Chapter I: Preface: To the English Edition

In preparing for the English-reading student this version of M. Metchnikoff’s latest work, wherein he “sums up the labours of twenty-five years,” it has been my aim to give a faithful rendering of the ideas and argument of the original, even at the risk of an occasional crude expression, rather than to attempt to reproduce the brilliancy of the original by any wide verbal departure from the text.

The Table of Contents forms an admirable analytical summary of the main subject-matters treated, but an alphabetical Index has been added to the present edition, and, though not at all exhaustive, this may serve as a key to the many authors cited and to the maze of detail discussed in the work.

The marginal reference to the pages of the original work will, I hope, commend itself to those readers who may wish to refer to the _ipsissima verba_ of the author. It is, I believe, a novelty in scientific works, though familiar in works in other departments of literature.

I am under deep obligations to Professor Woodhead (who has read the whole of the proofs) and to Mr A. E. Shipley, and Mr G. H. F. Nuttall (who have read portions) for much valuable criticism and advice.

THE TRANSLATOR.

_August, 1905._

ERRATA.

Page 93, line 2, _after_ itself _insert_ alone; line 3, _delete_ only. Page 98, line 3 from bottom, _for_ actively _read_ vigorously. Page 386, line 16, _for_ tortoise _read_ turtle. Page 461, line 21, _after_ circumstances _insert reference figure_ 1. Page 537, line 11, _for_ arise _read_ arises.

TO MESSIEURS E. DUCLAUX AND E. ROUX.

_My dear Friends_,

_Permit me to dedicate to you this work, which sums up the labours of twenty-five years; a very great part of it has been carried out by your side, you who have done so much to lighten my task._

_When, nearly fourteen years ago, you allowed me to share your work alongside the venerated Master who founded the House where we have laboured together, you were anything but partisans of my theories; they seemed to you too vitalistic, and not sufficiently physico-chemical. In course of time you became convinced that my ideas were not without foundation, and since then you have given me warm encouragement to pursue my researches in the field that I had marked out for myself._

_Working by your side and drawing largely from your vast and varied stores of knowledge, I felt myself safe from those divagations into which a zoologist, who had wandered into the domain of biological chemistry and of medical science, is likely to stray. I thank you with all my heart, and I beg you to accept the homage of this work as a testimony of my deepest gratitude and of my warmest friendship._

ÉLIE METCHNIKOFF.

_Institut Pasteur,
3 October, 1901._