t 75 deg. or 80 deg., they may
be spawned. The beds must be spawned when the temperature falls, never
when it rises. The bricks of spawn are broken into eight or ten pieces,
and these pieces are inserted from one to two inches below the surface,
about nine to twelve inches apart. The bed is then firmly compressed. An
advantage is found in breaking and distributing the spawn over the
surface of the bed a few days before spawning; this allows the mycelium
to absorb some moisture and swell to some extent. If the bed is in
proper condition it should not require watering for several weeks.

[Illustration: Figure 501.--Brick Spawn, Pure Culture.]

=CASING THE BEDS.=--As soon as the spawn is observed to "run," or from
eight days to two weeks, the beds are "cased" or covered with a layer of
about one inch of light garden loam, well screened. The loam should be
slightly moist, and free from organic matter. The beds should now be
watched and should not be allowed to evaporate or dry out.

=PICKING.=--Mushrooms should appear in from five to ten weeks after
spawning, and the period of production of a good bed ranges from two to
four months. In picking the mushrooms an intelligent hand will carefully
twist it from the soil and fill the hole left in the bed with fresh
soil. Pieces of roots or stems should never be allowed to remain in the
beds, otherwise decay might set in and infect the surrounding plants. A
good mushroom bed will yield a crop of from one-half to two pounds per
square foot. Mushrooms should be picked every day or every other day;
they should not be left after the veils begin to break.

For the market the mushrooms are sorted as to size and color, and packed
in one, two or five-pound boxes or baskets. Since they are very
perishable, they must reach the market in the shortest time.

=OLD BEDS.=--It is not practicable to raise another crop of mushrooms in
the material of an old bed, although this material is still valuable for
garden purposes. The old material should be entirely removed, and the
mushroom house thoroughly cleaned before the new beds are made. If this
precaution be omitted the next crop may suffer from the diseases or
enemies of the mushrooms.

[Illustration: Figure 502.--A Cluster of 50 Mushrooms on One Root, Grown
from "Lambert's Pure Culture Spawn" of the American Spawn Co., St. Paul,
Minn.]

=SPAWN.=--The cultivated mushroom is propagated from "spawn," the
commercial name applied to th