arsenic; the paroxysms will last a certain time, and the fever will run a certain course, or will leave behind it the permanent marks of cachexia or diathesis.

But the salient fact remains that the paroxysms of ague are to a most remarkable degree under the control of quinine, or arsenic, or other remedies. What is the effect of those remedies? It is an alterative effect, it is to break the habit. If quinine is a "febrifuge," or hostile to the life of living organisms, arsenic certainly is not; and arsenic, as the "tasteless ague-drop," was of the greatest service in ague long before quinine began to be extracted from bark, and was a better remedy than bark itself. Not only so, but in the experience of Annesley, although bark is the grand remedy of fevers in India during the cold season, yet it fails in the rainy reason, in which calomel and antimony are alone useful.*

Taking one remedy for ague with another, we shall conclude that the cure is not by way of killing any hypothetical ferment or organism, but that it is by way of breaking the morbid habit, as Watson says, "by strong impressions made upon the nervous system." As for Professor Binz's statement, "that experimental researches have failed to demonstrate the presence of any such influence of quinine upon the nervous system as it has been supposed to possess,” all that one can say is, so much the worse for experimental researches. Everyone knows that a continued use of quinine in clinical practice makes noises in the

1 A. T. Thomson's Materia Medica,' 452.

ears, or even deafness, or mental confusion; and these, no doubt, are nervous symptoms. If the "influence upon the nervous system which it has been supposed to possess," refer to the much sought proof that quinine lowers the temperature, then the objection is merely irrelevant. It is not by lowering the temperature that quinine cures ague, but by breaking the heat-regulating centre of its periodical habit. As Watson says: 66 This habit of paroxysmal recurrence may be broken by strong impressions made upon the nervous system; and the cure of one paroxysm is often the cure of the disease."

The evidence that the action of quinine in ague is an anti-periodic or habit-breaking action is not only in the fact that its equivalent remedies or drugs in that respect (arsenic, calomel and antimony, change of air and the like) are the most conspicuous members of the old group of alteratives, but also in the fact that quinine itself will often break a habit which is not at all febrile or on any conceivable theory the result of an infective virus. In a case of Sir Benjamin Brodie's, a gentleman who had been long in the tropics became subject to stricture of the urethra of a spasmodic nature, which recurred every other midnight and continued until five or six in the morning. The recurrences were stopped, or the disease was cured, by large doses of quinine at short intervals.

But that kind of alterative action brings me to the second part of this chapter, namely, neuralgias as morbid habits curable by alterative remedies.

Neuralgia.

In neuralgias, as in all other persistent conditions, the first question is whether there be not some abiding cause for the pain, and, in particular, whether there be not some local source of irritation, such as a bad tooth. Such primary or initiating causes of neuralgia are notoriously difficult to discover. Many patients with face-ache are sent to the dentist to have the teeth "looked to," when the teeth are all quiet enough, and there is absolutely no reason to arraign them or to set a dentist to work at them. Face-ache, where it is referable to the teeth at all, is more likely to be a reminiscence of dental irritation long past, than of any morbid condition of teeth still in progress.

In saying this, there is no wish to deny that neuralgias have been cured by pulling out or stopping decayed teeth. But as a general rule, dental caries or periostitis of the fang, or whatever other morbid condition the dental tissues may be subject to, will produce toothache and not neuralgia. Toothache is local, neuralgia is more paroxysmal and pervading; toothache is primary, neuralgia is subsequent; toothache is the reality, neuralgia is the surviving memory. These considerations, it seems to me, are a necessary supplement to the familiar doctrine that the teeth are to blame for much of facial neuralgia, and that the patient requires the dentist's services more than the physician's. To illustrate this view of facial pains

remembered and recalled, I shall relate a case where there was no ambiguity from any supposed implication of the teeth.

The sufferer in this case was a Cambridge mathematician of repute, who may be trusted to have rightly inferred the sequences of cause and effect. Having accidentally struck his forehead just over the eyebrow, against the edge of the mantlepiece, he felt the pain of the blow as usual at the time, and just as naturally soon forgot it. Several weeks afterwards he had an acute attack of neuralgia all over that side of the face; and from some indications of a subtle nature best known to himself, he was led to connect the neuralgia with the contusion of the eyebrow, which had evidently been severe enough to make some impression on his memory. He had never had neuralgia before nor did any explanation of the paroxysmal attack seem so ready to hand as the antecedent supra-orbital injury. The supra-orbital twig of trigeminus had been touched by the blow; it had transmitted impressions to the centre which had not only been felt as painful at the time, but had been stored up

in the chambers of unconscious memory. After an interval, but upon what provocation one knows not, the whole trigeminus of that side of the face becomes the seat of paroxysms of pain, shooting as if from the trunk of the nerve along the several branches, ophthalmic, infra-orbital, and inferior maxillary. It is difficult to regard that particular case of facial neuralgia otherwise than as one of memory. The memory, it is

true, ranges more widely than the reality; also it is paroxysmal like the gusts of a storm. It is as if the original pain had multiplied a thousandfold by brooding upon itself.

There are doubtless many cases like that in the experience of practitioners. I shall mention briefly one other, giving the sequence of events as they were related by the patient, a highly observant man. He is now the victim of periodical sciatica, in which the pain shoots from the hip down every nerve of his thigh and leg. He traces it all to the time, many years before, when he used to sit on a high stool at a desk, not far from a door which was constantly opening and shutting, and admitting currents of cold air. The constantly recurring draughts struck the outer side of the foot, where it was exposed between the shoe and the drawn-up trouser.

Taking this to be the true sequence of events—and the narrative was not inspired by any theory-the external saphenous nerve must have transmitted many slight impressions, which were stored up, to discharge themselves afterwards with thousandfold intensity of pain along every branch of the great sciatic.

If such after-effects as these had been motor and not sensory, they might have been classed among those deferred reflex liabilities of which the paroxysms of whooping-cough have been taken to be one instance, and of which an attack of tetanus, following a wound or other local irritation of a nerve-twig, would be another.