BY DONALD CULROSS PEATTIE
THERE is morning light here, shafting down through the live oaks in smoky beams. After the night’s rain that washed away a six-month summer dust, the little dark leaves gleam and twinkle. Softened, the brilliant sunshine is released by them to the fronds of the tree ferns that grow below, outstaying their day by geologic ages.
Never so beckoned the green world, or the sky or the sea. A mile or more beyond and below the live oaks the Pacific glitters, marked near the shore by a purple streak of shadow in its azure, that is giant seaweed anchored there, a floating breakwater from the bottoms.
To the east, toward the breadth of the continent, the mountains rise. I see, beyond the walled garden outside my study window, their arid ranges, where canyons are carven, looking deceptively easy of ascent. The white-limbed sycamores, at least, troop up them, winternaked now and clearly seen across this western distance. Higher in the peaks, I know, the cedars and firs begin; higher still, cold lakes are mirroring the bigcone pines, the greatest in the world.
Close at hand the wild tangle of the chaparral, sun-baked, sends up a pillar of incense. All of the life that is not ours, the other half, by which and with which we the animal life share earth, holds up its hands to the sunshine.
As the brain of man is the speck of dust in the universe that thinks, so the leaves—the fern and the needled pine and the latticed frond and the seaweed ribbon—perceive the light in a fundamental and constructive sense. The flowers looking in from the walled garden through my window do not, it is true, see me. But their leaves see the light, as my eyes can never do. They take it, as it forever spills away radiant into space in a golden wraste, to a primal purpose. They impound its stellar energy, and w ith that force they make life out of the elements. They breathe upon the dust, and it is a rose.
This serene sister life, this green society, was here before us; we are wholly dependent upon it; it reaches farther over and into our common earth and leaves a deeper imprint there than we do or our fellow’ creatures. On icy peaks the sprawling crustose lichen clings where even a mountain goat would gasp and stumble. Roots, following a thread-form water vein into the ground, will penetrate where it profits no beast to burrow. By the billion of billions the little jeweled diatoms float in the arctic seas, forming the basic food of all that swims. Where there is rain, the forests rise in their tiered solemnity; where rain falls scant, the hollow steppes brim with mobile grass, to the half of a continent. In the crevices of sternly naked cliffs, lowly plants wedge their soft bodies, secrete their tiny acids, and so, etching, leaching, prying, and prizing their way, they are among the forces that literally move mountains. They may in time degrade those heights and mollify their sterility. They can themselves become rock and lay down geologic strata. The iron ranges of Minnesota, the Pennsylvania seam of bituminous coal, limestone of Bermuda, chalk rock under the city of Richmond—all once were within the cell wall of a plant.
Copyright 1930, by The Atlantic Monthly Company, Boston, Mass. All rights reserved.
These are the larger movements; they are hard facts such as a man’s mind can entertain with satisfaction. When he walks in the woods, he becomes aware of something further, that escapes him. If he looks, if he listens, he begins to guess how behind the summer glitter of the leaves the sinews and pulls of great forces must be tensed and laxed, in all that relentless living. He sets a first footstep into the plant kingdom.
There are always some of us, not a few, in every generation, who go over wholly to the green flag. It is such a passionless fealty, so reticent a love, that neither do trumpets sound for it nor quarrels arise from it. Only, you will find that those who have pledged allegiance are happy about it in quiet.
The plantsman may begin as a gardener, or as an admirer and patriot of trees. Or his interest may have been captivated by the traffic that goes on in the strange plant stuffs of earth, fibre and gum and essential oils. Or he may simply see what, when I was a boy, I saw with longing—that the very weeds would go along companionably, if I could name them. And that a tree on the king’s land would be mine, if I knew how the sap got up in it in spring.
To travel in the plant kingdom, I wanted to know the language. It is a living language, with a precise grammar, intimately inflected, colored by overtones of meaning. It has, if you listen for it, a lovely fall upon the ear. I bought a grammar of it, a botany manual, and kept it secretly in my desk drawer, in that high New York office where my work, my first job, was something very different and much duller. That book was severely technical; I did not a quarter understand it, not did I recognize any of the flowers that it described.
