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All the elements have a great love of society; they cannot live alone; they have their likes and their dislikes; they contract alliances which endure for a time, but are dissolved in favor of stronger attractions.

We have mentioned the names of several natural elements. Let us see what they are, and what they have to do with man and the kingdoms of Nature. Beginning with man, let us see what becomes of him in course of time, what physical metamorphoses he undergoes, to what vile but excellent uses he is put.

That which forms the bone and muscle of a man this year may be upon his own table in the shape of potatoes or peaches one summer later. When Hamlet talked of turning the clay of Alexander into the bung of a beer-barrel, he spoke the simple truth. In that great play, Shakspeare appears to have had the transformations of material things much in his mind; for we find him alluding, in several passages, to the reciprocity which subsists between the elements of animate and inanimate things, and between the different members of the same kingdom;-as when, in conversation with the king about the dead Polonius, he makes Hamlet say, "A man may fish with the worm that hath eat of a king, and eat the fish that hath fed of the worm"; or where, over the grave of Ophelia, he traces the two ancient heroes back to their mother earth, in words some of which we have quoted.

The ancient mythology, which shadowed forth some truth in all its fables, turned these facts of Nature to its purpose. The gods of Greece, when they saw fit to remove a human being from life, sometimes reproduced him in another form of beauty, without any intermediate stages of decay. Apollo seemed to have a particular fancy for planting the boys and girls whom he had loved where he might enjoy their fragrant society. Thus, a boy named Cyparissus, who had the misfortune to kill a favorite deer, was so unwilling to be consoled, that he besought Apollo to make his mourning perpetual; and the kind god changed him

into a cypress, which is still a funereal tree. The modest virgin Daphne, who succeeded in escaping the violence of his passion, was transformed into a laurel, which is ever green and pure. And the sweet youth Hyacinthus, beloved of Apollo, being accidentally killed by a quoit which the god of day was throwing, that divinity, in his grief, caused those sweet flowers which bear his name to spring from his blood, where it fell upon the ground. It is only in the annihilation of the intervals of time between different forms of existence that these old metamorphoses, which Ovid relates, are fabulous. If our readers will bear us company a few steps, through ways which shall have diversions enough to forbid weariness, we will endeavor to satisfy them that these apparent fables are very near to every-day truths. We must begin with some plain statements.

The air which we expel from the lungs at every breath has a large proportion of carbonic acid. Let a man be shut up in an air-tight room for a day, and he will have changed nearly all the oxygen in it into this carbonic acid, and rendered it unfit for animal life. Dogs, cats, and birds would die in it. But, poisonous

as it is to man and other animals, it is a feast to plants. They want it all day and every day; not in the night,- at that time they have a taste for oxygen. This effete air, which men and animals exhale, so charged with carbonic acid, the plants drink in through every pore. They take it from the mouth of man, appropriate it to their daily uses, and in time render it back to him mingled with other ingredients in wholesome fruit. Carbonic acid is death when it combines with the blood,-as it does when we inhale it; but not so when it enters the stomach in small quantities. One inspiration of it is enough to make us dizzy,as when we enter an old well or stoop over a charcoal fire; but a draught of water fully charged with it is exhilarating and refreshing, as we know by repeated experiences at marble fountains that meet us on so many city-corners.

If plants had souls, they would be pure ones, since they can bear such contamination and not be harmed,-nay, since even from such foul food as we give them they can evolve results so beautiful. We give them our cast-off and worn-out materials, and they return us the most beautiful flowers and the most luscious fruits.

