No. 480] EXTINCTION OF MAMMALIA 



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'immunes' may act as reservoirs of disease organisms which 

 through flies or ticks may be carried to non-immunes. Thus the 

 wild ruminants of Africa among the Bovidae especially, the buffalo 

 {Bos (Bubalus) cajfer), the kudu {Strepsiceros kudu), the wilde- 

 beeste (Connochsetes) carry about in the fluid portion of their 

 blood, without themselves suffering any harm, certain protozoan 

 trypanosomes which are fatal when borne by flies to domesticated 

 horses (Rquidsc), dogs (Canidse), and cattle (Bovidje). 



Thus, causes favorable either to the genesis of these disease 

 organisms or to the acquirement of immunity, or to the pro[)aga- 

 tion and distribution of flies and ticks become matters of prime 

 interest m relation to extinction. 



T^(-h( Flif Dis(as( of Donuslnatid Lquida^ and Bovidoe —The 

 nagana or tse-tse flv disease of Africa is caused by Trypanosoma 

 brma (Pliinmer and liiadtoidl, tliecarriei is the tse-tse fl\ (G/09- 

 sma viorsitans). Together this trvpanosome and its host the 

 fly render thousands of s(|iuuv rnih's of Africa uninhabitable and 



