506 



PROFESSOR C. R. MARSHALL ON THE 



previously described, that the paralysing influence of this group of substances increases 

 as we proceed from tetra-methyl-ammonium chloride to tetra-ethyl-ammonium 

 chloride. For isotonic solutions which, however, do not give a correct indication of 

 the relative activity of tetra-methyl-ammonium chloride and of tri-methyl-ethyl- 

 ammonium chloride owing to a certain time being necessary for penetration through 

 the muscle, the time required to paralyse the nerve-endings was for — 



Tetra-methyl-ammonium chloride, 1*12 per cent. 



Tri-methyl-ethyl-ammonium chloride, 1-26 ,, 

 Di-methyl-di-ethyl-ammonium chloride, 1*4 ,, 



Methyl-tri-ethyl-ammonium chloride, L55 „ 

 Tetra-ethyl-ammouium chloride, 169 ,, 



With smaller concentrations of the more powerful substances a truer indication of 

 the relative activity of these compounds is obtained. This is seen in the following 



4 to 5 minutes. 



5 



)> 



14 



)i 



22 



)» 



21 





Fig. 22. — Continuation of previous figure, showing terminal irritability of nerve. 

 N = nerve ; M = muscle. The numbers refer to position of secondary coil. 

 Time in ten seconds. 



table, which shows the time in minutes required by various concentrations of the 

 substances in Ringer's fluid to paralyse the nerve-endings to a moderately powerful 

 electrical stimulus (secondary coil at 12 cm.) : — 



Tetra-methyl-ammonium chloride . 012 p. c. = 5 min. OOl p. c. = 10 min. 00033 p. c. 

 Tri-methyl-ammonium chloride . . 0T3 „ = 6 „ 004 „ =20 „ 

 Dimethyl di-ethyl-ammonium chloride T4 „ =14 „ 0'28 „ =20 „ 



24 min. 



The action of these compounds on the contractile substance of the muscle itself, 

 as shown by direct stimulation, was similar in all cases. In isotonic solutions they 

 act as muscle poisons, and in the case of the sartorius immediately diminish the 

 irritability of the muscle, and quickly abolish it. In some experiments a slight 

 terminal irritability has continued for some time. The gastrocnemius is similarly 

 but less powerfully influenced. The toxicity falls markedly with diminution in con- 

 centration of the substance, and with one-fourth isotonic strength the irritability 

 may continue until next day. If a muscle is allowed to remain unstimulated in an 



