Abstract
1. Introductory .—When a steady electric current is passed through a drop of pond scum rich in animal and vegetable organisms, two opposite movements of migration of the living cells will in general be observed. Diatoms and unicellular algae, for example, move towards the negative pole, amœboid animal organisms to the positive. The clearness of the effect is often confused by the presence of anchored and skeleton cells of either kind, and the case of pond scum is only given because the effect to be described was first observed in this way. Early in 1904 it was desired to find an indicator for the qualitative detection of voltage gradient in liquids in fields of microscopic dimensions. The orientation of long diatoms into line with the current was anticipated from the known behaviour of bacteria in an alternating field, and found to occur. In steady, that is unidirectional, fields they not only orientate but move along the line of current-flow to the negative pole. They therefore serve in two ways to indicate the presence of a steady current in the liquid.
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Schedule a callMore From: Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character
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