EFFECTS ON BIOELECTRIC ACTIVITY OF NERVES 



585 



12. 



X 1.0 



09 



Ct 0.8 



0.7 



0.6 



10 



20 



40 



50 



MINUTES OF X-IRRADIATION 



Fig. 9. Relative sensitivity (reciprocal of threshold stimulus voltage) of giant nerve 

 fibers of earthworm, plotted as a function of time of x-irradiation, as in Fig. 8. (24 

 experiments). 



responses of giant fibers are shown in Figs. 8 to 11. All experiments involved 

 records of activities on over 90 difTerent nerve fibers. An almost immediate 

 response to x-irradiation is evident; an enhancement of activity preceded 

 the deleterious effect of x-rays, which was manifested in suppression of 

 activity and ultimate block of activity. 



The median giant fibers were somewhat more sensitive to x-rays than 

 were the lateral giant fibers, as shown by the fact that the last activity of 

 the medians was recorded at 41 minutes, corresponding to 246 kr of x-rays, 

 whereas that of the laterals was recorded at 51 minutes, corresponding to 



