88 PRACTICAL TREE REPAIR 



If a cavity develops where the bark has been 

 wounded, the callus has no support, and as it 

 grows it does not bridge over the cavity, but simply 

 rolls inward, gradually becoming a great fold. 

 Insomuch as the fold increases, like other wood, 

 by annual layers, it is easy to count or estimate, 

 in a cross-section through such a fold, the number 

 of years since the tree became hollow. Folds of 

 this kind are not infrequently found to be half a 

 century old, or even a century. 



We can even look at the teeth, so to speak, of 

 of the rot-producing fungi themselves. Many of 

 these fungi have a woody fruiting body, or sporo- 

 phore, which adds to itself each year a new layer 

 of spore-bearing tubes. The number of layers 

 therefore indicates the age of the sporophore. 

 The hoof fungus Fomes igniarius, is such a one. 

 Sporophores of the hoof fungus have been found 

 which contained eighty annual layers. And it 

 must not be forgotten that the fungus may have 

 lived in the tree many years before it produced a 

 sporophore. 



All these facts, taken together, conclusively 

 demonstrate that the decay of trees is sometimes 

 an extremely slow process, and all indications 

 point to the conclusion that it is normally such. 



" But," it may be objected, " tuberculosis is 

 often a very slow disease. Is that, then, any 

 reason for not trying to cure it?" Not by any 



