Chapter II: Preface

When, ten years ago, I was preparing my _Lessons on the Comparative Pathology of Inflammation_ for the press, I hoped that the other sections of the phagocytic theory—Immunity, Atrophies, and Healing—would soon follow this first work. This hope has not been realised, and it has needed prolonged work ere I could publish the volume I have just completed.

During this long period I sent out several _ballons d’essai_ under the form of summaries of the question of Immunity, published in the _Semaine médicale_ (1892), the _Ergebnisse_ of Lubarsch and Ostertag (1886), and the _Handbuch der Hygiene_ by Weyl (1897). I there attempted, as far as possible, to give a general picture of the phenomena of Immunity in the infective diseases, and it was my desire to excite criticism and opposition, in order to determine the fate of the theory of phagocytes in its application to the problem of Immunity.

The most recent attempt in this direction was made at the International Congress at Paris, in the past year (1900), when I presented my report on Immunity before an audience which included, amongst others, my principal opponents. It was the result of this Congress which at length decided me to bring together my views on Immunity in a volume which I now present to the reader.

Convinced that many of the objections raised against the phagocytic theory of Immunity proceeded solely from an insufficient knowledge of the theory, I thought that a work condensed into one volume might render some service to those who are interested in the problem of Immunity. I do not know whether I shall convert my opponents, but I am convinced that a perusal of this book will clear away certain misunderstandings. A very competent observer recently confessed in one of his publications that for many years he had been unaware of the experiments of M. J. Bordet and myself on Immunity against the cholera vibrio, experiments which he now regards as of fundamental importance for the comprehension of the whole question of Immunity. I hope that after the appearance of this treatise such oversights will not be so likely to occur.

Should I not succeed in convincing my opponents of the justice of the cause which I defend, T shall at least have informed my critics and shall have given them an opportunity of discussing it with a thorough knowledge of the material on which it is based. This result alone would justify me in having undertaken this work.

At first I intended to add to my explanation of Immunity a theory of the phenomena of healing in infective diseases, but I soon had to renounce this project, for its execution would have increased too greatly the bulk of the book which, without it, has already assumed considerable proportions. It seemed to me preferable to set forth the present state of the question without paying too much attention to the historical sequence of the discoveries, and to reserve for a special chapter, at the end of the work, a sketch of the history of our knowledge on Immunity.

Before I ask the reader to glance through this work, I should mention that I have been heartily seconded in its preparation by many of my friends and collaborators. I offer my most sincere thanks to MM. Roux, Nocard, Massart, and J. Bordet, who kindly undertook to read my manuscript throughout, or such parts of it as related to their special subjects. For example, M. Nocard rendered me a very great service by correcting the paragraphs of Chapter xv, which treat of the vaccinations against epizootic diseases, and M. Massart, by giving me his advice on the subject of immunity in plants.

I owe very special thanks to M. Mesnil, who has been good enough to give me very effective help in the dry task of correcting the manuscript and proofs.

I beg MM. E. Rémy and L. Barnéoud to accept my thanks for the care they have bestowed on the execution of the illustrations in this work.

ÉLIE METCHNIKOFF.

PARIS, INSTITUT PASTEUR,
_3 October, 1901_.

CONTENTS.

PAGE PREFACE TO THE ENGLISH EDITION v PREFACE ix INTRODUCTION 1 Importance of the study of immunity from a general point of view.—Part played by parasites in infective diseases.—Intoxications by the products of micro-organisms.—Resistance of the organism to the invasion of micro-organisms. Natural immunity and acquired immunity. Immunity to micro-organisms and immunity to toxins.

CHAPTER I

IMMUNITY IN UNICELLULAR ORGANISMS 11
Infective diseases of the unicellular organisms.—Intracellular
digestion in the Protozoa.—Amoebo-diastase.—Part played by
digestion in the defence of the Protozoa against infective
parasites.—Defences of the _Paramaecia_ against
micro-organisms.—Part played by irritability in defence in the
lower organisms.
Immunity of unicellular organisms to toxins.—Acclimatisation of
bacteria to toxic substances.—Protective secretion of membranes
by bacteria.
Adaptation of the Protozoa to saline solutions—of yeasts to
poisons—of yeasts to milk-sugar.
Irritability of unicellular organisms and Weber-Fechner’s
psycho-physical law.

