It therefore seems to be hardly doubtful that these wonderful creatures
live and die at the depths in which they are found.
However, the important points for us are, that the living Globigerinae
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 Globigerinae 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
mere powder and waste of Globigerinae, but that they had a definite form
and size. I termed these bodies "coccoliths," and doubted their
organic nature. Dr. Wallich [65] verified my observation, and added the
interesting discovery, that, not unfrequently, bodies similar to these
"coccoliths" were aggregated together into spheroids, which he 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,[66] 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.
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