192 
CLASS CETPTOGA-MIA. 
Fig. 163. 
in texture, form, and color ; they are leathery, woody, leaf-like, 
white, yellow, green, and black ; they are seen on stones, old 
fences, and buildings ; some with strong, green filaments are 
suspended from branches of trees, and improperly called mosses. 
The fruit of the Lichen consists of cups or shields called apothe- 
cia, in which the seeds are contained. Fig. 163, represents a 
lichen of a leaf- 
like appearance ; 
here the apothe- 
cia, imbedded in 
the thallus^ are 
very apparent. 
J is a lichen re- 
sembling a d rink- 
ing-glass. <?isthe 
reindeer moss, 
furnishing al- 
most the solefood 
of that animal, so important to the Laplander. In the middle 
of Europe this lichen grows only to the hight of two or three 
inches ; but in Lapland it sometimes attains to the hight of one 
or two feet. Litmus^ which is so common as a chemical test for 
acids and alkalies, is obtained from a species of white lichen, 
called arcMl / this is also used for giving a crimson color to 
wool and silk. The powder called cudbear^ used for dyeing 
purple, is obtained from a lichen. 
290. Fvm,g% the sixth Order^ contains the Mushrooms^ or 
fungus plants ; these exhibit no appearance of green herbage ; 
they are generally corky, fleshy, or mold-like. The fruit of 
,gome is external, of others internal. They are often of very 
quick growth and short duration. The genus Agarious^ which 
contains the common eatable mushroom, has a convex, scaly, 
white head, called apilei^s ; this is supported on a stalk called 
a stipe. On the under surface of the pileus, or cup, are seen 
many flesh-colored membranes called gills / these in the young 
state of the mushroom, are concealed by a wrapper called 
a volva^ which is considered as a kind of calyx. As the mush- 
room becomes mature, the volva bursts and remains upon the 
stipe, while the pileus released from its confinement extends 
upward and exhibits an uneven appearance upon its edge, 
caused by its separation from the volva. Fig. 164 represents 
at a the gills running from the stipe to the circumference under 
the pileus ; 5, a young mushroom with the pileus of a globular 
form and not separated from the volva ; (?, the volva., or wrap- 
per bursting and separating from the pileus so as to exhibit 
Uses of Lichens.— 290. Fungi or Mushrooms. 
