216 DISEASES OF TREES 



enclosed fungus-mycelium, the latter continues to grow in the 

 presence of moisture, and the wood is still further destroyed. 



Squared timber that has been floated suffers quite as much 

 from red-stripe as that which comes straight from the saw-mill. 

 As nowadays it hardly ever happens that perfectly dry timber 

 is employed for structural purposes, there is great danger of the 

 so-called " dry-rot " appearing in a destructive form. 



The greatest danger attaches to the ends of joists that are 

 built into a wall. If the latter contains water, it is transmitted 

 to the wood, so that joists which may have been fairly dry are 

 again rendered so wet as to enable any fungus-mycelium con- 

 tained in the cracks of the wood to develop and destroy timber 

 that was perfectly sound when placed in the building. Should 

 the ends of the joists have originally shown any appearance of 

 red-stripe, the danger of total decay is of course increased. One 

 ought therefore to endeavour, as far as possible, to avoid using 

 red-striped joists, or at least their use should be confined to the 

 highest story of a building, where the walls being thinner dry 

 faster. Under any circumstances, however, one should never 

 neglect to apply several coats of creosote (common coal-tar oil) 

 or some special carbolic preparation to the ends of the joists for 

 a distance of three feet, before they are built into the wall. Tar 

 cannot be recommended, because it does not penetrate far into 

 the wood, and it forms a covering which prevents the joists 

 from drying. 



The other parts of the joists are not so much exposed to 

 danger. Even when they are red-striped they usually dry so 

 soon in properly constructed buildings as not to suffer further 

 damage from any fungus that they may contain, though of course 

 their strength is reduced in proportion to the extent of the 

 disease. 



The name " dry-rot " is unhappily chosen, in so far that it is 

 characterized as occurring only in wet or damp wood, in which 

 the fungi can find sufficient moisture for growth. Merulius 

 lacrymans, on the other hand, may destroy perfectly dry wood 

 by imbibing and conducting the water requisite for growth from 

 other parts of the building, and either parting with it to the 

 woodwork or letting it escape in the form of drops or " tears." 

 The disease has, in fact, acquired the name " dry-rot " because it 



