Discourses: Biological and Geological Essays | Page 7

nature of
the Globigerinoe of the chalk,--it is unnecessary to speak of them.
Globigerinoe of every size, from the smallest to the largest, are
associated together in the Atlantic mud, and the chambers of many are
filled by a soft animal matter. This soft substance is, in fact, the
remains of the creature to which the Globigerinoe 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 Globigerinoe; 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 Globigcrinoe 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 Globigerinoe, 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 Diatomaceoe, 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 surface of the Atlantic to the
bottom.
But if the Radiolaria and Diatoms are thus rained upon the bottom of
the sea, from the superficial layer of its waters in which they pass their
lives, it is obviously possible that the Globigerinoe may be similarly
derived; and if they were so, it would be much more easy to understand
how they obtain their supply of food than it is at present. Nevertheless,
the positive and negative evidence all points the other way. The
skeletons of the full-grown, deep-sea Globigerinoe are so remarkably
solid and heavy in proportion to their surface as to seem little fitted for
floating; and, as a matter of fact, they are not to be found along with the
Diatoms and Radiolaria in the uppermost stratum of the open ocean. It
has been observed, again, that the abundance of Globigerinoe, in
proportion to other organisms, of like kind, increases with the depth of
the sea; and that deep-water Globigerinoe are larger than those which

live in shallower parts of the sea; and such facts negative the
supposition that these organisms have been swept by currents from the
shallows into the deeps of the Atlantic. It therefore seems to be hardly
doubtful that these wonderful creatures live and die at the depths in
which they are found.[2]
[Footnote 2: During the cruise of H.M.S. Bulldog, commanded by Sir
Leopold M'Clintock, in 1860, living star-fish were brought up, clinging
to the lowest part of the sounding-line, from a depth of 1,260 fathoms,
midway between Cape Farewell, in Greenland, and the Rockall banks.
Dr. Wallich ascertained that the sea-bottom at this point consisted of
the ordinary Globigerina ooze, and that the stomachs of the star-fishes
were full of Globigerinoe. This discovery removes all objections to the
existence of living Globigerinoe at great depths, which are based upon
the supposed difficulty of maintaining animal life under such
conditions; and it throws the burden of proof upon those who object to
the supposition that the Globigerinoe live and die where they are
found.]
However, the important points for us are, that the