The French often cultivate mushrooms in cellars as well as in the caves described in the next chapter. Preference should be given to a dry warm cellar; it should be as dark as possible, and exposed to no draughts. Beds can be made in cellars in many ways. Those made in the middle should always be formed with two sides, while those against the walls should only be half as thick, on account of their having only one useful side. It is also possible to arrange them on shelves, one above the other. For this purpose strong bars of iron are driven into the walls, upon which are placed shelves of the proper size covered with earth, upon which is formed a bed, that is treated exactly as those made upon the ground. These beds are just as productive as any of the other kinds. They may even be made on the bottoms of casks, which should be at least two feet six in diameter; and they are built up in the shape of a sugarloaf, about three feet in height, and the pieces of spawn are placed an inch and a quarter deep, and sixteen inches apart. A barrel is sawn crossways into two pieces, each forming a tub. Holes are made in the bottom of each, and a thin layer of good soil is spread over them inside. They are then filled with good well-prepared stable manure, just like that used in the case of ordinary mushroom-beds, the different layers of dung in each tub being well pressed down. When the tub is half full, six or seven good pieces of spawn are placed on the surface, and the remainder is piled up with manure, which is well pressed down, the operation being completed by giving to the heap the form of a dome. The tubs thus prepared are placed in a perfectly dark part of a cellar, and eight or ten days afterwards the dung is taken up until the spawn is visible, in order to see whether it has commenced to vegetate and develop little filaments. If the spawn has spread, the surface must be covered with soil, care being taken to use only that which is fresh and properly prepared. In this or any like way there should be no difficulty in growing mushrooms: the boxes or tubs could be filled anywhere, and then carried into the spare cellars, &c. In this way objections against steaming manure might in many cases be got over. [Illustration: Fig. 16. Pyramidal mushroom-bed on floor of cellar.] [Illustration: Fig. 17. Mushrooms grown in bottom of old cask.]