==Preparation of the Bed.==—­The manure should come from stables occupied by horses in good health, fed exclusively on hard food.  The most suitable store is the floor of a dry shed, or under some protection which will prevent the loss of vital forces.  Ammonia, for example, is readily dissipated in the atmosphere or washed away by rain.  The manure should neither be allowed to become dust dry, nor to waste its power in premature fermentation.  Operations may be commenced with three or four loads.  A smaller quantity increases the difficulty of maintaining the requisite temperature when fermentation begins to flag.  The first procedure is to make the manure into a high oblong heap well trodden down.  If the stuff be somewhat dry, a sprinkling of water over every layer will be necessary.  In a few days fermentation will make the heap hot all through, and then it must be taken to pieces and remade, putting all the outside portions into the interior, with the object of insuring equal fermentation of the entire bulk.  This process will have to be repeated several times at intervals of three or four days until the manure has not only been fermented but sweetened.  When ready it will be of a dark colour, soft, damp enough to be cohesive under pressure, but not sufficiently damp to part with any of its moisture, and almost odourless; at all events the odour will not be objectionable, but may be suggestive of Mushrooms.  Make a long bed, having a base about four feet wide, and sides sloping to a ridge like the roof of a house, with this difference—­the narrow part of the ridge is useless, and the top should, therefore, be rounded off when about a foot across.  Some growers prefer a circular bed of six or eight feet diameter at the bottom and tapering towards a point, after the shape of a military tent; but here again the point will be worthless, and the bed may terminate abruptly.  Either the long bed or the round heap answers admirably.  Tread the manure down compactly, and for the sake of appearances endeavour to finish it off in a workmanlike manner.  During the first few days there will be a considerable rise in the temperature, which will gradually subside, and when the plunging thermometer shows that it has settled down to a comfortable condition of about 80 deg. the bed must be spawned.  Experienced men can determine by the sense of touch when the temperature is right, but the inexperienced should rely entirely on the thermometer.  The question will arise as to the period of the year when operations should be commenced.  Well, the experts who grow Mushrooms in the open ground for market gather crops almost the year round; but a beginner will do wisely to start under the most favourable natural conditions, and these will be found about midsummer, because the bed will commence bearing before winter creates difficulty as to temperature.