928 Transactions of the Society. 



well-nourished animals. These points indicate many lines of 

 inquiry, and I must reserve for a future communication the results 

 of the examination of mud-fish, of keeping rats, known to harbour 

 the parasite, under observation, and of testing the pathogenic in- 

 fluence of the organism on other animals. Provisionally I would 

 suggest that the parasites observed in the rat and hamster should 

 be named after Dr. Lewis, Trichomonas Lewisi ; the organism in 

 the mule, camel, and horse after its discoverer, Trichomonas 

 Evansi; and that the names Trichomonas cobitis and Trichomonas 

 carassii should be substituted for the names of the species described 

 by Mitrophanow. Thus we should have added provisionally 

 to the 



Genus — Trichomonas. 



Sub-genus — Trichomonas sanguinis. Definition : Elongated 

 tapering bodies, provided with a spiral (T. cobitis), or 

 longitudinal (T. carassii, Leuisi, Evansi) membrane, termi- 

 nating in a rigid filament, and an anterior flagellum. 

 Highly polymorphic. Habitat the blood. 



Species. — Trichomonas cobitis (Rsematomonas cobitis 

 Mitrophanow) — Mud-fish. 

 Trichomonas carassii {ILsematomonas carassii 



Mitrophanow) — Carp. 

 Trichomonas Lewisi (Herpetomonas Lewisi 



Kent) — Eat, hamster. 

 Trichomonas Evansi — {Spirochseta Evansi 

 Steel) — Horse, mule, camel ; (pathogenic ?). 



I have made several observations upon the life history of these 

 rat organisms, and have distinguished globose, angular, non-fila- 

 mentous, bi-flagellate semi-circular, and disc forms. These elastic 

 disc-like bodies (fig. 198, d), apparently the encysted stage, appear 

 to be identical with certain bodies figured as associated forms by 

 Mitrophanow, another point tending to confirm the identity of 

 these organisms. These points also I must make the subject of 

 another communication, having already exceeded the limits of a 

 single paper. 



