Following an accelerated ageing treatment, the radical cells of non-viable embryos of Zea mays were found to be disorganized. Organelles were swollen and did not differentiate into functional structures. During inhibition the cells deteriorated progressively and their cytoplasm lysed. Acid phosphatase activity, normally confined to lysosomal vacuoles, spread to the cytoplasm during inhibition, and this was presumed to indicate general release of hydrolytic enzymes. Loss of viability is considered to be a consequence of the deterioration of membrane systems.