BRINK AND OTHERS: CHEMICAL EXCITATION OF NERVE 483 



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DURATION OF INTERVAL (MS.) 



Figure 23. The average number of impulses per second in a chemically excited single fiber (frog) 

 can be markedly increased, without much change in the fundamental penorl. 



Lower graph : Frequency of occurrence in a train of impulses of intervals having values indi- 

 cite.l en I lu- abscis.-iie. Stimulation Uv topical app.ication ol a fo.ution containjig sodium citrate. 

 The average number of conducted impulses per second was about 220. 



Upper graph : Similar anals sis ol a consecutive series of inipu..'-es recorded at height of increa^^ed 

 re^non^'e evoked hv cathodal po'arization of rhcmically treated region (see figures 12 and 13). 

 The average number per second of conducted impiilses was about 305. 



Some of these cycles of local change failed to initiate conducted im- 

 pulses, and, accordingly, some of the intervals between successive im- 

 pulses were integral multiples of the least time interval of 3.2 milli- 

 seconds. The average impulse frequency was 220 per second. 



