it a mere dream in the night of the intricate, an
abstract riddle flung out for our understanding to browse upon?

No, it is a reality in the service of life, a method of construction
frequently employed in animal architecture. The Mollusc, in particular,
never rolls the winding ramp of the shell without reference to the
scientific curve. The first-born of the species knew it and put it into
practice; it was as perfect in the dawn of creation as it can be to-day.

Let us study, in this connection, the Ammonites, those venerable relics
of what was once the highest expression of living things, at the time
when the solid land was taking shape from the oceanic ooze. Cut and
polished length-wise, the fossil shows a magnificent logarithmic spiral,
the general pattern of the dwelling which was a pearl palace, with
numerous chambers traversed by a siphuncular corridor.

To this day, the last representative of the Cephalopoda with partitioned
shells, the Nautilus of the Southern Seas, remains faithful to the
ancient design; it has not improved upon its distant predecessors. It
has altered the position of the siphuncle, has placed it in the centre
instead of leaving it on the back, but it still whirls its spiral
logarithmically as did the Ammonites in the earliest ages of the world's
existence.

And let us not run away with the idea that these princes of the Mollusc
tribe have a monopoly of the scientific curve. In the stagnant waters of
our grassy ditches, the flat shells, the humble Planorbes, sometimes no
bigger than a duckweed, vie with the Ammonite and the Nautilus in matters
of higher geometry. At least one of them, _Planorbis vortex_, for
example, is a marvel of logarithmic whorls.

In the long-shaped shells, the structure becomes more complex, though
remaining subject to the same fundamental laws. I have before my eyes
some species of the genus Terebra, from New Caledonia. They are
extremely tapering cones, attaining almost nine inches in length. Their
surface is smooth and quite plain, without any of the usual ornaments,
such as furrows, knots or strings of pearls. The spiral edifice is
superb, graced with its own simplicity alone. I count a score of whorls
which gradually decrease until they vanish in the delicate point. They
are edged with a fine groove.

I take a pencil and draw a rough generating line to this cone; and,
relying merely on the evidence of my eyes, which are more or less
practised in g