I04 ANIMAL ELECTRICITY. — LECTURE V. 



fallacy ; we must In the first place observe all care to 

 exclude It, and then we must take means of assuring 

 ourselves that it has been excluded. 



But even before this is done you will have noticed 

 a point that hints at something in the nerve other than 

 ordinary current-diffusion. The A. deflection and the 

 K. deflection are unequal — A. is greater than K. If 

 the two deflections had been by current-escape they 

 would have been equal. 



This does not indeed exclude all thought of 

 current-escape, for the latter may be present with 

 the peculiar something else that is becoming apparent 

 to us. So we shall use further means to try the 

 point. 



Let us anaesthetise the nerve by a little ether or 

 chloroform vapour, that will presumably distinguish 

 between a "physiological" and a "purely physical" 

 factor in the phenomenon, which in toto is, of course, 

 physical. That which is "physiological "?>., depen- 

 dent on the physico-chemical conditions peculiar to 

 the living state will be suppressed ; that which is 

 purely physical, i.e., dependent on the physical 

 properties of the dead nerve will persist. 



Ether, Chlorofoj^m. — Here, then, are a couple of 

 experiments In which this test has been applied, and 

 from which you may recognise the propriety of dis- 

 tinguishing two factors In the entire phenomenon — a 

 physiological factor, true An. and Kat., subject to 

 anaesthetic Influence — a purely physical factor, the 



