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Good Words 1860
Sketches in Natural History


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 Diatomaceœ. 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."

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