organisms. Whether the same generalization may be extended to aluminous
rocks, depends upon the conclusion to be drawn from the facts respecting
the red clay areas brought to light by the _Challenger_. If we accept the
view taken by Wyville Thomson and his colleagues--that the red clay is
the residuum left after the calcareous matter of the _Globigerinoe_ ooze
has been dissolved away--then clay is as much a product of life as
limestone, and all known derivatives of clay may have formed part of
animal bodies.

[Footnote 9: "Petrificata montium calcariorum non filii sed parentes
sunt, cum omnis calx oriatur ab animalibus."--_Systema Naturae_, Ed. xii.,
t. iii., p. 154. It must be recollected that Linnaeus included silex, as
well as limestone, under the name of "calx," and that he would probably
have arranged Diatoms among animals, as part of "chaos." Ehrenberg quotes
another even more pithy passage, which I have not been able to find in
any edition of the _Systema_ accessible to me: "Sic lapides ab
animalibus, nec vice versa. Sic runes saxei non primaevi, sed temporis
filiae."]

So long as the _Globigerinoe_;, actually collected at the surface, have
not been demonstrated to contain the elements of clay, the _Challenger_
hypothesis, as I may term it, must be accepted with reserve and
provisionally, but, at present, I cannot but think that it is more
probable than any other suggestion which has been made.

Accepting it provisionally, we arrive at the remarkable result that all
the chief known constituents of the crust of the earth may have formed
part of living bodies; that they may be the "ash" of protoplasm; that the
"_rupes saxei_" are not only _"temporis,"_ but "_vitae filiae_"; and,
consequently, that the time during which life has been active on the