EFFECT OF PHYSICAL AND CHEMICAL AGENTS 53 



cells Still retain their ability to serve as hosts for phage multi- 

 plication, another resemblance to the action of radiations. 



6. Alcohols 



Cold aqueous solutions of glycerine and ethyl alcohol do not 

 inactivate most phages, and in fact cold 30 per cent alcohol at 

 pH 5.4 has been used to precipitate phage T6 as one step in the 

 concentration and purification of this virus (Putnam, KozlofF, 

 and Neil, 1949). Undiluted glycerine and ethanol cause rapid 

 inactivation of phages (d'Herelle, 1926). Bronfenbrenner 

 (1925) studied the effect of salts on the stability of phages during 

 alcohol and acetone precipitation and concluded that suitable 

 mixtures of monovalent and divalent cations were preferable to 

 pure salts in stabilizing the phage. Wahl and Blum-Emerique 

 (1949a) used alcohol precipitation to purify phage CI 6, and 

 Hotchin (1954) used acetone to precipitate phage K. 



7. Other Chemicals 



The enzyme poisons, cyanide and fluoride, do not damage 

 phages in concentrations that are lethal to bacteria. Cyanide 

 has been used to stop phage development without inactivating 

 phage particles at desired times in the latent period (Doermann, 

 1952). Thymol and chloroform are bactericidal but do not 

 inactivate phages. Any of these substances can be used to 

 preserve phage lysates (Wahl and Blum-Emerique, 1949b; 

 Fredericq, 1952a, Sechaud and Kellenberger, 1956). 



Formaldehyde inactivates bacteriophages, but Schultz and 

 Gebhardt (1935) reported that formalin inactivated staphylococ- 

 cus phage could be reactivated by dilution. Labaw, Mosely, 

 and Wyckoff (1949) noticed a large difference between coliphage 

 Tl and phages T2 and T4 in susceptibility to inactivation by 

 formaldehyde. 



There are many observations to the effect that mercuric ion 

 inactivates phages. Krueger and Baldwin (1934) found that the 

 rate of inactivation of staphylococcus phage K by HgCl2 fol- 



