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PROFESSOR C. R. MARSHALL ON THE 



curve obtained from direct stimulation with the coil at cm. has been an unbroken 

 line, but the form shown with superadded contractions was not uncommon. 



Methyl-tri-ethyl-ammonium Chloride. — Isotonic or slightly hypertonic solutions 

 of this substance also caused no contracture when applied to a sartorius, but in the 

 presence of ten per cent, alcohol slight contracture was produced. The effect on the 

 irritability of the sartorius was the same as that of tetra-ethyl-ammonium chloride, 



Fig. 18. — Effect of 1*55 per cent, methyl-tri-ethyl-ammouium chloride on irritability of gastrocnemius of frog to direct and 

 indirect stimulation. Description as in fig. 14. Between the first and second parts there is an interval of ten'minutes ; 

 between the second and third parts an interval of five minutes, x §. 



except in the presence of ten per cent, alcohol, -when it seemed to be slightly ^jless. 

 The action of an isotonic solution on the sciatic-gastrocnemius preparation is shown 

 in fig. 18. As will be seen, the nerve-endings were paralysed to break shocks with 

 the secondary coil at 12 cm. in seventeen minutes, the muscle, when stimulated 

 directly, showing at this time considerable irritability. 



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Fig. 19. — Effect of 1'69 per cent, tetra-ethyl-ammonium chloride on irritability of gastrocnemius of frog. Description as in fig. 14. 

 An interval of fourteen minutes occurred between the two parts of the tracing. 



Tetra-ethyl-ammonium Chloride. — It was mentioned in a previous communica- 

 tion that isotonic or slightly hypertonic solutions of tetra-ethyl-ammonium chloride 

 caused no contracture when a sartorius was immersed in them, and it is only necessary 

 to add that no contracture was obtained even when ten per cent, alcohol was present 

 in the solution. Isotonic solutions, however, quickly abolish the irritability of the 

 sartorius, usually within five to six minutes, and in the presence of ten per cent, 

 alcohol within two to three minutes. 



The gastrocnemius is less quickly affected. The influence of an isotonic solution 

 on the irritability of this muscle and its nerve is shown in fig. 19. The nerve-endings 



C 



