18 
THE QUESTION OP THE RELATION OF 
that the presence or absence of game has little or nothing to 
do with the distribution of tsetse flies. 
Besides this, there is absolute proof that tsetse flies will 
in nature feed upon birds and reptiles when they cannot obtain 
mammalian blood. 
In Uganda the Sleeping Sickness Commission of the Royal 
Society 1908-10 examined the stomach contents of numbers 
of wild Glossina palpalis caught on the lake shore. In a 
considerable number remains of blood were found which was 
sufficiently undigested to allow of the nucleated corpuscles 
being distinguished from the non-nucleated (i.e. the avian, 
reptilian, and amphibian from the mammalian). In this way 
it was proved that many of the Glossina pal'palis on the shores 
of Lake Victoria feed naturally upon birds, or crocodiles, 
lizards and snakes, or frogs and toads. In the laboratory, 
however, it was found that Glossina palpalis fed with more 
avidity on birds than on monkeys, while they could hardly 
be tempted to feed upon young crocodiles or lizards (‘ Sleeping 
Sickness Bulletin/ No. 19, p. 245). The possibility of separating 
avian blood corpuscles from reptilian or amphibian under the 
above circumstances is of course open to doubt (‘ Sleeping 
Sickness Bulletin,’ No. 82, p. 445), but the important fact 
remains clearly proved, namely, that the blood upon which 
the flies had fed was not mammalian, and was either avian, 
reptilian, or amphibian. 
Further experiments were carried out in Uganda by this 
Commission to ascertain if Glossina palpalis would feed on 
lizards or frogs. ‘ None of these experiments were very success- 
ful, and generally a large proportion of the flies were devoured 
before they could attempt to feed ; even when the caged 
flies could bite in safety they did not do so. Escaped flies, 
however, fed on chameleons, a number of which were kept 
in the laboratory for the purpose of catching flies. And flies 
were observed at least on one occasion sucking the blood of 
a lizard ’ (‘ Sleeping Sickness Bulletin,’ No. 82, p. 445). 
The discovery of Roubaud that Glossina palpalis will readily 
bite large caterpillars is of great importance, for if tsetse 
flies can feed upon the fluids of caterpillars, and perhaps other 
insects, it will help to explain a phenomenon which has always 
