The quebracho tree usually stands out by itself and is easily discernible at a distance, both from the character of its bark and the peculiar formation of its branches. Four or five trees to the acre is about the average yield. The tree is tall, two or three feet in diameter, and is crowned by a rather thin, oval mass of branches and leaves. The leaves are oval, smooth and shiny, and it is only partially deciduous. It lives to a great age, but also grows quite rapidly, so that it can be cultivated in the future as necessity demands. Formerly this tree was sought only by the railroads for their sleepers. About fifteen years ago it was found to be full of tannin, and, as oak bark was becoming scarce, this demand was rapidly developed and now forms the principal use for quebracho. Not only the bark yields tannin, but the sap and wood as well. The bark contains about eight per cent. of tannin, the sap three or four per cent., and the heart of the tree will yield as high as twenty-five per cent. of this essence so necessary to the tanner. It is a difficult and expensive product to market because of the remoteness of the forests and scattered character of the trees. In many places narrow gauged railroads and spurs have been run out through these trackless wastes in order to bring the logs to the mills or rivers. Otherwise it would be slow work, for during a large part of the year the roads are almost impassable and oxen suffer much from the climate and insects. These light railways have been found to be by far the most economical means of getting the logs to market. One company owns four million acres of the Chaco, and is prepared to cut logs into sleepers, make fence posts, or prepare it into tannin extract, whichever offers the most profit. There is a big and constantly increasing demand for all. The increase in construction of the Argentine railways makes a demand for sleepers, and failure of other sources of supply gives an ever widening market for the tannin extract.