422 



COMPARATIVE MORPHOLOGY OF FUNGI 



With the derivation from conidiophores, one must consider that in 

 the Basidiomycetes secondary spore forms may appear in the diplont. 

 With the decline of sexual organs and of sexuality, the original zeugites 

 and gonoconts, the asci, were lost; caryogamy and meiosis had been 

 transferred to the secondary spore forms and fixed there; they had stabi- 



le 



V '.'-■.-*- 



Fig. 272. — Diagrammatic comparison of ascogenous hyphae of Pyronema with clamp 



hyphae of Basidiomycetes. 



lized the form and spore number in secondary forms by limitation of 

 nuclear divisions and developed them to organic entities, the basidia, 

 characterized by simultaneous spore formation. This process could have 

 happened several times within the Ascomycetes so that the basidia, particu- 

 larly the different types of phragmo- and holobasidia, were distinguished 

 as convergent polyphylectic structures. On the other hand, one might 



