Referring once again to the fact of the water in the main streams backing up the tributaries, so very slight is the inclination of the western plains, and so small the fall of its streams, that swelling of the Orinoco, or wind pressure, will force the water to flow up the tributaries, whirlpools forming where the opposing currents meet. Humboldt states that under these conditions many natives firmly believed that in travelling up these streams in their canoes they were really descending for a considerable distance. Apart from the change of season from wet to dry, the great factor in the climate of the llanos is the trade wind, which blows across from the east to the west. The sandy ground, thinly covered with grass, becomes very hot in the daytime and heats the air near it. In the east the trade wind, arriving fresh from the sea, lessens this effect, and makes the air pleasant, but as it sweeps across the hundreds of miles of burning soil it becomes itself heated, and as it gets farther west adds to the discomfort, instead of correcting it. In fact, the western llanos are very hot, and although there is a twelve-hours night in which to cool, there is so much heat to be radiated off from the earth that when dawn, the coolest moment, arrives very little diminution of temperature has been attained, and the heating process begins again. The llanos, then, are neither prairie nor desert, but hold rather an intermediate position, varying towards one or the other according to the season. Various grasses suitable for feeding live stock grow here, and there are some trees, notably varieties of mimosas, one with sensitive leaves (_dormideras_) very good for cattle. There are also palms, notably the Corypa palms, or _palmas de Cobija_, with hard wood, which are good for building huts, their leaves being used for the roof, and the Moriche palm (_Mauritia flexuosa_), which, as already noticed, furnishes nearly all the necessities of life to the Guarauno Indians of the Delta. The llanos originally contained deer, the river swine or capybara (_chiguire_), and the jaguar, also wild ducks and geese. In 1548 Cristobal Rodriguez started sending cattle into the plains to multiply. In Humboldt’s time the live stock were estimated at 1,200,000 oxen, 180,000 horses, and 90,000 mules. Wars and diseases have at different times interrupted their increase. Horses, asses, and mules were abundant and cheap up to 1843, when a pestilence destroyed nearly all the wild ones, the loss being estimated at between six and seven million beasts. The cattle are believed to have decreased between the years 1863-73 from 5,000,000 to 1,400,000, but by 1888 were estimated at 8,500,000 again. Cattle-breeding should be a great and important industry for Venezuela, and it is to be hoped that it will be put on a better footing before long. An up-to-date factory for killing and chilling meat has been established at Puerto Cabello, and the first shipment took place in 1910.