number of sporidia.[R] The asci
themselves are soon dissolved. Simultaneously with the development of
sporidia, other reproductive bodies are produced direct from the
mycelium, and in some species as many as five different kinds of
reproductive bodies have been traced. The features to be remembered in
_Perisporiacei_, as forming the basis of their classification, are,
that the asci are saccate, springing from the base of the perithecia,
and are soon absorbed. Also that the perithecia themselves are not
perforated at the apex.

The four remaining orders, though large, can be easily characterized.
In _Tuberacei_, all the species are subterranean, and the hymenium is
mostly sinuated. In _Elvellacei_, the substance is more or less
fleshy, and the hymenium is exposed. In _Phacidiacei_, the substance
is hard or leathery, and the hymenium is soon exposed. And in
_Sphaeriacei_, although the substance is variable, the hymenium is
never exposed, being enclosed in perithecia with a distinct opening at
the apex, through which the mature spores escape. Each of these four
orders must be examined more in detail. The _Tuberacei_, or
subterranean _Ascomycetes_, are analogous to the _Hypogaei_ of the
_Gasteromycetes_. The truffle is a familiar and highly prized example.
There is a kind of outer peridium, and the interior consists of a
fleshy hymenium, more or less convoluted, sometimes sinuous and
confluent, so as to leave only minute elongated and irregular
cavities, and sometimes none at all, the two opposing faces of the
hymenium meeting and coalescing.[S] Certain privileged cells of the
hymenium swell, and ultimately become asci, enclosing a definite
number of sporidia. The sporidia in many cases are large, reticulated,
echinulate or verrucose, and mostly somewhat globose. In the genus
_Elaphomyces_, the asci are more than commonly diffluent.

The _Elvellacei_ are fleshy in substance, or somewhat waxy, sometimes
tremelloid. There is no peridium, but the hymenium is always exposed.
There is a great variety of forms, some being pileate, and others
cup-shaped, as there is also a great variation in size, from the
minute _Peziza_, small as a grain of sand, to the large _Helvella
gigas_, which equals in dimensions the head of a child. In the pileate
forms, the stroma is fleshy and highly developed; in the cup-shaped,
it is reduced to the external cells of the cup which enclose the
hymenium. The hymenium itself consists of elongated ferti