204 A NATURALIST IN MID-AFRICA. 



the female after this commences to feed ; then I 

 supposed that she laid her eggs and died. Dragon- 

 flies and a kind of sand-wasp are the only creatures 

 that prey upon them, to my knowledge. 



Still, the association of malaria with the mosquito 

 suggests the remark that there are numerous 

 places in Africa where (to my own knowledge) fever 

 is very bad and mosquitoes almost or altogether 

 absent (Tanganyika). There are also many places 

 in which mosquitoes abound and yet fever is not 

 present at all or very rare (Salt lake). 



The answer, of course, may be that, when one 

 enters Tropical Africa, the mosquito belt must 

 inevitably be passed through, and it is very possible 

 that the germs are in reality present for months 

 before unfavourable conditions of health bring 

 matters to a crisis. 



Fever is most usually produced by a chill, usually 

 the result of sitting or sleeping in damp clothes, 

 but it may be produced, as I know from experience, 

 by sunstroke or over-exertion. It is a general 

 theory amongst planters everywhere that clearing 

 a jungle results in fever ; and I have heard, e.g., in 

 the Shire highlands, so many instances of this that 

 I am disposed to believe in it. It does not seem 

 to be generally known that malarial fever occurs 

 amongst animals, but I think this is the case 

 amongst cattle, dogs, and even poultry and tur- 

 keys ! * 



* I have heard so on good authority in Tamatave. 



