34 BACTERIOPHAGES 



ture lysis (DeMars, 1955). Similar techniques have been used 

 to determine the amount of phage-specific complement-fixing 

 antigen present at various times in the latent period (Y. T. 

 Lanni, 1954). 



It is evident that the speed and accuracy of assay methods for 

 extracellular and intracellular mature phage and for various 

 phage components have been major factors in the very rapid 

 increase in knowledge of phage reproduction. The introduc- 

 tion of plaque counting methods into the field of animal virology 

 by Dulbecco (1952c) is permitting a parallel development in this 

 field. 



