384 PROFESSOR C. R. MARSHALL ON THE 



two ligatures round the upper part of the left thigh, the injection of 0"8 mg. per 

 gramme of frog produced the following result when the nerves and muscles were 

 tested nineteen hours later. The numbers refer to the position of the secondary 

 coil : — 



Left gastrocnemius muscle, 18 '5 cm. Left sciatic nerve, 17 cm. 



Right gastrocnemius muscle, 17 cm. Right sciatic nerve, not irritable. 



In another experiment, in which the right thigh was ligatured, the muscles and 

 nerves were tested two and a half hours after the injection, with the following 

 result : — 



Right gastrocnemius muscle, 20"5 cm. Right sciatic nerve, 22'5 cm. 



Left gastrocnemius muscle, 19 cm. Left sciatic nerve, not irritable. 



If a dose insufficient to produce paralysis is given, the nerves may be found as 

 irritable as the muscles, or may be found as irritable as the muscles on one side and 

 less irritable on the other. Thus, in a frog to which O'l mg. per gramme body-weight 

 was given, the following results were obtained when the animal was pithed two 

 hours after the administration : — 



Left gastrocnemius muscle, 44'5 cm. Left sciatic nerve, 43*5 cm. 



Right gastrocnemius muscle, 44*5 cm. Right sciatic nerve 20 cm. 



But in these cases it was found that continued stimulation of the nerve induced 

 exhaustion more quickly than normally. The difference on the two sides, in those 

 cases in which it was present, was in all probability due to greater diffusion of 

 some of the solution along the lymph -sacs of one side, and consequently a greater 

 local effect. 



The greater paralysing influence on the nerve-endings as compared with the 

 muscle may also be shown by means of a muscle-nerve preparation. When such a 

 preparation is steeped in an isotonic solution of tetra-ethyl-ammonium chloride, the 

 nerve is found to be unirritable before the irritability of the muscle is much affected. 

 And as the application of an isotonic solution to the nerve-trunk does not materially 

 influence the irritability of the nerve, the paralysing action of the substance must be 

 attributed to an action on the so-called nerve-endings. 



The irregular muscular contractions and tremors have a similar location. Tillie * 

 states that a previous injection of curarin prevents the appearance of these tremors, 

 and I have corroborated his statement. Jacobj and Hagenberg t also obtained no 

 tremors with tetra-ethyl-ammonium iodide after curare had been given. Tillie 

 expressed the opinion that the tremors were due to an increased irritability of the 

 nerve-endings, and Jacobj and Hagenberg were of the same opinion, but no experi- 

 mental evidence is given to support this belief. It is not difficult to show that an 

 increased irritability of the nerves exists after the administration of small doses of 



* Loc. cit. t Loc. cit., p. 59. 



