ACTION OF POISONS. 131 



operation being followed by syncope, and even 

 by stupor, with dilatation of the pupils, and 

 stertorous respiration, and continuing for several 

 minutes ; and there is, d priori, no evident reason 

 why the impression made on the nerves by so 

 powerful an agent as the hydrocyanic acid, or 

 the essential oil of bitter almonds, should not do 

 in one case what a slight mechanical injury does 

 in another. 



5. In another publication I have referred to 

 another class of cases, the phenomena of which 

 cannot be well explained except by attributing 

 them to an influence transmitted through the 

 medium of the nerves. Thus, in one instance, acid 

 in the stomach caused a severe pain in the foot, 

 which was immediately relieved by a dose of 

 alkali neutralizing the acid. In another instance 

 a violent pain in the ankle, with inability to 

 move, subsided immediately on the rejection of 

 some indigestible food from the stomach. * 



6. I have elsewhere adverted to the analogy 

 which exists between the operation of the 

 nervous power and that of electricity. The in- 

 fluence of volition is transmitted instantaneously 

 from the brain to the muscles, and impressions 

 on the sentient extremities of the nerves are 

 communicated to the brain, the nerves them- 

 selves answering the same purpose as the con- 

 ductors of an electric apparatus. The agent 

 in both instances is invisible, intangible, and 



* Lectures illustrative of certain Local Nervous Affections, 

 page 11. 



K 2 



