The hippopotamus spends most of his time in the water, but goes on land at night, especially in those districts where the rivers do not afford much food. Stealing carefully along a quiet river the traveller may often take him by surprise, and see two small jets of water rise from his nostrils when he comes up to breathe, snorting and puffing noisily. Then he dives again, and can remain under water three or four minutes. When he lies near the surface only six small knobs are seen above the water, the ears, eyes, and nostrils. If he is not quite sure of the neighbourhood, he thrusts only his nostrils above water and breathes as noiselessly as possible. Hippopotami often lie splashing in shallow water, or climb up on to the bank to sun themselves and have a quiet lazy time. Very frequently they are heard to make a grunting noise of satisfaction. When evening comes they seek the deeper parts of the river, where they swim up and down, chase one another, and roll about in the water with great nimbleness and activity. They swim with great speed, throwing themselves forward in jerks, and filling the air with their gurgling bellowing cry; yet if they like they can swim so quietly that not the least ripple is heard. A wounded hippopotamus stirs up the water so that a small canoe may capsize in the swell from his forequarters. When several old males are bellowing together, the din is heard for miles through the forest and rolls like thunder over the water. No other animal can make such a noise. Even the lion stops to listen. On the Upper Nile, above Khartum, where the most luxuriant vegetation struggles for room on the banks, and the river often loses itself in lakes and swamps, the hippopotamus, like the crocodile, seldom goes ashore. Here he lives under lotus plants and papyrus leaves, soft reeds and all the other juicy vegetation that thrives in water-logged ground. He dives and rummages for a couple of minutes, stirring up the water far around. When he has his huge mouth full of stems and leaves, he comes up to the surface again, and the water streams in cataracts off his rounded body. [Illustration: PLATE XXIX. A HIPPOPOTAMUS.] In districts where he goes on land to graze, he often works great damage among the corn and green crops, and may even attack the villagers. And he is not always to be trifled with if a canoe disturbs his repose. The most dangerous is a mother when her young ones are small. She carries them on her back as she swims and dives, sometimes to the bottom of the river. A gun must be heavily loaded if the shot is to have any effect on such a monster, and penetrate such a cuirass of hide. If the animal puffs and dives, he is lost to the hunter; but if he raises himself high out of the water and then falls again with a heavy thud, the wound is mortal and the hippopotamus sinks to the bottom. After an hour or two the body rises to the surface again.