THE CONDUCTIVITY BALANCE 493 



contact was on an unkilled, and the distal on a killed 

 area. The first of these experiments was on variation of 

 receptivity. The thermal stimulator was provided with mica 

 shields, so that the receptive area was strictly circumscribed 

 at the centre of the thermal platinum loop. Normal responses 

 were first taken ; the receptive area was next touched with 

 I per cent, solution of alcohol, and the modified responses 

 were recorded. The results are seen in fig. 302, which gives 



FIG. 302. Photographic Record of Effect of Alcohol Vapour on 

 Receptivity 



The three normal responses to the left are seen to be exalted after applica- 

 tion of ether on the receptive point. 



a striking demonstration of the increased receptivity induced 

 by dilute alcohol. 



The effect on conductivity, however, is in curious con- 

 trast to this. On applying I per cent, solution in the 

 conducting region between the stimulator and the proximal 

 contact, a very great diminution of the conducting power 

 is observed, as seen in fig. 303. It may be stated here 

 that a similar enhancement of receptive excitability, and 

 depression of conductivity, are found to be the result of the 

 action of alcohol in animal nerve also. In the next ex- 

 periment, it is the variation of responsivity under the action 

 of dilute alcohol which is tested. After taking the normal 



