FUNGI 147 
some that are important. All of them, at some period of 
the life-history, produce spores in sacs, and the sacs are 
usually contained in a spore- 
fruit. The spore-fruit is of three 
general kinds: (1) a hollowsphere, 
completely enclosing the sacs; (2) 
a flask-like structure with a small 
open neck; and (3) a cup-like or 
saucer-like structure which is 
lined by a layer of sacs. 
The first kind of spore-fruit is 
illustrated by the mildews just 
described. It is of interest to i 
know that truffles are such 
closed spore-fruits, having be- 
come large and edible. The 
truffe Fungi are saprophytic, 
the mycelium being found espe- 
cially in forests under decaying 
leaves. The truffles of commerce 
are obtained chiefly from France 
and Italy. 
The sac Fungi with flask-like 
spore-fruits are illustrated by 
many forms growing on dead 
wood or as parasites under the 
bark of trees and shrubs, and 
forming upon the surface of the 
bark black, wart-like growths 
that include the spore-fruits, in 
Fic. 136.—Head of rye attacked 
plum- and cherry-trees produc- by ergot fungus, conspicuous 
: herd k black growths replacing the grains of 
ing the 1S€ase nown as c rye.—After TULASNE. 
knot. An important member of 
this group is the fungus that produces the ergot of medi- 
cine. It is parasitic upon the young heads of rye and 
