cut of a knife or the careless wielding of an axe, to the boring of
an insect, or to the decay of a fungous disease. (See Fig. 117.)
Whatever the cause, _the remedy lies in cleaning out all decayed
wood, removing the loose bark and covering the exposed wood with
coal tar_.

In cutting off the loose bark, the edges should be made smooth
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