94 



EVOLUTION OF PLANTS 



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

 the mushroom, where the " gills " (Fig. 25, A, g') 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 hurled in 

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

 showing the gills, ,9, 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, 11, 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 AVarming ; C, after Atkinson.) 



The lowest of the Basidiomycetes show analogies 

 with the rusts (^cidiomycetes), 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 



