PARASITES 



351 



Walker (42) describes three other amoebae from the intestinal tract of 

 the mouse, namely: Amoeba cyiterica, A. musculi, and A. Jecalis. 



Flagellates 



Trichomonas muris (grassi, 1879). — T. muris may well be classed as 

 one of the most common intestinal protozoa of the house mouse. In the 

 above mentioned work of Harkema it was found in the caecum of 30.95% 

 of the mice examined. 



Wenyon (43) describes T. muris in the mouse as a pear-shaped organism 

 in the trophozoite stage varying from 3 /i to 20/x in length (Fig. 136). There 



Fig. 135. 



-Endamoeha muris from the rat (X1500). 



W enrich.) 



B. 



A, Trophozoite; B, cyst. {After 



are three anterior flagella and an undulating membrane bordered by an 

 axoneme which continues as a posterior flagellum. In the anterior region 

 are located the oval nucleus, a slitlike cytosome, and two groups of closely 

 aggregated blepharoplasts. The flagella arise from the most anterior one 

 of the blepharoplasts, and posteriorly from them extends the axostyle which 

 terminally protrudes as a short point. Food vacuoles containing bacteria 

 are found in the cytoplasm. Reproduction is by longitudinal fission or 

 multiple segmentation. 



Cysts of T. muris have been described by Wenyon as about 6 )U to 8 ^l 

 in diameter. He stated that it is difficult to judge whether or not the 

 organism is encysted since the flagellates may become spherical and quies- 

 cent in passed feces although not forming a cyst. 



Although trichomonads cause disorders or have been accused of causing 

 disturbances in man and some lower animals, no pathological condition has 

 yet been attributed to T. muris. 



Hexamita muris (grassi). — This (Fig. 136) is also a rather common 

 flagellate which occurs in the intestine of mice and rats. It possesses six 



