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
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 machine-stamped
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.
* * *
Often I have reflected on the paradox of the amoeba and its
mirror image, the white cell. The amoeba, a self-contained organism,
alone performs all the basic functions of life, depending on
other cells only when it ingests them as food. The white cell,
though similar in construction and makeup, in a sense is far less
free. A larger organism determines its duties, and it must sometimes
sacrifice its life for the sake of that organism. Although more
limited in self-expression, the white cell performs a singularly vital
function. The amoeba flees danger; the white cell moves toward it.
A white cell can keep alive a person like Beethoven or Newton or
Einstein . or you and me.
I sometimes think of the human body as a community, and then
of its individual cells such as the white cell. The cell is the basic unit
of an organism; it can live for itself, or it can help form and sustain
the larger organism. I recall the apostle Paul's use of analogy in
1 Corinthians 12 where he compares the church of Christ to the
human body. That inspired analogy takes on even more meaning to
me because of the expanded vistas allowed by the invention of
microscopes. Since Paul's analogy renders a basic principle of God's
creation, I can augment it like this:
The body is one unit, though it is made up of many cells, and
though all its cells are many, they form one body If the
white cell should say, because I am not a brain cell, I do not
belong to the body, it would not for that reason cease to be
part of the body. And if the muscle cell should say to the optic
nerve cell, because I am not an optic nerve, I do not belong to
the body, it would not for that reason cease to be part of the
body. If the whole body were an optic nerve cell, where would
be the ability to walk? If the whole body were an auditory
nerve, where would be the sense of sight? But in fact God has
arranged the cells in the body, every one of them, just as he
wanted them to be. If all cells were the same, where would the
body be? As it is, there are many cells, but one body.
That analogy conveys a more precise meaning to me because
though a hand or foot or ear cannot have a life separate from the
body, a cell does have that potential. It can be part of the body as
a loyalist, or it can cling to its own life. Some cells do choose to live
in the body, sharing its benefits while maintaining complete independence
-they become parasites or cancer cells.