14 BULLETIN 722, U. S. DEPARTMENT OF AGRICULTURE. 
appearance relative to environment, ete., 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 are 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 pint and Polyporus schweinitzii was found in 
hemlock, but since the merchantable parts of the same trees were 
wholly decayed by ELchinodontium 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.2. 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, 1906. 
2 Graves, H.S. Op. cit., p. 430. 
