oospore

L, M, N, Fertilization of the oogonium and development of the oospore in Peronospora.

The oospores give rise to neuter plants, the tetraspores to ♂ or ♀ plants.

The oospores of the Saprolegniæ, when arrived at maturity, possess a tolerably thick double integument, consisting of an epispore and an endospore.

After impregnation the fertilized oosphere immediately surrounds itself with a cell-wall and becomes the oospore which by a process of growth forms the embryo of the new plant.

After the production of this oospore the parent filament gradually loses its vitality and slowly decays.