fungus are able to infect oak planks, beams, etc.; and the mycelium rapidly spreads on and in the wood, destroying the cell-walls, and causing the wood to shrink and crack and warp, and finally to fall to pieces. Thorough ventilation is fatal to the fungus and stops the rot.
Fig. 45.—Oak wood destroyed by Polyporus dryadeus, showing the very characteristic markings, like insect tunnels in a deep red brown matrix. (R. Hartig.)