But the intense dryness modifies plant-life in another way; vegetation being scarce, all forms are eagerly sought after by animals; and an unusual number are protected by thorns, or by an intense bitterness, or by imitative adaption. One curious little plant protects itself by assuming the likeness of a hard white lichen that covers the rocks: its sharp-pointed green leaves are placed close together with their tips upwards, and on the tip of each leaf is a little white scaly sheath; the resemblance to the lichen growing on the rocks, besides which it is always found, is so great, that not till you tread on it, and your foot sinks in it, do you discover the deception. Even on the insect life the exceptional conditions of the Karoo have a marked effect. Imitative colouring is more common here than elsewhere; thus, one insect is so like the white pebbles near which it is always found, that once dropped it cannot easily be again found; another large square insect with hardly any power of flight protects itself by lying motionless on red stones, which it so exactly resembles in colour, having even the rough cleavage marks upon it, that it is impossible to detect it, though you know it to be there; hardly any insect or reptile exists without imitative colouring. To see the Karoo rightly one should saddle one's horse and ride away from some solitary farm-house. For twenty miles you may ride without seeing a living thing, nor passing even a herd of sheep or goats, or a korhaan or mierkat. At midday you off-saddle in a narrow plain between two low hills, that widen out at the further end into a wider plain, from which rise two conical, solitary, flat-topped hills; and the horizon is bounded by a purple mountain thirty miles off. You put your saddle down beside a milk bush and tie the halter round the horse's knee, that he may go and feed upon the bushes; and you seat yourself beside your saddle on the ground. The milk bush gives little shade, and the midday sun shines hot upon you. In the red sand at your feet the ants are running to and fro, carrying away the crumbs that may have fallen from your saddle-bag; and in the stillness you can hear your horse break the twigs from the bushes as he feeds; he moves further off, and you cannot hear even that. Then you notice on the red sand a little to the right, at the foot of a Karoo bush, a scaly lizard, with his head raised, and his belly palpitating on the red sand, watching you. He is a tiny fellow, three inches long. You move, and he is gone like a flash of light across the sand. By and by the ants have carried away the crumbs, and they too are gone. You sit alone with the sun beating down on you. As the plain lies to-day, so it has lain for long countless ages. Those sharp stones on the edge of the rise to your right, with their points turned to the sky, for how many centuries have they lain there, their edges as sharp and fresh to-day as though they