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through the intervention of a very subtle fluid, or can the nerves, as has 

 been stated by some physiologists, be considered as vibrating cords ? This 

 last idea is so absurd, that one cannot help wondering it shduld so long 

 have been in vogue. A cord that it must vibrate, must be in a state of 

 tension, along the whole of its length, and fixed at both extremities* The 

 nerves are not in a state of tension, their extremities, in no degree fixed, 

 approach towards each other, or recede according to the difference of po- 

 sition, the tension, the turgescence, the fullness or collapse of the parts, 

 and vary constantly in their distance from each other. Besides, the ner- 

 vous cords, situated between pulps, at their origin, and at their termina- 

 tion, cannot be extended between these two points. The nervous fibre is 

 the softest, the least elastic of all the animal fibres ; when a nerve is divi- 

 vided, its two extremities, far from receding by contracting, project, on 

 the contrary, beyond each other ; the point of sections shows a number 

 of small granulations of medullary and nervous substance, which flows 

 through its minute membranous canals. Surrounded by parts to which 

 they are, to a certain degree, united, the nerves could not vibrate ; lastly, 

 admittingthe possibility of their being capable of vibrating-, the vibration 

 of a single filament ought to bring on that of all the rest, and carry con- 

 fusion and disorder in every motion and sensation. 



It is much more probable that the nerves act by means of subtle, invi- 

 sible, and impalpable fluid, to which the ancients gave the name of ani- 

 mal spirits: this fluid, unknown in its nature, and to be judged of only by 

 its effects, must be wonderfully minute, since it eludes all our means of 

 investigation. Does it entirely proceed from the brain, or is it equally 

 secreted, by the membranous envelopes of each nervous filament? (Neu- 

 rilemes, Reil.) To say the truth, one can bring no other proof of the ex- 

 istence of a nervous fluid, but the facility with which, by means of it, we 

 are enabled to explain the various phenomena of sensation, and its utility in 

 explaining these phenomena. These proofs, however, may not appeal- 

 completely satisfactory to those who are very strict, and who do not con- 

 sider as proved what is merely probable. 



Among the constituent principles of the atmosphere, there are gene- 

 rally diffused several fluids, such as the magnetic and electric fluids. 

 Might not these fluids, on entering with the air into the lungs, combine 

 with the arterial blood, and be conveyed, by means of it, to the brain, or 

 to the other organs ? Does not the vital action impart to them new qua- 

 lities, by making them undergo unknown combinations ? Do caloric and 

 oxygen enter into these combinations which endow fluids with a certain 

 vitality, and produce on them important changes, and which are not un- 

 derstood* ? Have not these conjectures acquired a certain degree of 

 probability, since the analogy of galvanism to electricity, at first suppos- 

 ed by the author of this discovery, has been confirmed, by the very curi- 

 ous experiments of Volta, repeated, commented, and explained, by all 

 the natural philosophers of the present day, in Europet ! 



The action of the nervous fluid takes place, from the extremity of the 



* Were it not for these changes, electricity, magnetism, and galvanism, would suffice 

 to restore life to an animal recently dead. Copland. 



J- Galvanism, as yet, has not realized the expectations of physiologists. Chemistry 

 has derived the greatest advantage from it. It is, at present, with M. M. Davy, The- 

 nard, and Gay-Lussac, the most powerful agent in the analysis of certain bodies. Cop- 

 land, 



