It has been found that, when suspended in phenol, the zeta potentials of Bacterium coli decrease with time. Inorganic ions had a retarding effect, particularly higher valent cations. The concentration of phenol required to sterilize a culture in 20 min was markedly increased by the presence of electrolytes, and again the higher valent cations were more efficient. Further investigation, and reference to figures 3 and 4 of part I of this paper (Davies, Haydon & Rideal 1956), showed there to be a general relationship between the sterilization concentration of phenol and the initial zeta potentials of the cells. Examination of these phenomena suggests that death and lysis of the cells are, in phenol, closely related, but there is nothing to indicate which is cause and which is effect. The conclusions do, however, provide support for the suggestions of Hotchkiss (1946) and Gale & Taylor (1947) that death of the organism in phenol is due to a lytic process.