96 



HEART-ROT 



The dense blackness of the patches makes it impossible 

 to observe the details of development in this stage until 



FIG. 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 



