NAKED-SPORED FUNGI—BASIDIOMYCETES 125 



become the under, and consequently turned away from the 

 light. 



" In the Gastromycetes, with the exception of the species 

 constituting the genus Gaidiera, the hymenium is completely 

 concealed by a continuous wall or peridium, until the spores 

 are mature. ... As already stated, two leading features 

 stand out prominent in the evolution of the Hymenomycctcs : 

 the conversion of the primitive even hymenial surface into 

 gills, thereby increasing the spore-bearing area, and secondly, 

 the gradual concealment of the hymenium until the spores 

 are mature. In the Gastromycetes these two conditions are 

 present in the lowest forms, and persist throughout the group, 

 the very varied forms presented by the different orders being 

 the outcome of modifications of the sporophore in connection 

 with spore dissemination." 



We may now proceed to a closer analysis of the two 

 separate orders of Hymcnomycetes and Gastromycetes. 



