606 APPENDICES. 



both ends, 30 to 40 //, long and 1 to 1 1 /x, wide. May possess in 

 front a flagellum, arid on one side an undulating membrane. 

 'Species : 



Haematomonas cobitis. Body provided with a spiral membrane 

 and a flagellum at the fore-end. Parenchyma of body homogeneous. 

 Second variety, body and flagellum only. Movement undulatory, 

 body containing highly refractive spherules. Third variety, plasma - 

 like body, without membrane or flagellum ; quickly changes form 

 by sending out processes laterally, and contains two to four refractive 

 spherules. Blood of mud-fish. 



Haematomonas carassii. Long bodies, with narrow membrane 

 attached along the whole length ; less actively motile. Several 

 forms also observed strikingly smaller than the above ; many disc- 

 shaped. Often seen attached to a red corpuscle, setting them in 

 motion by their movements. Blood of carp. 



The morphological identity of the rat and Surra parasites has been 

 established by the author, and both ssem morphologically identical 

 with the organism of Mitrophanow. If we follow Mitrophanow, we 

 must obviously enlarge his genus of Hsematomonas. The author does 

 not agree with Mitrophanow in the advisability of adopting this 

 entirely new generic name. Mitrophanow suggested this new term 

 because of the special habitat, normal fish-blood, of the species he 

 discovered. But the characteristic features of these organisms are the 

 characteristic marks of the genus Trichomonas. It seems, therefore, 

 that they are embraced by the old genus Trichomonas, and that there 

 is no need to create a new one Haematomonas. The common habitat 

 of these species may be expressed by grouping them together in one 

 sub-genus Trichomonas sanguinis ; but the question arises whether 

 they are distinct species. If it were not for the different description 

 given by Mitrophanow of the organism in the mud-fish, the author 

 would be inclined to say that all these organisms belonged to one and 

 the same species, which might well be named Trichomonas sanguinis. 

 The monad in the rat and the Surra parasite are morphologically 

 identical with each other, and both, as far as one can judge from 

 the description, morphologically identical with the monad in the 

 blood of the carp. We have, however, seen that the organism in 

 Surra is believed to be pathogenic, and too much stress must not be 

 laid on morphological identity. There is strong evidence in favour 

 of believing in its pathogenic properties ; but at the same time it 

 must be borne in mind that the organism ha,s never been isolated 

 apart from the blood, and the disease then produced by its introduc- 

 tion into healthy animals. It is quite possible that the parasites in 



