e is faster in the soft woods or softer
portions of a wood.

Timbers seriously attacked by marine borers are badly weakened
or completely destroyed. If the original strength of the
material is to be preserved it is necessary to protect the wood
from the borers. This is sometimes accomplished by proper
injection of creosote oil, and more or less successfully by the
use of various kinds of external coatings.[38] No treatment,
however, has proved entirely satisfactory.

[Footnote 38: See Smith, C. Stowell: Preservation of piling
against marine wood borers. Cir. 128, U.S. Forest Service, 1908,
pp. 15.]

FUNGOUS INJURIES[39]

[Footnote 39: See Von Schrenck, H.: The decay of timber and
methods of preventing it. Bul. 14, U.S. Bu. Plant Industry,
Washington, D.C., 1902. Also Buls. 32, 114, 214, 266.

Meineoke, E.P.: Forest tree diseases common in California and
Nevada, U.S. Forest Service, Washington, D.C., 1914.

Hartig, R.: The diseases of trees. London and New York, 1894.]

Fungi are responsible for almost all decay of wood. So far as
known, all decay is produced by living organisms, either fungi
or bacteria. Some species attack living trees, sometimes killing
them, or making them hollow, or in the case of pecky cypress and
incense cedar filling the wood with galleries like those of
boring insects. A much larger variety work only in felled or
dead wood, even after it is placed in buildings or manufactured
articles. In any case the process of destruction is the same.
The mycelial threads penetrate the walls of the cells in search
of food, which they find either in the cell contents (starches,
sugars, etc.), or in the cell wall itself. The breaking down of
the cell walls through the chemical action of so-called
"enzymes" secreted by the fungi follows, and the eventual
product is a rotten, moist substance crumbling readily under the
slightest pressure. Some species remove the ligneous matter and
leave almost pure cellulose, which is white, like cotton; others
dissolve the cellulose, leaving a brittle, dark brown mass of
ligno-cellulose. Fungi (such as the bluing fungus) which merely
stain wood usually do not affect its mechanical properties
unless the attacks are excessive.

It is evident, then, that the action of rot-causing fungi is to
decrease the strength of wood, rendering it unsound, brittle,
and dangerous to use. The most dangerous kinds are the so-called
"dry-rot" fungi which work in many kinds of lum