182 



INFLUENCE OF TEMPERATURE OX BIOLOGICAL SYSTEMS 



that activity could be restored by the simple maneuver of washing out 

 the nerve with oxygen-free Ringer's solution. Feng, Hsu and Liu con- 

 cluded that recovery was simply the result of washing away the potassium 

 which leaked out of the nerve fibers and accumulated during the period 

 of anoxia. A similar experiment and conclusion was published by Shanes 

 (231 for the case of sciuid and crab nerve fibers. 



RESPONSES TO POTASSIUM — A FIBERS 



Whatever is the exact nature of the secondary decline in action po- 

 tential, it is clear that low temperature experiments were complicated by 



* The letters a, b, c, d indicate the sequence in which the different stage.s were 

 carried out. 



t Relative to the KCl concentration present in Ringer's solution. 



the fact that activity was not constant with time. Because of this complica- 

 tion experiments were designed which recjuired only relatively short periods 

 of time (less that 20 minutes) and a condition of acceptance of results 

 was the occurrence of at least 80% recovery of spike height after washing 

 with Ringer's solution. These conditions meant that only desheathed nerves 

 could be employed since similar experiments with sheathed preparations 

 recjuired several hours for completion. 



Low temperature caused a very marked acceleration in the rate of 

 block of A fibers by Ringer's solution containing excess potassium, i.e. 

 eight to nine times the normal KCl of Ringer's fluid. In six experiments, 

 for example (table I), the time to reduce the A wave to 50% of its initial 

 value (value at time of addition of test solution) was, at normal tem- 



