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

manner, but the current must be running up in one while it is running down in the other: now, if these are alternately changed from hour to hour, — i. e., simply reverse the direction of the current, — each of them may be put in the same condition in which the other was the hour before ; and these alternations can be proceeded with for a whole day, or until the excitability grad- ually decreases away. Again: if both arms of a person are exposed to a powerful current, and for a long time, — say half an hour or so, — there will be experienced, in the one in which the current runs up, a feeling of increased mobility; while in the other, where the current runs down, there will be a sensation of heaviness or lameness felt. M. Ritter afterwards corrected these propositions by saying that the exaltation caused by the up-running current does not always appear, but only now and then, as when weak currents are employed, but never when strong currents are used; and after employing a powerful cur- rent for a long time in either direction, there will be produced a depressing influence — i. e., as a general thing, make the excita- bility of a muscle or muscle-nerve thus traversed for a long time to decrease faster than would take place in the already dead frog if left to itself. It must be borne in mind that the above statements, and also the corrections, all date from a time when M. Volta had already published his observations on the alternated actions of the cur- rent, and which he had reached by quite another process. These facts I record because "the alternations of Volta" and "the alternatives of Ritter " are so frequently referred to by the older writers in this department of medical literature. Soon after Galvani's classical experiment (see page 72) had been made known, Dr. Yolta was the first to notice that the electro-muscular contractions take place, if only a portion of the nerve is alone enclosed in the circuit, not transversely, but teng-thivise,&nd that without touching the muscles with the elec- trodes, or even including them between the poles of the circuit. This led to a flood of trials, which were immediately instituted by Volta, Ritter, Pfaff,* Lehot, Humboldt, Valli, and Galvani; * TJber thierische Electricital und Reizbarkeit, Leipzig, 1795.