462 



PROTOZOOLOGY 



E. grcgariniformis (Tyzzer). In the caeca of fowls; 4-12ju in di- 

 ameter; cysts uninucleate (Tyzzer, 1920). 



E. clevelandi Gutierrez-Ballesteros and Wenrich (Fig. 196, e, /). 

 In the rectal contents of Pseudemys floridana mobilensis ; tropho- 

 zoites 5-1 -ijj, in diameter; cysts tetranucleate, 4.5-10/z large. 



E. ranarum Epstein and Ilovaisky. In the colon of frogs; cysts 

 octonucleate, up to 25/x in diameter. 



E. blattae Lucas. In the colon of cockroaches; trophozoites 3-1 5/z 

 long; cysts, 7-1 l^t in diameter and with one to three nuclei (Lucas, 

 1927). 



Genus Dientamoeba Jepps and Dobell. Small amoeba; number of 

 binucleate trophozoites often greater than that of uninucleate 

 forms; nuclear membrane delicate; endosome consists of several 

 chromatin granules embedded in plasmosomic substances and 

 connected with the membrane by delicate strands (Fig. 187, e) ; in 

 colon of man (Jepps and Dobell, 1918). 



Fig. 197. Dientamoeba fragilis, X2300 (Kudo), a, b, living bi- and 

 uni-nucleate trophozoites; c, d, stianed uni- and bi-nucleate tropho- 

 zoites. 



D. fragilis J. and D. (Fig. 197). The trophozoite is actively amoe- 

 boid; 4-18/x (average 5-12/x) in diameter; progressive movement; 

 cytoplasm well differentiated; endoplasm granulated contains bac- 

 teria in food vacuoles; nucleus onl} r faintly visible; 1 or 2 nuclei, the 

 ratio is variable; in some material binucleate forms may be 80% or 

 more (Jepps and Dobell), while in others uninucleate forms may pre- 

 dominate (Kudo, 1926a; Wenrich, 1937); nucleus is made up of a 

 delicate membrane and a large endosome (more than one-half the 

 diameter of nucleus) in which are embedded 4-8 chromatin granules 

 along the periphery. According to Dobell (1940), the binucleate con- 

 dition represents an arrested telophase stage of mitosis and the 

 chromatin granules are in reality chromosomes, probably 6 in num- 

 ber. Comparison with Histomonas meleagridis (p. 335) led this author 

 to think that this amoeba may be an aberrant flagellate closely re- 

 lated to Histomonas. 