But they grew, the book said, ‘by cold springs in deep mountain woods,’ ‘on high prairies,’ ‘in cypress “bottoms,”’ or ‘through the oak openings of Kentucky.’ Sometimes an exotic was to be ‘found on ballast about Atlantic seaports, naturalized from Asia,’ or else ‘escaped from old gardens to ditches and fallow fields.’ Grandly our native species would range ‘from Old Point Comfort to the Florida Keys, and south through the Antilles to Trinidad.’ They clung to a stony foothold ‘on serpentine outcrops from the Baie des Chaleurs to the northern shore of Lake Superior, and far to the north and westward.’ They went where I — discounting reason and the precepts of economic morality — determined too to go, ‘south on the mountains, to the high peaks of the Blue Ridge and the Great Smokies.’
On a day black with the icy conviction of March rain, my train was shot under the Hudson and up over the Jersey marshes where the dead reed grass bowed down in long sad lines. My heart was not light yet, here where a hard and ugly way prevailing made guilt out of any other. As the big smoky cities rolled like unlovely beads off the thread of the tracks, I thought how everywhere, in Elizabeth and Trenton, in Wilmington and Baltimore, young men, and old, and women, were all at work, where those lights burning by day pricked through the rain. All holding jobs and grateful for them as a punished boy for supper thrust through the door. And I was going south, running away.
In the night I woke because the train had stopped. Perhaps it was somewhere near the foot of the Craggies; I heard the roar of a mountain river, and a higher frailer sound above the churning water, the singing of a forest in the night wind.
I wondered if these were hemlocks swinging incense boughs, or knotted pines blistered with lakes of resin. Somewhere, in the loftier peaks, there must be black spruces too, and shebalsams, dripping the breath of health. These the nobles; I thought of what humbly grows between their roots, club moss and oxalis and wild ginger whose little spotted jug flowers lie buried to the lip. That river must have risen from icy springs under the balsams; already it was rushing toward the sea, to the low country of the long-leaf pine and palmetto. I was over the frontier unchallenged.
By noon of the next day the threeleaved windflower lay in the pages of my manual where I had traced it down to its description and its range ‘ in cool woods, south along the mountains to Carolina.’
In the coves, the high glens barred with rock and fallen log, there linger still in the Appalachians the last remnants of an ancient Tertiary flora that to-day survives only there and in the mountains of Japan and China. It ranges, to be sure, all over our eastern states, but the farther you leave the Carolinas behind, the less there is of it. In the southern highlands it is concentrated, carried out, as the mathematicians say, to a higher power. Nearly free of intrusive nondescript elements and vagabond weeds, it forms an entity discrete, descript. It is an aristocratic plant society, to which nothing can be added now unless you first make a place for it by destroying something irreplaceable.
I shall never be done with the catalogue of that aristocracy, begun that year — it was twenty ago. I followed the spring as it marched triumphantly north, working my way along the wall of the Blue Ridge (haughtily skirting west of the cities, through the Catskills) till the trail ended in asters stiff with autumn frost, in the White Mountains of New Hampshire.
Collecting, identifying, drawing, I had passed over the surface of things. I knew I would do no better were I to go, as I was, to the Virgin Islands (which I seriously contemplated) or to inconceivable Nepal.
In the lovely midst of that green kingdom I found that I was lost. I could go no further; the wall of the woods rose thorny before me. When you lose heart, you believe what other people will tell you is right for you. So I started back for New York to look for another job. Changing trains in Boston, I stopped over and went out to Cambridge to see the glass flowers in Agassiz Museum.
Here, swelled like a bubble, were the inner secrets of floral structure. Here in giant lucidity were all the forms of flowers, the variations upon simple numerological symmetries which human imagination could never have conceived. Here were the families, marshaled into their cohorts, rising from duckweed to the sunflower. You could follow the thread of any one of many guiding ideas in their evolution — pollen’s progress from the wind-borne golden spores of the pine with their great air sacs, to the pellets, intricately devised, by which the orchid stakes all upon a single insect transport. Or you could give a whole day to wonder at the ovaries, cross-sectioned and cut lengthwise, showing how ovules stand, stacked in rows as if by a purposive hand, awaiting the potent moment of fertilization when the pollen tubes tunnel through their prison to them.
