30 GEOGRAPHICAL DISTRIBUTION. 



Congo. Turning to German East Africa, we find that records 

 are fairly numerous, but, as the map shows, they are far more 

 abundant than anywhere else in the valleys of the Zambesi and 

 Limpopo, which, as has been stated by many previous writers, 

 are the main strongholds of Glossina morsitans. Although still 

 or formerly occurring extensively in the northern and eastern 

 portions of the Transvaal, the Tsetse, as already explained,* doe^ 

 not enter the Orange River Colony ; but Glossina morsitans, pi'o- 

 bably in company with Gl. pallidipes, abounds in Zululand, at 

 least in the northern portion of that country between the Lebombo 

 Mountains and St. Lucia Lake. 



In conclusion, it may be stated that there can be little doubt 

 that species of Glossina will eventually be found to occur at 

 intervals throughout Tropical Africa, wherever the conditions are 

 suitable f and there is a chance of obtaining food. 



* See page 7. 



t See page 7. While the Tsetse recedes before the advance of 

 civilisation, this is not the case with regard to other blood-sucking 

 flies, some of which may ultimately prove to be capable of conveying 

 Trypanosoma brucei (see Chapter VII., Appendix E, page 303). It would 

 therefore seem to be highly desirable that investigations should be set on 

 foot without delay with a view to determining the geographical distribution 

 of the latter ; that is, that the endeavour should be made, on the lines of 

 Colonel Bruce's inoculation experiments, to discover in what regions of 

 Africa the parasite of Tsetse-fly disease is naturally present in the blood 

 of wild animals. For this purpose, as pointed out by Colonel Bruce (cf. 

 Chapter VII., Appendix A, p. 286) all wild animals should be examined, 

 and not merely those usually entitled "game." 



