Abstract
Using staphylococcal bacteriophages previously described the effect of citrate on the free phage and on its adsorption was studied. Citrate inactivated some of the phages in the free state. In broth it inhibited adsorption in all except 2 of the phages, but not in dist. water. Three phages required a specific amt.[long dash]50 ug. CaCl2 per cc. for adsorption. The others required varied amounts, for which Mg could be substituted. The citrate-sensitive phages appeared to need divalent cations for adsorption, suggesting that with at least some phages adsorption and penetration are enzymic in character. Phage K, citrate insensitive, had electrolytic requirements related geometrically to the valence of the ions used.