My path was under my feet again.
Harvard was already at its first classes; they were overfull. But a berth for New York went empty out of South Station that night. The young man who might have gone that road stood on the rainy porch of the professor who had written that manual once hidden in the desk, ringing his bell, knocking at the gates of science.
It is not for all men actively to practise a science and advance it. But its gifts are gratuitous, and there is no one who need go in want of them, nor anyone, I think, who may scorn them wholly and call himself a modern. For it speaks the universal language, and prevails upon the mysteries by friendship. It is the taste of dragon’s blood upon the lips that makes us understand the speech of birds. Where it turns its gaze, it puts a new dimension in the scene, deepening it with marvelous perspectives. And though so marvelous, they are real — more real than the evidence of the unaided senses. So science sees into the heart of the oak.
This science, this cool way of looking, this thorough journey round a little space and daring project into vast spaces, carried away a mind that had been encouraged so far chiefly to intuitional judgments and emotional understanding. It was all too easy to have opinions on books, music, architecture. But appreciation is an edge that dulls with repetition; emotion is inconstant. Science has no use for any of this; it required instead a bracing impersonality. Under the spell of the new vision, three student years rushed by, and night after night it would be six-thirty when they had to put me out of the Gray Herbarium.
At Harvard the big men in the science faculty are found in the elementary courses. However imperfectly I understood them, they were giving me of the very best that pure science could offer. It was foreseeable that the details of all these courses might be forgotten. It was common knowledge that our teachers did not agree among themselves. But they had one spirit in common and they saw the same vision. That was what you were there to see, through them.
They brought discipline to cap the spouting of youthful convictions. They taught us to postpone judgments, to acknowledge mistakes, to mistrust your own work and give cordial credit to others’, to assume nothing general from particular instance, to search for contrary evidence as if it were pearls, to walk all around a question, to define a problem, to finish what you began. These are some of their Commandments, and if we did not keep them any better than God’s, mercy shown to the ignorant could no longer be ours.
The chemistry and zoology and philosophy students gave me, practically, the gist of the advanced courses a botanist could not crowd in. Youngsters who knew a really remarkable lot about insects, genetics, and ancient life on earth shared it in the same rich gossip. So I became secretly persuaded that the value of a speciality was to learn it not in a specialized way but connectively, excursively, in its relation to the allness of things.
In the botanical faculty, at least, there was little hint that all these courses in the chemistry of plant life, structure of woods, the geography of plant distribution, and the evolution of the fungi, had application. A thorough grounding in theory is of course a splendid background for subsequent application, but my titans did not consider themselves in the background of anything. Except for one splendid course in the plant diseases, I never heard mention of any economic aspect of my subject. Pure science was never purer; such a training fitted one perfectly to teach it to future teachers.
Shaking off the confetti of graduation, alone of my fellow students (who all went on to three years of postgraduate work and subsequent triumphs) I went out into the world that makes use of things — myself of no very great use to anybody. After the finals I had survived, the civil-service examination seemed deplorably easy. Then I was introduced to my superiors, men cordial, forbearing, helpful.
Novice in something like a religious faith that the flora of North America was the only proper subject of study for North Americans, I went to work under a veteran plantsman who had circled the globe many times in search of beautiful or significant exotics. I learned that there were twenty-seven thousand species of plants in cultivation in my own country, which was more than twice the number of native flowering plants. Thoroughly informed concerning sedges, which are notable for their uselessness, I found myself among men to whom it was inconceivable that one should be so ignorant of the grasses, the most important family that grows upon the earth. Some talked in terms of the range grasses of the great western grazing country, others of winter wheats and spring wheats, hard and soft wheats, spelt and durum, sorghum and broom corn. I was set to work on a survey of the tanninbearing plants of the world, and I learned for the first time of the great quebracho forests of Argentina, dwindling under the assaults of a tanninhungry world. I heard of tung oil, in which China held a monopoly until our office set out a valiant plantation in Florida, to supply airplanes with lubricant. The Department was breaking the Japanese grip upon camphor, which is a sinew of war and the body of the flickering film. Dates of Oman for the Imperial Valley, upland rice for the Sacramento Valley, chaulmoogra trees in the uncertain hope of victory over leprosy — these were all Department projects, triumphs ringing fresh when I came into the Office. My horizons seemed suddenly to have leaped away, leaving the world wider, a thousand times more various, infinitely more purposeful and solid than ever I had guessed it might be.
