The Medals of Creation, Volumes 1 and 2: First Lessons in Geology and the Study of Organic RemainsMantell, Gideon Algernon
Science
The Medals of Creation, Volumes 1 and 2: First Lessons in Geology and the Study of Organic Remains
Mantell, Gideon Algernon
Geology -- England -- Guidebooks; Paleontology
Fossil remains of the soft parts of Foraminifera. _Lign. 113._--When
examining chalk[325] and flint under the microscope with the view of
discovering the fossil bodies described by M. Ehrenberg, I observed
that the cells of the Rotaliæ in flint were frequently occupied by a
substance varying in colour from a light amber to a dark brown, and
closely resembling in appearance the body of the recent foraminifer
deprived of its shell. Under a high power, the folds of the membranous
sacs and the connecting tube were apparent, and I felt convinced that
the substance filling the cells was not inorganic, but the original
animal tissues in the state of molluskite.[326] In short, that the
animal had become immersed and preserved in the fluid silex like the
insects in amber. The appearance of the first discovered example of
this kind is represented in _Lign. 117_.
[325] In 1845.
[326] _Molluskite_: a name by which I proposed to distinguish the
carbonaceous substance resulting from the soft bodies of testaceous
mollusca.
[Illustration: Lign. 117. Rotalia in Flint, with the fossilized body of
the animal in the shell: _highly magnified_.
(_Seen by transmitted light._)]
[Sidenote: SOFT BODIES OF FORAMINIFERA.]
In a paper read before the Geological Society in 1845,[327] I
ventured to affirm the animal nature of the fossils in question; but
the supposition was regarded by geologists as very startling and
unsatisfactory; and as the specimens were enveloped in flint, the
appearance was attributed to the infiltration of mineral matter of a
different colour from the surrounding silex, into the empty chambers;
a circumstance of frequent occurrence in Ammonites, Nautili, and even
in the foraminifera; for the latter are often filled with chalk, flint,
silicate of iron, crystal, &c. as in _Lign. 116_. In these instances,
I conceive the shells were either empty when immersed in the fluid
chalk or flint, or speedily became so by the decomposition of the soft
parts of the animal. But in the fossils under consideration, I believe
the live animal was suddenly enveloped, and hermetically sealed, as
it were, in its shell, and that putrefaction was thus prevented.
The uniformity in colour, and the structure of the substance in the
cells, appeared to me incompatible with its assumed mineral origin,
and I resolved to follow up the inquiry by an examination of Rotaliæ
in chalk; in the hope that by dissolving the shell in acid (as in
recent foraminifera), the body of the animal might be detected in an
unmineralized state. After many fruitless attempts, several examples of
the soft bodies of Rotaliæ were obtained from the grey chalk of Dover,
in an extraordinary state of preservation.[328]
[327] Notes of a Microscopical Examination of the Chalk and Flint of the
South-East of England, with Remarks on the Animalculites of certain
Tertiary and Modern Deposits. Published in the Ann. Nat. Hist., Aug.
1845.
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