DIPTEEA. 75 



beneath the skin is seen to be injected with air, as if a quantity 

 of soap bubbles were scattered over it, or a dishonest awkward 

 butcher had been trying to make it look fat. The fat is of a 

 greenish-yellow colour, and of an oily consistence. All the 

 muscles are flabby, and the heart often so soft that the fingers 

 may be made to meet through it. The lungs and liver partake 

 of the disease. The stomach and bowels are pale and empty, and 

 the gall-bladder is distended with bile. These symptoms seem 

 to indicate, what is probably the case, a poison in the blood ; the 

 germ of which enters when the proboscis is inserted to draw 

 blood. The poison- germ contained in a bulb at the root of the 

 proboscis, seems capable, although very minute in quantity, of 

 reproducing itself. The blood after death by Tsetse is very small 

 in quantity, and scarcely stains the hands in dissection. . . . 



" The mule, ass, and goat enjoy the same immunity from the 

 Tsetse as man and the game. Many large tribes on the Zambesi 

 can keep no domestic animals except the goat, in consequence of 

 the scourge existing in their country. Our children were fre- 

 quently bitten, yet suffered no harm ; and we saw around us 

 numbers of zebras, buffaloes, pigs, pallahs, and other antelopes, 

 feeding quietly in the very habitat of the Tsetse, yet as undisturbed 

 by its bite as oxen are when they first receive the fatal poison. 

 There is not so much difference in the natures of the horse and 

 zebra, the buffalo and ox, the sheep and the antelope, as to afford 

 any satisfactory explanation of the phenomenon. Is a man not 

 as much a domestic animal as a dog ? 



" The curious feature in the case, that dogs perish though fed on 

 milk, whereas the calves escape so long as they continue sucking, 

 made us imagine that the mischief might be produced by some 

 plant in the locality, and not by Tsetse ; but Major Yardon, of the 

 Madras army, settled that point by riding a horse up to a small 

 hill infested by the insect, without allowing him time to graze, 

 and though he only remained long enough to take a view of the 

 country and catch some specimens of Tsetse on the animal, in ten 

 days afterwards the horse was dead." * 



* " Missionary Travels and Researches in South Africa, by David Livingstone, 

 LL.D., D.C.L." London, John Murray, 1857, p. 81, et seq. (The extract in the 

 original of this work is from a French translation : "Explorations dans 1'Interieur 



