The _C. nitida_ is a lofty tree growing in the higher regions of Huanuco, and is known by the natives as _quina cana legitima_ (genuine grey bark). It grows at a greater height than the former species, and yields 2.2 per cent. of chinchonine. The _C. Peruviana_, so named by Mr. Howard, is the _Cascarilla de pata de gallinazo_ of the natives. It grows in the forests at a lower elevation than _C. nitida_, and yields 3 per cent. of chinchonine and chinchonidine, consequently indicating a considerable amount of febrifugal power. Quinine has also been found in samples of grey bark.[72] The name of _grey_ bark refers to the striking effect of the overspreading thallus of various _Graphideæ_, forming groups, and indicating that the tree has grown in an open situation, exposed to rain and sunshine. A large supply of all the best kinds of grey bark is now growing in India.[73] V.--THE CALISAYA REGION IN BOLIVIA AND SOUTHERN PERU. The chinchona region of Bolivia and Southern Peru, although one of the most important, was the last to contribute supplies of bark to the European markets. The trees first became known through the investigations of the German botanist Thaddæus Haenke, and a Spanish naval officer named Rubin de Celis, who drew the attention of the inhabitants to the valuable forests on the eastern slopes of the Bolivian Andes in 1776, though the unfortunate French naturalist Joseph de Jussieu had previously explored some portions of those forests.[74] But it was not until 1820, when quinine was first discovered as the febrifugal principle of bark, that the _Chinchona Calisaya_[75] was recognised as containing more of that alkaloid than any other species. After 1820 the demand for _calisaya_ bark increased enormously; great numbers of _cascarilleros_, or bark-collectors, entered the forests, and in a short time scarcely a tree remained in the vicinity of the inhabited places; and the bark was exported in such quantities that the price fell very much.[76] It was not, however, until 1830 that the Bolivian Government interfered in the bark trade. It was then considered necessary by General Santa Cruz's administration to check the drain of this precious source of wealth by limiting the quantity of bark to be cut or exported; and in November, 1834, the Bolivian Congress decreed a law on the subject, which, however, never took effect. Finally, the cutting was prohibited for five years, but before the expiration of that period the decree was abrogated, and an export duty of twelve dollars to twenty dollars the quintal, or cwt., was imposed.