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Mushrooms

The popular name given to a group of Fungi, very numerous in species, but with a strong family likeness, which renders them easily recognisable, as will be seen from the subjoined figures (Figs. 610 and 611). In a limited sense, the name is often used to denote certain edible Fungi; but, in a wider sense, it includes many useless and poisonous kinds, such as Toadstools, the Fly Agaric, and numerous others belonging to the genus Agaricus, as well as to certain allied genera, viz., Boletus, Cortinarius, Hydnum, Lactarius, &c.; and it is even used occasionally, but incorrectly, to denote all Fungi. Excluding this last sense, the Mushrooms, in their commonly-known condition, are only the spore-bearing parts of the plants, and arise from a dense network of filaments (mycelium) buried in soil containing decaying matter, or in the wood of dying or dead trees. These spore-bearers generally resemble a cap (pileus), supported on a stalk, which is fixed to the lower surface of the cap in the middle, or, less frequently, to one side of it. The cap may vary from 1/2in. to about 1ft. across, and the stalk also varies much in length and in thickness. On the lower surface of the cap is spread the hymenium, or surface on which the spores are formed. These are fixed to short, slender stalks, of which four stand on the free end of each of certain large cells (basidia), which are scattered over the hymenium. The latter varies much in the mode of attachment to the cap, and in the degree and modes of folding that it undergoes. The genera and species nearly related to the true Mushrooms have it easily separable from the tissue of the cap; but Polyporus, and certain allied forms have it closely grown to the latter. The surface over which the hymenium is spread, is very much increased, in most of the genera, by being folded in various ways.

In Agaricus, the genus to which the great majority of Mushrooms belong, the lower surface of the cap bears numerous thin plates (gills), hanging downwards, and radiating from the stalk to the circumference; and on the sides of these the spores are formed. The gills may be continued unbroken into the stem, or may be separated from it by a narrow space. This difference in the gills, the varied colours of the spores, and the presence or absence of the veil--a membrane passing, in the young Mushroom, from the edge of the cap to a ring round the stalk--are all important characters in determining the genus and species of Mushroom under examination. In Hydnum, the hymenium is scattered over fleshy, tapering outgrowths, or teeth, on the lower surface of the cap; in Boletus and Polyporus, the surface is formed by reticulately-joined ridges, that leave tubes, or pores, between them; in Craterellus, it is smooth, or merely wrinkled. Mushrooms vary exceedingly in colour, the upper surface of the cap usually showing more decided tints than the stalk. Many are white; others yellow; others red in various tints; others show shades of grey or brown, at times almost passing into black. A smaller proportion are some shade of blue. or of metallic green; but they do not show a pure leafgreen, dependent on the presence of chlorophyll, since they never contain this substance. The surface of the cap is usually smooth; it may be sticky, hairy, warty, &c. Some species change colour, at once or gradually, if any part is broken. This is peculiarly noticeable in some kinds of Boletus, in which the bruised surfaces become an intense blue. The change to blue is to be regarded as a sign that the Mushrooms which show it are poisonous or suspicious in their properties. The smell of Mushrooms is slightly peculiar, and is usually not difficult to recognise, there being in it something that reminds one of a closed, mouldy vault or cellar. In decay, most of them emit a strong nitrous smell, some have a most disagreeably foetid stench, but others are rather pleasantly scented, like newly dried hay. A curious property of some Fungi is the luminosity they display. In some kinds, the light is so strong that, in dark places, the plants can be seen from a considerable distance. This phenomenon is manifested by species in various groups of Fungi; but the most striking examples are met with in the genus Agaricus, several members of which have been observed to be luminous, apparently in the healthy state. In some, the cap and stalk emit light; but more frequently the mycelium in decaying wood is the luminous part. Another characteristic of some Mushrooms--e.g., the genus Lactarius and several species of Agaricus--is the appearance, on broken or cut surfaces, of a milky fluid--the latex--which pours out from long tubular cells in the tissues of the plant. This fluid may be white, yellow, or orange; and, at times, changes colour after being exposed to the air for a short time. In some cases, the latex has a pleasant taste, while, in others, it is very acrid. Mushrooms, like Fungi in general, are propagated by means of spores, which, as already mentioned, are borne on large cells (basidia), produced on the hymenium. These spores can be obtained by laying the Mushrooms, gills downwards, on paper, which should be of a tint to contrast with them in colour. They will be found to map out on the paper the arrangements of gills or pores, and, in this way, their colour in mass also can be easily detected. The colour of the spores is largely employed in breaking up the very large genus Agaricus into sub-genera of more convenient size.