The Office of Foreign Seed and Plant Introduction was then the most colorful service in the Department. It had been the cradle of the great corps of agricultural explorers who were ransacking the ultimate corners of the earth for new crops or better varieties of old ones. As a packet of rattling, clicking, potent seeds these came to Washington to be set out in experimental stations, propagated, distributed to private collaborators and, at the last, released, if found worthy, to commerce. Or they entered the country as cuttings — a little tied bundle of sticks like the fasces that Romans used to send the people on whom they intended to make war; but this was a war to break, perhaps, the monopoly of some foreign land in camphor or quinine or kapok or fruits. Or the rooted seedlings came, sheltered like traveling babies, in Wardian cases that had crossed the equator to get to us.
And with plants arrived the explorers’ letters. They came from Cathay and Samarkand, the Andes and Sokotra, isle of frankincense, aloes, and myrrh. They brought stories of fatigue, frustration, loneliness, and disasters. One explorer had been drowned in the Yangtze, a man perhaps already so drowned in China that when he slipped over the side of the steamer he no longer knew what he did. That man was Frank N. Meyer, Hollander, American, China-man. I thought of him when I opened the letter from the ranch woman in eastern Montana, when I was handling the annual distribution of our plant material. It read:
We got no trees hear. They all blowed down or dide. For God’s sake send us shade.
I sent her Meyer’s Mongolian elm. It withstands drought, flood, alkali, insects, fungus diseases, searing heat, and killing cold.
Lingering sometimes in the dark of the tall file cases, I overheard the councils of the bigwigs, their voices rumbling just beneath the monotonous roar of the electric fans that flail at Washington’s perpetual muggy heat without ever dispelling it. Talking, in there, might be the old specialist who battled with the cancers of plants, or an authority from Crop Estimates, where they cast up the bread account of the world and foretell who shall starve, who fatten. In the anterooms of the Cotton Rating office I met the representatives of the British Empire wherever it can raise cotton, or Frenchmen talking for Africa. When I went on an errand to Forest Service, I always thought I smelled around the place the raw odor of living timber, cut, or the exciting, frightening scent of smoke. For Forest Service is not concerned alone with conserving fine trees or polishing up cross-cut specimens; its business, I learned, was that of a tremendous fire brigade, and quite as much with the cropping of national timber resources.
Of such was the spell of the Department; no need here to mention its grind. It too had limitations; it had its politics and its crush for preferment; it was bound in its own conventions and unquestionably hobbled in red tape.
But now at any rate I had traveled about a little in two provinces of the plant kingdom. Theory and application were both living realities to me, and either might have offered a practising scientist field for a lifework. If proficient enough, a man could settle down with some comfort into the routine of economic botany, in the thought that he was at all events of practical use.
After these patterns I was not cut. I left the Department for travel of my own mapping.
In some cases the travel was literal, as when I got up into my first alpine pass and saw the whole flowering meadow close its blossoms at a darkening sky. Again it might be a long stay, like those months in a field laboratory under coco palms; there I listened through a microphone to the unearthly, painfully high song of an electric current as it passed through the saps of tropical trees, by pitch denoting the concentration of their hydrogen ions, and their consequent resistance to frost.
There were summers afield in the dunes, studying less the restless, hissing hills of sand that devour forests alive than reedy lakes behind them where eelgrass and starwort drifted at the surface of the dark water, and wild rice rose to hang out the husky invitation of grass flowers. And I went trotting the bogs after grass-of-Parnassus shaking on hairfine stems, and pipewort on its pipestems ending in a tight head of grey blossoms — perhaps the strangest stray out of another time and world in all our flora.
But best were long residences. In the flower basket of Provence narcissus grows wild and native, hyacinths dance under the olives, and squills and primroses push beneath the ilex oaks. This is the floral province from which our spring garden has come; it is the same flora that you find in Homer and the Latin bucolics; Linnaeus gave it half its scientific names and Darwin studied these same oxlips and bee orchis.
