The larger Fungi not described in this work are a few of the
Ascomycetes, including the Morel and its allies, the true ascus-
bearing Truffles and a limited number of Cup-fungi.
The microscope is unnecessary for the determination of the
greater number of the Basidiomycetes; nearly all are large and can
be satisfactorily examined by the unaided eye or with the assistance
of a hand-lens. A few forms found under Family iv Thekphoracece,
as Solenia and Cyphella, superficially resemble certain of the Ascomycetes,
as Peziza; but with a little experience even obscure forms
may be easily determined with the aid of a
simple lens. In some genera of the Thekphoracece
a microscopic examination of the hymenium is
sometimes desirable.
The Basidiomycetes are highly, plastic and
variable. No one species is constant in all its
characters, and a single example seldom wholly
accords with any other single example of the
same species. Examples which appear to be
intermediate between allied, and sometimes
between not allied, species are frequently met
with. About one species in ten is perhaps fairly
well and distinctly marked, but all species will
at times present aberrant characters. Any one
character is liable to fail; in the determination
of species, therefore, all the characters must be
studied together.
The Basidiomycetes are so named on
account of the spores being borne on more or
iess club-shaped cells named basidia (fig. 3).
Fig. 2 —Pteurotus
ostreains Quél.
, basidium ; b, sterigma ;
c, spore. X 750.
They are commonly borne in fours, on slender usually short threads
or supports named sterigmata. In rare instances, however, the
basidium bears two spores or perhaps only on e ; in these cases the
normal number of four is sometimes reverted to in well-developed
examples. In some species of the Tremellinacece the spores are
septate, and in some Gasteromycetes six or even more spores are
produced on a basidium.
The spores are usually smooth and simple or composed of one
cell; they are sometimes echinulate or warted. The commonest
form^ is oval or round; a few are multiangular. They are of microscopic
size, varying from about i 8/r to 3/r in length, and of various
colours.
The character of the basidium with its four naked spores is one
of great importance, as it separates the Basidiomycetes from the
Ascomycetes. In the latter the spores are borne usually in a series
of eight, within microscopic transparent elongated colourless sacs
named asa (fig. 4); the asci when ripe open at the apex and the
spores escape.
In an examination of the spore-bearing surface or hymenium of
the Basidiomycetes three kinds of cells are met with,— the ordinary
barren cells of the hymenium, the basidia with the spores, and
certain other large cells named cystidia.
The last-named are sometimes very small
or practically absent, as in C¿avaria ; in
other genera they are very large, as in
Coprinus (fig. 5), Hymenochoete (fig. 6) and
Penioptiora.
The more highly developed Basidiomycetes
as a rule bear white or slightly tinted
spores ; the lower or dung-borne species
usually produce black spores. In most
instances the spore-colour is permanent, but
in some species it vanishes and leaves the
spores hyaline. The colour of the spores
is often used as a generic or subgeneric
character ; the tint often, but not invariably,
gives the distinctive hue to the mature
hymenial surface. It is readily seen by
placing examples with the hymenium downwards
upon a piece of glass on which the
spores will be deposited.
At maturity, the spores of the Hymeno-
mycetes drop from the sterigmata and are
free in the air, but in the Gasteromycetes
the outer coats become naturally ruptured
before the spores can escape. In the Phal-
loidaceæ the sporiferous surface is at first
enclosed in a veil (volva), and even after the
elongation of the stem, the cap (pileus) is
covered by a very thin, almost invisible Fig. ¡..—Morckeiia escuimta Pers.
membrane ; when the spores are ripe they paiaphysis.
are enveloped in mucus which runs down
from the upper parts of the fungus to the lower, where there
is a gelatinous stratum; the spores may possibly germinate in the
decomposing gelatine. In the fetid species the odour attracts
swarms of fiies and sometimes small beetles to the sporiferous
mucus,^ which they eagerly devour. On flying away the insects
disseminate the spores, which have been seen to germinate after
having passed through flies. In the Lycoperdacece the spores are at
first enclosed in a peridium, and it is only when this is ruptured
that they are set free. Hymenogastraceæ are subterranean, or
nearly so, and the spores must either germinate in the decaying
substance of the mother plant or be carried away by larvæ
insects, etc. ’
In germination the spores open at one or both ends ; a transparent
germinal tube emerges (fig. 7) and forms strands, threads
or hyphæ of cellular mycelium. The strands branch and coalesce
B 2