Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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lower one, are incapable of exciting convulsions, which, however, at once appear as soon as the electrodes of the lower circuit advance a little on the muscle. Then, if the direction of the current is reversed, we will find it requires a greater difference in the strength of the two circuits to render the opening and closure of the lower one ineffective ; therefore, where weak cur- rents are employed, the up-running current from both batteries will prove the most favorable. Dr. Eckhard is evidently mostly interested and mainly occupied in discovering the differences obtained from the different stream directions, and says he finds the up-running current to prove the most paralyzing. But he himself as evidently contradicts this statement in all his subse- quent deductions. From such unfortunate statements has arisen a very great prejudice in the minds of medical practitioners against employing the primary steady current of galvanism with occasional interruptions or changes in density. Another proposition of Dr. Eckhard's is, " Every constant current that flows through the motory nerves occasions on the traversed part, and that lying above the positive electrode, a diminution of excitability, while, on the other hand, the excita- bility increases in the part situated under and beyond the negative electrode. Moreover, that the excitability is always increased underneath the negative electrode of the circuit ivhen it is so situated as to work at the upper end of the nerve in a downward direction." Dr. Hcidenhain subjected these opinions to a series of rigid trials, and concludes, without however being aware of Marianini's results, that a muscle, or group of muscles, which, either from straining, extreme heat, or teasing by abusive induction shocks, (or by any other means,) has been deprived of its excitability, regains its power of contracting by the aid of the steady con- tinuous galvanic current, and that more rapidly by means of the up-running current than when its course is downwards. Dr. Pfluger, on the other side, subjected others of M.Echard's experiments to trials, and he concludes that the stream fluc- tuations of a constant current do not produce equal shorten- ing of the muscles, or portions of the muscles, through the