X CONTENTS 



8. Phenomena Correlative with Bacteriophagy 73 



Acceleration of bacterial growth 73 



Agglutination 73 



Resume 74 



Chapter II 



THE BACTERIOPHAGE CORPUSCLE 



1. Bacteriophagy upon Solid Media 76 



2. The Bacteriophage Corpuscle 82 



3. The Plaque: A Colony of Bacteriophage Corpuscles 87 



4. Conditions Essential for Plaque Formation 88 



5. The Characters of Plaques 92 



6. Enumeration of Bacteriophage Corpuscles 96 



Resume 99 



Chapter III 



THE mechanism OF BACTERIOPHAGY 



1. The Corpuscle: Obligatory Bacteriophage 101 



2. Fixation of the Bacteriophage Corpuscle 104 



3. Penetration of the Corpuscle into the Bacterium 112 



4. Multiplication of the Bacteriophage Corpuscle 115 



The course of multiplication 116 



Influence of temperature upon multiplication 123 



Multiplication as affected by the state of the bacteria 124 



Multiplication in relation to the number of bacteria bacteriophaged. . 125 



Influence of the conditions of the medium 126 



Cause of the arrest of multiplication 127 



5. Bacteriophagy under the Microscope 130 



Resume 135 



Chapter IV 



THE VIRULENCE OF THE BACTERIOPHAGE 



1. Variation in the Activity of Bacteriophage Corpuscles 137 



2. Evaluation of the Virulence of a Bacteriophage 141 



3. Pure Races of the Bacteriophage 155 



4. Variability in the Virulence of the Bacteriophage 159 



5. Increases in Virulence 160 



6. Attenuation of Virulence 165 



7. Homogeneous and Heterogeneous Bacterial Species 168 



8. Multiple Virulences of the Bacteriophage 170 



9. Persistence of Virulence 171 



10. The Mechanism of the Persistence of Virulence 173 



11. The Acquisition of Virulence 175 



12. Bacteriophagy in Mixed Cultures 178 



Resume 179 



