28 CHANGES OF EXCITABILITY IN NE.RVES 



c. The current is still weaker (2 Meidinger, Eh. = 30). The same 

 spots are stimulated as in 6, and under the same circumstances. 

 Now the contractions no longer cease, but they fall off perceptibly in 

 strength. On opening the current they regain their former intensity. 

 If it is still further weakened, the current produces no change in the 

 contractions. 



Experiment 9. 



+ P = 15 ; -P = 34 ; E = 17 ; 2 Meidinger, Eh. = 44 ; y = 30. 



a. The mechanical stimulus excites weak contractions. The 

 polarising current produces neither make- nor break-contractions. 

 Yet under its influence the muscular contractions instantaneously 

 vanish, and reappear in their former magnitude directly after the 

 next break of the current. 



6. -The nerve is excited with the same strength of mechanical 

 stimulus, but somewhat further from the pole (E = 19). With the 

 same intensity of the polarising current the muscular contractions 

 now do not disappear, but they fall off considerably in height. 

 When the current is broken they again reach their former 

 magnitude. 



Experiment 10. 



-f-P = I 7 ; P = 36 ; E == 20 ; 3 Meidinger, Eh. 5000 ; y = 30. 



The mechanical stimulus excites tolerably strong contractions ; 

 the polarising current produces both make- and break-contractions. 

 Under its influence the contractions disappear. Slight traces of them 

 may, however, be remarked during the first moments after inter- 

 ruption of the current. As soon as the current is opened the con- 

 tractions reappear and they are then somewhat stronger than they 

 were before closure, but sink by degrees to their original strength. 



Experiment 11. 



+ P = 15 ; -P = 34 ; E = 22-5 ; 3 Meidinger, Eh. = 4530 ; y = 30. 



a. The mechanical stimulus excites moderate contractions ; the 

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

 the contractions decline almost to complete evanescence. The decrease 

 is not BO great directly after the current is passed as it is later on. 

 On opening the current the contractions reappear in their original 

 intensity. The current is again closed, and now the muscular 

 contractions completely disappear ; but in the further course of the 

 experiment, the current continuing to pass, minute contractions 



