The Apocynaceae in Materia Medica, cont'd.
Allamanda Cathartica L., all the Allamanda are energetic evacuants. The A. cathartica is a native of Guiana, where the leaves are commonly employed as a purgative. The A. Schottii Pohl. of Brazil has similar properties.
Echites suberecta Jacq. [Pentalinon luteum]—A plant of the West Indies, especially Jamaica, and introduced into the Bahamas. Bowrey has analyzed the plant and isolated Urechitine a very toxic, crystalline glucoside; Urechitoxine, likewise a toxic glucoside, acrid and crystalline or amorphous. These two bodies are extremely active cardiac poisons and their therapeutic application does not appear permissible. The plant is stated to be used for criminal poisonings by the negroes.
The leaves of the Echites biflora Jacq. [Tabernaemontana peschiera] of Central America and the Antilles is stated to be purgative and applied topically to scrofulous ulcers. The leaves of Echites longiflora Desf [Mandevilla longiflora], of the Argentine Republic are strongly purgative and in infusion are employed against haemorrhoids and used also in cataplasm.
Aspidosperma quebracho Schlecht.—The leaves of this tree are verticillate in threes, deep green, lanceolate, subsessile, coriaceous, smooth and terminated as in many of the species of this genus by a sharp point. They are said to contain 27.5 per cent. of tannin and to be employed in the industries.
Geissospermum Vellosii Fr. Allem. [Geissospermum laeve]—The leaves of this plant are extremely bitter. They contain Pereirine, but in less quantity than the bark and seem to be but little used. They are lanceolate, attenuated at the base and short petiolate and prolonged into a long point at the summit; borders undulate, entire; the surface smooth and shining; greenish or brownish, brighter but less glossy beneath.
Caoutchoucs and Guttas.
The products formed by coagulation of the latex of the apocynaceae nearly all caoutchoucs, but some are true guttas. [Caoutchouc and Gutta Percha are two substances very similar, differing only in a few points. At the ordinary temperature Caoutchouc is elastic, Gutta is solid. On warming, the caoutchouc becomes adhesive, but remains elastic; the gutta becomes malleable and plastic, but not elastic. With prolonged action of heat and air caoutchouc is transformed to a sort of pitch, gutta becomes brittle and resinous. Ether readily dissolves caoutchouc, and is a poor solvent for gutta; with oil of turpentine the solvent action is reversed. Sulphur combines readily with caoutchouc and but poorly with gutta.] The number of apocynaceae containing caoutchouc is considerable, but only in comparatively few are the products utilized or of commercial importance. They are, for the most part, obtained from the stems of climbing plants. The solidification is sometimes allowed to take place naturally, but generally by concentrating by exposure to the sun or by fire. Rapid coagulation has the advantage of preventing from the beginning injurious fermentation, which develops disagreeable odors in the caoutchouc and alterations, and yields a product harder, more dense and containing less water. Coagulation can also be produced by chemical means, as by acids (sulphuric, nitric, tartaric or lemon juice, etc.) or by sodium chloride, sea-water, alum, etc. Coagulation by heat is usually preferred, and during the operation it is necessary to strongly compress the product.
For the most part the American caoutchoucs are excellent for industrial purposes; their resistance, their toughness and their considerable hardness is much appreciated, and equatorial America furnishes alone the best caoutchouc for all the rest of the world.
All the caoutchoucs of Mexico, Central America, Columbia Guiana, Ecuador, and likewise a large part of that from Brazil, are exclusively furnished by Euphorbiceae (Hevea, Siphonia, etc.) or by Urticaceae (Castilloa, Cecropia, etc.)
The Hancornia specicosa. Gomez is, with one or two closely allied species, the principal caoutchouc yielding Apocynaceae of America. It yields the varieties known as Pernambuco caoutchouc, Maranham Caoutchouc, and Bahia Caoutchouc. The first appears in plates varying in thickness from 0.5 to 7 c.m., of a rose color and an efflorescence of alum on the surface. Its quality is very inferior to that of Para or of the Malay caoutchoucs. The Maranham Caoutchouc is deeper in color, like wine-lees, with brown marbling. The surface is smooth, non- efflorescent, harder and less porous, and contains less water. It is probably coagulated by sulphuric acid. The Bahia Caoutchouc is said to be produced from the variety minor of Hancornia. It is rare and of but little value, possessing none of the excellent qualities. It contains much water and foreign substance and a certain quantity of non-solidified latex. It is in masses or large plates, rose-colored, and is probably prepared by spontaneous coagulation.
The caoutchoucs of Africa are furnished almost exclusively by two genera of Apocynaceae, the Vahea and the Landolfia, which many botanists consider under one genus. A few Ficus and some Asclepiadeae may produce a little of the gum elastic, but generally this is not appreciable and the true caoutchoucs of Africa are furnished by these Apocynaceae. The Vahea tomentosa Leprieur [Landolphia heudelotii], furnishes a large proportion of the Senegal caoutchouc. The V. Senegalensis A. DC. [Saba senegalensis] likewise is said to yield a large quantity. These lianes are of small diameter and greatly entangled and the most usual method of collection is to cut them and collect the juice, which flows very rapidly. Each plant yields 3 to 4 kilos of caoutchouc. The solidification is accomplished by water containing acids or salt in solution. In the interior of the continent, the coagulation seems to be accomplished by sun heat and the product made into balls with ashes. This caoutchouc enters commerce generally in plates weighing 130 to 150 gm. blackish externally, and grayish within and containing a large proportion of water, or in balls, more highly esteemed and freer from impurities, varying from 8 to 60 gm. and united in groups of from 15 to 20, and these are of a rose color.
The Landolfia Heudelotii A, DC. and the L. Owariensis Pal. de Beauv., are important as caoutchouc producing plants. They inhabit the western side of tropical Africa and the latter plant is said especially to produce the caoutchouc from Sierra-Leone, which appears in balls, mostly of a slate color internally. The Landolfia florida Benth [Saba comorensis], occupies an altitude of 2,500 feet and is found also in Mozambique and is the source of a large amount of caoutchouc. The caoutchouc of Gaboon is undoubtedly derived from the two last-named plants. It appears in masses, white upon cutting, quite consistent, containing much water and but little foreign matters. It is readily purified and then remains firm and resistant. It is estimated that from the French colonies there is annually exported 400 tons. The Landolfia Kirkii occupies the oriental regions of Africa, especially Zanzibar and Mozambique, being the "Matire" or "Mtiri" of the natives. It is the most important species of this region and its latex solidifies spontaneously so readily that artificial coagulation is unnecessary. The exportation of this product in 1879 was valued at 1,125,000 francs. The L. Petersiana [Ancylobotrys petersiana] inhabiting the same region is characterized by an extremely fluid latex, the coagulation being secured by acids or by fire.
The caoutchoucs of Madagascar are furnished by Vahea madagascariensis Boj. [Landolphia gummifera] (V. gummifera Lamk, and V. Comorensis Boj. [Saba comorensis] ; and are coagulated by acids, lemon juice being mostly used.
In India several species of Willughbeia are said to yield caoutchoucs. The Alstonia scholaris, the source of Dita bark, is said to yield a gutta of poor quality. In the region of Indo-China a number of species yield caoutchoucs generally of little value.
The only Apocynaceae of Oceanica important in this respect is the Urceola elastica Roxb, This plant and the Asclepiad, Calotropis gigantea furnish nearly all of the caoutchouc of Borneo and is likewise known as white Assam caoutchouc. The Urceola is a tree about 10 c.m. in diameter and the latex is extracted by making a V- shaped incision as far as the cambium.