tematic
manner, we see at first a guidance by conspicuous and simple
characters, and a tendency toward arrangement in linear order. In
successively later attempts, we see more regard paid to combinations
of character which are essential but often inconspicuous; and a
gradual abandonment of a linear arrangement."--_Herbert Spencer._

On one of the shelves in a certain museum lie two small boxes filled
with earth. A low mountain in Arran has furnished the first; the
contents of the second came from the Island of Barbadoes. When examined
with a pocket lens, the Arran earth is found to be full of small
objects, clear as crystal, fashioned by some mysterious geometry into
forms of exquisite symmetry. The substance is silica, a natural glass;
and the prevailing shape is a six-sided prism capped at either end by
little pyramids modeled with consummate grace.

When the second specimen is examined, the revelation is, if possible,
more surprising. Here, also, is a vast assemblage of small glassy or
porcelaneous objects built up into curious forms. The material,
chemically, remains the same, but the angles of pyramid and prism have
given place to curved lines, so that the contour is entirely different.
The appearance is that of a vast collection of microscopic urns,
goblets, and vases, each richly ornamented with small sculptured discs
or perforations which are disposed over the pure white surface in
regular belts and rows. Each tiny urn is chiseled into the most
faultless proportion, and the whole presents a vision of magic beauty.

Judged by the standard of their loveliness there is little to choose
between these two sets of objects. Yet there is one cardinal difference
between them. They belong to different worlds. The last belong to the
living world, the former to the dead. The first are crystals, the last
are shells.

No power on earth can make these little urns of the _Polycystina_ except
Life. We can melt them down in the laboratory, but no ingenuity of
chemistry can reproduce their sculptured forms. We are sure that Life
has formed them, however, for tiny creatures allied to those which made
the Barbadoes' earth are living still, fashioning their fairy palaces of
flint in the same mysterious way. On the other hand, chemistry has no
difficulty in making these crystals. We can melt down this Arran earth
and reproduce the pyramids and prisms in endless numbers. Nay, if we do
melt it down, we cannot h