CONTENTS 



PAOH 



CHAPTER I. INFECTION AND THE PROBLEM OF VIRULENCE . . 



Scope of subject. Conception of infection. Attributes of pathogenic 

 microorganisms. Forms of infection. Influences of biological adapta- 

 tion. Classification of parasites on the basis of invasive properties. 

 Factors which determine the power to invade. Fluctuations in viru- 

 lence. How microorganisms defend themselves against destruction. 

 Serum fastness, arsenic fastness, capsule formation, inagglutinability, 

 etc. Eesistance to Phagocytosis. Development of offensive properties 

 on the part of bacteria. Specificity of different infections. Chronic 

 septicaemia. ' ' Sub-infection. ' ' Selective lodgment in tissues. Locali- 

 zation and generalization. Incubation time. 



CHAPTER II. BACTERIAL POISONS 28 



Part played by bacterial poisons in clinical manifestations. Pto- 

 maines. Importance of ptomaines in disease. True toxins or exo- 

 toxins. Endotoxins. Chemotactic bacterial extracts. Basic proper- 

 ties of true toxins. Other substances biologically similar to them. 

 Analogy to enzymes. Snake venoms. Incubation time of toxins. 

 Conception of antitoxins. Work of Vaughan. Researches of Fried- 

 berger. Absorption of toxins. Selective action of toxins. Distribu- 

 tion of tetanus poison. Causes underlying selective action in general. 

 Injury done during the excretion of toxins. Union of toxins with sus- 

 ceptible cells. Importance of cell lipoids. 



CHAPTER III. OUR KNOWLEDGE CONCERNING NATURAL IMMUNITY, AC- 

 QUIRED IMMUNITY AND ARTIFICIAL IMMUNITY .... 49 



The struggle between the infectious agent and the defensive forces 

 of the body. External defenses. Skin secretions. Natural vs. arti- 

 ficially acquired immunity. Species immunity. Racial immunity. Dif- 

 ference between individuals. Inheritance of natural immunity. Im- 

 munity resulting from an attack of the disease. Jenner and smallpox. 

 Pasteur's work with chicken cholera. Active immunization. Passive 

 immunization. Pasteur's studies on anthrax. Different methods of con- 

 ferring active immunity. Methods of obtaining bacterial extracts. De- 

 velopment of our knowledge of passive immunization. Early attempts. 

 Behring and his collaborators. Ehrlich's work on ricin. Snake venom. 

 Specificity. 



CHAPTER IV. THE MECHANISM OF NATURAL IMMUNITY AND THE PHE- 

 NOMENA FOLLOWING UPON ACTIVE IMMUNIZATION ... 78 



Investigations on problems of inflammation. Metchnikoff 's earlier 

 studies. Concentration of attention upon the properties of the blood. 

 Grohman 's work. Early opposition of cellular and humoral points 

 of view. Buchner. Nuttall. Earlier arguments brought forward by 

 the two schools. Behring 's summary of the situation at this time. 

 Phenomena following upon active immunization. Earlier theories. 

 Exhaustion theory. Retention theory. Alkalinity theory. Osmotic 

 theory. Discovery of specific antibodies by Behring and collaborators. 

 Ehrlich's study on ricin. Antitoxins. Pfeiffer's discovery of lysins. 

 Agglutinins. Precipitins. Opsonins. Tropins. Conception of anti- 



