AMOEBINA 443 



Several species. Volkonsky (1933) distinguishes four groups. Species 

 and morphology (Singh, 1952); nuclear division (Jollos, 1917). 



H. hyalina (Dangeard). 20-25/z in diameter; ectoplasm well 

 developed; endoplasm vacuolated; slender pseudo podia extend in 

 different directions; Hartmann and Chagas observed a centriole in 

 the endosome. 



Genus Acanthamoeba Volkonsky. Small amoebae similar to Hart- 

 mannella; ectoplasm is not well developed; mitotic figure at the end 

 of metaphase, a straight or concave spindle with sharply pointed 

 poles. Cysts enveloped by two membranes, the outer envelope being 

 highly wrinkled and mammillated. Several species. 



A. castellanii (Douglas) (Fig. 186, g, h). In association with fungi 

 and certain bacteria; Hewitt obtained the organism from agar cul- 

 tures of sample soil taken from among the roots of white clover; co- 

 existing with yeast-like fungi, Flavobacterium trifolium and Rhizo- 

 bium sp.; 12-30/x in diameter; some cysts are said to remain viable 

 at 37°C. for 6 days. 



A. hyalina (Dobell and O'Connor) (Fig. 186, *, j). According to 

 Volkonsky, the organism described by Dobell and O'Connor as 

 Hartmannella hyalina, is transferred to this genus. Small amoeba; 

 9-17yu in diameter when rounded; a single contractile vacuole; binary 

 fission; mitotic figure a sharply pointed spindle. Cysts spherical; 

 10-15/x in diameter; with a smooth inner and a much wrinkled outer 

 wall; easily cultivated from old faeces of man and animals; also in 

 soil and fresh water. 



Genus Sappinia Dangeard. With two closely associated nuclei. 



S. diploidea (Hartmann and Nagler). Coprozoic in the faeces of 

 different animals; pseudopodia short, broad, and few; highly vacu- 

 olated endoplasm with 2 nuclei, food vacuoles, and a contractile 

 vacuole; surface sometimes wrinkled; the nuclei divide simultane- 

 ously; during encystment, two individuals come together and secrete 

 a common cyst wall; 2 nuclei fuse so that each individual possesses 

 a single nucleus; finally cytoplasmic masses unite into one; each 

 nucleus gives off reduction bodies (?) which degenerate; 2 nuclei 

 now come in contact without fusion, thus producing a binucleate 

 cyst (Hartmann and Nagler). 



Family 3 Endamoebidae Calkins 



Exclusively parasitic amoebae; the vegetative form is relatively 

 small and occurs mostly in the alimentary canal of the hosts; con- 

 tractile vacuoles absent, except in Hydramoeba; multiplication by 

 binary fission; encystment common. The generic differentiation is 



