HOW PLANTS OBTAIN FOOD. 89 



colder parts of the year often they may be seen in forcing houses, 

 especially those cellars devoted to the propagation of the mush- 

 room of commerce. 



188. These strands are made up of numerous threads of the 

 mycelium which are closely twisted and interwoven into a cord 

 or strand, which is called a mycelium strand, or rhizomorph. 

 These are well shown in fig. 236, which is from a photograph of 

 the mycelium strands, or ' ' spawn ' ' as the grower of mushrooms 

 calls it, of Agaricus campestris. The little knobs or enlargements 

 on the strands are the young fruit bodies, or "buttons." 



189. While these threads or strands of the mycelium in the 

 decaying wood or in the decaying organic matter of the soil are 



Fig. 80. 



Sterile mycelium on wood props in coal mine, 400 feet below surface. (Photographed by 

 the author.) 



