A thermo-labile process, that determines the level of dark germination of New York lettuce seeds, was separated from the other miscellaneous processes during germination. It began 2hr after the start of imbibition, and completed several hr before the radicle protrusion at 15℃. The optimum temperature of the process was 15℃, and the activity of the process was zero at 28℃. Secondary dormancy may by induced by the reversible inactivation of the process at high temperature. It was suggested that the physiological role of the process is the generation of the growth potential of embryonic axes in order to overcome the restraint imposed by seed coats
