1. A late flowering mutation arising in one of the long inbred Leaming strains, C14, shows no appreciable differences in plant or seed size at full maturity. At two weeks after planting the late plants are about half as tall as the normal inbred plants. These slower-growing plants are about six days later in silking but continue rapid growth longer and finally arrive at approximately the same height at the end of the season, This is an example of a deleterious recessive, not easily detected, that slows physiological activity.