IX SYMPTOMS OF 'FLY' BITES 171 



domestic animal, introduces Into the blood of the 

 latter certain minute blood parasites (Trypanosoma), 

 which, though constantly present in the blood of wild 

 animals living in the "fly"-infested regions of Africa, 

 does them no harm. These Trypanosomes, if intro- 

 duced into the blood of domestic animals in any 

 quantity, at once set up a disease, which almost 

 always ends fatally. Catde when "fly-stuck" soon 

 begin to run at the eyes, and the glands behind the 

 ears and in the throat swell. Although continuing 

 to feed well, they become thinner and weaker day 

 by day, and should they be exposed to cold or wet 

 weather, their coats stare, as if they were suffering 

 from lung sickness. According to the number of 

 Trypanosomes in their blood, cattle will live a 

 shorter or longer time. They will succumb within 

 a month if kept constantly in country where tse-tse 

 flies are numerous during that time. On the other 

 hand, they will sometimes live for nearly a year if 

 only "stuck" by one or a few flies whilst passing 

 through a "fly "-infested belt of forest of small extent. 

 I have known a young ox, though it showed every 

 sign of having been impregnated with the "fly" 

 disease — possibly it had only been "stuck" by one 

 "fly" — to recover completely after remaining very 

 thin for more than a year. Horses and donkeys, 

 when "fly-stuck," run at the eyes and swell at the 

 navel, and soon get thin and lose all their strength. 



In 1877 I took three donkeys with me up the 

 Chobi. They lived in a swarm of tse-tse flies day 

 after day and all day long. The first of them to 

 succumb only lived a fortnight ; the second died in 

 five weeks ; but the third lived for nearly three 

 months, and carried a buffalo head back to my 

 waggons at Daka — some eighty miles from the 

 Chobl. 



For about ten days before the second donkey 

 died I remained in the same camp. By this time 



