As many tons of artificial spawn are yearly imported into this country, it would seem that the manufacture of spawn in the United States might prove a profitable form of investment.

"Brick Spawn."

For commercial purposes the English method of making the spawn into bricks has some advantages over the French "flake" process. Its compact and uniform shape makes the brick more convenient for storage and general handling, and greatly facilitates its transportation to long distances. Brick spawn is made in the following manner: Clean horse droppings, cow manure, loam, and road sweepings are beaten up in a mortar-like consistency and then formed into bricks, moulds being used, slightly differing in shape with different makers, but usually thinner and wider than common building bricks. The following proportions are given: (1) Horse droppings the chief part; one-fourth cow dung; remainder loam. (2) Fresh horse droppings mixed with short litter for the greater part; cow dung, one third; and the rest mould or loam. (3) Horse dung, cow dung, and loam, in equal parts. When about half dry, depressions are made in the bricks, sometimes in the centre, and sometimes in each corner, and small pieces of good spawn are placed in these depressions, and plastered over with the material of the brick. The cakes are then laid out to dry, standing on their edges, and when nearly dry are piled in pairs with the spawn-larded surfaces face to face. The bricks are then stacked away, and covered with sweet fermenting litter, sufficiently to cause a heat of 60° F. It should not be over 70° F. One spawn manufacturer says that the most rapid and successful growth of the mycelium is attained when the temperature is from 63° F. to 67° F. The bricks are examined frequently during the process, and when the mycelium of the old spawn has permeated the whole mass like a fine white mould, the bricks are taken out and dried in a well-ventilated dark place. They are then placed in a cool, dark storehouse, where they are not subject to dampness and where the temperature is about 50° F., not over 65° or below 35° F. Slight ventilation is necessary, but not enough to make the bricks dust-dry. Keeping the spawn dry merely suspends its growth; as soon as it is again submitted to favorable conditions of moisture and heat, its pristine activity returns. Dampness, combined with heat, stimulates the growth of mycelium; frost also destroys the vitality of the spawn. It is evident, therefore, that these conditions should not exist in the store-room.

One manufacturer advocates piling the bricks, after spawning, on a clay floor, packing closely four bricks deep, and covering them with sifted loam. By this method it is claimed that danger of "fire fang" will be avoided, as the bricks will be kept at a perfectly uniform temperature of about 60° or 66°, which causes the spawn to run quickly and uniformly. In from four to six weeks they are ready to take out and dry for use or storage.

The French or "Flake" spawn comes in light masses of loose, dry litter. It is obtained in the following way: A bed is made up as if for mushrooms in the ordinary way, and spawned with "virgin" spawn, and when the bed is thoroughly impregnated with spawn, it is broken up and set aside to dry. This spawn is usually sold in small boxes, containing from two to five pounds, but it also can be obtained in bulk when it is purchased by weight. The French or "flake" spawn is much more expensive than the English or "brick" spawn. It is claimed by some very successful growers, who have tried both, that the brick spawn produces heavier and fleshier mushrooms than the French "flake."

"Mill Track" Spawn.

"Mill track" spawn was formerly considered the best in England, but since horse power has given place to steam power in the mills there is now no further supply of mill track, and it is practically superseded by the "brick" spawn. The real "mill track" is the natural spawn that has spread through the thoroughly amalgamated horse droppings in mill tracks, or the sweepings from mill tracks.

Spawn Produced in a Manure Heap.

During the past year I have made some experiments in the pine and oak woods of Hynesboro' Park, Maryland, with relation to spawn culture, an account of which may prove of interest to students in this line of investigation. Several loads of stable manure and oak-leaf bedding were well mixed and formed into a mound about three feet in height, having a diameter of six feet, and tapering to about four inches in depth at the outer edge. The mass was quite moist and slightly tamped to give it general consistency. It was exposed to the open air, without protection, during the months of September, October, and November. In the meantime, frequent rains occurred. On examination it was found that the rains did not penetrate to a depth of more than four inches. On opening up the centre of the mound, it was observed that the portion thus exposed consisted of highly decomposed leaves, and presented a white mass of matted, "burned" mycelium. It was evident that the temperature at that point had risen considerably above 100° Fahr. The mycelium was, doubtless, produced in abundance before the temperature reached 100 Fahr. and became scorched as the temperature increased. On examining the outer edges, where the depth was only twelve inches, I found an abundance of mycelium which did not show any appearance of having been scorched by undue temperature. Since no mycelium had been added to the mound, it is evident that the spores which produced it must have been present, although unobserved, and awaiting only the proper conditions for development, i. e., for budding and the production of mycelium. At the end of the third month, groups of the common meadow mushroom, Agaricus campestris, together with some fine examples of Tricholoma terreum, an edible mushroom, common to these woods, appeared on the edges of the mound.

APPENDIX A.