Finally we will quote some general conclusions and explanations regarding the method of using our different preparations, based on observations made by competent physicians in Europe and America. [Illustration] [Illustration: SPECIMEN OF THE COCA SHRUB. (Grown in a Hot-house by Mr. Mariani showing general frail condition of the leaf.)] [Illustration] CHAPTER I. ERYTHROXYLON COCA, ITS BOTANICAL CHARACTER. Coca is indigenous to South America. The different botanists disagree as to which exact family it should be assigned. Linnæus, De Candolle, Payer, Raymundi of Lima, Huntk, and others, place it in the family of the _Erythroxyleæ_, of which there exists but one genus, the _Erythroxylon_, while Jussien adopts another classification and places it in the family of the _Malpighiaceæ_ (_genus Sethia_). Lamarck, on the contrary, believes that this plant should be classed among the family of Nerprem (Rhamneæ). _Erythroxylon Coca_ is a shrub which reaches a height of from six to nine feet and the stem is of about the thickness of a finger. In our climate it cannot thrive except in a hot-house, and there its height does not exceed one metre. The root, rather thick, shows multiple and uniform divisions; its trunk is covered with a ridged bark, rugged, nearly always glabrous, and of a whitish color. Its boughs and branches, rather numerous, are alternant, sometimes covered with thorns when the plant is cultivated in a soil which is not well adapted to it. The leaves, which fall spontaneously at the end of each season, are alternate, petiolate, with double intra-accillary stipules at the base. In shape they are elliptical-lanceolate, their size varying according to the nature of the plant or of the soil in which it grows. The leaf of Coca gathered in Peru, of which we give two figures of the natural size, is generally larger and thicker than the leaf of the Bolivian Coca. It is also richer in the alkaloid, consequently much more bitter. The Coca leaf from Bolivia, smaller than the Peruvian leaf, is as much esteemed as the latter, although it contains less of the alkaloid. It possesses so exquisite and so soft an aroma, indeed, that the _coqueros_ seek it in preference to any other. [Illustration: LEAVES OF PERUVIAN COCA, NATURAL SIZE A. Upper surface of the leaf. B. Lower surface of the leaf, showing the longitudinal projections of the two sides of the midrib.] The Coca leaves of Brazil and Colombia are much smaller than those of Peru and Bolivia. Their color is much paler. Containing but traces of the alkaloid they are not bitter, and possess a pleasant, but very volatile aroma. One of the most important characteristics of the Coca leaf is the disposition of its nervures; parallel with the midrib two longitudinal projections are to be seen, which, starting from the base of the leaf, extend in a gentle curve to its point. [Illustration: LEAVES OF BOLIVIAN COCA, NATURAL SIZE. (Lower surface.)]