Deadly Nightshade. Deadly Dwale. Nat. Ord. Solanaceae. Linn. Syst. Pentandria Monogynia. Hab. England, Northern Europe. Flowers in June and July.

Med. Prop. and Action. The leaves (off.) are anodyne and anti-spasmodic in doses of gr. j., gradually increased until they produce dryness of the throat, and other constitutional symptoms. Their power of dilating the pupil renders them particularly valuable in diseases of the eye. Their activity is chiefly due to an alkaloid, Atropia (which see), and partly, also, to another principle, Belladonnine, first described by Luebekind. The best form for internal use is the Extract, in doses of gr.1/6 - gr. j., gradually increased until constitutional effects are observed, or the desired end is obtained (An easy test of the activity of the Extract is to rub a grain or two on the eyelids. If good, it should produce full dilatation of the pupil in the course of a minute or two.) Belladonna, in doses of gr. j. gradually increased as above, allays pain and morbid irritability, and causes a particular dryness of the mouth and fauces, attended by considerable thirst. In larger or long-continued doses, its effects are dilatation of the pupil, dimness of sight, vertigo, giddiness, and a species of intoxication; the pulse small and frequent; the dryness of the mouth and fauces so greatly increased as to cause difficulty of swallowing The alteration of vision appears to be due to the production of presbyopia from want of adjusting power of the eye, and not to diminished sensibility of the retina. (Garrod. *) It should be immediately discontinued on the appearance of any of these symptoms. In poisonous doses, all the above symptoms are present in an aggravated form. The delirium which occurs is of a cheerful kind, attended with fantasies which cause laughter. Death is preceded by convulsions and paralysis. The occasional symptoms present are - 1. An eruption on the skin, resembling that of Scarlatina; 2. Irritation of the genito-urinary organs; 3. Amaurosis; 4. Numbness, and swelling of the face; 5. Aphonia; 6. A state termed Microscopia, or Micropia, in which state all objects appear much smaller than natural. It has only been observed, and that rarely, when Belladonna has been locally applied to the eye. The manner in which Belladonna causes dilatation of the pupil is yet undecided. Muller attributes it to a paralysing influence on the ciliary nerves; Mr. Wharton Jones, to a diminution for a time of the general sensibility of the retina conferred by the ofth nerve; and Mr. Adams considers that its operation is limited to the radiating fibres of the iris. Dilatation of the pupil equally occurs, whether the medicine be applied locally to the eye, or is taken internally; but in the latter case it is attended by great constitutional derangement. By continued use it does not generally lose this property; thus, Mr. Lawrence mentions two patients of his own, one of whom used it habitually for four of five years, and the other for fourteen or fifteen years; and it dilated the pupil just as well at the end of these periods as at the commencement. Occasionally, however, it loses its dilating power, but regains it if the application be suspended for a week or two, and then resumed. Alkalies, especially Liquor PotassAe, entirely destroy this property, and should not, therefore, be combined with it. When Belladonna is given internally, it should be commenced in small doses, until it produces some of the above constitutional symptoms in a slight degree; but if, when these appear, the disease does not yield, its continued employment is useless, and perhaps injurious. The antagonism between Belladonna and Opium is considered in art. Opium. Mr. Hughes, in an able paper, shows that the chief physiological effects, as well as therapeutic uses of Belladonna as an internal remedy, depend upon the influence it exercises on the Pneumogastric nerve. Externally, it is used in the form of ointment, plaster, fomentation, or poultice.

* Edin. Monthly Journal, vol. ii. p. 304.

Journ. de Med., t. lvi. p. 115. Lancet, Feb. 1, 1862, p. 134.

Offlc. Prep. Of the leaves. 1. Emplastrum BelladonnAe (Ext. of Belladonna oz. iij.; Soap Plaster oz. iss.; Resin Plaster oz. iss.).