es the soil or other substances
on which the fungus or mushroom grows. All fungi are either parasites or
saprophytes which have lost their chlorophyll, and are incapable of
supporting an independent existence.

There is a vast number of genera and species, and many have the
parasitic habit which causes them to enter the bodies of other plants
and of animals. For this reason all fungi are of economic importance,
especially the microscopic forms classed under the head of Bacteria.
Some recent writers are inclined to separate the Bacteria and
slime-molds from the fungus group, and call them fungus animals.
However this may be, they are true plants and have many of the
characteristics of the fungi. They may differ from the fungi in their
vegetative functions, yet they have so many things in common that I am
inclined to place them under this group.

Many, such as the yeast fungus, the various fermentative fungi, and the
Bacteria concerned in the process of decomposition, are indeed very
useful. The enrichment and preparation of soils for the uses of higher
plants, effected by Bacteria, are very important services.

Parasites derive their nourishment from living plants and animals. They
are so constituted that when their nourishing threads come within range
of the living plant they answer a certain impulse by sending out special
threads, enveloping the host and absorbing nutrition. Saprophitic plants
do not experience this reaction from the living plants. They are
compelled to get their nourishment from decaying products of plants or
animals, consequently they live in rich ground or leaf mold, on decayed
wood, or on dung. Parasites are usually small, being limited by their
host. Saprophytes are not thus limited for food supply and it is
possible to build up large plants such as the common mushroom group,
puff-balls, etc.

The spores are the seeds or reproductive bodies of the mushroom. They
are very fine, and invisible to the naked eye except when collected
together in great masses. Underneath mushrooms, frequently, the grass or
wood will be white or plainly discolored from the spores. The hymenium
is the surface or part of the plant which bears the spores. The
hymenophore is the part which supports the hymenium.

In the common mushroom, and in fact many others, the spores develop on a
certain club-like cell, called basidium (plural, basidia), on each of
which four spores usually develop. In morels these cells are elonga