300 



PARASITIC PROT(»ZOA IN KPXATION TO THE WAR. 



cyst wall of E. coli is often thicker than that of E. histolytica. 

 Chroniidial or chromatoid blocks are seldom present in the cysts 

 of E. coli, but if present, they frequently have pointed ends. Red 

 blood-corpuscles are rarely, if ever, ingested by the trophozoites 

 of E. coli. 



It has recently been claimed that another non-pathogenic 

 species, E. nana, may occur in the human^ intestine. Its tropho- 

 zoite is small and vacuolated, containing ingested bacteria, and it 

 has a distinctive nuclear structure. Its cysts when mature are 

 usually quadrinucleate, being oval or sometimes spherical, and 

 measuring S^tt to iO/>t by y^i. to 8u Chromatoid bodies are said to 

 be absent from the cysts. 



Free-living amceb?e of the Umax group may also be foimd 

 occasionallv in human stools. 



Fig. 3. 



Vv*. 4. 



Intestinal Flagellates. 



The Mastigophora found in stools have already been men- 

 tioned, and may now be briefly described. 



TrichoiHOiias hominis or 7". intcstiiialis, as found in the 

 human intestine is pear-shaped, with three free flagella at the 

 blunt or anterior end. There is also a lateral flagellum attached 

 to the body by an undulating membrane, and an axial rod running 

 towards the pointed end of the body from near the anteriorly 

 placed nucleus (Fig. 4). The flagellate measures about io,u to 

 ^5/* t)y 5/A to lOfjL. Rounded contracted forms may be found in 

 the faeces. Similar trichomonads occur in rodents, such as rats, 

 mice, and rabbits, and also in cats. Possibly rats and mice act 

 as reservoirs of the parasites. Trichomonads may also be water- 

 borne. Mello Leitao (1913) found T. hominis in cases of rela- 

 tively benign dysentery in Rio de Janeiro. Escomel (1913) found 

 152 cases of dysentery in Peru solely due to trichomonads. Tri- 

 chomonas was found by Fantham and Porter in some patients 

 from Gallipoli, while in certain cases at Suez this flagellate was 

 the cause of diarrhoea. With regard to treatment, the use of tur- 



