THE FUNGI : ASCOMYCETES AND BASIDIOMYCETES 261 



open by the growth of sterile hairs or paraphyses, forming an open, cup- 

 shaped or discoid apothecium lined with asci. 



The group includes many common Fungi which occur on dead and decay- 

 ing wood. Many of the fruiting bodies are brightly coloured and are con- 

 spicuous in woodlands during the autumn. We shall take as our examples 

 Pyronema cotiJJuens and Peziza vesiculosa. 



Pyronema confluens (P. omphalodes) 



This little Ascomycete is sometimes found growing very abundantly in 

 woods on burnt places, especially among half-charred masses of leaves, 

 though it may also occur among damp well-decayed leaves even when there 

 has been no fire (Fig. 253). 



Fig. 253. — Pyronema confluens. Confluent apothecia on 

 soil, about twice life size. 



The mycelium is glistening white and resembles a frost-like tracery on 

 the dark substratum on which it grows. It is on this mycelium that the 

 sex organs are produced and only a few days are required for the development 

 of these sex organs into mature fruiting bodies. 



Pyronema confluens has gained a reputation out of all proportion to its 

 importance either ecologically or morphologically, on account of the amount of 

 work which has been done on its sexual reproduction, for it is the only known 

 member of the Pezizales in which a complete sexual apparatus exists. It 

 may therefore be regarded as the starting-point of a series of types showing 

 a degeneration through which the true function of the sex organs is lost, and 

 finally the organs themselves, till the sexual act is reduced to the fusion of 

 two nuclei within a cell which is derived directly from the vegetative cells 

 of the fruiting body, as we shall see in Peziza. As more and more of these 

 simpler Pezizales are investigated more stages are supplied in this degenera- 

 tion series, but so far Pyronema confluens stands alone in having the complete 

 apparatus still present and functional. It is for this reason that we must 

 consider the structure in some detail. 



