Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/87

Rh MUSHROOM 75 white, then rose-coloured, at length brown-black. A point of great importance is to be noted in the attachment of the gills near the stem at o, p ; the gills in the true mush room are (as shown) usually more or less free from the FIG. 1. Pasture Mushroom (Agaricus campesiris, L.). stem, they never grow boldly against it or run down it ; they may sometimes just touch the spot where the stem joins the bottom of the cap, but never more; there is usually a slight channel, as at p, all round the top of the stem. When a mushroom is perfectly ripe and the gills are brown- black in colour, they throw down a thick dusty deposit of fine brown-black or purple-black spores ; it is essential to note the colour. The spores on germination make a white felted mat, more or less dense, of mycelium ; this, when compacted with dry, half-decomposed dung, is the mush room spawn of gardeners (see HORTICULTURE, vol. xii. p. 284). The stem is firm, slightly pithy up the middle, but never hollow ; it is furnished with a floccose ring near its middle, as illustrated at Q, Q ; this ring originates by the rupture of the thin general wrapper K of the infant plant. On being cut or broken the flesh of a true mushroom re mains white or nearly so, the flesh of the coarser Horse Mushroom changes to buff or sometimes to dark brown. To summarize the characters of a true mushroom : it grows only in pastures ; it is of small size, dry, and with unchange able flesh ; the cap has a frill ; the gills are free from the stem, the spores brown-black or deep purple-black in colour, and the stem solid or slightly pithy. When all these characters are taken together no other mushroom -like fungus and nearly a thousand species grow in Britain can be confounded with it. Like all widely - spread and much - cultivated plants, the edible mushroom has numerous varieties, and it differs in different places and under different modes of culture in much the same way as our kitchen-garden plants differ from the type they have been derived from, and from each other. In some instances these differences are so marked that they have led some botanists to regard as distinct species many forms usually esteemed by others as varieties only. A small variety of the common mushroom found in pastures has been named A. pratensis (Vitt.); it differs from the type in having a pale reddish -brown scaly top, and the flesh on being cut or broken changes to pale rose-colour. A variety still more marked, with a darker brown cap and the flesh changing to a deeper rose, and sometimes blood-red, has been described as A. rufescciis (Berk.). The well-known compact variety of mushroom-growers, with its white cap and dull purplish clay-coloured gills is A. hortcnsis (Cke. ). Two sub-varieties of this have been described under the names of A. Buchanani and A. elongatus, and other distinct forms are known to botanists. A variety also grows in woods named A. silvicola (Vitt. ) ; this can only be distinguished from the Pasture Mushroom by its elongated bulbous stem and its externally smooth cap. There is also a fungus well known to botanists and cultivators which appears to be intermediate between the pasture variety and the wood variety, named A. vaporarius (Otto). The large rank Horse Mushroom, now generally referred to as A. arvcnsis (Sch. ), is prob ably a variety of the Pasture Mushroom ; Sowerby has described it under the name of A. Gcorgii and Dr P&amp;gt;adham as A. exquisitus ; it has also been published as A. cdulis. It grows in rings in woody places and under trees and hedges in meadows ; it has a large scaly round cap, and the flesh quickly changes to buff or brown when cut or broken ; the stem too is hollow. An unusually scaly form of this has been described as A. villaticus and another as A. augustus. Dr Badham has also described a variety under the name of A. anccps. A species, described by Berkeley and Broome as distinct from both the Pasture Mushroom and Horse Mushroom, has been pub lished under the name of A. clvcnsis. This grows under oaks, in clusters, a most unusual character for the mushroom. The species is said to be excellent for the table. An allied fungus peculiar to woods, with a less fleshy cap than the true mushroom, with hollow stem, and strong odour, has been described as a close ally of the Pasture Mushroom under the name of A. silvaticus (Sch.); its qualities for the table have not been described. Many instances are on record of symptoms of poisoning, and even death, having followed the consumption of plants which have passed as true mushrooms ; these cases have probably arisen from the examples consumed being in a state of decay, or from some mistake as to the species eaten. It should always be specially noted whether the fungi to be consumed are in a fresh and wholesome condition, otherwise they act as a poison in precisely the same way as does any other semi-putrid vegetable or putrid meat. Many instances are on record where mushroom-beds have been invaded by a growth of strange fungi and the true mushrooms have been ousted to the advantage of the new-comers ; such instances are very perplexing, but they tend to show that a proper supervision should be kept over fungi when used for food as over other vegetables, fruit, meat, and fish. When mushrooms are gathered for sale by persons unacquainted with the different species mistakes are of frequent occurrence. A very common spurious mushroom in mar kets is A. vclutinus (P.), a slender, ringless, hollow-stemmed, black- gilled fungus, common in gardens and about dung and stumps ; it is about the size of a mushroom, but thinner in all its parts and far more brittle ; it has a black hairy fringe hanging round the edge of the cap when fresh. Another spurious mushroom, and equally common in dealers baskets, is A. lacrymabundns (Fr.) ; this grows in the same positions as the last, and is somewhat fleshier and more like a true mushroom ; it has a hollow stem and a slight ring, the gills are black-brown mottled and generally studded with tear- like drops of moisture. In both these species the gills distinctly touch and grow on to the stem. Besides these there are numerous other black -gilled species which find a place in baskets, some species far too small to bear any resemblance to a mushroom, others large and deliquescent, generally belonging to the stump- and dung- borne genus Coprinus. The true mushroom itself is to a great ex tent a dung-borne species, therefore mushroom-beds are always liable to an invasion from other dung-borne forms. The spores of all fungi are constantly floating about in the air, and when the spores of dung-infesting species alight on a mushroom-bed they find a nidus already prepared that exactly suits them ; and if the spawn of the new-comer becomes more profuse than that of the mushroom the stranger takes up his position at the expense of the mushroom. There is also a fungus named Xylaria vaporaria (B. ), which some times fixes itself on mushroom-beds and produces such an enormous quantity of string- like spawn that the entire destruction of the bed results. The spawn is sometimes so profuse that it is pulled out of the beds in enormous masses and carted away in barrows. Sometimes cases of poisoning follow the consumption *of what have really appeared to gardeners to be true bed-mushrooms, and to country folks as small Horse Mushrooms. The case is made more complicated by the fact that these highly-poisonous forms now and then appear upon mushroom-beds to the exclusion of the mush rooms. This dangerous counterfeit is A. fastibilis (Fr. ), or sometimes A. crustuliniformis (Bull.), a close ally if not indeed a mere variety of the first. A description of one will do for both, A. fastibilis being a little the more slender of the two. Both have fleshy caps, whitish, moist, and clammy to the touch ; instead of a pleasant odour, they have a disagreeable one ; the stems are ringless, or nearly so ; and the gills, which are palish clay -brown, distinctly touch and grow on to the solid or pithy stem. These two fungi usually grow in woods, but sometimes in hedges and in shady places in meadows, or even, as has been said, as invaders on mush room-beds. The pale clay - coloured gills, offensive odour, and clammy or even viscid top are decisive characters. A reference to the accompanying illustration (fig. 2), which is about one-half natural size, will give a good idea of A. fastibilis ; the difference in the nature of the attachment of the gills near the stem is seen at R, the absence of a true ring at s, and of a pendent frill at T. The colour, with the exception of the gills, is not unlike that of the mushroom. In determining fungi no single character must be relied upon as con clusive, but all the characters must be taken together. Sometimes a beautiful, somewhat slender, fungus peculiar to stumps in woods is mistaken for the mushroom in A. ccrvinus (Sch.); it has a tall, solid, white, ringless stem and somewhat thin brown cap, furnished