CHEMICAL CONSTITUTION AND PHYSIOLOGICAL ACTION. 169 



an elective action for any special portion of the nerve. In the next experi- 

 ment, a much more limited portion of the nerve was protected from the poisonous 

 action. 



Experiment LVII. — In a frog, weighing 542 grains, the right gastrocnemius 

 muscle was exposed ; the muscle was separated from all its connections, 

 excepting its origin and insertion and the nerve-fibres that entered it. One- 

 sixth of a grain of sulphate of methyl-brucium, dissolved in ten minims of 

 distilled water, was then injected into the abdomen. In twenty minutes, a 

 condition of complete paralysis was present everywhere except in the right leg. 

 The two sciatic nerves were exposed, and on galvanising the left nerve, feeble 

 movements occurred in the right leg, and there only. When the right nerve was 

 galvanised, movements occurred in the right leg, which were observed to be solely 

 due to contractions in the right gastrocnemius muscle. 



In this experiment, the terminations of the sciatic nerve in the right gastroc- 

 nemius muscle were alone protected from the direct influence of sulphate of 

 methyl-brucium. This substance had access to all the other terminations of the 

 right sciatic nerve, to the trunk of this nerve, and to all the other nerves of the 

 body. No manifestation of vitality was obtained anywhere, except in the right 

 limb, and it was restricted to contractions of one muscle of that limb. As 

 these contractions could be produced by a stimulus originated in and conducted 

 along the nerve trunk, it is obvious that the vitality of this portion of the 

 nerve was not lost. And as the stimulus produced no effect on the termi- 

 nations of the nerves to which sulphate of methyl-brucium had access, while 

 it produced an effect on those that were protected from its direct influence, 

 it is evident that this poison acts on the peripheral terminations of the motor 



nerves. 



The physiological action of brucia is, therefore, completely changed by the 



addition of iodide or sulphate of methyl. It is also apparent that its activity as 



a poison is greatly lessened ; and the following table, which contains a succinct 



statement of some of the previously-mentioned facts, will clearly illustrate 



this : — 



