by Guy Murchie
If dissemination distributes seeds in space, however, it is germination that distributes them in time, a dimension no less critical to a seed seeking a season suited to its survival. Germination naturally requires moisture, free oxygen and moderate warmth, but it would be much too simple, in fact suicidal, if all seeds could germinate at the first warm sprinkle of rain, for desert plants would often sprout into a deadly drought only momentarily relieved by those few drops, or an apple shoot would respond to a December thaw barely in time to be cut dead by a January freeze. So a great many seeds are provided with special insulated or time-locked coats to inhibit germination until the optimum moment. The waterproof "varnish" on a cherry seed remains undissolvable until ground by a gizzard and corroded by digestive acids and bacteria, ensuring that if the seed attains optimum sowing (by a bird) it will not only be alive but cocked for triggering by the next rain. Many such seeds are adapted to the digestions of particular animals, such as quandong seeds in Australia, which, after the prunelike fruit is eaten by an emu, germinate in his droppings; and the seedpod of the camel thorn in Africa, favored by the elephant, from whose dung the seeds are commandeered by dung beetles to be buried in seed beds specialized for rapid sprouting.
Apple seeds stubbornly resist germination until several months of cold have convinced them that the succeeding warmth must really be spring. Certain orchid seeds also hold off until a friendly "infection" of mold has eaten away their raincoats, while a few larger seeds, curiously, have evolved what amounts to a yearning for burning, notably jack pine, whose scorched cones opportunistically snap open during a forest fire to reseed the ground when it is bare of competition.
A great many seeds, it has recently been discovered, are extraordinarily sensitive to light (particularly red light), some (like mistletoe) germinating only by day and others (such as onion) only in the dark, though always other factors complicate the outcome. Some seeds also contain remarkably accurate natural "clocks" as proved by their inherited 24-hour rhythms and their surprising sensitivity to precise lengths of days and nights that not only trigger germination but the opening of buds and blossoms later on. Although long periods of dormancy tend to make a seed less viable, they also often make it more germinable, a distinctly different thing. The record for unfrozen dormancy is now held by two ancient lotus seeds found in a peat bog in Japan in 1951. Affirmed by carbon-14 dating to be 2000 years old, the seeds were cut open, put in tepid water and sprouted four days later, soon blossoming into beautiful pink flowers, just as they would have if they had been allowed to germinate before the birth of Christ.
If they are frozen, however, seeds will retain their viability almost indefinitely, like the arctic tundra lupine seeds found in 1954 after 10,000 years of lying deep in frozen silt in the upper Yukon valley and which, when planted on wet filter paper in 1967, germinated within 48 hours to produce normal healthy flowers. Certain kinds of seeds, on the other hand, will not germinate before a set date no matter what you do to hurry them. Even boiling them for hours does not disturb their slumber, for evidently their "clocks" have not struck the appointed hour. It seems that a sort of digestion process goes on in acorns and other seeds, slowly converting fats into carbohydrates, which may be what works their "clocks."
When "G-day" finally arrives and germination is triggered, the first noticeable change in the seed is that its shell has become permeable and it drinks water, its crystals unlock and it swells up somewhat, as an animal will stretch itself after a long sleep. Thus wheat and corn kernels absorb about half their weight in water and the garden pea drinks its full weight. Next the increased pressure of the swollen seed bursts the shell open, perhaps at prepared seams (as in the walnut) or "doors" (as in the coconut), while the released embryo, inhaling oxygen like an inward yawn, starts dividing its cells in rapid growth, usually sprouting first a root downward, then a shoot upward, like a baby hunting for a nipple (corresponding to earth) before he opens his eyes (corresponding to leaves).
The buds that form on a tree every winter are worth mentioning here too because, like seeds, they are a strikingly successful means of carrying on life from one season to the next. As soon as dead leaves drop off in autumn, their stems parting at a "tear off" line plainly perforated for the purpose, new buds start forming at that line in preparation for next year's greenth. And, like a seed, each bud is an embryo organism, perhaps an unborn limb, with its own tiny stem, leaves or petals and a stock of sugary food neatly folded in the little waterproof shell that protects it, not so much from the cold (which keeps it asleep) as from drought at a season when the tree's water system may be too icebound to replenish any evaporated liquid.
Every tree and plant, it is found, has its own special budding inducements: a warm day for the pea, a warm night for the tomato, a particular day-night ratio for the cocklebur, a holding thaw after prolonged cold for the lily, a combination of warmth and long daylight for the strawberry. And most of them are ineffably complex and mysterious.
Also, like seeds, the leaves when they appear develop their own distinctive shapes and "purposes," in peas some becoming tendrils for climbing, in the barberry some turning into thorns for defense, others producing hard-to-fathom aerodynamic effects. And of course whole trees take on their characteristic shapes too: the vaselike, widecrowned American elm, the oblate spreading oak, the tapering fir, the graceful tresses of willow, the tall quill of poplar, the candle flame of cypress, the feather duster of palm...
