Other drugs act as specific sialagogues upon the terminations of the portio dura in the salivary glands, or on the cells themselves. Such are Jaborandi, and its active principle Pilocarpin, Tobacco, Physostigma, Mercury and Iodine, and the indirect emetics Antimony and Ipecacuanha.

Opposed to these measures are the antisialagogues, equally at our service, although but rarely employed. Such are insipid or nauseous articles of food or medicine, with which may be classed depressing emotions and other nervous influences; dilute alkaline or soapy substances acting locally, such as Potash, Soda, and Lime; and certain articles of the first importance in the materia medica which act upon the secreting nerves, and may, therefore, be called specific antisialagogues. The type of these is Belladonna (Atropia), with Hyoscyamus, and Stramonium (Hyoscyamia). Tobacco in excess has the same effect, as well as Opium.

If the natural secretion fail, certain substitutes for the mucus may be employed, which are called demulcents {demulcere, to soothe), as they sheathe the mouth, tongue, and fauces with a protective coating. Such are simple drinks, especially tepid water, toast-water, water and milk; mucilaginous preparations, in a fluid or solid form, including barley-water, gruel, and linseed tea; various preparations of gelatine and isinglass; lozenges made with gums ; preparations of starch, eggs, honey, figs, and bread; palatable oils; syrups; and ice.

4. The excretions of the mouth can also be influenced by means of substances which are thrown out of the system by this channel, such as Iodine, Lead, and Mercury. The therapeutist can hardly be said to avail himself of this means of acting on the mouth.

5. The mastication and insalivation of the food can also be regulated, on the one hand by insuring time and care in the process of eating, and on the other hand by ordering such a diet as is entirely fluid, or may be thoroughly triturated and exposed to the juices of the mouth.

III. Pathological Relations

As has been already suggested, the pathological relations of the mouth and the first part of the digestive process, are of less interest in themselves, for our present purpose, than from their bearing upon digestion in the stomach, and the farther progress of the food.

1. We discover in the food the chief cause of all digestive disorders, whether it be unsuitable in quality, excessive in quantity, or taken at over frequent or irregular times.

2. Loss of the sense of taste is familiar in fever, the result being further arrest of the salivary flow, and interference with relish and appetite, always a serious matter in such cases. In this connection must be mentioned the unfortunate tastes of most drugs, the difficulty of their administration, and the degree to which they interfere with the appetite.

3. Disorders of the secretions of the mouth include chiefly disturbances of the quantity of saliva and mucus. The saliva is probably deficient in some cases of long standing indigestion; and it is markedly wanting in acute febrile conditions, causing dryness of the tongue and mouth, thirst, loss of relish as we have just seen, and inability to swallow, the morsel being rolled hopelessly about the mouth. A somewhat similar condition may be induced by depressing emotions, such as fear or grief ; or by certain medicinal or dietetic substances, including Belladonna, Opium, and Alcohol. Excessive secretion of saliva and mucus ("salivation") was very frequent in the days when Mercury was regularly administered until the "gums were touched"; and is still occasionally seen from the same cause, as the result chiefly of accident or idiosyncrasy; or as the effect of Iodine and Iodide of Potassium, under similar circumstances. A reflex salivary flow of a very interesting kind occurs at the commencement of vomiting, and in some cases of gastrointestinal disorder, constituting one form of "pyrosis" or "water-brash." In other cases salivation is produced by disease of the nervous centres.

4. Derangements of the excretions of the mouth are among the causes of the "bad taste" and unpleasant odour of the breath, connected with digestive derangements; the other principal causes of the same being decomposition in the mouth, or excretion by the respiratory passages. Some drugs already mentioned have the same effect, such as Mercury, Iodine. Bromine, and Lead; and the prevention of this unpleasant action may be a difficult task.

5. Second only to the food itself as a frequent cause of indigestion is the imperfect manner in which the mechanical processes in the mouth are performed, the solids being imperfectly masticated and insufficiently insalivated from hasty or careless eating, or from disease or actual loss of the teeth.

