Popular Science Monthly/Volume 3/August 1873/Lowly Vegetable Forms
|LOWLY VEGETABLE FORMS.|
By Rev. HUGH MACMILLAN.
LIFE is everywhere. "Nature lives" says Lewes; "every pore is bursting with life; every death is only a new birth; every grave a cradle." "The earth-dust of the universe," says Jean Paul, "is inspired by the breath of the great God. The world is brimming with life; every leaf on every tree is a land of spirits." The tendency to vegetate is a ceaseless power. It has been in operation from the earliest ages of the earth, ever since living beings were capable of existing upon its surface; and so active in the past history of the globe has been this tendency, that most of the superficial rocks of the earth's crust are composed of the remains of plants. It operates with undiminished and tireless energy still. Vegetation takes place upon almost every substance; upon the bark of trees, upon naked rocks, upon the roofs of houses, upon dead and living animal substances, upon glass when not constantly kept clean, and even on iron which had been subjected to a red heat a short time before. Zoologists tell us, when speaking of animalcules, that not a drop of stagnant water, not a speck of vegetable or animal tissue, not a portion of organic matter, but has its own appropriate inhabitants. The same may be said of plants; for we can hardly point to a single portion of the earth's surface which is not tenanted by some vegetable form whose structure is wonderfully adapted to its situation and requirements. Even in the hottest thermal springs, and on the eternal snows of the arctic regions, peculiar forms of vegetation have been found. From the deepest recesses of the earth to which the air can penetrate, to the summits of the loftiest mountains; from the almost unfathomable depths of the ocean to the highest clouds; from pole to pole, the vast stratum of vegetable life extends; while it ranges from a temperature of 35° to 135° Fahr., a range embracing almost every variety of conditions and circumstances.
The most cursory and superficial glance will recognize in every scene a class of plants whose singular appearances, habits, and modes of growth, so prominently distinguish them from the trees and flowers around, that they might seem hardly entitled to a place in the vegetable kingdom at all. On walls by the wayside, on rocks on the hills, and on trees in the woods, we see tiny green tufts and gray stains, or party-colored rosettes spreading themselves, easily dried by the heat of the sun, and easily revived by the rain. In almost every stream, lake, ditch, or any collection of standing or moving water, we observe a green, slimy matter, forming a scum on the surface, or floating in long filaments in the depths. On almost every fallen leaf and decayed branch, fleshy, gelatinous bodies of different forms and sizes meet our eye. Sometimes all these different objects appear growing on the same substance. If we examine a fallen, partially-decayed twig, half-buried in the earth in a wood, we may find it completely covered with various representatives of these different vegetable growths; and nothing surely can give us a more striking or convincing proof of the universal diffusion of life. All these different plants belong to the second great division of the vegetable kingdom, to which the name of Cryptogamia has been given, on account of the absence, in all the members, of those prominent organs which are essential to the production of perfect seed. They are propagated by little embryo plants called spores, or sporules, generally invisible to the naked eye, and differing from true seeds in germinating from any part of their surface instead of from two invariable points. Besides this grand distinguishing mark, they possess several other peculiar qualities in common. They consist of cells only, and hence are often called cellular plants, in contradistinction to those plants which are possessed of fibres and woody tissue. Their development is also superficial, growth taking place from the various terminal points; and hence they are called acrogens and thallogens, to distinguish them from monocotyledonous and dicotyledonous plants. Popularly, they are known as mosses, lichens, algae, and fungi. They open up a vast field of physiological research. They constitute a microcosm, a strange minute world underlying this great world of sense and sight, which, though unseen and unheeded by man, is yet ever in full and active operation around us. It is pleasant to turn aside for a while from the busy human world, with its ceaseless anxieties, sorrows, and labors, to avert our gaze from the splendors of forest and garden, from the visible display of green foliage and rainbow-colored blossoms around us, and contemplate the silent and wonderful economy of that other world of minute or invisible vegetation with which we are so mysteriously related, though we know it not. There is something exceedingly interesting in tracing Nature to her ultimate and simplest forms. The mind of man has a natural craving for the infinite. It delights to speculate either on the vast or the minute; and we are not surprised at the paradoxical remark of Linnæus, that Nature appeared to him greatest in her least productions.