Here a New World naturalist feels that he walks classic ground. But he can add nothing to it; it belongs to Europeans; so he goes back to his own, which is legendless, and vaster.
That was how I came to live for years in an American grove of burr oaks under whose high, elderly, indulgent boughs the little wild plum and crab and the flat-topped hawthorns fume with blossoms that become hard, bright, tangy, and astringent fruits. Seeing one problem, one square mile of land, as a Chinese landscape painter is said to look at one scene for three years until he could paint it in his sleep, I grew aware of greater implications behind the surface of this candid Nature. My newly wakening interest was ecology — loosely defined as the sociology of plants. It describes the aspect and composition of plant communities, and how the environment exerts on them its power. Look deeper, and there remains to be understood the response within the plant itself that springs from its own nature.
For it was Nature in its deepest sense that, I saw, was the business for me. Precisely because in the green kingdom the law of instinct is not known, the writ of intelligence does not run, plants clearly and unprejudiced tell biologic truth. By that token all flowers are glass flowers (and the coiled fern and the twisted algal tress too), and looking into them the rapt observer sees great first principles composed together there serene as lights in a gem.
What we love, when on a summer day we step into the coolness of a wood, is that its boughs close up behind us. We are escaped, into another room of life. The wood does not live as we live, restless and running, panting after flesh, and even in sleep tossing with fears. It is aloof from thoughts and instincts; it responds, but only to the sun and wind, the rock and the stream — never, though you shout yourself hoarse, to propaganda, temptation, reproach, or promises. You cannot mount a rock and preach to a tree how it shall attain the kingdom of heaven. It is already closer to it, up there, than you will grow to be. And you cannot make it see the light, since in the tree’s sense you are blind. You have nothing to bring it, for all the forest is self-sufficient; if you burn it, cut, hack through it with a blade, it angrily repairs the swathe with thorns and weeds and fierce suckers. Later there are good green leaves again, toiling, adjusting, breathing — forgetting you.
For this green living is the world’s primal industry; yet it makes no roar. Waving its banners, it marches across the earth and the ages, without dust around its columns. I do not hold that all of that life is pretty; it is not, in purpose, sprung for us, and moves under no compulsion to please. If ever you fought with thistles, or tried to uproot a cattail’s matted rootstocks, you will know how plants cling to their own lives and defy you. The pond scums gather in the cistern, frothing and buoyed with their own gases; the storm waves fling at your feet upon the beach the limp sea-lettuce wrenched from its submarine hold —reminder that there too, where the light is filtered and refracted, there is life still to intercept and net and by it proliferate. Inland from the shore I look and see the coastal ranges clothed in chaparral — dense shrubbery and scrubbery, closefisted, intricately branched, suffocating the rash rambler in the noon heat with its pungency. Beyond, on the deserts, under a fierce sky, between the harsh lunar ranges of unweathered rock, life still, somehow, fights its way through the year, with thorn and succulent cell and indomitable root.
Between such embattled life and the Forest of Arden, with its ancient beeches and enchanter’s nightshade, there is no great biologic difference. Each lives by the cool and cleanly and most commendable virtue of being green. And though that is not biological language, it is the whole story in two words. So that we ought not speak of getting at the root of a matter, but of going back to the leaf of things. The orator who knows the way to the country’s salvation and does not know that the breath of life he draws was blown into his nostrils by green leaves had better spare his breath. And before anyone builds a new state upon the industrial proletariat, he will be wisely cautioned to discover that the source of all wealth is the peasantry of grass.
And the reason for these assertions — which I do not make for metaphorical effect but maintain quite literally — is that the green leaf pigment, called chlorophyll is the one link between the sun and life; it is the conduit of perpetual energy to our own frail organisms.
For inert and inorganic elements — water and carbon dioxide of the air, the same that we breathe out as a waste — chlorophyll can synthesize with the energy of sunlight. Every day, every hour of all the ages, as each continent and, equally important, each ocean rolls into sunlight, chlorophyll ceaselessly creates. Not figuratively, but literally, in the grand First Chapter Genesis style. One instant there are a gas and a water, as lifeless as the core of earth or the chill of space; and the next they are become living tissue — mortal yet genitive, progenitive, resilient with all the dewy adaptability of flesh, ever changing in order to stabilize some unchanging ideal of form. Life, in short, synthesized, plantsynthesized, light-synthesized. Botanists say photosynthesized. So that the postBiblical synthesis of life is already a fact. Only when man has done as much may he call himself the equal of a weed.
