Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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electro-tonic; whence results the production of a current that, according to its direction, either increases or diminishes the effect of the ordinary natural electro-nerve current. Then this electro-tonic state of the nerve, that may also be imparted to its depending muscles, is a commencement of electrolization ; it thus brings about a contraction, both by its arising or appearing at the moment when the circuit is made, and then by disappear- ing again at the moment when the current is broken. If now we compare together these facts, that are proved by our electro-physiological experiences thus far, we find that we arrive at some further very remarkable and valuable conclu- sions ; and first, we observe that when we act by means of a strong, steady, primary current, upon the nerve trunks of a living person, then there is, at the very commencement of the trial, a contraction of the limb, and a manifestation of real pain; and this also at the moment when the circuit is broken, as well as at the moment when it was closed or made ; and that these results obtain, whatever may be the direction of the current em- ployed. But on continuing these trials for a certain longer time,— shorter in proportion as the current employed is the more in- tense,— we find that there exists a difference between the effects, according as the current travels in the one direction or in the other, and according also as the circuit is closed or opened. When the current is directed downward, i. e., from the head and spine in the direction of the ramification of the nerves, the effect is limited to the contraction of the muscle, muscle group, or whole limb, at the moment vjhen the circuit is closed. And when the circuit is again opened, the effects are limited, or mainly directed to the contraction of the muscles of the back, which are accompanied with pain. But if the poles of the battery are now reversed, so as to send the current in what is called the inverse direction, or upwards and towards the spine and brain, and thus contrary to the nervous ramifica- tion, then the order of the phenomenon is not only reversed, but also modified. The closing of the circuit now, causes the con- traction of the muscles of the back, which is accompanied