Uses. Mushrooms and their allies include almost all the Fungi that can be regarded as of direct use to man as food-plants. A considerable number have been, or are, used in diet, either because of the amount of nitrogenous matter in them, or as imparting a pleasant flavour to the articles, with which they are served at table. But, while it is comparatively easy to recognise certain of the well-known edible Mushrooms, great care is required to prevent serious results when poisonous species are gathered by mistake, and eaten with the useful ones. Such a mistake is not infrequent, since a very great resemblance exists between certain poisonous and edible kinds. The Mushroom most generally esteemed in Britain is the Common Mushroom (Agaricus campestris), It is so well known as scarcely to call for a detailed description of its appearance. It is largely cultivated, but it is also frequently abundant in pastures, especially in natural grass land or meadows. At first, the gills are pale pink, or salmon-tinted, but they deepen into a peculiar purplish-brown. The upper surface of the cap varies somewhat in colour and smoothness, and there is a permanent ring of tissue around the stem, a little way below the cap. This Mushroom does not enjoy the same high reputation on the Continent of Europe that it possesses among ourselves; and, in Italy, it is said to be regarded by the labouring classes as even poisonous, or, at least, suspicious. A nearly allied kind, the Meadow or Horse Mushroom (A. arvensis), is considerably larger than the last, and grows in similar localities; but its cap is pure white on the top while young, and it has paler gills than A. campestris. It is often gathered in large quantities for sale, but is somewhat less delicate than the Common Mushroom in its flavour. These are most abundant in autumn, but the St. George's Mushroom (A. gambosus,), a large species, appears in spring. For this reason, and because of its flavour, it is much esteemed, and fetches a high price. The cap is nearly white, the gills are pale yellowish, and there is no ring on the stalk. It can be dried so as to retain its characteristic flavour. It smells strongly of new meal. Numerous other species of the genus Agaricus are recognised in Britain as edible. Several of these are more abundant in woods than in open places, despite the general rule that Fungi from such localities are more open to suspicion. From among these useful Agarics we may enumerate the following, which, for the most part, are less generally known than are the preceding; and which are somewhat dangerous to use, from their resemblance to certain kinds which are often to be found in similar localities: A. fragrans and A. odorus, both with a scent like aniseed; A. maximus, white, may reach 14in. in breadth of cap; A. ostreatus and A. ulmarius, found on Elm trunks, both with stalk attached to one side of the cap; and A. prunulus, a white Mushroom, with a smell like meal, found growing in woods. Berkeley, in his "Cryptogamic Botany," p. 367, says that at least a tenth of the species of Agaricus are esculent. Other Mushrooms belonging to genera nearly allied to Agaricus are scarcely, if at al, inferior to its species in their value as food-plants for man; nor would the generic differences between them and Agaricus strike anyone not a botanist as of much importance. The more valuable of these edible forms are Marasmius oreades (see Marasmius) and Coprinus comatus. The latter is esteemed while the gills are still whitish or reddish in colour, but it soon becomes soft, and deliquesces into an inky fluid; it is common in pastures and other open places. Several species of Cortinarius (a genus with rust-coloured spores and a web-like veil) are also edible. All of them inhabit woods. Among them may be noted C. violaceus and C. cinnamomeus, characterised by their colours, to which they owe their specific names. In the genus Lactarius, notable because of the milky juice that its species contain, several are dangerous and acrid; but others are esculent, their juice being mild and pleasant in flavour. The quality of L. deliciosus is sufficiently indicated by its name. This Mushroom is an exception to the rule that change of colour in broken parts is to be regarded as a sign of poisonous properties, since the milk in it, when fresh, is saffron-coloured, but, when exposed to the air, becomes dull green. The genus Russula also includes both poisonous and edible species, but need not be dwelt on here, as the latter are not largely used.

Cantharellus cibarius, or the Chantarelle, is one of the best of edible Mushrooms. See Chantarelle. Very similar in appearance to the gill-bearing Fungi are many of those in which the gills are replaced by teeth, as in Hydnum (see Hydnum), or are united, so as to leave between them tubes or pores, as in Boletus, Fistulina, and Polyporus, and these are usually included among Mushrooms. Boletus includes numerous kinds, much like Agarics, but the lower surface of the cap shows very numerous pores. B. edulis is sold in many parts of the Continent of Europe, cut into thin slices, or hung on strings and dried. It is little esteemed in England. B. aestivalis, which appears in early summer, is said to be of excellent flavour. Various other species of Boletus have been recommended as of fair quality, such as B. aureus, B. aurantiacus, &c.; while others, on the contrary, are dangerous.

