14 BULLETIN 722, 1^. S. DEPARTMENT OF AaRTCULTURE. 



appearance relative to environment, etc., were recorded. Each 

 tree was designated by a number. Altogether, 201 trees of western 

 hemlock were cut on the ten areas, and about an equal number of 

 grand fir. The hemlocks considered in this study arc numbered from 

 1 to 201. No selection of trees was practiced, but all trees on the 

 areas laid out were cut. 



Aside from a few cases of secondary decay, the cause of which 

 could not be definitely determined from a chemical and anatomical 

 study of the rot alone, the occurrence on hemlock of the more common 

 fungi of the associated species was practically nil. In a few cases 

 the rot of Trametes pini and Polyporus schweinitzii was found in 

 hemlock, but since the merchantable parts of the same trees were 

 wholly decayed by EcJiinodontium tinctorium, all decay of the species 

 on the areas is attributed to the latter. This is equivalent to saying 

 that practically 100 per cent of all cases of decay in living hemlock 

 were due to E. tinctorium. This is by no means an unusual condition 

 for the region. In fact, the finding of any other fungus working as a 

 first agent of decay in hemlock is a rarity. 



METHODS USED IN PRESENTING DATA. 



The methods used in preparing the data for presentation and com- 

 parison are the result of an attempt at standardizing such factors 

 as, in ordinary field observations, are usually determined by an 

 ocular method not involving exact measurements. Any attempt at 

 standardization of such factors as are included under ' ' Seriousness of 

 injury," ''Degree of vigor/' or "Crown rating" is bound to meet with 

 difficulties. So long as the same standard is used consistently 

 throughout the work, a slight amount of arbitrary standardization 

 will not in the least reduce the value of the results. 



The total volume of the tree, less the stump, inside of the bark was 

 first secured in cubic feet by means of the paraboloid formula,^ 

 V= (BH-^2), and the table of basal areas." The diameter (inside of 

 the bark) at the stump was used to secure the above figure. The 

 total volume of rot in the tree, less the stump, was secured in cubic 

 feet by a similar method. As an experiment to determine the shape 

 of the rot column, the outlines of the rot column of several infected 

 hemlocks were plotted on coordinate paper. It was found that 

 these rot outlines conformed closely to the general outlines of the 

 trees. It was also found that the formula used to secure the volume 

 of rot more nearly included all the rot found within the trunk than 

 did the Smalian method. The dissection of the trees and the plotting 

 of a few of them on coordinate paper showed that the formula as 



1 Graves, H. S. Forest Mensuration, ed. 1, p. 88. New York, London, 1900. 

 « Graves, H. S. Op. eiti, p. 430. 



