CHAP, V.—COMPARATIVE REVIEW.—ASCOMYCETES.—ELAPHOMYCES. 193 
It has already been said that the wall or outer wall of the perithecium is usually 
thick, and often firm and hard. That which is enclosed by it is on the contrary 
comparatively soft, and has usually great capacity for swelling in water; it comes 
out from the firm wall, when a perithecium is opened, like a soft kernel from its shell. 
Hence the old expression kernel or nucleus of the perithecium, which included 
all the soft parts described above, the asci first of all, and then the paraphyses, 
periphyses, hypothecium, and the soft layers of the wall; it had therefore no strict 
morphological foundation. 
Section LXII. The cleistocarps of the Cleistocarpous Ascomycetes are, 
as their name imports, surrounded by a wall, which remains closed and without 
an ostiole even when the spores are ripe, and the latter are only released by external 
influences which cause the rupture of the wall or by its decay. A great variety 
of special forms are included under these general characters. A number of these 
are in other respects scarcely anything else than simple pyrenomycetous perithecia 
without an ostiole. Among the Chaetomieae which have been carefully studied by Zopf 
there is one species, Chaetomium fimeti, which is distinguished from all the species 
nearest to it by this want of an ostiole. Others are removed from typical perithecia 
by further peculiarities of structure, the Erysipheae, for instance, Eurotium and 
Penicillium, which can only be briefly noticed here, as they will have to be described 
at greater length in a subsequent page. The sporocarps also of Sphaerophoron 
may be mentioned in this connection; their structure is given in Tulasne’, but 
their development has yet to be ascertained. All these sporocarps may be 
regarded as perithecia with a greater or less amount of deviation or simplification. 
The structure, on the other hand, of the compound sporophores of Elaphomyces, 
the Tuberaceae, Onygena, and Myriangium is quite different. The early stages 
of their development are still too little known, and we can count them among 
the sporocarps of the Ascomycetes only because they form asci and on the 
ground of some other analogies and resemblances; whether they can rightly be 
regarded as homologous with the others must for the present be left undecided. 
With this reservation a short description of these forms may be inserted in this 
-place, as it will be scarcely possible to recur to them while subsequently relating 
the histories of development. 
1. Elaphomyces. The sporocarps, which become of the size of a hazel-nut as 
they ripen, are round hollow bodies with a perfectly closed wall, usually known as the 
peridium, and enclosing the sporiferous tissue or gleda. The wall is some millimetres 
in thickness and consists of two firmly connected concentric layers. The inner of 
the two, the peridium in Vittadini’s narrower sense, is a dense and massive tissue 
of hyphae which are sometimes very thick-walled. The outer layer, the cortex of 
Vittadini, is thinner and of a consistence which varies with the species, and may be 
smooth, warted, hairy, or spiky. Its structure also varies with the species, and in most 
of them has not yet been described with exactness. In Elaphomyces granulatus it is 
hard and brittle and thickly beset with warts; the centre of each wart is formed of a 
conical group of irregularly shaped cells with their bright yellow walls everywhere 
strongly thickened. The bases of these cones are immediately on the inner layer, 
and touch each other by their sides. The intervals between the cones and the summits 
are occupied by a tissue without interstices composed of many layers concentric to 

1 See the figures in his Mém. sur les Lichens. 
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