Plant life sustains the living world; more precisely, chlorophyll does so, and where, in the vegetable kingdom, there is not chlorophyll or something closely like it, then that plant or cell is a parasite — no better, in vital economy, than a mere animal or man. Blood, bone, and sinew, all flesh is grass. Grass to mutton, mutton to wool, wool to the coat on my back — it runs like one of those cumulative nursery rhymes, the wealth and diversity of our material life accumulating from the primal fact of chlorophyll’s activity. The roof of my house, the snapping logs upon the hearth, the desk where I write, are my imports from the plant kingdom. But the whole of modern civilization is based upon a whirlwind spending of the plant wealth long ago and very slowly accumulated. For fundamentally, and away back, coal and oil, gasoline and illuminating gas, had green origins too. With the exception of a small amount of water power, a still smaller of wind and tidal mills, the vast machinery of our complex living is driven only by these stores of plant energy.
We, then, the animals, consume those stores in our restless living. Serenely the plants amass them. They turn light’s active energy to food, which is potential energy stored for their own benefit. Only if the daisy is browsed by the cow, the maple leaf sucked of its juices by an insect, will that green leaf become of our kind. So we get the song of a bird at dawn, the speed in the hoofs of the fleeing deer, the noble thought in the philosopher’s mind. So Plato’s Republic was builded on leeks and cabbages.
Animal life lives always in the red; the favorable balance is written on the other side of life’s page, and it is written in chlorophyll. All else obeys the thermodynamic law that energy forever runs downhill, is lost and degraded. In economic language, this is the law of diminishing returns, and it is obeyed by the cooling stars as by man and all the animals. They float down its Lethe stream. Only chlorophyll fights up against the current. It is the stuff in life that rebels at death, that has never surrendered to entropy, final icy stagnation. It is the mere cobweb on which we are all suspended over the abyss.
And what then is this substance which is not itself alive but is made by life and makes life, and is never found apart from life?
I remember the first time I ever held it, in the historic dimness of the old Agassiz laboratories, pure, in my hands. My teacher was an owl-eyed master, with a chuckling sense of humor, who had been trained in the greatest laboratory in Germany, and he believed in doing the great things first. So on the first day of his course he set us to extracting chlorophyll, and I remember that his eyes blinked amusement behind his glasses, because when he told us all to go and collect green leaves and most walked all the way to the Yard for grass, I opened the window and stole from a vine upon the wall a handful of Harvard’s sacred ivy.
We worked in pairs, and my fellow student was a great-grandnephew, or something of the sort, of Elias Fries, the founder of the study of fungi. Together we boiled the ivy leaves, then thrust them in alcohol. After a while it was the leaves which were colorless while the alcohol had become green. We had to dilute this extract with water, and then we added benzol, because this will take the chlorophyll away from the alcohol which, for its part, very conveniently retains the yellow pigments also found in leaves. This left us with a now yellowish alcohol and, floating on top of it, a thick green benzol; you could simply decant the latter carefully off into a test tube, and there you had chlorophyll extract, opaque, trembling, heavy, a little viscous and oily, and smelling, but much too rankly, like a lawn-mower’s blades after a battle with rainy grass.
Then, in a darkened room where beams from a spectroscope escaped in painful darts of light as from the cracks in an old-fashioned magic lantern, we peered at our extracted chlorophyll through prisms. Just as in a crystal chandelier the sunlight is shattered to a rainbow, so in the spectroscope light is spread out in colored bands — a long narrow ribbon, sorting the white light by wave lengths into its elemental parts. And the width, the presence or the absence, of each cross-band on the ribbon tells the tale of a chemical element present in the spectrum, much as the bands on a soldier’s insignial ribbon show service in Asia, in the tropics, on the border, in what wars. When the astronomer has fixed spectroscope instead of telescope upon a distant star, he reads off the color bands as easily as one soldier reads another’s, and will tell you whether sodium or oxygen, helium or iron, is present.
