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WHAT DOES "SMALL" MEAN IN
NATURE?
An eminent naturalist
observes that the telescope teaches us that every world is an atom, and
the microscope that every atom is a world. The reader will remember with
what eloquence and force the same contrast is employed by Chalmers, in his
"Astronomical Discourses," to demonstrate the care and benevolence with
which the Almighty watches over the minutest organism in a drop of water,
equally with the most magnificent of the orbs that roll through the
amplitude of space. The microscope, by extending to the inquisitive eye of
science the domain of animated creation in a direction where it was not
previously imagined to have an existence, has dispelled for ever the
gloomy misgivings which took possession, even of thoughtful minds, on the
revelations of the modern astronomy, and which infidelity shaped into an
argument against a superintending and special Providence, by perverting
the devout sentiment of the Psalmist, "When I consider thy heavens, the
work of thy fingers, the moon and the stars, which thou hast ordained;
what is man, that thou art mindful of him? and the son of man, that thou
visitest him!" In this as in every department of creation, the teachings
of science are found in harmony with Divine Revelation. The works of God
reflect a clear and steady light upon His Word. The structure and
adaptations of every organised being, fossil or recent, bear testimony to
the power and the "manifold wisdom" of the Creator. The monad and the
mammoth alike witness that the tender mercy of God is over all His works.
From regions the most widely separated in space and magnitude, from time
extending through the incalculable ages of the history of creation
recorded in the rocks, the observer who addresses himself to the study of
nature with a reverent and loving spirit, derives the same elevating and
assuring lesson. He is conscious of one all-pervading and august Presence
and Power, whether he views under the field of the microscope the
multitudinous organisms inclosed in a grain of sand; or when the telescope
discloses to him new creations amongst the silent stars; or when an
annular eclipse attracts the regards and excites the admiration of an
assembled people; or when we gaze on such a majestic spectacle as that
which filled so many hearts with rapture, and so many eyes with tears,
when the memorable comet of 1858 was seen blending its mild lustre with
the radiant splendours of Arcturus. In the view of the Infinite Mind, the
least and the greatest of created things fulfil their destined purpose in
the plan of the universe; and, as necessary and indispensable parts of the
wondrous whole, the Almighty Maker watches with paternal solicitude over
all the works of His hands. The creatures made in His own image, and
endowed with indestructible faculties of thought and feeling, are His
peculiar care. Upon them He has lavished the bounties of His providence
and the riches of redeeming grace. "He healeth the broken in heart, and
bindeth up their wounds. He telleth the number of the stars: he calleth
them all by their names."
"What does small mean in
nature?" The question was suggested to the mind of a German naturalist
while investigating into the inconceivable multitudes of microscopical
organic forms entering into the constitution of the chalk formation. This
geological system extends over a vast portion of the globe; and modern
observation has proved that, probably to the amount of fully one-half, it
consists of the remains of animals which were deposited at the bottom of a
primeval ocean. Many of the remains are those of shell-fish, sea-urchins,
zoophytes, and other animals; but by much the largest proportion of the
formation is composed of the shells of minute animalculæ, only discernible
by the microscope. The mind is overwhelmed by the idea of the myriads of
animated atoms which have contributed by their remains to build up masses
of chalk, constituting mountain chains in Europe, Asia, Africa, and
America. The purer forms of common white chalk exhibit, under the
microscope, an aggregation of shells, corals, and other structures, of
which a million individuals are contained in a cubic inch of the
substance. A hundred thousand of these minute shells are computed to enter
into the constitution of the chalk employed in enamelling an ordinary
visiting card. They are chiefly the shells of a group of animals, of
extremely simple organisation, named Foraminifera. The body of the animal
consists of little else than an atom of thin transparent glair or jelly.
