The drug consists of a ponderous, woody, tortuous stem and root, occurring in pieces from a few inches to a foot or more in length, and from 1 to 4 inches in thickness, coated with a thin, hard, dark brown bark. The pieces are cylindrical, four-sided, or more or less flattened—sometimes even to the extent of becoming ribbon-like. In transverse section, their structure appears very remarkable. Supposing the piece to be stem, a well-defined pith will be found to occupy the centre of the first-formed wood, which is a column about ¼ of an inch in diameter. This is succeeded by 10 to 15 or more concentric or oftener eccentric zones, ⅒ to ²/₁₀ of an inch wide, each separated from its neighbour by a layer of parenchyme, the outermost being coated with a true bark. In pieces of true root, the pith is reduced to a mere point.
Sometimes the development of the zones has been so irregular that they have formed themselves entirely on one side of the primitive column, the other being coated with bark. The zones, including the layer, around the pith (if pith is present), are crossed by numerous small medullary rays. These do not run from the centre to the circumference, but traverse only their respective zones, on the outside of which they are arched together.
The drug, when of good quality, has its wood firm, compact, and of a dusky yellowish-brown hue, and a well-marked bitter taste. It exhibits under the knife nothing of the close waxy texture seen in the root of Chondodendron, but cuts as a tough, fibrous wood. Its decoction is not tinged blue by iodine. It was in this drug that Wiggers in 1839 discovered pelosine.
The drug just described, which is by no means devoid of medicinal power, has of late years been almost entirely supplanted in the market by another sort consisting exclusively of stems which are devoid of bitterness and appear to be wholly inert. They are in the form of sticks or truncheons, mostly cylindrical. Cut traversely, they display the same structure as the sort last described, with a well-defined pith. The wood is light in weight, of a dull tint, and disposed to split. The bark, which consists of two layers, is easily detached.
3. Stems of Chondodendron tomentosum R. et P.—These have been recently imported from Brazil, and sold as Pareira Brava.[131] The drug consists of truncheons about 1½ feet in length, of a rather rough and knotty stem, from 1 to 4 inches thick.[132] The larger pieces, which are sometimes hollow with age, display, when cut traversely, a small number (5-9) nearly concentric woody zones. The youngest pieces have the bark dotted over with small dark warts.
The wood is inodorous, but has a bitterish taste like the root, of which it is probably an efficient representative. Some pieces have portions of root springing from them, and detached roots occur here and there among the bits of stem. The structure and development of the latter has been elaborately examined and figured by Moss,[133] and also by Lanessan,[134] in the French translation of our book.
4. White Pareira Brava—Stems and roots of Abuta rufescens Aublet.—Mr. J. Correa de Méllo of Campinas has been good enough to send to one of us (H.) a specimen of the root and leaves[135] of this plant, marked Parreira Brava grande. The former we have identified with a drug received from Rio de Janeiro as Abutua Unha de Vaca, i.e. Cowhoof Abutua, and also with a similar drug found in the London market. Aublet[136] states that the root of Abuta rufescens was, in the time of his visit to French Guiana, shipped from that colony to Europe as Pareira Brava Blanc (White Pareira Brava).
This name is well applicable to the drug before us, which consists of short pieces of a root, ½ an inch to 3 inches thick, covered with a rough blackish bark, and also of bits of stem having a pale, striated, corky bark. Cut transversely, the root displays a series of concentric zones of white amylaceous cellular tissue, each beautifully marked with narrow wedge-shaped medullary rays of dark, porous tissue. The wood of the stem is harder than that of the root, the medullary rays are closer together and broader, and there is a distinct pith.
The wood, neither of root nor stem, has any taste or smell. A decoction of the root is turned bright blue by iodine.
5. Yellow Pareira Brava—This drug, of which a quantity was in the hands of a London drug-broker in 1873, is, we presume, the Pareira Brava jaune of Aublet—the bitter tasting stem of his “Abuta amara folio levi cordiformi ligno flavescente,”—a plant of Guiana unknown to recent botanists. That which we have seen consists of portions of a hard woody stem, from 1 to 5 or 6 inches in diameter, covered with a whitish bark. Internally it is marked by numerous regular concentric zones, is of a bright yellow colour and of a bitter taste. It contains berberine. The same drug, apparently, was exhibited in the Paris exposition of 1878 as “Liane amère” from French Guiana.