These plants once occupied the foremost position in the economy of Nature. Like many decayed families whose founders were kings and mighty heroes, but whose descendants are beggars, they were once the aristocracy of the vegetable kingdom, though now reduced to the lowest ranks, and considered the canaille of vegetation. Geology reveals to us the extraordinary fact that one whole volume of the earth's stony book is filled almost exclusively with their history. Life may have been ushered upon our globe through oceans of the lowest types of Confervœ, long previous to the deposit of the oldest palaeozoic rocks as known to us; and for myriads of ages these extremely simple and minute plants may have represented the only idea of life on earth. But, passing from conjecture to the domain of established truth, we know of a certainty that, at least throughout the vast periods of the Carboniferous era, ferns, mosses, and still humbler plants, occupied the throne of the vegetable kingdom, and, by their countless numbers, their huge dimensions, and rank luxuriance, covered the whole earth with a closely-woven mantle of dark-green verdure—from Melville Island in the extreme north, to the islands of the Antarctic Ocean in the extreme south. The relics of these immense primeval forests, reduced to a carbonaceous or bituminous condition by the secret resources of Nature's laboratory, amid so many convulsions of the globe, are now buried deep in the bowels of the earth, packed into solid sandstone cases, and under huge shady covers, and stored up in the smallest compass by the mighty pressure of ponderous rock-presses, constituting the chief source of our domestic comfort, and of nearly all our commercial greatness. A coal-bed is, in fact, a hortus siccus of extinct cryptogamic vegetation, bringing before the imagination a vista of the ancient world, with which no arrangement of landscape or combination of scenery can now be compared; and, gazing upon its dusky contents, our minds are baffled in aiming to comprehend the bulk of original material, the seasons of successive growth, and the immeasurable years or ages which passed while decay, and maceration, and chemical changes, prepared the fallen vegetation for fuel. If the specimens of plants, thus strangely preserved, teach us one truth more than another, it is this, that size and development are terms of no meaning when applied to a low or a high type of organization. The Cryptogamia of the Old World, the earliest planting in the new-formed soil, are in bulk, as well as in elegance and beauty of form, unrivalled by the finest specimens of the modern forest. The little and the great, the recent and the extinct, were equally the objects of Nature's care, and were all modelled with a skill and finish that left nothing to be added.
And as in early geological epochs they occupied so conspicuous a position, so now in the annals of physical geography they are entitled to a prominent place. With the exception of the grasses—Nature's special favorites—they are the most abundant of all plants, possessing inconceivable myriads of individual representatives in every part of the globe, from which unfavorable conditions exclude all other vegetation; and thus they contribute, far more than we are apt from a superficial observation to imagine, to the picturesque and romantic appearances exhibited by scenery, and to the formation of that richly-woven and beautifully-decorated robe of vegetation which conceals the ghastly skeleton of the earth, and hides from our view the rugged outlines and primitive features of Nature. They are the first objects that clothe the naked rocks which rise above the surface of the ocean; and they are the last traces of vegetation which disappear under degrees of heat and cold fatal to all life. Their structure is so singularly varied and plastic, that they are adapted to every possible situation. In every country they form an important element in the number of plants, the proportion to flowering plants decreasing from and increasing toward the poles. Taking them as a whole, and in regard to their size, they occupy a larger area of the earth's surface than any other kind of vegetation. There are immense forests of trees here and there in different countries, realizing Cowper's wish for "a boundless contiguity of shade;" there are vast colonies of flowering plants; but the range of the most ubiquitous tree or flower is vastly inferior to that of some of the humblest lichens and mosses. Although these plants occupy but a very subsidiary and unimportant position among the vegetation which surrounds us in our daily walks, and are concealed in isolated patches in the woods and fields by the luxuriance of higher and more conspicuous plants, yet they constitute the sole vegetation of very extensive regions of the earth's surface. Every part of the globe, within a thousand feet of the line of perpetual snow, is redeemed from utter desolation by these plants alone. Above the valleys and the lower slopes which form the step of transition from plain to mountain—inhabited by prosperous and civilized nations—is