PHASE-SHIFTING A LUNAR RHYTHM IN PLANARIANS BY ALTERING THE HORIZONTAL MAGNETIC VECTOR

Abstract

1. It has been shown that a 180° shift in the direction of the horizontal vector of magnetism will effect a 180° shift in the phase of the monthly rhythm in geographical orientation in planarians. 2. The shift is essentially completed immediately when the reversed field has a strength of 0.05-gauss, or about 1/3 the earth's natural horizontal vector strength. 3. When the experimentally reversed magnetic field has a strength of 4.0-gauss, more than 20 times the earth's, the complete reversal of the rhythm requires as long as 15 minutes, following the removal of the experimental fields, during which time characteristic transients intervene. 4. Implications for the biological-clock problem of this demonstrated relationship between vector direction of one geophysical component, relative to the others, and phase relationship of a fundamental biological rhythm are discussed.