cyclic phenomena.
Biological Cycles
The biologist is confronted with a bewildering variety of form, function and complexity in
living things, from single-celled organisms such as amoebas to human beings. Beyond being composed
of chemical compounds containing carbon and equipped with the capacity of self-replication, living
things would appear to share few attributes. Over the past few decades however, it has become
increasingly evident that all living things from the simplest plant to man possess an innate rhythmicity
termed biological cycles. The sleep-wakefulness cycle is part of the human experience and superficially
appears to be associated with the solar day, just as the human menstrual cycles seems to be correlated
with the lunar month. However, the full complexity and richness of the living tides have only recently
been recognized. Upon scientific examination, there is a surprising uniformity of rhythmicity which
finds its counterpart in the tidal fluctuations in the earth's electromagnetic field. The study of these
phenomena has become a scientific discipline in its own right. It is not the purpose of this section to
study in detail all the complexities of modern chronobiology. Rather, we will hope to review the basic
uniformity that underlies this general characteristic of living things and its relationship to the earth's
normal electromagnetic field.
Much of our present understanding in this area is due to the patient and persistent work of one
man, Dr. Frank Brown, Morrison Professor of Biology at Northwestern University. After a
distinguished career in investigative endocrinology, he became interested in the relatively neglected
field of biocycles in the mid-1950's. At that time the innate nature of these phenomena had been shown.
It was common knowledge that organisms kept in the laboratory under constant conditions such as light
and temperature maintained a basic rhythmicity, with a period close to 24 hours; hence the generic
term, "circadian (about a day) rhythm."
This basic rhythm in the case of plants was strongly influenced by light and in the case of
organisms living in the intertidal zone of the seashore, by the lunar tides. For example, oysters open
their shells to feed as the tide comes in, covering them with water, and close them as the tide recedes. A
seemingly simple observation with an obvious explanation-the depth of water determined the opening
and closing. But this was not so. Oysters placed in the laboratory with a constant depth of water and
constant light and temperature still continued to open and close their shells in synchrony with their
fellows on the tidal flats. Somehow they received the timing signal or they had an internal clock
mechanism.
In 1954 Brown performed an important experiment (10): he flew oysters in a light-tight box
from the seashore at New Haven, Connecticut to Evanston, Illinois and installed them in the same
controlled circumstances there. At first the oysters continued to open and close in synchrony with the
tides at New Haven. However, gradually over a period of a few weeks the phase of the open-close
cycle shifted to coincide with the tidal pattern at Evanston, were it on a seacoast! Devoid of all known
positional cues, possessed of only the most rudimentary senses, the oysters somehow "knew" they had
been displaced almost a thousand miles westward in space. This was probably the first scientific
description of "jet lag!" What factor in the environment could possibly penetrate the laboratory and
provide such precise positional information?
Many years before, at the close of the nineteenth century, it had been noted that the earth's
normal magnetic field fluctuated with a lunar tidal pattern. This had led Arrhenius to postulate that
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