the domain of mist and mystery, the region of storm—a world which is not of this world, where God and Nature are all in all, and man is nothing; and in this unknown region there are immense tracts familiar to the eye of wild bird, to the summer cloud, the stars and meteors of the night—strange to human faces and the sound of human voices, where the lichen and the moss alone luxuriate and carpet the sterile ground. The grandest and sublimest regions of the earth are adorned with garlands of the minutest and humblest plants; they are the tapestry, the highly-wrought carpeting laid down in the vestibules of Nature's palaces. If we look at a map of the world, we see that Europe and Asia are held together as it were by a huge ridge or backbone of mountain-elevation, which, although suffering partial interruption, may be roughly described as continuous from one ocean to another. It begins with the mountains of Biscay in Spain, passes on through the Pyrenees, with a slight interruption, into the Alps, which throw off the important spur or rib of the Apennines; thence it divides into the Balkan and Carpathians. We trace the chain next in the Caucasus and the mountains of Armenia—with the interruption of the Caspian Sea—passing into the Hindoo Coosh and the Himalaya Mountains, whence the chain forks and takes a direction north and south, enclosing like walls the whole delta of China, and thence dips into the eastern ocean. In Africa also, at its widest part, there is a similar backbone, beginning not far from Sierra Leone, and losing itself in the east in the mountains of Abyssinia; while in America the mountain-spine trends north and south from the Hudson's Bay territories, through the Rocky Mountains, uninterruptedly through the Isthmus of Panama, along the Andes to the Straits of Magellan. These vast mountain-systems, with their culminating regions in the Andes, Alps, and Himalayas, and their subsidiary branches or ribs in the Grampians, Dovrefields, Ural, and Atlantic ranges, are clothed on their sides, summits, and elevated plateaus, almost exclusively with cryptogamic vegetation, and enable us to form some conception of the immense altitudinal range of these plants. Then there are whole islands in the Arctic and Antarctic Oceans whose vegetation also is almost entirely cellular. The northern portion of Lapland, the continent of Greenland, the large islands of Spitzbergen, Nova Zembla, and Iceland, the extensive territories of the Hudson's Bay Company, the enormous tracts of level land which border the Polar Ocean from the North Cape to Behring's Straits, across the north of Europe and Asia, and from Behring's Straits to Greenland, across the north of America, a stretch of many thousands of miles; all these immense areas of the earth's surface—where not a tree, nor a shrub, nor a flower is seen, except the creeping arctic willow and birch, and the stunted moss-like saxifrage and scurvy-grass—are covered with fields of lichens and mosses, far exceeding any thing that can be compared in that respect among phanerogamous plants. Thus, to the rugged magnificence of Alpine scenery, and the dreary isolation and uniformity of the arctic steppes, and the boundless wastes of brown desert and misty moorland, to these great outlets from civilization and the tameness of ordinary life, which allow the soul to expand and go out in sublime imaginings toward the infinity of God, these humble plants form the sole embellishments.
So much for the distribution of these plants on the land; their range in the waters is still more extensive. Lichens and mosses cover the waste surfaces of the earth; diatoms and confervas are everywhere miraculously abundant in the waters—in rivers and streams, in ditches and ponds, alike under the sunny skies of the south, and in the frozen regions of the north; on the surface of the sea in floating meadows, and in the dark and dismal recesses of the ocean only to be explored by the long line of the sounding-lead. The ocean swarms with innumerable varieties, without their presence being indicated by any discoloration of the fluid. The Arctic and Antarctic Oceans, covering areas larger than the Continents of Europe and Asia, are peopled by myriads of diatoms; various inland seas and lakes are tinged of different hues by their predominance in the waters; while it has been ascertained, from the soundings obtained during the investigations connected with laying the electric telegraph-cable between Ireland and Newfoundland, that the floor of the Atlantic is paved many feet deep with their silicious shields, preserving in all their integrity their wonderful shapes, notwithstanding their extreme delicacy and minuteness, and the enormous pressure of the vast body of water which rests above them. Such is the wide space which these organisms occupy in the fields of Nature—a prominence which is surely sufficient to redeem them from the charge of insignificance. They are inferior in majesty of form to palms and oaks, but in their united influence it is not too extravagant to say that they are not less important than the great forests of the world.