IV. Natural Recovery

We have next to enquire, whether natural recovery, as defined by us in the first chapter, ever occurs in connection with the mouth and its functions. Observation places this beyond doubt, in all the classes of disorder to which we have just referred. The sense of taste is restored after fever has gone. The secretions which have been deranged by the same cause, or by Atropia, Mercury, or Jaborandi, return to the normal quantity and quality when the disturbing influence is spent or has been removed. The excretions again become "sweet" when the substance that disordered them has been completely thrown out. The teeth present side by side with decay a process of repair, which frequently counteracts it.

There is, however, a limit to recovery in the mouth, as elsewhere. The teeth decay and fall out; and the other tissues may become involved in serious or hopeless disease. Even then, as we shall presently see, rational treatment is not impossible.

V. Therapeutics

The rational treatment of diseases originating in the mouth is but the scientific application of the knowledge arranged under the previous four heads, respecting its physiology, the forces acting on the mouth which are at our command, the causes and phenomena of its derangements, and the occurrence and limits of natural recovery.

1. The food must always receive most careful supervision, not only in cases where it has been bad, improperly taken, or imperfectly masticated, but in every instance of disorder of digestion from whatever cause, in the mouth or other part of the alimentary canal. The details of dietetic treatment must be learned from other works.

2. The disorders of the sensory apparatus of the mouth very rarely call for treatment, but we have constant occasion to avail ourselves of our influence over the nerves of taste for the purpose of relieving derangements of the secretions. Thus deficiency of saliva, and the distressing thirst and loss of relish which attend it in fever, may be relieved either through the nerves of taste, or more directly by means of acids in the form of drinks, such as water acidulated with the Mineral Acids, Vinegar and water, Carbonic Acid in effervescing drinks, Cream of Tartar, Lemon Juice in various combinations, and acid fruits, if not otherwise unsafe, including the Tamarind of the pharmacopoeia, grapes, and oranges. Failing or instead of these, ice, sips of water, and some of the demulcents already enumerated may he given. When the deficiency of saliva, the dryness of the mouth, and the lack of relish are less urgent hut more persistent, as in chronic dyspepsia, we adopt more pleasing means of stimulation. We have recourse to aromatic, hitter, spirituous, and pungent articles. We order food specially flavoured or made otherwise agreeable to the palate by artistic cookery. When the appetite flags after severe illness or in exhaustion from other causes, we recommend the patient to stimulate his palate with a little wholesome wine, which is at once acid, aromatic, and spirituous. We rouse the nerves of taste and the secreting glands by simple or aromatic hitters in acid or alcoholic combinations before or during meals, or pungent and acid condiments, such as mustard, pepper, and pickles.

3. When it is desired to rouse the gustatory and secreting functions of the mouth independently of digestion, e.g. in cases of paralysis of the mouth, and in the chronic thirst of Blight's disease and diabetes, such substances as Pyrethrum, Tobacco, and small doses of Pilocarpin are indicated. The dryness of the mouth and throat caused by Atropia and Hyoscyamia may require the suspension of the drug, or Jaborandi may be prescribed with it unless contra-indicated. On the other hand, salivation produced by drugs must be arrested by removal of the cause, such as Mercury, or the exhibition of Belladonna.

4. The treatment of unpleasant excretions from the mouth is rationally carried out by removing their cause, especially disorder of the stomach and bowels; deodorising the breath; or imparting to it an artificial odour.

5. Defects in the mechanical apparatus of the mouth, especially the teeth, have, as a rule, advanced beyond the limits of functional treatment. Even then treatment is not only possible, but dental surgery is one of the most rational and successful branches of local therapeutics. Short of this, much can be done by ordering food in a soft or fluid form, and directing that time and care be spent by the patient over the process of masticating, tasting, and insalivating every morsel.

Lastly, a discussion of the action of drugs upon the mouth introduces us naturally to the therapeutics of the next stage of the digestive process-in the stomach. The substances which stimulate the nerves of taste are constantly employed, as we shall see, to produce reflex activity of the gastric functions; and the thorough insalivation with the alkaline juices of the mouth, for which they also provide, may be used as a powerful means of increasing the acid secretionSynopsis of Remedies which act upon the Mouth.