140 SWAEM OF TSET.SE ON ZAMBESI. 



*'In most Tsetse countries the traveller is not usually 

 beset with more than two or three at a time ; in the course 

 of the heat of the day these might produce a number of 

 bites, besides falling in with fresh flies as one advanced. 

 But they are sometimes found in much gi-eater numbers. 

 On the south side of the Zambezi, near the confluence of 

 the Kafue, while walking along the river-bank in search of 

 game, under flat-topped acacias, I heard a buzzing sound, 

 and saw a cloud of insects coming towards me. Supposing 

 them a swarm of bees, I ran off, while they followed. On 

 looking back I found it was only ' Tsetse ' ; so, arming 

 myself with a leafy branch, I kept them off and continued 

 my journey ; they accompanied me for some distance 

 however. I have never again seen them congregate in 

 this manner ; and, curiously enough, on this occasion, and 

 on this only, did I obtain two of what may be the male 

 insect ; these bear the proportion to the females of 1 : 30,* 

 judging by the numbers then caught" (p. 155). 



General description of the structure and mode of action 

 of the proboscis (pp. 155-156). 



The fatal effect of the htte of the Tsetse in the case of 

 domestic animals ascribed to ^'irritant matter" injected by 

 the fly, in order to ^'■facilitate the suching of blood." 



" The iri'itation which follows the bite in man shows 

 that some irritant matter is at the same time injected 

 (although no organ for its secretion has yet been detected), 

 the object of which is no doubt to cause a local congestion, 

 and thus facilitate the sucking of blood. The accidental 

 effects of this, which in animals among whom the 'Tsetse' 

 naturally lives produces no after result, in the domestic 

 animals before-named proves fatal" (p. 156). 



29. i866. Sir Samuel W. Baker. 



" The Albert N'yanza, Great Basin of the Nile, 

 AND Explorations of the Nile Sources " (London : 

 Macmillan & Co.) : Vol. I., p. 376. 



Tsetse-fly in Obbo (S.E. of Gondokoro, just north of 

 4:" N. lat., and between 32° and 33' E. long.).—" The 

 wet herbage disagi-eed with my baggage animals. 

 Innumerable flies appeared, including the Tsetse, and in 

 a few weeks the donkeys had no hair left, either on their 



* [C/. p. 86.] 



