FILLING TREES 89 



means, but it is a very good reason for not too 

 hastily concluding that the disease is cured by 

 a certain treatment, just because the patient sur- 

 vives that treatment for a year or two. And 

 that is just the point. The tree surgeons, if we 

 express doubts as to the effectiveness of their work, 

 will show us examples of it which are eight or ten 

 years old, and ask if any further proof is neces- 

 sary. It surely is. We must be convinced that 

 the tree would not now be in as good condition 

 as it is if the filling had not been put in. That, 

 of course, is not an easy thing to do, because no 

 two trees are alike, and because of the impossibil- 

 ity of seeing what is going on inside of a filled 

 tree. No definite conclusion can be arrived at as 

 to the effectiveness of large fillings in decayed 

 trees until impartial observers have studied a large 

 number of filled and unfilled trees for a long period 

 of years. This conclusion obviously works both 

 ways. If it will take a long time to prove that 

 filling trees works, so will it take a long time to 

 prove that it doesn't work, and the only way to 

 learn is to try. With this the writer agrees per- 

 fectly, because it is an admission of his thesis, that 

 tree surgery is still in an experimental stage. 



There is one aspect of the filling of trees, how- 

 ever, about which doubt no longer exists, and that 

 is its expensiveness. It requires a great deal of 

 hard as well as skilled labor to remove the decayed 



