A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 35 
A pathological survey of sales areas made with the object in view 
of determining the best method of incorporating sanitation clauses 
or of establishing pathological cutting ages would be an important 
step toward a practical and effective means of reducing the, total 
amount of good timber going to waste every year in our forests. 
Girdling by the ax as a method of removal of infected trees left 
_ standing on a sale area is not to be recommended as an effective 
means of control. If the situation allows of no better method, then 
the girdling should proceed, the utmost care being exercised in 
severing all the transporting tissues. The recuperative ability of 
hemlock in regard to the healing of wounds is very great (fig. 13). 
Merely cutting a cleft in the outer sapwood, leaving the chip in 
Fie. 13.—Cross sections of grand fir (at left) and western hemlock (at right), showing the result ofimperfect 
girdling by the use ofan ax. 
place, will not suffice. The wound is very apt to heal, and even if 
it does not the tree may continue to live for years because the trans- 
porting tissues have not been actually severed. It is to be remem- 
bered that the wood of hemlock, owing to its nonresinous nature, 
probably retains its ability to conduct water and food substances 
longer than that of many of its associates; hence it will be found 
necessary to insist upon thorough girdling. Some notable instances 
of the longevity of even thoroughly girdled hemlocks and firs have 
come to notice. in which the trees continued to live for five to eight 
years although the bark and part of the wood had been removed 
entirely around the tree for a foot or more. Trees under the shock 
of this wounding will sometimes produce as much seed in the year 
following as during several years of normal life. This point is im-. 
