FAUNA OF EAST AFIUCA. 1 1 



of ticks and forms a reservoir for East Coast fever, etc. They 

 thus urge the extermination of all the game. 



Tlie tsetse-fl.}' has probably restricted the settlement area, but 

 up to the piesent there has been no dearth of land free from this, 

 insect. To what extent the tsetse depends for its perpetuation 

 on wild game is not cpiite clear. I, personally, saw more tsetses- 

 than anywhere else in a bush area on the coast where hai-dly any 

 game existed ; then, again, there are tsetse-ha.unted areas on 

 the Kerio Iliver where the Tarkana tribe herd large numbers- 

 of donkeys and camels with impunity. The bionomics of this 

 insect need still more investigation, and it does not necessarily 

 follow that all the representatives of the genus Glossina carry 

 the disease. 



The tick question in Africa is really one of more importance,, 

 and why some areas literally swarm with these Arachnids, while- 

 others are but sparsely supplied, is a mystery. I do not know 

 if it is anything more than a. coincidence, but I have noticed 

 that the areas covered with black cotton soil contain far more 

 ticks than the sandy soils or red soil a,reas. The black soil cracks 

 a good deal in the dry season, and it is possible that these 

 cracks may form sheltei'S for some of the ticks when the grass 

 is fired, whereas in other areas the greater portion of the ticks 

 are annually destroyed by fire. 



The Athi and Kapiti Plains swarm with ticks, and the soil 

 there is a black clay formed by the weathei'ing of the iniderlying 

 sheet of phonolite, and which opens out into deep cracks during 

 drought. The Rift Valley soil is a light powdery volcanic dust, 

 and ticks ai-e by no means plentiful. In the light soil of the- 

 coastal region ticks are also not xevj numerous. 



There is no doubt that wild game is tolerant of the parasites, 

 which cause diseases such as East Coast fever and Redwa,ter 

 fever in cattle, and there is little doubt that the ticks become 

 infected by biting these hosts ; further, it is alleged that a tick can 

 engorge itself once in each of its three stages of existence, also 

 that in most cases when a tick engorges on an animal it cleans 

 itself — that is to say, its internal parasites, if any, are discharged 

 into the mammal upon which it feeds. Presumably if tliii^ 

 animal is already infected the tick absorbs a new crop of parasites 

 with its blood. 



It is also alleged that it has been proved that in some cases 

 ticks hand on their ]>arasites to their progeny. It will therefore 

 be seen that the problem is fairly complex. 



The veterinary authorities in East Africa and South Africa 

 have done a good deal of w'ork on the subject, but it appears to- 

 me that further investigation is necessary before we can her 

 dogmatic on these difticult questions. 



It must, moreover, also be borne in mind that if tlie big game 

 is exterminated in an area, there will always I'emain a supply 

 of ground game also presumably tolerant, which may keep the- 

 disease parasites alive. 



