11 CONTENTS 



XII Cytological Changes in the Infected Host Cell 189 



1. Observations on living cells 190 



2. Observations on fixed and stained preparations. . 195 



3. Electron microscope observations 202 



4. Summary 205 



XIII Isotopic Studies on the Fate of the Infecting Phage 

 Particles 207 



1. Morphological, functional, and chemical dif- 

 ferentiation of the phage particle 208 



a. Chemical composition 208 



b. Physical fractionation — osmotic shock 208 



c. Physiological fractionation- — ^the blendor ex- 

 periment 209 



d. Functional differentiation of phage protein 



and phage DNA 209 



2. The breakdown of the infecting virus particle. . . 210 



a. Absence of breakdown of phage proteins. . . 210 



b. Breakdown of phage nucleic acid following 

 superinfection 212 



3. Material transfer from infecting phage to progeny 216 



a. Lack of transfer of phage protein to progeny 216 



b. Transfer of phage nucleic acid to progeny. . 218 



c. Material transfer without genetic transfer. . 222 



d. Physical state of parental isotope during 

 transfer 226 



e. Distribution of parental isotope among prog- 

 eny particles 227 



f. Efficiency of transfer 229 



4. Summary 229 



XIV Nutritional and Metabolic Requirements for Phage 

 Production 233 



1, Requirements for adsorption and penetration. . . . 234 



2. Metabolic requirements for phage multiplication. 236 



a. Lack of metabolic enzymes in mature phage 237 



b. Enzymic activity associated with vegeta- 

 tive phage 240 



c. Enzymic activity of the host cell 242 



d. Synthetic and energetic machinery of the 

 host cell 244 



