Seeds of a number of weed species were buried in soil for a period of 50 weeks. At the end of this period the soil was disturbed under controlled illumination. In three species germination appeared to be unaffected by light, prior to burial. Following burial, however, germination took place only in the light, suggesting the induction of light sensitivity. In eight other species, which showed varying degrees of light sensitivity when fresh seeds were examined, germination, following burial, was completely dependent upon exposure to light. Seed germination has also been shown to be inhibited by burial under laboratory conditions. The extent of this inhibition is dependent upon the depth of burial and the water content of the medium. Experiments using artificial aeration indicate that it is the presence of a gaseous inhibitor in the soil atmosphere which prevents germination. This inhibitor appears to arise from the seeds themselves and is not carbon dioxide.