Polyporus is a very large genus, the species almost all growing from dying or dead wood, and being attached to the stalk by one side. The spore-bearing surface is usually below. The species vary much in texture, between fleshy and woody. Several may be said to be edible, but cannot be highly recommended.

Fistulina hepatica, or the Beef-steak Fungus, like the last, grows on trees, usually Oak, and is much like Polyporus in structure, but is juicy. The popular name is derived from the great resemblance to a piece of beef-steak. Its weight may exceed 20lb. It is used sliced and eaten with salad, or like true Mushrooms, and is much esteemed as an article of diet. Catsup, or Ketchup, made from the juice of many kinds, is also a valuable product of the group.

INJURIOUS PROPERTIES OF MUSHROOMS. Some of the evils attending the use of these plants must be mentioned here. Among the more serious are the poisonous effects produced when many of them are used as food, these effects varying, according to the nature of the Fungus, from mere nausea to very serious symptoms, or even death. Many of the poisonous species are so similar to edible ones, that the only safe rule to follow is to make oneself thoroughly familiar with the latter, or, at least, with a few of them; and to use these alone rather than to risk the consequences of using poisonous kinds by mistake. Rules have frequently been given whereby poisonous and edible Mushrooms respectively may be recognised, such as that those should be avoided, or, at least, used with great caution, that grow on wood, or have a strong, disagreeable smell, or acrid taste, or turn blue when broken, or are bright red in colour, or have pink spores; but all such rules err by admitting hurtful, or excluding useful, kinds, and only familiarity with the individual species can be safely relied on as a guide as to what to use. But even edible Mushrooms may become injurious if kept too long before being eaten; hence, they should be used only when fresh, except in the case of the few, like Marasmius oreades, that can be dried and preserved for future use. Any suspicious kinds should be cooked for a long time with abundance of salt and vinegar, as the poisonous properties are frequently removed by this treatment. Among the most poisonous of the commoner Mushrooms is Agaricus (Amanita) muscarius, or the Fly Agaric, a large Mushroom, with a red cap, studded over with pale warts common in woods in Britain. This plants, if eaten, even in small amounts, causes headache, nausea, and delirium, and often convulsions, followed by stupor; and the urine of those who have eaten it, when swallowed, produces the same effects. It is occasionally used as a fly poison, whence its name. Russula emetica, with smooth red cap and white gills, also found in woods, is very poisonous, giving rise to vomiting and purging. Many others, more or less virulent, might be dwelt upon, did space allow. But, besides directly bad effects, many Mushrooms are scarcely less hurtful indirectly, by the evil they do to trees and other plants, unless, indeed, we suppose the fungi to follow, not to cause, disease. From this point of view, Agaricus melleus is probably the most hurtful of the true, or gill-bearing, Mushrooms. It grows usually in dead or dying wood, but it also attacks cut or bruised surfaces, and from these its mycelium extends to the healthy wood, and soon causes the latter to decay. Very frequently, the mycelium forms black root-like bodies, running between the wood and the bark of the tree, emitting short branches at right angles to the larger ones. It is peculiarly injurious to conifers, and seems to be almost cosmopolitan in temperate zones. Its evil properties may be regarded as slightly compensated by its being edible, though not highly esteemed because of its acrid, disagreeable taste. The stalk is yellowish, with a blackish tinge at the base, 3in. or 4in. long, at last becoming hollow, and near the top bearing a complete annulus. The cap is yellow-brown (or may show a greenish tinge), with the centre darker, and bears scattered brown scales. The gills are white or yellowish, and are broad but unequal. The cap has a peculiar earthy aspect. The pore-bearing Fungi are yet more hurtful than Agarics, and several species of Polyporus may be enumerated that are markedly injurious to trees. Observations upon their powers of doing harm have been made far more completely in Germany than in our native forests. Space will permit here of little more than an enumeration of some of the more generally distributed of the hurtful kinds, e.g., P. sulphureus, on Oak, Willow, Larch, &c.; P. dryadeus, on Oak; P. betulinus, on Birch; P. igniarius, on Poplars, Willows, Ash, Cherry, &c.; and P. vaporarius, on conifers. The nearly allied Trametes Pini and T. radiciperda are very fatal at times to Pines on the Continent; and Fistulina hepatica causes the decay of Oak. Wood prepared or made use of for building houses or ships is also liable to injury unless thoroughly seasoned and kept in a dry place; and Dryrot is but too familiar to many a householder, because of the rapid decay induced by the mycelium of Fungi, by which the wood is brought into a powdery, rotten state. The species that generally bring about this condition are Merulius lacrymans (which see), Polyporus hybridus, and P. vaporarius; but others also are known to be destructive.

