Ch. X] 



THE TOADSTOOLS 



471 



known, including all of the edible Fungi excepting a few 

 Ascomycetes and Gasteromycetes ; and many are violently 

 poisonous. A few are parasitic and cause decay in living 

 trees. 



The Hymenomycetes fall into sub-groups according to 

 their method of spreading the hymenium. Largest and 

 most important are the Agaricinece, the Agarics or Gill 

 Fungi, of which the common Field Mushroom, now exten- 



Fio. 329. — Development of the sporophore of Amanita cernus, partly 

 diagrammatic ; X \. (After W. Hamilton Gibson.) 



sively cultivated for market, is a typical member (Fig. 327). 

 The mycelium, called "spawn" by the growers, ranges widely 

 in rich humus in fine, white, cobweb-like growths (Fig. 328). 

 Upon it, in places, develop compact rounded masses of 

 hyphal threads, within which the sporophores are gradually 

 differentiated. Later they break forth, and, as shown for 

 an allied form in Figure 329, the stalk or stipe grows apogeo- 

 tropically upwards, lifting the unfolding cap or pileus. The 

 original wrapping persists in part as the volva at the base, 



