Il y a eu une époque ou notre planète ne possédait aucun germe de vie organisée; donc la vie organisee y a commencé sans germe antérieur. Toutes les apparitions nouvelles qui ont eu lieu dans le monde se sont faites, non par l'acte incessamment renouvelé d'un Etre Créateur, mais par la force intime déposée une fois pour toutes au sein des choses.'-Ernest Renan. The utmost possibility for us is an interpretation of the process of things as it presents itself to our limited consciousness. . . . There is no mode of establishing the validity of any belief except that of showing its entire congruity with all other beliefs,'-Herbert Spencer. H. CHARLTON BASTIAN, M. A., M. D., F. R. S. Fellow of the Royal College of Physicians; Professor of Pathological Anatomy in University College, London; Physician to University College Hospital; Assistant Physician to the National Hospital for the Paralysed and Epileptic. R PREFACE. ATHER more than three years ago, in the course of some investigations upon the microscopical characters of the blood of persons suffering from acute diseases, my attention was first thoroughly given to the great question of the Origin of Life. And as so much depended upon the proper solution of this problem-not only for Science generally, but even with reference to the scientific basis of Medicine-I determined to undertake some investigations and endeavour to revise the grounds of opinion upon the subject. I did investigate, and in consequence was after a time compelled to renounce my old prepossessions, and adopt views concerning the origin of 'living' matter which are as yet only very partially accepted in the world of science. The state of professional opinion on these questions, moreover, was such that it would have been unsuitable for me to have taught new doctrines based upon facts ascertained during these investigations, without having fully and publicly stated the grounds upon which I had adopted them. At much personal sacrifice, therefore, I resolved to attempt to produce a statement of the facts which should carry conviction to the minds of others. And |