grain."

Figure in wood is effected by the way light is thrown upon it, showing
light if seen from one direction, and dark if viewed from another, as
may easily be observed by holding a piece of figured mahogany under
artificial light and looking at it from opposite directions. The
characteristic markings on mahogany are "mottle," which is also found
in sycamore, and is conspicuous on the backs of fiddles and violins,
and is not in itself valuable; it runs the transverse way of the
fibres and is probably the effect of the wind upon the tree in its
early stages of growth. "Roe," which is said to be caused by the
contortion of the woody fibres, and takes a wavy line parallel to
them, is also found in the hollow of bent stems and in the root
structure, and when combined with "mottle" is very valuable. "Dapple"
is an exaggerated form of mottle. "Thunder shake," "wind shake," or
"tornado shake" is a rupture of the fibres across the grain, which in
mahogany does not always break them; the tree swaying in the wind only
strains its fibres, and thus produces mottle in the wood.

SECTION V

ENEMIES OF WOOD

From the writer's personal investigations of this subject in different
sections of the country, the damage to forest products of various
kinds from this cause seems to be far more extensive than is generally
recognized. Allowing a loss of five per cent on the total value of the
forest products of the country, which the writer believes to be a
conservative estimate, it would amount to something over $30,000,000
annually. This loss differs from that resulting from insect damage to
natural forest resources, in that it represents more directly a loss
of money invested in material and labor. In dealing with the insects
mentioned, as with forest insects in general, the methods which yield
the best results are those which relate directly to preventing attack,
as well as those which are unattractive or unfavorable. The insects
have two objects in their attack: one is to obtain food, the other is
to prepare for the development of their broods. Different species of
insects have special periods during the season of activity (March to
November), when the adults are on the wing in search of suitable
material in which to deposit their eggs. Some species, which fly in
April, will be attracted to the trunks of recently felled pine trees
or to piles of pine sawlogs from tre