THE HONEY FUNGUS 157 



are delignified from the outside towards the middle lamella, 

 leaving a layer of ceUulose. Then the cellulose also is 

 digested so that often whole walls disappear. The walls of 

 the bordered pits are digested gradually and they often 



FIG. 68. Armillaria mellea. Transverse section of larch wood showing 

 the ' black line ' ( x 4.50). 



crack through shrinkage in the process, and present various 

 curious figures, some of which Hartig has drawn (1879). 

 The wood never becomes honeycombed as it does with 

 Fomes annosus or as crumbly as with Polyporu^ Schweinitzii, 

 but it is much too "weak to be of any use for structural 

 purposes. 



The significance of the black line is obscure. It seems 



