Additional experiments on the excitability of paralysed and healthy limbs by the galvanic current / by R. B. Todd, M.D., F.R.S. (Physician to King's College Hospital).

  • Todd, R. B.
Date:
1853
Catalogue details

Licence: Public Domain Mark

Credit: Additional experiments on the excitability of paralysed and healthy limbs by the galvanic current / by R. B. Todd, M.D., F.R.S. (Physician to King's College Hospital). Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    6/26 (page 4)
    where it had been inverse, and vice versd, the contractions always became more intense when the current was made to take the direct course. In short, these experiments showed that the physiological effects of the coil machine and of the magneto-electric machine were precisely the same as those of the galvanic trough. Both these instruments are capable of producing contractions of the utmost intensity, but they are also ex- tremely manageable. The coil machine readily permits its intensity to be regulated, for by varying the quantity of the inducteous material its power may be made to range from almost zero up to such a degree as to excite violent tetanic convulsions and the most horrible pain. I must leave it to others to explain how, under similar circumstances and in the same individual, opposite physio- logical effects may be produced with the galvanic trough and with the coil machine. Perhaps in the experiments which yielded these opposite results, the importance of attending to the direction of the current was overlooked. The facts above detailed have a very important signifi- cance. They denote, not only that in comparing the ex- citability of one limb under the influence of the galvanic current with that of its fellow, due care must be taken to compare them under similar states of galvanic influence, —i. e., with the current taking the same direction in each,— but likewise that in exciting contractions the galvanic current acts primarily upon the nerves, and through them upon the muscles. This latter conclusion, to which I had already been led by the facts and reasonings contained in my former paper on this subject, receives strong confirmation from other circumstances. 1. The galvanic current, when applied directly to a muscle, excites it to contract with just the same intensity, whatever direction it may take. 2. If the nerves be carefully removed from the limbs of an animal just killed, the galvanic current will excite con- tractions on both sides, nor can any difference be observed