174 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



which needs a chapter to itself, I may pass on to 

 more general remarks on what we have learnt so far. 

 It will be noticed that, whereas such fungi as Tra- 

 metes radiciperda and Agaricus melleus are true para- 

 sites which can attack the living roots of trees, the 

 other fungi referred to can only reach the interior of 

 the timber from the exposed surfaces of wounds. It 

 has been pointed out along what lines the special 

 treatment of the former diseases must be followed, 

 and it only remains to say of the latter : take care of 

 the cortex and cambium of the tree, and the timber 

 will take care of itself. It is unquestionably true that 

 the diseases due to wound-parasites can be avoided 

 if no open wounds are allowed to exist. Many a fine 

 oak and beech perishes before its time, or its timber 

 becomes diseased and a high wind blows the tree down, 

 because the spores of one of these fungi alight on the 

 cut or torn surface of a pruned or broken branch. Of 

 course it is not always possible to carry out the sur- 

 gical operations, so to speak, which are necessary to 

 protect a tree which has lost a limb, and in other cases 

 no doubt those responsible have to discuss whether it 

 costs more to perform the operations on a large scale 

 than to risk the timber. With these matters I have 

 nothing to do here, but the fact remains that by 

 properly closing over open wounds, and allowing the 



