1903.] Action of Choliiic, Neu-rine, Muscarine, and Betaine. 331 



immersed for 30 minutes in the same solution, with the result, in the 

 first case, of diminution followed by recovery, in the second case, of 

 abolition with no subsequent recovery. In 3617 the 30-minute bath 

 was of the same strength as before, its effect was immediate abolition, 

 but the nerve gave a deflection the next morning. In 3623 there was 

 also immediate abolition, but in this case it was final. Nos. 3625 and 

 3627 may also be contrasted, in each case 30 minutes immersion in a 

 4-per cent, solution produced a slight augmentation of response, but 

 tested the next morning the one gave a deflection and the other none. 

 It would appear, therefore, that neurine hydrochloride is much more 

 suitable for such experiments as these than neutralised neurine. We 

 should mention that the frogs were in bad condition at the time these 

 experiments were made, the weather being very hot. But this 

 element of uncertainty would not alone account for the marked 

 inequalities noticed. 



Betaine Hydrochlwide. We made use of two samples of this sub- 

 stance, one coming from Merck's factory, the other from the laboratory 

 of Professor Boehm. The salt in each case when dissolved in 10-per 

 cent, solution in normal saline had a strongly acid reaction, requiring 

 for neutralisation half its volume of normal soda solution. 



The effects of unneutralised solutions at 10, 5, 4, 2, and 1 per cent, 

 are therefore partly or wholly acidic effects by 0'50, 0'25, 0'20, O'lO, 

 0'05 solutions of normal acid. We did not, however, work with these, 

 but with neutralised solutions. 



Method. Nerve. The excised sciatic nerve of frog, kept not longer 

 than 24 hours in physiological saline, is laid across two pairs of 

 unpolarisable electrodes in a moist chamber. The normal excitatory 

 effect (negative variation) is observed, preferably after as well as before 

 the cut end of the nerve has been refreshed by a new transverse section. 

 The nerve is then put to soak in the experimental solution, and from 

 time to time replaced upon the electrodes to be tested as before. If, 

 and when the excitatory effect is abolished, both before and after a 

 fresh transverse section, the nerve is put to soak in physiological 

 saline, and from time to time tested as before for a possible recovery of 

 electromobility. 



Proceeding thus we are enabled to qualify any given solution as 

 being: 1 inert or weak, 2 moderately active, 3 strong according as 

 the electromobility of the nerve is : 1 unaffected or little affected by 

 the solution, 2 abolished by the solution and restored by soakage 

 in physiological saline, 3 3 abolished by the solution and not restored 

 in saline. 



The circumstances of experiment, strength, and duration of excita- 

 tion, distance between electrodes, are, of course, maintained unvaried. 

 The unavoidable variations of frogs and of their nerves are far less 

 serious than might have been expected ; the nerves are removed with 



