In a previous paper, it has been shown that the logarithmic order of death of bacteria can be accounted for by the assumption that each cell contains one or several extremely sensitive molecules and that the destruction or inactivation of any one of these prevents multiplication of the cell.
In this paper, the apparent exceptions to the logarithmic order are dealt with. It has been shown that the decreasing death rate can well be accounted for by the assumption of a variation in resistance of the cells under test.
The few cases of increasing death rates might be indicative of a different cell structure, requiring the destruction of 2 or 3 molecules before multiplication is made impossible. More probable, however, is the assumption that these bacteria behave exactly like the others, and that the apparently larger number of molecules per cell is caused by our imperfect method of counting living bacteria by the plating method where a cluster of several cells can be counted only as one cell. Bacteria with a tendency for clustering are likely to give results resembling the expectation for several reacting molecules per cell.
