CHAPTER V. COMPARATIVE REVIEW.- ASCOMFCETES. SPHYRIDIUM. 221 



and form asci. No paraphyses are formed. The whole process shows great simi- 

 larity with that described by Bauke in Pleospora. 



The formation of the perithecia in the stroma of Epichloe is undoubtedly very like 

 that of Claviceps ; so probably, according to Fisch, is the same process in Cordyceps 

 (C. militaris, C. ophioglossoides, and C. capitata). The perithecia also of Nectria, 

 according to Janowitsch's earlier observations and of Cucurbitaria according to Bauke's 

 report, are formed without initial archicarps, antheridia, or spermatia, but simply by late 

 differentiation of portions of the stroma which were at first uniformly parenchymatous 

 or consisted of closely woven hyphae ; in both genera there is also a dissolution of 

 the original central pseudo-parenchyma to make the inner cavity and a formation of 

 paraphyses between the asci. But these older investigations require to be repeated at 

 the present day. R. Hartig's account of Nectria mentioned above (page 2 1 7) is specially 

 deserving of attention ; he suspects that the perithecia in N. ditissima are produced from 

 archicarps which are formed originally superficially on the stroma under a covering 

 of gonidia-forming hyphae, and are then inclosed by branches from adjacent hyphae, 

 and that in conjunction with these latter hyphae they then give rise to the primordial 

 pseudo-parenchymatous formations from which Janowitsch's investigation sets out. 

 The possibility of similar processes is not entirely excluded by the accounts which we 

 possess in the case also of Epichloe. 



15. Van Tieghem gives the name of Ascodesmis to two small Discomycetes 

 which in the full-grown state look like small Ascoboli and are distinguished by 

 reticulate thickenings of their spore-membranes. He describes the development 

 of their apothecia from specimens cultivated on microscope-slides in the following 

 manner. A slightly bent lateral branch rises from a cell of a filament of the mycelium, 

 and, after a short increase in length, branches in a pseudo-dichotomous manner ; this 

 mode of branching is repeated through several orders in planes which intersect each 

 other alternately, and the successive branches have a similar curvature. At length they 

 all become woven together into a cushion of compact pseudo-parenchyma, which is 

 attached on one side to the mycelial filament by a short stalk. Then closely crowded 

 paraphyses shoot out from the superficial cells on the opposite side, and then the asci 

 one after another from the same surface and between the paraphyses. We are not 

 told whether any difference appears between the ascogenous cells and those which 

 form paraphyses, or if the asci at least which follow one another spring from distinct 

 ascogenous hyphal branchlets. 



1 6. The apothecia of Sphyridium fungiforme, S. placophyllum and 

 Cladonia Papillaria consist in the mature state of close-set paraphyses and of asci 

 inserted between them, and the asci arise from distinct ascogenous hyphae in the 

 hypothecium. According to Krabbe 1 the commencements of these apothecia are 

 peripheral shoots from the outer surface of the thallus, and the layer of paraphyses 

 first makes its appearance and afterwards the ascogenous hyphae with the asci. No 

 trace was observed of a distinct carpogonium or archicarp, as the source of the 

 ascogenous hyphae, or of any co-operation of spermatia; on the contrary, the 

 ascogenous hyphae are branches of ' ordinary ' hyphae, hyphae, that is to say, which 

 are not distinguishable from vegetative hyphae and from those which form 



1 Dot. Ztg. 1882. 



