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In the Likeness of God Copyright
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I have been trying to think of the earth as a kind of organism, but it is no go. I cannot think of it this way. . . . The other night, driving through a hilly, wooded part of southern New England, I wondered about this. If not like an organism, what is it like, what is it most like? Then, satisfactorily for that moment, it came to me: it is most like a single cell. Lewis Thomas
I remember the first time I saw a living cell under a microscope. I was twenty-one years old and taking a short course in tropical hygiene at Livingstone College in England. We had been studying parasites, but our specimens were dead; I wanted to see a living amoeba. Early one morning, before the laboratory was cluttered with students, I sneaked into the old science building. The imposing red brick structure stood next to a pond from which I had just scooped some water in a teacup. Bits of decomposing leaves floated in the turbid water, smelling of decay and death.
But when I touched one drop of that water to a microscope slide, a universe sprang to life. Hundreds of organisms crowded into view: delicate, single-celled globes of crystal, breathing, unfurling, flitting sideways, excited by the warmth of my microscope light. I edged the slide a bit, glancing past the faster organisms. Ah, there it was. An amoeba. A mere chip of translucent blue, it was barely visible to my naked eye, but the microscope revealed even its inner workings.
Something about the amoeba murmurs that it is one of the most basic and primordial of all creatures. Somehow it has enlisted the everyday forces of millions of spinning atoms so that they now serve life, which differs profoundly from mere matter. Just an oozing bit of gel, the amoeba performs all the basic functions that my body does. It breathes, digests, excretes, reproduces. In its own peculiar way it even moves, plumping a hummock of itself forward and following with a motion as effortless as a drop of oil spreading on a table. After one or two hours of such activity, the grainy, watery blob will have traveled a third of an inch.
That busy, throbbing drop gave me my first graphic image of the jungle of life and death we share. I saw the amoeba as an autonomous unit with a fierce urge to live and a stronger urge to propagate itself. It beckoned me on to explore the living cell.
Years later I am still observing cells, but as a physician I focus on how they cooperate within the body.
Now I have my own laboratory, at a leprosy hospital on swampy ground by the Mississippi River in Carville, Louisiana. Again I enter the lab early before anyone is stirring, this time on a chilly winter morning. Only the soft buzz of fluorescent lights overhead breaks the quietness.
But I have not come to study amoebae. This morning I will examine a hibernating albino bat who sleeps in a box in my refrigerator. I rely on him to study how the body responds to injury and infection. I lift him carefully, lay him on his back, and spread his wings in a cruciform posture. His face is weirdly human, like the shrunken heads in museums. I keep expecting him to open an eye and shriek at me, but he doesn't. He sleeps.
As I place his wing under the microscope lens, again a new universe unfolds. I have found a keyhole. The albinic skin under his wing is so pale that I can see directly through his skin cells into the pulsing capillaries which carry his blood. I focus the microscope on one bluish capillary until I can see individual blood cells pushing, blocking, thrusting through it. Red blood cells are by far the most numerous: smooth, shiny discs with centers indented like jelly doughnuts. Uniform size and shape make them seem machinestamped and impersonal.
More interesting are the white blood cells, the armed forces of the body which guard against invaders. They look exactly like the amoebae: amorphous blobs of turgid liquid with darkened nuclei, they roam through the bat's body by extending a finger-like projection and humping along to follow it. Sometimes they creep along the walls of the veins; sometimes they let go and free-float in the bloodstream. To navigate the smaller capillaries, bulky white cells must elongate their shapes, while impatient red blood cells jostle in line behind them.
Watching the white cells, one can't help thinking them sluggish and ineffective at patrolling territory, much less repelling an attack. Until the attack occurs, that is. I take a steel needle and, without waking the bat, prick through its wing, puncturing a fine capillary. An alarm seems to sound. Muscle cells contract around the damaged capillary wall, damming up the loss of precious blood. Clotting agents halt the flow at the skin's surface. Before long, scavenger cells appear to clean up debris, and fibroblasts, the body's reweaving cells, gather around the injury site. But the most dramatic change involves the listless white cells. As if they have a sense of smell (we still don't know how they 'sense' danger), nearby white cells abruptly halt their aimless wandering. Like beagles on the scent of a rabbit, they home in from all directions to the point of attack. Using their unique shape-changing qualities, they ooze between overlapping cells of capillary walls and hurry through tissue via the most direct route. When they arrive, the battle begins.
Lennart Nilsson, the Swedish photographer famous for his remarkable closeups of activity inside the body, has captured the battle on film as seen through an electron microscope. In the distance, a shapeless white cell, resembling science fiction's creature 'The Blob,' lumbers toward a cluster of luminous green bacterial spheres. Like a blanket pulled over a corpse, the cell assumes their shape; for awhile they still glow eerily inside the white cell. But the white cell contains granules of chemical explosives, and as soon as the bacteria are absorbed the granules detonate, destroying the invaders. In thirty seconds to a minute only the bloated white cell remains. Often its task is a kamikaze one, resulting in the white cell's own death.
In the body's economy, the death of a single white cell is of little consequence. Most only live several days or several weeks, and besides the fifty billion active ones prowling the adult human, a backup force one hundred times as large lies in reserve in the bone marrow. At the cellular level, massive warfare is a daily fact of life. Fifty thousand invaders may lurk on the rim of a drinking glass, and a billion can be found in a half-teaspoon of saliva. Bacteria enshroud my body---every time I wash my hands I sluice five million of them from the folds of my skin.
To combat these threats, some of the blood's white cells are specifically targeted to one type of invader. If the body has experienced contact with a severe danger, as in a smallpox vaccination, it imprints certain white cells with a death-wish to combat that single danger. These cells spend their lives coursing through the bloodstream, waiting, scouting. Often they are never called upon to give battle. But if they are, they hold within them the power to disarm a foreign agent that could cause the destruction of every cell in the body.