The view which I am strongly convinced alone explains the beneficial action of blisters is that which supposes them to act as true stimulants of nerve-function. In order that this effect shall be produced, it will be necessary that the skin-irritation be either produced at some distance from the seat of the greatest pain, or that, if applied in that spot, it shall be comparatively mild in degree. And accordingly, I have been led, in my observations to apply the blister at some distance from the focus of pain. An indifferent point, however, will not do--there must be an intelligible channel of nervous communication between the irritated portion of skin and the painful nerve. This object is accomplished by placing the blister as close as may be to the intervertebral foramen from which the painful nerve issues; the effect of this is probably a stimulation of the superficial posterior branches, which is carried inward to the central nucleus of the nerve. I must say that the results which I have derived from this plan of treatment have been far more satisfactory than those which I used to obtain when I habitually applied the vesication as near as might be to the focus of peripheral pain; and I think that this result tallies well with the idea that the essential mischief in neuralgia consists in an enfeebled vitality of the central end of the posterior root. An exceedingly interesting confirmation of this idea as to its _modus operandi_ has been afforded me by the fact that not merely neuralgic pain, but also trophic and inflammatory complications attending it, have been sensibly relieved, in several cases that I have seen, by this mode of reflex stimulation. This has been particularly the case in herpes zoster, where the process of inflammation and vesiculation has been very promptly checked by the application of a tolerably powerful blister by the side of the spine at the proper level; and I am gratified to mention that Dr. J. K. Spender, of Bath, pointed out this fact[39] at a time when he had only seen my statement that the pain could be relieved in this way. In the case of the trigeminus, the same kind of reflex stimulation is most effectively obtained by applying the blister over the branches of the cervico-occipital, at the nape of the neck; and it is remarkable what powerful effects are sometimes thus produced, even in cases that wear the most unpromising aspect. For example, in the desperate epileptiform tic of old age, I have more than once seen a complete cessation of suffering, which lasted for a very long time--so long, in fact, as to make me hope against hope that it might never return. I do not now entertain any such expectations from this remedy; still, its value is very great.