One of the collective functions of plants that impresses me strongly is the rarely mentioned but rhythmic, almost peristaltic, swallowing action of their seasonal changes: the sprouting upward of needlelike shoots in spring, the reaching over (sideways) of foliage in summer, the valvelike drop of dead leaves in autumn covering everything on the ground, the burial and decay in winter while awaiting the next upward penetration of spring that will actually pierce and pass the old growth, sewing it securely into the earth. Every year this sequence of stitching and pumping is repeated relentlessly, inexorably, up-overdown-under, up-over-down-under, like a global sewing machine, 1-2-3-4, 1-2-3-4, slibaroom, slibaroom. slibaroom - a heart throbbing in the breast of nature herself - devouring the waste of the world, binding up the shroud of death, digesting the past, winding the clock of life.
It reminds one of man's increasing debt to the older kingdoms and emphasizes the eternal dependence of animals upon vegetables. It raises questions of evolutionary purpose and ultimate planetary potentialities. Does a tree in any sense have a self or a consciousness distinct from the cells inside it, from the forest around it or the earth under it? If men may be looked upon as trees walking, may not trees in turn be animals standing? So far as I can see, we have no reason to suppose consciousness requires nerves or, if it does, that trees are utterly nerveless. And while their feelings may be exemplified by their silent tuning in on radiations from Earth, moon, sun and stars, by their apparently leisurely adaptation to the forest, still they are due some share of our courtesy and consideration. Should they not, like the animals, have their basic rights in a human court of law?
Long ago Walt Whitman asked, "Why are there trees I never walk under but large and melodious thoughts descend upon me?" Somehow the trees' melodies seemed to come to him in sylvan syllables, leading him to hearken to a live oak as a voice singing in the wilderness, perhaps even as a whispered word of God, as when he wrote: "It grew there uttering joyous leaves of dark green."
Descending thence with Walt's melodious thoughts down the weathered trunk to the gentle grass at its feet, let us ponder anew the little things, the earth itself, the stirrings inside all creatures. For what does life finally spring from? Which of us has seen the world of his forefathers of a million years gone by? Who will transpose the conversings of blood with mud, the dainty dialogues in dew? And who can say, when one cherishes a rose, how little or much the rose may cherish in return?
Chapter 3
The World of Little
* * *
THE TOWN OF
DELFT, five miles southeast of that bustling new port called The Hague in Holland, was prosperous but rather quaint in the seventeenth century. Among its thousands of inhabitants there was nothing about the stocky, bright-eyed little draper and alderman named Antony van Leeuwenhoek with his magnifying glass for examining fabrics and his off-hour hobby of grinding lenses to indicate that he was on the verge of a world-changing discovery. Even now it is easy to forget, as we look down on the struggling planet from our perspective of space and time, that Holland was then probably the most progressive country on Earth, an imperial republic leading the planet in naval power, commerce, science, art and letters. Yet among his creative fellow townsmen like Jan Vermeer the painter and Regnier de Graaf the physician, Leeuwenhoek at forty struck no one as much of a pioneer in any branch of knowledge. Not only was he unconnected with Deift's university, he had not even finished elementary school, spoke an ungrammatical Dutch and his only assets were dexterous fingers, excellent eyesight and an extraordinary curiosity abetted by a streak of the proverbial Dutch stubbornness. He had also picked up the rudiments of mathematics, mostly from doing occasional surveying jobs and keeping the books in his drapery shop.
Lens-making in those days was one of the newer do-it-yourself fads introduced by the Renaissance, perhaps comparable to building a homemade telescope today. Although its forgotten history went back at least to the ground and polished magnifying crystals of ancient Nineveh and had entered the realm of commerce upon the invention of eyeglasses in Florence in 1286, its biggest triumph had come only three hundred years later, shortly after the appearance of the telescope (probably in Naples in the 1580s), when Galileo made himself a series of double-lens tubes in 1609 that enabled him to discover the moons of Jupiter, the rings of Saturn and to resolve the stars of the Milky Way. Leeuwenhoek probably did not know about Galileo's subsequent construction of a compound microscope (5 feet long) through which flies looked "like lambs" and walked "on glass while hanging feet upwards."
Leeuwenhoek was content enough just with grinding out hundreds of tiny, single, convex lenses, usually around one eighth of an inch in diameter, which he would shape as fat as beads (for high magnification) and polish with great skill and mount between two plates of brass, copper, silver or, in a few cases, gold (smelted in his own forge) with a little peephole like the aperture of a stopped-down camera. And he usually arranged an adjustable pin on the back side, so that any small object stuck on its point would be exactly in focus. He would thus hold biological specimens like the eye of a gnat, a fly's brain or a spider's spinneret up for inspection against the open sky or, illumined by candles at night, against a dark background for clarity. He did not notice anything very startling at first, but when he magnified droplets of stagnant pond water in the summer of 1674 with lenses that enlarged more than 100 diameters, he was amazed and thrilled to see "very many little animals," as he put it in a letter to the new Royal Society in London, some round, some oval, some with "paws" and tails, darting every which way through this liquid that the world until then had presumed to be just an inert mineral. Later, carefully measuring these microbes in relation to a cheese mite (barely visible to the naked eye), he wrote: "as the size of a small animalcule in the water is to that of a mite, so is a honeybee to a horse, for the distance around one of these little animals is less than the thickness of a mite's hair."
