The Circulation of Matter in Nature

THE CIRCULATION OF MATTER IN NATURE. BY DR. JOHN A. WIDTSOE, DIRECTOR EXPERIMENT STATION, STATE AGRICULTURAL COLLEGE, LOGAN, UTAH.

The economy displayed in the operations of nature is one of the first great laws that impresses itself upon the mind of the student. Any apparent lavishness that may at times be observed, if studied in connection with the general welfare of the world, will be bound to be part of nature's law of economy. One of the chief devices by which nature is enabled to prevent waste, is tha repeated use, for different purposes, of one and the same sub- stance. This leads to the fact that at any moment, we find our- selves surrounded by the same material in various guises, each of which appears to be entirely distinct from the others. This leads to a circulation of matter; a substance begins its journey in some definite form, and, after numerous changes, comes back to its ini- tial condition. It is this phase of nature's economy that this paper intends to discuss. Water shows perhaps most direct manner the law of in the the circulation of matter. The ocean, which is the great reser- voir of water, may be taken as the starting point. The energy of the sun's rays as they strike upon the waves, is sufficient to change a small portion of water into vapor. This vapor rises in the air until the lower temperature of the upper aerial regions condenses it into droplets of water, which, when great numbers are near together, we call clouds. The winds drive the clouds in one way and in another, over the ocean, over continents, over valleys and

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over mountains. When it happens that the relatively warm cloud- masses are driven against the cold mountain peaks, the droplets of cloud-water unite into larger drops, and fall as rain. From then on, the water taken from the ocean enters into many of the operations of nature. The rain may fall upon the hillside and flow down, at once, into a river. The river may flow without hindrance from the high- lands into the ocean, and thus return in a very short time the water to the ocean whence it was taken. This, however, would be the exception. Usually the history of the rain between the time it reaches the earth, and enters the ocean, is long and involved.

The rain may fall just before a frost, and may be kept in the crack of a rock as ice throughout the winter. There, by its freez- ing and melting, it will tend to break up the rock and to make soil of it. Or, it may fall upon an iron ore, and be taken into the structure of the mineral, there to be kept until the iron is ex- tracted in the hot furnaces of man. Or, the rain may reach the river in safety, but a thirsty animal may lap it before its journey is far done. Then it will pass into the blood of that animal to be used perhaps for days, perhaps for months. Or, it may fall upon a field of growing grain, and, as it sinks downward, the soil parti- cles will hold it, and a tiny rootlet will take it into the plant, and there it will be pumped up into the stems and leaves and flowers of the plant. It may remain in that plant for many days; may remain there until the crop is harvested, and the grain made into flour and bread. Then it may be eaten by man, and taken into his system to serve the human body. Even when it escapes from these different prisons, it may not be helped on in its search for the ocean, for, it may be evaporated from the skin of the man or the leaves of the plant, as vapor, and may remain for months in the air before it is precipitated again as rain. Even then it is not better off than before, for there is no certainty when it will escape the rock, the mineral, the plant or the animal. Therefore, it may be that particles of water now found in the atmosphere left the ocean hundreds of years ago, and are still seeking to return to the parent body. However, the rule is that the greater part of the water in the air returns to the ocean in a comparatively short time after its vaporization; and that only a very small portion is com-

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pelled to remain away, indefinitely. In a rapid, restless manner, water passes through the phases of its existence: ocean water, vapor, clouds, snow or rain, part of plant or animal, river water, ocean water again. Think of the story that a glassfull of water might tell! In a dim, long-past geological age, it helped to form, perhaps, the thick blood of a sluggish reptilian monster; ages later it was drawn up through the slender trunk of a palm, to make the sweet milk of a <jocoa-nut; after another cycle of changes, it was sipped, perhaps, by a Socrates or a Plato, while rich thoughts were forming within his brain; an^ it is not impossible that centuries later, Napoleon, weary with battle, drank the same water, as darkness fell upon Waterloo. Who knows? Certain it is, that the water of the earth, during the ages of the earth's life, has been passing actively from place to place; and that, when man came, the water had labored long to make the earth a fit place for him. The circulation of the element carbon is not inferior in its importance to man, to that of water. Carbon is known in its ele- mentary condition in three distinct forms, viz., diamond, charcoal and graphite, (the material commonly known as blacklead, and used in lead-pencils.) Though these substances are very different in their physical properties, in their chemical reactions they are precisely the same. Chemists have already suceeded in imitating nature in so far that small, but perfect diamonds may be made from charcoal. When diamonds, charcoal and graphite are sub- jected to the proper degree of heat, in the presence of the element oxygen, the carbon and the oxygen unite to form the gas carbon dioxide. In other words, carbon burns with the formation of carbon dioxide. Since burning has been going on since the crea- tion of the earth, the atmosphere contains, now, a very large quantity of carbon dioxide. It is believed that in early geological

days, the atmosphere contained even more of this gas than it does now. We do not know in what form carbon was present at the creation of the earth, but it is probable that, from the very beginning, the atmosphere has contained a large quantity of car- bon dioxide. Beginning with the carbon dioxide of the air, we trace some of the changes that carbon undergoes in its circulation. First, as

