112 BACTERIOPHAGES 



different workers and for differences in antisera, these findings 

 do not necessarily explain all examples of multi-hit neutraliza- 

 tion kinetics (see Park, 1956). 



The temperature coefl^cient for the velocity constant A' was 

 determined by Burnet, Keogh, and Lush (1937) for phage CI 6. 

 The K value at 0, 37, and 45° C. was 45, 930, and 1350 min- 

 utes"'^ respectively, the Qio thus being about 2.1. Similar 

 studies were made by Kalmanson, Hershey, and Bronfenbrenner 

 (1942) with the serologically related phage T2. The A' value 

 was found to be 0.05 seconds"^ at 0° C. and 0.7 seconds"^ 

 at 37° C, corresponding to a Qjo of about 2. The Arrhenius 

 constant was determined by Hershey (1941) to be about 11,000 

 cal. per mole. The meaning of these estimates has been placed 

 in doubt by the finding of Cann and Clark (1954) that the neu- 

 tralization of activated T2 (see above) shows a Qio of only 1 .4, 

 suggesting that the process is limited solely by diffusion. How- 

 ever, their measurements, unlike earlier ones, were made using 

 media of low salt concentration. 



Essentially all serological work with viruses has been done 

 with antiserum diluted either in physiological saline or in broth 

 containing added salt because such diluents are conventional 

 in serology. Recently Jerne (1952) and Jerne and Skovsted 

 (1953) reported that physiological diluents actually inhibited 

 phage neutralization, monovalent cations above 10"^ M and 

 divalent cations above 10~^ M being inhibitory. Optimum 

 rates of inactivation were obtained in \Q~^ M NaCl containing 

 a few jug. per ml. of certain proteins which appeared to act as 

 cofactors. Highly diluted normal serum, ^gg white, and crys- 

 talline lysozyme were effective as cofactors. An anti-T4 

 serum with a K value of 600 minute"^ in broth gave under 

 optimal conditions a A value of 100,000 or more. The kinetics 

 were first order to a phage survival of 10^^ to 10~^. It has 

 long been recognized that salt concentration has a marked 

 effect on reactions involving colloidal particles because of 

 surface charges, but no one had anticipated such an astonishing 

 effect on the rate of the antigen-antibody reaction. Additional 



