there are four types with respect to the presence or absence of
the ring and volva. In the first type both the ring and volva are
absent, as in the common fairy ring mushroom, _Marasmius oreades_; in
the genus _Lactarius_, _Russula_, _Tricholoma_, _Clitocybe_, and others.
In the second type the ring is present while the volva is absent, as in
the common mushroom, _Agaricus campestris_, and its close allies; in the
genus _Lepiota_, _Armillaria_, and others. In the third type the volva
is present, but the ring is absent, as in the genus _Volvaria_, or
_Amanitopsis_. In the fourth type both the ring and volva are present,
as in the genus _Amanita_.

=The Stem is Absent in Some Mushrooms.=--There are also quite a large
number of mushrooms which lack a stem. These usually grow on stumps,
logs, or tree trunks, etc., and one side of the cap is attached directly
to the wood on which the fungus is growing. The pileus in such cases is
lateral and shelving, that is, it stands out more or less like a shelf
from the trunk or log, or in other cases is spread out flat on the
surface of the wood. The shelving form is well shown in the beautiful
_Claudopus nidulans_, sometimes called _Pleurotus nidulans_, and in
other species of the genus _Pleurotus_, _Crepidotus_, etc. These plants
will be described later, and no further description of the peculiarities
in form of the mushrooms will be now attempted, since these will be best
dealt with when discussing species fully under their appropriate genus.
But the brief general description of form given above will be found
useful merely as an introduction to the more detailed treatment. Chapter
XXI should also be studied. For those who wish the use of a glossary,
one is appended at the close of the book, dealing only with the more
technical terms employed here.

[Illustration: FIGURE 3.--Agaricus campestris. Soil washed from the
"spawn" and "buttons," showing the young "buttons" attached to the
strands of mycelium. (1-1/4 natural size.)]

CHAPTER II.

DEVELOPMENT OF THE MUSHROOM.

When the stems of the mushrooms are pulled or dug from the ground, white
strands are often clinging to the lower end. These strands are often
seen by removing some of the earth from the young plant, as shown in
Fig. 2. This is known among gardeners as "spawn." It is through the
growth and increase of this spawn that gardeners propagate the
cultivated mushroom. Fine specimens of the spawn of the cultivated