The volva is a membrane which envelops the entire plant in embryo,
giving it the appearance of an egg. It originates at the base of the
mushroom and furnishes it, during its foetal life, with the means of
support and nourishment. Its texture is so delicate that it generally
disappears, leaving very little trace of its existence on the adult
plant. In many of the volvate species this organ exists only so long as
they are under ground, and some mycologists restrict the term "volvati"
to such only as retain it afterwards. As the young plant expands it
breaks through the top of this volva or wrapper, and, emerging, carries
with it patches of the membrane on the upper surface of the cap. These
are more or less prominent, numerous, and thick, sometimes irregularly
disposed, sometimes regularly in the form of plates, warts, etc. At the
base of the stem of the mushroom the remains of the volva are seen in
the form of a sort of wrapper. This is more or less ample, thick, and
ascending. It is called _free_ when it is loose or easily detached from
the stem, and _congenital_ when it cannot be separated from it without
laceration. In some species it is distinctly membranous, and in others
floccose, and friable in character, sometimes appearing in ridges as a
mere border, at others broken up into scales, and, as the plant matures,
wholly disappearing. The volva is a feature of great importance in the
study of the Agaricini, of the subgenera Amanita, Volvaria, etc.

THE MUSHROOM VEIL.

The veil is not a constant feature in the Agaricini, at least it is not
always visible. When present it consists of a membrane which extends
from the margin of the cap to the stem, veiling or protecting the gills.
This membrane, called the cortina, has given its name to a numerous and
important class of mushrooms (the _Cortinarias_). It is generally
white, soft, slightly spongy, cottony, at times fibrillose or even
slightly fibrous, again in texture comparable to the spider's web, and
may be even powdery or glutinous. It exists intact only in the youth of
the plant. It is not visible in the developing mushroom, at least while
the cap is closely pressed against the stem, but as the cap expands the
membrane extends and finally breaks, leaving in some species its
remnants upon the margin of the cap and upon the stem in the usual form
of a ring or a mere zone. When the stem is not ringed the veil rises
high upon the stalk, stretches across to meet the e