Seeds of Kochia indica Wight germinate rapidly in shallow water, but their germination is retarded on moist filter-paper. The retardation is traced to a surface-active, saponin-like inhibitor, which is readily leached away in water and is adsorbed by charcoal or soil. Excised embryos may also remain dormant on filter-paper, but if rinsed in water quickly become active. Inhibition is favoured by higher temperature (30°C. as against 20° or less), especially in an atmosphere of oxygen, although once active the embryos grow rapidly in such conditions. When the oxygen concentration is reduced to 5 per cent., germination and growth are markedly retarded, but 5 per cent. CO 2 has little or no retarding effect.