ICHIJI TASAKI AND COXSTANTINE S. SPYROPOULOS 219 



SUMMARY 



The effects of changes in temperature and hydrostatic pressure upon 

 tlie frog (or toad) single myelinated nerve fiber and the squid giant axon 

 are reviewed. The material presented was obtained partly from observa- 

 tions published by other workers and partly from the authors' recent ob- 

 servations. Special emphasis is placed on the experiments made with in- 

 ternal stimulating and recording electrodes in the squid axon and on the 

 observations carried out with single-node preparations of the toad. 



The effects of temperature are discussed with reference to 1 ) the resting 

 potential, 2) the capacity and resistance of the resting membrane, 3) the 

 resistance of the axoplasm, 4) the size and shape of the action potential, 

 5) the time course of the action current, 6) the membrane resistance during 

 activity, 7) tliresholds and 8) the conduction velocity. 



The effects of high hydrostatic pressures upon the squid giant axon and 

 upon the toad nerve fiber are discussed and, in particular, a reversible 

 prolongation of the duration of the action potential (up to 4-fold increase 

 at high pressures) at the main feature. A short discussion is given of the 

 temperature and pressure dependence of the effects of narcotics on the 

 nerve fiber. 



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