Beside carbonic acid, there are two other principal materials, which are every day passing off in an effete state, though capable of being transferred to the uses of plants. But when an animal dies, the whole substance is then at Nature's disposal. We must set aside a great deal of it for the ants and flies, who will help themselves in spite of us. If any one has never seen a carcass rapidly disappearing under the steady operations of the larva of the flesh-fly, he has yet to learn why some flies were made. The ants, too, carry it off in loads larger, if not heavier, than themselves. But carcasses of animals may go to decay, undisturbed by the ravages of these useful insects. That is, the limited partnership of Oxygen, Hydrogen, & Co., under which they agreed to carry on the operations of sheep, fox, or fish, having terminated by the death of the animal, the partners make immediate use of their liberty and go off in inorganic form in search of new engagements, leaving sulphur, phosphorus, and the other subordinate elements of the animal, to shift for themselves. They were in the employ of a sheep; they will now carry on a man or an oak-tree, a colony of insects, or something else. Under the form of carbonate of ammonia, the four elements diffuse themselves through the air, or are absorbed by the earth, and offer themselves at once to the roots and leaves of the trees, as ready to go on with their vivifying operations as they were in behalf of the animals. There are some plants which seem not to be left to the chances of securing their nourishment from the carbonate of ammonia that the air and the soil contain, but are contrived so as to entrap living animals and hold them fast while they undergo decomposition,

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so that all their gases may be absorbed by them alone. Thus, "the little Sundew exudes a gluey secretion from the surface of its leaves, which serves to attract and retain insects, the decay of whose bodies seems to contribute to its existence." And the Dionæa, or Venus's Fly-trap of the Southern States, has some leaves which fold together upon any insect that alights upon their upper surface; and by means of a row of long spines that fringes the leaves, they prevent his escape. The more active the struggles of the captive, the closer grows the hold of the leaf, and speedily destroys him. The plant appears to derive nutriment from the decomposition of its victims. "Plants of this kind, which have been kept in hot-houses in England, from which insects were carefully excluded, have been observed to languish, but were restored by placing little bits of meat upon their traps, the decay of these seeming to answer the same purpose."

The four elements already referred to are by no means all the material ingredients of animal bodies. There are, also, phosphorus, lime, magnesia, soda, sulphur, chlorine, and iron; and if you believe some chemists, there is hardly a mineral in common use that may not be found in the human body. We doubt, however, whether lead, arsenic, and silver are there, without the intervention of the doctor.

What becomes of the phosphorus and the rest, when an animal dies? Oh, they take up new business, too. They are as indispensable to the animal frame as the four most prominent ingredients. We eat a great deal of bread and meat, and a little salt, but the little salt is as important to continued life as the large bread. There is hardly a tissue in the body from which phosphorus, in combination with lime, is absent; so that the composition of lucifer-matches is by no means the most important use of this element. The luminous appearance which some putrefying substances, particularly fish, present at night, is due to the slow combustion of phosphorus which takes

place as this element escapes into the air from the decomposing tissues.

The necessity for the steady supply of phosphorus and lime to the body is the cause of the popularity of Mapes's superphosphate of lime as a manure. The farmers who buy it, perhaps, do not know that their bones and other parts are made of it, and that this is the reason they must furnish it to their land; for between the land and the farmer's bones are two or three other factories that require the same material. All the farmer knows is, that his grass and his corn grow better for the superphosphate. But what he has not thought of we will tell you, - - that man finds his phosphate of lime in the milk and meat of the cow, and she finds her supply in the grass and corn, which look to the farmer to see that their stock of this useful mineral compound does not fall short. Thus in milk and meat and corn, which constitute so large a part of our diet, we have always our phosphate of lime. There are many other sources whence we can derive it, but these will do for the present. And thus, when an animal dies and has no further use for his phosphate of lime, it is washed into the soil around, after decomposition of the body has set it free, and goes to make new grass and corn. Bone-earth (pounded bones) is a common top-dressing for grass-lands.

