DRY-ROT OF INCENSE CEDAR. 17 
decay collected on incense cedar in Oregon. As far as the writer can 
ascertain, this is the only collection of its kind now known. Neither 
of these two decays affects the living sapwood. 
The mycelium of both is the same and differs from the mycelium 
of typical dry-rot. Studies were made where these two decays were 
distinct, where they graded into one another, and where they graded 
into the typical dry-rot. The hyphae vary from hyaline to dark 
brown in color, with a diameter ranging from 0.8 to 6.7 fx but most 
commonly 3 ii. The heavier brown hyphae often branch profusely, 
the branches becoming smaller and lighter in color. The smallest 
ones are usually hyaline, and so are some of the larger Iryphse. In 
some instances the smaller hyphae are merely continuations of the 
heavier strands. The hyphae are sparsely septate, often constricted 
at the septa and without clamp connections. They bore through the 
cell walls in all directions, but seemingly more often through the 
tangential walls . No preference is shown for the bordered pits . They 
are characteristically sharply constricted when passing through the 
walls of the tracheids and have marked attachment organs. The 
hyphse did not enlarge in the secondary lamellae when boring through 
the wall, as is shown by Hartig (8, 9) for Trametes pini. Quite typi- 
cally, a single strand may pass tangentially through as many as 20 
or 30 tracheids, often completely traversing an annual ring, without 
sending any side branches into the lumens. This mycelium appears 
to agree closely with that described and figured by Von Schrenk 
(26, pp. 73-74, pis. 4-5), but which he assumed to be secondary and 
in no way connected with the dry-rot. Often the hyphse seem to 
pierce a cell wall without developing in the lumen of the tracheid 
entered, a condition recorded by Hartig (8, p. 46) for Trametes pini. 
However, in so many cases unattached fragments of hyphae were 
found in tracheids through the walls of which the hyphae had pene- 
trated without developing in the lumen that most probably the hyphae 
did develop but were broken off in sectioning. 
In all, 80 trees which contained one or both of these decays were 
dissected. The Trametes pini decay occurred alone in 61 of these, 
the dry-rot in small pockets in 11, and both forms in 8 trees. In 28 
of the 61 trees having the Trametes pini decay, this was either inter- 
mingled, graded into, or very close to pockets of typical decay without 
there being any line of demarcation between the two. In certain 
cases the two decays could be absolutely traced to the same source of 
infection. Tree No. 40 on the intermediate area forms an excellent 
example. This tree had two small open fire scars in the butt just at 
ground level. There was a light infection of typical pockets of dry-rot 
extending from ground level to a height of 7.3 feet. At this point 
Trametes pini decay appeared without any line of demarcation and 
182803°— 20— Bull. 871 3 
