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 ninetyseven 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 a 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.

Now came the application of the test. Was all this obtained from the earth? It had not sensibly diminished; but, in order to make the experiment conclusive, it was again dried in an oven and put in the balance. Astonishing was the result the earth weighed only two ounces less than it did when the willow was first planted in it! yet the tree had gained one hundred and sixty-four pounds. Manifestly, then, the wood thus gained in the above-mentioned space of time was not obtained from the earth; we are therefore compelled to repeat our question, "where does the wood come from?”

The writer who narrates this experiment concludes that the wood did not come from the water, and therefore must have come from the air. As both air and water are inexhaustible in quantity, it is of no consequence, for the purposes of our reasoning, whether it came from one or both.

It is unnecessary to remark upon the several inorganic constituents, which, combining in different proportions in the various species of vegetation, exist in the soil, and must be replaced if extracted; inasmuch as the absence of any one which enters into the composition of a particular plant, is as fatal to its further growth, as the absence of all. An able chemist has familiarized the notion of the deterioration, when the crop is carried away so as to return nothing to the soil, by informing us that "for every fourteen tons of fodder taken from the soil, there are carried away two casks of potash, two casks of lime, one cask of soda, a carboy of oil of vitriol, a large demijohn of phosphoric acid, and other essential ingredients."

The soil is composed, like the plants, partly of organic and partly of inorganic constituents. The latter, or mineral portion, called the subsoil, is formed by the crumbling and decomposition of the underlying rock, or of other rocks, which have been drifted over it by the action of water, in the early convulsions of Nature, or brought down by the streams in time of freshets from the formations of their upper waters, are deposited in alluvium upon the plains of the low countries. Above the subsoil lies a deposit of mould, resulting from the decay of vegetation and of animal remains. The roots of plants, penetrating through the mould to the subsoil, extract from each the species of nutriment, organic or inorganic, of which it is composed. The object of tillage is to facilitate this process. In the order of Nature, however, and independent of tillage, it is obvious that the plant, in the decay of the leaves and branches which fall from it, and finally of its entire substance, must return to the soil all the solid matter which it had abstracted during its period of growth. If the plant was itself made the food of an animal, the same result followed at one additional remove. During the life of the animal, the soluble material of its food is returned to the earth in its urine, the insoluble in its solid excrements, and, when its life is ended, its carcass goes to repay to the earth all that remains unpaid of its borrowings. If the animal serves as food for another, or for a human being, there is but one step more in the journey to the same destination; for man, too, returns to the soil

the exact equivalent of the food which he consumes, in a state fit for immediate absorption by the roots of plants.

The underlying rocks, from which the subsoil is formed, are themselves but combinations of oxygen, with a few metallic bases. The rocks which make the crust of the earth are in the aggregate about half oxygen. It is sufficiently plain that, if by any means the constituents of the rocks are brought to the surface, and dissipate in air, or enter into the structure of plants and animals, they must return again to the earth and the atmosphere. In the Economy of Nature it is provided that the leaves of trees, which annually fall to the earth, contain from seven to fifteen times more of the earthy minerals than the trunks do. When man has exhausted the surface mould, as has been done in some of our Southern States, by sending its products to foreign lands, and abandons the fields he has impoverished, their fertility is slowly restored by means of that provision. The seeds of the pine are carried by the birds, and scattered by the winds. They sprout in the deserted soil, and, sending down a long tap-root, bring up mineral sustenance from a distance much below the reach of the plants that had sucked the upper surface dry of its nutriment. This is accumulated in the leaves, which falling and rotting upon the earth, gradually form a soil capable of bearing fruit to feed man.

