MUSCLE-NERVE. 



the current enters the nerve. Immediately after the cessation of 

 the current, these conditions are reversed ; the irritability and con- 

 ductivity are increased at the anode and decreased at the kathode. 



\ 



FIG. ^.-Arrangement for Studying Effect of Constant Current on Irritability of 

 Nerve. Current running in direction of arrow is a descending current. Inductoria 

 (i and 2) connected with battery through current changer (3) in such a way that cur- 

 rent may be passed through primaries of either i or 2, so as to stimulate nerve (4) m 

 region of anelectrotonus, about anode (6), or in regions of kathelectrotonus, about 

 kathode (8). Nerve impulse indicated by twitch of muscle (5). Through Pohl's 

 commutator (7), with crosspieces in, the constant current maybe reversed and be- 

 come an ascending current, instead of a descending as shown in the figure. The 

 dotted line, running below the nerve at the anode and above at the kathode, repre- 

 sents, respectively, the diminution and increase in irritability of nerve in the anodic 

 and kathodic regions. 



[39] 



