PROTOZOA IN THE DIGESTIVE TRACT 25 



commensal. It is another vei)^ common amoeba and widely 

 distributed. 



Trophozoites 



I. Living specimens. This amoeba (Fig. 5, l) is con- 

 siderably smaller than the four species already described. 

 It measures 6-15m in the largest diameter. The organism 

 is a fairly active amoeba as seen in fresh material. It pro- 





s 



Fig. 5. Endolimax nana. X 1150. (original) 

 1. A living amoeba. 

 2-4. Stained amoebae, 



5. A fresh cyst. 



6. A stained cyst. 



gresses slowlv bv forming a broad pseudopodium in the 

 direction of movement. When stationary, pseudopodia are 

 formed at different points of the body surface. In these 

 forms, the ectoplasm appears clearly differentiated from 

 the endoplasm which is granulated and contains bacteria 

 as solid food particles. The nucleus is not clearlv visible in 

 living specimens because the endosome assumes varied 

 appearances. 



2. Stained specimens. The body is rounded (Fig. 5, --i). 

 The reticulated cytoplasm contains bacteria, and is some- 

 times infected bv Sphaerita (p. 69). There is a vesicular 

 nucleus which measures about 1.5-3u in diameter. The 



