Mutants differ from Ancestor in eclipse time but not virion assembly rate at both A) 37°C or B) 42°C. Number of intracellular phages (y-axis) vs. time since the initiation of ejection into slyD cells (x-axis). Phages were pre-attached to cells at 15°C, unattached phages were removed and ejection was initiated by transferring pre-attached phages to the incubation temperature. Cells were lysed to release intracellular phages; slyD cells are not lysed naturally by ϕX174. Phage count was the same at earlier time points as at the 8 min time point. Error bars indicate ± 1 SE.