obose sporidia are quite smooth and
colourless. The warted sporidia may be observed in _Genea verrucosa_,
the spinulose in _Tuber nitidum_, and the areolate are present in
_Tuber aestivum_ and _Tuber excavatum_, in which the epispore is
divided into polygonal alveoli, bounded by thin, membranaceous,
prominent partitions. This form of sporidium is very beautiful. In all
no special provision is made for the dissemination of the sporidia,
as, from their subterranean habit, none would be available save the
ultimate dissolution of the external integuments. As they are greedily
devoured by several animals, it is possible that they may be dispersed
through the excrements.

In the _Perisporiacei_ the perithecium has no proper orifice, or
ostiolum, for the discharge of the mature sporidia, which are usually
small, and are disseminated by the irregular rupture of the somewhat
fragile conceptacles. The asci are usually more or less saccate, and
the sporidia approximate to a globose form. The asci are often very
diffluent. In _Perisporium vulgare_ the ovate brown sporidia are at
first, and for some time, attached together in fours in a concatenate
or beaded manner. In some species of _Erysiphei_ the conceptacle
encloses but a single sporangium, in others several, which are
attached together at the base. In some species the sporangia contain
two, in others four, in others eight, and in others numerous sporidia.
In _Chaetomium_ the asci are cylindrical, and in most cases the
coloured sporidia are lemon-shaped. When the conceptacles are fully
matured, it is commonly the case that the asci are absorbed and the
sporidia are free in the interior of the conceptacles.

[Illustration: FIG. 66.--Asci, sporidia, and paraphyses of _Ascobolus_
(Boudier).]

Of the fleshy _Discomycetes_ the genus _Peziza_ may be taken as
the type. If the structure which prevails in this genus be brought
to mind, it will be remembered that the hymenium lines an expanded
cup, and that the asci are packed together, side by side, with their
apices outwards, and their bases attached to a substratum of cells
which form the inner layer of the receptacle. The sporidia are
usually eight in each ascus, either arranged in single or double
rows, or irregularly grouped together. The asci are produced in
succession; the later, pressing themselves upwards between those
previously developed, cause the rupture of the mature asci at the
apex and the ejection of the sporidia wi