138 



ANIMAL ELECTRICITY 



-LECTURE VI. 



the nerve Is from e to e' . e' is more anodic than e^ 

 i.e., more zincable, and the excitatory change gives 

 current in the nerve from e to e. 



Our second experiment is to show that a polarising 

 current is increased during excitation — undergoes a 

 positive variation. (Hermann). 



The connections are as in fig. 66, as being perhaps 

 a Htde more obvious than would have been the case 

 with polarising current, galvanometer and secondary 



Fig. 66. 



coil in one circuit connected with the nerve by a 

 single pair of electrodes. [The resistance boxes r. R., 

 used as shewn in figs. lo and ii on pages :^'^ and i"^, 

 enable us to take a convenient voltage (o'l to 0*5) for 

 the polarising current.] 



Using a Leclanche cell and having set the resist- 

 ances at 1000 and 14000 ohms respectively to get a 

 voltage of about o'l, I close the key in the polaris- 

 ing circuit giving current from e to e' in the nerve. 



