Many fungi are poisonous, and a still larger number frequently prove indigestible and unwholesome. The same species which may be taken with impunity by one individual will excite in another various inconveniences, such as nausea, vomiting, griping, diarrhoea, &c. Dyspepsia, and a highly susceptible condition of the nervous system, such as that called the hysterical constitution, dispose to those ill effects, which, in other cases, are ascribed to idiosyncrasy of constitution.
It must be obvious from these remarks that there can be no absolute anatomical characters by which the unwholesome can be distinguished from the wholesome species; the effects greatly depending on the constitution of the eater, or on some other insufficiently determined circumstances. An illustrative fact of the truth of this statement has been adduced in the case of a French officer and his wife, who died in consequence of breakfasting off some poisonous Agarics, which were nevertheless eaten by other persons in the house with impunity. These, and other circumstances, have led to a general distrust of all fungi, except the cultivated ones and so strongly was the late accomplished botanist, Professor L. C. Richard, impressed with this feeling, that, though no one was better acquainted with the distinctions of Fungi than he was, yet he would never eat any except such as had been raised in gardens in mushroom beds.
Of the genus Agaricus, all those species which belong to the subgenus Amanita are either actually poisonous or highly suspicious. The characters of this subgenus are thus laid down by the Rev. M. J. Berkeley:—
Amanita (a name given to some esculent Fungus by Galen). Veil double: one universal, covering the whole plant in a young state, distinct from the epidermis, at length burst by the protrusion of the pileus, part remaining at the base of the stem, part either falling off, or forming worts on the pileus; the other partial, at first covering the gills, and afterwards forming a reflected subpersistent ring on the top of the stipes. Stem puffed, at length hollow, squamoso fibrillose, thickened at the base. Pileus with the disk fleshy, the margin thin, campanulate, then plane; viscid, when saturated with moisture. Gills attenuated behind, free, broader in front, ventricose, close, but little unequal; when full-grown, denticulated.
One of the most remarkable species of this subgenus is the AGARICUS MUSCARIUS, Linn. (Amanita muscaria, Greville), the remarkable effects and uses of which have been already noticed (see ante, vol. i. p. 152).
The Russians, who eat no less than sixteen species of agaricus [For some remarks on the Fungi used as food by the Russians, see Lyall's Character of the Russians, and a detached History of Moscow, p. 556, Lond. 1823.], never employ any belonging to the subgenus Amanita [Dr. Lefevre, Lond. Med. Gaz. xxiii. 414.].
Besides the species of the subgenus Amanita, many other Agarici are poisonous or suspicious.
The symptoms produced by poisonous fungi are those indicating gastro-intestinal irritation (nausea, vomiting, purging and abdominal pain), and a disordered condition of the nervous system (delirium, stupor, blindness, convulsions, muscular debility, paralysis, and drowsiness). In some cases, the power of the vascular system is remarkably depressed, the pulse being small and feeble, the extremities cold, and the body covered with a cold sweat. At one time, local irritation only; at another, narcotism alone is produced [For illustrations of the effects of particular species, consult Phoebus, Deutschl. kryptog. Giftgewächse, 1838; and Letellier, Journ. de Pharm. Août, 1837.].
In some cases the active principle of poisonous fungi seems to be a volatile acrid principle; in other instances it is a brown, uncrystallizable solid, called by Letellier amanitin.
No specific antidote is known. The first object, therefore, is to expel the poison from the stomach and bowels. The subsequent treatment will depend on the nature of the symptoms which manifest themselves, and must be conducted on general principles [For further information respecting poisonous fungi, consulut Christison's Treatise on Poisons.].