THE question of the longevity of buried seeds is always recurring, as witness the recent revival of the fable of mummy wheat. There is abundant evidence that the embryo of the wheat grain perishes relatively soon, in ten years or less under ordinary conditions. Respiration goes on until the substance of the embryo is burnt away ; extreme desiccation may prolong the process. Other seeds, however, do retain their vitality for much longer periods when dry, and when buried in earth germination may be indefinitely delayed. Possibly the tension of carbon dioxide in the soil gases slows down the respiration process ; again, we have found that humus, particularly of deep-seated peat, contains substances inhibiting germination, even when the conditions of moisture, aeration and temperature are optimum.