Remedies. Upon the nature of the injuries done by Fungi, the remedies must, of course, depend. To avoid evil effects from the use of Mushrooms as food, great care must be exercised to insure that only edible kinds shall be gathered and made use of. Long exposure to heat in cooking, combined with the free use of salt and of vinegar, has been found to remove the poisonous properties of many species, but not of all. Should evil results follow the use of Mushrooms in food, the readiest means for the removal of the food by emetics and purgatives should be resorted to, and a doctor should be summoned without delay. It is hardly possible to prevent the death of trees attacked by such Fungi as Agaricus melleus or Polyporus squamosus, since the wood is full of their mycelium. Unless the trees are of very peculiar value, it is better to destroy them at once, in order to prevent the Fungus spreading to other trees. Prevention is far better than cure, and more regard must be paid to the preservation of those still sound than to keeping the diseased one. Young trees should never be planted in soil in which there are decaying pieces of wood. For the treatment of Dry-rot, see Merulius lacrymans. A few words may be added upon the geographical distribution of Mushrooms. Many of them are known to be almost cosmopolitan, or to be distributed in countries very wide apart; while others are, as yet, known to occur only in very limited areas, probably because of the small number of workers in this group of plants leaving our information regarding them very incomplete. The genus Agaricus is more abundant, and its species are more fleshy, in temperate than in tropical latitudes. On the contrary, Polypori are more numerous and striking in tropical regions. In temperate climates, Mushrooms are most numerous in autumn; but, in tropical countries, they appear all the year round. In respect to habitat, Mushrooms may be met with in all situations where decaying or dying plants occur, or where the soil is full of organic matter. Hence, they are most abundant in forests, on the soil, and on dead or dying trees; and some species prefer woods composed of certain kinds of trees-thus, forests of Firs and other conifers are particularly rich in Mushrooms. Agaricus affords examples of preferences of all kinds, some even growing on dead plants of other species of this genus, others in open places, but most in woods. The sub-genera usually show a preference for some one kind of habitat, e.g., Amanita and Collybia prefer woods; Lepiota and Psalliota, open places; Omphalia, swamps; and so forth. Cantharellus prefers grassy spots in woods; Coprinus, the neighbourhood of mankind; Hygrophorus, open places, such as meadows and moorlands, even high on the sides of mountains; Hydnum, the shade of woods; Russula, soil in open places in woods. Polypori are almost confined to woods, or to dead logs.

Mushrooms preserve badly as fossils; hence, comparatively little is known of them in this state, though a few, e.g., Polyporus lucidus, have been found semi-fossilised in the later formations.

CULTIVATION. The cultivation of the common Mushroom (Agaricus campestris) is invariably work of great importance in gardens, a supply being generally expected from those wherein the means of cultivation are at command. Conditions requisite for securing good crops seem, in many instances, to be of an exact description, while, in others, excellent results are attained when only ordinary attention is bestowed in preparation. This may partly be attributable to the seasons, natural temperatures, and other matters being favourable or otherwise to Fungus growth. Gardeners experienced in Mushroom culture, know with tolerable certainty, how a bed is likely to succeed from the time it is made up and spawned; but there are many cultivators, noted, maybe, for their success in other departments, who, from one reason or another, frequently fail to secure satisfactory results from their efforts devoted to Mushroom culture. There are various causes to which failure may be attributed, if any of the numerous details in cultivation are improperly executed. Attention from the first in the preparation of manure, is one of the most essential points; then, its condition when made into a bed, respecting the temperature likely to be reached by fermentation; afterwards, and last, but not least-to omit a special reference to minor matters-the quality of the spawn. Mushrooms are far more extensively grown, for various reasons, in winter and spring, than they are in summer time, the produce being then in great demand, and no supply obtainable from the open air, as in the latter part of summer and in autumn. A cool temperature, also, is more suitable to their growth, in the later stages, at least, and this is only with difficulty obtained in summer, except by those fortunate enough to possess a house or cellar below the ground level for devoting to Mushroom culture. The spawn requires a somewhat high temperature at first to cause its diffusion to all parts of the bed, and then a much cooler one throughout the later stages of development into the Mushroom as it is used. This is well shown by the appearance of the crop naturally in greater abundance outside when the temperature of both the earth and air are on the decline, and the ground is well moistened by early autumn rains.

