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now no further supply of mill track, and it is practically superseded by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
w