Several factors affecting the stratification process in seeds of A. saccharum were investigated. Rates of imbibition and quantitative measurements of flow rate made with an osmometer indicate that the testa offers a severe restriction to water flow and that a significant portion of the stratification period is required for adequate water uptake. Respiration rates showed a close correlation with water uptake by the embryos throughout the stratification period. Whole seed needed 40–60 days to break dormancy; however, removal of the pericarps and tearing of the testas reduced the time needed by as much as two-thirds. Presoaking whole seed at 5 °C had a similar effect. Seeds with their pericarps removed and testas pricked and treated with gibberellic acid or kinetin provided the highest percentage germination and germinated in the shortest time. Additional tests showed that oxygen was not a limiting factor, and an inhibitor present in the pericarp evidently does not play a significant role in the dormancy mechanism. The restricted movement of water through the testa apparently controls and complements the metabolic block in the embryo and accounts for the prolonged stratification requirement.