EFFECT OF PHYSICAL AND CHEMICAL AGENTS 61 



factors are probably involved as well, however. Anderson, 

 Rappaport, and Muscatine (1953) describe variants of T6 

 differently sensitive to osmotic shock, and an unexpected tem- 

 perature-dependence in some of them. 



The discovery of osmotic shock was of the greatest importance 

 in contributing to an understanding of the structure (Chapter 

 IV) and function (Chapter XIV) of phage particles. 



The properties of the ghosts produced by osmotic shock of T2 

 have been studied in some detail. All observers agree that they 

 kill bacteria with a low efficiency varying between 10 and 

 50 per cent. That ghosts can adsorb to bacteria without 

 killing them is especially clear from the microscopic observation 

 of Bon if as and Kellenberger (1955) and the metabolic studies of 

 French and Siminovitch (1955), which show that the surviving 

 bacteria are damaged. Multiplication and protein synthesis 

 are interrupted for about 80 minutes, and ability to support 

 growth of superinfecting phage is temporarily lost. Since in- 

 fection with live T2 does not interrupt protein synthesis, it ap- 

 pears that ghosts and phage damage the cell in different ways. 

 For this reason it is incorrect to say that the killing power of T2 

 resides in its protein coat ; the death of the cell penetrated by a 

 ghost could be due, for example, to leakage of material through 

 fissures in the ghost. This consideration, as well as the observed 

 low efficiency of killing by ghosts, does not support the idea some- 

 times expressed that phage T2 belongs to a necessarily virulent 

 species. 



13. Summary 



Substances or conditions that denature proteins or react chemi- 

 cally with proteins or nucleic acids inactivate phages. The 

 effects tend to be phage-specific, and sometimes help in classi- 

 fication of phages. Substances that react reversibly such as 

 formaldehyde and mercuric ions cause reversible inactivation 

 under appropriate conditions. Specific enzyme poisons such as 

 cyanide, fluoride, and dinitrophenol have no effect on phage 



