Contents xiii 



CHAPTER VH 



PAGE 

 THE MECHANISM OF NATURAL IMMUNITY AGAINST MICRO-ORGANISMS . . 175 



The destruction of micro-organisms in natural immunity is an act of re- 

 sorption. Part played by inflammation in natural immunity. Importance 

 of microphages in immunity against micro-organisms. Chemiotaxis of 

 leucocytes and ingestion of micro-organisms. Phagocytes are capable 

 of ingesting living and virulent micro-organisms. The digestion of micro- 

 organisms in phagocytes is most often effected in a feebly acid medium. 

 Bactericidal property of serums. Phagocytic origin of the bactericidal 

 substance. Theory of the secretion of the bactericidal substance by 

 leucocytes. Comparison of the bactericidal power of serums and of 

 blood plasmas. The bactericidal substance of blood serums must not 

 be considered a secretion-product of leucocytes ; it remains within the 

 phagocytes, so long as they are intact. The cytases. Two kinds of 

 cytases : macrocytase and microcytase. Cytases are endo-enzymes, allied 

 to trypsins. Changes in the staining properties and in the form of micro- 

 organisms in the phagocytes. Absence or rarity of fixatives in the 

 serums of animals endowed with natural immunity. The agglutination 

 of micro-organisms does not play any important part in the mechanism 

 of natural immunity. Absence of antitoxic property of the body fluids 

 in natural immunity. The phagocytes destroy the micro-organisms 

 without their ingestion being preceded by neutralisation of the toxins. 



CHAPTER YIII 



SURVEY OF THE FACTS BEARING ON ACQUIRED IMMUNITY AGAINST MICRO- 

 ORGANISMS 207 



The discovery of attenuated viruses and its application to vaccination against 

 infective diseases. Vaccination by microbial products. Vaccination with 

 serums. The acquired immunity of the frog against pyocyanic disease. 

 The acquired immunity against vibrios. Extracellular destruction of 

 the cholera vibrio. Part played by two substances in Pfeiffer's pheno- 

 menon. Specificity of fixatives. Phagolysis and its relation to the extra- 

 cellular destruction of vibrios. Part played by phagocytosis in the 

 acquired immunity against vibrios. Fate of the spirilla of recurrent 

 fever in the organism of immunised guinea-pigs. Acquired immunity 

 against the bacteria of typhoid fever and pyocyanic disease. Acquired 

 immunity against swine erysipelas and anthrax. Acquired immunity 

 against the streptococcus. The acquired immunity of rats against 

 Trypanosoma. 



CHAPTER IX 



THE MECHANISM OF ACQUIRED IMMUNITY AGAINST MICRO-ORGANISMS . . 250 



Cytases and fixatives. Only the latter are augmented in the immunised 

 organism. Properties of the fixatives. Difference between them and 

 the agglutinative substances. The part played by the latter in acquired 

 immunity. Protective property of the fluids of the immunised organism. 

 Stimulant action of the body fluids. The protective power of serum 

 cannot serve as a measure of acquired immunity. Examples of acquired 

 immunity in which the serums exhibit no protective power. Phago- 



