TRICHOMONAS HOMINIS 



649 



is swept out of the intestine. Its presence is not necessarily an indication 

 that it is the cause of any intestinal derangement which may exist. It 

 is a pear-shaped organism measuring 5 to 15 microns in length. Occa- 

 sionally longer forms are seen. The shape of the body, which is normally 

 pear-shaped, changes considerably from time to time, and under certain 

 conditions pseudopodia are formed. The anterior end of the body is 

 somewhat bluntly pointed, while the posterior end is more tapering and 

 terminates in the protruding axostyle. The flagella, which are as long as 



Fig. 266. — Trichomonas hominis from the Human Intestine ( xca. 2,000.) 

 (1-3, AFTER Faust, 1921; 4-6, after Wenyon and O'Connor, 1917.) 



1-3. Forms with three anterior flagella (Tritricliomonas) . 

 ■4-6. Forms with four anterior flagella [TricJiomoruts). 



or longer than the body, arise from the anterior extremity. These are 

 usually four in number. They move about from one side of the body to 

 the other, performing sweeping movements very much like the action of a 

 whip which is lashed to and fro. Very frequently the proximal portions 

 of the flagella appear adherent to one another or twisted to form a common 

 stem. On the ventral side of the base of the flagella is a slit-like cytostome. 

 There is a well-developed undulating membrane, which passes in a slightly 



