Vlll
PREFACE.
Under this point of view, the author is fully impressed with the valueof a physiological or therapeutical arrangement of medicines, and, couldit be effected, would readily acknowledge its vast superiority, consideredin a medical point of view, over all other classifications: but he is ofopinion that Pharmacologists are too imperfectly acquainted with theoperation of Therapeutical agents to enable them to effect a classifica-tion of this kind with much success. Scarcely two medicines give riseto precisely the same effects ; and, as we are unable to determinethe nature of the modification produced by each, “ it is impossibleto bring the substances used in medicine under a general goodarrangement b .” Every writer, who has attempted it, has found the factshitherto ascertained insufficient for his purpose, and has, therefore, beennecessarily obliged to call in the aid of theory: hence the so-calledphysiological classifications of medicines are in reality founded onthe prevailing medical doctrines of the day, or on the peculiar notionsof the writer.
Opium and mercury may be referred to in illustration of the author’smeaning. They are substances in ordinary use, and their effects are wellknown. Yet writers are neither agreed as to the nature of the primaryinfluence which these agents exercise over the animal economy, nor asto their proper position in a physiological classification.
Thus several physicians (as Dr. John Murray c and Dr. A. T. Thom-son d ) consider opium to be primarily stimulant; some (as Dr. Cullen 6and Barbier f ) regard it as sedative; one (Mayer 8 ) as both—viz., astimulant to the nerves and circulatory system, but a sedative to themuscles and digestive organs; another (Orfila h ) as neither ; while others(as MUller * *) call it alterative.
*> Elements of Physiology. By J. Muller, M.D.; translated by W. Baly, i. 57.c A System of Materia Medica and Pharmacy. 5tli ed. 1828. Edinburgh .d Elements of Materia Medica and Therapeutics. 2 vols. London . 1832.e Treatise of the Materia Medica. 2 vols. Edinburgh. 1787.
! Trade Elementaire de Mature Medicate. 2 de ed. Paris . 1824.
* Quoted by Orfila (Toxicologic Generate).
i Toxicologie Generate. 3 me ed. 1827. 2 tom. Paris .
• Op. cit.