406 PHARMACEUTICAL BOTANY 
fields during late summer and early autumn. It is never found 
in the forest or on trees or fallen trunks, seldom in the mountains. 
The cultivated form grows in specially constructed houses made 
of boards. A corridor runs through these houses so that the 
-mushroom beds can be easily reached. In the growth of mush- 
rooms tons of horse manure are used. This is covered with 
loamy soil 114 inches thick. The whole mass is compacted 
together. Into the resultant beds is introduced English-grown 
spawn, which comes in flat brick-shaped masses (horse manure 
through which mycelium has grown). Pieces of these ‘‘bricks”’ 
ai 
Diseaies = 
-- ey 3 
Fic. 301.—Fruiting surface (hymenium) of a mushroom (Agaricus). m, hyphe 
of the trama and sub-hymenium; 4, basidium; st, sterigma; sp, spores. Diagram- 
matic. (Gager.) 
are put in the horse manure bed only after the heat has first 
disappeared. The beds are then watered well and in a short 
time the sporophores or fruiting bodies of the fungus spring up. 
The mycelium or vegetative body of Agaricus which develops 
in the soil from spores (basidiospores) is white and thready. 
On this mycelium develop little white buttons, first about the 
size of a pin head, becoming later pea size and then assuming a 
pear-shaped form. At this stage the sporophore consists of a 
cylindrical solid stipe or stalk and a pileus or cap. The border 
of the pileus is joined to the stipe by means of a “partial veil.’ 
Within this veil is found a circular cavity, into which the gills | 
grow. At first the stipe grows faster than the rest of the fruiting 
