LIFE HISTORIES OF FUNGI 283 



buttons enlarge, a little chamber forms near the tip (Fig, 

 205), and into this chamber some of the hyphae grow, form- 

 ing the ''gills," with their ''fruiting" surface. While the 

 gills are forming other hyphas form a veil, extending from 

 the stipe to the edge of the pileus, and protecting the 

 gills until the spores are ripe. By continued growth of 

 the pileus the veil becomes ruptured, thus allowing the 

 spores to escape. It has been found that the spores do 

 not merely fall from the sterigmata f rom their own weight, 

 but that they are forcibly expelled. 



Entire new mushrooms may also be obtained by growing 

 pieces of a young plant on suitable nutrient media. From 

 such pieces mycehum is produced which ultimately bears 

 the "buttons." 



OUTLINE OF LIFE HISTORY OF MEADOW-MUSHROOM 



Spore (Basidiospore) 



4. 



Mycelium 



J- 



Binucleate cells 



4.4. 



Young sporophore ("Buttons") 



Mature sporophore (the "Mushroom") \ ^!^^ 



Gills 



II 



Hymenium 



4.4, 



Basidium {Nuclear fusion) 



4, \ Reduction 

 Sterigma 



i 



Spore (Basidiospore) 



272. Other Classes of Fleshy Fungi.— In addition to 

 the gill-bearing fungi (Agaricaceae) , there are many other 

 families of Basidiomycetes, one bearing the fruiting sur- 



