On the electrical excitability of the skin / by S. Tschiriew and A. de Watteville.

  • Chiriaev, Sergei Ivanovich, 1850-1919.
Date:
1879
Catalogue details

Licence: Public Domain Mark

Credit: On the electrical excitability of the skin / by S. Tschiriew and A. de Watteville. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    tlie variable thickness of the epidermis. Yet, in order to bo able to measure the excitability, not of the collective nervous elements of the skin, but of the cutaneous nerves themselves, we must be able to eliminate the sources of variation arising from the structural differences of the nervous supply in different parts of the skin. We have, it is true, no direct anatomical demonstration of such differences; but physiological observations, such as the measurements with E. H. -Weber’s compasses, allow us to sup- pose that the number of nervous endings in a unit of cutaneous surface varies in different parts of the body. If this suppo- sition be true, it necessarily follows that an ‘ electrode of the same surface applied to different parts of the body ought to produce excitations of various strengths merely on account of the variable richness of the skin in nerve-endings. The way to eliminate this source of error consists in always exciting the skin at the same number of points by means of a special form of electrode. The simplest would be a pointed electrode which would eliminate the influence of a variable number of excitations by reducing this number to a minimum; but its sharpness would make an accurate estimation of the minimal electrical excitation difficult. The followiusr form of O electrode, however, satisfies the present condition sufficiently well: It consists in a small cylindrical bundle of well insu- lated wires; and it is not difficult to understand the im- portant difference between the efiects of such an electrode and those of one in the shape of a solid cylinder of the same diameter. Tlie figure makes this diflerence evident. The excitation produced by B will be stronger than that prodnced bv A J'. 2