PIINGAL ATTACK 59 



already stated, an indication of at least incipient local decay. 

 Discoloured patches, such as occur on the exterior of the butt- 

 ends of some masts of the Kauri (or Cowdie) Pine of l^ew Zealand 

 {AgatUs austrdlis), will generally be found to be relatively brittle. 

 They are usually white at first and are then of small extent or 

 consequence ; but when they are yellowish-red, the mischief has 

 gone further ; and a decided red or foxy colour indicates a wide- 

 spread decay so serious as to disqualify the timber for purposes of 

 construction. Oak, however, in an advanced state of foxiness 

 and decay is in request for cabinet-work. In old Beeches, and 

 other trees, decay appears to begin in the pith and spread outwards, 

 such wood being known in France as hois rouge ; but it very fre- 

 quently originates in a broken branch, a rind-gall, or a star-shake 

 reaching the surface, so that air, damp and fungi find access to the 

 wood of the tree. It is this decay spreading from the pith that 

 gradually hollows out old trees ; but this hollowing occurs much 

 earlier in pollards where water and rotting leaves may accumulate 

 in the fork of the crown, or in trees in which broken limbs or 

 other injuries have been neglected. The breaking of a small 

 branch may set up decay, and yet such a druxy knot, as it is termed, 

 may gradually be covered up with sound wood, so that only a 

 shght swelHng may indicate the defect at the surface of the stem. 

 Any such excrescence should be removed directly a tree is felled ; as, 

 though the heahng over, by excluding further damp, may have 

 checked the mischief, there is no telling from the outside how deep 

 it may have extended, and such a patch of decayed wood, if left to 

 itself, is certain on being laid bare in the process of conversion to 

 absorb more atmospheric moisture and so enlarge itself. 



It is now clearly understood that the pure lignified cellulose of 

 •^seasoned wood is practically imperishable. It may be sphntered 

 and pulverized by mechanical action, but neither air nor moisture 

 have per se any destructive effect on it. Originally secreted by the 

 protoplasm of the vegetable cell, it is, however, liable to be re- 

 dissolved or digested by this powerful natural solvent, or, perhaps, 

 rather by the ferments which it contains. This protoplasmic 

 fermentative action may aSect wood in two ways. When wood 

 is '* green " or imperfectly seasoned, it may be set up by the 

 nitrogenous matter remaining in the tissues of the wood itself. 

 On the other hand, after seasoning, if proper ventilation is absent, 

 and if the tissues of the wood have not been refilled with some 

 preservative, it may originate in the action of the Hving protoplasm 

 of some other plant, such as a " mould " or saprophytic fungus, 

 or the cellulose-bacteria of the soil. 



Fungal attack. — ^Fungi excrete ferments, which, in the presence 



