THE MYSTERIES OF A FLOWER.

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BY PROFESSOR R. HUNT.

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Flowers have been called the stars of the earth; and certainly, when we examine those beautiful creations, and discover them, analyzing the sunbeam, and sending back to the eye the full luxury of colored light, we must confess that there is more real appropriateness in the term than even the poet who conceived the delicate thought imagined. Lavoisier beautifully said—“The fable of Prometheus is but the outshadowing of a philosophic truth—where there is light there is organization and life; where light cannot penetrate, Death for ever holds his silent court.” The flowers, and, indeed, those far inferior forms of organic vegetable life which never flower, are direct dependencies on the solar rays. Through every stage of existence they are excited by those subtle agencies which are gathered together in the sunbeam; and to these influences we may trace all that beauty of development which prevails throughout the vegetable world. How few there are, of even those refined minds to whom flowers are more than a symmetric arrangement of petals harmoniously colored, who think of the secret agencies forever exciting the life which is within their cells, to produce the organized structure—who reflect on the deep, yet divine philosophy, which may be read in every leaf:—those tongues in trees, which tell us of Eternal goodness and order.

The hurry of the present age is not well suited to the contemplative mind; yet, with all, there must be hours in which to fall back into the repose of quiet thought becomes a luxury. The nervous system is strung to endure only a given amount of excitement; if its vibrations are quickened beyond this measure, the delicate harp-strings are broken, or they undulate in throbs. To every one the contemplation of natural phenomena will be found to induce that repose which gives vigor to the mind—as sleep restores the energies of a toil-exhausted body. And to show the advantages of such a study, and the interesting lessons which are to be learned in the fields of nature, is the purpose of the present essay.

The flower is regarded as the full development of vegetable growth; and the consideration of its mysteries naturally involves a careful examination of the life of a plant, from the seed placed in the soil to its full maturity, whether it be as herb or tree.

For the perfect understanding of the physical conditions under which vegetable life is carried on, it is necessary to appreciate, in its fullness, the value of the term growth. It has been said that stones grow—that the formation of crystals was an analogous process to the formation of a leaf; and this impression has appeared to be somewhat confirmed by witnessing the variety of arborescent forms into which solidifying waters pass, when the external cold spreads it as ice over our window-panes. This is, however, a great error; stones do not grow—there is no analogy even between the formation of a crystal and the growth of a leaf. All inorganic masses increase in size only by the accretion of particles—layer upon layer, without any chemical change taking place as an essentiality. The sun may shine for ages upon a stone without quickening it into life, changing its constitution, or adding to its mass. Organic matter consists of arrangements of cells or sacs, and the increase in size is due to the absorption of gaseous matter, through the fine tissue of which they are composed. The gas—a compound of carbon and oxygen—is decomposed by the excitement induced by light; and the solid matter thus obtained is employed in building a new cell—or producing actual growth, a true function of life, in all the processes of which matter is constantly undergoing chemical change.

The simplest developments of vegetable life are the formation of confervæ upon water, and of lichens upon the surface of the rock. In chemical constitution, these present no very remarkable differences from the cultivated flower which adorns our garden, or the tree which has risen in its pride amidst the changing seasons of many centuries. Each alike have derived their solid constituents from the atmosphere, and the chemical changes in all are equally dependent upon the powers which have their mysterious origin in the great centre of our planetary system.

Without dwelling upon the processes which take place in the lower forms of vegetable life, the purposes of this essay will be fully answered by taking an example from amongst the higher class of plants and examining its conditions, from the germination of the seed to the full development of the flower—rich in form, color, and odor.

In the seed-cell we find, by minute examination, the embryo of the future plant carefully preserved in its envelop of starch and gluten. The investigations which have been carried on upon the vitality of seeds appear to prove that, under favorable conditions, this life-germ may be maintained for centuries. Grains of wheat, which had been found in the hands of an Egyptian mummy, germinated and grew; these grains were produced, in all probability, more than three thousand years since; they had been placed, at her burial, in the hands of a priestess of Isis, and in the deep repose of the Egyptian catacomb were preserved to tell us, in the eighteenth century, the story of that wheat which Joseph sold to his brethren.

The process of germination is essentially a chemical one. The seed is placed in the soil, excluded from the light, supplied with a due quantity of moisture, and maintained at a certain temperature, which must be above that at which water freezes; air must have free access to the seed, which if placed so deep in the soil as to prevent the permeation of the atmosphere never germinates. Under favorable circumstances, the life-quickening processes begin; the starch, which is a compound of carbon and oxygen, is converted into sugar by the absorption of another equivalent of oxygen from the air; and we have an evident proof of this change in the sweetness which most seeds acquire in the process, the most familiar example of which we have in the conversion of barley into malt. The sugar thus formed furnishes the food to the now living creation, which, in a short period, shoots its first leaves above the soil; and these, which rising from their dark chamber are white, quickly become green under the operations of light.

