254 NERVOUS FORCE. LECT. XIV. XV. 



LECTURES XIV. AND XV. 



NERVOUS FORCE. 



ARGUMENT. Characters of the nervous force ; the cerebro spinal system 

 and its action; the ganglionic system, and its action. 



Effects produced by electric irritation of the nerves, compared with those 

 caused by other stimulants. 



Analogy between the nervous force and the electric current. No evidence 

 of an electric current in the nerves of a living animal. The nerves do 

 not present the necessary conditions for such a current. Relation o^ 

 the nervous force to electricity. Induced contraction ; illustrative ex- 

 periments; facts favourable to the opinion, that it is caused by an electric 

 discharge from contracting muscles ; disproof of Liebig's hypothesis of 

 muscular contraction ; failure to detect the development of electricity 

 during contraction. New investigations of the induced contraction ; it 

 is only excited by a contracting muscle. Influence of substances in- 

 terposed between the contracting muscle and the nerve of the galvano- 

 scopic frog. Hypothesis to explain induced contraction. 



Production of nervous force ; mechanical power obtained by the conver- 

 sion of chemical action into heat, electricity, and nervous force. 



It may, perhaps, appear strange and almost rash for me 

 to notice the nervous force, or agent, in a course of lectures 

 on the physical phenomena of living beings; but I hope to 

 prove, by the considerations which will follow, that the 

 subject is not out of place here ; and that if, in treatises on 

 physics, the chapter consecrated to the general analogies 

 existing between caloric, electricity, and light, is the most 

 important, and in some respects the most philosophical, so 

 likewise will this lecture possess analogous advantages, at 

 least in its high importance. 



