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

tro-magnetic currents, can be most easily produced by changing the position of one or botb tbe electrodes tip or down on the nerve course, or over the muscle fibres, so as to increase and diminish alternately the distance, and hence the amount of sub- stance and resistance there is betiveen the poles. This, I find, often proves actively remedial, even where it does not cause any visible contractions ; and that too, sometimes, where very active convulsive twitcbings had been repeatedly produced in the same case previously by " hap-hazard " magneto-electric treatments, that were attended with no durable improvement, but perhaps only with a diminishing of the little voluntary capability that before remained ; also, where stabile primary currents, of equal strength, refused to act. Labile contractions are those which are produced in the mus- cles, or in the muscle nerves, simply by variations in the density of the electric current that passes through a given fibre, or group of fibres, or twig of nerve that ramifies the fibres, (but without actual interruption,) according to the law laid down by M. Dubois-Reymond, namely, that a muscle responds by con- traction not only to the interruption of the current, but also to a variation of the current. These labile contractions can, there- fore, be produced when, from the effects of the current, the nerves and muscles have acquired a certain degree of excitability, and if we then give to one or botb electrodes the least move, or by gliding them along a little without actually removing either of them from the skin, the muscle fibres over which the mov- ing electrode approaches go into contraction, while those other fibres of the same muscle, or other muscles that the electrode leaves, at the same time cease to contract. If, now, the button- like electrode, that is covered with wet cloth or wash-leather, be moved along in a wavy or undulating manner over the course of the nerve, then all the muscle fibres depending on that nerve will be affected ; i. e., if they are in a state of sufficiently high excita- bility. Those fibres near by and immediately touched will also be influenced, but in a less degree. On the whole, the working will often appear to be the strongest in the nniscle fibres them- selves. We can produce analogous labile excitement in the 27 *