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 LXIL 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 thari 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 1 , 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 sporophpres 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. 



i. 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 

 peridtum, and enclosing the sporiferous tissue or gleba. 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 



. * See the figures in his Mem. sur les Lichens. 

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