steadily upwards, occurred to Darwin more than thirty years
after Flinders sailed along the Reef; and what the navigator wrote was
the result of his own observation and thought. Many absurd and fanciful
speculations about coralline formation were current in his day, and have
often been repeated since. But the reader who has given any study to
Darwin's array of facts and powerful reasoning will be interested in the
ideas of the earlier observer:

"It seems to me, that, when the animalcules which form the corals at the
bottom of the ocean cease to live, their structures adhere to each other,
by virtue either of the glutinous remains within, or of some property in
salt water; and the interstices being gradually filled up with sand and
broken pieces of coral washed by the sea, which also adhere, a mass of
rock is at length formed. Future races of these animalcules erect their
habitations upon the rising bank, and die in their turn, to increase, but
principally to elevate, this monument of their wonderful labours. The
care taken to work perpendicularly in the early stages would mark a
surprising instinct in these diminutive creatures. Their wall of coral,
for the most part in situations where the winds are constant, being
arrived at the surface, affords a shelter to leeward of which their
infant colonies may be safely sent forth; and to their instructive
foresight it seems to be owing that the windward side of a reef exposed
to the open sea is generally, if not always, the highest part, and rises
almost perpendicular, sometimes from the depth of 200, and perhaps many
more fathoms. To be constantly covered with water seems necessary to the
existence of the animalcules, for they do not work, except in holes upon
the reef, beyond low-water mark; but the coral, sand, and other broken
remnants thrown up by the sea adhere to the rock, and form a solid mass
with it, as high as the common tides reach. That elevation surpassed, the
future remnants, being rarely covered, lose their adhesive property, and,
remaining in a loose state, form what is usually called a key upon the
top of the reef. The new bank is not long in being visited by sea-birds;
plants take root upon it; a cocoanut, or the drupe of a pandanus is
thrown on shore; land-birds visit it and deposit the seeds of shrubs and
trees; every high tide, and still more every gale, adds something to the
bank; the form of an island is gradually assumed; and last of all comes
man to