of Larynx.

second moist rheophore is applied externally. The Electrization muscles of the pharynx may be electrized with a similar director, but this is a proceding requiring

FIG. 42.

Dr. Morell Mackenzie's laryngeal rheophore.

great care, on account of the contiguity of the glosso-pharnygeal, pneumogastric, and recurrent

nerves.

of Male

5. Electrization of the male genital organs.-Moist Electrization rheophores are placed upon the scrotum over the Genitals. testicle or the epididymis. If it be desired to excite the vesiculæ seminales, the bowel is first emptied, the rectal rheophore is then introduced and so directed that its olive-shaped termination may be brought into relation with the vesiculæ. For this purpose it is sufficient to move the rheophore from right to left and vice versa. A powerful current will penetrate the intestine and reach the vesiculæ, exciting them energetically. The circuit is completed by a second rheophore placed on an unsensitive part of the body.

ELECTRIZATION OF THE ORGANS OF THE SENSES.

of the Organs

Electric excitation of the senses of sight, hearing, Electrization smell, and taste should be performed with extreme of the Senses. care, from its liability to re-act acutely upon the

brain. It should never be had recourse to in cases
in which central excitement must be avoided, and
in all cases the minimum dose should be com-
menced with. These cautions are
These cautions are especially impor-

tant with the voltaic current.

Electrization of Retina.

BADOUREAU.

Rheophore introduced into the auditory meatus.

Electrization of the retina.-Voltaism has the distinctive property of re-acting acutely upon the retina, producing sensations of flashes of light when

*A. The concha. B. Meatus auditorius externus, in which the rheophore, insulated by a tube of ivory, E, is inserted. The lower half of the meatus is filled with tepid water. F. The tympanum. G. Eustachian tube. H. Labyrinth and auditory nerve. 1. Membrana tympani attached to the malleus. J. Laxator tympani externus. K. Tensor tympani. L. Laxator tympani.

the conductors are applied to any part of the face. A moistened rheophore is applied to the closed eye and a second to any part of the face.

Electrization of the auditory nerve.-The external Electrization of Auditory auditory meatus is filled with tepid water, and a Nerve. metallic rheophore, insulated by ivory or vulcanite, is placed in it, and the circuit completed by a moist rheophore on the neck. The operation is shown in fig. 43.

of Olfactory

Electrization of the olfactory nerves.-A moist Electrization rheophore is placed over the back of the neck, and Nerves. a metal sound, insulated except at its extremity, is moved over all points of the nasal mucous membrane.

of Nerves of

Electrization of the nerves of taste.-A rheophore Electrization is placed over the back of the neck, and a second Taste. is moved over the base and borders of the tongue.

CHAPTER III.

Electro-Diagnosis.

ELECTRICITY AS AN AID TO DIAGNOSIS.

ELECTRICITY will assist us in diagnosis only in those conditions in which there is altered muscular contractility, or cutaneous or muscular sensibility, or both. In the normal and healthy state of this tissue muscles and nerves respond to the electric stimulus whatever variety of electricity is employed, but in disease this reaction may be increased or diminished or altogether absent. The irritability of a muscle is tested by ascertaining the lowest power which will cause its contraction. The procedure is as follows :-Assume the case for example to be one of ordinary hemiplegia, say of the left side. Take in one hand the two rheophores of a Faradic instrument in action and apply them to one of the Contractility. muscles-the extensor communis digitorum will do— of the right or healthy side; having found the lowest power to which the muscle responds, apply the rheophores to the same points of the same muscle on the diseased side, and note whether there is contraction; if there is, decrease the power of the current, and if contraction still occurs there is increased irritability, or vice versa, as the case may be. In testing with Test of Voltao- the voltaic current keep one electrode stationary and Contractility.

Test of Farado

interrupt the current by gliding the second over Precautions in mode of applithe muscle or repeatedly lifting and re-applying it. cation. It is essential that on both sides there should be exact similarity in the application, and that the electrodes should be placed on identical points of the muscle; and this is especially important with the voltaic current, for healthy muscles answer to it more readily when it flows down the limb than when it flows up, and consequently a reversal of the poles will influence the result.* In testing a case of paraplegia where there is equal disease on both sides, you must be guided by a knowledge of the strength of current usually required to bring about contraction. As a general rule, unless a current that causes energetic and painful action in the Strength of muscles of the ball of the thumb produce some contraction the irritability is impaired. In either diagnostic or therapeutic electrization the operator should never use electricity upon a patient without first testing it upon his own hand, and if about to apply it to the face, upon his own face. This is a most important rule, never to be neglected. There

is no certain means of securing that the strength of either a voltaic or faradic current shall not have

* The current that passes from a nerve centre to the periphery, that is, from the positive electrode placed nearer to the centre, to the negative, placed farther from it, is called a "direct" or descending current. The reverse current is the "indirect" or ascending. Healthy nerve and muscle respond to a lower power when the current is descending than when it is ascending.

Rule for

Current.