Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

lias been thought by some, that the constant primary current, and also the secondary current, does not act by a true central reflex action, but rather by the painful excitation of the peri- pheric nerves, such as are pairing off with their fellows of mo- tory nerves, and thus causing contractions by a kind of local reflex action. But if this be so, how can we explain the fact just mentioned as to the Faradaic phenomenon? According to this view, when lightly applied electrodes with strong induction currents cover the region of a nerve, then there should be more contraction, because more pain. But we see that by pressing the electrodes deep into the flesh, the pain is less, while the con- traction is so much the greater. It cannot be an exclusive action, then, of that sort. We find that good electro-muscular contractions are not al- ways to be produced either through the employment of Faradaic or Galvanic currents even on the nerve trunk, or on a pure mo- tory nerve, until its branches in the muscles themselves have reacquired their excitability by the action of the current, i. e., by the extra-polar working of the current, which is possible even on the motory nerves ; but this is realized, probably, only under certain conditions of the peripheric extension workings pro- duced by the current. Polar alternatives are those alternating motions in the man- aging of the electrodes during a seance, that is simply the re- moval or disturbance of one electrode while the other remains, and then the removal of the latter while the former remains, and so on, either alternately, double alternately, or treble alter- nately ; i. e., three times lifting the one, and then the other three times, &c. By such manoeuvres we are enabled, by means of one and the same galvanic, or even electro-magnetic current, to ex- pose two different muscle groups, or nerve groups, in an unequal labile excitement — a means of great value in a portion of cases that present for treatment. Those phenomena which appear in very excitable muscles, belong to the local workings of current variations in the nerves and muscles together, as where a current is directed through the motory nerve peroneus, which occasions, even at its leaving, a contraction in the depending muscles;