322 Dr. A. D. Waller and Miss S. C. M. Sow ton. [June 12, 



substances : choline and neurine pure, choline hydrochloride, and 

 neurine hydrochloride. These were used in solutions of 10 per cent, 

 or less, and in the case of the pure substances both unneutralised and 

 neutralised solutions were tried. Series of nerves were immersed 

 (a) for 1 minute, (b) for 30 minutes, the experiments being photo- 

 graphically recorded. At the end of each experiment the nerve was 

 replaced in physiological saline, and some hours later, usually the next 

 morning, having received a new transverse section, it was again tested 

 in order to ascertain whether any effect that had been recorded was 

 permanent or merely temporary. 



In making up solutions of choline the question arose as to 

 whether physiological saline or distilled water should be used. 

 Saline being inadmissible in the case of neurine, the comparisons to 

 be made would be more fair, it seemed, if all solutions were made with 

 distilled water. 



In working, however, with choline hydrochloride, a solution was 

 made up with saline, and a second one with distilled water, in order 

 by comparing the effects of the two, to estimate roughly what 

 proportion of any effect obtained should be attributed to the action 

 of the distilled water. In the course of former experiments some 

 attention had already been paid to the separate action of distilled 

 water upon nerve, and immersion for 30 minutes was found to diminish 

 its electromobility. But between the two choline hydrochloride 



FIG. 2. Distilled water. 



solutions no great difference of effect could be noticed. After this 

 first trial the solutions of both choline and neurine were made up 

 with distilled water only. 



A 1-minute bath of choline hydrochloride at 10 per cent, has little 

 or no effect upon nerve response. A 30-minute bath of the same 

 solution diminishes the deflection, but soakage for some hours in 

 physiological saline restores completely the electromobility of the 

 nerve. The drug then may be said to be active in strong solutions 

 applied for a considerable time it cannot be characterised as " toxic." 



With neurine hydrochloride in 10 per cent, solution the effect of a 

 1-minute bath is diminution of the electromobility of the nerve, similar 

 in degree to that observed after 30 minutes of choline hydrochloride 

 of the came strength, but the nerve treated with neurine gives after 



