1910. |] Reservoir of the Virus of Sleeping Sickness. 319 
Compare these results with those detailed in the ‘ Proceedings’ of the Royal 
Society, B, 1910, vol. 82, p. 374, Table III. Of the 42 experiments there 
described, only 8 (19 per cent.) were positive. The clean laboratory-bred 
flies were fed on Trypanosoma gambtense-infected monkeys in 36 of those 
experiments, in one case on a Sleeping Sickness patient, and in ane cases 
on oxen infected with the virus of Sleeping Sickness. 
Positive results were obtained from all the buck on at least one occasion, 
with the exception of bush-buck, Experiment 2372, and reed-buck, 
Experiment 2445. Only two experiments were carried out from these buck, 
one from each, viz., Experiments 2499 and 2476. In Experiment 2499 the 
flies were fed on the antelope 19 days after the trypanosomes had 
disappeared from its blood, as far as microscopical examination went. In 
Experiment 2476 the flies were non-infective to monkeys up to the 45th day 
after their first feed on the infected buck. This latter experiment was 
proceeding when the Commission left Uganda, and a positive result may yet 
have to be recorded. 
The most significant of the above observations is the one in which it is 
shown that 55 days after the last feed of infected Glossina palpalis on bush- 
buck, Experiment 2328, the blood of this buck was capable of infecting clean 
laboratory-bred flies, though Trypanosoma gambiense had never been seen in 
its blood. 
To illustrate how these experiments were carried out, full details of two 
are given. They are typical of the methods adopted. One positive and one 
negative experiment have been chosen. (See next page.) 
These experiments show that antelope of the water-buck, reed-buck, and 
bush-buck species, when infected with the virus of Sleeping Sickness, can 
transmit the infection to clean laboratory-bred Glossina palpalis. The 
infected antelope’s blood was, in one case, infective to Glossina palpalis for 
at least 81 days, and in another for at least 55 days. These experiments 
further show that the flies, when infected by the virus of Sleeping Sickness 
obtained from the blood of infected antelope, are capable of transmitting 
the virus to susceptible animals. 