Preparation of Manure. Manure from stables in which carriage horses are kept, is usually procurable for Mushroom culture, and, as a rule, none could be better suited for the purpose. It should be collected each morning, if possible, laid separate from the litter in a covered shed, with an open front. Here it must be frequently turned, to prevent overheating, and to allow of the escape of rank steam. When enough is accumulated to make a bed of the desired size, it should be kept separate from any that is freshly obtained, the latter being put into another heap, and, in turn, similarly treated. Each or every alternate morning, the heap first referred to must be turned and well shaken apart, until rank steam is no longer present, and the manure is just sufficiently moist to hold together when squeezed. The time thus taken in preparation varies considerably according to the prevalence of a dry or moisture-laden atmosphere. Some cultivators of Mushrooms prefer a portion of litter mixed with the manure, while others do not. The chief difference is the effect it has when the beds are being made, in preventing the mass from being rammed too firmly. The degree of firmness often affects the period over which the crop is produced, by shortening or lengthening it in proportion. This will be further referred to; and as good results have been obtained both with and without litter intermixed, the matter is not one of material importance. Formation of Beds, Spawning, &c. The manure, having been thoroughly prepared, as above described, should be made up at once into a bed, a suitable depth for this being 9in. in front and about 12in. at the back, if against a wall. The size in other directions must be regulated by the amount of manure available and other circumstances. When a supply of Mushrooms is required in the shortest possible time, the manure should be merely well trodden, to render it firm, but otherwise it should be rammed hard throughout with a brick or hand-rammer. It is not advisable to introduce the spawn at once, as its vitality may be destroyed if the bed should become over-heated. The highest temperature here recommended at which spawning may be practised with safety, is 90deg., and it should be known for certain that the heat is, at the time, gradually receding below that point. Small pieces of spawn should be inserted in holes made with a trowel, about 4in. apart, the manure so removed being used for covering it over. In about a week afterwards, or sometimes earlier, 1in. to 2in. of moist, rather heavy loam, free, if possible, from sand, which is very injurious, should be laid all over the surface, and beaten hard with the back of a spade. The tiny Mushrooms seldom appear in less than four or five weeks front spawning, and the time during which the beds remain productive afterwards varies very considerably. Mushrooms are often more in demand for various dishes when about half than when fully developed. In this stage, represented in Fig. 614, they are called "buttons," the single specimen shown being, however, that of an older one. No more should be cut when at this size than is really necessary, as it is obvious that the crop would be enlarged considerably by allowing a few days' more growth. A successional bed should be ready for spawning by the time the previous one begins bearing. Opinions differ respecting the watering of Mushroom beds. It is tolerably certain that watering frequently proves very injurious, and should be avoided as much as possible; yet it is difficult to keep the surface sufficiently moist when fire-heat becomes a necessity. Sometimes, when beds have become very dry, a good watering has caused a heavy crop to spring up; consequently, it is not always an injurious practice. The walls of the Mushrooms house should be frequently syringed, and the floor always kept moist, especially when the use of fire-heat is necessary.

