OF THE ALIMENTARY TRACT 147 



freely in liquid, revolving as it goes, crawling, twist- 

 ing and pushing its way through clumps of debris. 

 Its body is flexible and it may elongate, contract and 

 turn at will. When sluggish it may have surface 

 pseudopodia. It has four flagella attached at the 

 anterior end to a group of granules, the blepharo- 

 plast. It possesses an undulating membrane, the 

 border of which (axoneme) originates at the same 



Fig. 23. — Trichomonas hominis. 



Drawings of specimen unstained (A) and stained (B) by iron- 

 haematoxylon. x 2000. 



place as the flagella and may extend posteriorly as 

 a free flagellum. The base of the undulating mem- 

 brane is supported by a fibre of similar origin. The 

 flagella move in rythmic lashings, sweeping materials 

 against the ingesting surface, the undulating mem- 

 brane waving synchronously with the lashing of the 

 flagella. The undulating membrane extends di- 

 agonally posteriorly for the whole or greater part 



