78 LAB OR A TOR Y G VIDE IN PH YS1OL O G V. 



tent of muscle contraction. Induce electrotonus, 

 stimulate again in region of anode. If the experiment 

 is successful the contraction will be found to be de- 

 creased or absent. 



The nerve is, at the point c, in a condition or anelec- 

 trotonus [descending extra polar anelectrotonus]. 



(2) Stimulate at m, or in the region of the kathode. 

 Withdraw polarizing current. After a few minutes 

 stimulate again at m. If the experiment is successful 

 the wave is higher in the former than in the latter 

 case. 



The stimulation was made in the region of the 

 kathode and the nerve in a condition of kathelectrotonus. 

 [Descending extrapolar kathelectrotonus.] 



(3) Adjust for ascending, polarizing current. 

 Stimulate at m, i. e., in the region of the anode. The 



contraction is weaker than in the normal nerve, or it 

 may be quite absent. This region is now in a condi- 

 tion of anelectrotonus. [Ascending extrapolar anelec 

 trotonus.] 



(4) Stimulate in the region of the kathode. The re- 

 sponse is probably weak. Withdraw the polarizing 

 current. Stimulate again in the region of the kathode. 

 The response is normal, i. e., it is greater than during 

 theelectrotonic condition. 



But in descending extrapolar kathelectrotonus the re- 

 sponse was greater than normal. In the experiment 

 just performed we stimulated in the region of ascend- 

 ing extrapjlar kathelectrotonus. Note that the polariz- 

 ing current is relatively strong. 



(5) Remove one cell from the battery and repeat (4.) 

 If the response to stimulation is still weaker with than 

 without the polarizing current, reduce the strength of 

 the polarizing current still farther by use of the simple 



