542 



THE BASIDIOMYCETES 



(1927). The mycelium is abundantly intercellular, branched 

 haustoria occurring within the host cells. The clavate basidia 

 extend above the surface between the epidermal cells, much as 

 do the asci in Taphrina. Each basidium bears from 2 to 8 basidio- 

 spores. In culture the basidiospores of most species of Exoba- 



Remnants of 

 universal veil 



Pileus 

 or cap 



Volva, part of 

 universal veil 



Bulbous base 

 of stipe 



Mycelium 



Fig. 128. Structural features of a mature fruit body of Amanita, in diagram. 



sidium germinate in the manner of yeasts; E. rhododendriy which 

 forms germ tubes, is a notable exception. 



Host differences have been largely employed in distinguishing 

 species of Exobasidium, but it appears that the validity of such 

 specific distinctions can be established only by reciprocal infec- 

 tion experiments. Such experiments remain to be performed. 



