

PRODUCED BY A CONSTANT CURRENT. 31 



c. Rh. = 300. With increased strength of the current, on the 

 other hand, no change is produced in the magnitude of the con- 

 tractions. 



d. Rh. = 400. When the current is still further increased it 

 quite annuls the muscular contractions. Here be it observed that 

 in the experiments 6, c, d the same part of the nerve was used 

 (E = 24). 



e. The nerve is now stimulated somewhat higher up {E == 24). 

 Under the influence of the constant current, which is now of the 

 same strength as in d, the muscular contractions are, it is true, 

 diminished, but this diminution does not by a long way reach the 

 same amount as in d. 



f. Stimulation is now applied nearer to the negative pole (E = 25). 

 The mechanical stimulus now produces only slight contractions, 

 which under the influence of the same current as in d and e increase 

 by a very little. Throughout the experiment the strength of the 

 mechanical stimulus has been unaltered. 



Experiment 13. +P = n ; P = 33 ; 2 Meidinger. 



a. E = 15 ; Rh. = 90. The mechanical stimulus causes only small 

 contractions. The constant current produces a make- but no break- 

 contraction. Under its influence the contractions elicited by the 

 mechanical stimulus vanish forthwith. 



b. E = 1 8 ; Rh. = go. The mechanical stimulus causes only feeble 

 contractions. These are not modified by a constant current of the 

 same strength as in a. 



c. E = 1 8 ; Rh. = 200. Stimulation is continued at the same spot, 

 but the strength of the polarising current is increased. On closure, 

 the muscular contractions at once vanish, to reappear when the 

 current is opened. 



d. E = 29 ; Rh. = 200. The mechanical stimulus here excites fairly 

 powerful contractions, which are not in the least altered by the action 

 of a current having the same strength as in c. 



e. E = 16; Rh. = 60. Finally the nerve is stimulated close to the 

 positive pole. The strength of the polarising current is quite in- 

 considerable. When this is closed no change occurs in the strength 

 of the contractions. Throughout the experiment the mechanical 

 stimulus remained of the same strength. 



6. The extrapolar changes of excitability at the negative 

 pole of a descending current. 



The excitability of the nerve is considerably increased. This 



