viu CONTENTS 
V. (Qualitative Cutabolic Reactions of Bacteria 71 
A. Reactions of Bacteria in Media Containing Only* Nitrogenous 
Substances (Proteins or Protein Derivatives) Which are Utilized 
for the Energy Requirements of Bacteria : 71 
B Reactions of Bacteria in Media Containing Both UtiUzable 
Nitrogenous Substances (Protein and Their Derivatives) 
and Carbohydrates 74 
Butyric Fermentation 76 
Acetic Fermentation 76 
Bacterial Synergism . ' 78 
VI. Quahtative Influence of UtiUzable Carbohydrates Upon the Elabora- 
tion of Proteolytic Enzymes 78 
VII. Quantitative Measure of Bacterial Metabolism 79 
VIII. Significance of Bacterial MetaboHsm, with Special Reference to the 
Sparing Action of Utilizable Carbohydrate for Protein ... 80 
1 . The Composition of Bacteria 80 
2. The Recognition of Bacteria 80 
IX. Fermentation and Putrefaction 83 
CHAPTER V. 
Saprophytism, P.\ra,sitism and Pathogenism. 
I. Definition and Limits 84 
II. The Cvcle of Parasitism 86 
III. The Cycle of Pathogenism 87 
IV. Distribution of Parasitic and Pathogenic Bacteria in Nature ... 89 
V. How Parasitic and Pathogenic Bacteria Reach Man 89 
A. The Occurrence of Parasitic Bacteria Upon the Bodies of Healthy 
Men and Animals 89 
B. How Pathogenic Bacteria Reach the Body 90 
1. Air-borne Infection 91 
2. Soil-borne Infection 92 
3. Water-borne Infection 93 
4. Food-borne Infection 93 
5. Animal Carriers 93 
6. Human Carriers 94 
7. Contact Infection 95 
8. Germinal and Prenatal Infection 95 
C. Portal of Entry ; Atria of Invasion 96 
1. Skin and Adnexa 97 
2. Mucous Membranes 100 
3. Genito-urinary System 104 
D. Where Bacteria Multiply in the Body 105 
E. Where and How Bacteria Escape from the Body 107 
VI. Balanced Pathogenism : Epidemiology 107 
VII. Seasonal and Annual Distribution of Pathogenic Bacteria .... 110 
Epidemiology Ill 
CHAPTER VI. 
Immunity and Infection. 
General Phenomena of Immunity 114 
I. Classification of Immunity 116 
A. Natural or Inherited Immunity 116 
1. Racial 116 
2. Indi\4dual 116 
B. Acquired or Induced Immunity 116 
1. Active Acquired Immunity 116 
2. Passive Immunity 116 
3. Mixed, Active and Passive Immunity 117 
II. Infection 118 
