53^ 



CONSERVATION 



cement is put in and tamped into place ; 

 and after it has set sufficiently, it is 

 shaped in such a manner as to preserve 

 the contour of the tree, and permit the 

 bark to heal entirely over it. In some 

 cases the extra precaution is taken of 

 placing a zinc cap over the cement, fit- 

 ting it inside the edges of the bark. 



The thoroughness of this method is 

 at once apparent, and the thousands of 

 trees which have been thus treated bear 



which, though less expensive, was only 

 a temporary makeshift, quickly corrod- 

 ing and tearing loose from the tree as 

 it swayed in the wind, and leaving the 

 cavity open and unprotected as before. 

 Think of a dentist simply placing a 

 piece of tin over an unfilled cavity in a 

 tooth ! 



It was once thought impossible to 

 render the filling of a cavity perma- 

 nent and effective ; this idea was based 



THE RESULT OF NEGLECT 

 Weak, Unsupported Crotches Are Dangerous. Loss of Branch Destroys Symmetry and Beauty of Tree 



eloquent testimony to its effectiveness. 

 How striking, then, is the analogy be- 

 tween this method of treating a cavity 

 and the modern system of dentistry ; 

 both are based on the same three prin- 

 ciples ; the decayed matter must be en- 

 tirely removed ; the cavity must be pre- 

 pared in such a manner that the filling 

 will stay permanently in place ; and 

 moisture and all foreign substances 

 must be absolutely excluded. This 

 method is a striking improvement over 

 the antiquated system of merely clean- 

 ing out a cavity superficially, and tack- 

 ing over the outside a piece of tin, 



on the supposition that the growth of 

 a tree was on the inside, and that in 

 consequence the cement would event- 

 ually be forced out. But as a matter of 

 fact there is absolutely no growth on 

 the inside of a tree, which acts as a 

 physical support. The entire growth 

 takes place immediately under the bark, 

 and if the filling is properly put in, so 

 that it is entirely inside the growing 

 tissues, the bark will heal completely 

 over it, eventually encasing it within 

 the body of the tree. 



Another very common trouble which 

 the tree surgeon meets in his work is 



