Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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electro-nerve current, i. e., when run in the same direction with it; but there is a diminution of the living electro-nerve current proper to the living organism in health when the artificial cur- rent is directed in the contrary direction, i. e., against the natu- ral nerve current. There is an important difference, then, to be observed between the tetanizing of a nerve and that of a muscle; the electro- tonus in the muscle being the result of a weakening or a nega- tive variation of the native electro-muscular current, whilst that in the nerves is connected with the appearance and the cessa- tion of the electro-tonic state, which is alone produced and maintained by the rapidly interrupted, and as rapidly and regu- larly alternated, electric current of induction. M. Dubois- Reymond has shown in this connection that the electro-tonic state of the nerve, excited directly, determines also in the neigh- boring nerves and their branches an electro-tonic state; but exactly the reverse of Us own. This has a significant i*emcdial worth, to be borne in mind in connection with this practice, that comes under the head of extra-polar workings of the current. It has been proved satisfactorily that whatever be the por- tion of any sensitive or motor nerve, that is positively polarized, there is immediately manifested a negative variation of the natural nervous current in all the remaining or unincludcd por- tions of that nerve, — a proof that the new influence is propa- gated through all nerves in all directions equally. This solves the great question, whether, in each class of nerves, the natural nervo-galvanic current is propagated only in one given direction, as from above downwards in the motor nerves, and from below upwards in the nerves of sensation. All kinds of nerves, then, as we have shown, conduct electricity in the same manner when under the influence of the foreign, galvanic, or Faradaic currents. We can recapitulate and sum up the following condensed con- clusions, much in the words of the great modern philosopher, M. De la Rive : — 1. "We may regard as demonstrated, and that in a decided manner, from a multiplicity of prodigious researches, that there does exist, both in the nerves and in the muscles of all living