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Dr. A. D. Waller. Influence of Alterations of 



Electrotonic after-currents, A' and K', when present to any marked 

 degree, are opposed to the previous electrotonic currents A and K. 

 Designating A and K respectively as positive and negative, the 

 after-currents A' and K' are respectively negative and positive. Such 

 after-currents are in general modified by previous rise of tempera- 

 ture, which gives rise to an evident A' (negative) in a nerve which 

 previously gave no marked A', and abolishes a K' (positive) that 

 may previously have been present. Experiment 2366 exhibits the 

 development of an evident negative A' subsequent to heating of the 

 nerve. Experiment 2322 exhibits the abolition of a positive K', 

 evident previous to heating of the nerve. 



A fall of temperature causes an increase of the A current and, 

 in less degree, of the K current; by reason of the diminution of 

 resistance that takes place with lowered temperature, the increase of 

 A is more marked than is apparent upon the record, and the smaller 

 increase of K is quite masked by the diminution of resistance. The 

 quotient A/K is augmented. At a temperature of 4 to 6 both 

 currents are somewhat suddenly abolished ; this abolition may be 

 complete and final, no recovery taking place, or it may be temporary, 

 being succeeded by imperfect recovery as the nerve temperature 

 returns towards normal. It is noteworthy that the A and K currents 

 are not abolished at suddenly, and all but finally abolished at 4 



