CHAPTER XIII. 

 DURABILITY OF WOOD. 



Decay in Wood is due to the breaking down of the 

 tissues by fungi. In some cases 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 others 

 may affect several species, 

 but probably no one of 

 them attacks all kinds of 

 wood. Fig. 63 shows the 

 discoloration of wood by a 

 shelf fungus. The wood 



FIG. 70. "Shelf" fungus on the 

 stem of a pine (Hartig). a, 

 Sound wood; b, resinous wood; 

 c, partly decayed wood or contains the fungus plant, 



partly c 



punk; d, layer of living spore w hich, when ready to pro- 

 tubes; e old spore tubes filled 



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



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



which gets its food through a - " 



great number of fine threads Side oi the wood. Ihese 



(the mycelium), its vegetative shelves contain the spores 

 tissues penetrating the wood 



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



old decayed trees or stumps. 



Various odors are produced in the wood by some of 



230 