A small proportion of sulphur is found in flesh and blood. We prove its presence in the egg by common experience. An egg-from which it escapes more easily than from flesh-discovers its presence by blackening silver, as every housekeeper knows, whose social position is too high for bone egg-spoons or too low for gold ones. This passion which sulphur entertains for silver is very strong, as every one knows who has ever been under that wholesome discipline which had its weekly recurrence at the delightful institution of Dotheboy's Hall; and what Anglo-Saxon ever grew up, innocent of that delectable vernal medicine to which we refer? Has he not found all the silver change in his pocket grow black, suggesting very

unpleasant suspicions of bogus coin? The sulphur, being more than is wanted in the economy of the system, has made its escape through every pore in his skin, and, of course, fraternizes with the silver on its way. But it was of the sulphur which is natural to the body and always found there that we were speaking. When the animal dies, and the vital forces give way to chemical affinities, when the phosphorus and the rest take their departure, the sulphur, too, finds itself occupation in new fields of duty.

Chlorine and sodium, two more of the elements of animal structures, produce, in combination, common salt, without which our food would be so insipid, that we have the best evidence of its being a necessary article of diet. The body has many uses for salt. It is found in the tears, as we are informed by poets, who talk of “briny drops” and “saut, saut tears"; though why there, unless to keep the lachrymal fluid from spoiling, in those persons who bottle up their tears for a long time, we cannot divine.

Perhaps we had better take the rest into consideration together, the magnesia and iron, and whatever other elements are found in the body. Though some of them are there in minute quantities, the structure cannot exist without them, and for their constant and sufficient supply our food must provide.

To see what becomes of all these materials after we have done with them, we must extend our inquiries among the articles of ordinary diet and ascertain from what sources we derive the several elements.

It has been sometimes believed that none but animal food contains all the elements required for the support of life. Thanks to Liebig, we have discovered that vegetable substances also, fruits, grains, and roots, contain them all, and, in most cases, in very nearly the same proportions as they are found in animals. We are not lecturing on dietetics; therefore we will not pause to explain why, although either bread or meat alone contains the various materials for flesh and

bone, it is better to combine them than to endeavor to subsist on one only.

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Whither, then, go these elements when man has done with them? The answer is,— All Nature wants them. Every plant is ready to drink them up, as soon as they have taken forms which bring them within its reach. As gases, they are inhaled by the leaves, or, dissolved in water, they are drunk up by the roots. plants have not the same appetites, and therefore they can make an amicable division of the supply. Grasses and grains want a large proportion of phosphate of lime, which they convert into husks. Peas and beans have little use for nitrogen, and resign it to others. Cabbages, cauliflowers, turnips, and celery appropriate a large share of the sulphur.

The food of plants and that of animals have this great difference: plants take their nourishment in inorganic form only; animals require to have their food in or ganic form. That is, all the various minerals, singly or combined, which compose the tissues of plants and animals,—carbon, hydrogen, phosphorus, and the rest, which we have already named,—are taken up by plants in mineral form alone. The food of animals, on the other hand, consists always of organized forms. There is no artificial process by which oxygen, carbon, and hydrogen can be brought into a form suitable for the nourishment of animals. As oxygen, carbon, and hydrogen, they are not food, will not sustain our life, and human art cannot imitate their nutritious combinations. tificial fibrine and gluten (organic principles) transcend our power of contrivance as far as the philosopher's stone cluded the grasp of the alchemists. We know exactly how many equivalents of oxygen, hydrogen, carbon, and nitrogen enter into the composition of each of the animal elements; but we can no more imitate an organic element than we can form a leaf. What we cannot do the vegetable world does for us. Thus we see why it was necessary that the earth should be clothed with vegetation before animals could be introduced. A field

