The usual mode of raising mushrooms, in beds prepared with layers of horse-droppings and fine mould, is gene rally understood, and has been fully described in a preced ing part of this work, (art. FUNGI.) It may be proper, however, in addition to what is there said, to give an ac count of what is called Oldacre's plan, this being gene rally considered as an improvement on the culture of mushrooms.
453. Mr Isaac Oldacre is an Englishman, who for many years held the office of chief gardener to the Emperor of Russia at St Petersburgh. In 1814, he visited iris native country ; and on that occasion, at the desire of Sir Joseph Banks, put in practice at Spring Grove his improved mode of raising mushrooms. In forming the compost for the beds, he prefers fresh short dung, from a stable or the path of a horse-mill, The dung must neither have been exposed to wet nor to fermentation. About a fourth or a sixth part of cow or sheep's droppings is added, and the whole ingredients are well mixed and incorporated. The beds, if they may be so called, are formed on shelves, or in drawers or boxes, in the mushroom-house, or in any out house, where a slight increase of temperature can be com manded. A stratum of the prepared mixture, about three inches thick, being deposited, is beat together with a flat wooden mallet. Another similar layer is added, and beat together as before ; and this is repeated, till the beds be six inches thick, and very compact. A degree of fermenta tion soon takes place in/this mass ; but if the heat arising from this process be not quickly perceptible, another layer must still be added, till sufficient action be excited. When the beds arc milk warm, (or between 80° and 90° Fahr.) some holes are dibbled about nine inches apart, for receiv ing the spawn. These are left open. for some time ; and when the heat is on the decline, but before it be quite gone, a lump of spawn is inserted into each opening, and the holes are then filled up with the compost. Ten days afterwards, the beds are covered with a coating of rich mould, mixed with a fourth or sixth part of droppings, to the depth of an inch and a half. This is beat down with the back of a spade, and the bed may then be accounted ready for producing. The mushroom-house is now kept as nearly and equally at 55' Fahr. as circumstances will al low. When the beds become very dry, it is occasionally found requisite to sprinkle over them a little water, taken from a pond or river ; but this must be done with great circumspection.
Beds thus prepared, we are assured, yield abundant crops of mushrooms. If a number of shelves or drawers be at first prepared, a few only, at a time, may be covered with mould, and brought into bearing ; the rest of the shelves or drawers being cropped in succession, as mush rooms may happen fo be in demand. It is evident that they
may thus be procured at all seasons. The more that free air can be admitted into the mushroom-house, the flavour of the mushrooms will be found to be improved.
In what particulars the advantage of Mr Oldacre's plan over former modes chiefly consists, does not very clear ly appear. Beds made up in the usual way are much less compact, and are more damp : compactness and dryness may therefore be considered as important. Indeed, the beneficial effects of keeping the spawn dry were long ago noticed by Miller, in his Dictionary, who found, that spawn which had lain for four months near the furnace of a stove, yielded a crop in less time and in greater profusion than any other.
In some old authors, a very sage advice is given for promoting the fecundity of mushroom beds constructed on the ordinary plan, viz. to take a few full grownenushrooms from pastures, and, breaking them down in the watering pot, to water the beds with the infusion. This is plainly nothing else than sowing mushroom seed, the minute seeds lodged in the gills being thus suspended in the water, and introduced along with it into the bed.
454. Although the Agaricus campestris is the only spe cies cultivated, it is not the most delicate of the tribe as to flavour, nor perhaps the best deserving of culture. Sonic of the others should be tried, and there seems no reason to doubt of ultimate success. A.aurantiacus possesses ex cellent qualities ; the flesh is tender, and the flavour deli cate : it is in high repute on the Continent, where it is ga thered in pine forests, about the end of sl1111111er. It is the orange of the French, and is distinguished from another species, called the false orange, by having a complete vulva. A. solitaries is remarkable for its line flavour. A. procerus is a great favourite in France, where it is known by the name of griselie. A. deliciosus is much used in Germany and Italy ; but though it is not uncommon in our fir plan tations, it is scarcely ever eaten in this country. The Champignon (4. nratensia) is used in soups, and is there fore occasionally brought to market ; but, as remarked by Mr Sowerby, in " English Fungi," it is apt to be confound ed, by the common mushroom gatherers, with A. virosus, one of the most to be avoided. A. violaceus is sometimes sold in Covent Garden, under the name of Bluets : it is a harmless kind, but has no other meth. The species which most commonly forms the circles and semicircles on downs near the sea-shore, called fairy-rings, is A. orcades. This Mr Lightfoot, in his Flora Scolica, considers as the waits serail of the French ; but their tnousseron is A. virgineus of Persoon, a fleshy species, nearly of a pure white colour, while our plant is coriaceous and buff-colnured.