DECAY OF THE ‘BLUE’ WOOD. a 
After the wood has been dead for some time certain changes begin, 
which in the end result in the entire decay of the wood. The dead 
wood may or may not be blue, for the processes by which the wood 
changes to decayed wood are the same for wood which is entirely 
healthy and for the ** blue” wood. 
THE **RED ROT” OF THE WESTERN YELLOW PINE. 
The **red rot” of the western yellow pine usually starts in the tops of 
the ‘* black-top” trees, i. e., trees which have been dead for two or more 
years. At one or more points, usually on the north or east side of a tree, 
one will find that the wood immediately under the bark starts to rot. 
This rot starts at the bark and gradually extends inward (Pl. X, tig. 1). 
The wood when it shows the first signs of this decay is wet and soggy 
and rapidly becomes brittle, so that it crumbles into small pieces when 
rubbed. A plane will no longer make a smooth surface (Pl. X. figs. 1 
and 2), for the knife tears out small pieces of the wood fiber. The 
color of the wood changes from blue to red yellow. When the decay 
has gone on for some time, bands and sheets of a white felty substance 
are found filling certain cracks which result because of shrinkage in 
the wood mass (PI. X, fig. 2). These white sheets consist of masses of 
fungus threads densely interwoven. The destruction of the wood con- 
tinues until the heartwood is reached, and as this is exceedingly small 
in the tops of these trees one will find that after some time almost 
the entire wood mass has changed to a brown, brittle, resistless mass 
(Pl. XI). The completely rotted wood crumbles into a fine powder 
when crushed between the fingers. When wet it is of a cheesy con- 
sistency. When the water has evaporated from such wood it is like 
so much brown charcoal. 
CAUSE OF THE ‘**RED ROT.” 
The **red rot” of the dead timber is caused by one of the higher 
fungi which grows in the wood, and by so doing brings about the decay 
of the wood. The spores of this fungus fly about in the forest and 
some of them lodge in bark crevices of the dying trees. The numerous 
beetle holes afford every opportunity for entrance to the wood, and it 
is therefore not surprising to find that the majority of the ** black-top” 
trees become infected sooner or later with the spores of this fungus. 
The spores germinate and hyphe grow into the dead cambium and the 
wood, where they attack such organic matter as has been left by the 
**blue” fungus. They go farther, however, and attack the cell walls 
of the wood fibers, from which they extract the cellulose. As a 
result of this, the wood fibers shrink in volume and crack in regular 
lines extending obliquely across the cell walls. As the solution of the 
