Discourses: Biological and Geological Essays | Page 8

living Globigerinoe
are exclusively marine animals, the skeletons of which abound at the
bottom of deep seas; and that there is not a shadow of reason for
believing that the habits of the Globigerinoe of the chalk differed from
those of the existing species. But if this be true, there is no escaping the
conclusion that the chalk itself is the dried mud of an ancient deep sea.
In working over the soundings collected by Captain Dayman, I was
surprised to find that many of what I have called the "granules" of that
mud were not, as one might have been tempted to think at first, the
more powder and waste of Globigerinoe, but that they had a definite
form and size. I termed these bodies "coccoliths," and doubted their
organic nature. Dr. Wallich verified my observation, and added the
interesting discovery that, not unfrequently, bodies similar to these
"coccoliths" were aggregated together into spheroids, which lie termed
"coccospheres." So far as we knew, these bodies, the nature of which is
extremely puzzling and problematical, were peculiar to the Atlantic
soundings. But, a few years ago, Mr. Sorby, in making a careful

examination of the chalk by means of thin sections and otherwise,
observed, as Ehrenberg had done before him, that much of its granular
basis possesses a definite form. Comparing these formed particles with
those in the Atlantic soundings, he found the two to be identical; and
thus proved that the chalk, like the surroundings, contains these
mysterious coccoliths and coccospheres. Here was a further and most
interesting confirmation, from internal evidence, of the essential
identity of the chalk with modern deep-sea mud. Globigerinoe,
coccoliths, and coccospheres are found as the chief constituents of both,
and testify to the general similarity of the conditions under which both
have been formed.[3]
[Footnote 3: I have recently traced out the development of the
"coccoliths" from a diameter of 1/7000th of an inch up to their largest
size (which is about 1/1000th), and no longer doubt that they are
produced by independent organisms, which, like the Globigerinoe, live
and die at the bottom of the sea.]
The evidence furnished by the hewing, facing, and superposition of the
stones of the Pyramids, that these structures were built by men, has no
greater weight than the evidence that the chalk was built by
Globigerinoe; and the belief that those ancient pyramid-builders were
terrestrial and air-breathing creatures like ourselves, is not better based
than the conviction that the chalk-makers lived in the sea. But as our
belief in the building of the Pyramids by men is not only grounded on
the internal evidence afforded by these structures, but gathers strength
from multitudinous collateral proofs, and is clinched by the total
absence of any reason for a contrary belief; so the evidence drawn from
the Globigerinoe that the chalk is an ancient sea-bottom, is fortified by
innumerable independent lines of evidence; and our belief in the truth
of the conclusion to which all positive testimony tends, receives the
like negative justification from the fact that no other hypothesis has a
shadow of foundation.
It may be worth while briefly to consider a few of these collateral
proofs that the chalk was deposited at the bottom of the sea. The great
mass of the chalk is composed, as we have seen, of the skeletons of

Globigerinoe, and other simple organisms, imbedded in granular matter.
Here and there, however, this hardened mud of the ancient sea reveals
the remains of higher animals which have lived and died, and left their
hard parts in the mud, just as the oysters die and leave their shells
behind them, in the mud of the present seas.
There are, at the present day, certain groups of animals which are never
found in fresh waters, being unable to live anywhere but in the sea.
Such are the corals; those corallines which are called Polyzoa; those
creatures which fabricate the lamp-shells, and are called Brachiopoda;
the pearly Nautilus, and all animals allied to it; and all the forms of
sea-urchins and star-fishes. Not only are all these creatures confined to
salt water at the present day; but, so far as our records of the past go,
the conditions of their existence have been the same: hence, their
occurrence in any deposit is as strong evidence as can be obtained, that
that deposit was formed in the sea. Now the remains of animals of all
the kinds which have been enumerated, occur in the chalk, in greater or
less abundance; while not one of those forms of shell-fish which are
characteristic of fresh water has yet been observed in it.
When we consider that the remains of more than three thousand distinct
species of aquatic animals have been discovered among the fossils of
the chalk, that the