Predicted and experimental final numbers of donors, recipients and transconjugants for initial donor numbers varied from log 1.77 to 7.77 and initial recipient numbers kept constant at log 1.86, with instantaneous conjugation (A) or conjugation occurring after 2.25 h of contact (C); initial donor numbers varied from log 1.32 to 7.32 and initial recipient numbers kept constant at log 5.2, with instantaneous conjugation (B) or conjugation occurring after 2.25 h of contact (D). Donor predictions remain unchanged and are not presented again in panels B and D. Symbols, error bars, experimental details as described in Fig. 2.