344 TEXT-BOOK OF FUNGI 



Many species have conidial forms of reproduction. 

 Distinguished from Hemibasidiomycetes by the basidia 

 being one-celled. 



KEY TO THE SUB-ORDERS 



Hymenium naked and exposed from the first, or at all 

 events before the spores are mature. Hymenomycetes. 



Hymenium enclosed in a special covering until the 

 spores are mature. Gasteromycetes. 



HYMENOMYCETES 



The principal feature of this group consists in the 

 hymenium or spore-bearing surface being exposed from 

 the first, or at all events before the spores are mature. 

 Two leading ideas are persistently kept in view during the 

 evolution of the group. One of these is the production of 

 the greatest area of spore-bearing surface with the least 

 expenditure of material. The other idea is concerned with 

 the protection of the hymenium from injury, whether due 

 to climatic conditions or the attacks of animals. The 

 gradual progress of these ideas is followed in detail in 

 treating of the respective families forming the Hymenomy- 

 cetes, and it is sufficient at present to state that both ideas 

 are most perfect in the highest and newest group, Poly- 

 poreae, where the hymenium is protected against adverse 

 weather in the interior of hollow tubes, and against the 

 attacks of living enemies by the indurated consistency of 

 the sporophore, which in the highest species is hard and 

 woody. This comparative perfection has led, for the first 