Just so our chlorophyll revealed its secrets. The violet and blue end of the spectrum was almost completely blacked out. And that meant that chlorophyll absorbed and used these high-frequency waves. So, too, the red and orange were largely obliterated, over at the righthand side of our telltale bar. It was the green that came through clearly. So we call plants green because they use that color least. It is what they reject as fast as it smites the upper cells; it is what they turn back, reflect, flash into our grateful retinas.
It was only routine in a young botanist’s training to make an extraction and spectrum analysis of chlorophyll. My student friends over in the chemistry laboratories were more excited than I about it. They were working under Conant, before he became president of Harvard and had to sneak into his old laboratory at night with a key he still keeps. For chlorophyll was Conant’s own problem. His diagram of its structure, displayed to me by his students, was closely worked over with symbols and signs, unfolded to something like the dimensions of a blueprint of Boulder Dam, and made clear — to anyone who could understand it! — how the atoms are arranged and deployed and linked in such a tremendous molecule as MgN4C55H72O3.
To Otto and Alfred and Mort every jot and joint in the vast Rube Goldberg machinery of that structural formula had meaning, and more than meaning — the geometrical beauty of the one right, inevitable position for every atom. To me, a botanist’s apprentice, a future naturalist, there was just one fact to quicken the pulse. That fact is the close similarity between chlorophyll and hemoglobin, the essence of our blood.
So that you may lay your hand upon the smooth flank of a beech and say, ‘We be of one blood, brother, thou and I.’
The one significant difference in the two structural formulas is this: that the hub of every hemoglobin molecule is one atom of iron, while in chlorophyll it is one atom of magnesium.
Iron is strong and heavy, clamorous when struck, avid of oxygen and capable of corruption. It does not surprise us by its presence in our blood stream. Magnesium is a light, silvery, unresonant metal; its density is only one seventh that of iron, it has half of iron’s molecular weight, and melts at half the temperature. It is rustless, ductile, and pliant; it burns with a brilliant white light rich in actinic rays, and is widely distributed through the upper soil, but only, save at mineral springs, in dainty quantities. Yet the plant succeeds always in finding that mere trace that it needs, even when a chemist might fail to detect it.
How does the chlorophyll, green old alchemist that it is, transmute the dross of earth into living tissue? Its hand is swifter than the chemist’s most sensitive analyses. In theory, the step from water and carbon dioxide to the formation of sugar (the first result readily discerned) must involve several syntheses; yet it goes on in a split hundredth of a second. One sunlight particle or photon strikes the chlorophyll, and instantaneously the terribly tenacious molecule of water, which we break down into its units of hydrogen and oxygen only with difficulty and expense, is torn apart; so too is the carbon dioxide molecule. Building blocks of the three elements, carbon, hydrogen, and oxygen, are then whipped at lightning speed into carbonic acid; this is instantly changed over into formic acid — the same that smarts so in our nerve endings when an ant stings us. No sooner formed than formic acid becomes formaldehyde and hydrogen peroxide. This last is poisonous, but a ready enzyme in the plant probably splits it as fast as it is born into harmless water and oxygen, while the formaldehyde is knocked at top speed into a new pattern — and is grape sugar, glucose. And all before you can say Albert Einstein. Indeed, by the time you have said Theophrastus Bombastus Aureolus Paracelsus von Hohenheim, the sugar may have lost a modicum of water — and turned into starch, the first product of photosynthesis that could be detected by the methods of fifty years ago.
At this very instant, with the sun delivering to its child the earth, in the bludgeoning language of mathematics, 215 X 1015 calories per second, photosynthesis is racing along wherever the leaf can reach the light. (All else goes to waste.) True, its efficiency is very low — averaging no better than 1 per cent, while our machines are delivering up to 25 per cent of the fuel they combust. But that which they burn — coal and gas, oils and wood — was made, once, by leaves in ancient geologic times. The store of such energy is strictly finite. Chlorophyll alone is hitched to what is, for earthly purposes, the infinite.
