172 MASS. EXPERIMENT STATION BULLETIN 170. 



substance should be one which can safely be used and still be permanently 

 effective. Creosote is one of the best antiseptics because it possesses 

 superior properties for penetrating wood, and is 

 quite permanent as a disinfectant. In some cavity 

 work this is as far as it is necessary to proceed, 

 especially in the treatment of old, weak, decrepit 

 trees which at most have only a brief period to 

 live, and when there is already considerable 

 strengthening tissue owing to the inward growth 

 of the callus and wood. It is often inadvisable to 

 I'emove this strengthening tissue and fill the cavity. 

 (See Fig. 43.) 



Third, to cover the orifice or opening of the 

 cavity to direct the growth of the callus or healing 

 tissue. However, trees are seldom if ever strength- 

 ened by fillings; on the other hand, they are too 

 often weakened by overloading, although ulti- 

 mately, as new tissue develops over the surface of 

 the filling, strengthening ma}^ follow as a result 

 of growth. 



Innumerable instances may be observed of 

 positively injurious tree repair work which has 

 been done by incompetent men, some of whom 

 are downright scoundrels; and many trees have 

 come to a sad end from overloading with heavy 

 concrete. Sometimes the tree collapses 

 before the contractor actually finishes the 

 work, in which case litigation usually 

 follows. 



The wiiter has had many opportunities 

 to observe cavity work in trees. Some of 

 these cavities were treated forty years 

 ago, and when thorough cleaning and 

 antiseptic treatment were given the cav- 

 ities, decay has been arrested to a very 

 remarkable extent. Even some of the 

 work done by ignorant men (jnd am- 

 ateurs, who are unable to distinguish 

 between normal and infected wood, has 

 been effective in arresting decay, although 

 only the punk and discolored tissue is 

 usually removed from the cavities. 



AVhile some progress has been made in 

 cavity treatment during recent years, the greatest drawback to the de- 

 velopment of a more scientific and intelligent method of treatment is 

 ignorance and incompetency on the part of those undertaking such 



Fig. 36. — Showing 

 relative strain in 

 pounds on wire 

 or chain holding 

 limbs at different 

 angles. The strain 

 at X would be twice 

 as much as at a. 



Fig. 37.— Illustrating a faulty 

 method of chaining trees. 



