IV] 



PEZIZALES 



lOI 



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 Ascodesrnis and Pyronema, species of 

 both of which have been somewhat fully investigated. 



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

 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. 60 f). Subsequently the oogonium enlarges 

 somewhat and undergoes septation ; large ascogenous hyphae, usually about 

 three in number, bud out from it (fig. 6og), and quickly give rise to asci 

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

 spherical and have a characteristically sculptured epispore (fig. 602). At 



Fig. 59. Ascodesrnis nigricans Van Tiegh. ; apo- 

 thecium, x 340 ; after Claussen. 



^ 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. 



