Chap. IV. THE TSETSE POISON. 57 



The poison does not seem to be injec ted by a sting, or by 

 ova placed beneath the skin, for, when the insect is allowed 

 to feed freely on the hand, it inserts the middle prong of three 

 portions, into which the proboscis divides, somewhat deeply 

 into the true skin. It then draws the prong out a little way, 

 and it assumes a crimson colour as the mandibles come into 

 brisk operation. The previously shrunken belly swells out, 

 and, if left undisturbed, the fly quietly departs when it is full. 

 A slight itching irritation follows the bite. In the ox the 

 immediate effects are no greater than in man ; but a few days 

 afterwards the eye and nose begin to run, the coat stares, 

 a swelling appears under the jaw, and sometimes at the navel ; 

 and, though the poor creature continues to graze, emaciation 

 commences, accompanied with a peculiar flaccidity of the 

 muscles. This proceeds unchecked until, perhaps months 

 afterwards, purging comes on, and the victim dies in a state of 

 extreme exhaustion. The animals which are in good condition 

 often perish soon after the bite is inflicted with staggering 

 and blindness, as if the brain were affected. Sudden changes 

 of temperature produced by falls of rain seem to hasten the 

 progress of the complaint ; but in general the wasting goes on 

 for months. 



When the carcase is opened, the cellular tissue beneath the 

 skin is found injected with air, as if a quantity of soap-bubbles 

 were scattered over it. The blood is small in quantity, and 

 scarcely stains the hands in dissection. The fat is of a 

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

 muscles are flabby, and the heart is 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 poison in the blood; the 

 germ of which enters when the proboscis is inserted. 



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 frequently 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 



