THE WILD FAUNA OF THE EMPIRE 25 



:and sleeping sickness, are due to minute organisms which are very 

 closely allied. In one case, the case of the disease which affects 

 domestic animals, those parasites have been found, undoubtedly, 

 in the blood of big game in Africa, and it has been found that 

 those parasites can be conveyed from the wild animals to domestic 

 animals by tsetse flics, and, so far as we know, by tsetse flies only. 

 Africa is the only continent in the world in which tsetse flies are 

 found, and it is perfectly true that tsetse flies, when they can, will 

 take a meal of blood : they are frequently found in the same places 

 as wild animals, on which they are seen to feed. Therefore people 

 have assumed that if you protect the big game you are necessarily 

 protecting tsetse flies. I venture to think, as a result of the study 

 which I have made of this question for the past three or four 

 .years, that that assumption is not justified by the facts. _ In the 

 first place, although you may get tracts of country which are 

 ■s warming with big game, it does not necessarily follow that those 

 tracts of country will contain tsetse fly at all ; in the second place, 

 with regard to sleeping sickness, we do not yet know which is the 

 natural host of this parasite which causes the disease. Tsetse flies 

 have been found in Uganda by the latest members of the Sleeping 

 Sickness Commission sent out by the Colonial Office and the Royal 

 Society, and those tsetse flies found in Uganda have been found 

 to contain very similar parasites which would be mistaken, by an 

 inexperienced person, for the parasites of the sleeping sickness, 

 but which were not those parasites, but distinct from them. On 

 the other hand, if you take tsetse flies and make them feed on 

 infected human beings or infected monkeys, or other animals, you 

 undoubtedly find that those tsetse flies do suck up the parasites, 

 and are capable of conveying them to other animals. The wild 

 tsetse flies are not, or extremely rarely, found to contain those 

 parasites. Therefore we do not yet know what is the animal 

 which conveys these parasites. 



With regard to tsetse-fly disease in animals, the kind of tsetse 

 fly which carries it certainly is not found in the parts of the 

 country which are most frequented by big game, such as Masai 

 Plains in British East Africa. It was said in the old days that 

 that was the case with regard to the Orange Colony, and that it 

 Was the haunt of the wild game. It was the haunt of the wild 

 game, but you never find tsetse fly there. Tsetse flies are only 

 found in the hot, moist river valleys. 



In the second place, as to the tsetse fly which carries sleeping 

 sickness ; at present the disease is only associated with one of the 

 eight different kinds that we know, and is perhaps more confined 

 to such definite tracts, as hot, moist river valleys, and margins 

 of lakes, than any other places. I was informed only the other 

 day, by a man who had returned from the Anglo-Egyptian. Sudan, 

 that the sleeping-sickness-carrying tsetse fly which is found in the 

 extreme south of the Anglo-Egyptian Sudan is confined absolutely 

 to the water's edge, and that you do not meet it more than a few 

 yards from the water. 



