The best soil is that made by the decomposition of volcanic rock, so that it is a common sight to find areas strewn with large boulders turned into a cocoa plantation of great fertility; but the best trees of all lie along the _vegas_ which intersect the hills, where the soil is deep, and the stream winding among the trees supplies natural irrigation. The tree also grows well in loams and the richer marls, but will not thrive on clay and other heavy soils. The cacao is one of the tenderest of tropical growths, and will not flourish in any exposed position, for which reason large shade belts are left along exposed ridges and other parts of a hill estate, thus greatly reducing the total area under cultivation, in comparison with an estate of equal extent on the level plains, where no shade belts are necessary. The beans are planted either "at stake,"--when three beans are put in round each stake, the one thriving best after the first year being left to mature,--or "from nursery," whence, after a few months' growth in bamboo or palm-leaf baskets, they are transplanted into the clearing. The preparation of the land is the first and greatest expense; trees have to be felled, and bush cut down and spread over the land, so that the sun can quickly render it combustible. When all is clear, the cacao is put in among a "catch crop" of vegetables (the cassava, tania, pigeon-pea, and others), and frequently bananas, though, as taking more nutriment from the soil, they are sometimes objected to. But the seedling cacao needs a shade, and as it is some years before it comes into bearing, it is usual to plant the "catch crop" for the sake of a small return on the land, as well as to meet this need. In Trinidad, at the same time that the cacao[10] is planted at about twelve feet centres, large forest trees are also planted at from fifty to sixty feet centres, to provide permanent shade. The tree most used for this purpose is the _Bois Immortelle_ (_Erythrina umbrosa_); but others are also employed, and experiments are now being made on some estates to grow rubber as a shade tree. In recent clearings in Samoa, trees are left standing at intervals to serve this end. [Illustration--Black and White Plate: Samoa: Cacao in its fourth Year.] In Grenada, British West Indies, and some other districts, shade is entirely dispensed with, and the trees are planted at about eight feet centres, thus forming a denser foliage. By this means at least 500 trees will be raised on an acre, against less than 300 in Trinidad, the result showing almost invariably a larger output from the Grenada estates. This practice is better suited to steep hillside plantations than to those in open valleys or on the plains.