There are, as yet, very considerable differences of opinion among electro-therapeutists as to the principles which should govern us, both in the localization of the effect and the direction of the current. Benedikt, for example, recommends that the current should be directed toward the supposed seat of the mischief. Thus, if we suppose a neuralgia to depend on morbid action within the spinal cord, then we may galvanize the spine, taking care to make the current come out through any vertebra over which we detect tenderness. If we suppose the seat of the disease to be in the nerve-root in the mere ordinary sense of the word, then we apply the positive pole to the vertebra opposite the highest nerve-origin that can be concerned, and we stroke the negative pole down by the side of the spinous processes, some forty times in succession. The proportion of cases of idiopathic neuralgia in which this treatment succeeds is, according to Benedikt, very large. In other cases, he sends the current from the cord to the apparent seat of pain. On the other hand, Althaus[43] tells us that, whether the application be central or peripheral, it is the positive pole, alone, which should be applied to the part which we intend to affect: and that the application of the negative pole in this situation is rather likely to do harm than good, as proving too exciting. Eulenburg, also, says that in general the positive pole should be applied to the seat of the disease, the negative on an indifferent spot, or on the peripheral distribution of the nerve.