TREATMENT WITHOUT FILLING 181 



whether further excavation is necessary and, if so, 

 to continue it. This is easy when the filling is 

 omitted. The cavity is inspected annually, and if 

 there is any decay it can be removed. 



On the other hand it is claimed that several 

 advantages attained by the filling are lost by omit- 

 ting it. First, no provision is made for the sup- 

 port of the callus, which, without support, cannot 

 bridge the wound. Second, the provisions against 

 the entrance of insects and fungi are inadequate. 

 Third, the strengthening effect of the filling is lost. 

 Fourth, if the excavation is a large one it will in- 

 variably ruin the beauty of the trunk of the tree. 



In answer to these claims the " ultra-modern- 

 ists," to borrow a phrase from a rather remote 

 field, assert, as to the first of them, that in the 

 case of large wounds in old trees callus growth is 

 so slow as to be negligible, and that when calluses 

 do grow, they help the tree quite as much physi- 

 ologically and almost as much physically when they 

 roll into the cavity as when they bridge over it. 

 Of the second claim they say that a heavy dress- 

 ing, periodically renewed, is as good as a filling, 

 and of the third, that the strengthening effect of 

 the filling is highly problematical and cannot be 

 great in any case. As regards the esthetic argu- 

 ment, they frankly admit that they are not work- 

 ing for looks but for effectiveness. 



As to the technique of the " open system,'* but 



