. Eight lectures on the signs of life from their electrical aspect. Electrophysiology. 154 THE SIGNS OF LIFE r r of the voltasre taken is not -^ but -5 Note.—Obviously this yields only approximate results, since the voltage of a Leclanche is never quite volt, and the fraction Further, the internal resistance of the cell is not taken into account. The method is, however, sufficiently accurate, seeing that the principal error is a constant one and the variable error is negligible. In actual experiments it is advisable to have a standard com- pensator which will give values of .01, .001, .000
. Eight lectures on the signs of life from their electrical aspect. Electrophysiology. 154 THE SIGNS OF LIFE r r of the voltasre taken is not -^ but -5 Note.—Obviously this yields only approximate results, since the voltage of a Leclanche is never quite volt, and the fraction Further, the internal resistance of the cell is not taken into account. The method is, however, sufficiently accurate, seeing that the principal error is a constant one and the variable error is negligible. In actual experiments it is advisable to have a standard com- pensator which will give values of .01, .001, .0001 volt, independently of the compensator Fig. 57 A. Compensator to deliver TTTCinrth, n^th, or iJ u^h of a volt from a Leclanche cell (of volt). The comparison between experimental deflections and the standard deflection of known external voltage is not calculated to give the absolute value of internal of active tissue. The external circuit and galvanometer receive only a fraction of the total internal electromotive difference, which produces current partly through the internal conducting tissues, partly through the external (galvanometric) arc. Moreover, the time-relations of physiological action are generally such that internal effects of brief duration produce small external effects that cannot be standardised by a prolonged external voltage. Thus, ^i a nervous impulse with a duration of say sec. might, on a given instrument, produce the same deflection as a constant current from an of volt, but this would not indicate electromotive value of the nervous impulse. A closer approximation would be arrived at by making the comparison with. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Waller, Augustus Désiré, 1856-1922. New York : E. P. Dutton
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