The rate of commitment of bacterial spores to germinate after short exposure to L-alanine increases exponentially from the time of addition of L-alanine. This absence of a lag facilitates kinetic analysis and allows the dependence of commitment on temperature and pH to be determined. The pH profile of commitment has been compared with that obtained from measurements of absorbance decreases during germination, and the two profiles exhibit differing pK values. It is suggested that because the decrease in A600 of spore suspensions is a late event in germination, it is an unsuitable parameter for studying germination-triggering reactions. Commitment has been shown to be temperature-dependent, with an optimum at approx. 37 degrees C and an activation energy (mu) of 1.08 X 10(5) J/mol. The data obtained from the present studies have been used to develop a model for the triggering of germination.