114 PHYSIOLOGY OF ORGANIC LIFE. 



effects are accomplished tli rough the medium 

 of a subtle fluid which the nerves contain, as 

 Sir ISAAC NEWTON and others with great pro- 

 bability of truth have asserted, or according to 

 the opinion of some, by vibrations excited 

 through nerves of a solid fabric, like thrills on 

 a brass wire, is not only a matter of hypothesis, 

 but is as unknown to the best physiologist, as 

 it is to the rudest barbarian.* With respect to- 

 the cause of motion, although the subject has 

 occupied the attention of many ingenious 

 and inquiring men, at different times ; we pos- 

 sess tfo other knowledge of it, than that the 

 muscles are the agents by which motion is 

 produced ; but of the cause why, we continue 

 in the most profc aid ignorance. 



.The ignorance, at present existing, of thr 

 functions which I have mentioned, are especial- 

 ly extended to those of consciousness. Al- 

 though the brain is the organ in which coiir 



* The horrid cruelties which continue to be practised by 

 the Galvanic fire, and other means, on the gciatic nerves of 

 frogs, rather favor the former hypothesis; the experiment 

 once made, has ascertained all that ran be known from it, and 

 the fact might, therefore, be mentioned, but certainly ought 

 not to be repeated (as it is so often done) in order to produce 

 a Sort of stage effect, and to gratify ignorant curiosity. Little 

 did LORD BACON suppose, that the system of induction which 

 .he introduced, would have been converted into a system of 

 .torturf. 



