MUSHROOM GROWING 



der certain favorable conditions each of 

 these minute cells is, however, capable of 

 germinating and producing first a germ 

 tube, ultimately a filamentous or thread- 

 like growth, known as the mycelium. This 

 mycelium arises from the first small germ 

 tube by subsequent branching and continued 

 ramifications, and under favorable condi- 

 tions it grows until the rapidly elongating 

 filaments penetrate the substratum in every 

 direction. The growth of the mycelium in 

 any suitable substratum yields a character- 

 istic *'spawn," and ''spawn" refers merely 

 to this phase of the mushroom growth in 

 visible or extensive quantity (Plate I\ c). 

 It is appropriately called the vegetative 

 phase. Spawn may also be produced from 

 fragments of the living tissue, if pure cul- 

 ture methods are employed, but this is dis- 

 cussed at length later. 



In this connection it may be said that the 

 mycelia of other fleshy or woody fungi in- 

 vade a great variety of substrata. Rich 

 earth, moist leaves of the forest floor, fallen 



14 



