310 



Dr. A. D. Waller. 



[Mar. 12, 



Small quantities of ether and of chloroform vapour produce tem- 

 porary augmentation of excitability. 



C0 2 assists the anaesthetic and counteracts the toxic action of 

 CHCI3. 



Oxygen, hydrogen, nitrogen, carbon monoxide, nitrous oxide cause 

 little or no effect. 



Methane produces augmentation, hydrocyanic acid abolition. 



Carbon dioxide in small quantity causes primary augmentation, in 

 large quantity primary abolition or diminution, followed by secondary 

 augmentation. 



2. Action of Reagents Soluble in Normal Saline. 



The nerve is bathed for 1 minute in more or less dilute solutions 

 (acids, alkalis, neutral salts) and replaced upon the electrodes. 



Distilled water gradually abolishes excitability. 



Dilute acid solutions, M/40 to M/10, cause primary augmentation, 

 followed by gradual diminution. 



Stronger acid solutions, M/10 to M/5, cause primary diminution 

 and abolition. 



The effect of an acid follows acidity rather than avidity, but is 

 also specific. 



Decinormal acetic, nitric, and sulphuric acids have approximately 

 equal effects. 



As compared with the action of N/10 HN0 3 , or H 2 S0 4 , the action 

 of oxalic acid is less marked, that of phosphoric acid much less 

 marked ; that of lactic acid, on the other hand, is more marked. 

 Approximately equal effects are produced by N/10 nitric, N/5 phos- 

 phoric, and N/20 lactic. 



Alkalis. —Caustic potash is far more active than caustic soda. 

 Potassium salts are more active than sodium salts. 



Neutral Salts. — "With the view of ascertaining how far the action 

 of a neutral salt depends upon its acid or its basic moiety, the follow- 

 ing tabular comparison was effected, 



NH 4 C1. NH 4 Br. NHJ. 

 NaCl. NaBr. Nal. 

 KOI. KBr. KI. 



From which is concluded that the influence of the base predominates 

 in a total action due to the entire molecule. 



Many other salts have been tested, among which maybe mentioned 

 those of calcium and of mercury. 



Calcium chloride in M/10 solution augments the electrical response, 

 and antagonises potassium chloride, which diminishes or abolishes it. 



