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

ance; and again, that in proportion as the muscles are de- pending on that nerve, they take on a contraction which may he either tonic, i. e., without interruption, or whose actually existing variations escape observation from being covered up with the skin. Furthermore, " it is demonstrated in the living human being," says Dr. Remak, " that a constant primary galvanic current, as from thirty to fifty Danicll's elements, when directed, say through the nerve medianus in a downward course, produces the more pain and less extension of the limb ; while if an upward cur- rent is used on the same nerve, there is the less pain and more extension of the limb ; and, moreover, that while such a current is so running through the nerve medianus, according to the rule, and perhaps causing at first an extension of the arm and hand, there may appear in the same case, sometimes, a dropping of the hand, i. e., during the action of that same current; and this, again, may be quickly succeeded by a contraction, caused by a still further action of the same current. Again, where the elec- trodes are situated over the nerve trunk and its ramifications, in such a manner as to lead the current obliquely from the flexion side of the limb to the extension side, even if with a less cur- rent, there appears to be more effect than a stronger current produces when the current is directed so as to meet the nerve fibrils from without, inwards. And, again, while it is true that the skin offers a certain degree of resistance, still are we compelled to believe that the sentient nerves participate in the results that at first sight might be ascribed solely to the motor nerves; and, finally, that under certain circumstances, it requires but a relatively small fibre, nerve, or central excitement, to change a simple current closing twitch into a true tonic contrac- tion. Electro-tonic contractions do sometimes appear to set in, without the participation of the sentient nerves, or of the central organs; but they manifestly more generally come from joint ef- fects on the sentient and motor nerves, being manifested not only in the reach of the nerves excited, but also in the antagonizing muscles ; and this phenomenon cannot be satisfactorily explained in any other way. The central in-working of the constant