OLFACTOEY TOWERS OF TSETSE. 223 



the Tsetse accidentally meets with domestic animals, it 

 pursues them with peculiar pertinacity ; the animal has 

 an instinctive sense of the danger that threatens it : it 

 jumps, shies, and after the first bite, the noise alone 

 of the fly literally deprives it of its senses ; it loses 

 its head and bolts, hoping in this way to outstrip the 

 murderous insect buzzing round it. The venomous fly 

 comes to its prey from a long distance, whether it is 

 that its sight is keen or its sense of smell exceptionally 

 acute ; I would incline rather to the latter hypothesis, 

 since I have noticed that the fly always comes up wind, 

 and generally bites by prefei-ence on the leeward side. 

 The Tsetse keeps on the under, not on the upper side of 

 leaves, as one never sees it, and it prefers shade to sun. 

 It especially dislikes the odour of excrement ; as soon as 

 an antelope is killed, for instance, in order to get rid of 

 the Tsetse which literally cover game and hunters, it is 

 only necessary to open the animal's belly and evacuate 

 the entrails ; the insect at once ceases to torment you '' 

 (pp. 29-31). 



Symptoms of Tsetse-fly disease in cattle (pp. 31-32). 

 The interval that elapses before death depends upon 

 the number of bites (p. 32). 



The Tsetse follows the big game, of the existence of 

 which in a district its presence is a proof. " It is parti- 

 cularly partial to buffaloes and the large antelopes ; that 

 is why one finds districts containing small game devoid of 

 Tsetse." The fly will disappear simultaneously with the 

 destruction of the big game (pp. 32-33). 



" I have still to speak of the sensations experienced by 

 a human being after being bitten by the poisonous insect. 

 The itching feeling changes in a few seconds to a painful 

 pruritus which lasts about a quarter of an hour ; the bitten 

 part reddens, swells slightly, and continues to be uncom- 

 fortable for a short tiaie (pendant un moment). A large 

 number of bites may undeniably have a disturbing effect 

 upon the organism; above all, they have the effect of 

 exciting one excessively, and a feeling of rage is added to 

 the suffering. The parts affected by the fly in the case of 

 man are generally those that are uncovered : hands, arms, 

 neck, cheeks, and legs, always on the under side as much 

 as possible " (p. 33). 



