LECT. XIV. XV. PRODUCTION OF NERVOUS FORCE. 295 



1. The nervous fluid is produced by the chemical actions of nutrition. 



2. This fluid, developed principally in the muscles, is diffused there, and 

 being- endowed with a repulsive force between its parts, like the electric 

 fluid, retains the elements of a muscular fibre in a state of repulsion analo- 

 gous to that presented by electrified bodies. 



3. When this nervous fluid ceases to be free in the muscle, the elements 

 of the muscular fibre mutually attract each other, as we see happens in 

 cadaveric rigidity. 



4. This nervous fluid enters continually into the nerves, and from them 

 passes to the brain, assuming in these bodies a new state which is no longer 

 that of the free fluid: in this manner it passes from the muscle to the nerve. 

 According to the quantity of this fluid which ceases to be free in the 

 muscle, the contraction is more or less strong. 



5. This state is that of the nervous current, or species of discharge which 

 proceeds from the nervous extremities to the brain, and returns in the con- 

 trary direction, by the act of the will. 



6. When this discharge takes place, muscular contraction ought to take 

 place, the fluid ceasing to be free in the muscles. 



7. This discharge of nervous fluid, acting as in the electric fish, ex- 

 plains the induced contraction ; in both cases, and by the same disposition 

 of parts, the nervous current produces a species of electric polarization of 

 the elements, either of the muscular, or of the electric apparatus : the dif- 

 ference of effects will be due to a different number of elements, to their 

 dimensions, &c. 



8. The electric current impedes the nervous discharge, if it be directed 

 in the contrary direction ; as in the direct current : the nervous fluid not 

 being able to enter and accumulate in the nerve, this loses its excitability. 

 The contrary takes place for the inverse current, which goes in the same 

 direction as that of the nervous discharge : the nervous fluid is found ac^ 

 cumulated in the nerve, and its excitability is augmented. J. P. 



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