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"The fundamental property of vitality, common to all organized bodies, consists in their constant material renovation; an attribute which distinguishes them from the inert or unorganized bodies, whose composition is always fixed. The latter may be artificially constructed by putting together their constituent parts; while no chemical skill is adequate to the production of wood, sugar, starch, fat, gelatine, flesh, &c., whose elements, though equally simple and equally well known, refuse to combine in organized compounds, otherwise than under the operations of that mysterious power which we call vital force. The growth of a crystal-the highest inorganic process we are acquainted with, involving but one action, that of accretion-may be conducted artificially by the chemist; while the growth of a simple cell, such as compose the yeast fungus, and the minute alge which color the waters of stagnant pools, though the lowest organic process, involves the double action of accretion and disintegration, and defies the power of science to produce. The meanest and least complex form of life it is beyond man's reach to fashion.

"While the ultimate elements of vitality are profusely furnished in the natural world, vegetables alone have sufficient assimilative power to compose their tissues directly from inorganic matter, the liquid and gaseous materials, and the earthy particles, which are minerals decomposed. Not only so, but no part of an organized being can serve as food to vegetables, until, by the process of putrefaction and decay, it has assumed the form of inorganic matter. It is this capacity which renders vegetable organization the essential base of all other. In the absence of vegetation all animals must be carnivorous, and subsist by mutual destruction, which would soon exterminate their species. For this reason it must necessarily precede animal life. That such has been the fact is abundantly proved by geological research, which, reading the history of buried ages in the rocks, shows us that a period of long duration intervened, after the growth of lichens and ferns in the primitive world, before the lowest order of animals made its appearance on the earth.

"Animal organism, on the contrary, requires for its support and development highly organized atoms. The food of animals, in all circumstances, consists of parts of organisms. While some of them feed directly upon vegetation, others, requiring that matter should

have taken on a higher order of life before it can support their own, prey upon other and inferior animals. Having a lower assimilative capacity, it is necessary that their food should have been brought by intermediate agents, into combinations agreeing more nearly with those of their own tissues than even vegetable organization. Without some arrangement and gradation of this character, the higher natures must either perish for lack of food, or consume all their activity in chemical transformations, without reserving any for locomotion or other muscular effort. We may remark here, that with this necessity of overcoming and capturing prey, arises a degree of mental power, enabling the carnivorous animals to devise plans, and to compass by association with their fellows, ends beyond their unassisted power. The spider spins an artful web to catch flies, and wolves hunt their game in packs. The superior functions are everywhere united with less energy in the inferior. Those beings in whom the latter prevail are self-sufficing and independent, but have little reach and power beyond the satisfaction of the low primary wants. As we rise in the scale up to man, the crown and roof of things, we find him, of all, the most dependent, the most prone to association, for which, by the faculty of speech, he is most adapted; and by means of association, though alone the least self-sufficing of all beings, he wins the dominion over nature and her forces, whether animate or inanimate.

"Another distinction between animal and vegetable life is this: The growth and development of vegetables depend upon the elimination of oxygen from the other component parts of their nourishment. They are perpetually exhaling this gas from the surfaces of their leaves into the air. The life of animals exhibits itself in the continual absorption of the oxygen of the air, and its combination with certain component parts of the body. Its office is to generate animal heat by burning the combustible substances of the frame. It combines with the carbon of the food, and in so doing precisely the same quantity of heat is disengaged as if it had been directly burned in the air. The result is carbonic acid gas, which is thrown out of the lungs and the skin; this is absorbed by the leaves of plants, the carbon separated and incorporated into their substance, and the oxygen again exhaled into the atmosphere, to resume its round of circulation.

"To trace the cycle a little further the carbon uniting with

Man eats

When it

water in the plant, forms, among other things, starch, which the sap conveys to the part requiring it. It is found largely in the seeds. Starch exists in wheat to the extent of one-half the weight of the grain, and it consists of carbon and water only. the wheat, but we find no starch in the human body. enters our frames it undergoes a chemical change, a slow burning, in fact, in which the carbon of the starch combines with oxygen, forming carbonic acid gas, which, together with the liberated water in the shape of vapor, is thrown out of the human system into the atmosphere, to be again converted in the laboratory of the plant into the starch from which they were derived. Having served our purpose in keeping up the internal warmth upon which animal life depends, the disengaged elements are recomposed by the plants into part of their substance, which when completed again serve as fuel in the animal economy.

"The instances we have given, will, so far as relates to their organic constituents, suffice to exemplify the law that animals and vegetables are mutually convertible one into the other, and depend on each other for existence. The interchange of their elements is accomplished through the medium of the atmosphere from which plants derive far the greatest portion of their nutriment. It is found by burning any form of vegetable matter, in a dry state, that the organic part, which is combustible and disappears in the air, is by far the largest. It ordinarily constitutes from ninety to ninety-seven pounds in every hundred. This part of the plant can only have been formed from air at first, if not directly, yet from compounds whose elements were themselves derived from air, existing in the soil, and taken up by the roots. In the language of Professor Draper, in his Chemistry of Plants, Atmospheric air is the grand receptacle from which all things spring and to which they all return. It is the cradle of vegetable, and the coffin of animal life.'

