Transcriber’s Notes Obvious typographical errors have been silently corrected. Variations in hyphenation and accents have been standardised but all other spelling and punctuation remains unchanged. In the section on The Instinct of Life, fifth paragraph “and Flourens has reduced the ratio to that of 5:1, which would still give us 120 years.” the 120 has been corrected to 100. In Book V, Chapter III, Chemical Changes, “and at the same time would transform an amido-group into an amido-group.” is as printed. Italics are represented thus _italic_, superscripts thus y^ and subscripts thus y⌄. LIFE AND DEATH. LIFE AND DEATH BY A. DASTRE, PROFESSOR OF PHYSIOLOGY AT THE SORBONNE. TRANSLATED BY W. J. GREENSTREET, M.A., F.R.A.S. THE WALTER SCOTT PUBLISHING CO., LTD., PATERNOSTER SQUARE, LONDON, E.C. CHARLES SCRIBNER’S SONS, 153-157 FIFTH AVENUE, NEW YORK. 1911 PREFACE. The educated and inquiring public of the present day addresses to the experts who have specialized in every imaginable subject the question that was asked in olden times of Euclid by King Ptolemy Philadelphus, Protector of Letters. Recoiling in dismay from the difficulties presented by the study of mathematics and annoyed at his slow progress, he inquired of the celebrated geometer if there was not some royal road, could he not learn geometry more easily than by studying the Elements. The learned Greek replied, “There is no royal road.” These royal roads making every branch of science accessible to the cultivated mind did not exist in the days of Ptolemy and Euclid. But they do exist to-day. These roads form what we call Scientific Philosophy. Scientific philosophy opens a path through the hitherto inextricable medley of natural phenomena. It throws light on facts, it lays bare principles, it replaces contingent details by essential facts. And thus it makes science accessible and communicable. Intellectually it performs a very lofty function. There is virtually a philosophy of every science. There is therefore a philosophy of the science which deals with the phenomena of life and death—_i.e._, of physiology. I have endeavoured to give a summary of this philosophy in this volume. I have had in view two classes of readers. In the first place there are readers of general culture who are desirous of knowing something of the trend of ideas in biology. They already form quite a large section of the great public.