This vast profusion of minute and humble vegetable life serves the obvious purpose of preparing the way for higher orders of vegetation. Nature is incessantly working out vast ends by humble and scarcely recognizable means. The features of the earth are being continually altered by the germination and dispersion of the algae, mosses, and lichens. Bare and sterile mountains are clothed with verdure; rocks are mouldering into soil; seas are filling up; rivers and streams are continually shifting their outlines; and lakes are converted into fertile meadows and the sites of luxuriant forests, by means of the vast armies of Nature's pioneers. Hard inorganic matters are reduced to impalpable atoms; waters and gases are decomposed and moulded into new forms and substances having new properties, by vegetable growth. Minute as these plants are, they are intimately related to the giant forms of the universe. It has been observed that as the great whole is indissolubly connected with its minutest parts, so the germination of the minutest lichen and the growth of the simplest moss are directly linked with the grandest astronomical phenomena; nor could the smallest fungus or conferva be annihilated without destroying the equilibrium of the universe. It is with organic Nature as with the body politic or the microcosm of the human frame, if "one member suffer all the members suffer with it," and the loss of one class or order would involve that of another, till all would perish. Our comfort and health, nay our very existence, more or less immediately depend on the useful functions which they perform. Before we can have the wheat which forms our daily bread, or the grass which yields us, through the instrumentality of our herds, our daily supply of animal food, or the cotton and lint which form our clothes, countless generations of lichens and mosses must have been at work preparing a soil for the growth of the plants which produce these useful materials. And as on the dry land, so in the great waters, this wonderful chain of connection exists in all its complexity. Before the reader can peruse these pages by the light of the midnight lamp, or the gay party can indulge their revels under the brilliant glare of spermaceti tapers, myriads of minute diatoms and Confervœ, floating in the waters of the sea, must have formed a basis of subsistence for the whales and seals whose oil is employed for these purposes. Man's own structure is nourished and built up by the particles which these active plants have rescued from the mineral kingdom, and which once circulated through their simple cells; and thus the highest and most complex creature, by a vital sympathy and a close physical relation, is connected with the lowest and simplest organism, to teach him humility, and inspire him with a deep interest in all the works of his Maker!
"Nothing in this world is single;
All things, by a law divine,
In one another's being mingle."
It may be asked by a class of individuals, unfortunately too numerous, What is the use of these minute plants? In the business language of the world things are called useful when they promote the profit, convenience, or comfort, of every-day life; and useless when they do not promote, or when they hinder, either of these desired ends. But this definition is extremely partial and one-sided. There are higher purposes to serve in this world than mere subservience to the physical wants of man. There is a much higher utility than the mere temporary and worldly one. The useful things of external life, indeed, should not be undervalued; they are the first things required, but they are not the sole or the highest things necessary. Man must have food and clothing in order to live; but it must also be remembered that man does not live by bread and the conveniences of external life alone. When any one does live by these alone, he has forfeited his claim to the higher form of life which is his glorious privilege, and by which he is distinguished from the lower animals. Nature throughout her whole wide domains gives no countenance to such a materialistic exclusiveness. She is at once utilitarian and transcendental. Uses and beauties intermingle. All that is useful is around us; but how much more is there besides? There is a strange superfluous glory in the summer air; there is marvellous beauty in the forms and hues of flowers; there is an enchanting sweetness in the song of birds and the murmur of waters; there are a divine grandeur and loveliness in the landscapes of earth and the scenery of the heavens, the changes of the seasons, the dissolving splendors of morning, noon, sunset, and night, utterly incomprehensible upon the theory of Nature's exclusive utilitarianism. "The tree which shades the wayfarer in the noontide heat adorns the landscape; and the flower which gives honey to the bee sheds its perfume on the air. A leaf no less than a flower fulfils the functions of life, ministers to the necessities of man, yet clothes itself, and adorns the earth in tapestries richer than the robes of kings." All things proclaim that the Divine Architect, while amply providing for the physical wants of his