HOW PLANTS OBTAIN FOOD, 8$ 



winter and colder parts of the year often they may be seen in 

 forcing houses, especially those cellars devoted to the propaga- 

 tion of the mushroom of commerce. 



156. The fungus strands. These strands are made up ol 

 numerous threads of the mycelium which are closely twisted 

 and interwoven into a cord or strand, which is called a myce- 

 Uum strand, or rhizomorph. These are well shown in fig. 61, 

 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." 



157. Mats of mycelium are sometimes very extensive. 

 While these threads or strands of the mycelium in the decaying 

 wood or in the decaying organic matter of the soil are not true 

 roots, they function as roots, or root hairs, in the absorption of 

 food materials. In old cellars and on damp soil in moist 

 places we sometimes see fine examples of this vegetative 

 part of the fungi, the mycelium. But most magnificent 

 examples are to be seen in abandoned mines where timber has 

 been taken down into the tunnels far below the surface of the 

 ground to support the rock roof above the mining operations. 

 I have visited some of the coal mines at Wilkesbarre, Pa., and 

 here on the wood props and doors, several hundred feet below 

 the surface, and in blackest darkness, in an atmosphere almost 

 completely saturated at all times, the mycelium of some of the 

 wood-destroying fungi grows in a profusion and magnificence 

 which is almost beyond belief. 



158. Form of the mushroom. A good example for this 

 study is the common mushroom (Agaricus campestris). 



This occurs from July to November in lawns and grassy fields. 

 The plant is somewhat umbrella-shaped, as shown in fig. 62, 

 and pos*sesses a cylindrical stem attached to the under side of 

 the convex cap or pileus. On the under side of the pileus are 

 thin radiating plates, shaped somewhat like a knife blade. 

 These are the gills, or lamellae, and toward the stem they are 



