THE STORY OF THE FUNGI 141 



dodendrons and azaleas, unless they take care 

 to put in some of the soil from the woods, which, 

 of course, is extremely Ukely to contain some 

 of the fungus mycelium. 



It has not been positively decided what part 

 the fungus plays in helping the roots, but it 

 seems that it probably renders aid in the absorp- 

 tion of moisture and possibly mineral salts. 

 Most of the trees and shrubs which have entered 

 into this alliance are able to support an exist- 

 ence in dry places ; this points to the fact that 

 they may be receiving special aid in the matter 

 of moisture supply. 



One should not jump to the conclusion that 

 all fungi in woods are living in this manner. 

 Undoubtedly many kinds flourish on the dead 

 organic matter, whilst it is quite hkely that 

 a number divide their attentions impartially 

 between the tree roots and the rotting leaves. 

 It is significant, however, that certain species 

 of fungus are almost always found in associa- 

 tion with definite trees. As an instance, which 

 anyone might observe, may be mentioned the 

 Fly Agaric, which always grows at the foot 

 of either fir or birch. This relationship between 

 trees and fungi is one which it is necessary to 



