ENDOLIMAX NANA 



available no doubt a large proportion of mankind is in- 

 fected. The only method of reproduction is probably 

 binary division of the trophozoites. 



4. ENDOLIMAX NANA 



Trophozoite. This is a comparatively small species, the 

 trophozoite (Fig. 3a) measuring only 6)U to 12^1 in diam- 

 eter. It has clear, blunt pseudopodia but is usually slug- 

 gish. The food vacuoles contain bacteria and other food 

 bodies. The nucleus is like that characteristic of the 

 genus. 



Precystic stage. As in E. histolytica, the precystic stage 

 loses its food bodies, but does not become much smaller 

 than the adult trophozoite. 



Cyst. The cysts (Fig. 3b) are typically ovoidal but 

 sometimes spherical or irregular in shape. They are from 

 8/xto lO/zin length and about 6^1 m breadth. The fully de- 

 veloped cysts contain 4 nuclei but younger cysts with 

 I, 2, or 3 nuclei occur. No chromatoid bodies are present 

 but diffuse glycogen masses may occur from the pre- 

 cystic to the 4-nucleate stage. 



Life-cycle. E. nana probably lives only in the large 

 intestine of man and is present in about 25 per cent of 

 the general population. Increases in number no doubt 

 result from binary fission of trophozoites and from divi- 

 sion of the 4-nucleated cyst into 4 uninucleate amoebulae 

 when excystation occurs. 



5. lODAMCEBA WILLIAMSI 



Trophozoite. This is generally from g^i to I4)u in diam- 

 eter, although specimens have been reported that were 

 smaller or larger (Fig. 4a). There is no clear distinction 



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