OF PUFF-BALLS 
9 
enclosed in a cell known as the ascus. Usually, as shown in 
the accompanying woodcut, each basidium bears four spores, 
and each ascus contains eight spores, but 
there are many exceptions to the rule. 
The Basidiomycetes are divided into two 
very distinct sub-orders—the Gasteromy- 
cetes and the Hymenomycetes. In the 
former the spores are developed within the 
outer rind or integument of the plant; in the 
latter they are exposed from the first, or in 
a very early stage. 
The course of development of some 
typical examples of these primary groups 
must now be indicated. 
GASTEROMYCETES 
A puff-ball is a typical Gasteromycete. 
state the interior is a pure white, cellular, soft mass, 
known as the gleba. The thin shell or skin which surrounds 
it is the pevidium. It consists of two distinct layers : a thin 
outer one—the exoperidium — usually covered with spines, 
warts, or granules, which flake off in most cases, and dis¬ 
appear as the plant approaches maturity; a thicker inner 
one—the endoperidium —which either splits regularly at the 
apex or flakes away when the spores are ripe to allow of 
their escape. As the gleba ripens it differentiates into a 
series of minute chambers or cavities, which are narrow, 
curved, and separated from each other by anastomosing 
hyphae. The walls of the chambers consist of layers of 
branching hyphae, arranged with their tips pointing inwards. 
Each hypha bears a basidium carrying the spores—usually 
four—at its apex. At maturity the tissues of the gleba be¬ 
come moist and dissolve away. In this state the puff-ball 
A B 
Fig. 2. 
A. Ascus containing 
spores. B. Basi¬ 
dium bearing 
spores. 
In the young 
