at the same time attacked, yields to remedies which do not operate by the same principle, by the same mode of action on the same organs, by the same play of chemical and electrical attractions? We shall here confine ourselves to this observation, that, in the species of the genus cinchona, like antifebrile virtues do not appear to reside in the tannin (which is only accidentally mingled in them), or in the cinchonat of lime; but in a resiniform matter, soluble both by alcohol and by water, and which, it is believed, is composed of two principles, the cinchonic bitter and the cinchonic red *. Can it then be admitted, that this resiniform matter, which possesses different degrees of energy according to the combinations by which it is modified, is found in all the febrifuge substances? Those by which the sulphat of iron is precipitated of a green colour, like the real cinchona, the bark of the white willow, and the horned perisperm of the coffee tree, do not on this account indicate an indentity of chemical composition;

* In French, l'amer et le rouge cinchoniques.

The cuspare bark (cort. angustura) yields with iron a yellow precipitate; yet it is employed on the banks of the Oroonoko, and particularly at the town of St. Thomas of Angustura, as an excellent cinchona; and on the other hand, the bark of the common cherry tree, which has scarcely any febrifuge quality, yields a green precipitate like the real cinchonas. (Vauquelin; Annales de Chimie, T. 59, page 143. Reuss, in the Journal de Pharmacie, 1815, page 505. VOL. III.

D

and this indentity might exist, without our concluding thence, that the medical virtues were analogous. We see, that the different species of sugar and tannin, when they are extracted from plants not of the same family, display numerous differences: while the comparative. analysis of sugar, gum, and starch; the discovery of the radical of the prussic acid, the effects of which are so powerful on the organization; and so many other phenomena of ve getable chemistry; clearly prove, that "substances composed of a small number of identical' elements, and in the same proportion, exhibit the most heterogeneous properties," on account of that particular mode of combination, which corpuscular chemistry calls the arrangement of the particles *.

On coming out of the ravine which descends from the Impossible, we entered a thick forest traversed by a great number of small rivers

Grindel, Russisches Jahrb, der Pharm. 1808, p. 183). Notwithstanding the extreme imperfection of vegetable chemistry, the experiments already made on cinchonas sufficiently show, that to judge of the febrifuge virtues of a bark, we must not attach too much importance either to the principle that turns to green the oxides of iron, or to the tannin, or to the matter that precipitates infusions of tan.

Gay-Lussac, Exp. on Jodine, page 149, note 1, (Humb. Vers. ueber gereizte Muskelfaser, B. 1, p. 128.)

+ The Manzanares; the Cedeno, with a plantation of cacao trees, and an hydraulic wheel; the Vichoroco; the Lucas

which are easily forded.

We observed, that the

cecropia, which by the disposition of it's branches, and it's slender trunk, resembles the port of the palm tree, is covered with leaves more or less silvery, in proportion as the soil is dry or moist. We saw some plants of it, the leaf of which was on both sides entirely green*. The roots of these trees are hid under tufts of dorstenia, which flourishes only in humid and shady places. In the midst of the forest, onthe banks of the Rio Cedeno, as well as on the southern declivity of the Cocollar, we find, in their wild state, papaw trees, and orange trees with large and sweet fruit. These are probably the remains of some conucos, or Indian plantations; for in those countries the orange tree cannot be counted among the indigenous plants, any more than the banana tree, the papaw tree, maize, cassava, and so many other useful plants, with the true country of which we are unacquainted, though they have accompanied man in his migrations from the remotest times.

When a traveller newly arrived from Europe penetrates for the first time into the forests of South America, nature presents herself to him under an unexpected aspect. The objects that

perez, with a habitation that is called Pie de la Cuesta; the Rio St. Juan; &c.

Is not the cecropia concolor of Willdenouw a variety of the cecropia peltata?

surround him recall but feebly those pictures, which celebrated writers have traced on the banks of the Missisippi, in Florida, and in other temperate regions of the new world. He feels at every step, that he is not on the confines, but in the centre of the torrid zone: not in one of the West India islands, but on a vast continent, where every thing is gigantic, the mountains, the rivers, and the mass of vegetation. If he feel strongly the beauty of picturesque scenery, he can scarcely define the various emotions, which crowd upon his mind; he can scarcely distinguish what most excites his admiration, the deep silence of those solitudes, the individual beauty and contrast of forms, or that vigour and freshness of vegetable life, which characterize the climate of the tropics. might be said that the earth, overloaded with plants, does not allow them space enough to unfold themselves. The trunks of the trees are every where concealed under a thick carpet of verdure; and if we carefully transplanted the orchideæ, the pipers, and the pothos, which a single courbaril, or American fig-tree* nourishes, we should cover a vast extent of ground. By this singular assemblage, the forests, as well as the flanks of the rocks and mountains, enlarge the domains of organic nature. The same

• Ficus gigantea.

It

lianas as creep on the ground, reach the tops of the trees, and pass from one to another at the height of more than a hundred feet. Thus by a continual interlacing of parasite plants, the botanist is often led to confound the flowers, the fruits, and leaves, which belong to different species.

We walked for some hours under the shade of these arcades, that scarcely admit a glimpse of the sky; which appeared to me of an indigo blue, so much the deeper as the green of the equinoctical plants is generally of a stronger hue, with somewhat of a brownish tint. A great fern tree*, very different from the polypodium arboreum of the West Indies, rose above masses of scattered rocks. In this place we were struck for the first time with the sight of those nests in the shape of bottles, or small pockets, which are suspended to the branches of the lowest trees, and which attest the admirable industry of the orioles, that mingle their warblings with the hoarse cries of the parrots and the macaws. These last, so well known for their vivid colours, fly only in pairs, while the real parrots wander about in flocks of several hundreds. A man must have lived in those climates, particularly in the hot valleys of the Andes, to conceive how these birds sometimes drown with their voice

• Perhaps our aspidium cabucum.