"About one pound in ten, upon an average, of the dry weight of cultivated plants, including their roots, stems, leaves and seeds, is formed of matter which existed as a part of the solid substance of the soil in which the plant grew. Every organ in the stalk, stems, and leaves of the plant has a reticulated framework of inorganic matter, the base of which is either silex or lime. Silex, familiar to us in the various shapes of white sand, flint, and crystal

of quartz, constitutes more than sixty per cent. in quantity of the soil, sometimes forming as much as ninety-five per cent.* It gives porosity to the soil, in order that water and air may be admitted into its texture. Alumina, the base of clay, on the contrary, renders it compact and retentive. The office of silex in plants is to give strength to the straw of wheat for example; it serves as the bone of all the grass family. From ninety-three to one hundred and fifty pounds of soluble flint are required to form an acre of wheat."+

§ 2. Development thus beginning in the stomach of vegetables is continued in that of animals, until the earth is, by degrees, prepared to serve the purpose of man-and with his coming we find the important difference that whereas all other animals were bound to continue forever the slaves of nature, he alone was gifted with the faculties required for enabling him to become her master, and to make her do his work.

Casting our eyes at the present moment over the earth, we see the same forces everywhere in action, producing new combinations for the support of vegetable life, as a preparation of land as a residence at first of the lower animals, but ultimately for that of man. The amount of heat by which the sea water is raised in the form of vapor is estimated as being equal to the power of 16 billions of horses. Condensed again, that vapor reassumes the form of water,

* "Two hundred pounds weight of earth was dried in an oven, and afterwards put into an earthen vessel. The earth was then moistened with rain water, and a willow-tree, weighing five pounds, was placed therein. During the space of five years the earth was carefully watered with rain water, or pure water; the willow grew and flourished, and to prevent the earth being mixed with fresh earth or dust blown to it by the winds, it was covered with a metal plate perforated with a great number of small holes suitable for the free admission of air only. After growing in the air for five years, the tree was removed and found to weigh 169 pounds and about three ounces; the leaves which fell from the tree every autumn not being included in this weight. The earth was then removed from the vessel, again dried in the oven and afterwards weighed when it was discovered to have lost only about two ounces of its original weight: thus 164 pounds of woody fibre, bark and roots, were certainly produced, but from what source? The air has been discovered to be the source of solid element at last. This statement may at first appear incredible, but on slight reflection its truth is proved, because the atmosphere contains carbonic acid, which is the compound of 714 parts by weight, of oxygen, and 338 parts by weight, of carbon."

† Smith. Manual of Political Economy, p. 25.

which descending in rain, has again to seek the ocean, and in its passage carries with it large quantities of soil, resulting from the decomposition of the rocks of which the earth is formed— and that decomposition is in its turn a consequence of the evervarying temperatures, themselves consequences of motion among the particles of which the water and the air are composed. "The frost," says Dr. Clarke, "is God's plow which he drives through every inch of the ground, opening each clod, and pulverizing the whole," and fitting all the parts for readily entering into new combinations.

The particles of earth thus yielded are, by means of the moving waters, brought into close connection with each other, and here again we find difference leading to combination and producing motion. The greater the variety of the particles, the greater will be the ability of the compound to yield support to vegetable life, as is seen to be the case in the deltas of the Mississippi, the Amazon, and the Ganges, all furnishing trees of gigantic size, surrounded by shrubs of every description, growing in the rankest luxuriance. Here we find the lower forms of animal life, but the impurity of the air forbids that they should, during a long period of time, become the residence of man, or even of the higher order of brute animals.

Vast quantities of this earth pass into the ocean, and here it is taken up and passed through the stomach of myriads of animated beings, of which the ocean is the residence. The recent deep sea soundings of the Atlantic have brought to light the fact that no earth is found to attach itself to the lead, while hosts of microscopic animals are brought by it from the bottom of the great deep.

"Within its bosom," says a recent writer, "tiny insects are at work, upon which nature has imposed, in addition to the quest for food and the care for their offspring, the perpetual labor of building new houses. For defence as well as for shelter, the shell-fish toils continually, repairing, enlarging, and renewing his own dwellingplace; and dying at last, he leaves it as a contribution to the growing thickness of shelly limestone. For thousands of miles, in more southern seas, still humbler insects erect their massive coral walls, which, 'now skirting long coastlines, and now encircling solitary islands, bid defiance to the angriest waters; and, as they die, generation after generation, they leave, in rocky beds of coral

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