Aspidium Filix mas, or male fern, is a European plant, with a horizontal root or rhizome, from which numerous fronds or leaves rise, to the height sometimes of three or four feet. it has been thought to be also a native of the United States; but there seems to be some doubt about the perfect identity of the two plants, and the probability is that they are not of the same species.

The root or rhizome, as taken from the earth, is long, cylindrical, and closely invested with the remains of the footstalks of the fronds, between which appear brown silky scales, with radical fibres emerging. But, as in the shops, it is generally much broken up, so as to exhibit little of its original appearance when whole. The proper rhizome is brownish externally, yellowish or reddish-white internally, of a faint but peculiar odour, and a sweetish, astringent, bitterish, and nauseous taste. Water but imperfectly extracts its virtues.

Though the active principle has not been obtained in a pure state, Peschier has made the important discovery, that the virtues of the medicine reside in the ethereal extract. This is a thick, dark liquid, with the odour of the root, and a bitterish, subacrid, nauseous taste, and consists of fixed oil, volatile oil, resin, etc. The male fern root, found in the shops in this country, has generally been so much deteriorated by time, as to be of little value; and the remedy had fallen into almost entire neglect, when the fact was ascertained that it was possible to obtain its properties in a concentrated and permanent form. Now that we can, by importation, provide ourselves with the ethereal extract, prepared from the root in its fresh state and highest activity, we may hope to realize, in our own experience, what has not hitherto been done, the great efficacy of the remedy in tapeworm, established beyond doubt by abundant experience in Europe.

Medical Effects. Male fern has little effect on the human system. It may be slightly tonic, but it is only for its anthelmintic properties that it is employed. These were known to the ancients, and did not of course entirely escape the attention of the diligent students of the old Greek and Roman medical writers; but the profession in modern times were generally quite ignorant of them; so that the announcement that male fern was the chief ingredient of Madame Nouffers famous specific took them by surprise. It is unnecessary to repeat the so often told tale, of the reputation of this nostrum in the cure of tapeworm, of the purchase of the secret by the king of France, and of its public announcement about the year 1775. It immediately acquired great reputation, and was submitted to many trials, the general result of which has been favourable to the efficiency of the remedy, though it not unfrequently fails-, and is certainly not entitled to the name of a specific. It is chiefly in the treatment of the common tapeworm that it is still employed. Dr. Kiich-enmeister found the ethereal extract to destroy the taenia, out of the body, in from three and a half to four hours, while, under the action of castor oil, the worm lived eight hours; so that it has undoubtedly considerable anthelmintic virtue, though much inferior, according to his experiments, to the oil of turpentine and koosso. The root should be given in powder or ethereal extract. The dose of the powder is from a drachm to half an ounce, which may be administered mixed with syrup in the form of an electuary, or suspended in the state of liquid mixture, and repeated morning and night on an empty stomach, for one, two, or three days, and then followed by a brisk cathartic. The ethereal extract may be taken in the dose of from fifteen to thirty drops, or about the same number of grains, repeated, and followed by a cathartic, as in the case of the powder.

The British Pharmacopoeia gives directions for preparing this extract, which it denominates Extractum Filicis Liquidum. The preparation belongs properly to the oleoresins (oleoresinae) of the U. S. Pharmacopoeia, though it is not recognized in that work. it is prepared simply by exhausting the root with ether, by percolation, and distilling off that fluid by means of a water-bath. it is a thick, dark liquid, with the odour of fern, and a nauseous, bitterish, and subacrid taste. it consists mainly of the oil and resinous matter of the root, and has long been used on the Continent of Europe under the name of oil of fern. The dose is given above.