The organism", proposed by Hinshelwood, consists of 2 linked autocatalytic enzymes with cell division controlled by the second. The differential equations of growth in a constant medium are linear and exact results are obtained for the lag time following (a) cases where the initial conditions are changed from the stable state (mimicking transfer from an aging culture) and (b) cases where one or more of the parameters are changed (mimickingthe effect of a drug). Different causes may produce identical curves for cell number against time. Most of the curves show the classical lag form but some inverse sigmoid types occur.