80 
NOTES ON THE COMMON PATHOGENIC 
the cause. The Italian workers in Erythrea note that there 
is no tsetse in the affected area and that the suspected fly is a 
Tabanus or a Hippobosca. 
The Sleeping Sickness Commission of the Royal Society 
showed that Gl. palpalis, caught on the shore of Lake Victoria, 
was infected with T. vivax. Bouffard has shown that Gl. 
palpalis, of the Niger region in French territory, maintains a 
true cyclical development of this Trypanosome, that it became 
infected after so short a period as a week, and that it might 
remain infected for at least two and a half months after the 
infecting meal. 
In Northern Rhodesia no Gl. palpalis occurred within 200 
miles of where T. vivax appeared endemic. Gl. morsitans or 
other genera of biting flies ( Tabanus and Stomoxys) must be 
incriminated. 
Trypanosoma lewesi. Kent, 1881. 
Hosts. Mus rattus, Mus decumanus, and Mus rufescens. 
Lingard, in India, describes it as also occurring in M. ninieventer. 
Distribution. T. lewesi is widely distributed, especially in 
sewer rats, throughout the world. Stordy has noticed its 
occurrence in Mombasa, and at Kisumu I found it present in 
52 per cent, of the rats examined (November 1909). Bruce 
and Nabarro found it prevalent at Entebbe. 
Morphology. This Trypanosome measures about 25ya in 
length, including the flagellum, and about T5/jl in breadth. It 
is narrower than the free flagellated pathogenic forms — 
T. gambiense, &c. — and the undulating membrane is more 
poorly developed. 
Note. — The term 1 flagellated ’ is used to denote a trypanosome 
carrying a free flagellum, as opposed to a form (e.g. T. nanum, 
T. cryolense, tadpole T. dimorphon) which does not. These latter 
are usually very short trypanosomes and consequently are rela- 
tively narrow. 
In a fresh preparation the movement of T. lewesi is more 
rapid than in most other species, but it is not so great as in 
T. vivax. 
Biology. No animal species but rats appear susceptible to 
infection. A transitory infection lasting a few days can be 