CHAPTER II

IMMUNITY IN MULTICELLULAR PLANTS 29
Infective diseases of plants.—Plasmodia of the Myxomycetes and
their chemiotaxis.—Adaptation of the plasmodia to
poisons.—Pathogenic action of _Sclerotinia_ upon
Phanerogams.—The cicatrisation of plants.—Defence in plants
against Bacteria.—Sensitiveness of vegetable cells to osmotic
pressure.—Adaptation of plants to modifications of osmotic
pressure.—Dependence of the chemical phenomena upon the
irritability of the vegetable cells.—The law of Weber-Fechner.

CHAPTER III

PRELIMINARY REMARKS ON IMMUNITY IN THE ANIMAL KINGDOM 40
Examples of natural immunity among the Invertebrates.—Immunity
against micro-organisms and insusceptibility to microbial
poisons are two distinct properties.—The refractory organism
does not eliminate micro-organisms by the excretory channels.—It
destroys them by a process of resorption.—The fate of foreign
bodies in the organism.—The resorption of cells.—Intracellular
digestion.—This digestion effected by the aid of soluble
ferments.—Digestion in Planarians and
Actinians.—Actinodiastase.—Transition from intracellular
digestion to digestion by secreted juices.—Digestion in the
higher animals.—Enterokynase and the part it plays in
digestion.—The psychical and nervous elements in
digestion.—Adaptation of the pancreatic secretion to the kind of
food.—Excretion of pepsin in the blood and in the urine.

CHAPTER IV

RESORPTION OF THE FORMED ELEMENTS 67
Digestion in the tissues.—Resorption of cells in the
Invertebrata.—Resorption of red corpuscles by the phagocytes of
the Vertebrata.—Phagocytes.—Various categories of these
cells.—Macrophages and microphages.—Part played by macrophages
in the resorption of the formed elements.—Digestive property of
the macrophagic organs.—Solution of the red blood corpuscles by
the blood serums.—The two substances which operate in
haemolysis.—Macrocytase and fixative.—Analogy of the latter with
enterokynase.—Escape of the macrocytase during
phagolysis.—Suppression of phagolysis.—Resorption of the
spermatozoa.—Presence of fixatives in plasmas.—Origin of
fixatives.

CHAPTER V

RESORPTION OF ALBUMINOID FLUIDS 106
Resorption of albuminoid substances.—The precipitins of blood
serum which appear as a result of the absorption of serums and
of milk.—Absorption of gelatine.—Leucocytic origin of the
ferment which digests gelatine.—Anti-enzymes.—Antirennet.—The
anticytotoxins.—Antihaemotoxic serums.—Their two constituent
parts: anticytase and antifixative.—Action of anticytase.—The
antispermotoxins.—Origin of anticytotoxins.—Ehrlich’s theory on
this question.—Origin of antihaemotoxin.—Origin of
antispermotoxin.—Production of this antibody by castrated
males.—The antispermofixative produced when the spermatozoa are
excluded.—Distribution of spermotoxin and antispermotoxin in the
organism.

CHAPTER VI

NATURAL IMMUNITY AGAINST PATHOGENIC MICRO-ORGANISMS 128
Natural immunity and the composition of the body
fluids.—Cultivation of the bacteria of influenza and
pleuro-pneumonia in the fluids of refractory animals.—Resistance
of _Daphniae_ to the Blastomycetes.—Examples of natural immunity
in Insects and Mollusca.—Immunity of Fishes against the anthrax
bacillus.—Immunity of frogs against anthrax, Ernst’s bacillus,
the bacillus of mouse septicaemia, and the cholera
vibrio.—Natural immunity in the cayman.—Immunity of the fowl and
pigeon against anthrax and human tuberculosis.—Immunity of the
dog and rat against the anthrax bacillus.—Immunity of Mammals
against anthrax vaccines.—Immunity of the guinea-pig against
spirilla, vibrios, and streptococci.—Natural immunity against
anaerobic bacilli.—Fate of Blastomycetes and _Trypanosomata_ in
the refractory organism.