section of this paper.

[Illustration: FIG. 327. Coiled tray with geometric devices, probably
modified by ideographic association. Moki work--1/4.]

[Illustration: FIG. 328. Tray of interlaced style of weaving, showing
geometric ornament, probably modified by ideographic association. Moki
work--1/4.]

The processes of pure geometric elaboration with which this section is
mainly concerned can be studied to best advantage in more primitive
forms of art.

[Illustration: FIG. 329. Tray of interlaced style of weaving, showing
geometric ornament, probably modified by ideographic association. Moki
work--1/4.]

_Non-essential constructive features._--Now, all the varied effects of
color and design described in the preceding paragraphs are obtained
without seriously modifying the simple necessary construction, without
resorting to the multiple extraordinary devices within easy reach. The
development and utilization of the latter class of resources must now
receive attention. In the preceding examples, when it was desired to
begin a figure in color the normal ground filament was dropped out and
a colored one set into its place and made to fill its office while it
remained; but we find that in many classes of work the colored
elements were added to the essential parts, not substituted for them,
although they are usually of use in perfecting the fabric by adding to
serviceability as well as to beauty. This is illustrated, for example,
by the doubling of one series or of both warp and woof, by the
introduction of pile, by wrapping filaments with strands of other
colors, or by twisting in feathers. Savage nations in all parts of the
world are acquainted with devices of this class and employ them with
great freedom. The effects produced often correspond closely to
needlework, and the materials employed are often identical in both
varieties of execution.

The following examples will serve to illustrate my meaning. The effect
seen in Fig. 330 is observed in a small hand wallet obtained in
Mexico. The fillets employed appear to be wide, flattened straws of
varied colors. In order to avoid the monotony of a plain checker
certain of the light fillets are wrapped with thin fillets of dark
tint in such a way that when woven the dark color appears in small
squares placed diagonally with the fundamental checkers. Additional
effects are produced by covering certain portions of the filaments
with straws of distinct color, all being wove