238 PHUTOZUOl.OC.Y 



flagellum and radiating pseudopods; ordinarily attached to for- 

 eign object with a cytoplasmic process, but swims freely by with- 

 drawing it; nucleus central; several contractile vacuoles; holo- 

 zoic. 



A. mirabilis K. (Fig. 108, h). Numerous simple filopodia; about 

 lO^i in diameter; flagellum 20yu long; fresh water. 



Genus Dimorpha Gruber. Ovoid or subspherical ; with 2 flagella 

 and radiating axopodia, all arising from an eccentric centriole ; 

 nucleus eccentric; pseudopods sometimes withdrawn; fresh water. 



D. mutans G. (Fig. 108, c). 15-20yu in diameter; flagella about 

 20-30m long. 



Genus Pteridomonas Penard. Small, heart-shaped; usually at- 

 tached with a long cytoplasmic process ; from opposite pole there 

 arises a single flagellum, around which occurs a ring of extremely 

 fine filopods; nucleus central; a contractile vacuole; holozoic; 

 fresh water. 



P. pulex P. (Fig. 108, d). 6-12^ broad. 



Genus Histomonas Tyzzer. Parasitic in domestic fowls; body 

 amoeboid with a blepharoplast; indication of flagellum (?); with- 

 out cytostome. 



H. meleagris (Smith) (Fig. 108, e). 12-21/i long; rounded re- 

 sistant phase up to ll^t by 9;u; the cause of the "blackhead" dis- 

 ease of young turkeys, chicken, grouse, and quail (Tyzzer) in 

 which the intestinal mucosa as well as liver tissues become in- 

 fected by this organism. 



Genus Rhizomastix Alexeieff. Body amoeboid; nucleus central: 

 blepharoplast located between nucleus and posterior end; a long 

 fiber (rhizostyle) runs from it to anterior end and continues into 

 the flagellum; without contractile vacuole; division in spherical 

 cyst. 



R. gracilis A. (Fig. 108, /). 8-14/i long; flagellum l^ifx long; in 

 intestine of axolotles and tipulid larvae. 



References 



Becker, E. R. 1925 The morphology of Mastigina hylae (Fren- 

 zel) from the intestine of the tadpole. Jour. Paras., Vol. 11. 



Lemmermann, E. 1914 Pantostomatinae. Siisswasser flora 

 Deutschlands, etc. H. 1. 



Tyzzer, E. E. 1919 Developmental phases of the Protozoon of 

 "blackhead" in Turkeys. Jour. Med. Res., Vol. 40. 



