s, producing different results from the same
motives or elements. Much of the diversity displayed by the art products
of different countries and climates is due to this cause.

Peoples dwelling in arctic climates are limited, by their materials, to
particular modes of expression. Bone and ivory as shaped for use in the
arts of subsistence afford facilities for the employment of a very
restricted class of linear decoration, such chiefly as could be
scratched with a hard point upon small irregular, often cylindrical,
implements. Skins and other animal tissues are not favorable to the
development of ornament, and the textile arts--the greatest agents of
convention--do not readily find suitable materials in which to work.

Decorative art carried to a high stage under arctic environment would be
more likely to achieve unconventional and realistic forms than if
developed in more highly favored countries. The accurate geometric and
linear patterns would hardly arise.

_Through form._--Forms of decorated objects exercise a strong influence
upon the decorative designs employed. It would be more difficult to
tattoo the human face or body with straight lines or rectilinear
patterns than with curved ones. An ornament applied originally to a
vessel of a given form would accommodate itself to that form pretty much
as costume becomes adjusted to the individual. When it came to be
required for another form of vessel, very decided changes might be
necessary.

With the ancient Pueblo peoples rectilinear forms of meander patterns
were very much in favor and many earthen vessels are found in which
bands of beautiful angular geometric figures occupy the peripheral
zone, Fig. 480 _a_, but when the artist takes up a mug having a row of
hemispherical nodes about the body, _b_, he finds it very difficult to
apply his favorite forms and is almost compelled to run spiral curves
about the nodes in order to secure a neat adjustment.

[Illustration: FIG. 480.--Variations in a motive through the influence
of form.]

_Through methods of realisation_.--It will readily be seen that the
forms assumed by a motive depend greatly upon the character of the
mechanical devices employed. In the potter's art devices for holding and
turning the vessel under manipulation produce peculiar results.

In applying a given idea to clay much depends upon the method of
executing it. It will take widely differing forms when executed by
incising, by modeling, by pai