creatures, has not forgotten their spiritual necessities and enjoyments; and, having implanted in the human soul a yearning for the beautiful, has surrounded us with a thousand objects by whose charms that yearning may be gratified. And one of the most striking examples of this Divine care is to be seen in the profusion of minute objects spread around us, which apparently have no direct influence at all upon man's physical nature, and have no connection with his corporeal necessities. These objects, subserving no gross utilitarian purpose, are intended to educate man's spiritual faculties by the beauties of form, the wonders of structure, and the adaptations of economy which they display. Their beauty is sufficient reason for their existence, were there no other. When their varied and exquisitely symmetrical forms are presented to the eye under the microscope, a thrill of pleasure is experienced, calm and pure, because free from all taint of passion, and felt all the more intensely because nameless and indefinite. We are brought face to face with perfection in its most wonderful aspect—the perfection of minuteness and detail; with objects which bear most deeply impressed upon them the signet-mark of their Maker; and we observe with speechless admiration that the Divine attention is acuminated and his skill concentrated on these vital atoms; the last visible organism vanishing from our view with the same Divine glory upon it, as the last star that glimmers out of sight on the remotest verge of space.
These organisms further justify their existence to the utilitarian, inasmuch as their study is well calculated to exercise an educational influence which should not be overlooked or despised. While they try the patience, they exercise the faculties by forcing attention upon details. Their minuteness, their general resemblance to each other, their want in many cases of very prominent or marked characteristics, render it a somewhat difficult task to identify them. Long hours may often be spent in ascertaining the name of a single species, and assigning it its proper place in the tribe to which it belongs. One species may often be confounded with another closely allied, and days and weeks may elapse before the eye and the mind, familiarized with their respective details, can observe the distinctions between them. This difficulty of identification greatly sharpens one's knowledge, induces a habit of paying attention to minutiae, and creates a power of distinguishing between things that differ slightly, which is exceedingly valuable and important. For the eye and mind thus educated to detect resemblances and differences in objects, which to ordinary observation appear widely dissimilar or precisely the same, there will be abundant scope in the practical details of common every-day life, as well as in the higher walks of literature, science, and art.
The study of these plants has also a tendency to elevate and enlarge our conceptions of Nature; its vastness and complexity, its incommunicable grandeur, its all but infinity, opening before us newer and more striking vistas with every descending step we take. The farther we advance, and the wider our sphere of observation extends, wonder follows on wonder, till our faculties become bewildered, and our intellect falls back on itself in utter hopelessness of arriving at the end. Minute as the objects are in themselves, contact with them cannot fail to excite the mind, to call it forth into full and vigorous exercise, to enlist its sympathies, and to expand its faculties. Many eloquent pages have been written to show this elevating influence upon the mind, of contact with and contemplation of the phenomena of Nature; but it is not the great and sublime objects of Nature alone that produce this effect—the sublimity of mountains, the majesty of rivers, and the repose of forests—the very humblest and simplest objects are calculated to awaken these emotions in a yet higher and purer form. "The microscope," as Mr. Lewes has well observed, "is not the mere extension of a faculty; it is a new sense."
There are also peculiar pleasures connected with the study of these objects. There is, first, the pleasure of novelty and discovery—of exploring a realm where every thing is comparatively new, and every step is delightful; where the forms are unfamiliar, and the modes of life hitherto unimagined. There is, next, the more subtle and refined pleasure of observing the strange truths which they unfold, the beautiful laws which they reveal, and the resemblances and relations which they display. The false romanticism of vulgar fancy requires something pretentious and unnatural to gratify its taste; but, to the true poetical mind, the humblest moss on the wall, or the green slime that creams on the wayside pool, will suggest trains of pleasing and profitable reflection. He who has an observing eye and an appreciating mind for these minute wonders of Nature, need never be alone. Every nook and corner of the earth, however barren and dreary to superficial minds, has companions for him; and on every path he will find what the Indians call a rustawallah, a delightful road-fellow.
