On Flagellated Protozoa, &c. By Edgar M. Crookshank. 927 



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 Tricho- 

 monas* It seems to me therefore that they are embraced by the 



Fig. 199. 



Monads in rat's blood stained with methyl-violet, showing membrane uuder 

 different aspects, blood-corpuscles, some crenated, and stained discs (x 1200). 



old genus Trichomonas, and that there is no need to create a new 

 one, Htematomonas. The common habitat of these species may be 

 expressed by grouping them together in one sub-genus, Tricho- 

 monas 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, I should be inclined 

 to say that these organisms belonged to one and the same species, 

 ■which might well be named Trichomonas sanguinis. I have 

 shown that 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 has 

 never been isolated apart from the blood, and the disease then 

 produced by its introduction into healthy animals. It is quite 

 possible that the parasites in Surra are only associated with the 

 disease, the impoverished blood affording a suitable nidus for their 

 development, while the contaminated 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, 

 * Leuckart, ' The Parasites of Man,' trans, by Hoyle, 1886. 