In the process of germination a species of slow combustion takes place, and—as in the chemical processes of animal life and in those of active ignition—carbonic acid gas, composed of oxygen and charcoal, or carbon, is evolved. Thus, by a mystery which our science does not enable us to reach, the spark of life is kindled—life commences its work—the plant grows. The first conditions of vegetable growth are, therefore, singularly similar to those which are found to prevail in the animal economy. The leaf-bud is no sooner above the soil than a new set of conditions begin; the plant takes carbonic acid from the atmosphere, and having, in virtue of its vitality, by the agency of luminous power, decomposed this gas, it retains the carbon, and pours forth the oxygen to the air. This process is stated to be a function of vitality; but as this has been variously described by different authors, it is important to state with some minuteness what does really take place.

The plant absorbs carbonic acid from the atmosphere through the under surfaces of the leaves, and the whole of the bark; it at the same time derives an additional portion from the moisture which is taken up by the roots, and conveyed “to the topmost twig” by the force of capillary attraction, and another power, called endosmosis, which is exerted in a most striking manner by living organic tissues. This mysterious force is shown in a pleasing way by covering some spirits of wine and water in a wine-glass with a piece of bladder; the water will escape, leaving the strong spirit behind.

Independently of the action of light the plant may be regarded as a mere machine; the fluids and gases which it absorbs, pass off in a condition but very little changed—just as water would strain through a sponge or a porous stone. The consequence of this is the blanching or etiolation of the plant, which we produce by our artificial treatment of celery and sea-kale—the formation of the carbonaceous compound called chlorophyle, which is the green coloring-matter of the leaves, being entirely checked in darkness. If such a plant is brought into the light, its dormant powers are awakened, and, instead of being little other than a sponge through which fluids circulate, it exerts most remarkable chemical powers; the carbonic acid of the air and water is decomposed; its charcoal is retained to add to the wood of the plant, and the oxygen is set free again to the atmosphere. In this process is exhibited one of the most beautiful illustrations of the harmony which prevails through all the great phenomena of nature with which we are acquainted—the mutual dependence of the vegetable and animal kingdoms.

In the animal economy there is a constant production of carbonic acid, and the beautiful vegetable kingdom, spread over the earth in such infinite variety, requires this carbonic acid for its support. Constantly removing from the air the pernicious agent produced by the animal world, and giving back that oxygen which is required as the life-quickening element by the animal races, the balance of affinities is constantly maintained by the phenomena of vegetable growth. This interesting inquiry will form the subject of another essay.

The decomposition of carbonic acid is directly dependent upon luminous agency; from the impact of the earliest morning ray to the period when the sun reaches the zenith, the excitation of that vegetable vitality by which the chemical change is effected regularly increases. As the solar orb sinks toward the horizon the chemical activity diminishes—the sun sets—the action is reduced to its minimum—the plant, in the repose of darkness, passes to that state of rest which is as necessary to the vegetating races as sleep is to the wearied animal.

These are two well-marked stages in the life of a plant, germination and vegetation are exerted under different conditions; the time of flowering arrives, and another change occurs, the processes of forming the alkaline and acid juices, of producing the oil, wax, and resin, and of secreting those nitrogenous compounds which are found in the seed, are in full activity. Carbonic acid is now evolved and oxygen is retained; hydrogen and nitrogen are also forced, as it were, into combination with the oxygen and carbon, and altogether new and more complicated operations are in activity.

Such are the phenomena of vegetable life which the researches of our philosophers have developed. This curious order—this regular progression—showing itself at well-marked epochs, is now known to be dependent upon solar influences; the

“Bright effluence of bright essence increate”

works its mysterious wonders on every organic form. Much is still involved in mystery; but to the call of science some strange truths have been made manifest to man, and of some of these the phenomena must now be explained.

Germination is a chemical change which takes place most readily in darkness; vegetable growth is due to the secretion of carbon under the agency of light; and the processes of floriation are shown to involve some new and compound operations: these three states must be distinctly appreciated.

