MUSHROOMS 411 
perature requirements are rather exacting. Special 
piping is necessary in mushroom houses in order to main- 
tain sufficient heat. 
Material for beds.—Various kinds of organic materials 
have been used 
for the growing 
of mushrooms. 
but there seems 
to be a consen- 
sus of opinion 
that fresh horse 
manure gives 
the best results. 
Most growers 
prefer that it 
contain consid- 
erable straw, al- 
though good re- 
sults are some- 
times obtained 
from manure 
with a small 
proportion — of 
bedding. If saw- 
dust or shav- 
ings have been 
used for litter, more time will be required to effect proper 
fermentation, and it is likely that such manure does not give 
as uniformly good results as strawy manure. The French 
growers prefer manure from grain-fed animals bedded 
with rye straw. Any of the cereals grown in America 
used for bedding grain-fed animals will produce manure 
which is entirely satisfactory for the growing of mush- 
rooms. It is desirable that the manure be fairly open 
and porous after it has fermented, and the cereal straws 
seem to bring about this condition. The large commer- 
Fig. 150.—Mushroom beds in a modern house. 
