, as will be more fully set
forth in the several specific descriptions. The peridium blends with the
hypothallus below when such structure is recognizable, either directly,
when the sporangium is sessile, or by the intervention of a _stipe_. The
stipe may be hollow, may contain coloring matter of some sort, or may
even contain peculiar spore-like cells or spores; is often furrowed, and
in some cases shows a disposition to unite or blend with the stalks of
neighboring sporangia. In many cases the stipe is continued upward, more
or less definitely into the cavity of the sporangium, and there forms
the _columella_, sometimes simple and rounded, like the analogous
structure in the _Mucores_, sometimes as in _Comatricha_, branching
again and again in wonderful richness and complexity.

Each sporangium is at maturity filled with numerous unicellular spores.
These are usually spherical, sometimes flattened at various points by
mutual contact; they are of various colors, more commonly yellow or
violet brown, are sometimes smooth (?), but generally roughened either
by the presence of minute warts, or spines, or by the occurence of more
or less strongly elevated bands dividing reticulately the entire
surface. The spores are in all cases small 3-20 mu, and reveal their
surface characters only under the most excellent lenses.

Associated with the spores in the sporangium occurs the _capillitium_.
This consists of most delicate thread-or hair-like elements, offering
great variety both in form and structure. The threads composing the
capillitium are not to be regarded, even when free, as cells, nor even
of cellular origin; probably, as would appear from the researches of
Strasburger and Harper, all forms of capillitial threads arise in
connection with vacuoles in the protoplasmic mass. "Whether the thread
is hollow or solid, simple or branched, free or connected with the
peridium or a columella,--these are entirely secondary conditions,
depending on the extent and form of the vacuoles."[6] They may occur
singly or be combined into a net, they may be terete or flat, attached
to the peridial wall or free, simple or adorned with bands or spires and
knobs in every variety, uniform or profusely knotted and thickened at
intervals, and burdened with calcic particles. In many cases, the
capillitium contributes materially to the dispersal of the spores; in
others, it doubtless contributes mechanically to the support of the
peridial wall, an