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 

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

 stem of a pine (Hartig). a, g^^if fungus. The wood 

 Sound wood; o, resinous wood; • i /• 



c, partly decayed wood or contams the fungus plant, 

 punk; d, layer 6f living spore which, 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 ot the WOOd. J hese 

 (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 



