Much of this curious information was unknown, or at least only
suspected, when Ehrenberg began his microscopical investigations. From
small samples of chalk reduced to powder, placed upon the object-glass,
and examined under the microscope, Ehrenberg prepared the designs which
we reproduce from his learned micrographical work, in which some of the
elegant forms discovered in the Chalk are illustrated, greatly
magnified. Fig. 126 represents the chalk of Meudon, in France, in which
ammonite-like forms of Foraminifera and others, equally beautiful,
appear. Fig. 127, from the chalk of Gravesend, contains similar objects.
Fig. 128 is an example of chalk from the island of Moën, in Denmark;
and Fig. 129, that which is found in the Tertiary rocks of Cattolica, in
Sicily. In all these the shells of Ammonites appear, with clusters of
round Foraminifera and other Zoophytes. In two of these engravings
(Figs. 126 and 128), the chalk is represented in two modes--in the upper
half, by transparency or transmitted light; in the lower half, the mass
is exhibited by superficial or reflected light.
[Illustration: Chalk under the Microscope.