In electrization of the central organs of the nervous system, the Voltaic current is alone used, and in its application to the brain, the sympathetic nerves, or the organs of the senses, especial circumspection must be employed. As a general rule it should not be had recourse to when central excitement is contra-indicated, and in _all cases_ the minimum dose should be commenced with, and the application discontinued upon the occurrence of giddiness, nausea, or cerebral symptoms. With these precautions the brain may be electrized by well-moistened sponges applied to each mastoid process, to each temple, or to the frontal and occipital protuberances. The sponges must be held immovable. To galvanize the superior cervical ganglion of the sympathetic, one electrode of small size must be deeply pressed into the auriculo-maxillary fossa, and the other with a good-sized sponge applied over the sixth or seventh cervical vertebra, or to the manubrium sterni, close to the border of the sterno-mastoid. The spinal cord may be electrized by keeping one sponge, usually the positive, stationary, and moving the other up and down by the sides of the vertebræ, or one pole may be applied to the spine, and the other held to a nerve or muscle. The retina by a moistened conductor to the closed eye, and the second to the temple or to the mastoid process of the same side. The auditory nerve by one conductor tipped with sponge and inserted to the bottom of the meatus, the second being held in the hand of the opposite side; or the meatus may be filled with tepid water, and a metallic wire traversing the axis of a vulcanite tube may be immersed in the water, the second conductor being a well-moistened sponge to the nape of the neck. Direct application to the ocular muscles or to the conjunctiva is usually inadmissible, but one pole may be placed over the facial nerve below the ear, and the other applied to the closed eyelid, or the operator may use the forefinger of his right hand, covered by a finger-stall of wet linen as an electrode, passing the current through his own body by holding a moistened sponge from one pole in his left hand, the conductor from the second pole being similarly held in one of the hands of the patient. This application is not only convenient, but it is calculated to allay the fears of a sensitive patient: or a pointed conductor, covered with wet leather, may be connected with one pole, and its point held immovable and firmly pressed down upon the orbital margin, as near as possible to the position of the muscle it is desired to excite, while the patient touches at intervals the sponge from the second pole held by its insulating handle in the operator’s disengaged hand. [SN: Electrolysis Needles.]