OF THE ALIMENTARY TRACT 121 



one nucleus, have a definite cyst wall, and character- 

 istically show a more or less prominent refractive 

 body staining dark brown in iodine, thus causing the 

 designation of iodine cysts or 'T cysts." 



As in the case of Endolimax nana, carefully dif- 

 ferentiated stained specimens of this amoeba are 

 necessary for its identification. 



The nucleus is single in all stages, except the rare 

 occurrence of a bi-nucleated cyst. In the free stage 

 this body show^s a large central karyosome sur- 

 rounded by globules between it and the rim. In the 

 cyst the karyosome is on one side, the other being 

 occupied by the globular bodies. The glycogen body 

 is dissolved in the usual staining technique, leaving 

 a vacuole. 



Presumptive identification in practical stool diag- 

 nosis may be made on the following points: 



An amoeba resembling Endamoeha coli, usually 

 smaller, with no nucleus visible in the active form, 

 with cysts commonly misshapen, showing in iodine 

 preparation a large brown globule, and on careful 

 examination a single nucleus in the cytoplasm not 

 occupied by the glycogen. 



This amoeba is also knowm as lodamoeha wil- 

 liamsi and Entamoeba nana. It is a fairly conmion 

 inhabitant of the intestine, w^here it is a harmless lu- 

 men dweller, its visible food objects being bacteria. 



Thomson and Robertson (1925) report its cul- 

 tivation on the L. E. A. medium of Boeck and Drboh- 

 lav for fifty-six days. 



