The nervous conditions or affections requiring the use of the nervous stimulants may be arranged under the following heads.

1. Morbid Excitability of the Nervous Centres

This is a morbid condition, not a deranged action. The patient may possess it, yet, in the absence of any excitant agency, may appear perfectly well. The condition, however, is on the brink of disease, into which the slightest impulse may precipitate the system. It is often the result of a luxurious and easy life, with sedentary habits, and a feeble restraint over the various propensities, moral, sensual, or physical, which belong to our nature. Some, by their original constitution, inherited or accidental, have a tendency to it. Such persons are said to have a nervous temperament. Women, by their very nature, are more subject to it than men; because, having a great additional function to perform, beyond what belongs to the other sex, for the preservation of the species, they require more impressible nervous centres, so that all parts of the double existence may be brought into a due relation, by a ready perception of their mutual wants. On the same principle, to a certain extent, children are more excitable than adults. The rapid growth of their systems requires a quick impressibility of their nervous centres, in order to preserve a proper balance of the functions. Hence, in all these classes, nervous diseases are more common than in others. It is true, that the nervous stimulants have little effect in correcting this morbid excitability; but they may be occasionally used advantageously to guard against positive disorder, under circumstances of necessary exposure. The cure of the condition must depend upon a removal of its causes, and the employment of measures calculated to invigorate without exciting the system.

2. Spasmodic Affections

These are extremely numerous, and, whenever dependent on mere depression or excitement, without active congestion of the nervous centres, may be treated advantageously with the nervous stimulants. These medicines are equally efficient, whether the spasm occupies the voluntary muscles, the involuntary, or those partaking of the character of both.

Of the first, or that seated in the voluntary muscles, we have examples in subsultus tendinum, cramps or painful spasms of particular muscles, and clonic spasms or convulsions, sometimes confined to the muscles of one or a few parts of the body, and sometimes more or less general. In the first and last of these kinds of spasm, the nervous stimulants are more efficient than in the intermediate. This generally depends on an amount of irritation either in the nervous centres or other part, which is in most cases beyond the reach of these medicines. For example, the spasms of tetanus, the external cramps of cholera, and even ordinary cramps in the limbs, are little influenced by the nervous stimulants, given in their proper capacity. Such of them as have narcotic properties are often serviceable, when carried to the point of narcotism.

Among the spasmodic affections of the involuntary muscles are cramps of the stomach and bowels, gall-ducts, ureters, and bladder, and spasm of the bronchial tubes as in asthma, of the oesophagus, and, in women, of the uterus and vagina. There are none of these, when dependent on mere functional disorder of the nervous centres, whether spinal or cere-bral, which may not be benefited by the nervous stimulants. But they are often produced by local causes, and associated with inflammatory conditions, which contraindicate the medicines of this class.

Of spasm in the mixed voluntary and involuntary muscles we have examples in the diaphragm, as in hiccough, which generally yields to the nervous stimulants, and in painful spasm or cramp, which may often be benefited by them, but often also requires more powerful remedies; in the muscles of respiration generally, as in hooping-cough, which is much alleviated, but seldom or never cured by them; and in the muscles of the glottis, as in laryngismus stridulus and catarrhal croup, the former of which is often benefited by them, the latter seldom.

3. Irregular Movements of the Voluntary Muscles, not Spasmodic

Of this kind are general restlessness, jactitation, aimless muscular mo-lions, whimsical gesticulations, imitative or suggestive movements but half voluntary, hysterical laughter, sobbings, facial distortions, hurried respiration, violent coughing, etc., all of which are often happily controlled by these remedies.

4. Disordered Sensation

This is extremely frequent, and of a character more or less amenable to nervous stimulation. Examples of general disorder of this kind are presented in malaise or uneasiness, fidgetiness, weariness, lassitude, and soreness; and of local disorders an infinite variety, as tingling, itching, prickling, etc., in the skin and other parts; neuralgic pains, which may occur almost anywhere; headache, giddiness, dizziness, weight, tension, fulness, etc., of the head; buzzing, roaring, hissing, whizzing, etc., in the ears; sparkling, flashing, perverted colouring, double vision, muscae volitantes, etc., in the eyes; false odours and perverted tastes; feelings of want of breath, weight, tightness, oppression, suffocation, etc., in the chest; constrictive globus hystericus in the throat; and, in the stomach, bowels, and other abdominal and pelvic viscera, numerous and diversified feelings of uneasiness, which are too vague to be described, or to have been named.

5. Diminution or Loss of Muscular Power or Sensation

Dimness of vision, hardness of hearing, loss of articulation, aphonia or more or less complete loss of voice, paralysis of one or more of the voluntary muscles, incontinence of urine and feces, constipation ana tympanites from suspended peristaltic movement, are examples of nervous disorder, which, though frequently dependent on affections quite beyond the influence of the nervous stimulants, are sometimes purely functional, and yield more or less to their influence.

6. Mental Disorder

Under this head may be placed depression or false elation of spirits, hysterical fancies and emotional perversions, brief delusions, hypochondriasis, hysterical insanity, and the delirium of cerebral exhaustion, as in low typhoid fevers and proper delirium tremens. Obstinate wakefulness, untimely drowsiness, lethargy, disturbed sleep, nightmare, uneasiness or whimsical dreaming, somnambulism, long-continued hysterical insensibility, may be placed in the same category.

7. Derangements of the Organic Functions

These embrace every conceivable disorder of every function, whether increase, diminution, or perversion, provided only that it do not result from inflammation or organic disease; for all these functions are more or less under the control of the nervous centres. I shall not pretend to enumerate them; but a brief notice of a few of them may serve to give the student some idea of their nature. In relation to the lungs, there is dyspnoea and asphyxia; to the heart, palpitations and faintness, or positive syncope; to the stomach, nausea, vomiting, eructations, flatulence, loss of appetite, morbid craving, and desire for strange articles of food or medicine; to the bowels, borborygmi, diarrhoea, and constipation; to the kidneys, excessive limpid diuresis; and to all other secretory organs, more or less perversion of their office.

Of the recognized diseases in which the morbid phenomena above noticed occur most frequently, and in greatest diversity, and in which they most readily yield, at least temporarily, to the nervous stimulants, hysteria undoubtedly stands at the head. Probably nervous rheumatism and gout come next in order; and the greater number of the phenomena above mentioned are often nothing more than results of disordered function, arising from influences which, ordinarily producing the inflammatory symptoms of those diseases, cause only nervous disorder when they act upon feeble, anemic, or nervous individuals. I have noticed, however, that the functional disorder in these affections, though occasionally much benefited by this class of remedies, does not yield to them so readily as the analogous affections in hysteria. Chorea, pertussis, spasmodic asthma, nervous cough, hypochondriasis, and delirium tremens are other special diseases in which the nervous stimulants are often indicated, but are generally alone insufficient to effect a cure. Epilepsy and neuralgia are sometimes benefited by them, but very seldom cured. There are, indeed, few diseases which are not occasionally attended, in certain stages of their progress, or in certain associated conditions of the system, with one or more of the symptoms enumerated, and in which the nervous stimulants are not sometimes indicated.

There are various remedial influences which act upon the nervous centres in a manner somewhat analogous to the nervous stimulants, and which, not being properly medicines, must be considered in this place. They may be included under the heads of the emotional and the sensational.