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Magnetic Measurements 



I. Magnetic Effects in Biology 



Constant or slowly varying magnetic fields are not detected directly by 

 any of the human senses. As such, magnetic fields are different from 

 other physical changes, many of which act as external stimuli. Light, 

 sound, heat, pressure, acceleration, gravitational forces, electrical 

 potentials, and chemicals — all may be perceived directly by at least one 

 of the human sensory organs. There is no theoretical reason for this 

 insensitivity to magnetic fields. Perhaps there are other organisms in a 

 different place in the cosmos which do sense magnetic fields. Some 

 persons have believed that homing pigeons could sense the earth's 

 magnetic field and could use it as a guide. 



The belief continues to exist among a small minority of scientific 

 investigators that magnetic fields can affect living organisms. Several 

 papers have been presented at technical meetings describing subtle 

 effects claimed in animals (usually rats) raised in high magnetic fields. 

 No changes reported in the past due to magnetic fields have ever been 

 confirmed. 



There appears to be no sensory or metabolic response to magnetic 

 fields. Nonetheless, magnetic effects can be used to study the properties 

 of biochemical molecules, particularly a small group called paramagnetic 

 molecules. These possess a net magnetic dipole moment which tends to 



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