436 



PROTOZOOLOGY 



ism undergoes amoeboid movement by means of lobopodia and in 

 the latter the body is more or less elongated. Binary fission seems to 

 take place during the amoeboid phase only. Thus these are diphasic 

 amoebae, in which the amoeboid stage predominates over the 

 flagellate. The amoeboid phase is often a 'limax' form; under natural 

 circumstances, it is often exceedingly difficult by observing the 

 amoeboid stage only, to determine whether they belong to this fam- 

 ily or the family Amoebidae. 



Genus Naegleria Alexeieff. Minute flagellate stage with 2 flagella; 

 amoeboid stage resembles Vahlkampfia (p. 442), with lobopodia; cy- 

 toplasm differentiated; vesicular nucleus with a large endosome; 

 contractile vacuole conspicuous; food vacuoles contain bacteria; 

 cysts uninucleate; free-living in stagnant water and often coprozoic. 

 Taxonomy and cytology (Rafalko, 1947; Singh, 1952). 



Fig. 183. a-c, trophozoite, flagellate phase and cyst Call stained) of 

 Naegleria gruberi, X750 (Alexeieff); d-f, similar stages of N. bistadialis, 

 X750 (Kiihn); g-j, trophozoite, flagellate phase, cyst, and excystment of 

 Trimastigamoeba philippinensis, X950 (Whitmore). 



N. gruberi (Schardinger) (Fig. 183, a-c). Amoeboid stage 10 36jtt 

 by 8-18/*; cyst uninucleate; cyst wall with several apertures; flagel- 

 late stage 18/x by 8/t; stagnant water and often coprozoic. 



N. bistadialis (Puschkarew) (Fig. 183, d-f). Similar in size; but 

 cyst with a smooth wall. 



Genus Trimastigamoeba Whitmore. Flagellate stage bears 3 

 flagella of nearly equal length ; vesicular nucleus with a large endo- 

 some; amoeboid stage small, less than 20/x in diameter; uninucleate 

 cysts with smooth wall ; stagnant water. 



T. philippinensis W. (Fig. 183, g-j). Amoeboid stage 16-18/x in 

 diameter; oval cysts 13-14/x by 8-12/t; flagellate stage 16-22/t by 

 6-8m. 



