PAEASITIC 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 

 Dematium giganteum, 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 Nageli, a celebrated 



