mooth
before the coal tar is applied. Loose bark, put back against a tree,
will never grow and will only tend to harbor insects and disease.
Bandages, too, are hurtful because, underneath the bandage, disease
will develop more rapidly than where the wound is exposed to the sun
and wind. The application of tin or manure to wounds is often
indulged in and is equally injurious to the tree. The secret of all
wound treatment is to keep the wound _smooth, clean_ to the live
tissue, _and well covered_ with coal tar.

The chisel or gouge is the best tool to employ in this work. A sharp
hawk-billed knife will be useful in cutting off the loose bark. Coal
tar is the best material for covering wounds because it has both an
antiseptic and a protective effect on the wood tissue. Paint, which
is very often used as a substitute for coal tar, is not as
effective, because the paint is apt to peel in time, thus allowing
moisture and disease to enter the crevice between the paint and the
wood.

[Illustration: FIG. 117.--A Neglected Surface Wound. Note the rough
surface of the wound, the want of a coal tar covering and the fungous
growth that followed.]

Cavities: Deep wounds and cavities are generally the result of stubs
that have been permitted to rot and fall out. Surface wounds allowed
to decay will deepen in course of time and produce cavities.
Cavities in trees are especially susceptible to the attack of
disease because, in a cavity, there is bound to exist an
accumulation of moisture. With this, there is also considerable
darkness and protection from wind and cold, and these are all ideal
conditions for the development of disease.

The successful application of a remedy, in all cavity treatment,
hinges on this principal condition--_that all traces of disease
shall be entirely eliminated before treatment is commenced_.

Fungous diseases attacking a cavity produce a mass of fibers, known
as the "mycelium," that penetrate the body of the tree or limb on
which the cavity is located. In eliminating disease from a cavity,
it is, therefore, essential to go _beyond_ the mere decaying surface
and to cut out all fungous fibers that radiate into the interior of
the tree. Where these fibers have penetrated so deeply that it
becomes impossible to remove every one of them, the tree or limb
thus affected had