PLATE CVII. 



The sh 

 of the galvanometer. 



KlU. 288. Diagram 

 illustrating the "natu- 

 ral " current in a piece 

 of muscle. The equator 

 is marked by the posi- 

 tive sign, and the mid- 

 points iif the transverse 

 sect ions by tlie nr-':il lv. 

 The arrows denote the 

 direction of the current 

 through the galvano- 

 meter. The larger cur\ es 

 denote the stronger cur- 

 rents, and lid' m-<i. 

 a,,, are two ^iiits OM the longitudinal surface equidistant from the 

 equator ; between them, therefore, there is no current. 



FIG. 289. Arrangenn 

 i*ed for the demolish 



nt of a nerve on i 

 rttion of the natu 



m-lH>larizable electrodes in 

 vl currents in a nerve. 



'..<>\ IVaLrram illustrating electrotonus. />';>, the polari/ing electrodes; 

 (('('. b I,', electrodes so placed as to show the effects of the natural current on 

 a g.-ilvanoincter at each end of the nerve wheo the polarizing current is in 

 the direction of the arrow* in the figure; the niitural current of n a' is iii- 

 < n-asrcl. as shown t>y the positive sign, while that of 4 b' is decreased, as shown 

 liy the negative sigu. 



