332 COMPARATIVE MORPHOLOGY OF FUNGI 



development very suggestive of the Tuberales; hence in that order we 

 shall return to this series. 



Pyronemaceae. — The significance of this family does not lie in its 

 fructifications, but in the relationships of its sexual organs. They form 

 an extremely primitive group and include forms which are lower than 

 any of the previously discussed types of the Inoperculatae. Their 

 fructifications rest on single hyphae or hyphal tissues, and are merely 

 loose, open, immarginate, ascigerous discs, penetrated by paraphyses. 

 Sometimes one consists of a tuft of asci resting upon a more or less well- 

 developed hypothecium. Only two genera will be discussed here: 

 Pyronema, morphologically higher with a well-developed hypothecium, and 

 Ascodesmis, morphologically simpler with poorly developed or almost 

 no hypothecium. An idea of Pyronema may be derived from the figure 

 of Sphaerosoma fuscescens (Fig. 219, 1), if one imagines the apothecial 

 margin absent so that the ascigerous hymenium, as in the Phillipsielleae 

 and Agyrieae, covers the whole top of the hypothecium. Figure 223, 5 

 shows Ascodesmis; if one imagines this ascus tuft laid on or in a loose 

 subiculum, one has a cross section through one of the Gymnoascaceae. 



Pyronema confluens, the best known representative (Harper, 1900; 

 Dangeard, 1907; Kosaroff, 1907; Claussen, 1912), is gregarious on the 

 bottom of damp piles of charcoal, occasionally on pots of sterilized earth, 

 and forms there its lenticular, 1 to 3 mm. broad, flesh or rose-red fructifi- 

 cations (apothecia) which are generally confluent in groups (hence the 

 species name) resting upon fine hyphal tissues. 



The hyphal cells are multinucleate. At the formation of the fructifica- 

 tion one, more rarely several, hyphae fork repeatedly and grow upwards 

 so that small tufts of rosettes result. Originally this whole branching 

 system is unicellular. Later the single multinucleate branches are 

 abjointed. Such an abjointed uninucleate, cellular branch (the later 

 ascogonium) attains a thick, clavate structure and, while at its base one 

 or two stipe cells are formed, its tip elongates to a multinucleate papilla, 

 the later trichogyne. Subsequently, its lower end is abjointed from the 

 swollen ascogonium beneath (Fig. 220, 1). 



In the immediate vicinity of the ascogonial branch and on the same 

 hypha there arises an antheridial branch (and this occurs very early) in 

 which the first contact of the two organs stimulates branching, such as 

 has just been described for the female organ. The female branches 

 are always somewhat ahead of the male in development. Finally, in 

 the latter, the multinucleate end cells and one or two stipe cells are 

 abjointed from the hypha and develop to clavate antheridia (Fig. 78). 



During the further development, the nuclei in both antheridia and 

 ascogonia increase much in size; those of the trichogynes, however, 

 remain small and gradually degenerate (Fig. 220, 2). Both in anther- 

 idium and ascogonium, a few nuclei degenerate before plasmogamy. The 



