FUNGI 
AS OS Sexes SaaS. 
WOO RRL OPA 
ne Naeetered 
are not single plants, but 
that each lichen is formed 
of a fungus and an alga 
living together so inti- 
mately as to appear like 
a single plant. In other 
words, a lichen is not an 
individual but a firm of 
two individuals, very un- 
like one another. If a 
lichen be sectioned, the 
relation between the two 
constituent plants may be 
seen (Fig. 156). The fun- 
gus makes the bulk of the 
body with its interwoven 
mycelial threads, in the 
meshes of which lie the 
Algz, sometimes scattered, 
sometimes massed. It is 
Fic. 156.—Cross-section of a lichen, show- 
ing the interwoven mycelium of the 
fungus (m) and the enmeshed alga (g). 
—After Sacus. 
these enmeshed Algwz, showing through the transparent my- 
celium, that give the greenish tint to the lichen. 
Fie. 157.—Section of one of the cup-like bodies of a lichen, showing the stalk of the 
cup (m), the masses of Algz (g), and the lining layer of asci (h).—After Sacus. 