Outside Culture. Growers of Mushrooms on a large scale for market, pursue a different system altogether from that just described, by forming their beds in ridges outside. These ridges are made on a hard piece of ground, and are about 3ft. wide at the base, the two sides sloping somewhat steeply to the top. The manure is collected from stables, and turned a few times, but it does not receive so much preparation as is recommended above for indoor beds. It is well trodden, and the sides are beaten hard into shape. After spawning, the whole surface is covered with about 2in. of adhesive loam, which is usually watered, and then beaten with the back of a spade. A covering of litter or long straw, varying in thickness according to the temperature of the bed, is kept over the whole, as shown in the illustration, to ward off storms, and preserve, as near as possible, a uniform temperature underneath. It is obvious that this system involves a considerable amount of labour not required with beds inside, in covering and uncovering for every purpose, yet it is practised most successfully and very extensively by growers for market. Another plan, which may be useful for growing Mushrooms in outside beds, and affording them protection in winter, is shown in Fig. 616. Any sort of frame-work might be roughly constructed above the bed on which to place mats or other covering, and a cord run over to fasten them on. Straw screens or thatched hurdles, are excellent movable coverings, and, being non-conducting, they are well suited for preserving an equable temperature, where the admission of light is not necessary. A crop of Mushrooms is frequently found growing naturally outside in places where they are least expected, and such produce is considered superior to that obtained under artificial cultivation. The insertion of some spawn in an old melon bed, in the ordinary turf of a lawn, or in a small quantity of manure in any old cool frame, are also methods, at times, successfully practised with but little trouble in the summer and autumn. Preparation of Spawn. What would be more correctly termed mycelium, is usually, in the case of the common Mushroom, called spawn. It is a dense, white, fibrous substance, found in quantity amongst old hotbeds, and in places where cattle are kept, these situations being most suitable for encouraging its growth. A dormant vitality is retained by this spawn for a very long time, if kept quite dry; consequently, the soil or manure containing it may be collected in a loose state, and scattered on beds artificially prepared, at any time. A plan which is, however, preferable to this, and the one most generally adopted, is the preparation of spawn in what are called bricks, from their resemblance in shape to flat bricks. These may be purchased from nurserymen, ready for use, at any season, about sixteen being considered equal to a bushel. Extensive cultivators sometimes prepare their own brick spawn; but only a very few, compared with the number who purchase it. One of the modes of preparation is briefly as follows: Fresh horse-droppings are collected and mixed with cow-dung, some using an equal proportion of each ingredient, and some a less quantity of the former, and a little adhesive loam is added to hold the other constituents together. The whole is mixed with liquid stable manure, until as soft as mortar, when it is spread on the floor of an open shed, until sufficiently dried to form into bricks of the shape and size desired. These should be set on edge, turned frequently, and allowed to get about half-dry. Then a hole, about 1in. square, should be made in one side of the brick, near the centre, and filled with good spawn, inclosing it with a little of a similar substance to that of which the bricks were made. Prepare a bed of fresh horse-dung, about 9in. thick, on a dry bottom; build the bricks in a pile above it, allowing a space between each two, and cover with litter, so as to retain a temperature underneath of, as near as possible, 60deg. Under such conditions, the spawn will spread itself throughout the whole of each brick, and the latter must be frequently examined and removed when they are permeated with a white cloudy substance, not so far advanced as to show minute threads. Good bricks of spawn should be in this condition when purchased; otherwise, any part which is too far advanced, or, on the other hand, not properly permeated with mycelium, will be useless. When removed from the hotbed, the drying process should be completed thoroughly, and the bricks stored in a cool, dry place, to arrest any further vegetation, until required for use. Other systems of preparing bricks spawn are practised, differing mainly in details concerning the proportion of the different substances which it is advisable to use in the preparation and formation of the bricks. Mushroom Houses. A Mushroom house may either be a span-roofed structure, or one with a lean-to roof against the back of a high wall. It should be situated as much as possible in the shade, in order that the internal temperatures may not be subjected to so much fluctuation, by reason of the sun shining on the roof. Hot-water pipes should be provided for maintaining the proper temperature in winter; but fire-heat is best done without as much as possible. The interior space may be fitted up for beds according to its size and shape, by having them on one or both sides against the walls, and a path down the centre; or, the beds placed above each other in the middle, and a path allowed all round, a plan sometimes adopted in span-roofed houses In Fig. 619 a section of lean-to Mushroom house is represented, where provision is made for placing three beds one above the other. Two are usually enough in a house of any shape, unless it is very lofty, as a greater space is then available for making up and ramming each bed separately.

No light is necessary for the Mushrooms; but provision should be made for admitting it, to see how to work, and darkened shutters may be placed against the windows at other times. The temperature should be kept as near as possible at 50deg., to suit the beds that are bearing; the heat of other beds may be regulated by coverings of litter, or by movable shutters made to rest on fixed ledges 3in. above the surface, so as to inclose the bed and retain its heat. Mushrooms are sometimes successfully grown on a small scale in tubs or in large pots, as shown in Fig. 620, where A represents the loam on the surface, B the place for inserting some spawn, which would, however, be much better distributed in small pieces, and C the prepared manure. Good results are not unfrequently obtained by this method; but it is not worth practising where a more extensive plan can be adopted.