TAXONOMY 
223 
supinate with pores or shallow depressions on their upper surfaces 
( Merulius ), or mushroom-like {Boletus), or of the nature of woody 
(. Fomes ) or fleshy {Fistulina) brackets. In all cases the hymenium 
or basidial layer lines the inner surface of pores. 
The sporophore of Polyporus officinalis when deprived of its outer 
rind and dried constitutes the official N. F. drug Agaricus. This 
species grows abundantly on various species of pines, spruces and 
larches. 
Family III. — Agaricacese, the gill family, in which the hymenium 
covers blade -like plates of the pileus, called gills, generally occurring 
on the under surface of the same. Examples: Agaricus campeslris, 
the common edible mushroom of fields; Amanita muscaria and 
Amanita phalloides, both of which are poisonous. 
Agaricus Campestris (Common Mushroom). — This plant is an 
edible gill fungus which grows in open, grassy fields during late sum- 
mer 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 mushrooms tons of horse manure are 
used. This is covered with loamy soil 1 Y<i 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” 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 develops little 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.'' 1 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 body. The pileus expands transversely and 
the gills keep pace. After a while the veil ruptures, leaving a portion 