If vegetation be suffered, as in the state of Nature, merely to grow and rot upon the ground, it is apparent that everything is returned to the soil that is abstracted from it. abstracted from it. It is, however, material to observe, that if the plant passes through the digestive organs of an animal, it is ground down into minute fragments, and thus prepared to unite more readily with other elements, and to fertilize the soil with more rapidity than if applied in its crude condition. It is combined, moreover, with organic elements which the animal derives from the atmosphere; and what the animal rejects is richer in nitrogen than the food in its original state. For this reason animals are kept stall-fed, in idleness, as food-producing machines.*

*"Our Norfolk farmers sometimes feed out a ton of oil-cake a day to their cattle; not to make money by the sale of the cattle, but indirectly, through the richness of the manure obtained by it. In Lancashire there was a large tract of very poor lands, which, thirty years ago, was a com

Professor Norton, at the conclusion of his " Elements of Scientific Agriculture," thus sums up the matter. "We may follow any particular substance in its course from the inanimate soil to the living plant, from the plant to the living and conscious animal, and finally see it return to the soil once more. In all its changes it remains the same in its nature, but is constantly presented to us in new forms. *** There is an endless chain of circulation from the earth up through the plant to the animal, and then again back to the parent earth. By watching this chain, and the various transformations of matter during its course, we may hope to grow constantly wiser in every department of agriculture. We discover that nothing is lost: if we burn a piece of wood it disappears, but has merely been converted into carbonic acid and water, both of which are at once ready to enter into new combinations. The animal or the plant dies, and also after a time disappears, but in its decay every particle furnishes food for a new series of living things."

It is now more than half a century since Mr. Malthus published his "Essay on Population," in which he proved - what had been shown before without creating any considerable sensation—that the human race is endowed with such a generative power as to enable it to double its numbers in twenty-five years, and that, although this rate of increase has been seldom attained, if ever, for any long period, yet the natural tendency is to increase in a geometrical ratio. He maintained, on the other hand, that, "considering the present average state of the earth, the means of subsistence, under circumstances the most favourable to human industry, could not possibly be made to increase faster than in an arithmetical ratio." He exemplifies the disparate tendencies by saying: "The human species

plete moor, in the middle of which was erected a high tower, so that the traveller might know where he was. This great moor is now reclaimed and cultivated, and pays 20 shillings (sterling) rent annually. But it is kept in this state of cultivation by this high farming. They keep cattle, feed them with oil-cake, and, though the cattle may not be worth half the oil-cake used in feeding, yet they obtain in this way a manure, which enables them to raise barley and wheat crops, sustain their families, pay their rent, and lay by something."— Prof. Johnston's Eighth Lecture before the N. Y. State Agricultural Society: Transactions of 1849, page 249.

would increase as the numbers 1, 2, 4, 8, 16, 32, 64, 128, 256; and subsistence as 1, 2, 3, 4, 5, 6, 7, 8, 9."

The elder Mill, (Elements of Political Economy, page 56,) using the term capital as including the means of subsistence, and everything else capable of being exchanged for them, states the doctrine which he held in common with Malthus, in these terms:

"It thus sufficiently appears that there is a tendency in population to increase faster than capital. If this be established, it is of no consequence to the present purpose to inquire about the rapidity of the increase. How slow soever the increase of population, provided that of capital is still slower, wages will be reduced so low, that a portion of the population will regularly die of want. Neither can this dreadful consequence be averted otherwise, than by the use of means to prevent the increase of capital from falling short of that of population."

The passage we have marked with italics, is but the necessary logical result of the free operations of the laws of human nature and physical nature, as the latter are conceived by Malthus. Humanity recoils from it, and naturally looks for a remedy in trammelling the conduct of man. Accordingly, in the succeeding pages of his book, Mr. Mill examines the question, by which course of expedients population and capital can be made to keep pace together, whether by restraining the tendency of population to increase, or by endeavouring "to accelerate beyond its natural pace the increase of capital;" and finally arrives at the conclusion that "human happiness cannot be secured by taking forcible methods to make capital increase as fast as population," and that "the grand practical problem is, to find the means of limiting the number of births."

The ideas of Mr. Malthus have been adopted, not only by Mr. Mill, but by the great body of British Economists, down to the present day, and, crossing the Channel, they have found acceptance and approval with most of the Continental writers. Various theories, it is truc, have been propounded, for the purpose of showing that the gloomy results which necessarily flow from the principles maintained by him, may be avoided, and that counteracting forces restrain the natural increase of our species. None of them, however, have recognized anything like a natural equilibrium between population and subsistence, if the former, for a long period, should expand at the rate which the native instincts of man, in their normal and