PRUNING SHADE TREES 
i45 
surface with a coat of shellac. This should be applied 
with a brush to the edges of the wound, covering the bark 
and at least half an inch of the wood. This should be done 
as soon as the cut is dry enough to hold the shellac, and 
within three or four minutes at the most after the 
cutting. The shellac serves to prevent loss of moisture, 
and since the cambium, or inner bark, will die if it is 
allowed to dry out, the coating is an essential step. 
Wounds more than half an inch in diameter require 
artificial protection during the process of healing. This 
protection is given by painting with shellac and following 
this by coating the center of the wound with coal tar, 
creosote or lead paint. The shellac forms one of the best 
protecting covers for the sensitive tissue between the 
bark and the wood where growth takes place, and which 
is called cambium layer or cambium. It is the least 
injurious to this vital but sensitive part of the tree of all 
of the substances now known. As it is not permanent 
when exposed to weather, especially moisture, it needs 
to be coated with one of the other substances mentioned. 
The shellac need not be applied to the whole wound if the 
cambium is thoroughly covered, including an inch of the 
adjacent wood. 
If the wound is large, it'should be sterilized by applying 
antiseptic after the application of the shellac. There are 
several preparations of this nature, and among these one 
of the best is creosote, which has a particular value in 
destroying the germs of decay and preventing destruction. 
The creosote is applied with a brush and should cover all 
of the exposed wood not covered by the shellac. On top 
of the shellac and creosote the surface should then be 
covered with a thick coating of coal tar to keep out 
water. This waterproof coating should be renewed from 
year to year, whenever there is a tendency to crack or 
