XVI CONTENTS 



4. Theoretical aspects of Vi-phage typing 405 



a. The adaptation of Vi-phage II 405 



b. Vi-type specificity in Salmonella typhi .... 408 



5. The practical application of Vi-phage typing. ... 412 



6. Phage- typing of Salmo?iella paratyphi B and S. 

 typhimurium 413 



7. Phage typing of other salmonellas 416 



8. Phage typing oi Staphylococcus aureus 416 



9. Phage typing of Corynebacterium diphtheriae 418 



10. Bacterial typing by identification of carried phages 419 



XXII Phage Taxonomy 421 



1. Purpose and principles of taxonomy 421 



2. Various proposals for phage classification 422 



3. Taxonomic criteria at the species level 424 



a. Serological relationship 424 



b. Size and morphology 426 



c. Chemical composition 426 



d. Latent period 426 



e. Susceptibility to inactivation 427 



f. Distinctive physiological properties 428 



g. Results of mixed infection experiments 429 



4. Possible taxonomic criteria at levels above the 

 species 431 



5. Special taxonomic criteria applicable to temper- 

 ate bacteriophages 432 



6. Relationship of bacteriophages to other viruses. . 433 



7. Importance of type specimens 435 



8. Summary 437 



Glossary 439 



Appendix: Methods of Study of Bacterial Viruses 443 



Introduction 444 



Host organisms and viruses 445 



Media 445 



Isolation of bacterial viruses 447 



Assay of host organisms 449 



Assay of phage by agar layer method 450 



Efficiency of plating 451 



Stability of viruses and selection of diluents. . . 454 



Preparation of high titer phage stocks 454 



Filtration of phage stocks 456 



