228 THE MYCELIUM OF THE AGARICALES 



thrives upon dead tissues, as the heart wood, which they quickly 

 disorganize and render worthless. As in all the preceding groups 

 of fungi, the real plant body is a delicate mycelium that spreads 

 through the soil or decaying substances, as may readily be dem- 

 onstrated by splitting open a tree infested with one of the fungi 

 (Fig. 165 ). The " spawn " that is sold in seed stores for plant- 



Fig. 16= 



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 

 mushroom as a hall of hyphae on the strands of the mycelium. 1, section 

 nf i me 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 

 tin- velum, vl, appearing as a delicate membrane. 



ing in mushroom beds is a dried mass of decaying leaves and 

 straw mixed with earth, in which the mycelium of the mushroom 

 has been allowed to grow. Often the hyphae of the mycelium 

 lose their delicate character and become woven together, forming 

 rather dense woody strands or plates, a development frequently 



