482 



Col. Sir D. Bruce and others. Cattle as a [June 7, 



III. Can Cattle be Infected with Sleeping Sickness by the Bites of the 

 Naturalhj-infectecl Flies caught on the Lake-shore ? 



In the next three experiments freshly-caught Glossina palpalis brought up 

 to the laboratory from the Lake-shore were allowed to feed straightway on 

 healthy cattle. By this means it will be shown whether Glossina palpalis in 

 their wild state are capable of giving Sleeping Sickness to healthy cattle. 



Experiment 982. Bull. 



2195 freslily captured Glossina palpalis were applied to a bull, and of these 1536 were 

 estimated to have fed. This feeding of the flies extended over a period of 16 days, at the 

 end of which time Trypanosoma gamhiense appeared in the blood of the bull. 



To help in the identification of this trypanosome, 3 c.c. of the blood of the bull were 

 injected into a monkey. The monkey developed Sleeping Sickness 18 days later. 5 c.c. 

 of the blood of the bull were also injected into a goat. Trypanosmna gambiense appeared 

 in the blood of the goat after an incubation period of 38 days. 



Experiment 1462. Bull. 



The details of this experiment were similar to those of the last one. Over a period of 

 eight days, 1310 wild flies from the Lake-shore were applied to the bull, of which 705 fed. 

 Ten days from the first application of flies, Trypanosoma gamhiense appeared in the blood 

 of the bull. 



Two animals, a monkey and a goat, each received 1 c.c. of the blood of the bull by 

 injection under their skin. The monkey developed Sleeping Sickness seven days later, 

 but the goat died in 16 days without showing any infection. 



Experiment 1465. Bull. 



During a period of 13 days, 459 freshly caught Lake-shore Glossina palpalis were 

 applied to a bull, and of these 314 fed. On the fourteenth day after the flies were first 

 fed, the bull developed an infection of Trypanosotna gamhiense. 



Some blood from this bull was injected into a monkey and into a goat. Neither 

 animal became infected. 



Conclusioii. — These experiments prove that Glossina palpalis, when captured in their 

 natural state on the Lake-shore, are capable of transmitting the virus of Sleeping Sickness 

 to cattle, and tliat the blood of these cattle gives rise to a fatal form of the disease in 

 monkeys and in goats when it is injected into them. 



« 



IV. Is it possible to Infect Tsetse Flies by Feeding them on Cattle Infected with 

 Sleeping Sickness, and aftervMvds to (ransmit the Disease by means of these 

 Flics to Healthy Animals ? 

 Five experiments under this heading wore carried out. Laboratory-bred 

 flies were used in all of them. Three were negative and two positive. Tlie 

 three negative experiments will be shortly summarised first. 



