PBODUCED BY A CONSTANT CURRENT. 37 



Experiment 22. + P = 30 ; P = 16 ; E = 16 ; y = 5 ; 



10 Meidinger, Rh. = 20,000 ; no paper under the nerve. 



The mechanical stimulus produces excessively slight contractions ; 

 the constant current only make-contractions. Under its influence the 

 contractions excited by the mechanical stimulus suddenly become of 

 maximal intensity, one might even say tetanic ; after interruption of 

 the current they instantly vanish. In order to apply the mechanical 

 stimulus quite close to the negative pole in this experiment as well 

 as in the two following, I led .the current to the nerve through a 

 strip of filter-paper moistened with a 0-6 % solution of common salt. 



Experiment 23. +P = 30 ; P = 12-5 ; E = 13 ; y 12 ; 

 10 Meidinger, Rk. = 20,000 ; no paper under the nerve. 



The mechanical stimulus produces quite small contractions, the 

 constant current make- and break-contractions. Under its influence 

 the contractions evoked by the mechanical stimulus are very strong, 

 almost tetanic. With interruption of the current they again decline, 

 but are still a little greater than they previously were. The same 

 action occurs if the current is once more closed. 



Experiment 24. +P = 33 ; P == 14 ; E = 14 ; TO Meidinger, 

 Rfi. = 20,000 ; y = 5. 



The mechanical stimulus elicits weak contractions ; the constant 

 current only a make- contraction. Under the influence of the constant 

 current the contractions produced by the mechanical stimulus reach 

 maximal height, and retain this all the time the current is closed. 

 After it is opened there appears first a diminution of the excitability, 

 after which the contractions resume their original height. 



9. The intrapolar changes of excitability at the positive pole 

 of an ascending current. 



The excitability of the nerve is lowered with all strengths of 

 the current, even with the weakest. This diminution does not 

 assume its full amount all at once, but the contractions fall off 

 gradually under the influence of the current, so that the first con- 

 tractions after contact is made, though considerably smaller than 

 those preceding them, are somewhat greater than their successors. 

 This lowered excitability lasts as long as the current is in action ; 

 yet it happens that the contractions meanwhile gradually increase, 

 though the increase is only trifling and often does not occur at 

 all. If the current is opened the contractions recur forthwith to 



