PROTOZOA IN BRITISH EAST AFRICA 
27 
prolonged search. Glossina morsitans is very prevalent in this 
valley, and Gl. fusca also occurs, and these species are to be 
incriminated until their innocence be proved. 
It is highly imperative that experiments with other biting 
flies and with Tryp. gambiense should be conducted in order 
to confirm the observation of Kleine that Gl. morsitans does 
not act as a definite host. Stephens has suggested that the 
human trypanosome of Northern Rhodesia is not T. gambiense , 
but a new species which he calls T. rhodesiense. If this be 
substantiated the transmission by flies other than Gl. palpalis 
would be explained. 
Trypanosoma dimorphon. Dutton and Todd, 1903. A 
parasite of domestic animals. 
Distribution. Originally described from the Gambia, this 
— or allied and confused species — has since been shown to be 
widely distributed in Africa. I have specimens from Mambrui 
near Malindi, which are morphologically indistinguishable. 
Hosts. Horses, cattle, sheep, goats, dogs and possibly 
pigs. 
Morphology. The original description of Dutton and 
Todd defines the species as occurring in three forms, i.e. a 
very short or ‘ tadpole/ a medium or 4 stumpy,’ and a ‘ long ’ 
form which carries a free flagellum. In the strain brought 
to Europe, Laveran and Mesnil, and Thomas and Breml 
failed to find the free flagellated forms. Considerable con- 
fusion has resulted from this dual description, and species 
not answering to type have been recorded as T. dimorphon. 
The strain carried to Europe was not that studied by Dutton 
and Todd, and it is consequently most probable that it repre- 
sents a distinct species for which the name T. confusum, 
Montgomery and Kinghorn, was suggested. * Tadpole ’ forms 
measure from 11/* to 13/*, ‘ Stumpy ’ forms 16/* to 20/*, and 
the ‘ Long’ forms vary from 15/* to 30/*, of which 5/* to 10/* is 
taken up by the free flagellum. It is usual for ‘ Tadpole ’ 
forms to predominate during the earlier period of disease ; 
the long free flagellated forms becoming numerous only towards 
death. 
The differential diagnosis of T. dimorphon from species 
