AMOEBINA 



353 



is still unknown. Mercier (1909) held that when the multinucleate 

 cysts gain entrance to the host intestine through its mouth, each of 

 the C3^st-nuclei becomes the center of a gamete; when the cyst- 

 membrane ruptures, the gametes are set free and anisogamj^ takes 

 place, resulting in formation of numerous zygotes which develop into 

 the hal)itual trophozoites. Among the more recent investigators, 

 Morris (1936) is inclined to think that sexual reproduction brings 

 about 'zygotic adults.' Meglitsch (1940) made an extensive cyto- 

 logical study of this amoeba. 



Fig. 166. a, Endamoeba majestus, X420 (Kirby); b, E. simulans, 

 X420 (Kirby); c, Entamoeba brasiliensis in Zelleriella, X290 (Stabler 

 and Chen). 



E. thomsoni Lucas. In colon of the cockroaches; 7-30^ in diameter; 

 very adhesive; 1-3 chromatin blocks on the nuclear membrane; 

 cysts 8-16m in diameter, with 1-4 nuclei. 



E. disparata Kirby. In colon of Microtermes hispaniolae ; 20-40/x 

 long; active; xylophagous. 



E. majestas K. (Fig. 166, a). In the same habitat; 65-165^ in 

 diameter; many short pseudopodia; cytoplasm filled with food 

 particles. 



E. simulans K. (Fig. 166, 6). In the gut of Microtermes pana- 

 maensis; 50-1 50/u in diameter. 



E. sahidosa K. In the same habitat; small 19-35iu in diameter. 



Four additional species have recently been described by Hender- 

 son from the colon of Cubitermes sp. of Africa. They are E. pellucida, 

 E. granosa, E. lutea, and E. suggrandis. 



Genus Entamoeba Casagrandi and Barbagallo (1895). Nucleus 

 vesicular, with a comparatively small endosome, located in or near 

 the center and with varying number of peripheral chromatin 



