PKODUCED BY A CONSTANT CUKRENT. 41 



Experiment 29. +P = 30 ; P = 13 ; E = 16 ; y = 25. 



a. 3 Meidinger, ,Z?A. = 360. The mechanical stimulus occasions 

 weak muscular contractions ; the constant current only make-con- 

 tractions. Under its influence the contractions notably increase, and 

 sink to their former size when the current is opened. Presently these 

 quite disappear, but the contractions elicited under the influence of 

 the current retain their original strength nearly unaltered. 



b. E = 15-5; 3 Meidinger, ^. = 2,360. The nerve is stimulated 

 at a spot only -5 mm. distant from the preceding. The mechanical 

 stimulus here causes rather weak contractions, the polarising current 

 make- and break-contractions. Under its influence there follows a 

 distinct increase of the contractions. After the current is shut off 

 the contractions fall to their original amount. 



c. E = 1 6-5 ; 3 Meidinger, Rh. = 19,360. If the nerve is stimu- 

 lated i mm. higher up than in 6, and therefore -5 mm. higher than in a, 

 while the strength of the current is considerably raised, the latter now 

 exerts an insignificant and indeed hardly perceptible influence in 

 strengthening the contractions. 



d. E 15-7 5 6 Meidinger, Rh. = 19,360. The nerve is acted on 

 by the stimulus at a spot in close proximity to that previously 

 excited, and the strength of the current is so far raised as now to 

 cause a make- contraction and only a small break-contraction. In this 

 case the muscular contractions instantly disappear when the current 

 is closed. 



Experiment 30. +P = 34 ; P = 16 ; y = 13. 



a. E = 22; 3 Meidinger, Rh. = 340. The mechanical stimulus 

 produces rather weak muscular contractions, the constant current 

 make- but no break-contractions. Under its influence the con- 

 tractions elicited by the mechanical stimulus increase very consider- 

 ably. When the current is opened they decline to their original 

 height. 



6. J= 22; 3 Meidinger, Eh. = 2,000. The polarising current 

 brings about make- and break-contractions. Under its influence a 

 very considerable increase occurs in the contractions produced by the 

 mechanical stimulus, though by itself this calls forth only slight ones 

 in consequence of exhaustion of the nerve. 



c. E = 22 ; 3 Meidinger, Rh. = 20,000. With this greater strength 

 of the polarising current the contractions increase still further than 

 in a and 6. When the current is opened there is a transitory rise in 

 the height of the contractions as compared with that which they 

 attained before contact was made. 



