Electricity in its relations to practical medicine / by Moritz Meyer.

  • Meyer, Moritz, 1821-1893.
Date:
1874, ©1869
Catalogue details

Licence: Public Domain Mark

Credit: Electricity in its relations to practical medicine / by Moritz Meyer. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    ings of the circuit follow one another slowly, clonic or inter- mitting spasms ensue, if they follow one another rapidly, in such manner that the new contraction begins before the preceding has ceased, rigid or tonic spasm results. If this condition has continued too long, or if the nerve originally possessed insufficient irritability, intermitting spasms will ensue. In the vigorous muscle of a frog, in the beginning at least, tonic spasms may appear, if even there are not more than two strokes in a second; a less number produce clonic spasms from the first. The phenomenon, that a muscle contracts only at the closing and opening of the circuit, or only at the moment when the density of the current increases from nought to a certain degree, or descends again from this degree, but not between these two points, when the circuit remains closed and the density remains unchanged, finds its explanation in the fact that the contractions depend on the changing of the density of the current with the greatest possible rapidity. For this reason Du Bois-Reymond gave the following as the first law of the electric-irritation experiments:' It is not the absolute grade of the current density at each mo- ment to which the motor nerve, by a contraction of its muscle, responds, but to the change that takes place in the grade of density from one moment to another. Thus the power of producing the contractions that follow these changes is increased the more rapid the changes are when alike in degree, or the greater they are in a given length of time. If we have, therefore, a given quantity of electricity, and conduct it in a current of unvarying power through a muscle, the current intensity remains the same from the closing of the circuit to the opening; consequently, during this time, no contractions take place. The same quantity, conducted in an interrupted current, will produce tonic or clonic spasms, according as the interruptions follow one an-