54 RESEARCH IN PROTOZOOLOGY 



smithi and Eimeria eUipsoidalis. A number of problems are sug- 

 gested. 



Is the Trichomonas in the feces really T. rum'inantimn which 

 was described from the rumen? If so, it means that the parasite is 

 capable of living in both the stomach (rumen and reticulum) and 

 large intestine (cecum and colon). The specimens from both places 

 have three flagella. 



What is the other small flagellate present? It might be an En- 

 teromonas, Tricercornonas, or an Emhadomonas. Hegner and Schu- 

 maker (1928) described Emhadomonas ovis from sheep. This may 

 occur also in cattle. 



Giardia hovis was described by Fantham (1921) from the cysts 

 and trophozoites which he found in the rumen and duodenum of 

 cattle. Becker and Frye found that the measurements of the cysts 

 and the ratio of mean length to mean width corresponded closely 

 with those of Giardia lainblia of man. Measurements should be 

 made of the trophozoites with a view to comparing this Giardia 

 with the one in man, since the cow may serve as a natural reservoir. 

 Giardia cysts have been found also in the feces of goats and sheep, 

 but not at this laboratory. Giardia cysts from the cow might be fed 

 to sheep and goats to see if they will grow there. Incidentally, an 

 excellent stain for Giardia cysts is iron-hsematoxylin counter- 

 stained with Lyon's blue, which stains the cyst wall beautifully. 



Bu^tonella sulcata, a ciliate belonging to the isotrichid^, was 

 found by Jameson in the ceca of cattle, but never in other rumi- 

 nants. Cross-infection should be attempted with sheep and goats. 

 The cysts are present in the feces of approximately thirty per cent 

 of all calves, according to our experience. In unpublished experi- 

 ments it has been found that at least certain of the stomach 

 INFUSORIA of ruminants are mutually interchangeable. It would 

 not be surprising if other protozoa of ruminants showed similar 

 relatively loose host specificity. This would be of great biological 

 and economic significance if true of coccidia. 



Hegner (1924) discovered a Balantidium in sheep. He states 

 that it is considerably smaller than the one from the pig and man. 

 Here is a question of specificity which can be investigated by the 

 cross-infection method. 



It appears to be quite definitely established that there are at 

 least three species of Eimeria which may be found in cattle {Cf. 

 Becker and Frye, 1929), Eimeria zilrni, subspherical to spherical, 



