122 RESEARCH IN PROTOZOOLOGY 



such as the guinea-pig, sheep and sloth (Hegner and Schumaker, 

 1928). All of these species have been grown in culture in which 

 they occur in large numbers. No doubt they are often overlooked 

 in fecal material because of their minute size and small numbers. 

 The genus Embadomonas was established for flagellates found by 

 MacKinnon (1911) in the intestine of the larvae of aquatic insects. 

 No doubt many other species of embadbmonads besides those 

 already described are inhabitants of both vertebrates and in- 

 vertebrates. 



The human intestinal flagellate Chilomastix mesnili belongs to 

 the family chilomastigid^. The morphology of this species 

 is not entirely clear, especially that of the cytostomal region. Species 

 of the genus Chilomastix have been recorded from many of the 

 lower animals but very little is known regarding their life-cycles, 

 methods of transmission and relation to their hosts. 



The family cercomonadid^ contains two interesting genera, 

 Cercomonas and Tricercomonas. To the former belongs C. lon- 

 gicauda which is a common coprozoic flagellate in the feces of 

 man and other animals. Tricercomonas intestinalis is a human 

 intestinal flagellate which has been recorded from various parts 

 of the world but does not seem to occur in a large percentage 

 of individuals. 



A number of interesting genera belong to the family tricho- 

 MONADiD^. Certain of these are discussed in Chapter XV. 

 Trichomonads have been described from the human mouth, in- 

 testine, vagina, and urinary tract. Species most easily obtained 

 for study are Trichomonas muris, that occurs in enormous num- 

 bers in the cecum of rats, and T. aug^usta of the frog. Many 

 mammals, birds, cold-blooded vertebrates and invertebrates serve 

 as hosts for species belonging to this genus. An interesting 

 problem concerning the human trichomonads concerns the generic 

 status of specimens possessing three, four and five flagella re- 

 spectively. Those with three flagella are sometimes placed in 

 the genus Trifrichomonas, those with five in the genus Pcnta- 

 trichomonas and those with four are retained in the genus 

 Trichomonas. Among the other genera that can probably be ob- 

 tained easily for study are Ditrichomonas that occurs in termites, 

 Eutrichom^istix reported especially from reptiles, and Polymastix 

 from the intestine of various insects and several other genera 

 from termites. 



