority of which are free-living 

 and holophytic. Those of parasitic interest 

 will be discussed in Chapter 6. 



It is convenient for our purposes to 

 divide the Zoomastigasina into 2 groups, 

 the hemoflagellates which live in the blood, 

 lymph and tissues, and the other flagel- 

 lates which live in the intestine and other 

 body cavities. 



FAMILY TRYPANOSOMATIDAE 



The hemoflagellates all belong to the 

 family Trypanosomatidae. Members of 

 this family have a leaf-like or sometimes 

 a rounded body containing one nucleus. 

 They have a single flagellum which arises 

 from a basal granule or blepharoplast 

 posterior to the end of an elongate blind 

 pouch or reservoir and passes anteriorly, 

 usually extending beyond the body. A con- 

 tractile vacuole opens into the reservoir, 

 but both of these structures can be seen 

 only with the phase microscope and not 

 with the ordinary light microscope (Ket- 

 terer, 1952; Cosgrove and Kessel, 1958; 

 Clark, 1959). The flagellar axonenie is 

 composed of 9 peripheral and 2 central 

 fibrils (Anderson, Saxe and Beams, 1956). 

 An undulating membrane is present in 

 some genera; the flagellum lies in its outer 

 border. Posterior to the basal granule is 

 a rod-shaped or spherical kinetoplast con- 

 taining deoxyribonucleic acid. The struc- 

 ture of the kinetoplast as seen in electron 

 micrographs has been interpreted in dif- 

 ferent ways. According to Anderson, Saxe 

 and Beams (1956), it consists of lamellae 

 oriented at right angles to its long axis; 



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