RIVER, EAST AFRICA PROTECTORATE. 277 



duiker, lion, leopard, eheetah, serval cat, wart-hog, baboons and other monkeys, 

 hares, and numerous other small mammals ; also birds, such as guinea-fowl and 

 franeolin, but few large water-birds. 



In the fly-area blood smears were obtained from topi (probably the most 

 plentiful game animal), impala, zebra, wart-hog and a hare. On examination 

 later, none of these was found to contain trypanosomes. 



Conclusions. 



The tsetse-fly area on the Amala river appears to present several points of 

 interest : — 



(1). The species of tsetse-fly is the western Glossina fusca, which has never 

 been recorded previously from the East Africa Protectorate. 



(2). The altitude, 5,200 ft., is the highest at which any species of Glossina has 

 at present been found to exist permanently." 



(3). The fly on the upper part of the river, the area under discussion, is 

 apparently confined to the west bank, or only occasionally strays to the east 

 bank. 



(4). Natives with their cattle, sheep and goats have been living for many years 

 practically in contact with the fly (I have myself seen large numbers of cattle 

 grazing within 400 to 500 yards of belts of bush in which tsetse-fly undoubtedly 

 exist all the year round), in spite of the fact that several visiting sportsmen 

 have lost mules and trek-oxen as the result of an expedition down the Amala 

 river, and that the natives themselves admit that they occasionally lose a few 

 cattle from the bites of tsetse-fly (Endorobo). 



(5). There appear to be two possible explanations of the phenomenon of 

 natives with their cattle living among fly-areas in which at least a percentage of 

 the flies are known to be infected with a trypanosome pathogenic to cattle, mules 

 and horses : — 



(a) It is possible that the natives in this district are so familiar with the 



distribution of the tsetse-fly that they scarcely ever expose their 

 cattle to infection. The fly certainly appears to be confined to very 

 definite and distinct areas and it has been stated that if the natives 

 are at times compelled to visit these areas for water, this only occurs 

 during very dry weather when the fly is least numerous and active. 

 Where the escarpment on the west bank is within about two miles of 

 the river, the Masai have their villages and cattle kraals on the top 

 of the escarpment, only bringing their cattle down to water. This, 

 however, is above the fly-area. 



(b) It is possible that only a very small percentage of the tsetse- flies present 



are infective. This might be accounted for in two ways. Either 

 the reservoir or source of infection is very limited, or owing to 

 unfavourable climatic conditions (possibly the rather high altitude), 

 the flies themselves have very little power of what Koubaud calls 



# [Roubaud has recorded (Bull. Soc. Path. Exot. vi, no. 5, 14th May 11)13) that in the Paris 

 Museum there are many specimens of the fmcipes form of G. palpalis collected by Cronier on 

 the volcanos of Kivu, in the Belgian Congo, at an altitude of 5,000 to 5,500 feet. — Ed.] 



