94 



EVOLUTION OF PLANTS 



spore-fruit, which may have a definite character, as in 

 the mushroom, where the " gills " (Fig. 25, A, #) .are 

 of this nature. The spores on germination form a 

 new mycelium, which in time produces spore-fruits. 



FIG. 25 (Basidiomycetes). A, a cluster of spore-fruits of the common mush- 

 room, arising non-sexually from the mycelium, /, which is buried in 

 the ground : B, a very young mushroom ; C, a section of an older one 

 showing the gills, g, upon which the spores are borne ; D, diagram 

 showing a section of a gill with the spore-bearing " basidia," b, cover- 

 ing its surface; E, i, young, n, mature basidium of a toadstool (Co- 

 prinus) , showing the spores borne at the summit ; F, spore-fruit of Tre- 

 mella, one of the lower Basidiomycetes; the spores cover the whole 

 surface of the irregular spore-fruit; G, a bird's-nest fungus (Cyathus) : 

 the spores are borne inside the "sporangia," sp, within the cup: H, 

 earth-star (Geaster), one of the Gasteromycetes allied to the puff-balls. 

 (Figs. A, B, after Warming; C, after Atkinson.) 



The lowest of the Basidiomycetes show analogies 

 with the rusts (^Ecidiomycetes), and do not have the 

 basidia restricted to any definite part of the spore-fruit, 

 but they may be produced all over it, as in the soft 

 gelatinous Tremella (Fig. 25, F), whose convoluted 

 soft yellow or orange masses are not uncommon on 



