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

Another important fact, that is obtained by him, both from these trials and from the treatment of many cases, which is a gain for therapeutics, is this — that a constant primary current, of a supportable and reasonable strength, directed through the nerve trunks and muscle fibres by means of metallic electrodes with wet coverings of buckskin or cloth, applied to the skin of a healthy person, is far from producing any sort or kind of "palsying" influence whatever; but, on the other hand, the increased excitability of the affected parts from the working of the current becomes perceivable in the sentient nerves, as shown by increasing pain ; and under favorable circumstances, is shown also in the motory nerves by tonic contractions. If, therefore, it is almost impossible to derive, by means of the constant current through wet covered metallic electrodes, any other than the more vigorous actions of the muscles through nerves, it is clear that a doivn-toning or paralyzing effect is only to be expected or obtained under the conditions by which M. Matteucci tried to ac- complish it, viz., by means of wet strips of linen used as elec- trodes to let on the current in the utmost gentle and gradual manner possible, and to maintain it long, and then to take it off in the same slow and cautious way, so as to avoid produ- cing any twitchings, or tonic contractions, by avoiding the least possible approach to interruptions, or variation in the density of the in-working constant current. Here I must also mention that we should take care not to ascribe the absence of sensation, absence of closing twitching, or absence of tonic contraction, to the necessary want of ac- tion in the current; and therefore it is of paramount impor- tance for those employing the constant galvanic currents for therapeutic purposes to always include a galvanometer, or some kind of electrometer, as the galvanoscope, in the same circuit, so as to indicate some, but, better still, the precise degree of activity of the current; or employ Garratt's graduated battery. As a general rule, I think the comparative excitability of nerve trunks, as uniformly shown by pain or contraction, appears greater the nearer the excited portion of the nerve lies to the brain. This holds good not only as regards single nerves, but it