DIPTERA. 73 
“When opened, the cellular tissue on the surface of the body 
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 ae 
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 P 
“‘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 Vardon, 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, e¢ seg. (The extract in the 
