of the sea-turtle under the
water,--the leaping and swimming of the frog,--the swift run of the
lizard, like a flash of green or red light in the sunshine,--the lateral
undulation of the serpent,--the dart of the pickerel,--the leap of the
trout,--the rush of the hawk-moth through the air,--the fluttering
flight of the butterfly,--the quivering poise of the humming-bird,--the
arrow-like shooting of the squid through the water,--the slow crawling
of the snail on the land,--the sideway movement of the sand-crab,--the
backward walk of the crawfish,--the almost imperceptible gliding of the
sea-anemone over the rock,--the graceful, rapid motion of the
_Pleurobrachia_, with its endless change of curve and spiral. In short,
every family of animals has its characteristic action and its peculiar
voice; and yet so little is this endless variety of rhythm and cadence
both of motion and sound in the organic world understood, that we lack
words to express one-half its richness and beauty.

FORMATION OF CORAL REEFS

From 'Methods of Study in Natural History'

For a long time it was supposed that the reef-builders inhabited very
deep waters; for they were sometimes brought up upon sounding-lines from
a depth of many hundreds or even thousands of feet, and it was taken for
granted that they must have had their home where they were found: but
the facts recently ascertained respecting the subsidence of
ocean-bottoms have shown that the foundation of a coral-wall may have
sunk far below the place where it was laid. And it is now proved, beyond
a doubt, that no reef-building coral can thrive at a depth of more than
fifteen fathoms, though corals of other kinds occur far lower, and that
the dead reef-corals, sometimes brought to the surface from much greater
depths, are only broken fragments of some reef that has subsided with
the bottom on which it was growing. But though fifteen fathoms is the
maximum depth at which any reef-builder can prosper, there are many
which will not sustain even that degree of pressure; and this fact has,
as we shall see, an important influence on the structure of the reef.

Imagine now a sloping shore on some tropical coast descending gradually
below the surface of the sea. Upon that slope, at a depth of from ten to
twelve or fifteen fathoms, and two or three or more miles from the
mainland, according to the shelving of the shore, we will suppose that
one of those little coral animals, to whom a home in suc