A STUDY OF HEART-ROT IN WESTERN HEMLOCK. DA 
more liable to insect and fungus attack. An old tree has many 
vulnerable points, such as old branches and wounds,” and naturally 
these injuries open the tree to more-and greater infections. Hartig 1 
does not believe that old age is a natural inherent condition, but says: 
“Tn itself, the feebleness of old age is not a natural condition attribu- 
table to internal causes. The older a tree is, so much the more 
numerous are the dangers through which it has had to pass, and so 
much the greater is the number of its injuries and wounds through 
which parasites and saprophytes can find an entrance into its inte- 
QLGARLE OF 1VICRY 
PLR SOTRLES 
OL GHEE OF LNFECFION 
LACK OF WEOR 
TOTAL VOL. CUFT 
VOL ROT-CU FT 
POT, PLROENT. 
NO.OF. SPOROPHORES. 
QDGH-INCHES 
CROWN RATING 
XOXN 
Fic. 12.—Diagram showing the relation of various factors to the age classes of western hemlock on plats 
of the southwestern-slope type. 
rior.” From the data secured by questions sent to a large number 
of lumbermen in the Northwest, it was found that a majority of the 
answers received indicated that the older age classes of hemlock were 
very much more defective than the younger. Méller? has shown 
that, with the increase of age in stands infected with Trametes pini, 
there was a corresponding increase in the percentage of trees infected, 
and the data given in Table III and figures 11 and 12 also show 
plainly that with increasing age there is a definite increase in the 
amount of decay. 
1 Hartig, R. Textbook of the Diseases of Trees. Translated by William Somerville, p. 7. London 
and New York, 1894. 
2 Moller, A. Uber die Notwendigkeit und Moéglichkeit wirksamer Bekiimpfung des Kiefernbaum- 
schwammes Trametes pini (Thore) Fries. In Ztschr. Forst. u. Jagdw., Jahrg. 36, Heft 11, p. 677-715, 
2pl. (partly col.). 1904. 
