InChamaecyparis lawsonianaParl, the megaspore mother cell (MMC) differentiates in the middle and innermost region of the nucellus as is generally the case in Gymnosperms. During its development the MMC attains a size much larger than that of the surrounding somatic cells and accumulates a considerable amount of food-storage substances. These consist of starch and droplets which could be, at least partly, of lipidic nature. During prophase I the MMC becomes a fully polarized cell since all or almost all the mitochondria are restricted to the chalazal cytoplasm. In the authors' opinion this is determined by the trophically privileged position of the chalazal cytoplasm. The polarization of the chondriome determines the course of the subsequent events in such a way that the meiotic divisions give rise to a linear triad, in which the two micropylar megaspores soon degenerate while the chalazal one inherits all of the mithochondria from the megasporocyte and remains functional. On the other hand the food-storage substances appear more or less uniformly distributed at all megasporogenesis stages.