Fig. 3. Behaviour of ts2 cells during temperature shift. Cells from the growth zone on a bacterial plate were allowed to attach to a coverslip, rinsed and placed above a temperature-controlled chamber at 22°C and observed (top two left-hand panels). The temperature was then raised to 28°C (top two right-hand panels and lower panels); the cells became rounder by 10 minutes and stopped migrating at about 20 minutes.