PLESHY AND WOODY FUNGI 



225 



three species of which M. lacrymans, the dry-rot fungus, is most impor- 

 tant. This fungus is of world-wide distribution, where it attacks 

 structural wood work and timbers. It has been so long associated as 

 a destructive agent with the structural wood work of men, that it was 

 supposed to be an entirely domesticated form and not known to exist 

 in the wild form. Recent investigations have shown that it occurs on 

 living trees, which when used for structural purposes furnish wood 

 which is liable to destruction later on. The mycelium of Merulius 

 lacrymans (Fig. 88), usually gains access to dressed boards, joists, or 



Fig. 88. — Immature fruiting stage of dry-rot fungus {Merulius lacrymans) de- 

 veloping on the front of a board. {After Clinton, G. P., Rep. Conn. Agric. Exper, 

 Slat., pi. xxviii, 1906.) 



rafters by the germination of one of its spores at a point where the beam 

 may be in contact with a damp wall. Its mycehum penetrates the wood 

 and usually grows lengthwise at first, the water for its extension being 

 supplied by larger more tube-like hyphae known as the conductive hyphte, 

 which carry water to the extreme end of the mycelial growth. The pres- 

 ence of the fungus results in a decay of the wood, which is reduced to a 

 brown punky mass, that crumbles between the fingers. When the myce- 

 lium comes to the surface of the wood, it forms a white felt-like coyering 

 studded with water drops, hence the specific name lacrymans referring 

 IS 



