190 



INFLUENCE OF TEMPERATURE ON BIOLOGICAL SYSTEMS 



tential. The precise relationship of the resting potential in bullfrog nerve 

 fibers with temperature is not known. In the squid giant axon this rela- 

 tionship has been determined with some degree of certainty (13) and 

 there appears to be no change in resting potential from 20°C down to 0°C. 



Table 2. Low sodium block of a fibers and recovery with 11 niM Nacl 



* The letters a, b, c, d, indicate the sequence in which the different stages were 

 carried out. 



t Where figure is not given recovery to 50% level did not occur. 



Another possibility is that the gain in sodium ions which nerve fibers 

 undergo at low temperature (25) could create an extra gradient against 

 which the sodium ions must move in generating an action potential. It 

 should be recalled, however, that the nerve employed for the experiment 

 shown in figure 8 was, prior to the test with NaCl at 11 mM, exposed for 11 

 minutes to a solution entirely lacking in NaCl. Under these conditions 