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it moves about with every disturbance of the atmosphere, it may be driven over the leaves of trees, shrubs, weeds or cultivated plants. The ever- watchful cells of the leaves seize upon the mole- cules of carbon dioxide; and, once within the leaf, they are broken up into carbon and oxygen. The carbon, thus taken from the air, may be used by the plant in various ways. It may be united with

the water of the plant to form sugar, starch, woody fibre, or fat; or, it may unite with water and the element nitrogen to form the fleshforming portion of plants. In any case, it is stored away in the root, stem, leaves or seeds of the plant, to be kept there until the plant dies. If the carbon is taken up by a young oak, it may be imprisoned in the trunk hundreds of years; if by a rapidly

^growing weed, it may be partly freed after a few weeks. When the dead parts of the plants fall to the ground, they begin to de- compose, and the carbon in them is slowly burned by the oxygen of the air, and is returned to the air as carbon dioxide. Vegeta- ble mould, however, does not decay quickly, so that the carbon of a fallen leaf may remain for years in the soil, as humus, before it can return to the air. Even when this time comes, the gas as it rises may be caught by neighboring plants, and its imprisonment is begun anew. In an early geological age, the Carboniferous, when the air was richer in carbon dioxide than it is now, and the moisture and temperature conditions were very favorable, trees grew to gigantic dimensions. Ferns and other low plants grew scores of feet in height. The vast forests of that age gathered much of the carbon from the air; and when they fell, immense layers of vegetable mould and other carbonaceous substances were formed. In time, as the earth destroyed old lands and created new continents, these deposits of carbon became imbedded in solid rock, and formed the coal deposits of the present day. The coal of our stoves repre- sents a portion of carbon arrested in its process of circulation. However, as soon as placed in the fire, it is ready to fly back into the air as carbon dioxide, in which condition it existed many thou- sands of years ago, before the relentless grasp of a plant leaf chained it in a plant cell. At times, portions of plant remains were buried under peculiarly favorable conditions of pressure and tem- perature, and the tiny atoms were forced to arrange themselves in

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such symmetrical ways that lustrous diamonds resulted. A dia- mond is but carbon arrested in one phase of its circulation. When man or animals intervene, the phases of the circulation of carbon are often increased in number. For instance, the oil stored in seeds is sometimes expressed, and used for purposes of lubrication or for fuel. Many substances obtained from plants, are converted by the subtle methods of the chemist, into brilliantly col- ored dyes, into valuable medicines, and it may be into articles for per- manent use —such as celluloid —and the circulation of the carbon found in these things, is delayed. Almost all organic substances contain carbon that is waiting for its liberation into its initial state. — The products of plant life sugar, starch, and flesh-form- oil,

ing elements —are eaten by animals. In the animal system, carbon undergoes changes that form interesting phases of its circulation. Sugar, for instance, passes from the stomach and intestines into the blood, and is carried from place to place in the body, until, in some part that is doing work, it is burned by the oxygen carried by the blood. In time, the carbon dioxide thus produced is carried by the blood to the lungs where it is breathed out into the atmos- phere, to begin over the cycle of its changes. The flesh-forming elements of plants, if eaten by man, are taken into the blood also, and may be changed into muscle, and may remain in the body for many years, until after death the carbon is again liberated. Thus we might follow carbon into the most distant corners of earth-life. Like water, it is rapidly, restlessly passing through the phases of its existence: the air, the plant or the animal, the soil, diamond, chemicals and air again. The story that the carbon of a spoonful of sugar might tell is as wonderful as the story of the drop of water. In the beginning, it helped to form a delicate plant growing on the shore of the primeval ocean; then part of a monster fish; then imprisoned in a coal mine until set free by a devastating fire; then part of a plant again; then part of the life blood of a prehistoric elephant; then free in the air again, and, now, after many cycles of changes, a part of a bit of sugar fed to an innocent child. This is not overdrawn it is possible.

The same law of circulation may be illustrated in the history of the mineral matters of the earth. In the beginning, the mineral

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substances formed only the rocks of the first mountains. Soon, however, the rains fell, and the rocks were pulverized, and the powder washed down into the rivers, and deposited on the ocean Then the ocean bed was raised above the water, :floor as a soft mud.

and became a mountain, and the soft mud became changed into hard rock by pressure and other forces. Then the rains and the frosts and the floods converted the new rock into powder, which this time perhaps was washed down into a valley to become fertile farm land. Plants growing upon this soil, fed upon the mineral matter, and made it a part of their structures. In time the plants decayed or were burned, and the mineral matter set free as ash, to become part of the soil again. Or, if the plants were eaten by animals, the mineral matters entered into the animal body, and re- mained there until, perhaps, the animal died, when they were finally returned to the soil. Then, perhaps, another convulsion passed over the earth, the soils sank under the water, and were brought up again as rock. Thus rock, in its circulation, passes through numerous phases: rock, mud, ocean-bed, rock, soils, plants, ani- mals, and rock again. Even the earth itself, as a unit, may be passing through a cycle of changes. It came from a larger body, of higher proper- ties, perhaps a sun; it was then degraded to its present condition,

and is now working onward to become a sun again. Thus instances could be multiplied in support of the law of the circulation of matter in nature. To be ever changing, ever repeating, ever moving around and around, but at the same time, spiral-like, onward — that is nature's decree for all matter. As has been before remarked, infinite variations of a few simple melo- dies constitute the great song of the universe.