142 HEART-ROT CAUSED BY OTHER FUNGI 
and are usually the entire width of an annual ring. The 
subsequent stages of rot are somewhat variable. The 
delignified walls of the white flecks may crumble away, 
owing to the digestion of the middle lamellae, leaving holes 
arranged in layers associated with definite annual rings, 
and if many adjacent annual rings are attacked the wood 
becomes honeycombed. This is general in the pine and 
spruce and sometimes occurs in the larch. In the Tamarack 
(Larix americana) it generally happens that the flecks become 
joined, first longitudinally and later tangentially, so that 
entire tangential sheets become rotted and intermediate 
plates can readily be separated out. In the larch and pine 
the mycelium is said not to destroy the sap-wood, so that the 
water-supply of the upper part of the tree is not materially 
reduced ; if a tree is killed by the fungus it is generally 
through wind-break at the weakened portion. For the 
same reason fructifications are not borne except on or near 
the branch stubs. In the spruce and silver fir, which are 
poorer in resin, the mycelium can penetrate to the cortex, 
and where this occurs brackets may grow from the bark 
without any special relation to the branches. 
The only remedial measure is to cut down the trees and 
destroy infected portions. As the rot is generally confined 
to the upper portions of nearly mature trees, the lower part 
of the trunk can be utilized, and it is to the forester’s interest 
to secure this timber at the earliest possible moment, as the 
longer he leaves the tree the greater will be his loss through 
the downward spread of the rot. But what is much more 
important than his own interest is his clear duty to British 
forestry. The fungus is as yet uncommon in Britain, and 
we should do all in our power to prevent it from spreading. 
Wherever any sign of its presence becomes apparent, 
infected trees should be immediately cut down, and every 
part of a tree that shows the least trace of rot should be burnt. 
To remove the brackets and incrustations is not enough, as 
they grow again even from felled logs in the forest, and it 
is impossible to maintain a sufficiently careful scrutiny to 
prevent the dissemination of the fungus. 
