148 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



animals as they pass over and under the spore- 

 bearing mass. 



When the mycelium obtains a hold in the root, it 



FIG. 12. Piece of root of spruce-fir, with the mycelium of Trametes radiciperda 

 (after Hartig) enlarged about 3 times. The white mycelium spreads in a fan-like 

 manner over the surface beneath the cortex, as seen in the figure where the latter 

 has been lifted and removed (a). Here and there the mycelium bursts through 

 the cortex in the form of white protuberances (b\ to form the fructifications. 



soon spreads between the cortex and the wood, 

 feeding upon, and of course destroying, the cambium. 



