subdivided, according to the disposition of the
spores and of the spore bearing surface, called the hymenium, into
various families.

The sporiferous fungi are arranged into four families, viz:

1. _Hymenomycetes_, in which the hymenium is free, mostly naked, or soon
exposed. _Example, "Common Meadow Mushroom."_

2. _Gasteromycetes_, in which the hymenium is enclosed in a second case
or wrapper, called a peridium, which ruptures when mature, thus
releasing the spores. _Example, Common Puff Ball._

3. _Coniomycetes_, in which the spores are naked, mostly terminal on
inconspicuous threads, free or enclosed in a perithecium. Dust-like
fungi. _Example, Rust of Wheat._

4. _Hyphomycetes_, in which the spores are naked on conspicuous threads,
rarely compacted, Thread-like fungi. _Example, Blue Mold._

Of these four subdivisions of the Sporifera, only the Hymenomycetes and
the Gasteromycetes contain plants of the mushroom family, and these two
together constitute the class known as the Basidiomycetes. The chief
distinction of the Basidiomycetes is that the naked spores are borne on
the summits of certain supporting bodies, termed basidia. These basides
are swollen, club-shaped cells, surmounted by four minute tubes or
spore-bearers, called sterigmata, each of which carries a spore. See
Figs. 3 and 4, Plate A.

These basides together with a series of elongated cells, termed
paraphyses, packed closely together side by side, and intermixed with
other sterile cells, called cystidia, constitute the spore-bearing
surface or hymenium of the plant.

To the naked eye this hymenium appears simply as a very thin smooth
membrane, but when a small portion of it is viewed through a microscope
with high powers its complex structure is readily observed and can be
carefully studied.

The _Sporidiferous_ fungi are represented by the families Physomycetes
and Ascomycetes. The first of these consists wholly of microscopic
fungi.

_Ascomycetes._--In the plants of this family the spores are not
supported upon basidia, but instead are enclosed in minute sacs or asci
formed from the fertile cells of a hymenium. In this connection it would
be well to state that Saccardo does not recognize the divisions
_Sporifera_ and _Sporidifera_ by those names.

They are nearly the equivalent of Basidiomycetes and Ascomycetes.

What Cooke names Physomycetes, Saccardo calls Phycomyceteae, introducing
it in his work between Gasteromyceteae and Myxomyce