Abstract
It is generally supposed that a constant magnetic field has no effect upon life processes. Observers who have dealt with this question seem on the whole to be in quite general agreement that all attempts up to the present to demonstrate an effect have been complete failures, or else the conditions of the experiment have been too poorly defined to demonstrate an effect. In view of such a situation it is clear that any contrary statement of value must be supported by results obtained under clearly defined experimental conditions.
Along the bottom of a narrow, long glass trough 1×1.5×15 cm., through which a slow current of fresh sea water was kept flowing, were placed sets of internodes of the hydroid Obelia. 1 On opposite sides of one end of the trough were placed the N and S poles of an electromagnet, through which passed a direct electric current kept constant during any one experiment. The internodes were therefore fixed in definite positions along an intensity gradient of magnetic field. The small electric current (2 to 100 milliamperes in different experiments) passing through the coils of the magnet did not produce noticeable temperature change in the magnet; and the stream of running sea water had the same temperature to within 0.1° C. in all parts of the trough.
In brief, the experiments gave a clear proof that growth was entirely inhibited, and inhibition was followed by death in the high field-intensity opposite the poles of the magnet. The degree of inhibition decreased with increase in distance from the poles, until in a position in the outer end of the trough twelve centimeters from the center of the pole faces, no perceptible effect occurred.
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