Cytoplasmic inheritance and ultrastructure of the male generative cell of higher plants.

The ultrastructure of the generative cell of the pollen grain has been studied in two different plants: Mirabilis jalapa L., where variegation is transmitted only by the egg cell, and Pelargonium zonale AIT., where variegation can be transmitted also by the pollen grain. It was found that only in Pelargonium zonale AIT. does the male generative cell possesses a great number of proplastids.