IV] 



PEZIZALES 



101 



Pyronemaceae 



The Pyronemaceae are a small group distinguished from the other 



Pezizales by the fact that the peridium, or lateral boundary of protective 



hyphae around the fruit, is not well developed. 



This is not always regarded as a sufficiently important character to 



warrant their separation from the Pezizaceae and many authors include 



them in that group. 



The only important genera are Ascodesmis and Pyronema, species of 



both of which have been somewhat fully investigated. 



Ascodesmis nigricans^ (fig. 59) is a small coprophilous form. 



The sexual organs appear in artificial culture about forty-eight hours 



after the germination of the spore. 



Stout, multinucleate hyphae grow 



up from the mycelium and dicho- 

 tomize (fig. 6oa) to give rise to some 



six or eight archicarps. Near these, 



and usually from the same filament, 



one or two antheridial hyphae arise. 



They grow towards the archicarps 



(fig. 60 b) and dichotomize (fig. 60 c), 



while around each of their terminal 



cells or antheridia, an archicarp 



becomes wrapped (fig. 60 d). 



In the meantime walls are laid 

 down, so that the various archicarps 

 and antheridia become cut off from 

 their neighbours, and each archicarp 

 divides transversely to form a tri- 

 chogyne and an oogonium. The trichogyne usually contains two nuclei, 

 the oogonium five or six and the antheridium about the same number. The 

 nuclei of the trichogyne soon degenerate, and, as observed by Claussen, the 

 wall between this cell and the antheridium is broken down (fig. 60 e\ so 

 that open communication is established. The male nuclei pass into the 

 oogonium, where for a time ten or twelve nuclei may be counted, then fusion 

 of these in pairs takes place (fig. 6o/). Subsequently the oogonium enlarges 

 somewhat and undergoes septation ; large ascogenous hyphae, usually about 

 three in number, bud out from it (fig. 60^-), and quickly give rise to asci 

 (fig. 60 h). Ascus formation is apparently quite typical, the spores are 

 spherical and have a characteristically sculptured epispore (fig. 6o/). At 



1 Claussen described the cytology of this species under the name of Boudiera hypoborea Karst. ; 

 see Cavara, Ann. Myc. iii, 1905, p. 363, and Dangeard, Botaniste, x, 1907, p. 247, for nomenclature. 



59- Ascodesmis nigricans Van Tiegh. ; apo- 

 thecium, X34o; after Claussen. 



