Thapsia. Thapsia garganica.
Thapsia. T. garganica L. Thapsie, Faux Fenouil, Fr.—An umbelliferous plant, growing in Southeastern Europe, and well known to the ancients, named from the isle of Thapsos, where it was obtained. Theophrastus speaks of its root as emetic and purgative. After long neglect this plant has obtained a foothold in the French Codex, which recognizes a Resina Thapsiae prepared by exhausting the bark of the root with alcohol and evaporating to a soft extract. From this extract the Codex further directs that an Emplastrum Thapsiae shall be so prepared as to contain 7 per cent. of the resin combined with yellow wax, turpentine and colophony. The bark of the root and the resin are both objects of commerce. The bark is described by Stanislaus Martin as almost always doubly quilled, unless where altogether in small fragments, exteriorly rugose with the epidermis here and there detached in patches larger or smaller, and of a deep brown color, interiorly smooth and whitish and of a fibrous fracture. The size of the pieces varies, the largest not exceeding 6 dm. in length and 2.5 in width. It is said that great care is necessary, in removing the root from the bales, not to be injured by the powder which escapes, and which causes itching and swelling of the face and hands. By submitting thapsia to the successive action of alcohol and ether Pressoir obtained two resins. (J. P. C., 4e ser., xi, 328.) Canzoneri finds that the ethereal extract is an amber-colored syrupy resin possessing vesicating properties. From it he has obtained two acids, octoic or caprylic acid, and thapsic acid, besides a neutral non-nitrogenous vesicating substance. (See A. J. P., vol. xiv, 325.) Cazenave objects to the plaster prepared from the resin and kept in masses, as it deteriorates by time. He proposes the following method of preparing a plaster extemporaneously when wanted. Dissolve the resin in alcohol and with the aid of a brush spread it on a suitable recipient, which may be of ordinary plaster, waxed taffetas, or simply gummed paper. A single layer is sufficient for the purpose of an active revulsion, but the effect may be increased at pleasure by increasing the number of layers. (J. P. C., 1868, 29.) The French thapsia, plaster is an exceedingly active counter-irritant, producing much inflammation of the skin with an eczematous eruption and intolerable itching and, if the application be maintained, finally an ulcerated and suppurated surface, which on healing leaves behind it pronounced scars. The therapeutic action of the plaster is that of a severe counter-irritant.
The resin from the root of Thapsia Sylphium St.-Laz., an Algerian plant, which most botanists believe to be a simple variety of T. Garganica L. is, according to Herlaut, more active than that of the official plant. (Proc. A. Ph. A., xxvi, 250.) Heckel and Schlagdenhauffen (N. R., June and July, 1887) find in the root of Thapsia villosa L. a vesicant resin, which acts more slowly and gently than does that of T. Garganica.