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fine oxen by its bite. We watched the animals carefully, and believe that not a score of flies were
ever upon them.
" A most remarkable feature in the bite of the Tse-tse is its perfect harmlessness in man and
wild animals, and even calves so long as they continue to suck the cows. We never experienced
the slightest injury from them ourselves, personally, although we lived two months in their
habitat, which was in this case as sharply defined as in many others, for the south bank of the
Chobe was infested by them, and the northern bank, where our cattle were placed, only fifty yards
distant, contained not a single specimen. This was the more remarkable, as we often saw natives
carrying over raw meat to the opposite bank with many Tse-tse settled upon it.
"The poison does not seem to be injected by a sting, or by ova placed beneath the skin, for,
when one is allowed to feed freely on the hand, it is seen to insert the middle prong of three
portions, into which the proboscis divides, somewhat deeply into the true skin ; it then draws it
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 loft undisturbed, the fly quietly departs when it
is full. A light itching irritation follows, but not more than in the bite of a mosquito. In
the ox this same bite produces no more immediate effects than in man. It does not startle him as
the gad-fly does; but a few days afterwards the following symptoms supervene : the eye and
nose begin to run, the coat stares as if the animal were cold, a swelling appears under the jaw,
and sometimes at the navel ; and, though the animal continues to graze, emaciation commences,
accompanied with a peculiar flaccidity of the muscles, and this proceeds unchecked until, perhaps
months afterwards, purging comes on, and the animal, no longer able to graze, perishes in a
state of extreme exhaustion. Those which are in good condition often perish soon after the bite
is inflicted with staggering and blindness, as if the brain were affected by it. Sudden changes
of temperature produced by falls of rain seem to hasten the progress of the complaint ; but in
general the emaciation goes on uninterruptedly for months, and, do what we will, the poor ani-
mals perish miserably.
" 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 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, for the blood after death by Tse-tse is very small in quantity, and scarcely
stains the hands in dissection. I shall have by and by to mention another insect, which by the
same operation produces in the human subject both vomiting and purging.
" The mule, ass and goat enjoy the same immunity from the Tse-tse 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 the Tse-tse, 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 buffaloe and ox, the sheep and 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 Tse-tse ; 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 Tse-tse on the animal, in ten days afterwards the horse was dead.
" The well-known disgust which the Tse-tse shows to animal excreta. as exhibited when a
village is placed in its habitat, has been observed and turned to account by some of the doctors.
They mix droppings of animals, human milk, and some medicines together, and smear the animals
that are about to pass through a Tse-tse district, but this, though it proves a preventive at the
time, is not permanent. There is no cure yet known for the disease. A careless herdsman,
allowing a large number of cattle to wander into a Tse-tse district, loses all except the calves ; and
Sebituane once lost nearly the entire cattle of his tribe—very many thousands—by unwittingly
coming under its influence. Inoculation does not insure immunity, as animals which have been
slightly bitten in one year may perish by a greater number of bites in the next ; but it is probable
that with the increase of guns, the game will perish, as has happened in the South, and the
Tse-tse, deprived of food, may become extinct simultaneously with the larger animals."