107. Taxus baccata, Linn.—Common Yew.
Sex. Syst. Dioecia, Monadelphia.
(Folia et semina.)
Σμιλαξ, by some called ζυμαλος, by the Romans termed ταξος, Dioscorides, lib. iv cap. 80.—Taxus, Pliny, lib xvi. cap. 20 et 33; and lib. xxiv. cap. 72.—A tree often attaining a considerable bulk. Leaves scattered, nearly sessile, 2-ranked, crowded, linear, acute, entire, very slightly revolute, about 1 inch long, dark green, smooth and shining above, paler with a prominent midrib beneath, terminating in a small harmless point. Flowers axillary sessile. Fruit drooping, consisting of a succulent, sweet, internally glutinous, scarlet cup, inclosing an oval, brown, unciform seed, unconnected with the fleshy part.—In 1828, Peretti [Journ. de Pharm. t. xiv. p. 537, 1828.] analyzed yew (the leaves?), and obtained a bitter volatile oil, a bitter non crystallizable substance, a yellow colouring matter, resin, tannin, gallic acid, chlorophylle, mucilage, sugar, and malate of lime. In 1818, Chevallier and Lassaigne [Ibid. t. iv. p. 558, 1818.] examined the pulpy cup of the fruit, and found in it a non crystallizable fermentable sugar, gum, malic and phosphoric acids, and a carmine-red fatty matter. In 1843, Martin [Jahresbericht über d. Fortschritte d. Pharm. in Jahre 1843, S. 18.] analyzed the seeds, and obtained from them a volatile oil having a terebinthinate odour, fixed oil, a green very bitter resin, sugar, albumen (in small quantity), sulphate of lime, and vegetable fibre.
The poisonous properties of yew were known to the ancient Greeks and Romans, and have been fully established by modern experience, although some few writers have expressed doubts concerning them. Percival [Essays, Med. Phil. and Exper. vol. iii. p. 257.] states that three children were poisoned by the fresh leaves. Dr. Mollan [Dublin Hospital Gazette, May 15, 1845, p. 109.] has mentioned the case of a lunatic who died in 14 hours after taking yew-leaves: the symptoms were giddiness, sudden prostration of strength, vomiting, coldness of the surface, spasms, and irregular action of the heart. Mr. Hurt [Lancet, Dec. 10, 1836.] has reported an interesting case of a child, three years and a half old, who died in less than four hours after eating the fruit: the symptoms were vomiting, convulsions, purple lips, and dilated pupil. Considered both in a toxicological and therapeutical point of view, the yew appears to hold an intermediate positipn between savin and foxglove. To savin it is allied by its botanical affinities and chemical composition, but also by its acrid, evacuant, diuretic, and emmenagogue properties. But, on the other hand, its relation to the neurotics, especially to sedatives (see vol. i., p. 258), is marked by the giddiness, irregular and depressed action of the heart, convulsions, and insensibility which it produces. It is said that, when used for medicinal purposes, it is unlike digitalis, in not being apt to accumulate in the system. As a poison it belongs to the class of acro-narcotics; as a medicine it is used as a sedative, antispasmodic, emmenagogue, lithic, and resolvent. As a sedative it has been proposed by Rempinelli and Martin to be used as a substitute for, and under the same indications as, digitalis. As an emmenagogue it has been given in cases similar to those for which savin is sometimes administered. Dr. A. Taylor [On Poisons, p. 790.] says that "infusion of yew-leaves, which is popularly called yew-tree tea, is sometimes used for the purpose of procuring abortion by ignorant midwives." As a lithic it has been employed in calculous complaints; as an antispasmodic in epilepsy and convulsions; as a resolvent in hepatic and gouty complaints. In pulmonary and vesical catarrh it has likewise been used. The powder of the leaves or seeds is given in doses of from half a grain to two or three grains. The extract of the leaves (extractum taxi, Cod. Hamb.), prepared by evaporating the expressed juice of the leaves, is administered in doses of one or two grains, and gradually increased. The alcoholic and ethereal extract of the seeds is employed in doses of from 1/6th or 1/3d of a grain. In cases of poisoning by yew, the first indication is to expel the poison from the stomach by the means already pointed out (see vol. i., p.201). The sedative and narcotic effects are to be counteracted by stimulants such as ammonia (see the treatment for poisoning by foxglove).