lO 



Bulletin 138. 



a little enlarged, after the soil has been washed away from the spawn 

 and the buttons. Here the connection of the very young buttons with 

 the cords of spawn can be very clearly seen. These strands or cords 

 are made up of numerous minute whitish threads, known to botanists 

 as mycelium. In the group of fungi to which the mushroom belongs, 

 the mycelial threads are often interwoven into such strands in some- 

 what the same way as fibers are woven into cords or ropes, though not 

 in .^uch regular fashion, and of course they grow in this form. They 

 are often spoken of as cords or strands* of mycelium. In the soil the 

 mycelium grows and forms new strands, obtaining its nutriment from 

 the decaying humus and other vegetable matter. 



91. — Agaricus campcstris. Sections of ^^ buttons'''' of different sizes, 

 showing formation of gills and veil covering them. 



At certain points on the strands the mycelium grows to form these 

 rounded bodies known as buttons. At first they are of the size of pin 

 heads, and soon increase to the size of bird shot, then peas, when a 

 minute stem begins to appear with the button growing on its free end. 

 This increase in size, as well as the increase in the length of the stem, 

 lifts its head and the upper part of the stem from the ground, and it 

 rapidly expands into the mature mushroom. If we split several of 

 these buttons of different sizes down through the cap and the stem, 



*The term rhizomorph is also applied to these strands of mycelium. 



