Materia Medica and Therapeutics relate to the use of drugs in the treatment of disease. The place which these subjects occupy in the Medical Sciences lies, therefore, between Chemistry, Botany, Anatomy, and Physiology on the one hand, and Medicine and Surgery on the other hand; whilst they stand side by side with Pathology, the other stepping-stone from the more purely scientific to the more strictly practical portions of professional education. The student will now be able to turn to account his acquaintance with chemistry and biology, and to appreciate the fact that these sciences are the true foundations of all professional knowledge; and when he has reached the end of the volume he may anticipate with some confidence a personal introduction to the treatment of disease.

Let us consider what subjects are comprised under the title, "Materia Medica and Therapeutics."

Materia medica. - This term is applied to the) materials or substances used in medicine, their nam sources, physical characters, and chemical proper the preparations made from them, and the doses in which they may be given.

Therapeutics relates to the treatment of difsease, the word signifying healing, from θєpaπevw, I attend, heal, or treat. It includes, therefore, all that relates b - 8 to the science and art of healing, not merely by the application of the materia medica to the treatment of disease, but by the use of remedial measures of every kind, including diet, climate, baths, clothing, nursing, and the numerous other means which may be combined to restore health, not the least important being surgical treatment, or surgical therapeutics. This definition is manifestly far too comprehensive for our present purpose, which is concerned only with medicinal therapeutics, i.e. the uses of the materia medica. When this subject is discussed under the head of each article of the materia medica, as it comes before us in natural order, it is known by the name of the special therapeutics of that article. Materia medica and special therapeutics will constitute the first part of the work.

When the numerous and complex facts of special therapeutics are collected and examined, certain great principles may be educed from them, unfortunately still very far from being perfect, but sufficient to furnish the ground-work for a science of general therapeutics. This portion of our subject will be considered in the concluding part of the work.

Certain other terms, variously related to the preceding, must here be defined:

Pharmacodynamics (фapµakov, a drug, and δvvaµls, power) is a convenient name for that part of our subject which relates to the action of drugs upon the healthy individual, that is, the physiological action of drugs. In the first part of this work the term "action" will simply be used to express the same meaning.

Pharmacology (фapµakov, a drug, that is, either a medicine or a poison) is a term which has been employed in two senses. With the older writers in this country it is the science that relates to the chemical and physiological properties of drugs, their selection and preparation, the extraction of their active principles, and the combination of these with others. More recently pharmacology has come to be used in a wider sense, and to include the whole subject of materia medica and therapeutics, for which it is a short and convenient term.

Pharmacy is the name applied to the art which corresponds with the science of pharmacology, the art of of making the preparations indicated or ordered by the pharmacologist, and of dispensing the combinations prescribed by the therapeutist. In such a work as the present, the details of pharmacy must be mainly omitted. They have to be learned practically in the dispensary or pharmaceutical laboratory, not by rote from a book.

The Pharmacopoeia. - The number of drugs used from time immemorial is enormous, and comparatively few are now believed to be really useful, To separate the valuable materice medicoe from those supposed to be worthless, books have been published from time to time by the governments or medical authorities of different countries, which furnish an authoritative list of the drugs generally recognised and used by the profession, and the preparations made from them, which have thus become "officinal" or official. These books are known as pharmacopoeias (фapµakov, a drug, and πolєw, I make). In this country we have the British Pharmacopoeia, which provides us with a tolerably accurate list of the drugs and preparations in use at the time of its publication. But as pharmacology is a rapidly-advancing science, especially from the direction of chemistry and pharmacodynamics, and as opinion is very unsettled on the subject of therapeutics, the pharmacopoeias of different countries differ greatly; and the pharmacopeia of any given country neither is accepted at the time of its publication as perfect in itself and to be followed as an article of faith, nor remains a correct representation of professional opinion for any great length of time. It is, however, an invaluable medium of communication between the physician and the pharmaceutical chemist, whom it furnishes with formulae for a great variety of preparations of definite composition, and an immense amount of information respecting drugs which is necessary in combining these, or in devising fresh preparations.

Plan of the Materia Medica. - In the Pharmacopoeia the materiae medicae and their preparations are arranged alphabetically for convenience of reference, but in a systematic treatise they must be discussed in natural order.

The following plan will be adopted in these pages: