CONVEYANCE OF PAEASITE. 301 



numbers.* The flies were not actually observed attacking the 

 cattle, but they probably did so since they bit my two com- 

 panions and myself when seated on the seashore hard by. It 

 is but fair to mention that, with the exception of a few small 

 buck, there are no wild animals of any size near Free Town 

 which might afford sustenance to the Tsetse and at the same 

 time harbour the Trypanosoma But this is not the case in 

 Uganda, where, according to Sir Harry Johnston [172], " nearly 

 every known type of African antelope is represented," not to 

 mention buffalo, giraffes, and zebras, while Glossina (species as 

 yet undetermined) also occurs there, although Tsetse-fly disease 

 is absent. With regard to Uganda, Sir Harry Johnston suggests 

 that " either the true Tsetse is absent from all parts of the 

 Protectoi'ate, or it is unable to obtain there the germs of fever 

 which it is the agent in introducing to the blood of horses, 

 cattle, and other beasts." By " the true Tse-tse," Sir Hariy 

 Johnston doubtless means Glossina morsitans, Westw., and if so 

 the first of his suggestions is in accordance with the view of 

 Dr. Stuhlmann, as expressed in a recent paper [XXVI.], which 

 shortly stated is that Gl. morsitans is the only species capable of 

 conveying Tsetse-fly disease. From a quotation already given 

 the reader will understand that Dr. Stuhlmann bases his conclu- 

 sion upon the analogy between Tsetse-fly disease and malaria 

 and Texas fever (c/. p. 300). Elsewhere he writes [XXVI.] : 

 " The fact is that, in the case of all these blood diseases, the host 

 and intermediate host ai-e animals of perfectly definite kinds. 

 It is, moreover, improbable that the proboscis of the Tsetse 

 merely operates as an inoculating needle ; rather must we 

 assume, from analogy with malaria, that within the fly the 

 Trypanosoma passes through a special stage of development, 

 which it is true is at present unknown." In this conclusion 

 Stuhlmann is supported by Veterinary-Surgeon Schmidt, in a 

 memorandum which is quoted on p. 263. So far as I am aware, 

 the only modes of reproduction which have yet been observed in 

 any Trypanosome are either binary longitudinal fission, or the 

 breaking off from a plasmodium, formed by the fusion of a 

 number of adults, of amoeboid forms which subsequently assume 

 the well-known adult stage. Nevertheless, although nothing 

 has yet been observed in the case of Trypanosoma in any way 

 comparable to the gametocytes in that of the pai^asites of 

 malarial fevers in man, it is of course quite possible that on 

 entering the stomach of the Tsetse the parasites become sexually 

 mature, and that it is their progeny and not they themselves 

 that subsequently find their way into the blood of another 



* Somewhat similar conditions would appear to exist in Loango, 

 or at least to have existed there at the time of the German Loango 

 Expedition about thirty years ago [Cf. 65, 6Sa, 80, and Chapter II., 

 p. 40). 



