CHAPTEK X 



CAUSES OF DECAY AND DESTRUCTION OF TIMBER 



Decay Caused by Bacteria and Fungi All Timber Liable to Attack 

 Propagation of Disease Conditions for Decay- Timber in Certain 

 Situations Practically Indestructible Harder and Denser Woods 

 Less Liable to Decay Animals which Destroy Timber in Sea 

 Water The Teredo Navalis Limnoria Terebrans Chelura 

 Terebrans The Sphseroma The Pholas All Timbers with Few 

 Exceptions Liable to Attack The White Ant. 



THE changes which take place in the structure of wood 

 and cause decay are due to the activity of the lower 

 forms of plant life, bacteria and fungi, chiefly the latter. 



Fungi induce changes in the organic matter of the wood, 

 by withdrawing certain substances from it on which they 

 feed, and the term " decay of timber " is now understood 

 to mean a breaking down of the complex chemical com- 

 pounds which it contains into much simpler ones, due to 

 the activity of these lower organisms which excrete 

 ferments ; these dissolve out certain parts of the walls of 

 the cells of the wood and, by so doing, destroy their 

 physical and chemical properties. 



The cells which make up the heartwood of a tree con- 

 tain no living substance. The sap is the life of the tree, 

 and is confined to the outer layers. It is composed of 

 water holding in solution various organic substances- 

 sugars, starches, oils, etc. and their presence is the cause 



