6 LOCALIZED ELECTRIZATION. 



be limited to the skin. Sucli is the tension obtained from an 

 electric machine of medium power: which is hardly enough to 

 produce contraction of the superficial muscles, especially if the 

 cellular tissue be rather abundant ; and, if produced, the contrac- 

 tions will be incomplete. 



Although it is possible to confine the action of static electricity 

 to the skin, it is not possible to concentrate its power upon the 

 muscular tissue or upon the sub-cutaneous nerves. In fact, the 

 superficial action of this form of electricity is inseparable from 

 its deep action. In the latter the electric recomposition is still 

 effected at the epidermic surface, and produces a cutaneous sensa- 

 tion that obscures the muscular. 



The tension obtained by means of a Leyden jar enables the 

 current to penetrate through a considerable thickness of tissue. 

 Thus the current from the jar is sufficient to produce energetic 

 muscular contraction ; but however feeble may be the tension, so 

 long as it can be measured by Lane's electrometer, it always 

 produces a shock, that is to say, a contraction and a sensation 

 which extends beyond the point excited, and which is felt most 

 acutely in the nervous centres. 



If the exciter be placed over a nervous trunk, the sensation is 

 like that produced by a severe contusion of the nerve, and is fol- 

 lowed by a numbness that extends almost to the ultimate rami- 

 fications. With a sufficient degree of tension, acting either upon 

 a nerve or upon muscular tissue, the shock is so strong that 

 the whole limb, or even the whole body, seems as if struck by 

 lightning. 



At the spot at which a Leyden jar is discharged, the skin 

 ffraduallv loses colour over an area of two or three centimetres in 



to •' 



radius, and becomes of a dull white in a few seconds. The ner- 

 vous papillae stand erect upon the blanched surface, which is also 

 somewhat lowered in temperature. The person on whom the 

 experiment is tried sometimes experiences a feeling of numbness. 

 Analogous phenomena appear to take place in the muscular tissue 

 subjacent to the portion of skin that is acted upon. I have had 

 occasion to make an electric discharge upon the surface of a 

 denuded muscle, and this muscle lost somewhat of its colour, over 

 a small space, for some time. The cutaneous local phenomena 

 last generally from twenty to thirty minutes ; and once, in a 

 delicate person, I saw them continue for three-quarters of an hour. 

 After this time, the blanched spot passes, in a few minutes, from a 

 dull white to an erythematous redness, and undergoes an elevation 

 of temperature appreciable by the thermometer, and sometimes by 

 the sensations of the patient. 



