Du Chaillu, whose account of the driver-ants, or bashikonays, I have already quoted, describes their manner of bridging streams in a slightly different way, which, if correct, makes it still more remarkable. He says: “When, on their line of march, they require to cross a narrow stream, they throw themselves across, and form a tunnel—a living tunnel—connecting two trees or high bushes on opposite sides of the little stream, whenever they can find such, to facilitate the operation. This is done with great speed, and is effected by a great number of ants, each of which clings with its fore claws to its next neighbour’s body or hind claws. Thus they form a high, safe tubular bridge, _through_ which the whole vast regiment marches in regular order. If disturbed, or if the arch is broken by the violence of some animal, they instantly attack the offender with the greatest animosity.” This presents the matter in a still more interesting light, and as it is the account of a man who professes to have seen what he describes, it should rank, perhaps, before the other, which, though I have taken it from a trustworthy source, was not there given as a first-hand account. Both versions, however, may be correct. If streams are not sufficient to daunt the driver-ant, neither are floods. When these occur, numbers of them rush together and cling to one another, forming a ball-shaped mass, that, being lighter than the water, floats upon it, till such time as the flood has retired. The size of these balls is, for the most part, that of an orange, but they may be either larger or smaller—tangerine orange-balls in the latter case. The natives say that the larger and stronger ants form the outer circumference of the globe, whilst the weakly ones—or, as they express it, the women and children—are contained and guarded in the centre. I have never seen the real driver-ants, not having been in any really tropical country. In South Africa, however, I have often seen the armies, or, as the Kaffirs call them, _impis_, of a black, stinging ant, that seems to take their place. When these insects are disturbed in their march, the whole column makes a hissing noise, which can be very distinctly heard. How the sound is produced I do not know, but it is more like a hiss than anything else, and is accompanied, if I remember rightly, with a strong smell of formic acid. Though these black ants are fierce and bold, so that the Kaffirs admire them, call them warriors, and compare them with themselves, their marches are not attended with the striking sights which belong to those of the drivers, nor have they the wonderful habits or instincts of the latter. They are less than half their size, moreover, and their chief weapon being a sting, the mandibles are not extraordinarily developed. I never myself happened to be stung by one, but have heard others complain bitterly.