Shade Tree and Timber Destroying Fungi. 



243 



many cases these areas of decay progress very irregularly, and 

 the figure becomes complicated and confused, especially in the 

 later stages of the decay of a tree, so that dark lines extend very 

 irregularly^ 



An examination of several maple trees bearing the Polypovus 

 igniarius gave evidence that the peculiar discoloration of the wood, 

 •accompanied the nwcelium of this species of fungus, and might 

 perhaps be sufficient to identify the species even where no fruit 

 form of the fungus was present. An examination of the trunks of 

 the beech bearing tlie Polyportis igniarius collected at Child wood, 

 IS^. Y., in 1896, presented the same characteristic coloration and 

 marking. The maple is said by some lumbermen to be troubled by 

 a disease which they term " black heart." It would be interesting 

 to know if the coloration produced in the heart by the action of 

 the mycelium of Polijporus igniarius is identical with this " black 

 heart " disease. 



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_:.^ili. 



77.— 



Effect of mycelium of Polyporus igniarius on ^cood of 



beech. 



It now becomes a mattter of interest to determine the mode of 

 entrance of the mvcelium of this funo-us into the tree. The fruit 

 bodies were found to be situated at wounds. These wounds, or 

 places of exit for the fruit form of the fungus, were " knot " holes 

 formed by the dying away of the lower limbs, and the failure of 

 the healing tissue to close the wound thus formed. The fruit form 

 can make its exit through quite a small opening, and usually does, 

 growing to larger dimensions outside as it ages. The first year's 



