1906.] Glossina palpalis and Trypanosoma gambiense, etc. 



251 



drying themselves in the sun on the trees, and especially on the ambatch 

 trees, where the flies are found in swarms. These birds might furnish one 

 constant and important source of food. We found in the laboratory that 

 tsetse-flies fed very rapidly on captive fowls, creeping under their wings to 

 bite the poorly protected parts of the skin. On the other hand, when a heap 

 of recently shot water-birds, some of which were hardly dead, were lying 

 on the lake-shore at Kimmi Island, the swarms of tsetse-flies did not attempt 

 to settle on them, although freely biting us and our servants. A second 

 possible source of food supply is furnished by the aquatic animals of the 

 lake-shore, such as the hippopotamus, the otter, the crocodile and the python. 

 We have definite evidence that the fly feeds on the hippopotamus and on the 

 crocodile. Flies were caught in the act of biting a hippopotamus just 

 recently shot, settling chiefly on the ears and nose. We, therefore, made 

 blood-films and had blood-films sent us of as many aquatic birds and animals 

 as possible, including five or six hippopotami. Only in a single case did we 

 find a trypanosome, namely, in a not very well preserved film of crocodile's 

 blood ; beyond its large size and general resemblance to other reptilian 



A B C 



Fig. 1. — Hsemogregarine in the red blood-corpuscles of the crocodile, x 2000. 



trypanosomes, it was not possible to make out any details of structure in 

 this parasite. We may mention, however, that the blood of many of the 

 birds contained Halteridia, and that a Hsemogregarine was quite common in 

 the blood of the crocodiles (fig. 1). We also observed that flies in captivity 

 sucked the blood of lizards, chameleons and snakes very freely. 



There are, therefore, two possible sources for the trypanosomes in the 

 freshly caught tsetse-flies. Either they are taken up from some of the 

 numerous animals upon which the fly feeds, or they may be parasites of 

 the fly itself, like Herpetomonas muscce-domesticce in the house-fly. In this 

 respect it is interesting to note that a small percentage of another common 

 blood-sucking fly in Uganda (Stomoxys sp.) contain a species of Herpetomonas 

 very similar to that of the common house-fly in Europe. With regard to 