Soon Leeuwenhoek got a phial of seawater and discovered the teeming microscopic life we now call plankton: first, "a little animal that was blackish, having a shape as if `twere made of two globules" and jerking about "after the manner of a very little flea... displaced, at every jump, within the compass of a coarse sand grain." Then some "animalcules which were clear" with "oval figures and snakewise motion," a third kind, "mouse-colored ... very slow" with "stingers" at both ends, and a very tiny variety (presumably protozoans) "that, whenever they lay ... out of the water, would burst and flow... into three or four very small globules ...
In rainwater he discovered a kind that seemed to be composed of from five to eight clear globules loosely clinging together with a long tail ending in another globule. This animal (now identified as a vorticella) fascinated Leeuwenhoek by sticking out "two little horns" (actually eye stalks) which it continuously swiveled around "like a horse's ears," but it also aroused his pity as "the most wretched creature I've ever seen for when, with its tail, it touched any particle it stuck entangled in it, then pulled itself into an oval and did struggle by strongly stretching itself to free its tail, whereupon the whole body snapped together again leaving the tail coiled up serpentwise.
Leeuwenhoek was appalled to behold "hundreds of such animalcules caught fast by one another ... within the span of one coarse grain of sand."
He almost certainly saw thread bacteria as "most exceeding thin little tubes" to the number of "tens of thousands in a single drop of water," swimming slowly "like eels" but "as well backward as forward." And another faster kind that "would oft-times shoot so swiftly forward ... for half a hair's breadth ... that you might think you saw a pike darting through the water..." The smallest lively objects he saw, so minute he could not "assign any figure to `em," were "a thousand times less than the eye of a full-grown louse," but just may have been inert particles activated by the random, thermal bombardment of molecules that was to be described in 1827 by the English botanist Robert Brown (who also assumed the particles alive) and today is commonly called Brownian movement.
Between looking at such oddities as an embryo oyster, a whale's eye, an elephant's tooth, a pig's tongue, a rye germ and a ram sperm, Leeuwenhoek improved the magnifying power of his lenses up to 275 diameters, by which time, one might say, he really had got his teeth into his hobby. I mean by that that this was when he made one of his biggest discoveries by examining a rotten molar from his own mouth, which, he was staggered to realize, was literally crawling. "I can't forbear to tell you, most noble Sirs," he wrote the Royal Society, that "I dug some stuff out of the roots of one of my teeth and in it I found an unbelievably great company of living animalcules, amoving more nimbly than any I had seen up to now. The biggest sort bent their body into curves in going forwards ... I must confess that the whole stuff seemed to me to be alive, with the number of animalcules so extraordinarily great that `twould take a thousand million of some of `em to make up the bulk of a coarse sand grain. Indeed all the people living in our United Netherlands are not as many as the living animals I carry in my own mouth this very day."
Thus did our little draper give the world its first solid evidence of the teeming bacterial life within us, which had been only intuitively suspected by such earlier philosophers as Marcus Terentius Varro of Rome, who in the first century B.C. wrote (perhaps after reading Lucretius on the nature of epidemics and pestiferous atoms) that "near marshy places... live certain minute creatures which cannot be seen by the eyes but out of the air enter the body through the mouth and nose and there cause serious diseases." Leeuwenhoek, moreover, actually examined the air with his lenses, closely scrutinizing innumerable "earthy motes" that he caught floating "commonly in the air" and which must have been "given off by dustsome things. Indeed," he explained, "you can't so much as rub your hands together when they are dry nor stroke your face, without thereby imparting a multitude of tiny scaled-off particles to the air; and `tis even so with wood, earth, smoke... Furthermore," he opined, "I'll not deny that there can be in the air living creatures so small as to escape our sight... Indeed likely they would be begotten in the clouds where, in the continual dampness, they could remain alive and so be conveyed still living to us in mist and rain. I fancy I have seen something of the sort in the early summer of this year 1676 on two occasions when there was a heavy mist here ... and I can well understand that in all falling rain, carried from gutters into water-butts, animalcules are to be found for, along with floating dust, these creatures can be carried in the wind."
It is not only the scope of this unpretentious man's revelations that is remarkable. So is the degree to
which his accuracy has been confirmed in succeeding centuries, for the findings of modern meteorology have established that every cubic centimeter of air within some ten miles of the earth has at least several dozen invisible particles of dust floating in it and, if the air happens to be over a smoggy city, the number can reach into the millions. Many of these tiny nuclei are dry salt granules tossed into the winds as fine ocean spray whose liquid evaporates quickly enough to release a microscopic residue of solid crystal usually encrusted with a little living tissue. Other suspended dust particles are bits of earth raised by friction from such things as shoes, hoofs, wheels, brooms and wind. Some are invisible flakes or spicules from smoke or exhaust fumes. Some are ashes left by vaporized meteorites, billions of which daily stab into the top of the atmosphere from space. And a goodly percentage also are aerial plankton in the form of wafted spores of algae, fungi, bacteria or other plants, grains of pollen, even a few actual seeds and viable fragments of lichen.
