CONTENTS. 



PAGE 



Pbeface 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 



