M. Schlesinger 



The values of k (multiplied by 10^ '), calculated on the basis of our most exten- 

 sive experiments, are summarized in Table I. 



For these experiments, a phage lysate of titer 6.5 X 10* and a heat-killed bac- 

 terial suspension (70° for 1 hour) were used. Prior to heating, the bacterial 

 suspension was grown from a slant agar culture to a density of 5.8 X 10^, as de- 

 termined by colony count. However, the value of 6.5 X 10*^ used in the calcula- 

 tions was determined by microscopic cell count after heat-killing. 



Table I 



It is apparent that, neglecting variations due to experimental error, the value of 

 k remains virtually constant, in spite of the fact that in the different experiments 

 the initial titer of phage has been varied by a factor of 100, the concentration of 

 bacteria by a factor of 200 and the reaction time by a factor 360. The average 

 value of the velocity constant in these experiments is 1.2 X 10~^^ 



In five additional, less extensive, experiments, carried out with cultures of coli 

 88 grown either in broth or on agar, the following values of k were found: 1.0 X 

 10-11, 1.4 X 10-11, 1.6 X 10-11, 1.0 X 10-11, and 14 x IQ-n (average values of 

 3, 7, 9, 4, and 7 determinations). These fluctuations are no greater than the 

 uncertamty in the determination of the bacterial concentrations 2. The average 

 value of the velocity constant k, computed on the basis of 58 single determi- 

 nations for the binding to dead bacteria, was 1.3 X 10- n. 



2As has already been mentioned, the heat-killing was carried out by heating to 70° for 1 hour. 

 This temperature treatment has no important effect on the binding capacity of the bacteria. 

 In a series of experiments, ahquots from a single broth culture of coli were heat-killed at 70° 

 for i, 1, 2 and 3 hours; the adsorption velocity constants determined in e.xperiments utilizing 

 these suspensions were 1.7 X lO-n, 1.6 x IQ-i!, 1.3 X lO"" and 1.4 X 10-". 



28 



