The Circuit of Awareness 107
had come. That shouldn't have mattered—the lab temperature was the
same all year, and the frogs didn't stop eating and hibernate as they
would have in the wild—but there was a difference. The frogs' voltages
were much lower, they stayed unconscious longer with the standard dose
of anesthetic, and their blood vessels were much more fragile. Did they
somehow sense the winter?
If the DC system was as we theorized, it would be influenced by
external magnetic fields. In the Hall-effect experiment I'd already shown
that it was, but I'd used a strong field, measuring thousands of gauss.
The earth's magnetic field is only about half a gauss, but it does vary in
a yearly cycle. At the time there was another scientist who was saying
this weak field had major effects on all life. Frank A. Brown, a North-
western University biologist who was studying the ubiquitous phenome-
non of biological cycles—wavelike changes in metabolic functions, such
as the alternation of sleep and wakefulness—was claiming that similar
rhythms in the earth's magnetic field served as timers for the rhythms of
life. Even though his evidence was good, no one paid any attention to
him in the early sixties, but it seemed to me that we had something to
offer Brown's effort. We had a link by means of which the effect could
occur.
I wrote up the sciatic nerve measurements and added the observation
on winter frogs. I sent it to Science but got it back immediately. I guess
the editors had second thoughts after running my paper on the Hall
effect. Next I tried the even better British equivalent, Nature, which
took it. This time I also got some reprint requests. More important, the
report led to correspondence with Frank Brown, beginning years of mu-
tual feedback that helped bring about the discoveries described in Chap-
ter 14.
I thought of one more way we could check whether the current in the
nerves was semiconducting. We could freeze a section of nerve between
the electrodes. If the current was carried by ions, they would be frozen
in place and the voltage would drop to zero. However, if the charge
carriers were electrons in some sort of semiconducting lattice, their mo-
bility would be enhanced by freezing and the voltage would rise.
It worked. Each time I touched the nerve with a small glass tube
filled with liquid nitrogen, the voltage shot upward. But perhaps I was
damaging the nerve with the glass tube or through the freezing itself.
Maybe the increase was merely a current of injury. To check, we simply
cut the nerve near the spinal cord; the voltage gradient on the nerve
went to zero, and then we applied the liquid nitrogen again. If the cold
was really enhancing a semiconducting current, we should find no volt-