The Body Electric - Micro-ondes

64 The Body Electric
In the long run, Galvani unwittingly helped the cause of the mecha-
nists by giving them something to attack. As long as the elan vital was
ephemeral, all you could say was that you couldn't find it. Once Galvani
said it was electricity, a detectable, measurable entity, there was a target
for experimentation. Actually, Baron Alexander von Humboldt, the ex-
plorer-naturalist who founded geology, proved in 1797 that Volta and
Galvani were both partly right. Bimetallic currents were real, but so was
spontaneous electricity from injured flesh. However, the mechanists had
the upper hand; Galvani's anonymous report and Humboldt's con-
firmation were overlooked. Galvani himself died penniless and bro-
kenhearted in 1798, soon after his home and property were confiscated
by the invading French, while Volta grew famous developing his storage
batteries under the auspices of Napoleon.
Then in the 1830s a professor of physics at Pisa, Carlo Matteucci,
using the newly invented galvanometer, which could measure fairly
small direct currents, came up with other evidence for animal electricity.
In a meticulous series of experiments lasting thirty-five years, he con-
clusively proved that the current of injury was real. However, he didn't
find it in the nervous system, only emanating from the wound surface,
so it couldn't be firmly related to the vital force.
The tale took another turn in the 1840s when Emil Du Bois-
Reymond, a physiology student in Berlin, read Matteucci's work. Du
Bois-Reymond went on to show that when a nerve was stimulated, an
impulse traveled along it. He measured the impulse electrically and an-
nounced his conclusion that it was a mass of "electromotive particles,"
like a current in a wire. Immediately he squared his shoulders, expecting
the mantle of glory to descend: "If I do not greatly deceive myself," he
wrote, "I have succeeded in realizing in full actuality . . . the hundred
years' dream of physicists and physiologists, to wit, the identity of the
nervous principle with electricity." But he had deceived himself. Soon it
was learned that the impulse traveled too slowly to be a current, and
that nerves didn't have the proper insulation or resistance to conduct
one, anyway. Any true current the size of the small measured impulse
wouldn't have made it through even a short nerve.
Julius Bernstein, a brilliant student of Du Bois-Reymond, resolved
the impasse in 1868 with his hypothesis of the "action potential." The
impulse wasn't a current, Bernstein said. It was a disturbance in the
ionic properties of the membrane, and it was this perturbation that trav-
eled along the nerve fiber, or axon.
The Bernstein hypothesis stated that the membrane could selectively
filter ions of different charges to the inside or outside of the cell. (Ions