6 PRACTICAL TREE REPAIR 



important effect on the choice of materials for 

 filling. Timber trees obviously must not be filled 

 with anything which cannot be sawed or chopped 

 through. Pontey doubtless meant his dry sand 

 to be drained out before the log was sawed. It is 

 doubtful if Des Cars' method can be improved on 

 for timber trees. When, however, in this country, 

 the increase of wealth in the latter part of the last 

 century greatly increased the value of shade trees, 

 these restrictions were removed. Large holes 

 were filled oftener than small ones, and men 

 naturally began to fill up holes in trees, just as they 

 would fill up a hole in a wall, with the only strong 

 material ready at hand which could be fitted to an 

 irregular shape that is, with bricks and mortar 

 or with concrete. Thus logically grew up the 

 modern system of filling with concrete, a material 

 which is just now being displaced, in part at least, 

 by asphalt. 



The present condition of the " tree surgery " 

 business is in many respects unfortunate. In the 

 first place a large part of the men who practise it 

 in a small way have not the least idea of the 

 structure of trees, the nature of decay, or the cor- 

 rect principles of treatment. They claim that 

 every filling will soon be grown over, and yet they 

 build out their concrete fillings so far that no callus 

 can form over them. They paint cavities with 

 tar to keep out the spores of fungi (or " germs," 



