CHAPTER XIII. 

 DURABILITY OF WOOD. 



Decay in Wood is due to the breaking down of the 

 tissues by fungi. In some eases the fungus destroys the 



woody cells; in others it 

 uses up the starch found 

 in the cells and merely 

 leaves a blue stain (bluing 

 of lumber). Some kinds 

 of fungi attack only con- 

 ifers others only hard 

 woods; some are confined 

 to one species while othere 

 may affect several species, 

 but nrobably no one of 

 them attacks all kinds of 

 wood Fig. 63 shows the 

 Fig, 70— "Shelf" fungus on the discoloration of wood by a 

 stem of a pine (Hartig) a, gj^g]f fungus. The wood 

 Sound wood; o, resinous wood; 



c, partly decayed wood or Contains the fungus plant, 

 punk; rf, layer of living spore which, when ready to pro- 

 tunes; e, old spore tubes rilled . " 



up; /, fluted upper surface of duce its spores, Sends out 



the fruiting body of the fungus a shelf-liko bodv on the 



which gets its tood through a . ', m 



great numljer of fine threads Side of the WOod. These 



(the mycelium), its vegetative shelves contain the sporcs 



tissues penetrating the wood 



and causing it to decay. and may be found on many 



old decayed trees or stumps. 



Various odors are protluced in the wood by some of 



230 



