"A book to be set side by side with Huxley's Essays, whose spirit it carries a step further on the long road towards its goal."—_Mail and Express._ New York—G. P. Putnam's Sons—London * * * * * "_Remarkable for its simple language and clear style.... Bears the stamp of a production of an erudite scientist and a deep thinker._"—Science. The Prolongation of Life Optimistic Essays _By_ Élie Metchnikoff _Author of "The Nature of Man," etc._ _8vo. Illustrated Popular Edition. $1.75 net By mail, $1.90_ M. Élie Metchnikoff is one of those rare scientists who have found a way to lay hold of and present to the world in untechnical phraseology, intelligible to the lay mind, such results of his researches as are of universal interest and go straight home to the bosoms and business of intelligent men. _The Nature of Man_, by the same author, was one of the most fascinating books, at once popular, and scientific, which have appeared for decades. The book here in question will stand beside it as a worthy companion volume. It is satisfactory to report that, absorbed as Metchnikoff is in "material" problems, and deep as he is in the mysteries of the physical universe, these essays show him to be an optimist who speaks with no uncertain voice. A great deal of attention is given in _The Prolongation of Human Life_ to the subject of old age and its causes, with scientific observations of special cases among human beings and the lower animals. The author suggests means of prolonging life and health, while contemplating natural death with serenity, and finding that agreeable sensations accompany its approach. Beyond a certain point it seems to him a disadvantage to prolong life. Passing on from these mortuary lucubrations, the essays concern themselves with psychological matters, with optimism and pessimism and in general with questions of science and morals. The temperaments of certain great men are analyzed in studies that have for their subjects respectively Byron, Leopardi, Schopenhauer, and Goethe. In the preface the author says that he has avoided, as far as possible, repeating points which have been sufficiently treated in _The Nature of Man_. G. P. PUTNAM'S SONS NEW YORK LONDON End of Project Gutenberg's The Bacillus of Long Life, by Loudon Douglas