1911.] The Transmission of Trypanosoma nanum (Laveran). 9 



From the above it would appear that the development of Trypanosoma 

 nanum in Glossina palpalis commences in the hind gut and extends forwards 

 vid the thoracic gut and proventriculus until finally the proboscis is reached. 

 The salivary glands are apparently not invaded by this trypanosome. A fly 

 with a negative proboscis is presumably not infective, this conclusion being 

 supported by the fact that on three occasions injection of positive 

 proventriculi failed to infect Goat 329. 



Fly No. 4 shows that flagellates may be well established in the proboscis 

 by the 25th day after the infecting feed, although apparently neither this 

 fly nor No. 6 accounted for the infection of Calf 232 on September 10 to 11. 



Fly No. 8 showed a few flagellates in the proboscis, while both 

 proventriculus and thoracic gut were negative, and the prove utricular 

 infection of fly No. 14 was relatively slight in conjunction with a swarming 

 proboscis. These suggest the possibility that infection of the proventriculus 

 may be merely a temporary invasion, while the flagellates are becoming 

 established in the proboscis, and not a permanent station, in which case the 

 condition of Fly 8 is intelligible. 



As regards the actual infecting fly in the above experiments the choice 

 rests between Nos. 8, 13, and 14. All three flies were fed on Calf 232 from 

 September 11 to 16, i.e. during the incubation period, and may thus have 

 derived their flagellates secondarily from this source. This applies especially 

 to Nos. 13 and 14. There is, however, no reason why both these flies should 

 not have become infected originally at the commencement of the experiment, 

 in which case differential diagnosis is impossible. In the case of flies Nos. 9 

 and 15 there can be little doubt that the flagellates were derived from 

 Calf 232. 



As regards the position of the flagellates in the proboscis, the labrum is 

 the chief seat of infection, enormous numbers being found in this situation. 

 In one instance only, fly No. 4, Table II, were trypanosomes observed in 

 small numbers in the hypopharynx. 



Conclusions. 



(1) That the trypanosome received from Sebwe Eiver* is Trypanosoma 

 nanum. 



(2) That this trypanosome can be transmitted by Glossina palpalis, the 

 proportion of positive flies obtained being relatively large, and indicating 

 that this fly may play an important part in the spread of the disease in 

 Uganda. 



* Sebwe Eiver is in Toro Province, Uganda Protectorate, in the neighbourhood of 

 Lake George. 



