DR. DEYSD ALE'S HYPOTHESIS. 173* 



57- 1878, F. B. F3mney. 



" The Geographical and Economic Features of the 

 Transvaal, the New British Dependency in South 

 Africa " (Proceedings of the Boyal Geogra'pMcal Society, 

 Vol. XXII.). 



" Zoutpansberg forms with Waterberg the northern 

 boundary of the State, lying to the N.E. . . . Many 

 parts of this district, as well as Waterberg, are infested 

 with the Tsetse-fly ; but there is scarcely need to 

 attach so much importance to this fact as is commonly 

 done, because the fly is merely a temporary and 

 ephemeral scourge, and always disappears with the 

 large game. 



" Many parts, which six years ago were known as Fly 

 country, are now entirely free, and therefore it may be 

 fairly hoped that the extinction of the pest is only a 

 matter of time" (p. 120). 



58. 1879. J. J. Drysdale, M.D. 



" On the Germ Theories of Infectious Diseases " 

 {Proceedings of the Literary and Philosojthical Society of 

 Liverpool, No. XXXIIL, p. 13, note). 



An early suggestion pointing to the true part played 

 by the Tsetse-fly in connection with fly disease. After 

 referring to the then recent discovery by Dr. Manson of 

 the transference of Fllaria sanguinis by mosquitoes, the 

 author adds the following footnote : — 



"It is possible that we have here an explanation of 

 the destructive power of the Tsetse-fly, for it may be the 

 intermediate host of some similar blood-parasite ; or it 

 may be the carrier of some infective poison. It is highly 

 improbable that any mere poison or venum should exi.st 

 so powerful as to cause the death of a large animal in 

 such small dose." 



59. 1879, Captain J. F. Elton. 



" Travels and Researches among the Lakes and 

 Mountains op Eastern and Central Africa" (London : 

 John Murray), pp. 278, 404. 



August, 1877. — Tsetse abounding at Livingstonia, at 

 the south end of Lake Nyasa (p. 278). 



Still a question whether the deaths and sickness of 

 cattle on the Unyarayembe route from the coast to Lake 