To the cryptogamic botanist Nature reveals herself in her wildest, and also in her fairest aspects. He enters into her guarded retreats—retiring spots of luxuriant, refreshing, and enticing beauty, that are hidden from every other eye; where the great world of strife and toil speaks not, and its cares and sorrows are forgotten, and Nature wakes up the dead divinity within, and rouses the soul to purer and nobler purposes. The peculiar haunts of the objects of his search are found on the sides and summits of lofty mountains, amid the dark, lonely recesses of forests; in the bright bosom of rivers, and lakes, and water-falls; on far-off, unvisited moors, where heaven's serene and passionless blue is the only thing of beauty; and in the mossy retreats of dell and dingle, where Titania and her fays might sport away the dreamy noontide hours. There he finds the pictures which the soul treasures most lovingly; and in these by-ways does he gain the truest insight into the mysteries of life. In thus penetrating into the very heart of Nature, with much toil and exertion it may be, he seems to win her confidence, and to earn the right to look into her areana. By minute contact and continued commune with her alone in the wilderness, he feels in all its fulness and depth the beautiful relationship that exists between the outer and the inner life of creation. To others the landscape may be the mere background of a picture, in the foreground of which human figures are acting; to him its charms are agencies and influences acting on his heart and mingling with his life. The sportsman in search of game frequently wanders into regions that seem primeval in their solitude, and where "human foot had ne'er or rarely been;" but so absorbing is the pursuit in which he is engaged, that he seldom pauses to watch the features of the surrounding scenery, or to notice combinations of objects and effects of light and shade which Nature never displays, except in such unfrequented spots. But to the cryptogamist, on the other hand, these very scenes of Nature lend a nameless charm and interest to the lowly plants he gathers, and are ever after indelibly associated with them in his memory, and are renewed every time he witnesses their faded remains. Hardly a moment passes over the solitary collector amid such secluded scenes, without some grand effect being produced in the surrounding landscape, or in the appearance of the sky above him; some wonderful transformation of Nature, as though the spot where he stands were her tiring-room, and she were trying on robe after robe to see which became her best; some striking incident, which might well inspire him with the wish to catch the happy moment, and give it a permanent existence. Such are the simple, refining, and enduring pleasures which the cryptogamic botanist enjoys in the pursuit of his favorite study amid the scenes of Nature.
Add to all these recommendations this last important advantage, that these plants can be observed and collected without interruption throughout the whole year, and in situations where other vegetation is reduced to zero. They can be studied alike under the cloudy skies of December, as when illumined by the sunshine of June. When the flowers and ferns have vanished, when the lights are fled, and the garlands are dead, the deserted banquet-hall of Flora is still relieved by the presence of these humble retainers, whose fidelity is proof against every change of circumstance, and whose better qualities are displayed when the storm is wildest and the desolation most complete. They are no summer friends. As Ruskin has beautifully observed: "Unfading as motionless, the worm frets them not, and the autumn wastes not. Strong in lowliness, they neither blanch in heat, nor pine in frost. To them, slow-fingered, constant-hearted, is intrusted the weaving of the dark eternal tapestries of the hills; to them, slow-pencilled, iris-dyed, the tender framing of their endless imagery. Sharing the stillness of the unimpassioned rock, they share also its endurance; and while the winds of departing spring scatter the white hawthorn-blossoms like drifted snow, and summer duns in the parched meadow the drooping of its cowslip gold, far above among the mountains, the silver lichen-spots rest, starlike on the stone, and the gathering orange-stain upon the edge of yonder western peak reflects the sunsets of a thousand years."—Foot-Notes from the Page of Nature.