that mushrooms will not thrive in beds in
which old manure abounds, either in the loam or fermenting material;
that it kills the mycelium. This, too, I must refute. I have seen heavy
crops of spontaneous mushrooms come up in violet and carnation beds in
winter, and where the soil consisted of at least one-fourth of rotted
manure well mixed with the earth. In cucumber and lettuce beds the same
thing has taken place. And in similar beds that have been planted
artificially with spawn, good crops of mushrooms have also been raised,
and the mycelium, instead of evading the lumps of old manure in the soil
often forms a white web right through them.

CHAPTER XIII.

EARTHING OVER THE BEDS.

This is an important operation in mushroom-growing, and the one for
which loam is indispensable. It consists in covering the manure beds,
after they have been spawned, with a coating, or casing as it is more
commonly called, of loam. The spawn spreads in the manure and rises up
into the casing, where most of the young mushrooms develop, and all find
a firm foothold. The loam also contributes to their sustenance. And it
protects the manure, hence the spawn, from sudden fluctuations of
temperature, and preserves it from undue wetting or drying.

The best soil to use for this purpose is rich, fibrous, mellow loam,
such as is described, page 100.

If the manure is fresh and in good condition and the beds are in a snug
cellar or closed mushroom house, I would not case them until the second
week after spawning, say about the eighth or tenth day; but were these
same beds in an open, airy shed or other building I would case them over
some days earlier, say the fourth or fifth day. A fear is often
expressed that when beds are cased within three or four days after being
spawned the close exclusion of the manure from the air is apt to raise
the heat of the manure in the bed, and thereby destroy the spawn; but I
have never known of any truth in this theory, and with well-prepared
manure I am satisfied no brisk reheating takes place, at least the
thermometer does not indicate it. The great danger of early casing is in
killing the spawn by burying it too deep in damp material and before it
has begun to run through the manure.

I have conducted several experiments in order to satisfy myself
regarding when is the proper time to case the beds, and have found no
difference in results between beds that were cased over as soon as they
were spawne