, in fact, the
remains of the creature to which the _Globigerina_ shell, or rather
skeleton, owes its existence--and which is an animal of the simplest
imaginable description. It is, in fact, a mere particle of living jelly,
without defined parts of any kind--without a mouth, nerves, muscles, or
distinct organs, and only manifesting its vitality to ordinary
observation by thrusting out and retracting from all parts of its
surface, long filamentous processes, which serve for arms and legs. Yet
this amorphous particle, devoid of everything which, in the higher
animals, we call organs, is capable of feeding, growing, and
multiplying; of separating from the ocean the small proportion of
carbonate of lime which is dissolved in sea-water; and of building up
that substance into a skeleton for itself, according to a pattern which
can be imitated by no other known agency.

The notion that animals can live and flourish in the sea, at the vast
depths from which apparently living _Globigerinae_ have been brought up,
does not agree very well with our usual conceptions respecting the
conditions of animal life; and it is not so absolutely impossible as it
might at first sight appear to be, that the _Globigerinae_ of the
Atlantic sea-bottom do not live and die where they are found.

As I have mentioned, the soundings from the great Atlantic plain are
almost entirely made up of _Globigerinae_, with the granules which have
been mentioned, and some few other calcareous shells; but a small
percentage of the chalky mud--perhaps at most some five per cent. of
it--is of a different nature, and consists of shells and skeletons
composed of silex, or pure flint. These silicious bodies belong partly
to the lowly vegetable organisms which are called _Diatomaceae_, and
partly to the minute, and extremely simple, animals, termed
_Radiolaria_. It is quite certain that these creatures do not live at
the bottom of the ocean, but at its surface--where they may be obtained
in prodigious numbers by the use of a properly constructed net. Hence
it follows that these silicious organisms, though they are not heavier
than the lightest dust, must have fallen, in some cases, through fifteen
thousand feet of water, before they reached their final resting-place on
the ocean floor. And, considering how large a surface these bodies
expose in proportion to their weight, it is probable that they occupy a
great length of time in making their burial journey from the su