Sir James Ross was himself a naturalist of no mean acquirements, and Dr.
Hooker,[3] the present President of the Royal Society, accompanied him as
naturalist to the expedition, so that the observations upon the fauna and
flora of the Antarctic regions made during this cruise were sure to have
a peculiar value and importance, even had not the attention of the
voyagers been particularly directed to the importance of noting the
occurrence of the minutest forms of animal and vegetable life in the
ocean.

[Footnote 3: Now Sir Joseph Hooker. 1894.]

Among the scientific instructions for the voyage drawn up by a committee
of the Royal Society, however, there is a remarkable letter from Von
Humboldt to Lord Minto, then First Lord of the Admiralty, in which, among
other things, he dwells upon the significance of the researches into the
microscopic composition of rocks, and the discovery of the great share
which microscopic organisms take in the formation of the crust of the
earth at the present day, made by Ehrenberg in the years 1836-39.
Ehrenberg, in fact, had shown that the extensive beds of "rotten-stone"
or "Tripoli" which occur in various parts of the world, and notably at
Bilin in Bohemia, consisted of accumulations of the silicious cases and
skeletons of _Diatomaceoe_, sponges, and _Radiolaria_; he had proved that
similar deposits were being formed by _Diatomaceoe_, in the pools of the
Thiergarten in Berlin and elsewhere, and had pointed out that, if it were
commercially worth while, rotten-stone might be manufactured by a process
of diatom-culture. Observations conducted at Cuxhaven in 1839, had
revealed the existence, at the surface of the waters of the Baltic, of
living Diatoms and _Radiolaria_ of the same species as those which, in a
fossil state, constitute extensive rocks of tertiary age at Caltanisetta,
Zante, and Oran, on the shores of the Mediterranean.