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

compelling the molecules, of which a fibre is constituted, so to arrange themselves exactly, that their movements of rotation are accomplished in them all in the same direction, around the same relative axis, in the whole bundle. But of all the influences that are exercised over the native or natural muscular current is the contraction of the muscle itself. This is brought about by nerve irritation; as by the impart- ing to a motor nerve, and that, perhaps, first through a sentient nerve by physical, mechanical, or chemical means, a particular state that is usually manifested by a contraction. To effect this, the most reliable and efficacious of all means is the transmis- sion of an artificial current of electricity through the nerve; and this is modified again most astonishingly by the form of the current, and by the mode of applying it, as well as by the condi- tion not only of the nerve and muscle, but also of the central organs. Consequently, the greatest possible precaution is re- quisite to the correct employment of this agent as a remedy, by influencing, disturbing, and even determining the native muscle and nerve currents that are disordered. As an illustration, it may be stated, that the actual passage of every electric current of induction, through a nerve or muscle, is found to produce a degree of minute tetanic contraction, which may not always be visible to the naked eye, nevertheless is attended at first with a sudden change in the direction of the native current; then there is an oscillation, as manifested by the needle of the gal- vanometer, which then appears to be unable to come to a rest in any position of equilibrium so long as this artificial tetanic state endures. This result, which was first pointed out by M. Matteucci, has been designated by him as the induced contraction. M. Dubois- Reymond appears to have demonstrated that this induced con- traction, which he terms secondary, is only one form of mani- fested variation of intensity that the native muscular current undergoes, and that this deviation is a weaker one. To illus- trate the existence of the muscular current in healthy living men, Reymond plunges all the fingers of both hands respec- tively into two vessels which are filled with salt water, but in-