602 EDGAR L. GASTEIGER AND BERRY CAMPBELL 



TABLE I 



Summary of Relative Sensitivities 



Number Sural and saphenous 



24 



11 



Spot checks for C fibers 



C > B 



C >7>/i 



5>C 



slow > C 

 B>5>C 



axis was decreased to record the presence of C fibers after the vagal slow 

 fibers had been blocked and the fast A fibers were still conducting. 



The scope and range of responses in all experiments are presented in 

 Table I for the sural, saphenous and vagal nerves. The position of a fiber 

 group within a category of observations was based on the irradiation dose 

 required for SV'^r depression of nerve activity, and the number of experi- 

 ments which fitted each category is listed to the right of the category. All 

 experiments in which spot checks for C potentials were made are included 

 in the bottom section of the table. 



From these experiments, it is concluded that the A fibers of sural and 

 saphenous nerves show a decreasing sensiti\'ity to beta irradiation in the 

 following order: delta, gamma, and beta. Although inconclusive, the obser- 

 vations indicate that C fibers are less than or equal to the deltas in sensi- 

 tivity, but greater than the betas. 



Results from the vagal experiments show the slow fibers (delta and B) 

 to be more sensitive than the fast A fibers. In 3 experiments in which the 

 B fiber potential could be separated from the delta potential, the B fibers 

 displayed greater sensitivity. The vagal C fibers were studied in 7 experi- 

 ments by continuous recording and in 3 experiments by spot checks at the 

 end of the irradiation periods. In 8 cases C and slow fibers could be con- 

 trasted ; in 7 of them the C fibers proved to be less sensitive than the slow 

 fibers, and in 1 they were equal. In 6 cases where comparisons could be 



