EXPERIMENTS ON _THE NERVOUS SYSTEM_, WITH OPIUM AND METALLINE SUBSTANCES; MADE CHIEFLY WITH THE VIEW OF DETERMINING THE _NATURE AND EFFECTS_ OF ANIMAL ELECTRICITY. BY ALEXANDER MONRO, M. D. PROFESSOR OF MEDICINE, ANATOMY AND SURGERY IN THE UNIVERSITY OF EDINBURGH; FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS, AND OF THE ROYAL SOCIETY OF EDINBURGH, AND OF THE ROYAL ACADEMY OF SURGERY IN PARIS. EDINBURGH: PRINTED BY ADAM NEILL AND COMPANY, FOR BELL & BRADFUTE, AND T. DUNCAN; AND J. JOHNSON, LONDON. M.DCC.XCIII. CONTENTS. _Page_ INTRODUCTION, 5 Observations on the Circulating and Nervous Systems of Frogs, 6 Experiments with Opium, 9 Corollaries from the above Facts and Experiments, 12 Summary of Experiments made on Animals with Metalline Substances, 17 Summary of Facts proved by the foregoing Experiments, 35 Resemblance of the Fluid put in Motion by the foregoing Experiments to the Electrical Fluid, 38 The Nervous Fluid or Energy not the same with the Electrical, nor with the Fluid put in Motion by the foregoing Experiments, 40 General Conclusions, 42 INTRODUCTION. WHEN, in November last, I began to make Experiments on Animal Electricity, of which I read some account to the Royal Society on the 3d of December; I was not only much hurried with business, but could not procure a sufficient number of Frogs for the purpose. During the last winter and spring, I prosecuted the subject more fully and with greater attention; and, on the third day of June, I read a second paper to the Royal Society, to which I have, since that time, made additions. I shall now state a summary of the chief circumstances I have observed, with a few Remarks. OBSERVATIONS ON THE CIRCULATING AND NERVOUS SYSTEMS OF FROGS. AS my Experiments with Opium, as well as those on Animal Electricity, have been performed on Frogs chiefly; I shall premise some observations on their Circulating and Nervous Systems.