[60] The leaves of this shrub (_Erythroxylon coca_) contain a stimulant substance that in its effects is much like the active principle of coffee. They are much used by the native laborers to ward off the feeling of lassitude that comes with severe labor in a tropical climate. A native porter will carry a load of one hundred pounds a distance of sixty miles with no food or rest, but merely chewing a few coca-leaves. The plant yields the substance _cocaine_, now in demand all over the world as an anaesthetic in eye and throat surgery. [61] More than a score of species of the tree from which this bark is obtained grow in the higher eastern slopes of the Andes, but a very large part is obtained from the tree, _Cinchona calisaya_. The medicinal substance, quinine, is extracted from the bark, and in the past half-century it has become the specific for malarial fevers. So great is the demand for it, that the cinchona-tree is now cultivated in India, Java, and Mexico. [62] Only a very small proportion of the Panama hats in the market are genuine. Many of the imitations, selling at retail for ten dollars or more, are serviceable hats; most of them, however, have but little worth. [63] Nitre, or "nitrate," is a native nitrate of potash, or nitrate of soda. The latter, commonly called cubic nitre or Chile saltpetre, is the kind occurring in Chile. Inasmuch as it is very soluble, a plentiful rainfall would soon leach it from the ground and carry it to the sea. The nitrate is thought to be of vegetable origin. [64] The pod of a shrub (_Caesalpina coriaria_); it contains a considerable proportion of tannin and is used for tanning leather. [65] The pericarp or pod contains about twenty-four prismatic-shaped nuts. [66] The cattle for Cuba and Brazil must be shipped in open pens in crossing the tropics. With the exports for Europe the case is different. If it is summer at the one port it is winter at the other, but it is always summer in the tropics, and cattle-ships fit for one zone are not fit for the other--hence the great difficulties in shipment of live animals to Europe. [67] For this reason Great Britain is practically a free-trade country. A protective tariff on imported food-stuffs and materials to be manufactured would hurt rather than protect British industries. [68] This is equivalent to the imposition of a tax on all the sugar consumed at home. [69] Most of the lithographic stone is obtained at Solnhofen. [70] This is a little greater than the average ton-mile rate on the New York Central Railroad between New York and Chicago. [71] The name Zuider, or Zuyder, means "south"; it was so named to distinguish it from the North Sea.