1 Spec. Plant Willd. i. 1395. Cl. 5. Ord. 2. Pentandria Digynia. Nat. ord. Umbelliferae. G. 533. Partial involucre halved, three-leaved. Fruit nearly globular, five-streaked, notched on each side. Species 1. Conium maculatum. Common hemlock. Med. Bot

3d edit. 104. t. 42. Smith, Flora Britan. i. 302. Officinal. Conii folia, fructus, Lond. Conii maculati folia,

Edin. Dub. The leaves and seed of Hemlock.

Syn. Cigue ordinaire (F.), Geflecter Schierling (G.), Gevlakte Scheerling (Dutch), Skarntyde (Dan.), Sprackligodort (Swed.), Swinia wesz (Pol.), Boli-golou (Russian), Cicuta maggiore (I.), Conio manchado (S).

Hemlock is a biennial, umbelliferous, indigenous plant, growing under hedges, by road-sides, and among rubbish, flowering in June and July. The root, which is fusiform, branching, whitish, and fleshy, exudes, when cut, a milky juice. The stem rises erect about four or five feet in height, is branching and leafy, round, hollow, striated, smooth, shining, and maculated with brownish purple. The lower leaves are very large, above a foot in length, on large sheathing petioles, supradecompound, and shining; the upper ones are bipinnate; the whole stand upon channelled footstalks, proceeding from the joints of the stem, are incised, smooth, of a deep green colour on the upper surface, but paler underneath. The rays of the umbels are ten or twelve, those of the umbellules fifteen or sixteen. The involucre consists of from three to seven sho rt, turned-down, lancet-shaped, leaflets, with white edges spre ad at the base; the involucel of three or four leaflets on one side only, and spreading. The flowers are very small; the petals white, the outer ones rather larger than the inner, cordate, inflected; the stamens the length of the petals, supporting white orbicular anthers; the styles two, filiform, diverging, and crowned with round stigmas.

The fruit is ovate, strated, smooth, and brownish when ripe.

Dioseoridis. Cicuta vulgaris major, Park, 932. Cicuta, Bod. 461.

Hemlock is distinguished from other umbelliferous plants, with which it may be confounded by its large and spotted stem1, the dark and shining colour of its lower leaves, and their disagreeable smell, when fresh and bruised, resembling in some degree the urine of a cat.2

For medical use, the leaves should be gathered about the end of June, when the plant is in flower; the small leaflets picked off, and the footstalks thrown away. The picked leaflets are then to be properly dried (vide Powders, Part III.); and as exposure to the air and light destroys the fine green colour of the plant, which is supposed to injure its active qualities, the dried leaflets must be preserved in boxes completely filled by gently pressing down the leaves, then covered with a closely-fitted lid, wrapped in paper, and sealed; or, if powdered, the powder may be preserved good in closely-stopped opaque phials, for many years.

Qualities.-The odour of properly dried hemlock-leaves is strong, heavy, and narcotic, but not so disagreeable as that of the fresh leaves : the taste is slightly bitter and nauseous. They are easily pulverized; and the powder should retain the beautiful green colour of the leaves. The acrimony only of the fresh leaves is lost in drying : but the narcotic principle remains uninjured if the operation be well performed. The seeds are small, ovate, striated with five ribs, and of a greyish-green colour. The virtues of conium are extracted by alcohol and sulphuric ether. To ether the leaves communicate a very deep green colour; and when the etherial tincture is evaporated on the surface of water, a rich dark-green resin remains, in which the narcotic principle of the plant appears to reside: it contains the odour and taste in perfection; and half a grain produces headach and slight vertigo. To this principle, which I discovered, Dr. Paris proposes to give the name of Conein1', but it merely contains Conein or Conia as one of its components. Brandes has discovered a particular principle of an alkaline nature, which he terms Cicutine, of a green colour, insoluble in water, and in doses of half a grain causing vertigo and headach.

But it is to Professor Geiger of Heidelberg that the profession is indebted for the knowledge of the active principle of Conium. In 1827 Gi-seske had observed that in distilling hemlock and water with caustic lime, a strong odorous alkaline fluid was procured, which, when neutralized by sulphuric acid, formed a substance which was readily separated by alcohol, and was highly poisonous, its properties being the same as those of hemlock in a concentrated degree. Geiger in 1831, taking a hint from this result of Giseske's experiment, distilled the seeds of hemlock with water and caustic potassa, and obtained a fluid, which he neutralized with sulphuric acid, and redistilled; water only passed over, and a substance of the consistence of syrup remained in the retort. This was treated with strong alcohol, which precipitated sulphate of ammonia: the alcohol was then separated from the solution by distillation, and the residue being mixed with water and caustic potassa, and redistilled with a gentle heat, a colourless transparent oily-looking substance was procured floating on the water in the receiver.

This being separated was found to possess properties of the most active kind: it was called Conia by Geiger.

1 The Chaerophyllum bulbosum, bulbous-rooted cow parsley, has a spotted stem, but the joints are swelled, and the seeds rough.

2 In Ray's Synopsis, Conium maculatum is named Cicuta,-a name still retained by the Dublin College; and owing to which the water hemlock, Cicuta virosa, has sometime been confounded with it, and improperly used.

Conia has a powerful odour, resembling that of hemlock and tobacco, and an extremely acrid bitter taste: it is soluble in water, has an alkaline re-action, and forms salts with the acids. According to Liebig, it is a compound of 66.91 of carbon, 12.0 hydrogen, 8.28 oxygen, and 12.8 of nitrogen. From xl. . of the seeds Dr. Christison procured ij.ss. of hydrated Conia. Dr. Christison made a series of interesting experiments on animals with this substance, which demonstrated that it operates with incredible energy on the nervous system, although its first influence is as a local irritant: it causes rapid paralysis, first of the voluntary muscles, then of the diaphragm and the respiratory muscles, and destroys by asphyxia. The heart remains unaffected. Few poisons equal Conia in subtilty and swiftness.2

Medical properties and uses, - Hemlock is a powerful narcotic, and is used as such both internally and as an external application. Stoerck, whose publications first brought it into general notice, rated its powers too high; and the multitude of discordant diseases which he enumerated as yielding to it, led many sober men to doubt its efficacy altogether. Hemlock is, nevertheless, a useful narcotic; and, if it have not succeeded in curing cancer in the hands of British practitioners, it has been advantageously used as a palliative in both scirrhous and open cancer, abating the pain, and allaying the morbid irritability of the system. It has also been found serviceable in chronic rheumatism; scrofulous, syphilitic, and other ill-conditioned ulcers, and glandular tumors; in pertussis, and the protracted cough which often remains after pneumonic inflammation. In America it has been used in bronchocele with advantage.1 An over-dose of it produces sickness, vertigo, delirium, dilatation of the pupils, great anxiety, laborious respiration, coldness of the limbs, asphyxia.2 The best antidote is vinegar, after the stomach has been evacuated, and the cerebral excitement reduced by bleeding and purging.

1 Pharmacologia,p. 185. 2 Trans, of Roy. Soc. Edin. vol. xiii.

The powder of the dried leaves, if well preserved, and the extract, are the best forms of this remedy. Hufeland recommends the fresh expressed juice from xij. to lx. for a dose. The dose of the powder is grs. v. to grs. xxx.; that of the extract grs. v. to Эj.: but both may be gradually increased every day, until a slight vertigo forbids the further increase. The Edinburgh and Dublin Colleges have long ordered a tincture, and it is now also admitted into the London Pharmacopoeia.

Officinal preparations.-Extractum Conii, L. E. D. Tinctura Conii, L. E. D. Unguentum Conii, D. Cataplasma Conii, D.