20 ANIMAL ELECTRICITY. LECTURE I. 



The first thought that suggests itself when one 

 has seen by what a surprisingly regular series of 

 electrical effects the nerve responds if regularly 

 interrogated at regular intervals, and when one has 

 satisfied oneself further that such electrical response is 

 physiological, is that we are in possession of a most 

 excellent test by which to recognise the action of 

 chemical reagents upon the physiological properties 

 of nerve. 



For the test is applied to nerve and to nerve only. 

 There is not, as when muscular contraction is used as 

 the indicator, any question as to the share borne by 

 muscle or by motor end plate. The experimental 

 isolation of the object of observation is complete. It 

 does not move. The excitation by which it is tested 

 does not exhaust its excitability. It is a subsidiary, 

 but by no means slight, advantage, that the photo- 

 graphic record of each and every observation can be 

 easily taken, and preserved for future reference, and 

 be as authoritative a century hence as it is to-day. 

 The nerve has recorded its own series of answers 

 during any treatment to which you may have chosen 

 to submit it ; it cannot give a false answer ; the worst 

 that may happen is that it may give some spurious 

 answer to a spurious question, or that we may for the 

 moment fail to correctly interpret the language in 

 which its answers are returned. 



A good instance to take in illustration will be to 

 compare the action of different ana;sthetics, and I will 



