If allowed to go further than the fine white mould stage, and form threads and tubercles in the bricks, it has then attained to a higher degree of development than is consistent with preserving its vegetative powers, and therefore it should be removed from the bed in the fine mould stage. This is the kind of mushroom spawn mostly in use in our gardens, and it is usually very hard in texture. [Illustration: Fig. 12. Mill-track mushroom-spawn.] There is a kind of spawn used in some gardens called mill-track mushroom-spawn, which is made in a more simple manner than the preceding. It would seem to be simply spawn that has spread through the thoroughly amalgamated droppings of a mill-track. The material is rather soft and free in texture, is usually sold in large and somewhat irregular lumps, and is much used by some cultivators. [Illustration: Fig. 13. Parisian mushroom-spawn.] Finally, we have the French mushroom-spawn, which differs from our own in not being in bricks or solid lumps, but in rather light masses of scarcely half decomposed, comparatively loose and dry litter. This spawn is obtained by preparing a little bed as if for mushrooms in the ordinary way, and spawning it with morsels of virgin spawn, if that is obtainable; and then when the spawn has spread through it, the bed is broken up and used for spawning beds in the caves, or dried and preserved for sale. It is sold in small boxes, and is fit for insertion when pulled in rather thin pieces, about half the size of the open hand; but in separating it, it divides into many pieces, of all sizes, every particle of which should be used. The small particles should be strewn broadcast over the bed after the larger pieces have been inserted. This applies to the other kinds. In consequence of the open porous nature of the French mushroom-spawn, it is likely to be immediately affected by the heat and moisture of the genially warm manure forming the mushroom-bed, and on that account alone presents some advantages. It has recently been introduced for the first time, and probably will soon be tested by many growers. Spawn, in the common sense of the word, may be dispensed with by well amalgamating manure, loam, and old mushroom-beds, or leaf-mould containing traces of spawn, and these formed into beds about a foot thick in the mushroom-house, and covered with earth, produce without any further spawning; but the plan is not so simple or advantageous as that more commonly pursued. There is no necessity for purchasing artificial spawn at all where mushrooms are regularly grown. Nor is there in any case except at the commencement, or to guard against one’s own spawn proving bad. To secure good spawn, we have only to do as the French growers do: take a portion of a bed where it is thoroughly permeated by the spawn and before it begins to bear, and preserve it for future use.