50 PROBLEMS FOR INVESTIGATION. 



various statements on the distribution of Tsetse-flies and of 

 the eponymic malady disseminated by them. From Sir Harry 

 Johnston's great woi'k on "The Uganda Protectorate" [172], 

 published a few months ago, it appears that although " flies of 

 the genus Glossina ".* are found in that country, Tsetse-fly 

 disease is absent, a statement that suggests the advisability of 

 prosecuting a careful enquiry into the geographical distribution 

 of Trypanosoma hrucei without delay. f Reference may also be 

 made to a recent statement by Mr. J. N. Justice [l73]) who, in 

 a paper on " Prospecting in Northern Rhodesia," mentions that, 

 according to the natives, " since the rinderpest exterminated the 

 buflalo, the Tsetse has lost much of its venom. . . ." This is 

 merely a reassertion in another form of the old stories of the 

 specially close connection between the Tsetse and the buffalo, 

 Avhich, as may be seen from the letters printed in Chapter VII., 

 Appendix C, is not admitted as regards East Africa by some 

 of those best qualified to express an opinion on the subject. 

 Finally, we may notice two papers [XXVI., 174], by Dr. Franz 

 Stuhlmann on Tsetse-flies (Glossina morsitans and Gl. fusca) and 

 Tsetse-fly disease (which the author, like other recent German 

 writers, calls " Surrah") in German East Africa; in the former 

 paper Dr. Stuhlmann gives a map to illustrate the occurrence 

 of the disease in the region in question. 



In conclusion, then, it will have been seen from the foregoing 

 resume, that while in the space of sixty odd years our know- 

 ledge of the Tsetse-flies has gradually increased, we have still 

 much to learn. It is only within the last few years that the 

 remarkable mode of reproduction has been made known, and it 

 has yet to be discovered whether this is the same in all species. 

 Very little is known as to the distribution of certain species ; 

 and, most important of all, we are still in almost complete 

 ignorance as to whether all the species are equally capable of 

 conveying the parasite of Tsetse-fly disease (sec Chapter VII., 

 Appendix E, p. 300). 



II.— Systematic. 



Although the name " Tsetse " did not become generally 

 known in England until the year 1850, when the habits and 

 ravages of "the fly called 'Tsetse'" were mentioned ))y R. 



* Probably Gl. fiisca, Walk., and perhaps 67. iwllidipcs, Austen, 

 t Cf. Chapter I., p. 30, note f- 



