274 CLASS CRYPTOGAMIA. 



following delineation. Fig. 131, a, represents, a lichen of a 

 Fig. 131. 



leaf-like appearance ; here the saucer-like bodies in which the 

 leaves are imbedded are very apparent. b, is a lichen resem- 

 bling a drinking glass, c, is the rein-deer moss, furnishing 

 almost the sole food of that useful animal, so important to the 

 existence of the Laplander. In the middle of Europe it grows 

 only to the height of two or three inches ; but in Lapland it 

 sometimes attains to the height of one foot and a half. 



Many of the lichens are useful on account of their colouring 

 matter. Litmus, which is so common as a chemical test for 

 acids and alkalies, is obtained from a species of white lichen, 

 called Orchal or Archil, this is also used for giving a crimson 

 colour to wool and silk ; and the powder called cudbear, used 

 for dyeing purple, is obtained from lichen. The order Lichen 

 has sometimes been included under one genus called lichen, 

 and placed in the order Alga. 



Fungi, or MUSHHOOMS. 



The 6th order contains the Mushrooms, or fungus plants ; 

 these never exhibit any appearance of green herbage ; they aro 

 generally corky, fleshy, or mould-like, varying much in form 

 and colour. The fruit of some is external, of others internal. 

 They are often of very quick growth and short duration, henco 

 the expression which is often ironically made, " a character of 

 mushroom growth," when a person has suddenly acquired 

 consequence. The genus Agaricus, which contains the com- 

 mon eatable mushroom, has a convex, scaly, white head, called 

 a pileus ; this is supported on a stalk called a stipe. On the 

 under surface of the pileus or cup, are seen many flesh-colour- 

 ed membranes called gills. These gills in the young state of 

 the mushroom, are concealed by a wrapper called a volva, 



Explain Fig. 131 Uses of the lichens Order Mushrooms. 



