foreign bodies from the nasal cavities, when they are termed sternutatories.

c. To the mucous membrane of the mouth and throat, medicines are applied almost exclusively for local purposes. When in solution, they are termed gargarismata or gargles. Powders are introduced by insufflation.

d. To the Eustachian tubes, washes are applied in local affections.

e. On the aërial or tracheo-bronchial membrane, medicines produce a very decided influence, both local and general. Liquid substances are introduced into the air passages by means of a sponge or syringe, in the treatment of chronic inflammations of the larynx. Various substances are inhaled with advantage in phthisis, chronic bronchitis and laryngitis, asthma, &c., while the most powerful effects are produced on the system by the absorption of ethereal vapours and gases through the pulmonary surface.

Within the last few years, liquids have been introduced into the air-passages, for the treatment of diseases of the respiratory organs, in the form of a fine spray. This mode of application, termed the pulverization, nebulization, or atomiza

tion of fluids, has proved very valuable, particularly in the relief of throat affections. Various instruments have been resorted to in the atomization of liquids. The hand-ball atom

Victration cixperiments.

te 406

izer, which is usually employed, consists of two glass tubes, with capillary openings, placed at right angles to each other, the vertical tube being dipped in a bottle containing the fluid. to be atomized, while at the other end it is close to and about opposite to the centre of a capillary opening in the horizontal tube. This connects with an elastic tube, intercepted by two elastic balls, one in the middle, the other, which is furnished with the valves, at the end of the tube. The upper ball acts as a reservoir, into which a current of air is forced from the lower ball by pressure with the hand. The air in the vertical glass tube being rarified, the liquid rises to the capillary opening, and is their pulverized by the current of air from the horizontal tube. The atomizer is used also to produce local anæsthesia, and as a deodorizer.

As modified by Winterich, the spray can be readily gener

ated within various parts of the body, as the back of the throat, nostril, meatus of the ear, &c. Instead of air, steam has been substituted as the forcing power in the apparatus known as Siégle's. In this instrument, as modified by Da

Fig. 3.

Costa, inhalation can be practised without fatigue or assistance, and the warmth of the spray is also an advantage in many diseases of the respiratory organs.

f. The gastro-intestinal mucous membrane, of all parts of

the body, is most employed for the exhibition of medicines. The stomach, from its great susceptibility, its active absorbing power, and the numerous relations which it has with almost every part of the body, is the chief recipient of medicinal agents. The rectum is, however, also frequently employed for various purposes, as to relieve disease of this or of neighbouring organs, to occasion revulsion, to produce alvine evacuations, to destroy ascarides, and when for any reason it is desirable to spare the stomach.

It is usually recommended, that the dose of medicines, introduced into the rectum for constitutional effects, should be two or three times greater than when taken into the stomach. In the case of active, soluble medicines, however, especially narcotics, it is most prudent to give the same amount by the rectum as by the mouth.

Solid substances introduced into the rectum are termed suppositories. Liquids introduced into the rectum are termed clysters, lavements, injections, and enemata. Soluble substances, when thus applied, are usually dissolved in water; insoluble substances are suspended in some mucilaginous vehicle. When the enema is to be retained, it should be from one to four fluidrachms in quantity. When it is introduced to act upon the bowels, its bulk may be from twelve to sixteen fluidounces for an adult, six to eight fluidounces for a youth of twelve, three to four fluidounces for a child of one to five years, and a fluidounce for a newly-born infant. Various instruments are used for the administration of enemata, as the pipe and bladder, the ordinary syringe, the self-injecting apparatus, and the elastic bottle and tube. Gaseous matters have also been thrown into the rectum-tobacco-smoke, for example, to relieve obstructions of the bowels.

g. To the urino-genital and vagino-uterine membranes, appli'cations are made exclusively for local purposes. Within a few years, intra-uterine medication has been a good deal employed in local affections of the uterus, but, in the injection of fluids into the uterus, there is danger of peritonitis.

3. To Serous Membranes. Irritating solutions are injected

into the cavity of the tunica vaginalis testis, in hydrocele; into the hernial sac, in hernia; and even into the pleural cavity, in pleurisy, for the purpose of producing adhesion of the sides of the sacs.

4. To Ulcers, Wounds, and Abscesses, medicines are applied chiefly for their local effects. The absorbing power of these surfaces is to be kept in mind in such applications. Cysts are sometimes cured by injections, as of iodine into cysts of the thyroid gland.

5. The injection of medicines into the Veins has been occasionally practised. The operation is, however, objectionable, from the danger of introducing air into the circulation; and it is seldom resorted to, except in the case of transfusion of blood after uterine hemorrhage.

THE CLASSIFICATION OF MEDICINES.

In treating the articles of the Materia Medica, some writers. have classified them according to their natural properties, others according to their action on the human system. To the student of medicine, a classification based upon the sensible qualities or natural affinities of medicines can be of little value, since it associates articles of the most opposite remedial properties. A classification of medicines founded on a similarity of action on the animal economy is more desirable and useful, and various arrangements of the Materia Medica have been attempted on this basis. They are all, to some extent, necessarily imperfect, owing partly to the diversified effects of medicines, and partly to our ignorance of the real nature of many of the modifications. which they produce upon the tissues. Still, the advantages of some arrangement of this kind are so numerous, that it cannot well be dispensed with.

The following classification will be found to include the more ordinary and generally received divisions of the Materia Medica, and to present the articles in convenient groups for therapeutic application.