PARASITIC FUNGI AND MOULDS. 45 
putrefaction and of these fungi. The hardest wood 
yields to the same agents, not indeed so quickly, yet 
much more rapidly than would be the case from the 
action of the constituents of the atmosphere alone. 
When a log of one of our finest trees is attacked by 
fungi, it soon becomes only a mass of rotten wood, 
of which the woody tissue has been traversed and 
destroyed by the mycelium. If the same log were 
* merely subjected to the action of the weather, it 
might endure for half a century before becoming 
completely rotten. 
Merulius destruens (or M. lacrymans) attacks 
beams and the other pieces of wood used in building, 
and rapidly destroys them. The administrators of the 
Canal du Midi, Toulouse, were compelled to replace 
the oak piles which protect the sides of the canal as 
it traverses the town, on account of the ravages of 
Dematiwm gigantewm, one of the higher orders of 
fungi in its early form. At the end of the last 
century, the same fungus destroyed, in the course of - 
two or three years, the Foudroyant, a sixty-gun 
vessel. 
In order to stop the development of these fungi in 
wood used for building, and especially in wood in- 
tended for ship-building, it is expedient, as soon as 
the trees are felled, to steep them in a metallic 
antiseptic solution—as, for instance, in sulphate of 
copper. 
An experiment made by Niageli, a celebrated 
