I 9 4 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



mycelium of this fungus destroys the structure of the 

 wood in a manner so similar to that of the Merulius 

 that the sawyers and others do not readily distinguish 



FIG. 24. A piece of pine-wood attacked by the mycelium of Polyporus vaporarius. 

 The timber has warped and cracked under the action of the fungus, becoming of 

 a warm brown colour at the same time ; in the crevices the white strands of felt-like 

 mycelium have then increased, and on splitting the diseased timber they are found 

 creeping and applying themselves to all the surfaces. Except that the colour is 

 snowy white, /instead of gray, this mycelium may easily be mistaken for that of 

 Merulius. The fructification which it develops is, however, very different. 

 (After R. Hartig.) 



between the two. The mycelium of Polyporus 

 vaporarius forms thick ribbons and strands, but 

 they are snowy white, and not gray like those of 



