I am not
raising a merely fanciful and unreal objection. Very learned men, in
former days, have even entertained the notion that all the formed
things found in rocks are of this nature; and if no such conception is
at present held to be admissible, it is because long and varied
experience has now shown that mineral matter never does assume the
form and structure we find in fossils. If anyone were to try to
persuade you that an oyster-shell (which is also chiefly composed of
carbonate of lime) had crystallized out of sea-water, I suppose you
would laugh at the absurdity. Your laughter would be justified by the
fact that all experience tends to show that oyster-shells are formed
by the agency of oysters, and in no other way. And if there were no
better reasons, we should be justified, on like grounds, in believing
that Globigerina is not the product of anything but vital activity.
Happily, however, better evidence in proof of the organic nature of
the Globigerinae than that of analogy is forthcoming. It so happens
that calcareous skeletons, exactly similar to the Globigerinae of the
chalk, are being formed, at the present moment, by minute living
creatures, which flourish in multitudes, literally more numerous than
the sands of the sea-shore, over a large extent of that part of the
earth's surface which is covered by the ocean.
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