Abstract
The electrical resistance of an ordinary conductor is independent of the magnitude or direction of a current sent through it, and a current may pass with equal ease in either direction. There have been suggestions, however, that in a nerve fiber membrane, current may pass more easily in one direction than in the other, or that the nerve fiber membrane behaves as a rectifier rather than a simple resistance.
Recently, Cole and Baker, 1 and Cole and Curtis 2 demonstrated rectification in the squid axon, using alternating current bridge methods and the needle electrode technic. Another paper, Cole, 3 shows that the previous failure of Cole and Hodgkin 4 to observe rectification in this axon was due to the fact that only small currents had been used and to the fact that the effect under the anode was approximately equal and opposite to the effect under the cathode, thus neutralizing it.
By killing one end of the nerve fiber, neutralization of rectification under one electrode by that under the other can be avoided, and it should be possible to observe rectification directly by means of a much simpler technic involving a direct current Wheatstone bridge.
The giant nerve fiber of the hindmost stellar nerve of the squid, Loligo pealii, was used throughout the experiments. It was carefully dissected away from the smaller nerve fibers under sea water with the aid of a binocular microscope. Immediately after dissection the axon was threaded through a glass U tube filled with oil. Then the U tube was suspended by means of a glass rod cemented to it in such a way that one end of the fiber dipped into sea water, where it remained in good condition for many hours, and the other end into KC1 isosmotic with sea water (0.52 M), which injured that end.
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