Application of “Square Wave Analysis” to Bioelectric Studies1

As a whole the present paper deals with a method, based on the use of square shaped electrical waves, that permits the registration of even very transient electrical impedance changes in biological objects. Directly it is possible to record a) the “transient” and steady state D. C. resistance, b) the “high frequency” A. C. resistance, and also, after performing a procedure of “square wave analysis”, c) to evaluate the impedance values for any intermediate A. C. frequency. Thus the method allows the construction of “impedance locus diagrams” (according to GILDEMEISTER-LULLIES-COLE) of phenomena of short duration, as, for instance, the impedance changes in living objects in connection with electrical stimuli shocks. The paper is disposed as follows: In the introduction of the paper the theoretical relations are discussed which exist between the responses on sinusoidal alternating currents, square wave alternating currents and “rechteckige Stromstöse” (according to LULLIES). A practical procedure of harmonic analysis is then described, which enables the transformation of the square wave response into impedances to sinusoidal currents. As examples of possible applications are described: a) the response of a “model” circuit, b) the effects of NaCl and KCl solutions on frog skin, c) the effects of D. C. stimulation on frog skin.