finally settle down, it may be, in other
states and continents from those in which they started. Millions perish
because of not finding a suitable resting place. Those spores that do
find a favorable resting-place, under right conditions, will begin to
germinate by sending out a slender thread-like filament, or hyphae, which
at once branches out in search of food material, and which always forms
a more or less felted mass, called mycelium. When first formed the hyphae
are continuous and ramify through the nourishing substratum from which
there arises afterward a spore-bearing growth known as the sporocarp or
young mushroom. This vegetative part of the fungus is usually hidden in
the soil, or in decayed wood, or vegetable matter. In Figure 3 is a
representation of the mycelium of the small pear-shaped puff-ball with a
number of small white knobs marking the beginning of the puff-ball. The
mycelium exposed here is very similar to the mycelium of all mushrooms.

In the pore-bearing genera the hymenium lines the vertical pores; in
teeth-bearing fungi it lines the surface of each tooth, or is spread out
over the smooth surface of the Stereum.

The development of the spores is quite interesting. The young basidia as
seen in Figure 2 are filled with a granular protoplasm. Soon small
projections, called sterigma (plural, sterigmata), make their appearance
on the ends of the basidia and the protoplasm passes into them. Each
projection or sterigma soon swells at its extremity into a bladder-like
body, the young spore, and, as they enlarge, the protoplasm of the
basidium is passed into them. When the four spores are full grown they
have consumed all the protoplasm in the basidium. The spores soon
separate by a transverse partition and fall off. All spores of the
Hymenomycetous fungi are arranged and produced in a similar manner, with
their spore-bearing surface exposed early in life by the rupture of the
universal veil.

In the puff-balls the spores are arranged in the same way, but the
hymenium is inclosed within an outer sack. When the spores are ripe the
case is ruptured and the spores escape into the air as a dusty powder.
The puff-balls, therefore, belong to the Gastromycetous fungi because
its spores are inclosed in a pouch until they are matured.

Another very large group of fungi is the Ascomycetes, or sac fungi. It
is very easily determined because all of its members develop their
spores inside of small membranous sac