406 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
studies were lent to me by Professor Simpson of the Enrico Fermi 
Institute of the University of Chicago. It was clearly evident that 
just as the crab daily cycles seemed to have been inverted between 
these two specific periods of study, so had the cosmic-ray cycles for 
the same two periods (the two broken-line curves). And furthermore, 
the general forms of the crab and radiation cycles were striking mir- 
ror images of one another. Similarly with the potatoes and seaweed, 
the forms of the metabolic cycles we had measured seemed clearly 
related in some manner to the cosmic-ray cycles. 
It is obvious that the specific forms of these cosmic-ray cycles could 
not have become evident to the living things in terms of fluctuations 
in any physical factors which are commonly conceded to influence 
them, such as light, humidity, and temperature. This would hold true 
even were the organisms exposed to the natural fluctuations of an 
open meadow. Clearly then, there must be still unidentified physical 
factors affecting life. And it now seems reasonable to postulate that 
these latter factors are very important to the living things in the timing 
of their rhythmic processes, or, in other words, in the operation of 
their clocks and calendars. 
The thesis supported in this article, namely, that during the timing 
of cycle lengths of the rhythms in animals and plants in so-called 
“constant conditions” the organisms are still continuously receiving 
from the external environment information about the natural geo- 
physical cycles, removes some of the romantic glamour inherent in 
the alternative view, that all living things must possess within them 
uncannily accurate clocks capable of measuring, independently, 
periods ranging in length from the day to the year. On the other 
hand, its implications are tremendous with respect to the potentialities 
involved through the demonstration that living things are sensitively 
responding to additional kinds of stimuli at energy levels so low that 
we have hitherto considered the living organism completely oblivious 
of them. These latter potentialities may soon loom importantly in 
many areas of biology and medicine, especially in such problems as 
animal navigation and behavior. 
The demonstration that the physical environment of living things 
is organized temporally in terms of still unknown subtle and highly 
pervasive forces which the living organisms can resolve encourages 
one to speculate that there may be some comparable subtle and per- 
vasive spatial organization of the environment which is contributing 
at least in a small way toward accounting for geographical distribu- 
tions or periodic migrations of organisms. 
