122 PROTOZOAN PARASITISM 



DIENTAMOEBA FRAGILIS 



This is an uncommon amoeba of the human in- 

 testine, first described by Jepps and Dobell (1918). 

 It is small, 3I/2 to 12 microns, actively motile when 

 fresh and warm, with distinct ectoplasm and endo- 

 plasm, the pseudopodia being clear and "leaf-like." 



Fig. 22. — Dientamoeba fragilis. 



Drawings of trophozoites and cyst from specimens stained by 

 iron-haematoxylon. x 3000. 



The endoplasm contains bacteria upon which the 

 amoeba feeds. 



Characteristic of it are its two nuclei, although these 

 are usually invisible in unstained specimens. In 

 properly stained preparations the nuclei show a rim 

 with a scattering of small granules upon it, a central 

 karyosome of a group of chromatin granules, con- 

 nected with the granules on the rim by delicate 

 threads. 



Dientamoeba fragilis is an exceedingly delicate 

 organism, undergoing early degeneration and disin- 



