Protozoa o£ the Digestive and Urogenital Tracts 549 



hominis. Trichomonads apparently identical with P. hominis have been 

 found in monkeys, cats, dogs, and rats (171). 



The flagellate (Fig. 11. 3, A-C) measures 8-15x3-5[j.. The undulating 

 membrane is about as long as the body and there is usually a free 

 posterior portion of the membrane-flagellum. The fifth flagellum, which 

 may be trailed posteriorly, beats in a rhythm different from that of the 

 other four anterior flagella (103). A costa extends beneath the base of 

 the undulating membrance and the axostyle usually projects beyond the 

 posterior end of the body. Encysted stages are unknown. 



Fig. 11. 3. A. Pentatrichomonas hominis, showing five anterior flagella, 

 membrane flagellum, nucleus, axostyle and costa; x2530 (after Wenrich). 

 B. P. hominis, larger specimen with several food vacuoles; costa not shown; 

 x2400 (after Wenrich). C. Bodian silver preparation of P. hominis, showing 

 pelta anterior to the nucleus and a dorsal filament extending posteriorly 

 from the pelta, between the costa and the nucleus; x2040 (after Kirby). 

 D-G. Giardia lamblia: dorsal view (D), ventro-lateral view (E) of flagellate; 

 cysts with four (F) and twelve (G) nuclei; x2560 (after Kofoid and Swezy). 



