Preface to the fourth edition.

The Ninth Revision of the United States Pharmacopoeia, as in no previous edition, makes it important, and even necessary, that all works of a pharmaceutical character be revised.

The last revision of the Pharmacopoeia has required, on the part of the revisers, very exceptional work directed toward the subject of standards; and inasmuch as the United States Pharmacopoeia, as well as the National Formulary, is mentioned in the statute, known as the Food and Drugs Law, this revision has become of greatest importance.

Recognizing this, great pains have been taken in the revision of the present edition, that the standards, whenever mentioned, shall conform to the legal standard above referred to.

Many changes have been made necessary by the fact that the U.S.P. IX has deleted fifty-three vegetable drugs and has added, or raised to official recognition, but four of well known drugs.

Among the conspicuous changes in U.S.P. IX, is the adoption of "Mil" (singular), "Mils" (plural), for cubic centimeter (cc.). This coined word, Mil—for Milliliter, is more accurate than cubic centimeter, (cc.) for the thousandth of a liter, which the cubic centimeter was intended to express. Throughout this present edition "mil" and "mils" have been used, replacing the less accurate "cc."

The Families of plants yielding organic drugs have been rearranged in the present volume. The order of arrangement adopted is that which is followed by all botanists of any note at the present time, commencing with the Algae, Fungi, and other cryptogamous growths, the order and sequence of such authors as Engler and Prantl have been practically followed. This has required an entire transposition of the natural orders of the former edition.

The Chapter on Inorganic Chemicals has been enlarged to meet the demand of many students. Added to this is a brief Chapter on Therapeutic Action, which is intended as a suggestion to students of how to expand their knowledge in this direction by reference to other works.

The chapters relating to histological study of plant tissues have been entirely omitted in the present edition in order to economize space for new material, and, secondly, because Professor Stevens, formerly associated in this work, has published an entirely satisfactory volume for class-room work and covered the ground more completely in his "Plant Anatomy."

A Chapter on Serotherapy has been incorporated which, in treatment, while it is concise, it is hoped will meet the present demand of students of Materia Medica, who first must have studied the elements of this very extensive subject.

The author desires to make special mention of valuable service rendered by his associate, Mr. Chas. M. Sterling, who has revised that portion of the work included in the various chapters of Part IV. The author regrets that he has been obliged to reduce rather than lengthen many articles in Materia Medica in order that the present volume should not be unduly expanded.

L. E. S.

A Manual of Organic Materia Medica and Pharmacognosy, 1917, was written by Lucius E. Sayre, B.S. Ph. M.