SEED AND ROOT 



161 



Photo by] 



FIG. 198. COMMON MUSHROOM ( Agaricua campestris). 



[E. Step. 



The mushroom is not the fungus but its fructification, the plates or gills under the cap (ptteus) producing millions of 



microscopic spores which have the power under suitable conditions of reproducing the thread-like mycelium which is 



the working stage of the fungus. About one-fourth of the natural size. 



pestrix, fig. 198), the spores are borne on the under side of the frail 

 umbrella-like cap (the pileus) on minute stalks. A powerful microscope 

 is needed to examine them, as individually they are quite invisible to the 

 naked eye. When these spores fall to the ground they begin to swell, 

 and presently put out cellular threads of wonderful tenuity, which grow 

 and branch, and continue growing and branching, till they form a beauti- 

 ful white flocculent mass the " Mushroom spawn " of our markets from 

 which new Mushrooms may be raised. Thus the spore does not develop 

 at once into a perfect Mushroom, with thick stem and spreading disc- 

 shaped fructification; there are two distinct stages of development. The 

 close pile of whitish threads botanically known as- the 'mycelium appears 

 first ; and then, out of the mycelium, arises the fructification or Mush- 

 room, consisting of stalk and cap. It is important to bear these successive 

 stages of development in mind. 



When demolishing old houses, one frequently finds on the damp rafters 

 or underneath the planks the mycelia of other Fungi, spreading from a 

 centre nearly equally in all directions, and so delicate that a breath might 

 dissipate them; but even in quite new houses one may meet with the 

 terrible " dry rot" that will soon make havoc with the timber, and reduce 

 it to tinder. In the species common in woods and meadows, it is the 

 fructification alone which attracts our notice. In the latter case, indeed, 

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