The sunbeam comes to us as a flood of pellucid light, usually colorless; if we disturb this white beam, as by compelling it to pass through a triangular piece of glass, we break it up into colored bands, which we call the spectrum, in which we have such an order of chromatic rays as are seen in the rainbow of a summer shower. These colored rays are now known to be the sources of all the tints by which nature adorns the surface of the earth, or art imitates, in its desire to create the beautiful. These colored bands have not the same illuminating power, nor do they possess the same heat-giving property. The yellow rays give the most LIGHT; the red rays have the function of HEAT in the highest degree. Beyond these properties the sunbeam possesses another, which is the power of producing CHEMICAL CHANGE—of effecting those magical results which we witness in the photographic processes, by which the beams illuminating any object are made to delineate it upon the prepared tablet of the artist.

It has been suspected that these three phenomena are not due to the same agency, but that, associated in the sunbeam, we have LIGHT, producing all the blessings of vision, and throwing the veil of color over all things—HEAT, maintaining that temperature over our globe which is necessary to the perfection of living organisms—and a third principle, ACTINISM, by which the chemical changes alluded to are effected. We possess the power, by the use of colored media, of separating these principles from each other, and of analyzing their effects. A yellow glass allows light to pass through it most freely, but it obstructs actinism almost entirely; a deep-blue glass, on the contrary, prevents the permeation of light, but it offers no interruption to the actinic, or chemical rays; a red glass, again, cuts off most of the rays, except those which have peculiarly a calorific, or heat-giving power.

With this knowledge we proceed in our experiments, and learn some of the mysteries of nature’s chemistry. If, above the soil in which the seed is placed, we fix a deep, pure yellow glass, the chemical change which marks germination is prevented; if, on the contrary, we employ a blue one, it is greatly accelerated; seeds, indeed, placed beneath the soil, covered with a cobalt blue finger-glass, will germinate many days sooner than such as may be exposed to the ordinary influences of sunshine:—this proves the necessity of the principle actinism to this first stage of vegetable life. Plants, however, made to grow under the influences of such blue media present much the same conditions as those which are reared in the dark; they are succulent instead of woody, and have yellow leaves and white stalks—indeed, the formation of leaves is prevented, and all the vital energy of the plant is exerted in the production of stalk. The chemical principle of the sun’s rays, alone, is not therefore sufficient; remove the plant to the influence of light, as separated from actinism, by the action of yellow media, and wood is formed abundantly—the plant grows most healthfully, and the leaves assume that dark green which belongs to tropical climes or to our most brilliant summers. Light is thus proved to be the exciting agent in effecting those chemical decompositions which have already been described; but under the influence of isolated light it is found that plants will not flower. When, however, the subject of our experiment is brought under the influence of a red glass, particularly of that variety in which a beautifully pure red is produced by oxide of gold, the whole process of floriation and the perfection of the seed is accomplished.

Careful and long-continued observations have proved that in the spring, when the process of germination is most active, the chemical rays are the most abundant in the sunbeam. As the summer advances, light, relatively to the other forces, is largely increased: at this season the trees of the forest, the herb of the valley, and the cultivated plants which adorn our dwellings, are all alike adding to their wood. Autumn comes on, and then heat, so necessary for ripening grain, is found to exist in considerable excess. It is curious, too, that the autumnal heat has properties peculiarly its own—so decidedly distinguished from the ordinary heat, that Sir John Herschel and Mrs. Somerville have adopted a term to distinguish it. The peculiar browning or scorching rays of autumn are called the parathermic rays: they possess a remarkable chemical action added to their calorific one; and to this is due those complicated phenomena already briefly described.

In these experiments, carefully tried, we are enabled to imitate the conditions of nature, and supply, at any time, those states of solar radiation which belong to the varying seasons of the year.

Such is a rapid sketch of the mysteries of a flower; “Consider the lilies of the field, how they grow; they toil not, neither do they spin; and yet I say unto you, Solomon in all his glory was not arrayed like one of these.”

Under the influence of the sunbeam, vegetable life is awakened, continued, and completed; a wondrous alchemy is effected; the change in the condition of the solar radiations determines the varying conditions of vegetable vitality; and in its progress those transmutations occur, which at once give beauty to the exterior world, and provide for the animal races the food by which their existence is maintained. The contemplation of influences such as these realizes in the human soul that sweet feeling which, with Keats, finds that

A thing of beauty is a joy forever;

Its loveliness increasing, it will never

Pass into nothingness, but still will keep

A bower quiet for us, and a sleep

Full of sweet dreams, and health, and quiet breathing.

* * * * *

Such the sun and moon,

Trees old and young, sprouting a shady boon

For simple sheep; and such are daffodils,

With the green world they live in.