DEVELOPMENT OF PLANTS 



241 



In certain species the mycelium is phosphorescent and the cause 

 of the pale light that sometimes appears upon moist decaying 

 wood, the so-called fox wood. The mycelium bears at various 

 places the complex fleshy or woody body commonly known as 

 the mushroom or toadstool. If the mycelium grows in a regular 

 manner, radiating outward in all directions, then the mushrooms 



Fig. 165. 



Fig. 166. 



Fig. 165. The mycelium of one of the Agaricales forming white masses 

 as it spreads through wood. 



Fig. 166. Development of a mushroom: 3, early appearance of the iriush- 

 room as a ball of hyphae on the strands of the mycelium, i, section of one 

 of these spherical masses of hyphae, showing the circular openings in which 

 the gills are developed. 2, a later stage with the gills formed and the velum, 

 vl, appearing as a delicate membrane. 



will have a similar arrangement. The older central portions of 

 the mycelium will finally die off", while the newer portions con- 

 tinue to radiate outward and produce the mushrooms, which con- 

 sequently appear in a more or less regular circle. In this way, 

 the fairy rings, which are often held in superstitious awe, come 

 about. 

 17 



