366 Mammalian Trypanosomes of A friea 
507 palpalis caught on the now uninhabited shores of Lake Kiraro near 
Lake George, infected a clean monkey with a trypanosome of the brucei 
group. There is a possibility that a few pallidipes may have been included 
in these flies from Kiraro, where game of many kinds is very common. I hope 
to revisit this locality and settle the important point whether palpalis is here 
carrying a brucei- like organism. 
Palpalis regions elsewhere in Africa are characterised by similar trypano¬ 
somes, and often, in addition, by the human parasite T. gambiense. The 
strains isolated by Dutton and Todd in the Congo from game and stock 
doubtless included representatives of all three groups, although these ob¬ 
servers held that only one species was present. In those days the term 
T. dimorphon seems to have included several different species, including 
doubtless T . uniforme and the nanum-pecorum group. 
The reactions of the polymorphic trypanosomes recovered by Dutton and 
Todd from game and stock were of the chronic gambiense type; they were 
held by these observers to be identical with T . dimorphon (Dutton, 1907). 
In Principe, where palpalis occurred under unique conditions, the same 
organisms were recovered from fly and cattle, and here again the repre¬ 
sentative of the polymorphic group gave the laboratory reactions of T. gam¬ 
biense (Da Costa, 1916). 
In Uganda, therefore, the trypanosomes most commonly carried by 
G. palpalis are T. vivax, T. uniforme and the polymorphic organism referred 
to throughout this paper. Broadly speaking, where T. brucei or T. pecaudi 
are found in palpalis areas in Africa another tsetse species will be found to 
occur in that area. As Avill be seen later there appears to be an important 
exception, the significance of which will be discussed later on. Trypanosomes 
of the nanum-pecorum-congolense type occur in the palpalis of certain inland 
areas, but not of Lake Victoria. 
PART III. ANIMAL REACTIONS OF THE UGANDA LAKE-SHORE 
POLYMORPHIC TRYPANOSOMES. 
An important difference between freshly isolated strains of T. gambiense 
and of T. brucei has always been the relative chronicity of the former in 
laboratory animals. 
In this section the animal reactions of the present-day lake-shore trypano¬ 
somes of Uganda are considered, the organisms being grouped according to 
their provenance into wild-fly, human, and antelope strains. 
In the subjoined tables M, S, D, P and R stand for monkey, sheep, dog, 
guinea-pig and rabbit respectively. No rats were available. 
(a) Wild-fly strain, Mainland. 
This strain was recovered from wild lake-shore flies from the mainland 
near Entebbe. The reactions in monkeys are shown in Table I. 
