ANIMAL MICRO-PARASITES. 607 



Surra are only associated with the disease, the impoverished blood 

 affording a suitable nidus for their development, while the con- 

 taminated water may be the common source of the organism and of 

 the disease. On the other hand, the organism in the rat is found in 

 apparently perfectly healthy, well-nourished animals. The author 

 suggests that the parasites observed in the rat and hamster should 

 be named after 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, Lewisi, Evansi) membrane, ter- 

 minating in a rigid filament and an anterior flagellum. 

 Highly polymorphic. Habitat, the blood. 



Species. Trichomonas cobitis (Hcem,atomonas cobitis 



Mitrophanow) Mud-fish. 

 Trichomonas carassii (tfcematomonas carassii 



Mitrophanow) Carp. 

 Trichomonas Lewisi (Herpetomonas Lewisi 



Kent) Rat, hamster. 

 Trichomonas Evansi (Spirochceta Evansi 



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



H^MATOZOA OF THE FROG. 



Lankester described an organism which he had discovered in the 

 blood of the frog (Rana esculenta). It consisted of a minute pyri- 

 form sac, with the narrower end bent round on itself somewhat 

 spirally, and the broader end spread out into a thin membrane, 

 which exhibited four or five folds and was prolonged on one side into 

 a very long flagellum. The wall of the sac was striated, nucleated 

 and granular ; the membrane undulated during life, and the 

 flagellum was also motile. It was named Undulina ranarum, but 

 subsequently recognised as idnetical with Tnjpanosoma sanguinis 

 described by Gruby. In the same blood Lankester also discovered 

 little oblong bodies, in many cases attached to the end of the red 

 corpuscles, and suggested a geneticai connection with the Undulina. 



