42 MANUAL OF HUMAN PROTOZOA 



diarrhoeic faeces, both the trophozoite and cyst occur, 

 but in formed faeces only cysts are present. In severe cases 

 of infection with this flagellate, an enormous number of 

 trophozoites appear to lie attached to the mucous mem- 

 brane of the duodenum so that there may occur disturb- 

 ances in the affected portion of the intestine. In some 

 cases, the flagellate has been reported from the gall blad- 

 der. But there is no definite evidence that it destroys the 

 intestinal epithelium. 



Trophozoites 



1. Living specimens. While the flagella lash actively, 

 the organism progresses a little forward with a sidewise 

 rocking motion. It is broadly pyriform (Fig. 11, 1), and 

 about 9-20m long by 5-10|j broad. The anterior end is 

 broadly rounded and the posterior part tapers into a 

 usually upturned sharp point. Seen from side, one (dorsal) 

 side is convex, while the other (ventral) side is flat or 

 slightly concave (Fig. 11, 2). The anterior half of the 

 ventral side is concave and acts as a sucking disc for 

 attachment of the organism to the intestinal epithelium. 

 The pellicle appears delicate, but the body form changes 

 little, except the contraction and expansion of the sucking 

 disc and bending of the posterior prolongation. The body 

 cytoplasm is hyaline and seldom contains any solid food 

 particles. The four pairs of flagella which in actively 

 moving individuals cannot be seen without a dark field 

 condensor, lash continuously. They may however be seen 

 in less active individuals. Lugol's solution brings them out 

 fairly distinctly and at the same time the two nuclei may 



