Muscarine is a colourless, strongly alkaline, syrupy fluid, which, if allowed to stand over sulphuric acid, becomes gradually crystalline, but liquefies again on exposure to the atmosphere. It dissolves in water in every proportion, and also in alcohol, but is very little soluble in chloroform, and insoluble in ether. It is not precipitated by tannin: it forms salts with acids, and gives precipitates with auric chloride, phosphotungstic, and phosphomolybdic acids, and also with potassio-mercuric iodide. The last precipitate is at first amorphous, but it gradually becomes crystalline. This was the compound used by the discoverers to separate the base. With many other general alkaloidal reagents muscarine forms no compound that is insoluble, and therefore gives no precipitate, such, e.g., as iodine with potassic iodide, picric acid, and platinic chloride. Muscarine is a stronger base than ammonia, and precipitates copper and iron oxides from solutions of their salts. Muscarine is very poisonous; 2 to 4 mgrms. are sufficient in subcutaneous injection to kill cats in from two to twelve hours—larger doses in a few minutes; but with rabbits the action is less intense. Cats become salivated, their pupils contract, they vomit, and are purged, the breathing becomes frequent, and there is marked dyspnœa. At a later stage the respirations are slower, and there are convulsions, and death.
The alkaloid has also been tried on man. Doses of from 3 to 5 mgrms., injected subcutaneously, cause, after a few minutes’ profuse salivation, increased frequency of the pulse, nausea, giddiness, confusion of thought and myosis, but no vomiting, and no diarrhœa. Small quantities applied to the eye cause, after a few minutes, a derangement of the accommodation, but no change in the size, of the pupil; larger quantities cause also myosis, which depends upon an excitement of the sphincter iridis, or of the oculomotorius.
§ 519. The actions of muscarine and atropine are to a great extent antagonistic. This is especially and beautifully demonstrated by the effects of the two substances on the frog’s heart. The action of muscarine upon the heart is to excite the inhibitory nerve apparatus, while the action of atropine is to paralyse the same system. One mgrm. of muscarine, injected subcutaneously into a frog, arrests the heart in diastole, but if a suitable dose of atropine is applied to the heart thus arrested, it begins to beat again; or, if atropine is first given, and then muscarine, the heart does not stop. The muscarine heart, when it has ceased to beat, may be successfully stimulated by galvanism. Muscarine at first excites the respiratory centre, and then paralyses it.
§ 520. Detection of Muscarine in the Body.—Muscarine itself is not likely to be taken as a poison or administered; but if it is sought for in the fly-blown agaric, or in the tissues or organs of persons who have been poisoned by the fungus, the process of Brieger appears the best. The process depends upon the fact that muscarine gives a soluble mercuric chloride compound, and is not precipitated by chloride of platinum, whilst most other substances accompanying it give more or less insoluble precipitates. The substances are treated with water acidulated with hydrochloric acid, and the acidulated extract concentrated (best in a vacuum) to a syrup. The syrupy residue is now treated with water, and the solution precipitated by means of mercuric chloride solution and any precipitate filtered off; the filtrate is freed from mercury by SH2, and evaporated to a syrup; the syrup is repeatedly extracted with alcohol, and the alcoholic solution precipitated with platinum chloride and any precipitate filtered off. The filtrate is freed from alcohol, and all the platinum thrown out of solution by SH2; the aqueous filtrate is now concentrated to a small volume, and again platinum chloride added, any precipitate which forms is filtered off, and the final filtrate allowed to crystallise. If muscarine be present, a crystalline compound of muscarine platinum chloride will form.
The crystals are usually octahedral in form, and have the composition (C5H14NO2Cl)2PtCl4; the percentage of platinum is 30·41.
It would probably be necessary to identify farther, by the action of the poison on a frog.
§ 521. The Agaricus phalloides, a common autumn fungus, has been several times mistaken for mushrooms, and has proved fatal; of some 53 cases collected by Falck, no less than 40, or 75 per cent., were fatal; the real mortality is much lower than this, for it is only such cases that are pronounced and severe which are likely to be recorded. The fungus contains a toxalbumin which has been named “phallin.” The action of this toxalbumin is to dissolve the blood corpuscles; according to Kobert, even one 250,000th dilution produces “polycholie,” with all its consequences, such as the escape of hæmoglobin and its decomposition products in the blood and urine, multiple blood coagulation through the fibrin ferment becoming free, and serious cerebral disturbance. If into a dog, cat, or rabbit, only 0·5 mgrm. of phallin be injected intravenously, within from twenty to thirty minutes blood from a vein shows that the serum has a red colour.
The symptoms in man first appear in from three to forty-eight hours; there is mostly diarrhœa, violent vomiting, with cramp in the legs, cyanosis, and collapse. There are also nervous phenomena, convulsions, trismus, and, in a few cases, tetanic spasms. The pulse, in seven cases described by Maschka, was very small, thready, and quick, but in others, again, small and slow. The pupils have in some cases been dilated, in others unchanged. Death is generally rapid. In two of Maschka’s cases from sixty to sixty-eight hours after the investigation, but in the rest from twelve to eighteen hours. Life may, however, be prolonged for several days. In a case recorded by Plowright,[557] in which a boy had eaten a piece of the pileus, death occurred on the fourth day.
[557] Lancet, 1879.