Against these heavy and voracious foes, a fence would be of little avail, as the hippopotamus could force its way through the barrier without injury, thanks to its thick hide. The owner of the field therefore encloses it within a tolerably deep ditch, and furthermore defends the ditch by pointed stakes: so that, if a hippopotamus did happen to fall into the trench, it would never come out again alive. A similar defence is sometimes made against the inroads of the elephants. Those animals do not often take it into their heads to attack a garden in the vicinity of human habitations; but when they do so, it is hardly possible to stop them, except by such an obstacle as a ditch. Even the ordinary protection of a fence and the vicinity of human habitations is worthless, when a number of elephants choose to make an inroad upon some field; and, unless the whole population turns out of the kraal and uses all means at their command, the animals will carry out their plans. The elephant always chooses the night for his marauding expeditions, so that the defenders of the crops have double disadvantages to contend against. One weapon which they use against the elephant is a very singular one. They have an idea that the animal is terrified at the shrill cry of an infant, and as soon as elephants approach a kraal, all the children are whipped, in hopes that the elephants may be dismayed at the universal clamor, and leave the spot. Antelopes of various kinds are exceedingly fond of the young corn blades, and, if the field be without a fence, are sure to come in numbers, and nibble every green shoot down to the very ground. Near the bush the buffalo is scarcely less injurious, and more dangerous to meddle with; and even the porcupine is capable of working much damage. The wild swine, however, are perhaps the worst, because the most constant invaders, of the garden. Even a fence is useless against them, unless it be perfect throughout its length, for the pigs can force themselves through a wonderfully small aperture, owing to their wedge-shaped head, while their thick and tough skins enable them to push their way through thorns and spikes without suffering any damage.