M. Schle singer 



is satisfied for very wide variations in the parameters Uo, b, and t (initial concen- 

 tration of phage, concentration of bacteria, and reaction time), provided that 

 these variations remain in such limits that the adsorption velocity is still deter- 

 mined by the same group of bacteriophages of maximal adsorptive affinity (i.e., 

 Ut/no must not fall below 1/20). 



2. The adsorption velocity constant k has the value of 1.3 X 10~^^ for adsorp- 

 tion of phage to heat-killed bacteria; k has an approximately 2.5 times greater 

 value for phage adsorption to living bacteria. 



3. A heat-killed coli bacterium is capable of adsorbing, on the average, a 

 maximum of 130 to 140 bacteriophage particles; this number is referred to as 

 the saturation capacity. 



4. On the basis of the simplest assumptions, two values for the diameter of the 

 bacteriophage have been calculated; one from the adsorption velocity constant 

 and the other from the saturation capacity; the former yields an approximate 

 particle diameter of 100 m/x, the latter a value of 60 to 120 m^u. A direct size 

 determination of the same bacteriophage from its sedimentation velocity leads 

 to a particle diameter of 80 to 90 myu- 



36 



