Chapter 15 

 Order 3 Polymastigina Blochmann 



THE Zoomastigina placed in this group possess 3-8 (in one 

 family up to a dozen or more) flagella and generally speaking, 

 are minute forms with varied characters and structures. Many 

 possess a cytostome and one to many nuclei and the body is covered 

 by a thin pellicle which allows the organism to change form, although 

 each species shows a typical form. The cytoplasm does not show any 

 special cortical differentiation; in many, there is an axial structure 

 known as axostyle or axostylar filaments (p. 61). In Trichomonadi- 

 dae, there is usually a rod-like structure, known as costa (Kunstler), 

 along the base of the undulating membrane and in Devescovinidae, 

 there is a subtriangular body, the cresta, directly below the basal 

 portion of the trailing flagellum, which in some species is very large 

 and capable of movement. At the time of division, the old costa is 

 retained and a new one is formed; the cresta however is resorbed 

 and two new ones are produced (Kirby). Parabasal bodies of various 

 form and structure occur in many species. 



The majority of Polymastigina inhabit the digestive tract of ani- 

 mals and nutrition is ho lo zoic or sap ro zoic (parasitic) . Many xylopha- 

 gous forms hold symbiotic relationship with the host termites. 

 Asexual reproduction is by longitudinal fission, sometimes multiple. 

 Encystment is common, and the cyst is responsible for infection of 

 new hosts through mouth. Sexual reproduction has not been defi- 

 nitely established. 



With 1 nucleus Suborder 1 Monomonadina 



With 2 nuclei Suborder 2 Diplomonadina (p. 311) 



With more than 2 nuclei Suborder 3 Polymonadina (p. 315) 



Suborder I Monomonadina 



Without axial organella 



With 3 flagella Family 1 Trimastigidae (p. 294) 



With 4 flagella 



None undulates on body surface 



Without cell-organ of attachment. . Family 2 Tetramitidae (p. 296) 



With rostellum Family 3 Streblomastigidae (p. 298) 



One undulates on body surface . . Family 4 Chilomastigidae (p. 298) 



With more than 4 flagella Family 5 Callimastigidae (p. 299) 



With axial organella 



Without undulating membrane 

 Without cresta 



Flagella not adhering to body 



Without rostellum Family 6 Polymastigidae (p. 299) 



293 



