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common house-fly, with a sober brownish or brownish-grey coloration. The 

 tsetse flies rapidly and directly to the object it seeks. Like the mosquito it 

 is greedy and sucks voraciously. Unlike so many of the blood-sucking 

 Diptera, in which the habit is confined to the females, both sexes of Glos- 

 sina attack warm-blooded creatures. The fly always seems to choose a very 

 inaccessible portion of the body to operate on, between the shoulders in 

 man, or on the back and belly in cattle and horses, even inside the nostrils 

 in the latter, or on the forehead in dogs. 



The flies and mosquitoes which we have considered are found practically 

 all over the world, but the genus Glossia is fortunately confined to Africa. 

 Its northern limit corresponds with a line drawn from the Cambia through 

 Lake Chad to Somaliland, somewhere about the thirteenth parallel of north 

 latitude. Its southern limit is about on a level with the northern limit of 

 Zululand. Even where the tsetse is found it is not uniformily distributed, 

 but occurs in certain localities only. These form the much dreaded " fly- 

 belts," where the normal prev of the fly is undoubtedly the big game of 

 Africa. 



The tsetse fly belongs to the family Muscidae, the true flies, a very large 

 family, which also includes our house-flv, blue-bottle flv, etc. These flies, 

 unlike Anopheles and Culex, are day-flies, and begin to disappear at or about 

 sunset. The practical disappearance as the temperature drops has enabled 

 the South African traveller to traverse the fly-belts with impunity during 

 the cooler hours of the night. At nightfall the tsetse seems to retire to rest 

 amongst the shrubs and undergrowth ; but if the weather be warm, it may sit 

 up late ; and some experienced travellers refrain from entering a flv-belt until 

 the temperature has considerably fallen. 



The sickness and death of the cattle bitten by the tsetse were formerly 

 attributed to some specific poison secreted by the fly, and injected during the 

 process of biting. It is now, largely owing to the researches of Colonel 

 Bruce, known to be due to the inoculation of the beasts with a minute para- 

 sitic organism conveyed from host to host by the fly. The disease is known 

 as " nagana," and the organism that causes it is a species of Trypanosoma, 

 a flagellate protozoon or unicellular organism, which moves by means of the 

 lashing of a minute, whip-like process. It is from the big game that the 

 disease has spread. In their bodies the harmful effect of the parasites has, 

 through countless generations, become attenuated; but it leaps into full 

 activity again as soon as the Trypanosoma wins its way into the body of 

 any introduced cattle, horse, or domesticated animal. 



The report of Colonel Bruce, which has just been issued, shows that the 

 sleeping sickness which devastates Central Africa, from the west coast to the 



