CERCOMONAS HOMINJS 



6l 



as follows, according to the number of flagella and the presence or 

 absence of an undulating membrane : 



(1) Cercomonadida, with one flagellum at the anterior extremity, 

 without an undulating membrane. 



(2) BodonidcK, with two flagella, without an undulating membrane, 

 except in Trypanoplasma. 



(3) Tiypanosomidce t with one flagellum, and an undulating mem- 

 brane along the length of the body in some genera. 



Family. Cercomonadidae, Kent emend. Biitschli. 

 Small uniflagellate forms, without cytostome. 



Genus. Cercomonas, Dujardin emend. BUtschli. 

 Oval or rounded organisms, with the aflagellar end often drawn 

 out into a tail-like process. 



Cercomonas hominis, Davaine, 1854. 



Davaine found flagellates in the dejecta of cholera patients. They 

 had pear-shaped bodies, lengthening to a point posteriorly. Their 

 length was from 10 //, to 12 //,, and a flagellum about twice as long as 

 the body projected from one extremity (fig. 21). A nucleus was 

 hardly recognizable. Occasionally a somewhat long structure (cyto- 

 stome ?) appeared at the anterior extremity. The animals moved with 

 remarkable activity. They also attached themselves by means of their 

 posterior extremities and swung about around the point of attachment. 

 Davaine found a smaller variety, only about 8 yn long, in the dejecta 

 of a typhoid patient (fig. 21, 6). 



FIG. 21. Cercomonas hominis, Dav. a, larger, 

 t>, smaller variety. Enlarged. (After Davaine.) 



FIG. 22. Cercomonas hominis > 

 Dav. From an Echinococcus 

 cyst. (After Lambl.) 



The Flagellata observed by Ekeckrantz (1869) in the intestine of man belong to 

 this form at least to the larger variety and Tham (1870) reported fresh cases soon 

 after. Lambl's publication of 1875, which was written in Russian, and became known 

 through Leuckart's work on parasites, also alludes to apparently typical Cercomonads, 

 which, however, were discovered, not in the intestine, but in an Echinococcus cyst in 

 the liver (fig. 22). The elliptical, fusiform, rarely pear-shaped or cylindrical bodies 

 of the parasites measured 5 i*. to 14 /j. in length, and were provided with a flagellum 

 at one end, while the other extremity usually terminated in a long point. An oral 

 aperture occurred at the base of the flagellum, and there were one or two vacuoles 

 near the posterior extremity. Longitudinal division was also observed (fig. 22). 



