e _sphere_ give us the fundamental elements, or primal
types from which are derived the multifarious, ever varying, and complex
forms, the products of the forces and conditions of nature, or the
necessitous inventiveness of art, just as we may take the square and the
circle to be the parents of linear and geometric design.

[Illustration (f045a): Elementary Forms: Pyramid, Sphere, Cube, Hexagon,
Cone.]

The cube and the sphere, the ellipse, the cone, and the pyramid, with
other comparatively simple forms of solid geometry, present themselves
to the student as elementary tests of draughtsmanship--of the power,
that is, of representing solid bodies upon a plane surface. Such forms
being more simple and regular than any natural forms, they are supposed
to reduce the problem of drawing to its simplest conditions. They
certainly afford very close tests of correctness of eye, making any
fault in perspective or projection at once apparent.

[Illustration (f045b): Use of Elementary Forms in Architecture.]

To avoid, however, falling into mechanical ways, and to maintain the
interest and give vitality to such studies, the relation of such forms
to forms in nature and art should be borne in mind, and no opportunity
missed of comparing them, or of seeking out their counterparts,
corresponding principles, and variations, as well as their practical
bearing, both functional and constructive; as in the case of the typical
forms of flowers, buds, and seed-vessels, for instance, where the cone
and the funnel, and the spherical, cylindrical, and tubular principles
are constantly met with, as essential parts of the characters and
organic necessities of the plant: the cone and the funnel mostly in buds
and flower-petals for protection and inclosure of the pollen and seed
germs, the tube for conducting the juices; the spherical form to resist
moisture externally, or to hold it internally, or to avoid friction, and
facilitate close storage, as in the case of seeds in pods. The
seed-vessel of the poppy, for instance, has a curious little pent-house
roof to shield the interstices (like windows in a tower) till the seed
is ripe and the time comes for it to be shaken out of the shell or pod.
A further practical reason for the prevalence of spherical form in seeds
is that they may, when the outer covering or husk perishes, more readily
roll out and fall into the interstices of the ground; or when, as in the
case of various fruits, such as the