252 PRACTICAL TREE REPAIR 



The wood most recently invaded can with diffi- 

 culty be distinguished from the healthy wood, 

 save that it is a trifle " short " and a bit browner. 

 Wood longer affected becomes soft, moist, and 

 sour-smelling. The center of the trunk, if the 

 decay has progressed so far, is hollow, with 

 webby masses of powdered rotten wood clinging 

 to the walls of the cavity and heaped at the bot- 

 tom. It is an extremely unsatisfactory decay to 

 excavate on account of the difficulty of determin- 

 ing where it leaves off. A compound microscope 

 would probably be the only sure arbiter. Bad 

 cases of this decay are better left alone. 



No special notes are necessary upon the treat- 

 ment of cavities in elms, except to call attention to 

 the moistness of the wood and the great desir- 

 ability of permitting cavities to dry out thoroughly 

 before dressing and filling them. When possible 

 it is very advantageous to permit the cavity to 

 stand a month or two with only a preliminary 

 dressing of some non-filling antiseptic solution 

 such as sulphate of copper or corrosive sublimate. 

 If at the end of that time the wood is dry, the 

 heavier dressings can be applied and the filling 

 put in. 



The elm is more frequently affected than any 

 other tree by the " slime-flux " which has already 

 been described, along with such preventive meas- 

 ures as are known. 



