Abstract
In 1947 Pappenheimeret al. claimed concerning the mechanism of diphtheria toxin production that toxin was excreted as failure products of synthesis toward iron porphyrin enzymes. In 1951 Freeman demonstrated that nontoxigenic strains ofC. diphtheriaewere converted into toxigenic strains by lysogenization with its phage. It is not yet, however, clarified why this toxin molecule produced can be released so early into the medium or even in the logarithmic phase of the growth (Barksdaleet al., 1954) . Recently Hatano (1956) showed that the toxin was released not at the same time with the cell lysis by its phage but just a given time later than the phage issue into the medium.
In the preceding report (Nishidaet al., 1957a) the authors demonstrated that the enzyme activities ofC. diphtheriaewere easily denatured by a few conditions in the course of its shake culture. Since these findings suggested to the authors that diphtherial cells might have a more liability to degenerate in water than those of other species of microorganisms in spite of its strong resistance on solid medium or in dry circumstance (Kolleet al., 1928), an investigation was undertaken to see the stability of young cells ofC. diphtheriaesuspended in water by testing the activities of its constitutive enzymes as much as possible and by testing released protein from suspended cells. The former is described in Experiment I and the latter in Experiment II.
