Occupying, as it does, a middle ground between pure experimentation and empiricism, the science of materia medica, is enriched alike from the laboratory and observations at the sick bed. It is through a combination of the results furnished through these two channels, that the typical modus operandi of any individual drug can alone be determined. There occur, however, now and then, in the therapeutics! application of certain drugs, certain deviations from this typical, and, to a degree, normal action, the correct perception and significance of which are not always understood. But a knowledge of these is of the utmost importance to the physician, as affording him an explanation of the causes of certain symptoms, and also furnishing him with a guide to his practical management of them. The records of the individual facts here indicated—the appearance of abnormal effects of drugs—are scattered throughout the most diverse parts of medical literature, and are either not at all or but superficially considered in the manuals or text-books of materia medica. For this reason I have for a long time been making a collection of these facts, examining them critically, and making additions to this collection from my own personal experience. I have presented the results of this labor in this book in the hope that they will meet a practical want, and at the same time stimulate others to further observations in the same direction.