THE HONEY FUNGUS 



157 



are delignified from the outside towards the middle lamella, 

 leaving a layer of cellulose. Then the cellulose also is 

 digested so that often whole Avails 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 di'awn (1879). 

 The wood never becomes honeycombed as it does with 

 Fomes annosus or as crumbly as with Polyporus Schweinitzii, 

 but it is much too weak to be of any use for sti'uctural 

 l^urposes. 



The significance of the black line is obscure. It seems 



