92
The Body Electric
smells of the biochemistry lab or the dissecting room's preserved organs.
I had another worthy ally when I started to reevaluate the role of
electricity in life. Albert Szent-Gyorgyi, who'd already won a Nobel
Prize for his work on oxidation and vitamin C, made a stunning sugges-
tion in a speech before the Budapest Academy of Science on March 21,
1941. (Think of the date. World War II was literally exploding around
him, and there he was, calmly laying the foundations for a new biology.)
Speaking of the mechanistic approach of biochemistry, he pointed out
that when experimenters broke living things down into their constituent
parts, somewhere along the line life slipped through their fingers and
they found themselves working with dead matter. He said, "It looks as
if some basic fact about life were still missing, without which any real
understanding is impossible." For the missing basic fact, Szent-Gyorgyi
proposed putting electricity back into living things, but not in the way
it had been thought of at the turn of the century.
At that earlier time, there had been only two known modes of current
conduction, ionic and metallic. Metallic conduction can be visualized as
a cloud of electrons moving along the surface of metal, usually a wire. It
can be automatically excluded from living creatures because no one has
ever found any wires in them. Ionic current is conducted in solutions by
the movement of ions—atoms or molecules charged by having more or
fewer than the number of electrons needed to balance their protons'
positive charges. Since ions are much bigger than electrons, they move
more laboriously through the conducting medium, and ionic currents
die out after short distances. They work fine across the thin membrane of
the nerve fiber, but it would be impossible to sustain an ionic current
down the length of even the shortest nerve.
Semiconduction, the third kind of current, was a laboratory curiosity
in the 1930s. Halfway between conductors and insulators, the semicon-
ductors are inefficient, in the sense that they can carry only small cur-
rents, but they can conduct their currents readily over long distances.
Without them, modern computers, satellites, and all the rest of our
solid-state electronics would be impossible.
Semiconduction occurs only in materials having an orderly molecular
structure, such as crystals, in which electrons can move easily from the
electron cloud around one atomic nucleus to the cloud around another.
The atoms in a crystal are arranged in neat geometrieal lattices, rather
than the frozen jumble of ordinary solids. Some crystalline materials
have spaces in the lattice where other atoms can fit. The atoms of these
impurities may
have more or fewer electrons than the atoms of the lat-
tice material. Since the forces of the latticework structure hold the same