AMERICAN WOOD-PRESERVERS' ASSOCIATION 19 



surface of the wood. They consist of minute, flask-shaped structures, 

 often with long, bristle-like necks which are visible to the unaided eye 

 as rigid, black, brittle hairs on the surface of the wood. 



The most characteristic feature of these fungi, however, is the 

 grayish-blue discoloration produced. The stain may be quite uniform 

 over considerable areas, or it may be limited. It is caused by the pene- 

 tration of the mycelium into the sapwood mainly through the pith rays. 

 As the fungus lives mainly on the starches, sugars, etc., stored in the 

 pith rays, it does not affect the strength of the wood and hence is of 

 no economic importance in connection with tie timbers. 



In the region investigated both pine and red gum are particularly 

 susceptible. 



OLIVE-BLACK MOLD (LASIOSPHAERIA PEZIZULA) 

 (Plate III, Fig. 1; Plate VII, Fig. 9) 



This fungus was frequently seen on the ends of red gum and 

 beech ties. It develops as a blackish mold-like growth which is dis- 

 tinctly tinged with olive green. The mycelium is compact, and upon 

 it are seated minute, depressed, spherical, brownish-black fruiting-bodies 

 much smaller than a pin head. 



The mycelium penetrates the wood to a considerable extent. It 

 produces a bluish-black discoloration quite similar to the blue stain, 

 but does not appreciably attack the fiber, and hence need not be dis- 

 criminated against. 



