Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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electric state is modified by every kind of excitation there is produced through the nerves. "We know that the muscles have likewise a natural electric state, which, too, is modified every time there is a contraction. Now, in the absence of excitation in the nerve and of contraction in the muscle, there must be a certain equilibrium, which consists in the circulation of native internal electric currents, together with the minute chemical processes there going on, the first and controlling cause of which is, the vital force. This gives to all organic molecules, which are naturally bi-polar, the arrangement necessary to the estab- lishment of these natural nerve and muscle currents ; but when once established, they are probably reciprocally sustained, that is, self-sustained by the said chemical action, that is as every where present in the body as life itself, accompanies vitality, and which it perhaps, in part at least, again of itself determines. Thus is life transmitted by the nerves through means of their nervo-elcctric state, as found in their normal or healthy condi- tion of vitality ; and from this there results, in all the muscles and tissues of the living human organism, an analogous electric state and process, but with certain differences, due, as we have shown, to the different nature or function of these divisions of the living body. When the natural electric state of a nerve is modified by any cause whatever, the equilibrium is destroyed, and there results some sort of sensation or contraction, or, more usually, both. When this arises from the nervous centre, it appears that the polarization of the telegraphing nerve then on duty is brought about longitudinally; i. e., from one extremity to the other, just as is every conducting body that is traversed by an electric current, in such a manner that the negative pole of the molecules is turned towards the centre, while the positive is towards the muscles. This is just what would result from the action of a galvanic current travelling in the direction of the nervous ramification ; i. e., from the head towards the muscles. This it is that explains why an electric current run in this direc- tion, favors the contraction more than when run in the opposite direction. Then, again, if the influence exerted upon the nerve, instead of coming from the brain, rather comes from the mus-