It begins life by constructing a shell of one chamber; but in proportion
as the size of the body exceeds that of its tiny dwelling, it adds one
chamber after another, corresponding to its growing dimensions, till it
finally settles in its mature state in the outermost and roomiest cavity
of the series. The shell then bears some resemblance to that of the
ancient ammonite and modern nautilus. With these animals the foraminifera
were long confounded; but the latter belong to the lowest forms of animal
life, being closely allied to the infusoria, animalculæ abounding in water
containing vegetable infusions; whereas the ammonite and nautilus
represent the mollusca, or shell-fish of highest organisation. The
nummulite characterising immense beds of calcareous rock in the Alps and
Pyrenees, and also the limestone constituting the foundation of the Great
Pyramid of Egypt, and forming the principal mass of the huge body of the
Sphinx, is one of the largest species of the order. It derives its name
from its similarity to a coin ; and the legend has lingered in Egypt since
the time of Strabo, that the nummulites of the pyramids, familiar to all
travellers in that country, are the lentils upon which the builders fed
while rearing those imperishable edifices, and which, in the progress of
time, have been converted into stone. But in general the shells of the
foraminifera are of excessive minuteness. The rocks upon which the city of
Paris rests are composed almost wholly of these shells, which are packed
together as closely as the grains in a heap of turnip-seed; and the houses
of the capital are built of the same curious organism. Existing
sea-bottoms appear to be covered to unknown depths by recent species of
foraminifera. When the officers of the ship Dolphin were sounding the bed
of the Atlantic for the electric telegraph, the matter brought up by the
lead from a depth of two thousand fathoms in mid-ocean was found to be
composed entirely of the shells of these animalculæ, without any admixture
of unorganised or merely earthy substances. It was, therefore, reasonably
expected that the submerged wire would be coated over with a deposit of
the shells of the foraminifera, and thus become permanently protected
against danger from friction by oceanic currents within the space of three
years. An ounce of sand obtained from the Caribbean Sea was estimated to
contain the amazing number of 3,840,000 shells. The German investigation
of the organisms of the chalk took an illustration from the blasting of
the cliff at Dover for the railway, in 1843. Years of labour were expended
in preparing shafts and galleries, and the largest charge of gunpowder
ever employed was fired by a powerful galvanic battery. A million of tons
of the chalk rock were torn away in a minute, almost silently, and a
surface of nearly fifteen acres was covered twenty feet deep with its
fragments. "And with what," says the writer, "did the power of the human
mind enter into this giant struggle ? With the remains of creatures, a
thousand of which might be annihilated by the pressure of a finger! We
wonder, and ask ourselves, What does small mean in nature ? "
The Bergmehl, or mountain-meal of the north of Europe, used in Sweden and
other countries as an article of food, was found by Ehrenberg to consist
of the shells of minute animals, which had been deposited in water at a
remote period, but the exuviæ of which still retained sufficient animal
matter to render them nutritive when mixed with flour. Till this discovery
was made by the most ingenious of microscopists, the mountain-meal was
considered to afford an exception to the universal fact, that the mineral
kingdom is incapable, directly, of yielding food for animals.
Another vast group of minute organisms inhabit the debateable region
between the animal and the vegetable kingdom. Zoologists and botanists
long did battle for possession of this border territory, which, being
often taken and retaken, may, at length, be considered to be finally
established as a province of the kingdom of plants, the inhabitants being
distinguished by the name of the Diatomace. It was only on the cessation
of hostilities, however, that their nature, habits, and diversified forms
became the subject of systematic study; and, of late years, the microscope
has revealed the fact of their existing in earth, water, and air, and even
in the tissues of animals and plants, in bewildering profusion. The diatom
(or brittle-wort) is a plant consisting of a single cell, yet it
represents the fundamental principle of the most complex vegetable
structures, and illustrates the uniformity of the plan of organisation in
the vegetable kingdom; for the sturdy oak, the patrician palm, and the
peerless Wellingtonia of the Californian forest is each an aggregation of
cells. Unlike the delicate calcareous shells of the animals previously
described, the coverings of these unicellular plants are siliceous and
indestructible. It is, indeed, only after their separation from the
substances containing them, by exposure to the action of the strongest
heat and the fiercest chemical acids, that they are produced in all their
crystalline brilliancy and purity, and are fit for being mounted on shells
as microscopic objects. The cell multiplies by spontaneous fission or
sub-division, a process which proceeds in a geometrical ratio, and often
with great rapidity. The progeny of a single individual, on the moderate
calculation that each successive act of self-division takes place every
twenty-four hours, would amount in a month to one thousand millions! Some
species inhabit the sea, others are found only in fresh water. The
favourite habitats of many species are the stones of mountain streams and
water-falls. Shallow pools, the mouths of rivers, roadside ditches,
water-troughs, and cisterns, abound with various species. Ehrenberg (who
persists in classifying the diatoms with infusorial animalculæ) has found
them alike in the oldest and the newest fossiliferous rocks. Darwin
witnessed them drifting in clouds from the continent of America to that of
Africa, and coming in contact with the sails of the ship in which he was a
voyager. Dr Hooker discovered them in myriads in the ice within the
Antarctic circle; and the same observer, on examining the mud brought up
by the lead on sounding a bank on the flanks of Victoria Land, not less
than 400 miles long, and 120 broad, and of a depth which could not be
conjectured, ascertained that it was almost entirely composed of the
siliceous remains of diatoms. No description can convey an adequate idea
of the symmetry and beauty displayed in the forms of these crystalline
atoms. The infinitesimally minute striations and sculptures on the surface
of many species, task the highest powers of the optician's glass. Like the
higher tribes of plants, the diatoms give off oxygen gas, under the
influence of the sun's light and heat; the result, doubtless, of the
decomposition of carbonic acid gas, which all vegetables abstract from the
air. They are thu3 rendered instrumental in maintaining the atmosphere in
a state of purity and salubrity for the respiration of animals. A still
more important function is performed by the lower tribes both of animals
and plants. Occupying a position on the very verge of organised being,
they are employed to prevent the tendency of decomposing animal and
vegetable matter to pass into the gaseous state, and return to the
inorganic world. "These wakeful members of Nature's invisible police," to
use the words of Professor Owen, "are everywhere ready to arrest the
fugitive organised particles, and turn them back into the ascending stream
of life." |
