582 



C. S. BACHOFER 



20 



20 40 



MINUTES 



60 



80 



Fig. 6. Comparison of effect of x-irradiation on rat caudal nerves in vitro and 

 in situ. Values are based on 25 in vitro and 28 in situ experiments. Dose rate: 6 

 kr per min. 



in response to supramaximal square-wave stimuli of 10"'' sec duration at 

 2 minute intervals (Fig. 6) . The mean absolute values at zero time for spike 

 amplitude were 4.27 mv for in vitro preparations and 4.85 mv for in situ 

 preparations. The absolute values at zero time for conduction velocity 

 were 26.2 m/sec for i?i vitro preparations and 27.5 m/sec for in situ prep- 

 arations. A comparison of the cui'ves shows a striking similarity between 

 in vivo and in vitro preparations. The minor differences were, chiefly, 



