96 HEART-ROT 
The dense blackness of the patches makes it impossible 
to observe the details of development in this stage until 
i} 
Fic. 34.—Black speck in the wood of the larch caused by Fomes annosus. 
Transverse section ( x 600). 
the black pigment has been removed. But the fact that 
these dark-walled hyphae are bleached by the action of 
almost any acid makes investigation possible. Convenient 
