FUNGI: MUSHROOMS 



203 



mushroom lives in the ground, f.nd grows here for several months 

 or even years, and at the proper seasons develops the mature 

 mushroom plant. The mycelium lives on decaying organic mat- 

 ter, and a large number of the threads grow closely together form- 

 ing strands, or cords, of mycelium, which are quite prominent 

 if they are uncovered by removing the soil, as shown in fig. 236. 

 423. From these strands the buttons arise by numerous threads 

 growing side by side in a vertical direction, each thread growing 

 independently at the end, but all lying very closely side by 



Fig. 237. 



Agaricus campestris ; sections of " buttons " of different sizes, showing iormation of gills 

 and veil covering them. 



side. When the buttons are quite small the gills begin to 

 form on the inside of the under margin of the knob. They 

 are formed from an interior ring of tissue near the end of the 

 young fruit body which appears before the end broadens into 

 a knob. From this ring of tissue threads grow downward in 

 radiating ridges, just as many ridges being started as there 

 are to be gills formed. The lateral tissue outside of this in- 

 terior ring of gills becomes the veil, and sections ot young but- 

 tons will disclose the gills in the minute cavity thus formed 

 (fig. 237). This curtain of mycelium which is thus stretched 

 across the gill cavity is the veil. As the cap expands more 

 and more this is stretched into a thin and delicate texture as 



