postulate for the total field) was not well described by either worker, although Lund in one sentence
comes close to a solid-state electronic idea when he mentions "electron transfer across the cytoplasm
(in chain molecules)."
The work of Burr and Lund (as well as that of other workers) was mainly ignored by the
scientific community. Their measurements were suspect due to insensitive and artifact-producing
instrumentation, the potentials they measured were far below the "shock" level, and their theoretical
concepts were "fuzzy," hinting at the now discredited vitalism. The fact still remained however, that
they measured steady-state potentials on the surface of animals correlated with functional changes, very
similar to the measurements made in the brain by the neurophysiologists. The usual explanation-that
these were second-order phenomena, byproducts of underlying cellular metabolism-was unsatisfactory
from a number of aspects. First, it was not clear how such metabolic activity was translated into
electrical potentials, and second, a number of investigators had demonstrated that applied currents (well
below the level of heating) did influence general growth patterns in a nonrandom fashion.
Thus by the mid-1950's serious doubts began to be expressed concerning the ability of the
Bemstein semipermeable membrane hypothesis to explain all observed bioelectric phenomena both
within the central nervous system and in the body as a whole.
In 1960 we repeated Burr's measurements of the DC field on the surface of the intact
salamander using, however, the much more stable and sensitive instrumentation then available. Rather
than a simple dipole field, we found a complex field pattern with an obvious relationship to the
underlying anatomy of the central nervous system (17). Positive areas on the skin surface overlay areas
of cellular aggregation with the CNS, such as the brain and the brachial and lumbar enlargements of the
spinal cord, while the nerve trunks were increasingly negative as they proceeded distally away from the
spinal cord. This suggested that the potentials were related to the DC potentials of the CNS rather than
being generated by the total activity of all the cells of the organism. An immediate question was
whether current flowing within such a structure embedded within the volume conductor of the body
could produce such a field pattern on the surface of the animal. We found that when a CNS analog
(built of copper wire with solder junctions as generating sources at the brain and spinal cord
enlargements) was placed within a volume conductor of the same size and relative shape as a
salamander, the same pattern of potentials was measurable on the surface as was measured on the
living salamander. This indicated that the total CNS could be the source of the field potentials, but it
did not confirm that it had such an activity.
ELECTROMAGNETISM & LIFE - 26