Light, in the latest theory, is not waves in a sea of ether, or a jet from a nozzle; it could be compared rather to machine-gun fire, every photoelectric bullet of energy traveling in regular rhythm, at a speed that bridges the astronomical gap in eight minutes. As each bullet hits an electron of chlorophyll it sets it to vibrating, at its own rate, just as one tuning fork, when struck, will cause another to hum in the same pitch. A bullet strikes— and one electron is knocked galley-west into a dervish dance like the madness of the atoms in the sun. The energy splits open chlorophyll molecules, recombines their atoms, and lies there, dormant, in foods.
The process seems miraculously adjusted. And yet, like most living processes, it is not perfect. The reaction time of chlorophyll is not geared as high as the arrival of the light-bullets. Light comes too fast; plants, which are the very children of light, can get too much of it. Exposure to the sunlight on the Mojave Desert is something that not a plant in my garden, no, nor even the wiry brush in the chaparral, could endure. Lids against the light plants do not have; but by torsions of the stalk some leaves may turn their blades edgeon to dazzling radiation, and present them again broadside in failing light. Within others the chlorophyll granules too, bun or pellet-shaped as they are, can roll for a side or frontal exposure toward the light. In others they can crowd to the top of a cell and catch faint rays, or sink or flee to the sides to escape a searing blast.
In their requirements, their tolerances, their blindnesses, leaves are much like our human eyes. As we cannot behold the infra-red rays, and call them darkness, so the plant does not avail itself of them; it is not too much to say that it is blind to them. Ultra-violet rays are dangerous to us; they may impart deep burns. The leaf too can neither use these high vibrations nor much endure them. Photosynthesis proceeds best at very nearly the temperatures we find supportable. Leaves must have drink, as we must; they must breathe oxygen, as we breathe it. They have tender youth, and strong maturity, fragile age, and death — a skeleton in the ground, that at last is mould.
When I began to write these pages, before breakfast, the little fig tree outside my window was rejoicing in the early morning fight. It is a special familiar of my work, a young tree that has never yet borne fruit. It is but a little taller than I, has only two main branches and forty-three twigs, and the brave if not impressive sum of two hundred and sixteen leaves — I have touched every one with a counting finger. Though sparse, they are large, mitten-shaped, richly green with chlorophyll. I compute, by measuring the leaf and counting both sides, that my little tree has a leaf surface of about eighty-four square feet. This sun-trap was at work to-day long before I.
Those uplifted hand-like leaves caught the first sky light. It was poor for the fig’s purpose, but plant work begins from a nocturnal zero. When I came to my desk the sun was full upon those leaves — and it is a wondrous thing how they are disposed so that they do not shade each other. By the blazing California noon, labor in the leaves must have faltered from very excess of light; all the still golden afternoon it went on; now as the sun sets behind a sea fog the little fig slackens peacefully at its task.
Yet in the course of a day it has made sugars for immediate burning and energy release, put by a store of starch for future use; with the addition of nitrogen and other salts brought up in water from the roots it has built proteins too — the very bricks and mortar of the living protoplasm, and the perdurable stuff of permanent tissue. The annual growth ring in the wood of stem and twigs has widened an infinitesimal but a real degree. The fig is one day nearer to its coming of age, to flowering and fruiting. Then, still leafing out each spring, still toiling in the sunlight that I shall not be here to see, it may go on a century and more, growing eccentric, solidifying whimsies, becoming a friend to generations. It will be ‘the old fig’ then. And at last it may give up the very exertion of bearing. It will lean tough elbows in the garden walks, and gardeners yet unborn will scold it and put up with it. But still it will leaf out till it dies.
Dusk is here now. So I switch on the lamp beside my desk. The powerhouse burns its thousand tons of coal a week, and gives us this instant and most marvelous current. But that light is not new. It was hurled out of the sun, two hundred million years ago, and was captured by the leaves of the Carboniferous fern-tree forests, fell with the falling plant, was buried, fossilized, dug up, and resurrected. It is the same light. And, in my little fig tree as in the ancient ferns, it is the same unchanging green stuff from age to age, passed without perceptible improvement from evolving plant to plant. What it is and does, so complex upon examination, lies about us tranquil and simple, with the simplicity of a miracle.
(A second installment of ’The Flowering Seed ’will appear in the October issue)