A comparison of various methods of measuring the time-constant of accommodation of Nerve

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Abstract
In an earlier paper Hill (1936, a ) developed the theory of “accommodation” in excitable tissues. He pointed out that the measurement of its speed may be accomplished in a variety of ways. Experimental details of the method of determining the time-constant of “accommodation” (λ) in nerve, by excitation with exponentially rising currents, have been described by Solandt (1936). In the present paper the value of λ obtained by this method is compared ( a ) with that by alternating current excitation; ( b ) with that by “break” excitation at the anode at the end of a constant current pulse; and ( c ) with that by “make" excitation at the cathode at the end of a gap in a constant current. Excitation by linearly rising currents was not performed, because it is obvious that the value obtained for λ would not differ significantly from that obtained with exponentially rising currents. Method In all cases the sciatic-gastrocnemius preparation of the Hungarian bullfrog ( Rana esculnta ) was used. The experiments were performed during the winter months (November-February). Details of the treatment of the preparations prior to the determinations of λ are stated with the results. The composition of the normal Ringer’s solution used was 6·75 gm NaCl, 0·20 gm CaCl 2 , and 0·15 gm KC1 made to 1 litre with distilled water.

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