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Plants, as well as animals, have their peculiar tastes. Cut off the supply of phosphate of lime from a field of corn, and it will not grow. You can easily do this by planting the same land with corn for three or four successive years, and your crop will dwindle away to nothing, unless you supply the ground every year with as much of the mineral as the corn takes away from it. All plants have the power of selecting from the soil the materials necessary to their growth; and if they do not find them in the soil, they will not grow. It is now a familiar fact, that, when an old forest of deciduous trees has been felled, evergreens will spring up in their places. The old oaks, hickories, and beeches, as any observer would discover, pass their last years in repose, simply putting out their leaves and bearing a little fruit every year, but making hardly any new wood. An oak may attain to nearly its full size, in spread of branches, in its first two hundred years, and live for five or six hundred years longer in a state of comparative rest. It seems to grow no more, simply because it has exhausted too much of the material for its nourishment from the ground around its roots. At least, we know, that, when we have cut it down, not oaks, but pines, will germinate in the same soil,-pines, which, having other necessities and taking somewhat different food, find a supply in the ground, untouched by their predecessor. Hence the rotation of crops, so much talked of by agriculturists. Before the subject was so well understood, the ground was allowed to lie fallow for

a year or two, when the crops began to grow small, that it might recover from the air the elements it had lost. We now adopt the principle of rotation, and plant beans this year where last year we put

corn.

It is not merely that plants deprive themselves of their future support by exhausting the neighboring earth of the elements they require. Some of them put into the ground substances which are poisonous to themselves or other plants. Thus, beans and peas pour out from their roots a very notable amount of a certain gum which is not at all suited to their own nourishment,- so that, if we plant beans in the same spot several successive seasons, they thrive very poorly. But this gum appears to be exactly the food for corn; if, therefore, we raise crops of beans and corn alternately, they assist each other. Liebig gives the results of a series of experiments illustrating the reciprocal actions of different species of plants. Various seeds were sprouted in water, in order to observe the nature of the excretions from their roots. It was found that the water in which plants of the family of the Leguminosa (beans and peas) grew acquired a brown color, from the substance which exuded from their roots. Plants of the same species, placed in water impregnated with these excrements, were impeded in their growth, and faded prematurely; whilst, on the contrary, corn-plants grew vigorously in it, and the color of the water diminished sensibly, so that it appeared as if a certain quantity of the excrements of the Leguminosa had really been absorbed by the corn-plants." The oak, which is the great laboratory of tannin, not only lays up stores of it in its bark and leaves, but its roots discharge into the ground enough of it to tan the rootlets of all plants that venture to put down their suction-hose into the same region, and their spongioles are so effectually closed by this process, that they can no longer perform their office, and the plant that bears them dies. Plants whose roots ramify among the roots of poppies become unwilling opium-eat

ers, from the exudation of this narcotic principle into the ground, and are stunted, like the children of Gin Lane.

The Aquarium furnishes a very interesting example of the mutual dependence of the three natural kingdoms. Here, in a box holding a few gallons of water and a little atmospheric air, is a miniature world, secluded, and supplying its own wants. Its success depends on the number and character of the animals and plants being so adapted as to secure just the requisite amount of active growth to each to sustain the life of the other: that the plants should be sufficient to support, by the superfluities of their growth, the vegetarians among the animated tribes that surround them; and that all the animal tribes of the aquarium, whether subsisting upon the vegetables or on their smaller and weaker fellow-creatures, should restore to the water in excrements the mineral substances which will enable the plants to make good the daily loss occasioned by the depredations of the searovers that live upon them. Thus an aquarium, its constituents once correctly adjusted, has all the requisites for perpetuity; or rather, the only obstacle to its unlimited continuance is, that it is a mortal, and not a Divine hand, that controls its light and heat.

In the examination of the materials appropriated by plants from the soil, we find that mineral substances are sometimes taken up in solution in larger amount than the growth of the plant and the maturation of its fruit require, and the excess is deposited again in crystalline form in the substance of the plant. If we cut across a stalk of the garden rhubarb, we can see, with the aid of a microscope, the fine needle-shaped crystals of oxalate of potash lying among the fibres of the plant,- a provision for an extra supply of the oxalic acid which is the source of the intense sourness of this vegetable. When the sap of the sugarmaple is boiled down to the consistence of and allowed to stand, it sometimes deposits a considerable amount of sand; indeed, this is probably always pres

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